ALBERT

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Hayam M. Lotfy, Sarah S. Saleh, Christine M. El-Maraghy〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An analytical investigation was carried out to study the treatment and amplification of the spectral signals produced by critical concentrations with high accuracy and precision using two advanced approaches. The factorized-spectrum approach was applied through two novel methods which were: absorptivity centering technique via both: factorized zero order absorption spectrum (ACT-FSD〈sup〉0〈/sup〉〈sub〉∆A〈/sub〉) and factorized ratio spectrum (ACT-FSR〈sub〉∆P〈/sub〉). The proposed methods were found to be linear in the ranges of (15–100 μg/mL) and (3–40 μg/mL) for ASP and MTO, respectively. Those methods were compared to the methods following the geometrical standard addition approach: ratio H-point standard addition method (RHPSAM) and geometrical induced amplitude modulation (GIAM). The approaches were applied for the determination of the minor component metoclopramide in its mixture with the major component aspirin in the challengeable ratio of (1,90) respectively in a white multicomponent system. The results obtained from the proposed approaches were statistically compared with each other. The methods were validated according to ICH guidelines where the results were found to be within the acceptable limits. The methods were found to be accurate and reliable for the determination of metoclopramide critical concentration besides aspirin concentration. The results of single factor ANOVA analysis indicated that there is no significant difference among the developed methods. These methods provided simple resolution of this binary combination from synthetic mixtures and pharmaceutical preparation and can be conveniently adopted for routine quality control analysis.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519307292-ga1.jpg" width="325" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 223〈/p〉 〈p〉Author(s): Rui Zhang, Yun Liu, Lin Kong, Xian-Yun Xu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, a two photon absorbing (TPA) material consisting silver nanoparticles and triphenylamine-thiol derivative (TBS) has been prepared through interfacial coordination effect according to soft-hard-acid-base principle. The interfacial structure and morphology of the hybrid are researched in detail. Linear and nonlinear optical properties of the hybrid are studied. Upon interfacial coordination, the hybrid shows red-shifted UV–Vis absorption, causing from enhanced electronic drawing strength due to existence of Ag atom. The results also indicate that the surface Plasmon resonance (SPR) effect of Ag nanoparticles (~6 nm) brings about enhancement in single photon fluorescence emission and two photon absorption. Compared with free TBS, Ag-TBS hybrids show higher TPA cross-section (δ), which is 8784 GM for TBS and up to 103876 GM for Ag-TBS hybrid, showing ~12 fold increase. Due to excellent TPA property, the hybrids have good application in the field of optical power limiting and its limiting threshold is 0.49 J/cm〈sup〉−2〈/sup〉. This type of interfacial coordination induced hybrid provides a promising strategy to regulate linear optical properties and optimize nonlinear performance.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉A thiol-Ag nanohybrid has been prepared through interfacial coordination effect and self-assembly process to optimize the TPA performance.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519307280-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 223〈/p〉 〈p〉Author(s): Qiujuan Ma, Chunyan Wang, Yu Bai, Junhong Xu, Juan Zhang, Zhengkai Li, Xiaoyu Guo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hypochlorous acid (HClO) is an important reactive oxygen species (ROS) and plays a significant role in living organisms. Highly selective and lysosome-targetable probes for sensing hypochlorous acid are rare. In this article, we designed and prepared a new lysosome-targeting and ratiometric fluorescent probe for monitoring the levels of hypochlorous acid. 4-Aminonaphthalimide was chosen as the fluorescent group and (2-aminoethyl) thiourea group was used as a specific recognition group for HClO. A morpholine unit was employed as a lysosome-targeting group. In the absence of HClO the probe underwent intramolecular charge transfer (ICT) and showed a green emission. When excess HClO is present, the ICT process was interrupted which caused a 57 nm blue-shift of fluorescence emission from 533 nm to 476 nm. The ratiometric fluorescent probe showed outstanding selectivity toward HClO over other various bioactive species. Furthermore, the ratiometric fluorescent probe exhibited rapid response time and ability of working in a wide pH range. The linear response of I〈sub〉476nm〈/sub〉/I〈sub〉533nm〈/sub〉 toward HClO was obtained in a concentration range of HClO from 1.0 × 10〈sup〉−6〈/sup〉 to 1.0 × 10〈sup〉−4〈/sup〉 mol·L〈sup〉−1〈/sup〉. The detection limit was estimated to be 8.0 × 10〈sup〉−7〈/sup〉 mol·L〈sup〉−1〈/sup〉 for HClO. Moreover, the probe showed a perfect lysosome-targeting ability, and has been successfully used to the confocal imaging of HClO in lysosomes of HepG2 cells with little cell toxicity. All of such good properties illustrated that it could be applied to determine HClO at lysosomes in living cells.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519307243-ga1.jpg" width="158" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Markéta Paloncýová, Gustav Aniander, Emma Larsson, Stefan Knippenberg〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Visualization of membrane domains like lipid rafts in natural or artificial membranes is a crucial task for cell biology. For this purpose, fluorescence microscopy is often used. Since fluorescing probes in lipid membranes partition specifically in e.g. local liquid disordered or liquid ordered environments, the consequent changes in their orientation and location are both theoretically and experimentally of interest. Here we focused on a liquid disordered membrane phase and performed molecular dynamics (MD) simulations of the indocarbocyanine DiD probes by varying the length of the attached alkyl tails and also the length of the cyanine backbone. From the probed compounds in a DOPC lipid bilayer at ambient temperature, a varying orientation of the transition dipole moment was observed, which is crucial for fluorescence microscopy and which, through photoselection, was found to be surprisingly more effective for asymmetric probes than for the symmetric ones. Furthermore, we observed that the orientation of the probes was dependent on the tail length; with the methyls or propyls attached, DiD oriented with its tails facing the water, contrary to the ones with longer tails. With advanced hybrid QM/MM calculations we show that the different local environment for differently oriented probes affected the one-photon absorption spectra, that was blue-shifted for the short-tailed DiD with respect to the DiDs with longer tails. We show here that the presented probes can be successfully used for fluorescence microscopy and we believe that the described properties bring further insight for the experimental use of these probes.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S138614251930719X-ga1.jpg" width="417" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 223〈/p〉 〈p〉Author(s): Sheng Zhou, Ningwu Liu, Chongyang Shen, Lei Zhang, Tianbo He, Benli Yu, Jingsong Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A compact high-resolution spectroscopic sensor using a thermoelectrically (TE) cooled continuous-wave (CW) room temperature (RT) quantum cascade laser (QCL) was demonstrated for simultaneous measurements of exhaled carbon monoxide (CO) and nitrous oxide (N〈sub〉2〈/sub〉O). The sampling pressure was optimized to improve the sensitivity, the optimal pressure was determined to be 150 mbar based on an optical density analysis of simulated and measured absorption spectra. An adaptive Kalman filtering algorithm based on back-propagation (BP) neural network was developed and proposed for real-time exhaled breath analysis in order to perform fast and high precision on-line measurements. The detection limits (1σ) of 1.14 ppb and 1.12 ppb were experimentally achieved for CO and N〈sub〉2〈/sub〉O detection, respectively. Typical concentrations of exhaled CO and N〈sub〉2〈/sub〉O from smokers and non-smokers were analyzed. The experimental results indicated that the state-of-the-art CW-QCL based sensor has a great potential for non-invasive, on-line identification and quantification of biomarkers in human breath.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S138614251930722X-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 223〈/p〉 〈p〉Author(s): Susan Sadeghi, Samieh Olieaei〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The new ionic liquid capped CdS quantum dots (IL-CdS QDs) as a fluorescent probe was successfully synthesized by a hydrothermal method in a one step process and used for the facile and sensitive determination of florfenicol (FLF) in aqueous media. The new ionic liquid 3-(2-[(5-amino-1,3,4-thiadiazol-2-yl)thio]ethyl)-1-methyl-1H-imidazol-3-ium chloride (IL) was synthesized by introducing 5-amino-1,3,4-thiadiazole-2-thiol as a ligand onto the alkyl chain of the 1-chloroethyl-3-methylimidazolium chloride ILs. This task specific ionic liquid reagent was used for the capping of CdS QDs which played the role of recognition element of FLF. The IL-CdS QDs were characterized by Ultra Violet-Visible absorption -spectroscopy (UV–Vis absorption spectroscopy), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). Quenching of fluorescence intensity of the IL-CdS QDs was in proportion to the addition of FLF concentration. Under the optimum conditions, the fluorescence intensity ratio of IL-CdS QDs in the presence and absence of FLF versus FLF concentrations gave a linear response according to the Stern-Volmer equation from 0.1 to 20 μg mL〈sup〉−1〈/sup〉 (0.3 to 56 μmol L〈sup〉−1〈/sup〉) with a limit of detection 0.035 μg mL〈sup〉−1〈/sup〉 (0.098 μmol L〈sup〉−1〈/sup〉). The developed method was applied to the determination of FLF in fish and chicken meats with satisfactory results. This method revealed some advantages such as high sensitivity, precision and wide linear range to FLF. The proposed method can be utilized for rapid screening the quality of meat products.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519307395-ga1.jpg" width="382" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 223〈/p〉 〈p〉Author(s): Masoomeh Shaghaghi, Gholamreza Dehghan, Samaneh Rashtbari, Nader Sheibani, Azam Aghamohammadi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The binding of sitagliptin (SIT), an anti-diabetic drug, to human and bovine serum albumin (HSA and BSA; main serum transport proteins) was investigated using various spectroscopic and molecular docking techniques. The fluorescence data demonstrated that SIT quenched inherent fluorescence of these proteins through the formation of SIT-HSA/BSA complexes. The number of binding sites was obtained (~1) and binding constant (K〈sub〉b〈/sub〉) and effective quenching constant (K〈sub〉a〈/sub〉) were calculated as 10〈sup〉4〈/sup〉 for both systems. Based on thermodynamic parameters, the van der Waals forces and hydrogen bonding were the most important forces in the interactions between HSA/BSA and SIT, and the complex formation processes were spontaneous. The results of UV–vis absorption and FT-IR spectroscopic revealed that SIT induces small conformational changes in the structure of the proteins (HSA/BSA). The synchronous fluorescence (SF) spectroscopy demonstrated that the binding of SIT with HSA/BSA had no effect on the polarity around Trp and Tyr residues. The CD spectra showed changes in the secondary and tertiary structures of both proteins with a decrease in α-helices contents and an increase in β-turn structures. The molecular docking and spectroscopic data verified the binding mechanisms between SIT and HSA/BSA, and revealed that SIT completely fits into the hydrophobic cavity between domain II and domain III of these proteins.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519306766-ga1.jpg" width="348" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 223〈/p〉 〈p〉Author(s): Praveen Mishra, Badekai Ramachandra Bhat〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report a facile one step in-situ synthesis of amino-functionalized graphene dots. These quantum dots were employed for the detection of glucose in both standard aqueous solutions and commercially available fruit juice to assess its practicability. The characterization of the quantum dots revealed that they were decorated with amine functionality. Additionally, the interaction between glucose and amine functionalized graphene quantum dots gave enhancement in the UV–vis absorption and photoluminescence (PL) due to aggregation of quantum dots via glucose link. Therefore, the quantum dots were able to detect the concentration of glucose in solution exhibiting linearity from 0.1 to 10 mM and 50–500 mM with a sensitivity transition from 10 mM to 50 mM. The limit of detection for the determination of glucose was found to be 10 μM. This determination was agreed from both UV–Vis absorption and PL spectroscopy. However, the PL emission method of determination was most suited with its very high accuracy of 98.04 ± 1.96% and 97.33 ± 2.67% for the linear range of glucose concentration within 0.1–10 mM and 50–500 mM, respectively. The PL enhancement was highly selective towards glucose in mixture of other form of sugars making it suitable for determining glucose in food samples.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519307152-ga1.jpg" width="301" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 223〈/p〉 〈p〉Author(s): Saman Khan, Atif Zafar, Imrana Naseem〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉HSA is an important plasma protein responsible for transport of drug molecules. Coumarin derivatives play critical role as anticancer, antidiabetic and antiparkinson agents. In our lab we have synthesized coumarin-based pharmacophore, di(2-picolyl)amine-3(bromoacetyl) coumarin (ligand-L) endowed with anticancer activity. Anticancer agents binding mode of HSA provides valuable pharmacological information and is a structural guidance in synthesizing new drugs with greater efficacy. Thus, binding mechanism of ligand-L with HSA was explored using spectroscopic and molecular docking techniques. UV–Vis spectroscopy demonstrates hyperchromism in the absorbance spectra of HSA on addition of ligand-L suggesting interaction of ligand-L with HSA. Fluorescence spectroscopy indicates quenching in the fluorescence of HSA in the presence of ligand-L confirming the complex formation and this binding follows static mechanism. Steady state fluorescence spectroscopy revealed high binding affinity between ligand-L and HSA with a 1:1 stoichiometry. Thermodynamic parameters obtained by ITC suggest that the interaction between ligand-L and HSA is mainly driven by van der Waals forces and hydrogen bonds, and the negative value of ΔG is an indication of spontaneous binding process. Competitive binding and molecular docking experiments showed that the binding site of ligand-L mainly resides in sub-domain IIA of HSA. CD experiments revealed no significant conformational changes in the secondary structure of HSA on binding of ligand-L. We also found that esterase-like activity of HSA was not affected by ligand-L. In conclusion, this study demonstrates binding mechanism of ligand-L with HSA, and the binding did not induce conformational changes in HSA. This study is likely to provide better understanding of transport and delivery of ligand-L via HSA. Overall, it will provide insights into pharmacokinetic properties of ligand-L and designing new ligand-L based derivatives with greater efficacy.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519307206-ga1.jpg" width="301" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Priscilla M. de Souza, Carlos V.M. Inocêncio, Victoria I. Perez, Raimundo Crisostomo Rabelo-Neto, Vinicius Ottonio O. Gonçalves, Gary Jacobs, Frédéric Richard, Victor Teixeira da Silva, Fabio B. Noronha〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This work studied the performance of nickel phosphide phases supported on various supports (SiO〈sub〉2〈/sub〉, Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉, TiO〈sub〉2〈/sub〉, CeO〈sub〉2〈/sub〉 and CeZrO〈sub〉2〈/sub〉) for the hydrodeoxygenation of phenol in gas phase at 300 °C and 1 atm. The nature of the phosphide phase obtained by the temperature programmed reduction at 700 °C depended on the type of support. Only Ni〈sub〉2〈/sub〉P was formed on SiO〈sub〉2〈/sub〉, TiO〈sub〉2〈/sub〉, and CeZrO〈sub〉2〈/sub〉, whereas the Ni〈sub〉12〈/sub〉P〈sub〉5〈/sub〉 was the preferred phase on Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉. A mixture of both Ni〈sub〉2〈/sub〉P and Ni〈sub〉12〈/sub〉P〈sub〉5〈/sub〉 phases was obtained on CeO〈sub〉2.〈/sub〉 Unsupported Ni〈sub〉2〈/sub〉P exhibited high selectivity to benzene (95%), indicating that the Ni〈sub〉2〈/sub〉P phase is responsible for the direct deoxygenation of phenol. Ni〈sub〉12〈/sub〉P〈sub〉5〈/sub〉 phase promoted the formation of cyclohexanone, cyclohexane and cyclohexene. However, the supported catalysts showed lower selectivity to benzene, even when the Ni〈sub〉2〈/sub〉P was the only phase present. The supports favored the formation of hydrogenation products via the tautomerization route. All catalysts only slightly deactivated with time on stream, which is likely due to the high activity of the phosphide phase.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304602-ga1.jpg" width="279" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Jose L. Diaz de Tuesta, Asuncion Quintanilla, Jose A. Casas, Sergio Morales-Torres, Joaquim L. Faria, Adrián M.T. Silva, Helder T. Gomes〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉P, B and N-doped carbon blacks prepared with H〈sub〉3〈/sub〉PO〈sub〉4〈/sub〉, urea and H〈sub〉3〈/sub〉BO〈sub〉3〈/sub〉 were tested as catalysts in the wet peroxide oxidation of a concentrated 4-nitrophenol (4-NP) model solution (〈em〉C〈sub〉4-NP〈/sub〉〈/em〉 = 5 g·L〈sup〉-1〈/sup〉). The highest catalytic activity was found for P-doped carbon black (complete removal of 4-NP after 4 h at 80 °C, 〈em〉C〈sub〉cat〈/sub〉〈/em〉 = 2.5 g·L〈sup〉-1〈/sup〉, 〈em〉C〈sub〉H2O2〈/sub〉〈/em〉 = 17.8 g·L〈sup〉-1〈/sup〉 and initial pH 3, whereas 44-19% removals were reached with the other catalysts). That was ascribed to the strongest acidity (〈em〉pH〈sub〉PZC〈/sub〉〈/em〉 = 3.5) and hydrophilic character of the catalyst. Initial pH affected the oxidation, allowing to increase strongly the conversion of 4-NP with the P-doped catalyst decreasing the initial pH from 4 to 2 (4-NP removal from 20% to 99% after 8 h of reaction time at 50 °C, 〈em〉C〈sub〉cat〈/sub〉〈/em〉 = 2.5 g·L〈sup〉-1〈/sup〉 and 〈em〉C〈sub〉H2O2〈/sub〉〈/em〉 = 17.8 g·L〈sup〉-1〈/sup〉). An autocatalytic-power-law kinetic model was developed to predict the observed induction period and the dependence on the pH of the 4-NP oxidation, H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 consumption and pH evolution (〈em〉k〈sub〉4-NP〈/sub〉〈/em〉 = 2.2·10〈sup〉-5〈/sup〉 M〈sup〉-2〈/sup〉 min〈sup〉-1〈/sup〉, 〈em〉k 〈sub〉H2O2〈/sub〉〈/em〉 = 4.0·10〈sup〉-6〈/sup〉 M〈sup〉-3〈/sup〉· min〈sup〉-1〈/sup〉 and 〈em〉k〈sub〉H+〈/sub〉〈/em〉 = 5.1·10〈sup〉-3〈/sup〉M〈sup〉-0.23〈/sup〉 min〈sup〉-1〈/sup〉 at 80 °C).〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304663-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): J.J. Ternero-Hidalgo, F.F. Budihardjo, K.L. Yeung〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Rapid synthesis of zeolite thin film coating on metal surface was demonstrated for LTA, FAU, EMT, SOD, CAN and JBW on stainless steel. The direct heating of LTA-seeded stainless steel was achieved in a specially made synthesis reactor enabling rapid heat transfer that promote zeolite deposition and growth. Microns thick zeolite film can be grown on the stainless steel with an acceptable degree of intercrystalline defects in a relatively short crystallization time (i.e., 45 min). The type of zeolite deposited can be controlled from the starting composition of the synthesis mixture, the ageing time and substrate temperature enabling the preparation of both pure and mixed phase zeolites.