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  • 1
    Publication Date: 2020-08-25
    Description: Natural polyphenols contained in olive mill wastewaters (OMW) have been usually associated with great bioactive properties as “antioxidants”. In this work, we recovered the polyphenols after adsorption onto natural clay “ghassoul” by different solvents: water, ethyl acetate, and methanol (PPW, PPA, and PPM, respectively) to avoid environmental pollution. Also, we tested the antioxidant activity of the extracted polyphenols by two methods: 1,1-diphenyl-2-picrylhydrazyl (DPPH) and total antioxidant capacity (TAC). Then, we analyzed antimicrobial activity by the microdilution technique to determine at the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). The OMW of the Fez-Meknes region has a very acidic pH, considerable amounts of mineral matter, and a high concentration of polyphenols and organic content. The results of the test from DPPH showed good antiradical potential for polyphenols extracted with water, but the TAC showed an important capacity for all extracts unless PPA. The antibacterial activity is not the same on the four bacteria studied (Escherichia coli, Salmonella sp, Staphylococcus aureus, and Enterococcus faecalis), and all extracts inhibit most tested germs that do not have the same MIC and the same sensitivity. Only the PPW showed the minimum bactericidal concentration (MBC) that is equal to 0.290 mg/mL for Salmonella sp and Staphylococcus aureus, which confirms that the extraction by water of the adsorbed polyphenols is an original solution to recover the polyphenols and also to obtain a natural phenolic antioxidant which can be used in the pharmaceutical, nourishment, and cosmetic industry.
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  • 2
    Publication Date: 2020-08-27
    Description: This paper aims to improve the metallurgical properties of vanadium-titanium magnetite (VTM) concentrates pellets by applying solid waste containing B2O3. Thus, the effects of adding B2O3 on the drop strength, compressive strength, pores area ratio, high-temperature metallurgical properties, and microstructure of VTM pellets were studied through pelletizing and roasting experiments. Results show that the addition of B2O3 reagent is not conducive to the increase of the drop strength of the green pellets. Nevertheless, the compressive strength and fracture toughness of the roasted pellets can be improved by adding more B2O3 during the pelletizing. The reduction degree of VTM pellets is firstly decreased and then increased with the added B2O3 amount. It is possible to improve the compaction degree and restrain the reduction-pulverization degree of the pellet by a low amount of additive (B2O3). The reduction-expansion performance of VTM pellets, in turn, can be raised by adding B2O3.
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  • 3
    Publication Date: 2020-08-30
    Description: The use of sunlight for photocatalytic oxidation is an ideal strategy, but it is limited by factors such as insufficient light absorption intensity of the photocatalyst and easy recombination of photogenerated electron holes. TiO2 is favored by researchers as an environment-friendly catalyst. In this paper, TiO2 is combined with WO3 to obtain a nanofiber with excellent catalytic performance under sunlight. The WO3/TiO2 composite nanofibers were synthesized by using the electrospinning method. The X-ray diffraction (XRD) analysis indicated that WO3 was successfully integrated onto the surface of TiO2. The photodegradation performance and photocurrent analysis of the prepared nanofibers showed that the addition of WO3 really improved the photocatalytic performance of TiO2 nanofibers, methylene blue (MB) degradation rate increased from 72% to 96%, and 5% was the optimal composite mole percentage of W to Ti. The scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectra (UV-Vis DRS), and Brunauer-Emmett-Teller (BET) analysis further characterized the properties of 5% WO3/TiO2 nanofibers. The H2 generation rate of 5% WO3/TiO2 nanofibers was 107.15 μmol·g−1·h−1, in comparison with that of TiO2 nanofibers (73.21 μmol·g−1·h−1) under the same condition. The 5% WO3/TiO2 produced ·OH under illumination, which played an important role in the MB degradation. Also, the enhanced photocatalytic mechanism was also proposed based on the detailed analysis of the band gap and the active species trapping experiment. The results indicated that the effective separation of Z-scheme photogenerated electron-hole pairs and transfer system constructed between TiO2 and WO3 endowed the excellent photocatalytic activity of 5% WO3/TiO2 nanofibers.
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  • 4
    Publication Date: 2020-07-15
    Description: Unripe plantain has been considered as having commercial potential or used as an ingredient for other foods. Information on the physicochemical and carotenoid properties of flours from hybrid plantain cultivars in the literature is limited. This study was conducted to determine the physicochemical properties and carotenoid contents of unripe plantain flour from selected hybrid plantain cultivars using standard laboratory methods. The unripe plantain pulps of four varieties (PITA 26, PITA 27, Mbi Egome and Agbagba (control)) used in this study were cabinet dried at 65°C for 48 h and milled into flour. The result showed that moisture content ranged from 6.15 to 7.27%, Ash (2.01–3.69%), Fat (0.49–1.20%), Protein (2.47–2.99%), Fibre (0.73–0.97%), Sugar (6.29–9.33%), starch (84.34–104.96%), total carotenoid content (2.96–24.19 µg/g). Potassium ranged from 328.30–528.50 mg/kg, Calcium (9.46–11.98 mg/kg), Magnesium (24.73–29.11 mg/kg), Sodium (6.30–7.24 mg/kg), Zinc (0.12–0.29 mg/kg), and manganese (0.03–0.15 mg/kg). The L∗ (Lightness) ranged from 62.88 to 67.00. Bulk density ranged from 0.72 to 0.77 g/ml, WAC (143.59–174.08), OAC (98.07–100.66%), swelling power capacity (10.63 to 11.82%), solubility (5.58–6.71%), and dispersibility (86.50–88.00%). Peak viscosity ranged from 568.17 to 761.64 RVU, final viscosity (378.53–496.58 RVU), and peak temperature (81.62–83.23°C). The results suggest that the hybrid plantain cultivars could be used to produce good quality plantain flours with improved physicochemical and pasting properties.
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  • 5
    Publication Date: 2020-07-15
    Description: Nanosuspensions are widely reported to enhance the solubility of poorly soluble drugs. In addition to enhancement in solubility, improvement of stability and therapeutic efficacy would be an added advantage. In the present study, premilling and subsequent high-pressure homogenization were carried out to produce naringenin nanosuspension. Hydroxypropyl methylcellulose and sodium dodecyl sulfate were evaluated for their performance as stabilizers under various homogenization cycles. The prepared nanosuspensions were studied for average particle size and size distribution, zeta potential, solubility, drug release, antioxidant activity, and in vitro antitumor activity. It was observed that both hydroxypropyl methylcellulose-stabilized nanosuspension and sodium dodecyl sulfate-stabilized nanosuspension produced an enhancement in physical stability, antioxidant potential, and in vitro cytotoxicity compared with naringenin. Furthermore, hydroxypropyl methylcellulose-stabilized nanosuspension was found to be better than sodium dodecyl sulfate-stabilized nanosuspension in terms of particle size and size distribution, storage stability, and drug release. This study showed that nanosuspension formulations could be a potential strategy for improving dissolution and antitumor activity of naringenin.
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  • 6
    Publication Date: 2020-07-13
    Description: This paper introduces the synthesis of mesoporous silica nanoparticles (MSNs) with three different groups such as amine, thiol, and sulfonic acid, along the internal surface. Trimethyl[3-(trimethoxysilyl)propyl]ammonium chloride was used to modify the external surface of the nanomaterials. Such materials allow control of the drug release from MSN pores. Multifunctional MSNs were loaded with doxycycline (Doxy) to study their capacities and uploading time. The loading profile indicates that sulfonic groups in the internal surface were the most efficient surfaces with a loading capacity of ca. 35% in 90 min in acidic media.
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  • 7
    Publication Date: 2020-07-15
    Description: To effectively prevent the accumulation of copper tailings from producing acid mine drainage (AMD) and maximize the comprehensive utilization of copper tailings, the process of oxidation roasting was adopted to release sulfur in the form of SO2 to achieve the purpose of sulfur recovery later. Based on the AMD risk assessment, thermogravimetric (TG) analysis, and differential scanning calorimeter (DSC) analysis, the influences of roasting temperature, residence time, and air flow in the roasting process were investigated. The thermal stability, reaction equilibrium, mineral transformation, and residual S content were characterized by TG-DSC, HSC chemical software 6.0, X-ray diffraction (XRD), and combustion neutralization, respectively. The optimum conditions for sulfur release in the roasting process were shown with a temperature of 1200°C, a residence time of 60 min, and an air flow of 0.8 L/min. Under these conditions, the sulfur release rate was 99.82%, and the residual S content was 0.05%. Subsequently, the process of sulfur release was proposed as four steps: oxidative decomposition of pyrrhotite, formation of ferric sulfate, decomposition of ferric sulfate, and formation of hematite. All of the findings could propose a theoretical and experimental reference for the recovery of the sulfur component from tailings rich in sulfide minerals.