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304894-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Hung Hai Pham, Ngoc Thuy Nguyen, Kang Seok Go, Sunyoung Park, Nam Sun Nho, Gyoo Tae Kim, Chul Wee Lee, Guillermo Felix〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, a five-lump model was proposed for kinetic modeling of asphaltene placed in a batch reactor with a commercial slurry-phase catalyst (Mo-octoate). Asphaltene was separated from vacuum residue using normal pentane. The kinetic experiments were carried out at 380∼430℃ for 1∼20 hours together with a 1,000 ppm concentration of Molybdenum in thermal and catalytic hydrocracking reaction modes. The results showed that the coke induction period and maximum maltene yield are changed with reaction temperature and time at thermal and catalytic hydrocracking. In addition, a linear relationship between coke and liquid (maltene + asphaltene remains) yields was shown so that the critical gas amount could be found as a criterion for determining the end of the coke induction period. Significantly, the kinetic model fit the experimental data well and, moreover, was found to be able to predict the moment when coke begins to form as well as maximum maltene yields.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S092058611930464X-ga1.jpg" width="245" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Mohamed M.A. Soliman, Anirban Karmakar, Elisabete C.B.A. Alegria, Ana P.C. Ribeir, Guilherme M.D.M. Rúbio, Marta S. Saraiva, M. Fátima C. Guedes da Silva, Armando J.L. Pombeiro〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Pure ZnO nanoparticles were synthesized by a sustainable precipitation method using zinc nitrate and sodium hydroxide in aqueous medium at room temperature. They were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM-EDX), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis) spectroscopy and Brunauer-Emmett-Teller (BET) analysis. The XRD patterns indicate the formation of the hexagonal wurtzite phase with high purity and SEM-EDS analysis confirm the purity and a homogenous distribution of the nanostructures. The ZnO nanostructures present plate-like agglomerates, resulting in a quasi-spherical morphology. The catalytic activity of the formed ZnO nanoparticles was evaluated towards the transesterification reaction of different carboxylic esters in the presence of various alcohols. This catalyst is highly selective for the transesterification of 〈em〉α〈/em〉-keto carboxylic ester (methyl benzoylformate) and leads to 〈em〉ca〈/em〉. 97% of product yield within 24 h of reaction time.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304869-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Lina Mahardiani, Abhijit Shrotri, Hirokazu Kobayashi, Atsushi Fukuoka〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Diels-Alder reaction is a useful method for modifying the surface of carbon materials. In this work, we functionalized activated carbon with a large number of carboxyl groups using the Diels-Alder reaction. Polyaromatic structure of activated carbon acted as a diene for addition of maleic anhydride (MA) that acted as a dienophile. Upon hydrolysis of the anhydride group in the adduct, vicinal carboxyl groups were formed. The formation of carboxyl groups by Diels-Alder reaction was proved by FTIR, solid-state 〈sup〉13〈/sup〉C NMR, CO and CO〈sub〉2〈/sub〉 evolution from TPD and Boehm titration. Titration results showed that the number of carboxyl groups increased from 0.09 mmol g〈sup〉-1〈/sup〉 to 3.06 mmol g〈sup〉-1〈/sup〉. DFT calculation showed that the concave site of the armchair edge on carbon surface was the most favorable for the Diels-Alder addition. The formation of exo-adduct was preferred with a reaction energy (Δ〈em〉E〈/em〉) of −24 kJ mol〈sup〉-1〈/sup〉. The synthesized catalyst was tested for acid-catalyzed hydrolysis of cellobiose. The catalyst showed higher activity than a catalyst prepared by oxidation in the presence of air.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304882-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Jorge Ramírez, Perla Castillo-Villalón, Aída Gutiérrez-Alejandre, Alejandro Ayala, Oscar Cruz-Garduza, Mónica Ayala, Patricia Quintana-Owen, Adolfo Romero-Galarza〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the search of insight concerning the interaction of molecules of different complexity with the desulfurization and hydrogenation sites, a series of NiMo sulfided catalysts with active particles of different morphology were tested in the hydrodesulfurization of dibenzothiophene, 4,6-dimethyldibenzothiophene, and in the hydrogenation of naphthalene and cyclohexene. The size and stacking of the NiMoS nanoparticles were modified both by increasing the Mo loading and by decreasing the metal-support interaction. The results show that not all the hydrogenation reactions take place at the same type of site, and that the hydrogenating sites at the top basal plane have greater hydrogenating power than those at the edge. The direct desulfurization of dibenzothiophene and 4,6-dimethyldibenzothiophene takes place at coordinatively unsaturated sites (CUS), whereas for the hydrogenation-desulfurization reaction route, the site where the rate controlling step takes place is influenced by the structure and reactivity of the reacting molecule. For dibenzothiophene, the rate controlling step takes place at hydrogenating sites at the top basal plane while for 4,6-dimethyldibenzothiophene it takes place at CUS. Therefore, to efficiently eliminate sulfur from molecules like 4,6-dimethyldibenzothiophene, as required in ultra-low sulfur fuels, the catalyst must have good hydrogenating capacity but more importantly, a high number of CUS.〈/p〉〈/div〉 〈h5〉Graphical Abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304651-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): E. Blanco, C. Sepulveda, K. Cruces, J.L. García-Fierro, I.T. Ghampson, N. Escalona〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the present work, the preparation and use of new supported transition metal carbides as catalyst for the conversion of guaiacol was investigated. Several metals (Mo, Re, Ru, Ni, Fe, and Cu) were impregnated over activated carbon and carburized under a mixture of H〈sub〉2〈/sub〉/C〈sub〉2〈/sub〉H〈sub〉4〈/sub〉 at 700 °C. Catalysts were characterized by XRD, N〈sub〉2〈/sub〉 physisorption, XPS, CO chemisorption, and TPR-MS. Evidence for carbide formation was obtained in the case of Mo, Re, Ni and Ru, based primarily on CO formation during the TPR-MS analysis. It was found that carbides were mainly active for primary guaiacol conversion to phenol and catechol through demethoxylation and demethylation. Completely deoxygenated products such as benzene and cyclohexane were also formed. The highest selectivity in benzene was obtained for the Re-TPR catalyst while Ni-TPR was the most hydrogenative one.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304614-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 225〈/p〉 〈p〉Author(s): Xiaotong Zhang, Yurong Shi, Lei Cai, Yong Zhou, Chuan-Kui Wang, Lili Lin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉As the third-generation organic electroluminescent materials, thermally activated delayed fluorescence (TADF) molecules have become the research focus recently. Significant solvent effect on TADF molecules were found experimentally, while theoretical investigations are quite limited. In this work, the solvent effect on photophysical properties of DCBPy and DTCBPy are investigated with first-principles calculations. The solvent polarity has slight influence on the molecular geometries and orbitals, while it can decrease the energy gap between the first singlet excited state (S1) and first triplet excited state (T1) significantly. Both the oscillator strength and the radiation rates of S1 increase with larger solvent polarity. The large energy gap between S1 and T1 induce negligible intersystem crossing (ISC) and reverse ISC rates between them, which also indicates higher triplet excited states are involved in the up-conversion process. Our results provide valuable information about solvent influence on the light-emitting properties of TADF molecules, which could help one better understand the light-emitting mechanism of them and favor the design of TADF molecules.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308637-ga1.jpg" width="301" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 225〈/p〉 〈p〉Author(s): Guanhua Ren, Siqi Zong, Zhongjie Zhu, Chao Cheng, Ligang Chen, Lu Zhou, Jianbing Zhang, Liyuan Liu, Jiaguang Han, Hongwei Zhao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉As the building blocks of proteins, amino acids serve vital metabolic functions in addition to protein synthesis and thus attract enormous interest. Here we reported the far-infrared optical properties of L-cysteine (Lcys) and its hydrochloride monohydrate (LCHM) characterized by terahertz time-domain spectroscopy. The Lcys and LCHM exhibit quite distinct characteristics in the terahertz region due to diverse collective vibrations of the molecules, which is further confirmed by the solid-state density functional theory (DFT) calculations. The presented studies indicate that the intermolecular hydrogen bonds play a critical role in the far-infrared terahertz response of Lcys and LCHM.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308662-ga1.jpg" width="449" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 225〈/p〉 〈p〉Author(s): Preeti Gupta, Faez Iqbal Khan, Sonam Roy, Saleha Anwar, Rashmi Dahiya, Mohammed F. Alajmi, Afzal Hussain, Md. Tabish Rehman, Dakun Lai, Md. Imtaiyaz Hassan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Sphingosine kinase 1 (SphK1) catalyzes the conversion of sphingosine to sphingosine-1-phosphate that acts as a bioactive signalling molecule, and regulates various cellular processes including lymphocyte trafficking, angiogenesis and response to apoptotic stimuli. Abnormal expression of SphK1 has been observed in a wide range of cancers highlighting their role in tumour growth and metastasis. This enzyme also plays a critical role in metabolic and inflammatory diseases, including pulmonary fibrosis, diabetic neuropathy and Alzheimer's disease. In the present study, we have investigated the structural and conformational changes in SphK1 at varying pH using various spectroscopic techniques. Consistent results were observed with the function of SphK1 at corresponding pH values. SphK1 maintains its secondary and tertiary structure in the pH range of 7.5–10.0. However, protein aggregation was observed in the acidic pH range (4.0–6.5). At pH 2.0, the SphK1 exists in the molten-globule state. Kinase assay also shows that SphK1 activity was optimal in the pH range of 7.5–8.5. To complement 〈em〉in vitro〈/em〉 results, we have performed 100 ns molecular dynamics simulation to examine the effect of pH on the structural stability of SphK1 at molecular level. SphK1 maintains its native conformation in the alkaline pH range with some residual fluctuations detected at acidic pH. A considerable correlation was noticed between spectroscopic, enzymatic activity and MD simulation studies. pH dependent structural changes can be further implicated to understand its association with disease condition, and cellular homeostasis with respect to protein function under variable pH conditions.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308431-ga1.jpg" width="273" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 225〈/p〉 〈p〉Author(s): Hiba Mohamed Ameen, Sándor Kunsági-Máté, Lajos Szente, Beáta Lemli〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Sulfonamides are preventive and therapeutic agents for certain infections caused by gram-positive and gram-negative microorganisms. In this work the interactions of sulfamethazine, a representative of sulfonamide antibiotics, with two β-cyclodextrin derivatives were investigated at different pH. Results show formation of stable sulfamethazine - β-cyclodextrin complexes and reflect importance of the competition of the hydrogen bonding and electrostatic interactions. The complex geometry formed is affected by the orientation of the pH-dependent dipole moment of sulfamethazine molecule and prolonged prior the sulfamethazine molecule enters into the β-cyclodextrin's cavity. Functionalization of the β-cyclodextrin molecule doesn't affect considerably the complex stabilities, therefore the native β-cyclodextrin molecule looks the simplest and most effective inclusion host to design selective and sensitive tool for sulfamethazine sensing.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308650-ga1.jpg" width="235" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 225〈/p〉 〈p〉Author(s): Adele Bosi, Alessandro Ciccola, Ilaria Serafini, Marcella Guiso, Francesca Ripanti, Paolo Postorino, Roberta Curini, Armandodoriano Bianco〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Paints used in street art are modern materials subjected to degradation processes, which are very complex and difficult to predict without taking into account of several factors. This study investigates three outdoor murals in Lazio, – namely “graffiti”, a word now used to indicate a spontaneous street art tendency consisting in images and writings realized by spray paints in public spaces to provoke passersby -with the aim to discover materials application techniques and chemical composition and figure out whether alteration phenomena occurred.〈/p〉 〈p〉Twenty-two samples were collected, and their stratigraphy was studied by optical microscopy. Fourier Transformed Infrared spectroscopy was used to identify binders and their degradation products in paints and preparatory layers, while for characterization of organic pigments used in all different stratigraphy layers of samples micro-Raman spectroscopy analyses was carried out. Furthermore, micro-Raman spectroscopy allowed to study an unusual patina formed on the surface of a pink paint.〈/p〉 〈p〉This information is useful for artists as well as for conservators, who must face numerous issues related to the preservation of this modern and labile kind of artistic expression, very fashionable nowadays but often created without care for materials duration. Conservation issues were also deepened by interviews with several contemporary mural authors.〈/p〉 〈p〉Artists underlined how contemporary murals are a very heterogeneous means of expression. Different cultural tendencies coexisting result in different attitude towards conservation.〈/p〉 〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308649-ga1.jpg" width="354" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 225〈/p〉 〈p〉Author(s): Bahareh Jamshidi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The feasibility of utilizing near-infrared (NIR) spectroscopy has been recently assessed for rapid and non-destructive detection of internal insect infestation in some fruits. Based on the findings, this technology can be used for on/in-line inspection of the fruits in terms of insect infestation if suitable instrument is selected for accurate spectral measurements and system development. The spectral range and optical measurement mode are two of the most important factors which can affect the accuracy of the spectral measurements and detection models. The aim of this study is meta-analysis of these factors' effects on the ability of NIR-based spectroscopy for non-destructive detection of hidden insect infestation in fruits. Eight studies (65 observations) were extracted based on the criteria of this study. Overall, utilizing NIR-based spectroscopy led to 13.98% error (95% CI = 10.69–17.27%) for non-destructive detection of hidden insect infestation in fruits. Spectral ranges of Vis/SWNIR (above 300 up to 1100 nm), NIR (above 780 up to 2500 nm), and Vis/NIR (above 300 up to 2500 nm) showed errors of 21.71% (95% CI = 16.56–26.86%), 13.30% (95% CI = 5.24–21.36%), and 13.65% (95% CI = 5.9–21.4%), respectively. It was noted that wavelengths above 1100 nm (NIR region) are more useful to detect insect infestation in fruit. Results also indicated that optical measurement modes of interactance, reflectance, and transmittance had errors of 6.66% (95% CI = 4.18–9.14%), 15.73% (95% CI = 10.99–20.47%), and 16.04% (95% CI = 7.26–24.82%), respectively. This meta-analysis suggests that utilizing interactance mode for spectra measurement in NIR-based spectroscopy can increase the accuracy of discrimination of insect infested fruits especially when the spectral range of the spectrometer is Vis/SWNIR. Moreover, it should be selected a spectrometer with the wavelength range of NIR or Vis/NIR when using reflectance or transmittance mode is necessary for developing an in/on-line system to detect insect infestation in fruits.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 337〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: Available online 3 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Iskra Z. Koleva, Hristiyan A. Aleksandrov, Georgi N. Vayssilov〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Using periodic density functional calculations we clarified the variations of the electronic structure of platinum clusters and nanowires upon their deposition on reducible and on non-reducible oxide as well as upon adsorption of carbon monoxide. Three models of platinum clusters and nanowires deposited on ceria surface and one on gamma-alumina surface were studied. At high CO coverage, when the metal cluster or nanowire is completely covered by CO, there is clear depletion of the occupied Pt 5d-projected states close to the Fermi level and appearance of a new state at lower energies, in the region around −1.5 eV below the Fermi level. Thus, in total the 5d states are stabilised and the d-band center in all systems shifts to lower energies, which is an indication that the reactivity of the platinum clusters decreases upon adsorption of carbon monoxide. According to the calculated d-band center value, the metal cluster on gamma-alumina is the most reactive (in terms of electron-donating properties) as its d-band center is located at higher energy compared to platinum on ceria. For most of the models the most stable adsorption position of CO is linear to a platinum atom from the upper part of the platinum moiety, while for the largest model the most stable position is bridging between two platinum atoms.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304092-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 16 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): D. Grigoriou, D. Zagoraios, A. Katsaounis, C.G. Vayenas〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The reaction of CO〈sub〉2〈/sub〉 hydrogenation is of high environmental interest since it allows for the transformation of the logistically challenging H〈sub〉2〈/sub〉, gained from renewable sources, to the much more manageable hydrocarbons. Ruthenium is a catalyst widely used to produce methane from CO〈sub〉2〈/sub〉. In this study we present an example of how Electrochemical Promotion of Catalysis (EPOC) can elucidate the role of solid electrolytes (YSZ, BZY) supporting Ru porous films or nanoparticles. It is found that the sign of the charge (-/+) of the current-conducting species of the electrolyte has a profound effect on the selectivity of Ru during CO〈sub〉2〈/sub〉 hydrogenation. Using this insight, we have developed and tested a new supported Ru-Co catalyst for the production of higher hydrocarbons.