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  • 8
    Publication Date: 2020-07-08
    Description: This study aimed to determine the effects of diets replacing soybean meal with safflower meal and phytase enzyme on feed utilization, growth performance, body composition, serum biological parameters, and environmental effects of rainbow trout (Oncorhynchus mykiss). To this aim, five different isonitrogenous (44%) and isocaloric (23 kJ) experimental feeds were formulated as follows: the control group (C) containing no safflower meal and enzyme; SFM10 and SFM20 groups containing 10% and 20% of safflower meal instead of soybean meal, respectively; and SFM10 ± P1000 and SFM20 ± P2000 groups containing 10% safflower meal and 1000 IU/kg phytase and 20% safflower meal and 2000 IU/kg phytase, respectively. Juveniles (12.57 ± 3.05 g average weight) were fed for 60 days. As a result, the best growth rate and feed conversion were recorded in the SFM20 ± P2000 group with 127.07 ± 7.73% and 1.13 ± 0.020, respectively p
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  • 9
    Publication Date: 2020-07-09
    Description: C and N codoped TiO2 nanoparticles were synthesized via a solvothermal method. The degradation of Rhodamine B by the photocatalyst C, N-TiO2 was investigated under visible-light irradiation generated by using a 36 W compact fluorescent lamp which is characterized by wavelengths from 400 to 650 nm. The structure and properties of the obtained photocatalyst have been systematically investigated using X-ray diffraction, TEM, UV-Vis, FT-IR, and BET techniques. The experimental results revealed that C, N codoped TiO2 nanoparticles were successfully synthesized, with an average diameter of 9.1 nm. C, N-TiO2 nanoparticles exhibited an energy band gap of 2.90 eV, which were lower than pristine TiO2 (3.34 eV), C-TiO2 (3.2 eV), and N-TiO2 (3.03 eV). The degradation of Rhodamine B by C, N-TiO2 indicated that, under visible-light irradiation, the optimal dose of the photocatalyst was 1.8 g/L, and the removal of Rhodamine B was almost complete after 3 hours of reaction. The photocatalytic degradation of Rhodamine B in the range of 5–100 mg/L showed that the process followed the first-order kinetics according to the Langmuir–Hinshelwood model. The highest apparent rate constant (0.0427 min−1) was obtained when the initial concentration of Rhodamine B was 5 mg/L, whereas the former decreased with the increase in the initial concentration of Rhodamine B. Moreover, C and N codoped TiO2 nanoparticles presented a high potential for recycling, which was characterized by a removal efficiency of more than 86% after three cycles.
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  • 10
    Publication Date: 2020-07-09
    Description: In order to reduce the nitrogen oxide emission of cement plant, the denitrification of decomposing furnace is studied in this paper. Based on Fluent software platform, the 2500 t/d new dry-process cement kiln decomposing furnace of a plant is modeled and simulated by using air fractional combustion technology combined with selective noncatalytic reduction technology. The model and simulation methods are verified by the field test. The effects of the urea injection position and ammonia-nitrogen molar ratio on NO, NH3, and denitrification efficiency are studied by numerical simulation. The results show that the optimal injection position of the urea solution is 12 m, the optimal ammonia/nitrogen molar ratio is 1.8, and the optimal injection velocity of the urea solution is 40 m/s. The simulation results obtained under the optimal parameters are as follows: NO concentration is 187.60 mg/m3, NH3 escape is 32.40 mg/m3, and denitrification efficiency is 74.75%.
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  • 11
    Publication Date: 2020-07-11
    Description: Magnetically separable strontium hexaferrite SrFe12O19 was prepared using the chemical coprecipitation method, and the nanostructured material was characterized by X-ray diffraction, scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), and BET analysis. The SEM images showed the homogeneity of the chemical composition of SrFe12O19 and uniform distribution of size and morphology. The pore size of the nanomaterial and its specific area were determined by BET measurements. Strontium hexaferrite SrFe12O19 exhibited a strong magnetic field, which is highly suitable in the heterogeneous catalysis as it can be efficiently separated from the reaction. The magnetic nanocatalyst showed high activity and environmentally benign heterogeneous catalysts for the epoxide ring-opening with amines affording β-amino alcohols under solvent-free conditions. When unsymmetrical epoxides were treated in the presence of aromatics amines, the regioselectivity was influenced by the electronic and steric factors. Total regioselectivity was observed for the reactions performed with aliphatic amines. The magnetically SrFe12O19 nanocatalyst showed excellent recyclability with continuously good catalytic activities after four cycles.
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  • 12
    Publication Date: 2020-07-07
    Description: Three different plants (Solanum indicum, Solanum surattense, and Solanum nigrum) of Solanaceae family were explored to extract and characterize hydrocolloids in aqueous solution. S. indicum fruit fractions bring in maximum hydrocolloid yield of 21.39 ± 0.42% based on % dry weight of the sample. The observed order of extracting hydrocolloid yield amongst investigating aerial parts of S. surattense, S. nigrum, and S. indicum (% dry weight) is fruits 〉 stem 〉 leaves. Maximum protein (22%) and starch (0.85%) contents were observed in fruit fractions of S. nigrum and S. indicum, respectively. Among the functional characteristics, the fruit fraction of S. indicum has higher water-holding capacity (24.80%), oil-holding capacity (2.96%), emulsifying activity (90%), emulsion stability (70%), foaming capacity (65%), and foaming stability (90%). Monosaccharide profiling results showed the presence of glucose, galacturonic acid, galactose, glucuronic acid, arabinose, and xylose in extracted fractions. The findings propose that hydrocolloids (extracted with water) are cost-effective and would be potential candidate as a substitute for pectin added into foamy and frothy food products and frothy beverages.
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  • 13
    Publication Date: 2020-08-24
    Description: Cubic boron nitride (cBN) single crystals are synthesized under high temperature and high pressure in the Li-based system. The growth defects on hexagonal and triangular (111) surfaces of cBN single crystals after rapid cooling are discussed systemically for the first time using the atomic force microscope. Some impurity particles, triangle cone hole defects, lamellar-fault structures, and big steps are obvious on the surfaces of cBN single crystals. The formation mechanism of these defects is analyzed briefly at the synthetic process of cBN single crystals, and the growth mechanism of cBN single crystals transform from the two-dimensional growth to dislocation growth mechanism under high temperature and high pressure.
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  • 14
    Publication Date: 2020-04-23
    Description: In this study, we are presenting the effect of three ripening stages of air-dried bitter gourd fruit extracts on phenolic acid composition, antioxidant, antibacterial, and anticancer activities. The results showed mature bitter gourd fruit extract in 100% methanol showing 78% DPPHº scavenging activity. Immature dried fruit extract in 80% and 100% methanol showed promising antibacterial activities, i.e., 〉18.5 ± 0.21 mm zone-of-inhibition against Staphylococcus aureus, while mature dried fruit extract in 80% methanol showed 18.4 ± 0.17 mm zone-of-inhibition against Escherichia coli. Anticancer activity results of 100% methanol extracts of ripened fruit possess showed 6.72 ± 1.81 and 3.55 ± 0.51 mg/mL IC50 values with HeLa and MDBK cancer cell lines, respectively. The overall results indicate that the immature and ripen fruits of BG could be extracted in pure methanol as an antibacterial and anticancer phytomedicine.
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  • 15
    Publication Date: 2020
    Description: Residual levels of 11 organochlorine pesticides (OCPs) in surface water of Jiuxi Valley were determined during spring and autumn at nine sampling points to assess their contamination and potential risks. The water samples were extracted by solid-phase extraction (SPE), and OCPs were analyzed by gas chromatograph equipped with a 63Ni-ECD detector. The investigation results indicated that the concentration of total OCPs varied from 4.07 to 13.5 ng·L−1 with an average value of 7.15 ng·L−1 in spring, and from 12.5 to 30.1 ng·L−1 with an average value of 19.9 ng·L−1 in autumn. Jiuxi Valley was slightly contaminated by OCPs, and the concentrations of ΣHCHs and ΣDDTs in the river were at relatively low levels. HCHs were the main pollutant in spring, and also in autumn, and α-HCH was the main component of the HCH isomers at most sampling points. Source analysis indicated that local use of lindane or input of fresh γ-HCH contributed to the presence of HCHs. New inputs were the major sources of DDTs, aldrin, heptachlor, and endrin. The OCP levels of this investigation were within the standard limits set by a majority of the water quality standards and guidelines of China, WHO, European Union, and Canada. However, although the γ-HCH concentrations at all sampling sites, endrin concentrations at all sampling sites, and β-HCH concentrations at most sampling sites were below the human health water quality standard, and the levels of other tested OCPs (α-HCH, p,p′-DDD, p,p′-DDE, p,p′-DDT, aldrin, and heptachlor) exceeded the value of EPA-recommended water quality criteria for human health, which indicated potential risks to human health around the region.
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  • 16
    Publication Date: 2020
    Description: The shortage of water resources in Saudi Arabia is becoming an increasingly serious problem. Management of sewage water is an attractive option to reduce the contamination of water resources such as ground water. This work aims to use bauxite rock as a low-cost adsorbent/coagulant for sewage water treatment in a simple and rapid technique. Different doses (1, 2, 3, 4 and 5 g/l) of the grinded bauxite was used as an adsorbent/coagulant. The results revealed that, at rock doses of 1, 2, 3, 4, and 5 g/l, the COD concentration was decreased from 326 to 134, 98, 83, 70, and 65 mg/l, respectively, while the BOD concentration was lowered from 243 to 196, 104, 71, 60, 51, and 47 for the same rock doses. This was reflected on the turbidity of the treated effluent from each treatment step. Also, the FC counts were reduced to 2 log units. Furthermore, the dose of 3 g/l of the grinded bauxite rock was found to be the least economic dose for the treatment of sewage water. Bauxite mineral has been used explicitly in a high-performance, very affordable method for wastewater treatment.
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  • 17
    Publication Date: 2020
    Description: A proper understanding of the properties of iron could increase the effectiveness of programmes for alleviating iron deficiency. Recently, encapsulation has been considered an appropriate method for protecting iron from injurious reactions. However, several events may occur during encapsulation processes, including changes in the iron’s oxidation state. Oxidation of ferrous iron is not desirable since the intestines can only absorb iron in the ferrous form. In this study, a cyclic voltammetry method was applied to investigate the likelihood of ferrous gluconate oxidation for the preparation of chitosan-tripolyphosphate microparticles. Then, the electrochemical properties of ferrous gluconate were confirmed experimentally. The oxidation rate of ferrous gluconate is also discussed in this paper. All the experimental solutions were formulated in detail to produce conditions similar to those of microparticle production. Cyclic voltammetry analysis was conducted using a configuration of three electrodes connected to an electrochemical analyser. Graphite, platinum wire, and Ag/AgCl were employed as the auxiliary, working, and reference electrodes, respectively. The cyclic voltammetry results show that the observed potential for each anodic peak shifted negatively in the presence of chitosan and sodium tripolyphosphate. Moreover, the rate of ferrous oxidation tended to increase during 75 min of experiments due to the presence of chitosan and sodium tripolyphosphate. These behaviours indicate the transformation of ferrous iron to ferric iron during iron microparticle preparation. Furthermore, these findings suggest that spray drying is a preferable method to minimise the oxidation reaction.
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  • 18
    Publication Date: 2020
    Description: Enzyme-assisted extraction (EAE) and ultrasound-assisted extraction (UAE) were popular methods used to extract bioactive compounds from citrus peels, by-products of fruit processing industry. In this study, the total phenolic content (TPC), total flavonoid content (TFC), naringin and hesperidin contents, and antioxidant and antimicrobial activities of the extracts from pomelo peels using the combined enzyme and ultrasound-assisted extraction (E-UAE) or ultrasound and enzyme-assisted extraction (U-EAE) technique were investigated and compared with those extracted using the EAE and UAE. The optimal EAE conditions were as follows: enzyme concentration of 2%, water-solid ratio of 40 ml/g, incubation temperature of 50°C, and extraction time of 60 min, whereas the optimal UAE conditions were ultrasonic energy of 40 kHz, water-solid ratio of 40 ml/g at room temperature, and extraction time of 60 min. The results indicate that the total phenolics, total flavonoids, naringin, and hesperidin contents of the extracts significantly increased in the following order of the extraction techniques: UAE 
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  • 19
    Publication Date: 2020
    Description: Mononuclear chelates of Ni(II), Co(II), Fe(III), Cd(II), and Cu(II) derived from triazole novel tridentate ligands were prepared and characterized by different spectroscopic methods. The metal to ligand ratio was 1 : 2, which was revealed by elemental analysis. All the complexes were electrolytic in nature as suggested by the conductivity measurements. IR pointed out that the coordination of the triazole ligand toward the metal ions was carried out through N amino and S thiophenolic atoms. The complexes were found to have octahedral geometry, and their thermal stability was also studied. The XRD spectrum of Co(II) and Fe(III) complexes concluded their crystalline structure. The parent ligand and its chelates were investigated for antimicrobial potential. Bioassay of all triazole complexes showed increased activity as compared to that of the ligand. The complexes having Ni(II), Co(II), and Cu(II) ions as metal center exhibited superior antibacterial activity in opposition to Gram-positive (B. subtilis and S. pyogenes) and Gram-negative (E. coli and P. vulgaris) bacterium as compared to standard.
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  • 20
    Publication Date: 2020
    Description: Ion sensor properties of 4-(1-(4-hydroxy-3-methoxybenzyl)-1H-benzo[d]imidazol-2-yl)-2-methoxyphenol (L) in acetonitrile-water (1 : 1) were evaluated by fluorescence spectrometry. Pronounced quenching in the fluorescence spectra of the ligand was only observed for the Cu2+ ion among many metal ions. Linear fluorescence responses of the ligand at 360 nm as the function of the Cu2+ concentration were used for the determination of the Cu2+ ion in spiked tap water samples. Recovery values (R%) were satisfactory, and relative standard deviation (RSD%) was below 5.00 in intraday and interday measurements. Detection and quantification limits were 0.28 and 0.84 μg/L, respectively. The assay based on external calibration only took a few minutes.
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  • 21
    Publication Date: 2020
    Description: Due to the ever-growing demand for high-density energy storage devices, lithium-ion batteries with a high-capacity cathode and anode are thought to be the next-generation batteries for their high energy density. Lithium sulfide (Li2S) is considered the promising cathode material for its high theoretical capacity, high melting point, affordable volume expansion, and lithium composition. This review summarizes the activation and lithium storage mechanism of Li2S cathodes. The design strategies in improving the electrochemical performance are highlighted. The application of the Li2S cathode in full cells of lithium-ion batteries is discussed. The challenges and new directions in commercial applications of Li2S cathodes are also pointed out.
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  • 22
    Publication Date: 2020
    Description: Diazepam is a benzodiazepine that has the potency to be misused because it is effective, easily obtained, and inexpensive. The misuse of diazepam is to replace illegal drugs and be a sedative. Separation of diazepam is needed to detect possible drug abuse and to monitor drug levels in blood to ensure the effectiveness of the drug. This study was conducted to obtain a molecularly imprinted solid-phase extraction (MI-SPE) sorbent to separate diazepam from serum samples. This work started at the synthesis stage with the bulk polymerization method, using methyl methacrylate and acrylamide as functional monomers, diazepam as a template, and ethylene glycol dimethacrylate as a crosslinker. The polymer obtained was identified by its adsorption capacity and packaged into a solid-phase extraction (SPE) cartridge, and the extraction conditions were optimized. The optimization results were then used to extract diazepam from the serum sample. The test results showed that the adsorption ability of the molecularly imprinted polymer (MIP) with the functional monomer, methyl methacrylate, was 63.98 ± 0.1%, which is higher than that of the acrylamide MIP monomer, with a value of 43.27 ± 0.1%. The MIP sorbent of methyl methacrylate was applied to the SPE with 200 mg of polymer in a 3 mL cartridge. Diazepam added to serum samples were then passed through the MIP-SPE producing a percent recovery value of 95.31 ± 1.1% for MIP and 60.83 ± 0.3% for nonimprinted polymer (NIP). The results showed that the MI-SPE sorbent made from the monomer methyl methacrylate gave higher extraction recovery results than acrylamide, and it could be used for extracting diazepam from serum samples with or without other substances.
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  • 23
    Publication Date: 2020
    Description: In this study, antimicrobial spectrum of erythorbyl laurate (EL) against bacteria and fungi, leading to food-borne and infectious skin diseases, was evaluated for its practical applications in food and cosmetics. Furthermore, the influences of environmental factors including pH, oxidative stress, and dispersion medium on antimicrobial activity of EL were investigated. The three Gram-positive bacteria and the three molds were susceptible to 3.0 mM EL, while the yeast was susceptible to 6.0 mM EL. It was demonstrated EL retained antibacterial activity against Staphylococcus aureus after being oxidized while the antibacterial activity against the three Gram-positive bacteria including S. aureus, Bacillus cereus, and Listeria monocytogenes was significantly enhanced as decrease of pH from 7.0 to 5.0. Moreover, EL exhibited bactericidal effects against both Gram-positive and Gram-negative bacteria in an oil-in-water emulsion. Treatment of 5.0 mM EL for 4 h reduced 5.29 ± 0.24, 6.01 ± 0.18, 5.95 ± 0.13, and 6.24 ± 0.30 log CFU/mL against S. aureus, L. monocytogenes, Pseudomonas aeruginosa, and Escherichia coli, respectively. In a multipassage resistance selection study, it was observed minimum inhibitory concentrations of EL against S. aureus were not increased over 20 passages, indicating EL might not develop drug resistance of bacteria. This study suggests EL has a potential to be applied as the multifunctional additive in food and cosmetics.