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119300318-ga1.jpg" width="237" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 12 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Chanon Auepattana-aumrung, Kongkiat Suriye, Bunjerd Jongsomjit, Joongjai Panpranot, Piyasan Praserthdam〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Na〈sup〉+〈/sup〉 and H〈sup〉+〈/sup〉 of ZSM-5 having three Si/Al molar ratios (20, 35, and 50) were synthesized to investigate and illustrate 1-butene cracking mechanism. The physical and chemical properties of ZSM-5 were described by XRD, SEM-EDX, N〈sub〉2〈/sub〉 physicsorption, FT-IR, pyridine-IR, 〈sup〉1〈/sup〉H MAS NMR, TPO, and NH〈sub〉3〈/sub〉-TPD techniques. For the characterization, the Na-ZSM-5 consisted of two main types of acid sites (weak and medium acid sites), whereas strong, medium, and weak acid sites were detected on H-ZSM-5. For H-ZSM-5, the Si-(OH)-Al site (strong Brønsted site) was an active site for 1-butene cracking reaction, while the active site of Na-ZSM-5 in the reaction was silanol nest (moderate Brønsted site). The 1-butene cracking reaction on H-ZSM-5 and Na-ZSM-5 was studied under the operating condition of temperature =500 °C, pressure =1 atm, and WHSV =3 h〈sup〉−1〈/sup〉. The oligomerization, cracking, and hydrogen transfer were three main reactions in the 1-butene cracking mechanism. The alkenes excluding propylene occurred on weak acid site, while the formation of propylene underwent on medium acid site of ZSM-5 catalyst. The presence of strong acid site on ZSM-5 catalyst promoted the hydrogen transfer reaction, which provoked the alkane formation. The hydrogen transfer index in 1-butene reaction of Na-ZSM-5 was less than H-ZSM-5 in all Si/Al molar ratios because of the absence of strong acid. The Na-ZSM-5 (Si/Al molar ratio = 20) reached the highest propylene selectivity at 31.73 C-wt.% and the Na〈sup〉+〈/sup〉 ion could block the strong acid site. At low Si/Al molar ratio, the stability of Na-ZSM-5 was higher than H-ZSM-5 because of the lower coke formation. Therefore, the Na-ZSM-5 was more suitable catalyst than H-ZSM-5 for propylene formation in 1-butene cracking reaction.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S092058611930433X-ga1.jpg" width="350" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 12 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Arturo Claudio-Piedras, Rosa Ma. Ramírez-Zamora, Brenda C. Alcántar-Vázquez, Albina Gutiérrez-Martínez, Gilberto Modragón-Galicia, Fernando Morales-Anzures, Raúl Pérez-Hernández〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Pt nanocatalysts supported on CeO〈sub〉2〈/sub〉-NR (CeO〈sub〉2〈/sub〉-nanorods) were synthesized and evaluated in the steam reforming of methanol reaction (SRM) for hydrogen production. The effect of Pt precursor was investigated using tetraaminplatinum nitrate (Pt(NH〈sub〉3〈/sub〉)〈sub〉4〈/sub〉(NO〈sub〉3〈/sub〉)〈sub〉2〈/sub〉), platinum acetylacetonate (CH〈sub〉3〈/sub〉-COCHCO-CH〈sub〉3〈/sub〉)〈sub〉2〈/sub〉Pt and hexachloroplatinic acid (H〈sub〉2〈/sub〉PtCl〈sub〉6〈/sub〉*6H〈sub〉2〈/sub〉O). The catalysts were characterized by N〈sub〉2〈/sub〉 Adsorption-Desorption (BET), MEB, DRX, TPR, HAADF-STEM, Mass Spectroscopy (MS) and DRIFT. All samples showed typical diffraction peaks of the fluorite CeO〈sub〉2〈/sub〉 phase cubic structure. TPR profiles of Pt/CeO〈sub〉2〈/sub〉-NR(Nit) and Pt/CeO〈sub〉2〈/sub〉-NR(Acac) catalysts, showed reduction peaks at temperatures lower compared with those of Pt/CeO〈sub〉2〈/sub〉-NR(Cl) catalysts. STEM-HAADF characterization revealed the presence of small Pt nanoparticles on Pt/CeO〈sub〉2〈/sub〉-NR(Nit) but not for Pt/CeO〈sub〉2〈/sub〉-NR(Acac); this finding was associated with the catalysts synthesis solvent used. Pt/CeO〈sub〉2〈/sub〉-NR(Nit) sample showed the best performance on methanol conversion than other catalysts, this result was associated with a larger number Pt nanoparticles distributed along the CeO〈sub〉2〈/sub〉-NR. Low catalytic activity observed on the Pt/CeO〈sub〉2〈/sub〉-NR(Cl) sample, was associated with formation of oxychlorinated Pt〈sub〉x〈/sub〉O〈sub〉y〈/sub〉Cl〈sub〉z〈/sub〉 species. Although MS technique showed stable methanol conversion during the reaction, no further changes in the outlet signals on the real-time monitoring analysis by MS was observed, this indicates that the catalyst was very stable during the reaction.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304341-ga1.jpg" width="378" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 3 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): E.V. Parkhomchuk, K.V. Fedotov, V.S. Semeykina, A.I. Lysikov〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Polystyrene microsphere-template method was used to prepare a range of hierarchically porous alumina samples. Different ways for creating hierarchical porosity were implemented, including mixing of alumina precursor with dry powder of PS microspheres and with PS water suspension, followed by extruding the resulting composite and its calcination. The samples were studied by BET technique, Hg porosimetry and scanning microscopy, mechanical strength of alumina pellets was also measured. In comparison with the “dry” method, the “wet” one gives pellets with a narrower distribution of macropores in size and the greater material mechanical strength. In whole the approach allows tuning textural parameters of hierarchically porous alumina samples in the following range: BET specific surface area 90–300 m〈sup〉2〈/sup〉/g, mesopore volume 0.30–0.65 cm〈sup〉3〈/sup〉/g, total pore volume 0.50–1.20 cm〈sup〉3〈/sup〉/g, mechanical crushing strength of 10–35 MPa. Ordered macroporosity of alumina was obtained by the impregnation of dry PS colloidal crystal by ethanol-water solution of aluminum oxalate; this method can be used only to produce small quantities or films of the material.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119303876-ga1.jpg" width="269" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 3 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Fei Yan, Yushuai Sang, Yunfei Bai, Kai Wu, Kai Cui, Zhe Wen, Fuhang Mai, Zewei Ma, Linhao Yu, Hong Chen, Yongdan Li〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Re〈sub〉2〈/sub〉O〈sub〉7〈/sub〉 is used to convert guaiacol in alcohols at 280–320 °C. In ethanol, guaiacol is deoxygenated and alkylated, and the major products are phenol and alkylphenols (including ethylphenol, diethylphenol, diisopropylphenol, di-tert-butylphenol and 2,6-di-tert-butyl-4-ethylphenol), accounting for 97 mol% of all products after 6 hour reaction at 320 °C. Both catechol and phenol are the intermediates of guaiacol demethoxylation. Among the substituents, ethyl is directly provided by ethanol while isopropyl and tert-butyl are formed by the addition of methyl to ethyl step by step. In addition, Re〈sub〉2〈/sub〉O〈sub〉7〈/sub〉 has negligible activity for the saturation of benzene ring so it does not cause considerable over-consumption of reductant. The actual catalyst for guaiacol demethoxylation is likely a Re〈sup〉IV−VI〈/sup〉 species.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119303785-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 12 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Alechine E. Ameh, Chuks P. Eze, Edith Antunes, Mero-Lee U. Cornelius, Nicholas M. Musyoka, Leslie F. Petrik〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Coal fly ash (class F) was used as feedstock to extract silica for the indirect synthesis of BEA zeolite via a hydrothermal process. The extraction steps selectively retained major components of Si 〉 Al 〉 Na and eliminated the need for the addition of an extra silica source in the zeolite synthesis mixtures. The stability of BEA zeolite was studied in hot liquid phase at different exposure times (6, 12 and 24 h) and temperatures (150 and 200 °C). The structural changes in the framework of the treated zeolite was determined with X-ray diffraction, thermogravimetric analysis, N〈sub〉2〈/sub〉 adsorption–desorption and 〈sup〉27〈/sup〉Al and 〈sup〉29〈/sup〉Si magic-angle spinning nuclear magnetic resonance. Structural degradation of the treated zeolite depended on prolonged exposure time and high temperature, reduced crystallinity and framework Si/Al ratio, the degree of desilication, and the presence of silanol defects. The relative crystallinity and changes in framework Si/Al ratio were shown to depend on the exposure time and temperature in hot liquid phase. With prolonged exposure time, the surface area and micropore volume decreased with an increase in the mesopore volume. The stability of BEA zeolite was influenced by the hydrolysis of Si-O-Si bonds (siloxane) through desilication which eventually caused the formation of structural defects at elevated treatment time and temperature, however, the crystal structure remained intact. Herein, the stability of fly ash based BEA zeolite in hot liquid shows its potential use as a catalyst for liquid phase reactions, considering the exposure time and temperature investigated.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304274-ga1.jpg" width="373" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 5 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Yanning Qu, Renliang Huang, Wei Qi, Mingbo Shi, Rongxin Su, Zhimin He〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Zinc oxide (ZnO) nanomaterials are functional photocatalysts that show excellent photocatalytic activity, among which diverse morphologies, such as nanospheres, nanorods, nanoleaves, nanodisks, or nanoflowers, often possess different photocatalytic activities. In this study, we employed a simple ultrasonic treatment to controllably synthesize three types of three-dimensional (3D) fluffy ZnO nanoflowers with different nanostructures. Specifically, one nanoflower with smooth edges was formed via direct hydrothermal reaction without ultrasonic treatment (denoted as ZnO-0), and the other two with different jagged margins were obtained by ultrasonic treatment at 250 W and 950 W, respectively, before the hydrothermal procedure (denoted as ZnO-250 and ZnO-950). The results showed that the size, specific surface area, crystallite dimension, intrinsic donor defects and the signals of reactive radicals of ZnO nanoflowers all decreased with increasing ultrasonic intensity. Furthermore, the photocatalytic performance of such ZnO nanoflowers with similar morphologies but different nanostructures was investigated using methyl orange (MO) as a model pollutant. As expected, ZnO-0 possessed the highest photocatalytic activity with a kinetic constant of 0.0478 min〈sup〉−1〈/sup〉, while the value decreased to 0.0251 min〈sup〉−1〈/sup〉 and 0.013 min〈sup〉−1〈/sup〉 for ZnO-250 and ZnO-950 under simulated sunlight irradiation, respectively, suggesting that the photocatalytic efficiency of ZnO nanoflowers decreased due to the ultrasonic treatment. These findings provide structural insight into the photocatalytic activity of ZnO nanoflowers.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304171-ga1.jpg" width="324" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 30 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): M. Tsvetkov, J. Zaharieva, M. Milanova〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ferrites of the type MFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉, where M = Zn, Co, and Mg, were prepared 〈em〉via〈/em〉 a sol-gel procedure using propylene oxide as a gelating agent. Silver nanoparticles with an average size of 6 nm were prepared in the presence of the ferrite powders in suspension using raffinose as a reducing agent in a basic water solution. Nine samples of the ferrite/silver nanoparticles nanocomposites were prepared in this way with different Ag content. The composites obtained were characterized by XRD, TEM, and UV/Vis spectroscopy. The size distribution of the particles was determined using the data from TEM. By TEM-EDAX, the location of the silver nanoparticles on the ferrite surfaces was determined. Using UV/Vis spectra, the band gap energies for the pure ferrites and the nanocomposites were calculated; the calculated band gap energies were influenced by the presence of the silver nanoparticles. The photocatalytic activity of the silver nanoparticles/ferrite nanocomposites for decomposition of Malachite Green in model water solutions under UV and visible light irradiation was determined. The ZnFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉/Ag-NPs nanocomposites were found to be active under visible light irradiation, while the MgFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉/silver nanoparticles composites especially active more than the pure MgFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉. The presence of silver nanoparticles did not influence the very low photocatalytic activity of CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉Mechanism of the Malachite Green degradation under light irradiation in the presence of Ag-NPs modified ferrites MFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 (M = Mg, Zn).〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304080-ga1.jpg" width="310" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: Available online 12 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Anup Kumar Sasmal, Arun Kumar Sinha, Kaushik Mallick, Tarasankar Pal〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Chromism from phosphomolybdate – malachite green dye moiety through hydrogen bonding interaction with water molecules is reported. Interestingly, the substance with bound di-nitrogen or di-oxygen together with water molecules also exhibits color change. N〈sub〉2〈/sub〉 or O〈sub〉2〈/sub〉 binding vis-à-vis chromism is a new insight.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304377-ga1.jpg" width="249" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 13 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Guangyuan Zhao, Miaomiao Li, Liyin Wang, Dongzhe Wang, Jinsheng Liang, Gang Xue〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The tourmaline/manganese-iron-cerium-oxide composites prepared by the hydrothermal method was investigated for NOx removal in simulated flue gas. The microstructure of the catalyst has been characterized by X-ray diffractometer (XRD), temperature-programmed reductions (TPR) and X-ray photoelectron spectra (XPS). The incorporation of tourmaline could remarkably enhance the activity of tourmaline/Mn-Fe-Ce catalyst at low temperature. H〈sub〉2〈/sub〉-TPR results indicated that H〈sub〉2〈/sub〉 adsorption amount decreased after the incorporation of tourmaline. The XPS results revealed that the incorporation of tourmaline could enhanced the contents of high valence 〈em〉O〈/em〉〈sub〉α〈/sub〉 (〈em〉O〈/em〉〈sub〉α〈/sub〉/〈em〉O〈/em〉) in the composite catalysts, which is favorable for oxidation process of elemental manganese. Overall, the catalytic performance of tourmaline/Mn-Fe-Ce was closely related to the addition of tourmaline. When the addition of tourmaline was 2%, the composite catalyst showed the best catalytic performance: The NOx conversion of the composite catalyst is 100% at 170–230 °C. Moreover, the denitrification mechanism of composites was studied. The addition of tourmaline improved the catalytic process, and stable bidentate nitrate species was activated at low temperature during the denitrification reaction. As a mineral material, tourmaline has excellent far-infrared properties and spontaneous polarization properties, which can significantly improve the denitration performance of the catalyst. The use of mineral materials as raw materials to prepare denitration catalysts provides new ideas for future research.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304390-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 2 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Seunghyun Jo, JunHwa Kwon, Ki-Yeop Cho, Dong Hyeon Kim, KwangSup Eom〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, the effect of a predeposited Co-Ni layer on the catalytic activity and long-term durability of the quaternary Co-Ni-P-B catalyst for the hydrogen evolution reaction (HER) is investigated. To study the effect of predeposition of the Co-Ni layer for the Co-Ni-P-B catalyst, both Co-Ni-P-B/Co-Ni/Cu and Co-Ni-P-B/Cu catalysts are prepared. The current density for HER of the Co-Ni-P-B/Co-Ni/Cu catalyst at −0.5 V〈sub〉RHE〈/sub〉 is 36.1% higher than that of Co-Ni-P-B/Cu in 0.5 M H〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉 solution at 18 °C. This is because the porous morphology of the Co-Ni-P-B/Co-Ni/Cu catalyst leads to a 10.6% larger electrochemical surface area and higher atomic ratio for both the P and B contents, which act as a proton acceptor and a supplier of electrons to the d orbital of the transition metals, respectively, compared to Co-Ni-P-B/Cu on the catalytic surface. Furthermore, the Co-Ni-P-B/Co-Ni/Cu catalyst retains 94.5% of the catalytic activity during durability test of 1 h owing to its higher adhesion strength between the substrate and catalyst and rougher morphology, whereas the Co-Ni-P-B/Cu catalyst shows a retention of only 64.4%.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119303566-ga1.jpg" width="431" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 2 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Dong Wook Kwon, Somin Lee, Jongsik Kim, Kwan-Young Lee, Heon Phil Ha〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The roles of WO〈sub〉3〈/sub〉 and SiO〈sub〉2〈/sub〉 in Ce-V catalysts supported on TiO〈sub〉2〈/sub〉 comprised tungsten-silica were investigated systematically for NH〈sub〉3〈/sub〉-SCR (selective catalytic reduction) and NH〈sub〉3〈/sub〉-oxidation at high temperatures. When SiO〈sub〉2〈/sub〉 and WO〈sub〉3〈/sub〉 were added to TiO〈sub〉2〈/sub〉, the surface area of Ce-V/TWS was maximized and the formation of Ti〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉O〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Si bond reduced nanoparticle size compared to without SiO〈sub〉2〈/sub〉. The Ce-V/TWS surface had greater abundance of catalytic defects and surface oxygen species 〈em〉via〈/em〉 XPS results. Increasing the (V〈sup〉4+〈/sup〉 + V〈sup〉3+〈/sup〉) fraction increased the catalytic activity, which is attributed to the enhanced SCR performance at a wide temperature range due to the addition of WO〈sub〉3〈/sub〉 and SiO〈sub〉2〈/sub〉 to TiO〈sub〉2〈/sub〉. The catalysts using the TWS supports exhibit high catalytic activity, since WO〈sub〉3〈/sub〉 and SiO〈sub〉2〈/sub〉 can promote redox properties. It was shown that Ce-V/TWS was the most suitable catalyst for selectively producing N〈sub〉2〈/sub〉 〈em〉via〈/em〉 thermodynamically unavoidable NH〈sub〉3〈/sub〉 direct oxidation as the temperature increased. In addition, hydrothermal aging effects were investigated for the Ce-V/TWS catalyst prepared by TiO〈sub〉2〈/sub〉 supports including WO〈sub〉3〈/sub〉 and SiO〈sub〉2〈/sub〉 (comparison with vanadium-tungsten/titania). This study demonstrates the feasibility of utilizing WO〈sub〉3〈/sub〉 and SiO〈sub〉2〈/sub〉 in the TiO〈sub〉2〈/sub〉 support as a possible way to increase catalytic activity and N〈sub〉2〈/sub〉 selectivity in NH〈sub〉3〈/sub〉-SCR at high temperatures.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119303554-ga1.jpg" width="268" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 12 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): J.E. Samaniego-Benitez, L. Lartundo-Rojas, A. García-García, H.A. Calderón, A. Mantilla〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉ZnS/MoS〈sub〉2〈/sub〉 composite material was prepared by one-step solvothermal method at different molybdenum concentration. The structural properties of the composite material were analyzed by XRD, UV–vis DRS, TEM and XPS techniques, and the photocatalytic was evaluated for the hydrogen production under UV irradiation. The hydrogen yield reaches 606 μmol h〈sup〉−1〈/sup〉 g〈sup〉−1〈/sup〉 for the material with 10% of molybdenum, which was 30 and 50% superior than that obtained using MoS〈sub〉2〈/sub〉 and ZnS as photocatalyst, respectively. The increase in the photocatalytic activity may be associated to a synergistic effect produced by the interaction between ZnS and MoS〈sub〉2〈/sub〉, as well as the formation of defects in the structure of ZnS, due to sulfur vacancies produced during the synthesis, which could be observed in the TEM analysis of the composite material.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304328-ga1.jpg" width="374" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 12 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): G. Bonura, C. Cannilla, L. Frusteri, E. Catizzone, S. Todaro, M. Migliori, G. Giordano, F. Frusteri〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A significant boost to the catalytic technology of CO〈sub〉2〈/sub〉-to-DME hydrogenation in a single step was recently given by the design of novel hybrid multimetallic/zeolite systems. However, a significant drop of catalyst activity after few hours of operation time pushes now the research interest towards the development of more stable multifunctional systems, suitable to ensure activity, selectivity and lifetime under typical industrial conditions. In this work, the influence of different home-made zeolite samples (〈em〉i.e.〈/em〉, Sil-1, MFI, Y, FER, BEA, MOR), integrated in a weight ratio of 1:1 with a CuO-ZnO-ZrO〈sub〉2〈/sub〉 metal-oxide(s) phase, was investigated under long-term stability tests in a fixed bed reactor during CO〈sub〉2〈/sub〉 hydrogenation reaction to assess the activity-selectivity pattern of the hybrid catalyst as well as their deactivation trend during operation time. The individuation of key structure-activity relationships helped to explain how the extent of interaction between the metal-oxides phase with the zeolite surface as well as the strength of the acid sites significantly control the catalyst stability.〈/p〉〈/div〉 〈h5〉Graphical Abstract〈/h5〉 〈div〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304353-ga1.jpg" width="182" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈p〉Deactivation rate and interface metal-to-zeolite contact area (〈em〉θ〈/em〉〈sub〉M/Z〈/sub〉).〈/p〉 〈/div〉