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  • 24
    Publication Date: 2020
    Description: Eutrophication of surface water has become an environmental concern in recent decades. High concentrations of nutrients, especially nitrogen- and phosphorus-rich species, have contributed to the process of eutrophication, highlighting a demand for effective and economical methods of removing nitrogen and phosphorus from wastewater. This study aimed to investigate the ability of a green microalga species, Scenedesmus sp., to remove nitrogen and phosphorus, as well as chemical oxygen demand (COD) and biochemical oxygen demand (BOD5), from fertilizer plant wastewater. Different microalgae concentrations from 10 mg/L to 60 mg/L were used to assess the growth rate, biomass production, and removal ability. The results indicated that Scenedesmus sp. grew well in the wastewater (with a growth rate from 0.3 to 0.38/day) and produced up to 70.2 mg/L of dry biomass. The algal species was able to remove ammonium (), nitrate (), phosphate (), total phosphorus (TP), COD, and BOD5 with removal rates up to 93%, 84%, 97%, 96%, 93%, and 84%, respectively. Autobioflocculation (AFL) was observed in all cultures with flocculation activity of up to 88.3% in the highest algal biomass treatment. The formation of bioflocculation enhanced the removal of nutrients, COD, and BOD5 from wastewater effluent. The results indicated that wastewater from a fertilizer plant could be used as a cost-effective growth medium for algal biomass. The autoflocculation of microalgae could be used as a more practical approach for wastewater treatment using microalgae to eliminate eutrophication.
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  • 25
    Publication Date: 2020
    Description: The Raphanus sativus L. ethanol extract was prepared by radish cake maceration in ethanol end tested as a scale and corrosion inhibitor of mild steel in tap water. Antiscalant efficiency was tested with electrochemical and thermal scaling techniques, and changes in hardness content were determined titrimetrically. No deposits were found on the metal surface at the extract concentration of 10 mL/L in chronoamperometry test, and scaling suppression was established 5 times in thermal scaling conditions. The linear polarization resistance technique was used to determine corrosion rate. Inhibition efficiency was found to be 75% in thermal scaling conditions. The formation of the surface film was responsible for both scaling and corrosion suppression on mild steel surface as was established with FT-IR spectroscopy and SEM. The surface film was found to contain polymerization products of isothiocyanates.
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  • 26
    Publication Date: 2020
    Description: The mechanism of the formation of the hydrophobic agglomerate in fine scheelite flotation was studied using zeta potential measurement, contact angle measurement, optical microscope measurement, and atomic force microscopy (AFM) colloid probe technology. Zeta potential measurement results confirmed the adsorption of sodium oleate on scheelite, fluorite, and calcite surface and surface potential difference at different pH values of ultrapure water. Contact angle measurement results confirmed the surface of nature scheelite, fluorite, and calcite was hydrophilic, and the surface after thread by sodium oleate solution was hydrophobic. The optical microscope measurement results confirmed the agglomerates could really form in ultrapure water of pH 8 or 10 and in 1 mM sodium oleate solution of pH 10. The agglomerations were empty and not tight in ultrapure water. On the contrary, the hydrophobic agglomerations were larger and denser after treated with sodium oleate solution than that of in ultrapure water. According to the AFM experiment results, the interaction forces on hydrophilic scheelite-scheelite and scheelite-fluorite were repulsive at pH 5.6 and attractive at pH 8 or 10. However, the interaction forces on hydrophilic scheelite-calcite were attractive at pH 5.6, 8 or 10. The interaction forces on hydrophobic scheelite-scheelite, scheelite-fluorite, and scheelite-calcite were attractive strongly due to the existence of hydrophobic force. The measurement results of the interaction forces were in good agreement with the changes of zeta potential and contact angle at different conditions. The combined results could be beneficial to understand the interaction force in fine scheelite flotation.
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  • 27
    Publication Date: 2020
    Description: The reformulated Zagreb indices of a graph are obtained from the original Zagreb indices by replacing vertex degrees with edge degrees, where the degree of an edge is taken as the sum of degrees of its two end vertices minus 2. In this paper, we obtain two upper bounds of the first reformulated Zagreb index among all graphs with p pendant vertices and all graphs having key vertices for which they will become trees after deleting their one key vertex. Moreover, the corresponding extremal graphs which attained these bounds are characterized.
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  • 28
    Publication Date: 2020
    Description: Sorghum bicolor (S.B.) is used in this work for preparing chemically modified adsorbent for toxic metal ions, i.e., cadmium(II) and copper(II). Thiourea is selected for chemical modification of this plant waste by microwave solid fusion methodology, so that its chelating ability for metal ions can be enhanced in both acidic and basic conditions, in a cheaper and quicker way. Characterization was carried out by different physiochemical means using FT-IR, SEM, etc. An increase in pHpzc value was observed in TSB, which is confirmed by FT-IR analysis. The effect of biosorption process parameters was also studied and found that maximum removal of these toxic ions occurred in slightly acidic pH (5-6) conditions, following pseudo-second-order kinetic model. Boyd plots indicated that film dispersion mode was the rate-determining step. Langmuir model indicated that the maximum metal ion removal capacity of TSB was 17.241 mg/g and 15.151 mg/g for cadmium(II) and copper(II) ions. So, TSB can be used on a larger scale for toxic metal ion removal by Sorghum bicolor waste in a cleaner way.
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  • 29
    Publication Date: 2020
    Description: The fruit Malus prunifolia (Malus micromalus Mak.), which belongs to the Rosaceae family, grows mostly in the upper-middle reaches of the Yellow River area. It has long been popular as a fruit commodity and as a natural remedy. Its main biologically active components include vitamin C, phenolics, flavonoids, polysaccharides, and triterpenic acids. Recent phytochemical studies on the fruit have shed some light on its biological activities, such as anticancer, immunomodulatory, antioxidant, immunostimulating, hepatoprotective, and gastrointestinal protective activities. A stronger focus on clinical studies and phytochemical characterization of the fruit will be essential for future research efforts. This minireview could be useful for predicting its other medicinal uses and its potential drug or food interactions, and it could be beneficial for people living in areas where the fruit is endemic and where healthcare resources are scarce.
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  • 30
    Publication Date: 2020
    Description: This study reports the anti-inflammatory activity-guided fractionation of the aerial part of Piper bavinum C. CD. (Piperaceae) that led to the isolation of eight secondary metabolites (1–8). The chemical structures of 1–8 were established mainly by NMR and mass spectra. Compound 5 was isolated from P. bavinum for the first time. All the isolated compounds were evaluated against LPS-induced NO production in macrophage RAW 264.7 cells in vitro. Among them, compound 4 showed the most potent inhibitory activity against the LPS-induced NO production with an IC50 value of 5.2 μM followed by compound 5 that inhibited NO production with an IC50 value of 13.5 μM. In the protein levels, compound 4 suppressed LPS-induced COX-2 and iNOS expressions in a dose-dependent manner. The results suggested that P. bavinum and its constituents might exert anti-inflammatory effects.
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  • 31
    Publication Date: 2020
    Description: Data envelopment analysis (DEA) as a nonparametric programming approach has been widely extended and applied in many areas. Conventional DEA models can well measure the efficiency of inefficient decision-making units (DMUs) but cannot further discriminate the efficient DMUs. A lot of methods are proposed to address this problem. One of the most important methods is the slacks-based measure of super-efficiency model (S-SBM model) developed by Tone in 2002. However, the projection for a DMU on the efficient frontier identified by S-SBM model may not be strongly Pareto-efficient that makes the super-efficiency score misestimated. This paper revises the usual slacks-based measure of super-efficiency by incorporating input saving and output surplus scaling factors into the objection function for measuring DMUs. We integrate SBM model and S-SBM model effectively and yield input saving and output surplus scaling factors as well as input and output slacks under only one integrated model. According to the study, the projection reference point identified by our method is strongly Pareto-efficient. Meanwhile, how each decision variable influences the efficiency score for a specific DMU is revealed and illustrated through two numerical examples and an empirical study in paper chemical mills.
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  • 32
    Publication Date: 2020
    Description: In mineral flotation, rheological problems have limited the efficient upgrading of low-grade and complex ores. Since pulp and froth rheology are deemed to play different roles in influencing the separation performance, in this paper, a brief review on pulp and froth rheology in flotation is provided, with an objective of developing a basic understanding of rheology in flotation. The essential variables that affect the rheology of a flotation pulp and froth are discussed. The methods for measuring pulp and froth rheology are presented. The correlations of pulp and froth rheological properties to flotation performance are reviewed. Strategies that are currently used to mitigate the deleterious effects of problematic ores in flotation are also provided for flotation optimization. Research gaps are also proposed to highlight the need of further exploration of flotation rheology in future.