Description: 〈p〉Publication date: Available online 13 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Mingxiu Liu, Ondřej Veselý, Pavla Eliášová, Mariya Shamzhy, Pengbo Lyu, Lukáš Grajciar〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Tetrahydropyranylation (THP) has been extensively studied experimentally with both Brønsted and Lewis acid-based catalysts, such as zeolites, considered. However, our atomic-level understanding of the underlying mechanisms of different types of catalytic sites remains limited, particularly regarding zeolites. Thus, we combined an experimental catalytic study with density functional theory (DFT) calculations to identify the active sites and corresponding reaction mechanism in MFI zeolite. Both experimental and computational data clearly show that Brønsted acid sites are more reactive than Lewis acid sites. Furthermore, calculated reaction barriers for Brønsted acid site catalysis (5 kcal mol〈sup〉-1〈/sup〉) are much lower than those for the diffusion of bulky products in microporous channels (approximately 20 kcal mol〈sup〉-1〈/sup〉). In full agreement with theoretical calculations, the results of Madon-Boudart test clearly show that the effect of diffusion on the H-MFI catalysts performance cannot be neglected even at low temperature. Therefore, the diffusion becomes the rate-determining step. Overall, our findings suggest that designing zeolites with improved THP catalysis performance requires focusing on acid zeolites with Brønsted acid sites of average strength with facilitated diffusion, e.g., due to auxiliary mesoporous system.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304389-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 30 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Anchittha Liu, Supareak Praserthdam, Suphot Phatanasri〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The carbon dioxide reforming of methane is one of the processes used to tackle global warming by reducing carbon dioxide, one of the most harmful greenhouse gases through the catalytic reaction with methane which produces syngas. Although the noble metals are good candidates for such a process, the cost and scarcity limit their uses. The non-noble metals on the other hand, with satisfactory activity and cost, are of interest except their stability against the coke formation, the main deactivation scheme during the dry reforming reaction. Therefore, the study of the enhanced stability found in the bi-metallic system of Ni catalysts via the introduction of Co was carried out in this work. The activity and coke resistance were studied on both mono and bi-metallic system of the Ni-based catalysts (10%wt) supported on γ-Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-HY zeolite prepared via the sol-gel method. The activity testing was performed in a fixed-bed reactor with a unity feed volume ratio under atmospheric pressure at 973 K, where the Ni–Co bi-metallic system exhibits higher activity than both mono-metallic of either pure Ni or Co due to a higher number of active sites confirmed by the CO chemisorption. On the stability testing, the high stability was found on the bi-metallic system as verified by the time-on-stream testing. In addition, the higher reduction temperature for the bi-metallic system via the analysis using H〈sub〉2〈/sub〉-TPR also suggested stronger metal-support interaction which may decrease the bonding strength of the coke on the surface leading to lower deactivation.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304031-ga1.jpg" width="350" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 12 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Ren Wei Chang, Chin Jung Lin, Sofia Ya Hsuan Liou, Miguel A. Bañares, M. Olga Guerrero-Pérez, Rosa María Martín Aranda〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The modification of ordered mesoporous carbon (OMC) via NH〈sub〉3〈/sub〉 heat treatment and subsequent amine refluxing at increased temperature was investigated to improve their performances for cyclic CO〈sub〉2〈/sub〉/N〈sub〉2〈/sub〉 separation stability and kinetics. Characterizations conducted with nitrogen adsorption/desorption isotherm, Fourier transform infrared spectroscopy, elemental analysis, and X-ray photoelectron spectroscopy demonstrated that the porosity and surface chemistry of the OMCs were tuned by modification. Adsorption evaluation with volumetric and gravimetric methods under various conditions indicated that the resulting amine-introduced N-doped OMC presented a high CO〈sub〉2〈/sub〉 adsorption capacity with fast kinetics, outstanding selectivity at 50 °C and maintained superior separation performance after 20 cycles. The presence of accessible amino groups in considerable amounts renders the modified mesoporous carbon a promising candidate for CO〈sub〉2〈/sub〉 capture from flue gas by using the temperature swing adsorption.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304250-ga1.jpg" width="230" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 12 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Silvia Carlotto, Girolamo Casella, Luca Floreano, Alberto Verdini, Ana P.C. Ribeiro, Luísa M.D.R.S. Martins, Maurizio Casarin〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Fe(II) spin state in the condensed phase of [Fe(II)Cl2(tpm)] (tpm = [tris(pyrazol-1-yl)methane]; 1) catalyst has been determined through a combined experimental and theoretical investigation of X-Ray Absorption Spectroscopy (XAS) at the 〈sup〉Fe〈/sup〉L〈sub〉2,3〈/sub〉-edges and 〈sup〉N〈/sup〉K-edge. Results indicated that in this phase a mixed singlet/triplet state is plausible. These results have been compared with the already know Fe singlet spin state of the same complex in water solution. A detailed analysis of the electronic structure and bonding mechanism of the catalyst showed that the preference for the low-spin diamagnetic ground state, strongly depends upon the ligands, the bulk solvent and the interaction of the complex’s vacant site (the sixth) with a further ligand. Moreover, comparison of the electronic properties of the complex in condensed phase and water solution showed an increased Lewis acidity of the catalyst in solution phase, due to a decreasing of the LUMO energy of about 8 kcal/mol. These results gave an overall picture of the electronic behavior of the complex investigated, on going from condensed to water solution phase, explaining the preferred use of 1 as catalyst in homogeneous catalysis. The N〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Fe(II) interaction has been thoroughly investigated by means of DFT Kohn-Sham and EDA bond analysis applied to i) the isolated [Fe(II)Cl〈sub〉2〈/sub〉(tpm)] and ii) the [Fe(II)Cl〈sub〉2〈/sub〉(tpm)] interacting with water as a solvent within the Conductor-like Screening Mode (COSMO) framework. Results showed that both tpm→Fe(II) σ and tpm⟵Fe(II) π Charge Transfer (CT) interactions characterize the Fe(II)–tpm interaction. Moreover, the three tpm N atoms do not equally interact with the Fe(II) and one of them shares a suitable available iron-based d virtual orbital, to bind a further ligand in trans position.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304316-ga1.jpg" width="268" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 30 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Humayun Shariff, Muthanna H. Al-Dahhan〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A steady-state diffusion model comprising of diffusion and reaction in a catalyst pellet was used to study and understand the effect of the approximation of the catalyst effectiveness factor in the modeling of trickle bed reactors. The hydrogenation of alpha-methylstyrene was chosen as the case study reaction from literature for liquid-limited reaction conditions. The effectiveness factor values in this study were sensitive to reactor scale equations during the prediction of reactor performance. The approximation of accounting the overall catalyst effectiveness factor in the reactor scale model equations from different models and solving the reactor scale model equations by different modeling approaches was assessed. These modeling simulations were compared against the experimental results. It was observed that evaluating the overall effectiveness factor from pellet scale model equations and integrating the parameter in the reactor scale axial dispersion model at every local axial collocation point to simulate the reactor performance showed better agreement to the experimental data. This approach evaluates the effectiveness factor locally at different axial points across the reactor rather than using one value for the entire reactor. The approach of using a single effectiveness factor for the whole bed and using the effectiveness factor approximated as a fitted polynomial to the reactant concentrations did not properly predict the reactor performance.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119303931-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 2 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): L. Satish K. Achary, Pratap S. Nayak, Bapun Barik, Aniket Kumar, Priyabrat Dash〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A facile chemical synthetic route has been demonstrated for the synthesis of copper oxide nanoparticles decorated phosphate functionalized graphene oxide (〈em〉CuO/PGO〈/em〉). The synthesized nanocatalyst was used as an efficient and active candidate for the synthesis of β-amino carbonyl compounds via a green synthetic ultrasonic route. The structural properties of the samples were investigated by means of a number of sophisticated techniques like X-ray diffraction (XRD), Fourier-transform Infrared (FTIR) spectroscopy, High Resolution Transmission Electron Microscope (HRTEM), N〈sub〉2〈/sub〉 adsorption-desorption measurements, X-ray photoelectron spectroscopy (XPS) analysis, Ammonia temperature programmed desorption analysis (NH〈sub〉3〈/sub〉-TPD) and Raman spectroscopy. HRTEM analysis confirmed the presence of spherical CuO nanoparticles distributed uniformly throughout the PGO surface. XPS analysis demonstrated the presence of Cu〈sup〉2+〈/sup〉 species and minor reduction of oxygen functional groups on GO. A higher surface area of 162 m〈sup〉2〈/sup〉/g for 〈em〉CuO/PGO〈/em〉 was found from N〈sub〉2〈/sub〉 adsorption-desorption isotherms. Later on, the presence of acidic groups on 〈em〉CuO/PGO〈/em〉 that play an essential role in the catalytic activity was examined by NH〈sub〉3〈/sub〉-TPD and pyridine adsorbed IR analysis. The total acidity on the surface of synthesized nanocatalyst was found to be of 0.59 mmol g〈sup〉−1〈/sup〉 which includes both Lewis as well as Brönsted acidic sites. A higher product yield of 95% in a shorter period of time of 15 min was achieved which is superior to many reported catalytic systems. A combined strategy involving greener and easier ultrasonic route and use of an efficient acidic graphene oxide-based catalyst resulted in higher catalytic activity and stability with with good recyclability.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Highly efficient and active CuO nanoparticle decorated Phosphate functionalised graphene oxide (PGO-CuO) nanocomposite has been synthesized in a water-isopropanol system and used as an active catalyst for the synthesis of β-amino carbonyl compounds via Mannich reaction by using a greener ultrasonic method.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304067-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 30 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Sanchari Basu, Narayan C. Pradhan〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Vapor phase hydrogenation of acetone was carried out over Cu-Al mixed oxide catalysts. The catalysts were synthesized via co-precipitation method with Cu:Al atomic ratio varied from 0.25 to 1. The characterization of the catalysts was done by using XRD, BET, FESEM (coupled with EDS), FTIR, H〈sub〉2〈/sub〉-TPR, NH〈sub〉3〈/sub〉-TPD and CO〈sub〉2〈/sub〉-TPD. The performance of the synthesized catalysts was evaluated in a continuous packed bed reactor by varying parameters such as temperature (150 to 225 °C), H〈sub〉2〈/sub〉/acetone mole ratio (0.5 to 1.25) and space-velocity (0.09 to 0.145 kmol acetone/kg cat. h). Along with direct hydrogenation, condensation of acetone also occurred due to the presence of basic and acidic sites in the catalysts. The catalyst having Cu:Al atomic ratio of 0.5 showed highest selectivity (98%) to isopropyl alcohol at 175 °C. Kinetic study was conducted at different temperatures by varying space-velocity. LHHW type model rate equations were fitted with the kinetic data obtained at three different temperatures. The activation energy of the reaction was determined to be 44.3 kJ/mol.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304079-ga1.jpg" width="258" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 16 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Toru Murayama, Satoshi Ishikawa, Norihito Hiyoshi, Yoshinori Goto, Zhenxin Zhang, Takashi Toyao, Ken-ichi Shimizu, Shutoku Lee, Wataru Ueda〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉High dimensionally structured W-V-O catalysts (HDS-WVO) were synthesized by hydrothermal method and catalyst structures were investigated by HAADF-STEM analysis. HDS-WVO were rod-shaped crystals and the cross-sections were constituted by W〈sub〉6〈/sub〉O〈sub〉21〈/sub〉 pentagonal units and MO〈sub〉6〈/sub〉 octahedra (M = V, W), forming heptagonal and hexagonal channels. HDS-WVO catalysts showed excellent catalytic performance for selective oxidation of toluene to benzoic acid, and the activity and the selectivity to benzoic acid were superior to those of state-of-the-art catalysts. After the ion exchange using Cs〈sup〉+〈/sup〉, the catalytic activity over HDS-WVO was significantly decreased. Since HAADF-STEM analysis and N〈sub〉2〈/sub〉 adsorption revealed that Cs〈sup〉+〈/sup〉 was located mainly at the heptagonal channel of HDS-WVO, it can be concluded that toluene oxidation takes place at the heptagonal channel site of HDS-WVO.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119300793-ga1.jpg" width="211" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 12 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Lorena P. Rivoira, Verónica A. Valles, María L. Martínez, Yanika Sa-ngasaeng, Siriporn Jongpatiwut, Andrea R. Beltramone〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The catalytic oxidation of different sulfur compounds, commonly present in liquid fuel, was studied over a series of ceria and ceria-zirconium based oxidation mesoporous catalysts. SBA-15 was synthesized using sol-gel method and Ce and Ce-Zr were added by two different procedures: i) directly during the synthesis and ii) via post-synthesis method. The catalysts were characterized by XRD, N〈sub〉2〈/sub〉 adsorption isotherms, XPS, DRUV-Vis, TEM, SEM and Py-FTIR. Low angle XRD, N〈sub〉2〈/sub〉 isotherms and TEM confirmed that the structure was not changed after metal incorporation. Wide angle XRD, UV–vis-DRS, XPS and TEM determined that the catalysts prepared by direct synthesis presented higher dispersion of Ce oxides, smaller particle size and isolated Zr〈sup〉4+〈/sup〉 species. FTIR of adsorbed/desorbed pyridine indicated that zirconium as promoter increases the Lewis acidity of the catalysts, especially during direct synthesis. Ce-Zr-SBA-15 catalyst prepared by direct synthesis was very active in the oxidation of dibenzothiophene, 4,6-dimethyl dibenzothiophene and benzothiophene using hydrogen peroxide (H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉) as oxidant agent and acetonitrile as polar solvent. The effect of acidity in the catalyst, hydrogen peroxide concentration and temperature was studied. The deactivation test demonstrated that the catalyst is stable and adequate for the industrial process.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304262-ga1.jpg" width="425" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 225〈/p〉 〈p〉Author(s): M. Bala Divya, Lalitha Guruprasad〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An ionic liquid (IL) is a salt in which the ions are poorly coordinated, resulting in these solvents being liquid below 100 °C or even at room temperature. ILs generally consist of large sized anions and cations, have certain unique advantageous properties and hence are considered as ‘green solvents’. Thermal stability of the α/β-serine hydrolase (SH) domain in PE1 and PE2 proteins of 〈em〉Mycobacterium tuberculosis〈/em〉 (〈em〉M.tb〈/em〉) possessing esterase activity was studied in the presence of aprotic ILs consisting of imidazolium cations and anions. Addition of ILs to an aqueous solution of proteins prevented their unfolding and aggregation at higher temperatures. The thermal denaturation curve of proteins with ILs shifted to higher temperatures compared to the absence of ILs from CD spectra. The remaining activities of PE1/PE2 proteins with 1.4 M [EMIM][BF〈sub〉4〈/sub〉], [EMIM][Cl], [BMIM][BF〈sub〉4〈/sub〉] and [BMIM][Cl] exhibited 100%/100%, 58.96%/58.84%, 78.92%/78.94% and 54.63%/54.92% greater activities, respectively after the heat treatment at 30 °C for 35 min. We conclude that the remaining activities of both proteins are sufficiently maintained after the heat treatment and this depends upon the nature, concentration of ILs, and the thermal incubation time. Specifically, [EMIM][BF〈sub〉4〈/sub〉] and [BMIM][BF〈sub〉4〈/sub〉] exhibit higher thermal stabilization compared to [EMIM][Cl] and [BMIM][Cl].〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308674-ga1.jpg" width="424" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 19 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy〈/p〉 〈p〉Author(s): Jie Zhang, Suoping Peng, Yucong Wei, Shaohui Zheng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Non-fullerene acceptor based organic bulk heterojunction solar cells have been a hot topic because their power conversion efficiencies have been up to 16.35%. Functionalized 6,13‑bis (trimethylsilyl alkynyl) pentacenes with strong electron withdrawing groups, which can be easily modified to improve charge transport properties and film morphology, seem to be promising soluble non-fullerene pentacene-based organic acceptors. But how the substitutions of electron withdrawing groups influence their electronic structures, then change the absorption spectra and power conversion efficiencies, is still not clear. In this paper, we utilize density functional theory and time-dependent density functional theory to study the effects of substitutions of different electron withdrawing groups (〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉CN, 〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉CF〈sub〉3〈/sub〉, 〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉NO〈sub〉2〈/sub〉) and different positions of these groups in 6,13‑bis (trimethylsilyl alkyl) pentacene molecule on their physical and optical properties. We find that the experimental power conversion efficiencies are positively/negatively correlated with calculated dipole moments/exciton binding energies of these functionalized molecules. The computed results indicate that the molecules substituted with CN group have much larger dipole moment than the others. For the same electron withdrawing group, the dipole moment at the R2 position is generally larger than that at the R1 position. Furthermore, we find that the calculated exciton binding energy of these molecules functionalized at the R2 position is lower than that at the R1 position. In addition, the result of absorption spectra confirm that these functionalized 6,13‑bis (trimethylsilyl alkynyl) pentacenes have stronger absorption strength than C60 in the both visible and the ultraviolet regions.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308704-ga1.jpg" width="301" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 225〈/p〉 〈p〉Author(s): Chenguang Yang, Hao Deng, Yuanyuan Qian, Mingxing Li, Bing Chen, Zhenyu Xu, Ruifeng Kan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report measured line intensities and air- and self-broadening coefficients for fifty-one carbon disulfide transitions in the ν1 + ν3 band near 4.6 μm. This spectral region was chosen due to the strong carbon disulfide absorption strength and in the range of the mid-infrared atmospheric window for laser-based sensing applications. Spectroscopic parameters were determined by spectra measuring with quantum cascade laser direct absorption spectroscopy and multi-line fitting with Voigt lineshape. These measured results would facilitate the development of calibrated-free mid-infrared carbon disulfide sensors.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308686-ga1.jpg" width="484" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 225〈/p〉 〈p〉Author(s): Tatyana Emelina, Anna Zadoroznaya, Irina Kalinovskaya, Anatolii Mirochnik〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The luminescent and photochemical properties of europium(III) cinnamates [Eu(Cin)〈sub〉3〈/sub〉]〈sub〉n〈/sub〉 (I) and Eu(Cin)〈sub〉3〈/sub〉·(phen) (II) were investigated in theoretical and experimental aspects. The high photostability of the complex I was explained. The complex II displays weak luminescence and low photostability in spite of the presence of a powerful antenna ligand 1,10-phenantroline in its coordination sphere. The unexpected luminescent and photochemical properties of europium(III) cinnamates were interpreted by the quantum chemistry methods. It was revealed that inclusion of phen molecule into Eu(Cin)〈sub〉3〈/sub〉 complex results in lengthening of Eu-Cin distances that promotes weakening of antenna effect. In the process of photoexcitation of this complex noticeable lengthening of Eu-Cin-2 bond takes place and Cin-3 ligand is detached from the molecule that is the cause of low photostability and weak luminescence of II.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308716-ga1.jpg" width="363" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 31 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Fuping Li, Min Ao, Gia Hung Pham, Yun Jin, Minh Hoang Nguyen, Nabil Majd Alawi, Moses O. Tade, Shaomin Liu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Dimethyl ether (DME) has received great attention as a promising clean fuel and industrially important intermediate. Tremendous efforts have been made to develop highly active and stable catalysts for DME production. Here, we present the first example of the application of metal-organic framework (MOF) catalyst in DME synthesis from syngas. A Zr-MOF (UiO-66) was selected as the catalyst host and support owing to its exceptionally high stability and porosity. UiO-66 was firstly functionalized by silicotungstic acid (H〈sub〉4〈/sub〉SiW〈sub〉12〈/sub〉O〈sub〉40〈/sub〉, STA) via a one-pot synthesis method and then loaded with Cu by a facile solid grinding method. The prepared catalysts were characterized using XRD, TGA, FT-IR, N〈sub〉2〈/sub〉 adsorption and TEM. The high porosity and thermal stability of acidified UiO-66 were maintained after 15% wt STA incorporation without any destruction of the Keggin structure of STA. The catalyst was tested for one step DME synthesis from syngas, showing higher DME selectivity and space-time yield than control catalysts. The superior activity of Cu/STA-UiO was attributed to the uniform dispersion of active centres with close intimacy and high density of Brønsted acid sites, as well as strong metal support interaction between Cu and Zr oxide SBU evidenced by XPS analysis.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304183-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 16 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): O.A.L. Galán, G. Carbajal-Franco〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉It is known that a given material can exhibit different catalytic performances by deploying different crystallographic orientations on the surface, which can increase the reactivity of the system. This work is based on the experimental results of a previous work, where a ZnO thin film presented a (103) preferred orientation, raising the interest to investigate its catalytic performance on NO and CO by using DFT calculations. Three different conditions of the surface are considered in this work: a defect-free surface, pre-adsorption of O〈sub〉2〈/sub〉 and pre-adsorption of OH molecules. Calculations demonstrated that CO and NO catalytic reactions are improved primordially by the pre-adsorbed species on the material. ZnO (103) defect-free surface presents higher affinity to NO on the three tested sites. In the case of pre-adsorbed oxygen, the surface presented higher reaction energies for CO. In both conditions, the gases were oxidized to NO〈sub〉2〈/sub〉 and CO〈sub〉2〈/sub〉 respectively. In the case of pre-adsorbed OH radicals, the final products were nitrous acid (HNO〈sub〉2〈/sub〉) and carboxyl groups (COOH), bonded to the surface with different energies depending on the adsorption site. ZnO (103) surface proved to be reliable for using it in reactions involving pre-adsorbed oxygen and OH molecules.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304249-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 3 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Heon Lee, Byung-Joo Kim, Young-Kwon Park, Jung-Sik Kim, Sang-Chul Jung〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To improve the photocatalytic performance of TiO〈sub〉2〈/sub〉 photocatalysts, a new method, liquid phase plasma (LPP) method, was used to introduce nitrogen and iron oxide. Interstitial or substitutional nitrogen and Fe〈sup〉3+〈/sup〉 iron nanoparticles were impregnated on the surface of TiO〈sub〉2〈/sub〉 by LPP reaction without additional chemical reduction agent and the amount of iron of modified TiO〈sub〉2〈/sub〉 photocatalysts was affected by the amount of initial precursor. The adsorption edge of modified TiO〈sub〉2〈/sub〉 photocatalysts was shifted to the visible region in proportion to the amount of nitrogen and iron oxide, and the band gap energy was decreased, and the photocatalytic activity was confirmed by PL and EPR analysis. The photocatalytic activities of modified TiO〈sub〉2〈/sub〉 photocatalysts were measured under UV and blue LED lamps and compared with pure TiO〈sub〉2〈/sub〉 powder (P-25). The modified TiO〈sub〉2〈/sub〉 exhibited better photocatalytic degradation performance than pure TiO〈sub〉2〈/sub〉 under blue LED light conditions, but exhibited low degradation activity under UV LED light conditions. Through GC–MS analysis, it was found that the methylene blue was finally decomposed into an inorganic substance through intermediates such as benzene sulfonic acid and phenol by OH radicals. From these results, we found that the modified TiO〈sub〉2〈/sub〉 photocatalysts can be easily prepared using the LPP method and can be used in the visible region.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119303621-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 3 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Sasithorn Kuhaudomlap, Piyasan Praserthdam, Masayuki Shirai, Joongjai Panpranot〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nickel-doped spherical silica (SSP) catalysts with ca. 10 wt% Ni were prepared via a sol-gel method using cetyltrimethyl ammonium bromide as the structure directing agent with different loading sequences of Ni and Si sources (Si1_Ni2, Ni1_Si2, and Ni_Alt_Si). For comparison purposes, the SSP supported Ni catalysts were also prepared by impregnation method (Ni/SSP (Imp)). All the prepared catalysts showed spherical shape with high specific surface area (357-868 m〈sup〉2〈/sup〉/g). The X-ray diffraction and H〈sub〉2〈/sub〉-temperature programmed reduction results revealed the stronger interaction between Ni and SiO〈sub〉2〈/sub〉 in the form of nickel silicate for all the Ni-doped SSP catalysts except Ni/SSP (imp), in which only NiO species were detected. For the reaction temperature 350 ̊C, the CO〈sub〉2〈/sub〉 conversion was in the order: Ni〈sub〉_〈/sub〉Alt〈sub〉_〈/sub〉Si (51%) 〉 Ni1〈sub〉_〈/sub〉Si2 (49%) 〉 Si1〈sub〉_〈/sub〉Ni2 (28%) 〉 Ni/SSP (Imp) (10%) with methane selectivity 80–95%. The superior performances of the Ni_Alt_Si catalyst were correlated well to the higher electron density of Ni on the surface and higher CO〈sub〉2〈/sub〉 adsorption ability as revealed by the X-ray photoelectron spectroscopy and CO〈sub〉2〈/sub〉-temperature program desorption results.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119303979-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 3 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Rocío Magdalena Sánchez-Albores, Bianca Yadira Pérez-Sariñana, C.A. Meza-Avendaño, P.J. Sebastian, Odín Reyes-Vallejo, J. Billerman Robles-Ocampo〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The present study synthesized powders of bismuth vanadate-alumina (BiVO〈sub〉4〈/sub〉-Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉) by means of the microwave-assisted hydrothermal method. The powders prepared were characterized by X-ray diffraction, scanning electron microscopy (SEM) and UV–vis diffuse reflectance spectroscopy. The photocatalytic activity of the synthesized powders was determined via the oxidative degradation of methylene blue (MB) in aqueous solution under the irradiation of visible light. The effect of parameters such as alumina concentration, synthesis temperature and reaction time was examined in order to determine their influence on crystal size, morphology, photocatalytic activity and the type of crystal structure. The sample prepared under conditions of 160 °C, 60 min and 1.5 wt % Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉, presented the highest percentage of degradation and photonic efficient of all samples, which was close to 86% and 4.86 × 10〈sup〉−6〈/sup〉 respectively, under the parameters of the experimental design proposed for this research.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉The particles synthesized from BiVO〈sub〉4〈/sub〉-Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 with a mixture of monocyclic-tetragonal structure, showed better removal of the blue methylene dye, than the pristine form BiVO〈sub〉4〈/sub〉.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304006-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: Available online 12 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): M. Pérez-González, S.A. Tomás〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Photocatalytic Ag-loaded (TiO〈sub〉2〈/sub〉)〈sub〉0.95〈/sub〉-(ZnO)〈sub〉0.05〈/sub〉 thin films were synthesized by the sol-gel dip-coating method, with the Ag content varying in the range 1–4 mol%. The films were deposited on glass substrates at room temperature and then annealed at 500 °C. Raman spectroscopy disclosed basically the anatase phase of TiO〈sub〉2〈/sub〉. Secondary ion mass spectrometry measurements proved the incorporation of Ag in the films, revealing its diffusion to the film surface as a consequence of thermal treatments. X-ray photoelectron spectroscopy (XPS) was used to study in detail the chemical composition and electronic structure of the samples. The O 1s, Ti 2p, and Zn 2p core level spectra indicated Ti〈sup〉4+〈/sup〉 and Zn〈sup〉2+〈/sup〉 states associated with TiO〈sub〉2〈/sub〉 and ZnO regions. The chemical species identification was confirmed by calculating the modified Auger parameter for O, Ti, and Zn. In addition, an XPS depth profile analysis using an Ar〈sup〉+〈/sup〉 ion gun showed the formation of Ti〈sup〉+2〈/sup〉 and Ti〈sup〉+3〈/sup〉 oxidation states as a consequence of the Ar〈sup〉+〈/sup〉 bombardment. The photocatalytic activity under UV irradiation was evaluated by the degradation of methylene blue aqueous solutions, with the best response corresponding to (TiO〈sub〉2〈/sub〉)〈sub〉0.95〈/sub〉-(ZnO)〈sub〉0.05〈/sub〉 thin films doped with 2 mol% Ag.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304304-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 5 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): José Valecillos, Eva Epelde, Jonathan Albo, Andrés T. Aguayo, Javier Bilbao, Pedro Castaño〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The benefits of H-ZSM-5 zeolite modification with H〈sub〉3〈/sub〉PO〈sub〉4〈/sub〉 or ZnCl〈sub〉2〈/sub〉 have been analyzed during the methanol to olefins (MTO) reaction. The catalysts were prepared, characterized and tested using three different reactors: fixed-bed, operando FTIR and UV–vis. The spent catalysts were further characterized for analyzing the nature and location of the species trapped. The results show that the zeolite modified with H〈sub〉3〈/sub〉PO〈sub〉4〈/sub〉 has suffered a simultaneous dealumination, leading to a decrease of number of acid sites and activity. However, the zeolite modified with ZnCl〈sub〉2〈/sub〉 shows the inclusion of Zn transforming Brønsted into Lewis acid sites, leading to reaction intermediates (hydrocarbon pool species) that decreases the rate of reaction but improves propylene selectivity (+10%), slows downs coke formation (-42%) and expands catalytic lifetime (+80%). The distinct effect of Zn modification, typically associated with the promotion of aromatics, is explained on the grounds of the severe transformation of the strong and Brønsted acid sites.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304201-ga1.jpg" width="371" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 17 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Li Chen Kao, Wen Chen Kan, Rosa Maria Martin-Aranda, Maria Olga Guerrero-Perez, Miguel Á. Bañares, Sofia Ya Hsuan Liou〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The silica supported niobium oxide catalysts with abundant acid active sites were successfully fabricated and demonstrated catalytic activity in the acetalization of glycerol with acetone to produce solketal. Although Niobium pentachloride which was used as the niobium precursor preferred to aggregate on the surface, the chemical vapor deposition method was introduced to remove the surface chloride. The synthesis parameter of the material affects the structure and the type of the supported niobium oxide on the carrier, and directly changes the amounts of catalytic sites. The effect of calcination temperature/time and loading amount of hydrated niobium oxide on the catalytic performance was investigated. The properties of acid sites on catalysts were characterized, and the catalytic process was directly observed by operando Raman. These in-situ experimental trials could provide deep insight to understand the catalytic mechanism.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304286-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 12 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Yury I. Bauman, Ilya V. Mishakov, Yuliya V. Rudneva, Anton A. Popov, David Rieder, Denis V. Korneev, Alexandra N. Serkova, Yury V. Shubin, Aleksey A. Vedyagin〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A series of micro-disperse Ni〈sub〉1-x〈/sub〉Pt〈sub〉x〈/sub〉 alloys with the sponge-like structure was prepared by a simultaneous precipitation method with subsequent sintering of the sediment in H〈sub〉2〈/sub〉 atmosphere at 800 °C. The formation of single-phase solid solution Ni〈sub〉1-x〈/sub〉Pt〈sub〉x〈/sub〉 was confirmed by powder XRD analysis for entire range of Pt concentrations (1.3–75.9 wt.%). The synthesized samples were studied in a process of catalytic decomposition of C〈sub〉2〈/sub〉H〈sub〉4〈/sub〉Cl〈sub〉2〈/sub〉 at 600 °C. In situ kinetic studies of the carbon deposition process were carried out in a flow gravimetric setup equipped with McBain balances. Interaction of Ni-Pt alloys with reaction mixture is characterized by an induction period (18–32 min) followed by rapid disintegration of the bulk alloys with intensive growth of carbon fibers. The stage of the induction period was explored in detail by means of XRD and SEM techniques. According to XRD data, the interaction of Ni-Pt alloys with C〈sub〉2〈/sub〉H〈sub〉4〈/sub〉Cl〈sub〉2〈/sub〉 vapors is accompanied by formation of Ni〈sub〉1-x〈/sub〉Pt〈sub〉x〈/sub〉C〈sub〉δ〈/sub〉 interstitial solution due to entry of carbon into the crystal lattice of the alloy. The effect of Pt addition on catalytic activity of Ni in CCVD process was also studied. It was found that the yield of carbon product depends extremely on Pt concentration with a maximum at C〈sub〉Pt〈/sub〉 =4.3 wt.% (26 g/g〈sub〉Ni〈/sub〉 for 120 min). The impact of Pt concentration upon morphology and structural features of the produced carbon fibers was investigated by SEM and TEM techniques.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304365-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 12 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Yuan-Yuan Geng, Chun-Lan Tao, Shi-Fang Duan, Jovan San Martin, Yixiong Lin, Xiaolin Zhu, Qian-Qian Zhang, Xiong-Wu Kang, Sui-Sui He, Yi-Xin Zhao, Xin Li, Li Niu, Dong-Dong Qin, Yong Yan, Dong-Xue Han〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Bi〈sub〉2〈/sub〉S〈sub〉3〈/sub〉 is a n-type (negative type) semiconductor that has a narrow band gap and an ideal band edge position for hydrogen generation. However, high charge recombination rate, low photoelectrochemical (PEC) efficiency and poor stability are of major concerns of Bi〈sub〉2〈/sub〉S〈sub〉3〈/sub〉 as a photoelectrode. Herein, we report an efficient Vanadium-rich Bi〈sub〉2〈/sub〉S〈sub〉3〈/sub〉 nanowires (atomic ratio of V to Bi is 1/22) that have been prepared on fluorine-doped tin oxide (FTO) substrate by an in-situ solution-processed reaction with BiVO〈sub〉4〈/sub〉 film as precursor. The resulting V-rich photoelectrode demonstrates notably high charge separation efficiency and fast charge transport with respect to pristine Bi〈sub〉2〈/sub〉S〈sub〉3〈/sub〉 nanowires. As a result, the photocurrent density of ca. 10 mA·cm〈sup〉-2〈/sup〉 at -0.2 V vs Ag/AgCl is obtained under visible light illumination. In addition, V-rich Bi〈sub〉2〈/sub〉S〈sub〉3〈/sub〉 generates IPCE (incident photocurrent-to-current conversion efficiency) of 50% at 460 nm and 45% at 760 nm, demonstrating a 2.0 and 2.8-fold increase, respectively, when compared with pristine Bi〈sub〉2〈/sub〉S〈sub〉3〈/sub〉. This enhancement is probably due to increased light absorption, less charge recombination, and faster charge transfer. More importantly, in contrast to pristine Bi〈sub〉2〈/sub〉S〈sub〉3〈/sub〉 sample that suffers detrimental photocorrosion in sulfide containing electrolyte, V-rich Bi〈sub〉2〈/sub〉S〈sub〉3〈/sub〉 nanowires retain 84.6% of its initial photocurrent over the course of 1 h. These findings are expected to shed light on engineering high-performance and robust metal sulfide materials for photoelectrochemical application.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304298-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈p〉Highlights〈/p〉 〈/div〉