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  • 33
    Publication Date: 2020
    Description: Coastal waters are polluted by heavy metals to varying degrees, posing potential risks to marine ecology and human health. In May 2006, the pollution levels, sources, and ecological risks of heavy metals (Cu, Pb, Zn, Cd, Hg, and As) in seawater, surface sediments, and living organisms were studied in Jiuzhen Bay in Fujian, China. This study identified Hg (0.26–0.72 µg/L) and As (20.3–31.5 µg/L) pollution in the seawater of Jiuzhen Bay. In sediments, heavy Pb pollution (946 µg/g dw) was only detected at one station at a level posing very serious potential risk, while Hg pollution (0.052–0.087 µg/g dw) was observed at three stations at a level posing serious potential risk. No heavy metal pollution was detected in sediments at other stations. The concentrations of five heavy metals (Cu, Zn, As, Cd, and Pb) exceeded the corresponding National Quality Standards for oysters, indicating heavy pollution, based on an ecological risk assessment. In clams, two heavy metals (Pb and As) exceeded the standards, indicating light pollution, based on an ecological risk assessment. No heavy metal pollution was found in fish or shrimps. The heavy metals in the seawater and sediments of Jiuzhen Bay are mainly derived from the river discharges of Luxi and Wujiang Rivers although sewage discharge along the coast of Jiuzhen Bay is another source of heavy metal pollution at some stations. Given the pollution of Pb, Hg, and As in seawater and sediments at some stations within the bay, the potential risks of Pb, Hg, and As in living organisms to both the marine ecology and human health deserve increased attention.
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  • 34
    Publication Date: 2020
    Description: The sonication-mediated oxidative-radical copolymerization using ammonium persulfate in acidic medium provides a new successful avenue to graft Chitosan with three methylaniline derivatives. The synthesized Chitosan-graft-polymethylanilines (CGPMA) were characterized using FTIR, UV-vis diffuse reflectance spectroscopy, XRD, thermogravimetric analysis (TGA), elemental analysis, and transmission electron microscopy (TEM). XRD spectra revealed that CGPMA have a higher crystallinity degree compared to the pristine Chitosan. In addition, a methyl position-dependent crystallinity is noticeable for the grafted copolymers. This could be confirmed from TEM images that reflect structure-affected morphologies of different ordering for the graft spherical nanoparticles. Interestingly, the copolymers prepared under ultrasonic irradiation show a high potency in dye uptake compared to nonsonicated ones. Moreover, an antibacterial preliminary test on the as-prepared materials was accomplished. We have achieved promising results, which encourages us to conduct more studies to process these materials in developing biomedical active composites.
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  • 35
    Publication Date: 2020-04-22
    Description: The Tunisian coast is suffering from several active or abandoned polluted sites, suspected to have released high concentrations of various contaminants infiltrating the environment and probably causing groundwater degradation. Within this scope, this study comes to assess and model the Sfax-Agareb aquifer contamination by fluoride released through phosphogypsum leachate percolation. For that, a spatial-temporal monitoring of fluoride contents was achieved for the period between October 2013 and October 2014. Observed data show that hazardous water contamination is occurring especially close to the phosphogypsum leachate collection basins. At this level, groundwater fluoride concentrations may reach up to 29 mg/L. Flow and transport modeling to evaluate fluoride contamination plume expansion in 2030 was achieved using MODFLOW and MT3DMS software packages based on a homogeneous and isotropic aquifer conceptual model. Flow and transport model calibrations were assessed by varying hydraulic conductivity, effective porosity, and dispersivity and then validated through observed data for two reference dates (October 2013 and October 2014). Based on the Tunisian NT 106-002 liquid discharge norms, fluoride contamination front was set at 3 mg/L. Numerical simulation shows that, in 2014, plume contamination by fluoride in the saturated zone extended over 250 m from the contamination source. In 2030, the spatial extent of this contamination will extend over a distance of 900 m towards the sea, following the aquifer flow direction. At the control piezometer, fluoride concentrations will increase from 29 mg/L in 2014 to 86 mg/L in 2030. This study, using numerical modeling, gives new insights for short- and medium-term prediction of eventual fluoride concentrations in the saturated zone of the Sfax-Agareb aquifer.
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  • 36
    Publication Date: 2020
    Description: Densities of sodium arsenite (NaAsO2) aqueous solution with the molality varied from 0.19570 to 1.94236 mol·kg−1 at temperature intervals of 5 K from 283.15 to 363.15 K and 101 ± 5 kPa were measured by a precise Anton Paar Digital vibrating-tube densimeter. Apparent molar volumes (VΦ) and thermal expansion coefficient (α) were obtained on the basis of experimental data. The 3D diagram of apparent molar volume against temperature and molality and the diagram of thermal expansion coefficient against molality were generated. According to the Pitzer ion-interaction equation of the apparent molar volume model, the Pitzer single-salt parameters (,,, and , MX = NaAsO2) and their temperature-dependent correlation F(i, p, T) = a1 + a2ln (T/298.15) + a3(T − 298.15) + a4/(620 − T) + a5/(T − 227) (where T is temperature in Kelvin and ai are the correlation coefficients) for NaAsO2 were obtained for the first time. The predictive apparent molar volumes agree well with the experimental values, and those results indicated that the single-salt parameters and the temperature-dependent formula are reliable.
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  • 37
    Publication Date: 2020
    Description: To elucidate the chemical compositions of Prunus cerasifera Ldb leaves, the methanol extracts were firstly fractionated by ethyl acetate and n-butanol, respectively. The phenolic acid-rich fractions (ethyl acetate extracts) were further isolated by various chromatographic columns (CC) including MCI macroporous resin, normal-phase silica gel, Sephadex gel LH-20, octadecyl silane (ODS), and preparative HPLC to yield the phenolic compounds. The isolated compounds were analyzed by 1H-nuclear magnetic resonance (1H-NMR), 13C-NMR, and electrospray ionization mass spectral (ESI-MS) spectroscopy. Eleven phenolic acids were identified as p-coumaric acid (1), caffeic acid (2), ferulic acid (3), chlorogenic acid (4), 3-O-caffeoylquinic acid (5), 5-O-coumaroylquinic acid (6), 3-O-caffeoylquinic acid methyl ester (7), chlorogenic acid methyl ester (8), 3-O-caffeoyl-5-O-coumaroylquinic acid or 3-O-coumaroyl-5-O-caffeoylquinic acid (9), gallic acid (10), and protocatechuic acid (11). The current study pioneers to identify and report all the phenolic constituents from P. cerasifera Ldb leaves.
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  • 38
    Publication Date: 2020
    Description: Tetrapleura tetraptera is widely cherished in African traditional homes because of its alleged therapeutic and nutritional properties. This present study aimed at determining the levels of vitamin A, C, E, and beta-carotene and trace element (Fe, Cu, Mn, Co, Se, and Zn) concentrations and their extractabilities in the pulp, seeds, and whole fruit (mixture of pulp and seeds) of T. tetraptera. The total trace element concentration of Fe, Cu, Co, Mn, and Zn and their extractabilities (%) were determined using flame atomic absorption spectrometer (FAAS), whereas UV-VIS spectrophotometer was used to determine selenium concentration. The trace element content (mg/kg) based on dry weight in the pulp, seeds, and whole fruit was Fe (162.00 ± 7.14, 115.00 ± 12.00, and 154.00 ± 25.20, respectively), Zn (31.60 ± 4.77, 43.40 ± 5.29, and 41.50 ± 8.97, respectively), Cu (16.10 ± 4.98, 11.90 ± 8.40, and 17.20 ± 14.50, respectively), Mn (55.30 ± 2.41, 156.00 ± 10.20, and 122.00 ± 5.29, respectively), Co (38.10 ± 6.40, 21.10 ± 7.15, and 44.00 ± 14.90, respectively), and Se (1.49 ± 0.17, 2.43 ± 0.28, and 2.97 ± 0.27 μg/g, respectively). The mineral extractabilities (%) in the pulp, seeds, and whole fruit of T. tetraptera were established to be in the order Co 〉 Zn 〉 Fe 〉 Cu 〉 Se 〉 Mn. Also, the chromatographic method (HPLC) was used to evaluate vitamin E concentration, and vitamin C and concentration of beta-carotene were calculated from the obtained concentration of vitamin A using a conversion factor by the titrimetric method. From the results of vitamin analysis, a significant difference () was observed among the pulp, seeds, and whole fruit for vitamin C and E. However, no significant difference () was perceived among these plant parts for vitamin A and beta-carotene. This study has therefore revealed that the pulp, seeds, and whole fruit of T. tetraptera contain varying concentrations of vitamins and trace elements and has given many vital insights on which part of T. tetraptera to consume, as concentrations of these nutrients differ in the discrete parts of the fruit.
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  • 39
    Publication Date: 2020
    Description: The recombinant thyroid hormone receptor (TR) gene yeast assay was used to evaluate thyroid disruption caused by groundwater from the riverbank filtration (RBF) system in Wuchang City, China. To investigate seasonal fluctuations, groundwater was collected during three seasons. Although no TR agonistic activity was found, many water samples exhibited TR antagonistic activity. The bioassay-derived amiodarone hydrochloride (AH) equivalents ranged from 2.99 to 274.40 μg/L. Water samples collected from the riverbank filtration system during the dry season had higher TR antagonistic activity. All samples presented adverse 3,3′,5-triiodo-L-thyronine (T3) equivalent levels, ranging from −2.00 to −2.12 μg/kg. Following exposure to water samples with substantial TR antagonist activity, predicted hormonal changes in humans of different gender and age ranged from 0.65 to 1.48 μg/kg of T3, being 47% to 231% of normal. No obvious difference was found between genders or among age groups. Overall, the results revealed that the RBF system could remove the thyroid-disrupting chemicals in the river water to some extent. Considering the varying degrees of risk to human health, further treatment is needed to remove the potential thyroid-disrupting chemicals in pumping water after riverbank filtration to ensure drinking water safety.
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  • 40
    Publication Date: 2020
    Description: In this paper, we give a geometric interpretation of the Laplacian matrix of a connected nonsingular mixed graph which generalizes the results of M. Fiedler (M. Fiedler, Geometry of the Laplacian, Linear Algebra Appl., 2005, 403: 409–413). In addition, the relations of geometric properties between a connected (singular or nonsingular) mixed graph, and all its resigned graphs will be characterized.
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  • 41
    Publication Date: 2020
    Description: In this work, the mechanism and regio- and no-periselectivity of the 1,3-dipolar cycloaddition reaction of 2,4-dimethyl-3H-1,5-benzodiazepine with N-aryl-C-ethoxycarbonylnitrilimine have been studied using the DFT method at the B3LYP/6-31G(d) level of theory. IRC calculations and activation energies show that this reaction follows an asynchronous concerted mechanism. The two C=N sites of 2,4-dimethyl-3H-1,5-benzodiazepine are easily reached by the dipole, and the energy barrier between the reagents and the transition states is too weak. The secondary barriers are traversed by the heat released in the reaction medium after the crossing of the first TS, which facilitates the addition reaction and does not require high energy. The obtained results of this study are in good agreement with experimental outcomes.
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  • 42
    Publication Date: 2020
    Description: Cationic and zwitterionic polyelectrolytes are synthesized through atom transfer radical polymerization (ATRP), comprising a polyfluorene backbone with a small fraction of 2,1,3-benzothiadiazole and poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) side chains. Due to higher charge density generated from grafted side chains, two polymers show higher water solubility and higher quantum yield. In comparison with cationic polyelectrolytes, zwitterionic polyelectrolytes are stable over a broad pH range from 1 to 13, even in 1 M NaCl solution. The absence of FRET between zwitterionic polymers and dye-labeled ssDNA indicates their ultralow nonspecific adsorption, while cationic polymer shows much stronger nonspecific interactions. The MTT assay of zwitterionic polymers exhibits their minimal cytotoxicity and potential in long-term clinical application. Most importantly, zwitterionic polymer could be efficiently taken up by cells, whereas cationic polymer stains the surface of cell due to membrane disruption generated from positive charges. The results illustrate that conjugated zwitterionic polymer could serve as a novel type of highly efficient ultralow fouling material with low cytotoxicity for labelling cell or potential biomedical applications.
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  • 43
    Publication Date: 2020
    Description: The increasing common occurrence of antibiotic-resistant bacteria has become an urgent public health issue. There are currently some infections without any effective treatment, which require new therapeutic strategies. An attractive alternative is the design of compounds capable of disrupting bacterial communication known as quorum sensing (QS). In Gram-negative bacteria, such communication is regulated by acyl-homoserine lactones (AHLs). Triggering of QS after bacteria have reached a high cell density allows them to proliferate before expressing virulence factors. Our group previously reported that hexyloxy phenylimidazoline (9) demonstrated 71% inhibitory activity of QS at 100 μM (IC50 = 90.9 μM) in Chromobacterium violaceum, a Gram-negative bacterium. The aim of the present study was to take 9 as a lead compound to design and synthesize three 2-imidazolines (13–15) and three 2-oxazolines (16–18), to be evaluated as quorum-sensing inhibitors on C. violaceum CV026. We were looking for compounds with a higher affinity towards the Cvi receptor of this bacterium and the ability to inhibit QS. The binding mode of the test compounds on the Cvi receptor was explored with docking studies and molecular dynamics. It was found that 8-pentyloxyphenyl-2-imidazoline (13) reduced the production of violacein (IC50 = 56.38 μM) without affecting bacterial growth, suggesting inhibition of quorum sensing. Indeed, compound 13 is apparently one of the best QS inhibitors known to date. Molecular docking revealed the affinity of compound 13 for the orthosteric site of N-hexanoyl homoserine lactone (C6-AHL) on the CviR protein. Ten amino acid residues in the active binding site of C6-AHL in the Cvi receptor interacted with 13, and 7 of these are the same as those interacting with AHL. Contrarily, 8-octyloxyphenyl-2-imidazoline (14), 8-decyloxyphenyl-2-imidazoline (15), and 9-decyloxyphenyl-2-oxazoline (18) bound only to an allosteric site and thus did not compete with C6-AHL for the orthosteric site.
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  • 44
    Publication Date: 2020
    Description: Adsorption of SO2 on pure B12P12 and Zn-doped B12P12 is investigated through density functional theory methods. Zn adsorption on BP delivers four optimized geometries: B-Top, P-top, b64, and ring-enlarged geometry with adsorption energies of −57.12 kJ/mol, −14.50 kJ/mol, −22.94 kJ/mol, and −14.83 kJ/mol, respectively. The adsorption energy of SO2 on pristine boron phosphide is −14.92 kJ/mol. Interaction of SO2 with Zn-doped boron phosphide gives four different geometries with adsorption energies of −69.76 kJ/mol, −9.82 kJ/mol, −104.92 kJ/mol, and −41.87 kJ/mol. Geometric parameters such as dipole moment, QNBO, frontier molecular orbital analysis, PDOS, and global indices of reactivity are performed to visualize the changes in electronic properties of B12P12 after Zn and SO2 adsorption.
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  • 45
    Publication Date: 2020
    Description: Rice stem borer, Chilo suppressalis, is a common and major serious pest of rice, maize, and wheat crops across Asia, Europe, and Oceania countries. Its sex pheromone consists of three analogously compounds, i.e., (Z)-hexadec-11-enal (1), (Z)-octadec-13-enal (2), and (Z)-hexadec-9-enal (3), as long-chain aliphatic internal cis-alkenyl aldehydes. In order to perform an economic and widespread pest control management of rice stem borer, a versatile and efficient synthetic strategy is required. A versatile and efficient synthesis using a common synthetic route for cis-alkenals with high overall yields is described. Commercially available inexpensive aliphatic diols were chosen as starting materials. Two key steps were employed to synthesize the long-chain aliphatic internal cis-alkenes in excellent yields, including the alkylation of terminal alkynes without the utilization of a highly polar aprotic cosolvent and the versatile cis-selective semihydrogenation for the reduction of internal alkynes with excellent stereoselectivity. The results of field tests showed that the synthetic sex pheromone blend was highly effective for the capture of rice stem borer.
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  • 46
    Publication Date: 2020
    Description: Guerbet amine-oxide was synthesized by using Guerbet acid, N,N′-diethyl-1,3-propanediamine and hydrogen peroxide. Its structure was confirmed by FT-IR spectra and mass spectra. The critical micelle concentration (CMC) and the interfacial tension between the crude oil and water were measured. The results showed that the CMC of the Guerbet amine-oxide is 2.14 × 10−5 mol/L and the interfacial tension could be lowered to ultralow levels. The core flood test showed that the surfactant and polymer binary system could increase oil recovery by 24.7% above the water flood.