Description: 〈p〉Publication date: Available online 16 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Mathias Barreau, Xavier Courtois, Fabien Can〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Selective Catalytic Reduction (SCR) is one of the most efficient process for NO〈sub〉x〈/sub〉 removal from Diesel exhaust gas. However, the urea/NH〈sub〉3〈/sub〉-SCR process implemented in recent vehicles still suffers from a poor activity in the low temperature range (T 〈 250°C). One main reason is its dependency against the NO〈sub〉2〈/sub〉/NO〈sub〉x〈/sub〉 ratio, limiting the expected fast-SCR reaction in this temperature range. Recently, we shown that the addition of ethanol to ammonia led to a significant increase of the activity of a Ag/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 catalyst in this low temperature range. Moreover, in a dual-bed configuration (Ag/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉+WO〈sub〉3〈/sub〉/Ce〈sub〉x〈/sub〉-Zr〈sub〉y〈/sub〉O〈sub〉2〈/sub〉), a remarkable improvement was achieved at low temperature using only NO as NO〈sub〉x〈/sub〉. The present work aims to highlight the DeNO〈sub〉x〈/sub〉 chemistry encountered over the WO〈sub〉3〈/sub〉/Ce〈sub〉x〈/sub〉-Zr〈sub〉y〈/sub〉O〈sub〉2〈/sub〉 catalyst in a bifunctional (EtOH+NH〈sub〉3〈/sub〉) mixture. In addition to the fact that this process takes advantage of the low temperature NO〈sub〉2〈/sub〉 formation over the upstream Ag/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 catalyst, this work also puts in evidenced unexpected interactions between NO〈sub〉2〈/sub〉 and CH〈sub〉3〈/sub〉CHO (resulting from ethanol oxidation over Ag/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉) thus leading to NO emission.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304407-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 15 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Jorge E. Ramos-Sanchez, R. Camposeco, Soo-Whon Lee, Vicente Rodríguez-González〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉SrTiO〈sub〉3〈/sub〉-cubic-like photocatalysts with average size of 35–40 nm were synthesized in 2 h without further calcination treatment. Structural defects or contamination were negligible according to the DRX and FTIR analyzes. The H〈sub〉2〈/sub〉 generation rates were 386 and 463 μmol h〈sup〉−1〈/sup〉 g〈sup〉〈sub〉−〈/sub〉1〈/sup〉 using an ethanol-water scavenger suspension with the SrTiO〈sub〉3〈/sub〉 and Ag/SrTiO〈sub〉3〈/sub〉 oxides, respectively. In comparison with other works reported in the literature, the hydrothermal synthesis of SrTiO〈sub〉3〈/sub〉 and the UV-pen lamp radiation used for the H〈sub〉2〈/sub〉 production may open a new strategy for the sustainable synthesis of 3-dimensional photoactive nanomaterials. The functionalization of nanocubes with highly monodispersed silver or rhodium nanoparticles provided an additional increase in the hydrogen photoproduction rate. In this sense, the silver nanoparticles (AgNPs) act as a sink for the photogenerated electrons through a Schottky barrier in the metal-perovskite contact region, boosting up the separation of the charge carriers. The identification of the surface species by XPS as well as the Rhodamine B photo-oxidation were performed to better understand the surface backward reaction in the photocatalytic production of hydrogen. The AgNPs worked as co-catalysts, preserving the stability of the most photoactive catalysts for 32 h.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304419-ga1.jpg" width="244" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 31 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Mun Kyoung Kim, Woo Hyeong Sim, Miri Choi, Hyungseob Lim, Youngkook Kwon, Hyung Mo Jeong〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Alkali metal ion intercalation into TiO〈sub〉2〈/sub〉 photocatalysts is a well-known method for obtaining enhanced photocatalytic properties. Herein, an effective electrochemical lithiation method is proposed for the synthesis of lithium-intercalated TiO〈sub〉2〈/sub〉 nanoparticles (NPs) suitable for high performance photocatalytic production of hydrogen. The electrochemical lithiation of TiO〈sub〉2〈/sub〉 induces partial reduction of Ti ions in the crystal lattices, which introduces additional energy states within the band edge of TiO〈sub〉2〈/sub〉, resulting in the improved optical properties. Consequently, Li-intercalated TiO〈sub〉2〈/sub〉 NPs exhibit almost 60-times improved hydrogen generation activity under both UV and visible light exposure compared to those of commercial TiO〈sub〉2〈/sub〉 NPs (P25).〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304195-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 31 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Gilliani Peixoto Miranda, Virgílio José Martins Ferreira Neto, Alexandre Ferreira Young, Erika Batista Silveira, Paulo Gustavo Pries de Oliveira, Fabiana Magalhães Teixeira Mendes〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Catalysts containing V-Mg-O species supported on activated carbon (AC), obtained from sugar-cane straw, were prepared and evaluated in the propane ODH reaction. Two conditions containing different molar amounts of Mg and V where prepared, one (condition II) with higher molar amounts of magnesium and vanadium than condition I, but the ratio of Mg/V = 1:2 was kept constant. For comparison purposes, the same preparation methodology was used but with MCM-41 as support, instead. The physicochemical properties of these catalysts were investigated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Laser Raman spectroscopy (RS) and Scanning electron microscopy, coupled with energy dispersive microscopy (SEM-EDS). For the first time the nature of V-Mg-O species on an activated carbon surface was investigated. The electron environment around vanadium was evaluated by XPS, revealing the coexistence of V〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 crystallites with highly dispersed species of Mg-V-O and P-V linkages on the surface. Vanadium enrichment was observed on the surface of those supported on activated carbon, especially for the preparation containing higher amounts of V and Mg. All the AC and MCM-41 supported catalysts were active and selective in ODH of propane into propylene and were stable for, at least 24 h, of reaction. The stability was attributed to the presence of the Mg-V linkages at the catalysts surface, while Phosphate CPO groups still exists, despite of the formation of V-P linkages.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304213-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 30 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Jing Ning, Yan Zhou, Aling Chen, Yong Li, Shu Miao, Wenjie Shen〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Cu species in the forms of layers, clusters and particles were dispersed on a rod-shaped ceria by a deposition-precipitation method and the resulting Cu/CeO〈sub〉2〈/sub〉 catalysts were tested for the low-temperature water-gas shift reaction. The structural, chemical and surface properties of the Cu/CeO〈sub〉2〈/sub〉 catalysts were analyzed by spectroscopic and microscopic techniques. It was identified that dispersion of copper on the rod-shaped ceria strongly depended on the metal loading (1–28 mol%): lower contents resulted in copper monolayers and/or bilayers while higher loadings led to multi-layered clusters and faceted particles. The copper-ceria interface was constructed by an intimate bonding of positively-charged copper atoms with oxygen vacancies on ceria, in a form of Cu〈sup〉+〈/sup〉-O〈sub〉v〈/sub〉-Ce〈sup〉3+〈/sup〉, involving the electronic and geometric interactions between the copper atoms in the metal species and the oxygen vacancies on ceria. The overall activity increased linearly with the copper content in the range of 1–15 mol%, contributed mainly by copper monolayers and/or bilayers. Further increasing Cu loading up to 28 mol% only slightly enhanced the activity because of the presence of multilayered and crystalline Cu particles. This finding demonstrates that the dispersion of copper on the rod-shaped ceria depends on the loading of copper in the Cu/CeO〈sub〉2〈/sub〉 catalysts, which is associated with the number and density of the active sites.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304043-ga1.jpg" width="450" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Fayan Zhu, Wenqian Zhang, Hongyan Liu, Xiufang Wang, Yongquan Zhou, Chunhui Fang, Yunhong Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, ion pairs in a single sodium tetrahydroxyborate [Na [B(OH)〈sub〉4〈/sub〉] droplet were analyzed using an “in-situ strategy” in which a sample-droplet of nanogram mass was deposited on a hydrophobic substrate and droplet was forced to enter into a supersaturated state by decreasing the relative humidity (RH) of the environment. The structure of the solvated [B(OH)〈sub〉4〈/sub〉〈sup〉−〈/sup〉] ionic moiety with various molar water-to-solute ratios (WSR) was analyzed using Raman spectroscopy. To confirm the structural changes in the droplet, electronic structure calculations were carried out using density functional theory (DFT). The frequencies calculated for the totally symmetric BO stretching vibration (〈em〉v〈/em〉〈sub〉sym(BO)〈/sub〉) of the [B(OH)〈sub〉4〈/sub〉〈sup〉−〈/sup〉] moiety were compared with those of the fundamental bands observed in the Raman spectra recorded of the droplets. The following results have been obtained: (i) when WSR is reduced from 9 to 0.1, the frequency of the band that corresponds to 〈em〉v〈/em〉〈sub〉sym(BO)〈/sub〉 shifts from 745 to 746 cm〈sup〉−1〈/sup〉, and its full-width at half-maximum value increases from 19.7 to 20.5 cm〈sup〉−1〈/sup〉; (ii) when WSR ≥7, the solvent-shared ion pair (SIP) is predominantly present in the solution, whereas in the case of WSR 〈 7, SIP transforms into a contact ion pair (CIP) formed by Na〈sup〉+〈/sup〉 and [B(OH)〈sub〉4〈/sub〉〈sup〉−〈/sup〉] in bidentate coordination; (iii) when WSR = 3, most of the CIPs transform into a cationic type of triple ion pair (TIP) composed of two Na〈sup〉+〈/sup〉 and one [B(OH)〈sub〉4〈/sub〉〈sup〉−〈/sup〉] in bidentate coordination; (iv) when WSR is further reduced, most TIP continually associate to form a more complex structure and with a small amount of six-membered ring complex also formed. These results will help us understand the ion association mechanism during dehydration process of Na[B(OH)〈sub〉4〈/sub〉] droplets.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519306985-ga1.jpg" width="426" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Zheng Fei Liu, Xue Chen, Wen Xin Wu, Gui Qi Zhang, Xin Li, Zhen Zhen Li, Wei Jun Jin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Room temperature phosphorescence (RTP) materials have become a hot topic in fields of organic light-emitting dioes, biological sensing and imaging. The present work reports firstly that 1,3,5-trifluoro-2,4,6-triiodobenzene (TITFB) can act as a simple pure organic NIR phosphor due to its novel function in promoting n-π* transition. Also, TITFB crystal has longer phosphorescence lifetime than other ordinary multiiodoluminophors and TITFB powder. Based on the TITFB crystal structure, σ-hole and π-hole capture mechanism of n-electron is proposed, i.e., the excited state energy is decreased and n-electrons are stabilized to cause slower radiative decay rate due to the restriction of σ-hole and π-hole bond. Both computational and experimental studies support the mechanism. The new electron-capture mode is more conducive to understanding pure organic ultralong lifetime RTP.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉TITFB as a simple pure organic NIR phosphor from n-π* transition and σ- and π-hole capture state of excited electron.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308182-ga1.jpg" width="424" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Ashok Zachariah Samuel〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Physical properties of polymers (e.g. crystallinity, lamella thickness, thermodynamic properties etc.) can in principle be reliably estimated from their Raman spectral intensities by converting intensities to corresponding concentrations of conformers. However, such conversions are not straightforward due to the unknown scattering cross-sections. The study demonstrates that for several practical applications of Raman spectroscopy, a ratio of cross-sections can be used instead of the absolute values. A straight forwards method for accurately estimating ratio of scattering cross-section from variable temperature measurements is described here. In order to demonstrate its applicability, percent crystallinity (PC) of polyethylene has been directly estimated from Raman intensities without external calibration with other techniques. This general method can be applied to any polymer when there is a continuous change in composition of conformers over a range of temperatures.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308212-ga1.jpg" width="493" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Shargina Beegum, Y. Sheena Mary, Y. Shyma Mary, Renjith Thomas, Stevan Armaković, Sanja J. Armaković, Jan Zitko, Martin Dolezal, C. Van Alsenoy〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This article represents the spectroscopic and computational studies of two new pyrazine compounds. In order to establish the structure and functional nature of the compounds, we have employed Fourier transformed infrared (FT-IR) and Raman spectra, nuclear magnetic resonance (NMR) spectra, and ultraviolet (UV) absorptions and have compared them with the simulated computational spectra and found that they are in the agreeable range. Simulated hyperpolarisability values are used to obtain the nonlinear optic (NLO) activity of the compound, to be used in organic electronic materials. The charge transfer and related properties was investigated by the simulation of electronic spectrum with time dependent density functional theory (TD-DFT). Natural transition orbitals (NTO) provides information about which region of the molecules are more involved in the electronic transitions and the charge transfer properties for the lowest energy excitation have been analyzed on the basis of electron density variation. Molecular dynamics simulations provide information about the behavior of the molecule in solutions. Frontier orbital analysis and study of various reactivity descriptors like ALIE and Fukui provided deep knowledge on the reactivity side. Molecular docking has been also performed to investigate the interaction between title molecules and exhibits inhibitory activity against 〈em〉Pseudomonas aeruginosa〈/em〉 Enoyl-Acyl carrier protein reductase (Fabl).〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308042-ga1.jpg" width="334" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Ruixin Xu, Wei Hu, Yanchen Zhou, Xianyi Zhang, Shu Xu, Qingyuan Guo, Ping Qi, Lingling Chen, Xuezhen Yang, Fan Zhang, Like Liu, Lijuan Qiu, Jun Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Water soluble protein content (WSPC) is a parameter of great significance to the soybean food industry. So far, genetic studies and breeding practices have been limited by the lack of a rapid technique for the evaluation of WSPC. Near-infrared reflectance spectroscopy (NIRS) is widely applied for rapid quantification of many traits, including moisture, protein and oil content, and dietary fiber. The present study aimed to establish and evaluate a NIRS regression model for the rapid prediction of WSPC in soybean. Results showed that seed coat color had a profound impact on the accuracy of protein content prediction, whereas the seed coat itself deeply influenced protein determination. We established a partial least squares (PLS) regression model with 167 soybean samples whose seed coat had been removed. Based on multiplicative scatter correction and Savitsky-Golay transformation, the highest determination coefficient (R〈sup〉2〈/sup〉) was 0.831, and the relative predictive determinant was 2.417. Further analysis showed that seed roundness correlated negatively with WSPC (〈em〉r〈/em〉 = −0.59, 〈em〉P〈/em〉 〈 0.001) and greatly impacted PLS regression model prediction accuracy. The PLS model was suitable only for intact seeds whose coat had been peeled off, but not for broken seeds, soy powder, and green cotyledon soybean seeds. This study highlights the effect the seed coat has on soybean composition determination by NIRS. Moreover, the established PLS model for soybean WSPC determination could facilitate genetic studies and breeding.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519307905-ga1.jpg" width="170" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Yang-Zi Ouyang, Hai-Long Wu, Huan Fang, Tong Wang, Xiao-Dong Sun, Yue-Yue Chang, Yu-Jie Ding, Ru-Qin Yu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The matter of fluoroquinolone residues in various foods still arouses wide public concern nowadays. In the present work, the strategy of excitation-emission matrix (EEM) fluorescence data coupled with second-order calibration method based on alternating normalization-weighted error (ANWE) algorithm was used to determine ofloxacin, lomefloxacin and ciprofloxacin in milk powder, milk and beef. Owning the unique “second-order advantage”, the ANWE-assisted analytical method was proved to successfully and eco-friendly resolve the overlapped fluorescence spectra of multi-component in complex food matrixes without tedious pretreatment steps and sophisticated high-cost instrumentations. The feasibility of the proposed method was validated by experiments. The average spiked recoveries of three fluoroquinolones range from 82.6% to 110.5% with relative standard deviations lower than 7.4%, and the limits of detection range from 0.18 and 2.41 ng mL〈sup〉−1〈/sup〉. For further evaluation, analytical figures of merit such as sensitivity and selectivity, as well as the RSDs of intra-day (≦10.6%) and inter-day (≦9.4%) were calculated. The satisfactory analytical results demonstrated that the proposed strategy could be a competitive alternative for simple, rapid and simultaneous determination of multiple fluoroquinolones in animal-derived food samples.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308480-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Yiran Zhang, Peng Liu, Youping Li, Reggie Zhan, Zhen Huang, He Lin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Laser-induced fluorescence (LIF) is an effective technique for non-intrusive and on-line measurement of PAHs in sooting flames but it is still need further investigation due to the complexity of PAH fluorescence characteristics. Therefore, in-depth investigations on the fluorescence spectroscopy of PAHs with different molecular structures are relevant. In this study, we investigated the fluorescence spectrum characteristics of 13 gas-phase PAHs using LIF measurement and time-dependent density functional theory (TD-DFT) calculation. The experimental results showed that the fluorescence emission wavelengths increased with more aromatic (benzenoid) rings, but this relationship no longer existed when the PAH molecules contain the five-membered ring structures. The TD-DFT calculation showed that the fluorescence emission wavelength ranges of PAHs with different molecular structures were dominantly determined by the electronic structures of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) and their energy gaps. It was found that the saturated aliphatic branched chains (methyl and ethyl) only slightly influenced the LIF spectra, while the unsaturated aliphatic branched chains (ethenyl and ethynyl) caused remarkable redshifts. The TD-DFT results indicated that the aliphatic branched chains changed the electric structures of HOMO and LUMO of the core aromatic rings, and then influence the fluorescence emission wavelength ranges.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308406-ga1.jpg" width="355" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Lijuan Ma, Yang Li, Leting Lei, Jingqi Zeng, Jing Zhang, Yanjiang Qiao, Zhisheng Wu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Real-time process quality control of 〈em〉ramulus cinnamomi〈/em〉 (〈em〉cassia twig〈/em〉) is still a challenge in pharmaceutical industry. Rapid critical quality attribute (CQA) determination of 〈em〉ramulus cinnamomi〈/em〉 is essential for quality control. Microscale thermophoresis (MST) was used to investigate the CQA of 〈em〉ramulus cinnamomi〈/em〉 by the interaction with biomacromolecule. There was a good affinity between cinnamaldehyde and human serum albumin (HSA) with 〈em〉K〈/em〉〈sub〉a〈/sub〉 as 2.1722 × 10〈sup〉3〈/sup〉 mol/L. It was an excellent combination of similarity to ibuprofen with same binding force as discovered as hydrogen bond and van der Waals force. Furthermore, regarding cinnamaldehyde as CQA, on-line near-infrared was used to monitor pilot extraction process of 〈em〉ramulus cinnamomi〈/em〉 combined with high performance liquid chromatography (HPLC). Quantitative model was established with R〈sub〉pre〈/sub〉〈sup〉2〈/sup〉 as 0.9798 and RMSECV as 0.0993, suggesting the NIR model was so robust and accurate for pilot process quality control. This method provided a perfect guideline for rapid CQA determination and real-time process quality control of Chinese materia medica (CMM) based on a vital CQA.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308534-ga1.jpg" width="355" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 336〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 336〈/p〉 〈p〉Author(s): M.O. Guerrero-Pérez, R. López-Medina, E. Rojas-Garcia, M.A. Bañares〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A XANES study under reaction conditions has been performed with two different V-based catalytic systems, Mo-V-Nb-Te-O and V-Sb-O. For this study, an alumina-supported nanoscaled bulk catalyst has been used. In all cases XANES determined the average vanadium oxidation state during reaction. XANES also demonstrated that the nanosized phases are more dynamic, and able to participate in the redox catalytic cycle without significant changes either in their structure or in the overall vanadium oxidation state. Such a stability is also apparent under oxidizing conditions.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586117308350-fx1.jpg" width="419" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Shuoyang Zhang, Hui Chen, Ruiyun Li, Zhiguo Yu, Feng Lu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉As expired medical products can be repackaged and sold by unscrupulous counterfeiters, it is essential to find a rapid and convenient method for distinguishing expired and unexpired drugs. Standard detection methods such as high-performance liquid chromatography (HPLC) and thin-layer chromatography are complex, time-consuming, and require organic solvents (that are environmentally unfriendly). Additionally, the Pharmacopoeia publications do not include information about identifying expired drugs. In this study, we proposed a novel method for identifying expired medications based on Raman spectra and verified it using 〉20 types of expired (Old) and unexpired (New) drugs, each type from the same manufacturer. A portable Raman spectrometer was used to collect Raman spectra of all samples and the similarities between the Old and New drugs (S〈sub〉N-O〈/sub〉) were evaluated. Drugs with S〈sub〉N-O〈/sub〉 values 〈0.9 were classified directly as expired drugs. For drugs with S〈sub〉N-O〈/sub〉 values 〉0.9, the content of active pharmaceutical ingredient (API) might be so low (below or around 10 wt%) that its Raman signal is largely obscured by that of the excipients. In such cases, changes in the API content are undetectable using the portable instrument. Therefore, we adopted Raman mapping technology and established a virtual imaging map to locate areas of high API content. The similarities between the Old or New spectrum and that of the API (S〈sub〉O-A〈/sub〉 and S〈sub〉N-A〈/sub〉, respectively) were calculated after removing the signal from the excipients. Our novel methods provide a precise, rapid, convenient, and environmentally friendly way to identify expired drugs that is more effective than the standard HPLC assay.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Expired and unexpired drugs were discriminated by Raman spectrometer and mapping technology, combining generation of Virtual Imaging Map (VIM), and finding the most similar-to-API pixel (M point) before deduction of excipients.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519307978-ga1.jpg" width="454" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Lin Li, Juan Chen, Yang Li, Nan Song, Lulu Zhu, Zhiying Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Detecting NAA in food has drawn intense attention as it has imposed significant threat to people's health and the growth of food industry. Over the past few years, great importance has been attached to the application of copper nanomaterials as fluorescent probe to food and environmental detection. Here, the simple, rapid, cost effective and water soluble fluorescent copper nanoparticles were synthesized with chemical reduction sonochemical assisted method for highly selective and sensitive detection of α-naphthaleneacetic acid (NAA) by using 2-mercaptobenzothiazole (MBT) as a protecting agent and polyvinylpyrrolidone (PVP) as a stabilizing agent (MBT-PVP CuNPs). The resultant CuNPs has a spherical shape with an average diameter of 10–15 nm and strong fluorescent pink emission characteristic peak at 580 nm upon 334 nm excitation. Interestingly, upon the addition of NAA, the fluorescence of MBT-PVP CuNPs can be effectively quenched for the reason that NAA could interact with MBT via hydrogen bonding and conform copper-NAA clathrate with Cu〈sup〉+〈/sup〉 via coordination bond, which shows a good linearity in the range of NAA from 0.5 to 50 μM and with a detection limit of 9.6 nM. Moreover, the prepared probe has good selectivity for NAA detection over other co-existing molecules. It is worth mentioning that this method has been successfully applied to authentic comestible sample analysis and obtained satisfying and promising results, which indicates that this strategy is likely to have a promising application potential for NAA detection in the field of food safety.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308236-ga1.jpg" width="301" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Jenny Jeehan Nasr, Shereen Shalan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Five Selective, rapid and sensitive spectrofluorimetric methods were performed in this study for the simultaneous estimation of amlodipine besylate (AML) and atorvastatin (ATR) in their binary mixtures and combination polypills that are used for management of cardiovascular conditions. The first method depends on micelle-enhanced first derivative synchronous fluorimetric analysis (method I) and the other four methods are multivariate analysis techniques based on the use of factor-based calibration prediction methods comprising partial least squares (PLS), Principal Component Regression (PCR), genetic algorithm PLS (GA-PLS) and genetic algorithm PCR (GA-PCR). The synchronous fluorescence spectra of the solutions were measured at a constant wavelength difference; Δλ = 100 nm. The magnitudes of the peaks of the first derivative spectra (1D) were measured at 292 nm and 387 nm for ATR, and AML correspondingly. The multivariate models were constructed utilizing fifteen mixtures as a calibration set and ten mixtures as a validation set. The linearity of all the methods was in the concentration ranges of (0.1–4.0 μg mL〈sup〉−1〈/sup〉, 0.4–10.0 μg mL〈sup〉−1〈/sup〉) for AML and ATR, correspondingly. Statistical analysis revealed no significant difference between the proposed methods and the reference method. The validity of the proposed methods allows their suitability for quality control work. All the analysis settings were optimized and all the suggested procedures were applied productively for the determination of both drugs in synthetic mixtures, validation set, and combination polypills.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308200-ga1.jpg" width="276" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Sagar B. Yadav, Sumeet S. Sonvane, Nagaiyan Sekar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Novel Donor (D)-π-Acceptor (A) NLOphoric triphenylamine-imidazole based dye 〈strong〉9〈/strong〉 was designed, synthesized, and confirmed by Mass, 〈sup〉13〈/sup〉C NMR, and 〈sup〉1〈/sup〉H NMR analysis. Photophysical properties of 〈strong〉9〈/strong〉 were studied in solvents of different polarities and compared with analogues compounds 〈strong〉7〈/strong〉 and 〈strong〉8〈/strong〉. Phenonthroline acceptor based dye 〈strong〉9〈/strong〉 shows highly bathochromic shifted absorption and emission compared to dyes 〈strong〉7〈/strong〉 and 〈strong〉8〈/strong〉. Positive solvatochromism was noticed in 〈strong〉7〈/strong〉, 〈strong〉8〈/strong〉, and 〈strong〉9〈/strong〉 which was supported by the linear (i.e. Lippert-Mataga and Mac-Rae polarity functions) and multi-linear (i.e. Kamlet-Taft and Catalan parameters) analysis. Moreover, solvent polarizability (d〈sub〉SP〈/sub〉) and solvent dipolarity (C〈sub〉SdP〈/sub〉) are the major factors responsible for red shift in absorption as well as in emission spectra. Charge transfer descriptors as well as the polarity graphs are in good relation with Generalized Mulliken-Hush (GMH) parameters. NLO properties of 〈strong〉7〈/strong〉, 〈strong〉8〈/strong〉, and 〈strong〉9〈/strong〉 were studied by using solvatochromic and computational methods. The static first hyperpolarizability (β〈sub〉0〈/sub〉) and relevant microscopic parameters (μ,α〈sub〉0〈/sub〉,α,β,γ) were determined using DFT with B3LYP, BHHLYP, and CAM-B3LYP functionals. Third-order NLO properties of nitrogen containing phenanthroline based compound 〈strong〉9〈/strong〉 were observed to be several times higher than those of the compounds 〈strong〉7〈/strong〉 and 〈strong〉8〈/strong〉, justify the design approach.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S138614251930811X-ga1.jpg" width="415" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Xiaoming Dou, Yubin Zhao, Mingda Li, Qinmiao Chen, Yoshinori Yamaguchi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Raman microspectroscopy as a non-invasive and label-free technique was applied to diagnose the early stage differentiation of mouse embryonic stem cells. The differentiated and undifferentiated embryonic bodies (EBs) were cultured using handing drop method by the control of Leukemia Inhibitory Factor (LIF). Raman spectra of the periphery cells of differentiated EBs (PrE cells) and those of the interior of undifferentiated EBs (ES cells) were obtained to diagnose the stem cells of different differentiation. It was found from the spectra that the protein content increased as the cells differentiated. Principal component analysis (PCA) was carried out to further analyze the differences between ES cells and PrE cells. The first three principle components contained 98.19% from the total variance. Characteristic bands of ES and PrE cells were chosen to acquire Raman images of two cells according to the results of PCA. In the Raman images, PrE cells had a clear and bright outline in the peripheral areas while ES cells were difficult to identify, this could be a distinct characteristic to discriminate them. The result of the Raman images was consistent with the biological agreement that the differentiated cells were distributed around the periphery.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308285-ga1.jpg" width="301" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Miao Yu, Chun-Shan Zuo, Ning Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Rational design chelating fluorescent sensors probing metal ions in biological system are continuously hot essays nowadays, especially for zinc detection. Herein, a naphthylideneimine based zinc fluorescence probe (〈strong〉3〈/strong〉) was prepared and characterized in this work. Structural features and optical properties of 〈strong〉3〈/strong〉 and its metallic complexes were characterized. Fluorescent experiment indicates 〈strong〉3〈/strong〉 is extremely sensitive and selective for Zn〈sup〉2+〈/sup〉 with a strong fluorescence enhancement (~34 folds) in aqueous buffer solution with a limit of detection (LOD) of 3.78 × 10〈sup〉−7〈/sup〉 mol L〈sup〉−1〈/sup〉. Formation constant (log〈em〉K〈/em〉〈sub〉a〈/sub〉) of the chelating complex of 〈strong〉3〈/strong〉 and Zn〈sup〉2+〈/sup〉 ion was determined to be 4.45. Theoretical studies were carried out to get deep insight into the response mechanism in the sensing process. Density functional theory (DFT) methods calculated formation Gibbs free energy (Δ〈sub〉r〈/sub〉G〈sub〉m〈/sub〉〈sup〉ө〈/sup〉) of the deprotonated complexes model (〈strong〉3〈/strong〉〈sup〉2−〈/sup〉 〈strong〉⊃〈/strong〉 〈strong〉Zn〈/strong〉) is −2.9 kcal/mol, which is in good agreement with the experimental result. The calculation results show that the low excitation states can be ascribe to S0 → T2 and S0 → S1 at 390–430 nm and 310–330 nm, respectively, due to the π → π* transition. Finally, yeast cell imaging experiments indicate that 〈strong〉3〈/strong〉 can monitor intracellular Zn〈sup〉2+〈/sup〉 as well. These findings would enable this fluorescent probe to be used as a Zinc sensor.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519307796-ga1.jpg" width="434" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 20 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Arun Kumar, Nishith Verma〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Emerging organic pollutants and heavy metals are the most common co-contaminants in water bodies. Efficacy of the Cu-Fe bimetals-dispersed carbon nanofibers (CNFs) grown over activated carbon beads (ACBs) was investigated for remediation of wastewater co-contaminated with dichlorvos (DDVP) (pesticide) and toxic Cr(VI) at moderate temperature and pressure (200 °C and 25 bar) using air as an oxidant. The experimental data showed that ˜95 and 80% degradation of DDVP (single feed) was achieved in 3 h over Cu-CNF/ACB and Fe-CNF/ACB, respectively, whereas complete degradation was measured during the identical time over Cu-Fe-CNF/ACB. In case of mixed feed (DDVP and Cr), complete degradation of DDVP as well as reduction of Cr(VI) was achieved in only 1 h. DDVP was degraded or mineralized by the hydroxyl radicals (〈sup〉〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/rad"〉〈/sup〉OH) through oxidation, whereas Cr(VI) was reduced to Cr(III). Further analysis indicated that reduction of Cr(VI) to Cr(III) was facilitated by the transformed intermediate products of DDVP, which were recognized as the formic and acetic acids. Analysis of the spent water showed complete mineralization of DDVP with simultaneous reduction of Cr(VI) to Cr(III). The toxicity tests showed the spent water to be non-toxic. This is the first study to indicate the successful remediation of wastewater co-contaminated with a recalcitrant organic pollutant and a heavy toxic metal over the catalytic Cu-Fe-CNF/ACB.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉Simultaneous oxidation of DDVP and reduction of Cr(VI) to Cr(III) over Cu-Fe dispersed carbon nanofiberous catalytic beads in wet air.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304481-ga1.jpg" width="401" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Xilang Jin, Jingkai Gao, Ting Wang, Wan Feng, Rong Li, Pu Xie, Lele Si, Hongwei Zhou, Xianghan Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Herein, we presented two novel turn-on colorimetric and fluorescent probes based on a F〈sup〉−〈/sup〉 triggered Si〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉O bond cleavage reaction, which displayed several desired properties for the quantitative detection for F〈sup〉−〈/sup〉, such as high specificity, rapid response time (within 3 min) and naked-eye visualization. The fluorescence intensity at 574 nm (absorbance at 544 nm) of the solution was found to increase linearly with the concentration of F〈sup〉−〈/sup〉 (0.00–30.0 μM) with the detection limit was estimated to be 0.47 μM/0.48 μM. Based on these excellent optical properties, the probes were employed to monitor F〈sup〉−〈/sup〉 in real water samples and tea samples with satisfactory. Furthermore, it was successfully applied for fluorescent imaging of F〈sup〉−〈/sup〉 in living nude mice, suggesting that it could be used as a powerful tool to predict and explore the biological functions of F〈sup〉−〈/sup〉 in physiological and pathological processes.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308571-ga1.jpg" width="249" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 15 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Sang-Chul Jung, Heon Lee, Seo Jin Ki, Sun-Jae Kim, Young-Kwon Park〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Understanding the performance and mechanism of the degradation of various contaminants is essential for the effective design of wastewater treatment systems. This study examined the degradation of 1,4-dichlorobenzene in a photocatalytic system, which embedded TiO〈sub〉2〈/sub〉 particles (as a thin film) on alumina balls (as a solid support). Decomposition of the parent compound was assessed by introducing a TiO〈sub〉2〈/sub〉 photocatalyst, microwave irradiation, and ultraviolet irradiation jointly or separately (in terms of the system configuration) with and without an adjustment for the microwave intensity, pH, and hydrogen peroxide levels (in terms of the operating conditions) to the photocatalytic system. The results showed that the photocatalytic system adopting multiple processes concomitantly improved the degradation performance of the parent compound that was resistant to the single-unit processes. On the other hand, the decomposition efficiency was increased further with the sophisticated control of the operating conditions, specifically the pH and hydrogen peroxide levels. A dechlorination process as well as substitution and addition reactions involving the hydroxyl radical appeared to occur in the degradation pathway to produce four degradation products from the parent compound. The significance of this study lies in the introduction of a systematic approach to optimizing the operating conditions that facilitate the decomposition efficiency in a given photocatalytic system at no extra cost.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304420-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 13 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Zhou-jun Wang, Runduo Zhang, Zhigang Lei, Claude Descorme, Michael S. Wong〈/p〉