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  • 47
    Publication Date: 2020
    Description: This study explored the possible use of a microbial carboxymethylated sulfated heteroexopolysaccharide (CS-hEPS) as a potential anticancer agent. The investigation was carried out through antioxidant, antifatigue, and antiproliferative activities. Antioxidant potential including scavenging DPPH and hydroxyl radical activities and reducing power was evaluated. Antifatigue activity was determined by assessing the endurance of mice using the forced swimming test. Following 30 days of CS-hEPS oral treatment at different doses, biochemical parameters related to fatigue such as lactic dehydrogenase (LDH), serum urea nitrogen (SUN), and hepatic glycogen (HG) contents were measured. Antitumor activities were investigated against human cancer liver and myelogenous leukemia cells. Results showed that CS-hEPS possesses notable antioxidant, antifatigue, and antitumor effects. CS-hEPS significantly inhibited the proliferation of leukemia (86.6 ± 0.32%) and cancer liver (58.6 ± 0.43%) cells. CS-hEPS are promising natural antioxidant, antifatigue, and antitumor harmless adjuvant materials that could be applied in human cancer therapy.
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  • 48
    Publication Date: 2020
    Description: Micro-combustor can provide the required thermal energy of micro-thermal photovoltaic (MTPV) systems. The performance of MTPV is greatly affected by the effectiveness of a micro-combustor. In this study, a numerical simulation was conducted to explore the benefits of annular rectangular rib for enhancing the thermal performance of a nonpremixed micro-combustor. Based on the investigations under various rib heights, rib positions, and inlet mass flow rates, it is found that the addition of annular rectangular ribs in the micro-combustor creates a turbulent zone in the combustion chamber, thereby enhancing the heat transfer efficiency between the inner wall of the combustion chamber and the burned gas. The micro-combustor with annular rectangular rib shows a higher and more uniform wall temperature. When the H2 mass flow is 7.438 × 10−8 kg/s and the air mass flow is 2.576 × 10−6 kg/s, the optimum dimensionless rib position is at l = 6/9 and r = 0.4. At this condition, the micro-combustor has the most effective and uniform heat transfer performance and shows significant decreases in entropy generation and exergy destruction. However, the optimum l and r significantly depend on the inlet mass flow of H2/air mixture.
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  • 49
    Publication Date: 2020
    Description: The high content of chlorine in biomass will cause serious ash deposition and corrosion problems on the heating surface in boiler, reduce heat transfer efficiency, and endanger the boiler operation safety. On the basis of discussing the mechanism of chlorine corrosion to heating surface in the boiler, the temperature, atmosphere, and fouling in the boiler are simulated by high-temperature reaction device. Reaction kinetics of chlorine corrosion to heating surfaces during coal and biomass cofiring was studied by the weight gain method, which provides a theoretical basis for solving the problem of corrosion and improving the safety of boiler operation. The results show that the weight gain caused by corrosion increases with time, and its curve is in accordance with the parabola. In the early stage, the corrosion rate is very fast, and the corrosion gradually slows down after the protective layer is formed. The mixing ratio of straw biomass increases, and the corrosion rate increases proportionally. With the increase in temperature, the rate of corrosion reaction increases continuously. When the temperature exceeds 600°C, the corrosion reaction rate increases greatly. The concentration of HCl in the gas phase increases and the rate of corrosion reaction increases rapidly. Under the constant temperature, the reaction kinetics characteristics of chlorine corrosion were analyzed by model function matching. The best kinetic model function for calculating the kinetic parameters was determined, and the kinetic equation of corrosion reaction was established to quantitatively characterize the corrosion reaction.
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  • 50
    Publication Date: 2020
    Description: Objective. To establish a method for analysis of microelements in five kinds of traditional Chinese medicine in high blood pressure medicinal food, mainly including manganese, cobalt, selenium, iron, magnesium, and other 15 elements. Methods. The samples were digested using a microwave digestion instrument through NHO3-H2O2 solution, and then, the elements were synthesized by inductively coupled plasma atomic emission spectrometry (ICP-AES). Results. The content of cobalt, manganese, zinc, copper, and nickel in the high blood pressure diet foods is higher, the RSD is between 0.005% and 4.82%, and the recovery rate ranges from 93.40% to 106.5%. The precision and recovery of the detection method are higher. Conclusion. The experiment result is better. Medicinal foods curing high blood pressure contain a number of micronutrients that are beneficial to the human body. This experiment provides some meaningful basis for the prevention and treatment of cardiovascular diseases such as hypertension.
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  • 51
    Publication Date: 2020
    Description: Two cholesterol secosterol aldehydes, namely, 3β-hydroxy-5-oxo-5,6-secocholestan-6-al (secosterol A) and its aldolization product 3β-hydroxy-5β-hydroxy-B-norcholestane-6β-carboxyaldehyde (secosterol B), are highly bioactive compounds which have been detected in human tissues and potentially contribute to the development of physiological dysfunctions such as atherosclerosis, Alzheimer’s disease, diabetes, and cancer. They were originally considered to be exclusive products of cholesterol ozonolysis and thus to be evidence for endogenous ozone formation. However, it was recently postulated that primary amines such as lysine may catalyse their formation from cholesterol-5α-hydroperoxide (Ch-5α-OOH), the main product of the oxidation of cholesterol with singlet oxygen. This involves cyclization of Ch-5α-OOH to an unstable dioxetane intermediate, which decomposes to form secosterol aldehydes with triplet carbonyl groups, whose return to the singlet state is at least partly coupled to the conversion of triplet molecular oxygen to singlet oxygen. Here, we subjected cholesterol to photosensitized oxidation, which predominantly produces Ch-5α-OOH and minor amounts of the 6α- and 6β-hydroperoxides, exposed the hydroperoxide mixture to lysine in the presence of the antioxidant 2,6-ditertiary-butyl-4-hydroxytoluene (BHT), and analysed the reaction mixture by liquid chromatography-electrospray ionization-mass spectrometry. Consistent with the postulated lysine-catalysed formation of secosterol aldehydes, we detected formation of the latter and several types of their lysine adducts, including carbinolamines, Schiff’s bases, and amide-type adducts. We propose that the amide type adducts, which are major biomarkers of lipid oxidation, are mainly formed by singlet oxygen-mediated oxidation of the carbinolamine adducts.
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  • 52
    Publication Date: 2020
    Description: Waste black tea powder was used as a potential adsorbent to remove methylene blue (MB) from aqueous solution. Several operating factors in adsorption of MB onto waste black tea powder were investigated, including contact time, initial MB concentration, solution pH, adsorption temperature, and dosage of waste black tea powder. Experimental results revealed that the adsorption efficiency increased with contact time and solution pH values and decreased with initial MB concentration and adsorption temperature. The equilibrium time was estimated to be around 60 min. The maximum adsorption capacity and the highest adsorption efficiency were 302.63 mg·g−1 and 100%, respectively. In kinetic study, pseudo-first-order and pseudo-second-order kinetic models, intraparticle diffusion model, and Boyd and Elovich models were employed to analyze the adsorption behavior and the adsorption mechanism. It was found that the pseudo-second-order kinetic model was suitable to describe the adsorption process, and the calculated equilibrium adsorption capacity was well close to the experimental data for different initial MB concentrations. The internal diffusion was not the only rate-controlling step, and the existence of boundary effect was observed in this study. From isotherm analysis, the equilibrium data were well represented by the Langmuir model, rather than Freundlich, Dubinin–Redushckevich, or Temkin models. The nonlinear fitting for various isotherm models implied that the adsorption behavior between MB and waste black tea powder was complication. Thermodynamic parameters including changes in Gibb’s free energy, enthalpy, and entropy suggested that adsorption of MB onto waste black tea powder was a spontaneous and exothermic process. The multiple regeneration/adsorption experiments indicated that the used black tea powder efficiently remained more than 75% after five cycles using NaOH as a regenerative reagent and thus be used for many times. Therefore, as a low-cost and easily available material, waste black tea powder could be applied in wastewater treatment.
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  • 53
    Publication Date: 2020
    Description: Potential energy surface scanning for UC, UN, and UH was performed by configuration interaction (CI), coupled cluster singles and doubles (CCSD) excitation, quadratic configuration interaction (QCISD (T)), and density functional theory PBE1 (DFT-PBE1) methods in coupling with the ECP80MWB_AVQZ + 2f basis set for uranium and 6 − 311 + G for carbon, hydrogen, and nitrogen. The dissociation energies of UC, UN, and UH are 5.7960, 4.5077, and 2.6999 eV at the QCISD (T) levels, respectively. The calculated energy was fitted to the potential functions of Morse, Lennard-Jones, and Rydberg by using the least square method. The anharmonicity constant of UC is 0.0047160. The anharmonic frequency of UC is 780.27 cm−1 which was obtained based on the PBE1 results. For UN, the anharmonicity constant is 0.0049827. The anharmonic frequency is 812.65 cm−1 which was obtained through the PBE1 results. For UH, the anharmonicity constant is 0.017300. The anharmonic frequency obtained via the QCISD (T) results is 1449.8 cm−1. The heat capacity and entropy in different temperatures were calculated using anharmonic frequencies. These properties are in good accordance with the direct DFT-UPBE1 results (for UC and UN) and QCISD (T) results (for UH). The relationship of entropy with temperature was established.