Description: 〈p〉Publication date: Available online 12 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Marina Godino-Ojer, Mariya Shamzhy, Jiři Čejka, Elena Pérez-Mayoral〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report here efficient synthesis of quinoxalines from o-phenylendiamine and α-hydroxy ketones over commercial Basolites. The concentration and type of acid centres, as CUS sites, together with the porosity of the samples strongly influence the resulting conversion and selectivity. Our results indicate that the formation of quinoxalines preferentially follows a new route, in which tautomerization reactions are also involved.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586119304237-ga1.jpg" width="256" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today, Volume 336〈/p〉 〈p〉Author(s): Casey P. O’Brien, Ivan C. Lee〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Pd and PdCu alloy membranes are promising candidates for separating hydrogen from mixed gas streams due in part to their infinite selectivity to hydrogen separation. However, other gases such as CO can inhibit hydrogen transport across Pd-based membranes. In this work, the mechanism by which CO inhibits hydrogen transport across a 25 μm-thick Pd〈sub〉47〈/sub〉Cu〈sub〉53〈/sub〉 (mol%) membrane is investigated by 〈em〉operando〈/em〉 infrared-reflection absorption spectroscopy (IRAS) in the 373–533 K temperature range. In the absence of hydrogen, CO adsorbs on three different sites on the PdCu surface: (1) bridging between contiguous Pd atoms, (2) on top of isolated Pd atoms surrounded by Cu atoms, and (3) on top of oxidized Cu atoms. CO induces agglomeration of isolated Pd atoms on the PdCu surface, which is driven by the higher stability of CO adsorbed on bridging sites between Pd atoms than on isolated Pd atoms surrounded by Cu atoms. The rate of hydrogen permeation across the PdCu alloy membrane decreases with increasing CO concentration in the feed gas, and the poisoning effect of CO is more severe at lower temperatures. CO inhibits hydrogen transport across the membrane by adsorbing only on Pd sites on the PdCu surface and blocking H〈sub〉2〈/sub〉 dissociation on these sites. Due to the weaker interaction of CO with PdCu alloy surfaces than with Pd, the PdCu alloy is more resistant to CO poisoning than pure Pd.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586117306545-fx1.jpg" width="454" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Yanjing Dong, Zikang Chen, Meirong Hou, Li Qi, Chenggong Yan, Xiaodan Lu, Ruiyuan Liu, Yikai Xu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Mitochondria are essential organelles in eukaryotic cells and act as the energy powerhouse and biosynthetic compartment. Fluorescent dyes are widely used powerful molecular tools for analytical sensing and optical imaging. Low photostability, short excitation and emission wavelengths, and aggregation-induced quenching effects restrict the application of traditional commercial mitochondrial fluorescent probes for bioimaging. In this study, using rhodamine as the acceptor and phenothiazine as the donor, we synthesized a novel mitochondrial-targeted near infrared (NIR) fluorescent probe, MIT-PZR. Due to low cytotoxicity, great photostability and high specificity for mitochondria targeting, MIT-PZR has enormous potential for cell imaging. Furthermore, with a sizeable Stokes shift (emission peak at 705 nm), MIT-PZR penetrated tissues providing stable red fluorescence for imaging 〈em〉in vivo〈/em〉. The histological assessment of various tissues after treatment with MIT-PZR indicated that it has good biocompatibility. Thus, MIT-PZR is a promising mitochondrial NIR fluorescent probe for future application in clinical diagnosis and modern biological research.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉An AIE-active, near-infrared fluorescent probe (MIT-PZR) based on an energy donor-acceptor (D-A)-type structure is explored for fluorescent visualization and detection of mitochondria in view of a large Stokes shift, NIR emission, excellent photostability, and mitochondria-targeted.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308467-ga1.jpg" width="310" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Aiqing Feng, Fangru Jiang, Guiyuan Huang, Peilian Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Anionic surfactants were widespread used in car cleaning agents, household detergents, agricultural and industrial processes, and considered as a major source of environmental pollutant. Therefore, it is necessary to develop a fast, simple, highly selective and sensitive probe for the detection of anionic surfactants. Here, we synthesized two aggregation induced emission (AIE)-active molecules 4,4′,4″,4‴-(ethene-1,1,2,2-tetrayltetrakis(benzene-4,1-diyl))tetrakis (1-(4-bromobenzyl)pyridin-1-ium) bromide (〈strong〉TPE〈/strong〉-〈strong〉Br〈/strong〉) and 4,4′,4″,4‴-(ethene-1,1,2,2-trayltetrakis(benzene-4,1-diyl))tetrakis(1-methylpyridin-1-ium)iodide (〈strong〉TPE〈/strong〉-〈strong〉I〈/strong〉), which were then applied as fluorescence probes for detecting sodium dodecyl sulfate (SDS) with high selectivity and sensitivity. In the presence of SDS, a multi-fold fluorescence emission intensity enhancement was observed in both two probes (〈strong〉TPE〈/strong〉-〈strong〉Br〈/strong〉 and 〈strong〉TPE〈/strong〉-〈strong〉I〈/strong〉) due to the electrostatic self-assembly of AIE molecular. The limits of detection are 71.5 and 120 nM for 〈strong〉TPE〈/strong〉-〈strong〉Br〈/strong〉 and 〈strong〉TPE〈/strong〉-〈strong〉I〈/strong〉, respectively. This study may provide a new strategy for environmental monitoring by AIE-based fluorescent probe.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Two cationic fluorescent probes (〈strong〉TPE-Br〈/strong〉 and 〈strong〉TPE-I〈/strong〉) were designed and synthesized for detecting sodium dodecyl sulfonate (SDS) with high selectivity and sensitivity. In the presence of SDS, a multi-fold fluorescence emission intensity enhancement was observed in the both of two probes due to the electrostatic self-assembly of AIE molecular.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308364-ga1.jpg" width="404" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Xueqin Jiang, Zengjin Liu, Youzhe Yang, Hao Li, Xiaoyi Qi, Wen Xiu Ren, Mingming Deng, Muhan Lü, Jianming Wu, Sicheng Liang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A novel two-photon pH probe, 3-benzimidazole-7-hydroxycoumarin (〈strong〉BHC〈/strong〉), was designed and synthesized based on the structures of hydroxycoumarin and benzimidazole. 〈strong〉BHC〈/strong〉 showed good linearity in the pH ranges of 3.30–5.40 (pKa = 4.20) and 6.50–8.30 (pKa = 7.20) at a maximum emission wavelength of 480 nm. 〈strong〉BHC〈/strong〉 in acidic and alkaline media could be distinguished by an obvious spectral shift of the maximum absorption wavelength from 390 nm to 420 nm. In addition, 〈strong〉BHC〈/strong〉 was well localized to mitochondria and successfully applied to one-photon and two-photon imaging of pH changes in the mitochondria of HeLa cells. The findings presented herein suggest that 〈strong〉BHC〈/strong〉 can serve as an excellent fluorescent probe for selectively sensing mitochondrial pH changes with remarkable photostability and low cytotoxicity.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S138614251930825X-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Manuel J. Schuler, Raphael Henn, Christian G. Kirchler, Inge Schlapp-Hackl, Christian W. Huck, Thomas S. Hofer〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉In this article the extension of the grid-based Numerov approach to probe two coupled, localised vibrational modes is assessed. The theoretically obtained wave numbers are compared to experimental results for five increasingly complex organic molecules carrying two OH groups measured in gas-phase as well as carbon tetrachloride. By using an appropriate spacing of the associated potential energy grid a deviation of the predicted wave numbers with experiment of ≤1% is achieved for both the fundamental and the first overtone bands. In particular the calculated wave numbers of aliphatic species in vacuum underline the versatility of this approach. In addition, it is demonstrated that bicubic interpolation is a viable strategy to greatly reduce the required data points and thus, the computational effort. Comparison of predicted wave numbers obtained for different conformers with experimental data enables the identification of the most relevant conformer present in solution.〈/p〉 〈p〉Since especially the accurate calculation of overtone vibrations is known to be challenging in case of strongly anharmonic potentials such as OH bonds, the presented approach provides a particularly efficient route to study the properties of the associated overtone contribution under the influence of inter-mode coupling. This is due to the fact that the Numerov approach requires no assumption about form and composition of the vibrational wave functions. In addition, the presented method also provides one of the simplest routes to access combined excitations of the considered vibrational modes.〈/p〉 〈/div〉 〈h5〉Graphical Abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S138614251930767X-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Mahmoud M. Sebaiy, Sobhy M. El-Adl, Amr A. Mattar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Six simple, specific, accurate and precise spectrophotometric methods were developed for the first time analysis of some co-administered drugs with paracetamol in their mixture form without prior separation. Paracetamol & orphenadrine citrate were determined by using dual wavelength, bivariate, ratio difference, ratio derivative and mean centering of ratio spectra methods. Paracetamol & caffeine were determined by using ratio difference, ratio derivative and mean centering of ratio spectra methods. Paracetamol & diclofenac sodium were determined by using advanced absorption subtraction, ratio difference, ratio derivative and mean centering of ratio spectra methods. All of these methods were validated according to ICH guidelines where accuracy, precision, repeatability and robustness were found to be within the accepted limits. Advantages and limitations of each method are demonstrated and statistical comparison between the proposed methods was performed.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉Six spectrophotometric methods can be used to resolve the overlapping of some co-administered drugs with paracetamol such as paracetamol & orphenadrine citrate, paracetamol & caffeine and paracetamol & diclofenac sodium.〈/p〉 〈p〉Overlapping spectra of some co-administered drugs with paracetamol.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308194-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Shutao Wang, Junzhu Wang, Fengkai Shang, Yutian Wang, Qi Cheng, Na Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this paper, we have proposed a method to detect a mixture of carbamate pesticides using a back propagation network (BP), which is optimized by genetic algorithm (GA) for quantitative analysis. This method aims to combine the advantages of BP and GA to remedy their drawbacks. The training samples were taken as input, some performance indexes such as the predicted values, iteration time, mean squared error, correlation coefficient and recovery rate were compared between BP neural network and the constructed GA-BP model to evaluate the performance of two neural networks. Results show that the optimized GA-BP model can effectively predict the concentrations, the mean squared error and recovery rate are better. In addition, the correlation coefficient has a significant improvement. This study can provide a new way for detection of the pesticides mixture and help to analysis in a reliable way.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519307863-ga1.jpg" width="247" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Zhao Mu〈sup〉a〈/sup〉, Jianhao Hua〈sup〉a〈/sup〉, Yaling Yang〈sup〉a〈/sup〉〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The application of fluorescent carbon dots in bio-imaging has huge positive significance in the field of biomedicine. By taking this advantage, herein we prepared nitrogen, sulfur and iodine doped carbon dots (N,S,I-CDs) by a facile hydrothermal reaction using C〈sub〉3〈/sub〉N〈sub〉3〈/sub〉S〈sub〉3〈/sub〉, potassium iodate (KIO〈sub〉3〈/sub〉) and ethylenediamine (EDA), and the obtained N,S,I-CDs show bright blue fluorescence with a high fluorescence quantum yield of about 32.4%. The prepared N, S, I-CDs could interact with the folic acid (FA) with high selectivity, lead to development of a high sensitive method for the FA detection from 0.1 to 175 μM wide linear range with a detection limit of 84 nM (S/N = 3) and also applied them in U-2 OS cells imaging. Moreover, this sensor possessed a good sensitivity, linearity and reversibility in the temperature range of 10–80 °C, and successfully applied for the temperature sensing in cell HT-29 samples. This investigation illustrates that as-prepared N, S, I-CDs probe may have great potential as a high-performance platform for the accurate recognition of temperature in cells and could provide a new tool for the detection of FA in cells.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308340-ga1.jpg" width="347" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Yong Du, Yaguo Wang, Jiadan Xue, Jianjun Liu, Jianyuan Qin, Zhi Hong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In order to characterize molecular structures of 2,4,6-trihydroxybenzoic acid (PCA) by means of vibrational spectroscopic techniques, we report investigation of PCA monohydrated form and its anhydrous polymorphic one by using terahertz and Raman spectral characterization. The experimental THz spectra show that the monohydrated PCA only has two absorption bands at 0.69 and 1.65 THz respectively in the frequency region from 0.2 to 1.8 THz, meanwhile the anhydrous form has a few significantly different absorption bands at 0.75, 1.01, 1.46 and 1.64 THz, respectively. Furthermore, Raman spectra characterized such differences of vibrational modes shown within 200–1800 cm〈sup〉−1〈/sup〉 region about the monohydrated and anhydrous forms of PCA. In view of various possible theoretical structural forms that may exist in anhydrous PCA and its monohydrated one, density functional theory calculations were performed to simulate optimized structures and vibrational mode of above two PCA polymorphic forms. Theoretical results and experimental THz/Raman spectra of anhydrous PCA show that the dimer synthon via the carboxylic group ••• carboxyl group and its ortho-phenolic hydroxyl group inter-molecular hydrogen bonding interaction establishing the theoretical form I (AH-I) is more consistent with experimental observation than other theoretical forms (AH-II and AH-III). Meanwhile, the theoretical monohydrated form I (MH-I), which is formed by the linkage of carboxyl group and its ortho-phenolic hydroxyl group with water molecule, is also much more agreement with experimental spectral observations of PCA monohydrate than other monohydrated forms (MH-II and MH-III). Our study demonstrates effectively qualitative analysis of both micro-molecular structures and dehydrated transitions between anhydrous and hydrated polymorphic forms of PCA, thus providing rich information on the corresponding structural changes of anhydrous and hydrated PCAs due to various inter-molecular and intra-molecular interactions based on their finger-print vibrational spectra combined with theoretical simulations.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308261-ga1.jpg" width="335" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Yan Chen, Yongzhe Piao, Xia Feng, Xi Yu, Xiaoning Jin, Guangjiu Zhao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, density functional theory (DFT) and time density functional theory (TDDFT) methods were employed to investigate the nature of the double fluorescence emission of DEAHF in these three solvents. We analyzed the geometric structures, vibrational frequencies, frontier molecular orbitals (MOs), molecular electrostatic potential surface (MEPS), calculated absorption and fluorescence spectra and the potential-energy curves for DEAHF. All the results show that the intramolecular hydrogen bond of DEAHF is strengthened from S〈sub〉0〈/sub〉 to S〈sub〉1〈/sub〉 and the electron density redistribution occurs between the proton acceptor and donor, which can facilitate ESIPT. Moreover, the geometric structures, absorption and emission spectra, MEPS and potential-energy curve of DEAHF are identical. It reveals theoretically that ACN and PC can maintain the polarity of the solvent with 1:1 mixing, which is consistent with the experimental results.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308066-ga1.jpg" width="361" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Qisheng Deng, Zece Zhu, Xuewen Shu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Molecular motion plays an important role in the reverse intersystem crossing of thermally activated delayed fluorescence (TADF) materials, since the conformation varies as the molecule vibrates, leading to potential changes in the energies of excited states. Although many theoretical simulations have researched the relationship between the excited states and the molecular conformations, there are still few experimental results showing the energy level difference between different long-lived excited states. Herein, a novel method for measuring spectrally resolved luminescence lifetimes is proposed to detect the energy splitting of the long-lived excited states of a classical TADF molecule, BTZ-DMAC. A set of the time-gated luminescence spectra with different delay times were captured by a spectrograph equipped on an auto-phase-locked system, and then used for lifetime analysis at each wavelength. Unlike traditional measurement techniques, the proposed novel method does not require ultrafast laser, high-speed detector and any phase matching circuitry, thus significantly reducing the cost. This method revealed a definite energy gap between the two excited states of BTZ-DMAC with different lifetimes, indicating different conformations caused by molecular vibration. This low-cost method could be also used to detect many other luminescence materials for investigating the detail mechanisms of multiple excited states.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308248-ga1.jpg" width="344" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 224〈/p〉 〈p〉Author(s): Israa Zeid, Rania Al Abdallah, Nayla El-Kork, Mahmoud Korek〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉By the use of the ab initio CASSCF/(MRCI+Q) calculations in the representation 〈sup〉2s+1〈/sup〉Ʌ〈sup〉(+/−)〈/sup〉, the adiabatic potential energy curves and the dipole moment curves of the low lying states of the alkaline earth hydride anions (MgH〈sup〉−〈/sup〉, CaH〈sup〉−〈/sup〉, SrH〈sup〉−〈/sup〉 and BaH〈sup〉−〈/sup〉) have been investigated in their singlet and triplet multiplicities. The spectroscopic parameters T〈sub〉e〈/sub〉, R〈sub〉e〈/sub〉, ω〈sub〉e〈/sub〉, B〈sub〉e〈/sub〉, α〈sub〉e〈/sub〉, the dipole moment μ〈sub〉e〈/sub〉, and the dissociation energy D〈sub〉e〈/sub〉 have been also calculated for the bound states of the considered molecules. In addition, a systematic investigation of the transition dipole moment curves for the lowest 〈sup〉1〈/sup〉Σ〈sup〉+〈/sup〉-〈sup〉1〈/sup〉Π transitions has been done along with the Franck-Condon factor (FCF) corresponding to the X〈sup〉1〈/sup〉Σ〈sup〉+〈/sup〉-(1)〈sup〉1〈/sup〉Π transition. Using the canonical function approach, a rovibrational study has been performed for finding the rovibrational constants E〈sub〉v〈/sub〉, B〈sub〉v〈/sub〉, D〈sub〉v〈/sub〉 and the turning points R〈sub〉min〈/sub〉 and R〈sub〉max〈/sub〉 for the ground and different excited bound state. Efficient routes may be achieved via the diagonal FCF for the formation of cold and ultracold alkaline earth hydride anions.〈/p〉〈/div〉 〈div〉 〈h6〉PACS N〈sup〉o〈/sup〉 〈/h6〉 〈p〉31.10. + z, 31.15.A, 31.15.vn, 31.50.Df.〈/p〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉For the alkaline earth hydride molecular anions XH〈sup〉−〈/sup〉 (X = Mg, Ca, Sr and Ba), the potential energy curves in the representation 〈sup〉2s+1〈/sup〉Λ〈sup〉(+/−)〈/sup〉 have been calculated along with the spectroscopic constants, the static and transition dipole moment, the Franck-Condon factor and the rovibrational calculations of the investigated electronic states.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1386142519308510-ga1.jpg" width="357" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