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  • 54
    Publication Date: 2020
    Description: Unilameller nanosheets with a lateral dimension of one nanometer have been isolated from a colloidal solution of europium-containing layered rare-earth hydroxide (LRH) material by the flocculation method. The nanosheets were achieved by changing pH of the colloidal solution from 6.7 to 11.5. The resultant flocculated nanosheets show high efficiency in sorption of fluoride anions from aqueous media (40 mmol/g), providing a potentially useful sorbent material for water purification technology. The sorbent material is demonstrated to be reusable for at least ten times without a significant loss of adsorption efficiency. And the results fit the Langmuir adsorption curve, indicating the chemisorption nature of the nanosheets. Most importantly, the isolated nanosheets are expected to widen the applicability and flexibility in material synthesis using two-dimensional nanomaterials.
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  • 55
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    Unknown
    Hindawi
    Publication Date: 2020
    Description: Incident tissue-damaging factors trigger a systemic response manifested by inflammatory reaction. Acute-phase proteins are a diagnostic and prognostic marker in various systemic homeostasis disorders. In the course of health resort therapy, a so-called health resort reaction is observed presenting with, e.g., exacerbation of organ-related disorders, elevated body temperature, increased erythrocyte sedimentation rate, and leukocyte counts. The objective of the study was to demonstrate a change in the concentration of C-reactive protein (CRP) as a result of health resort radon therapy as well as to determine the relationship between this change and the phenomenon known as health resort reaction. The study was conducted in Swieradow-Zdroj resort. The study population consisted of patients undergoing radon-active water bath treatment. Standard tests were used to determine CRP levels before the treatment as well as 5 and 18 days into the treatment. The study group consisted of n = 34 patients with osteoarthritis and spondyloarthritis. The control group consisted of 17 employees of the health resort who were also burdened with osteoarthritis or spondyloarthritis yet did not undergo radon therapy and had absolutely no contact with radon materials. The study revealed no statistically significant increase in the concentration of CRP. This trial is registered with NCT03274128. The study was carried out as part of the statutory task SUB.E060.19.001.
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  • 56
    Publication Date: 2020
    Description: Hydrogenation of bio-based furfural (FUR) to furfuryl alcohol (FFA) is tremendously expanding the application of biomass in many industries such as resins, biofuels, and pharmaceuticals. However, mass manufacture of FFA from FUR is restrained by strict requirements of reaction conditions and expensive catalysts. In this work, an economical and benign catalytic system, containing an easily prepared and reusable catalyst 5 wt.% KF/ZrO2 and a low-cost hydrogen source polymethylhydrosiloxane (PMHS), was developed to be efficient for the hydrogenation of FUR to high-value FFA under mild conditions. The catalyst reactivity was found to be remarkably influenced by the support acid-base properties and KF loading doge. In the presence of 5 wt.% KF/ZrO2, a high FFA yield of 97% and FUR conversion of 99% could be obtained at 25°C in just 0.5 h, which was superior to those attained with other tested catalysts. The KF/ZrO2 catalyst could be recycled at least five times, with the FFA yield slightly decreasing from 97% to 71%. The spare decrease in FFA yield is possibly attributed to the catalyst pore blocking, as clarified by SEM, BET, XPS, and ICP-MS measurements of the fresh and reused catalysts.
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  • 57
    Publication Date: 2020
    Description: This study deals with the removal of residual pollutants from tanning wastewater by continuous adsorption mechanism, using local sand as a low-cost adsorbent. The possibility of pretreating a complex tannery effluent heavily loaded with a natural material such as sand is significant. The characterization of the adsorbent before and after continuous adsorption was performed by X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. Column studies were also carried out to evaluate the performance of the adsorbent and the efficiency of column adsorption. The adsorption kinetic rate seems to be strongly influenced by certain parameters such as the particle size of the material used, the withdrawal rate of the influent and the height of the adsorbent bed, and optimized parameters were found to be 63 μm, 15 ml·min−1, and 7 cm, respectively, and the color removal has achieved maximum values which vary between 95 and 100%. The results suggest that sand can be used as an economical adsorbent for the removal of color from the wastewater of the tanning industries.
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  • 58
    Publication Date: 2020
    Description: The recombinant thyroid hormone receptor (TR) gene yeast assay was used to evaluate thyroid disruption caused by groundwater from the riverbank filtration (RBF) system in Wuchang City, China. To investigate seasonal fluctuations, groundwater was collected during three seasons. Although no TR agonistic activity was found, many water samples exhibited TR antagonistic activity. The bioassay-derived amiodarone hydrochloride (AH) equivalents ranged from 2.99 to 274.40 μg/L. Water samples collected from the riverbank filtration system during the dry season had higher TR antagonistic activity. All samples presented adverse 3,3′,5-triiodo-L-thyronine (T3) equivalent levels, ranging from −2.00 to −2.12 μg/kg. Following exposure to water samples with substantial TR antagonist activity, predicted hormonal changes in humans of different gender and age ranged from 0.65 to 1.48 μg/kg of T3, being 47% to 231% of normal. No obvious difference was found between genders or among age groups. Overall, the results revealed that the RBF system could remove the thyroid-disrupting chemicals in the river water to some extent. Considering the varying degrees of risk to human health, further treatment is needed to remove the potential thyroid-disrupting chemicals in pumping water after riverbank filtration to ensure drinking water safety.
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  • 59
    Publication Date: 2020
    Description: Three lignans (1–3) and three butanolides (4–6) were isolated from the lipophilic extract of the Cinnamomum camphora stem bark. The six compounds were identified as (-)-sesamin (1), 9α-hydroxysesamin (2), 9β-hydroxysesamin (3), obtusilactone A (4), isoobtusilactone A (IOA, 5), and isomahubanolide (6) from their spectroscopic data. Four (1, 2 and 5, 6) of them were evaluated for their repellent and feeding deterrent activities against Tribolium castaneum. In this work, the three butanolides (4–6) were confirmed to exist in C. camphora for the first time. Results of bioassays indicated that (-)-sesamin (1), IOA (5), and isomahubanolide (6) displayed certain repellent activities against T. castaneum at 78.63, 15.73, and 3.15 μg/cm2 at 2 h after exposure. Among the three compounds, (-)-sesamin (1) and IOA (5) exerted stronger effects and maintained longer duration of repellency. Furthermore, IOA (5) and isomahubanolide (6) showed good feeding deterrent activity against T. castaneum. IOA (5) was still potently active at low concentrations with the feeding deterrence index (FDI) ranging from 42.85% to 50.66% at 15–1500 ppm. This work provides some evidence for explaining antiinsect properties of the nonvolatile fraction of the C. camphora stem bark and helps promote the development and comprehensive utilization of this tree species.
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  • 60
    Publication Date: 2020
    Description: The explosion pressure and minimum explosible concentration (MEC) properties of metal sulfide ore dust clouds are valuable for the prevention and control of metal sulfide ore dust explosions. In this study, a 20 L explosion sphere vessel was used to investigate the effect of sulfur content, particle size, and concentration on the explosion pressure and minimum explosible concentration of metal sulfide ore dust clouds. Four samples with different sulfur contents were selected (30%–40%, 20%–30%, 10%–20%, and 0%–10%). Before and after the explosion, samples were tested by X-ray diffraction. The results indicate that the metal sulfide ore dust is explosive dust with St1 grade explosion pressure. With an increase in concentration, the maximum explosion pressure increased at first and then decreased. With an increase in sulfide content, the explosion pressure of metal sulfide ore dust increased, while the minimum explosible concentration decreased. As particle size decreased, the MEC also decreased. The sulfur content, particle size, and concentration of metal sulfide ore dust were the main factors affecting the explosion hazard.
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  • 61
    Publication Date: 2020
    Description: Antibacterial agents are a group of materials that selectively destroy bacteria by interfering with bacterial growth or survival. With the emergence of resistance phenomenon of bacterial pathogens to current antibiotics, new drugs are frequently entering into the market along with the existing drugs, and the alternative compounds with antibacterial functions are being explored. Due to the advantages of their inherent biochemical and biophysical properties including precise targeting ability, biocompatibility, biodegradability, long blood circulation time, and low cytotoxicity, biomolecules such as peptides, carbohydrates, and nucleic acids have huge potential for the antimicrobial application and have been extensively studied in recent years. In this review, antimicrobial therapeutic agents composed of three kinds of functional biological molecules were summarized. In addition, the research progress of antibacterial mechanism, chemical modification, and nanoparticle coupling of those biomolecules were also discussed.
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  • 62
    Publication Date: 2020
    Description: Cell wall degrading enzymes break down the cell wall by degrading the main cell wall components and destroying structure of the cell wall without influencing the protein. Effects of various enzymes (Viscozyme® L, cellulase, hemicellulase, and pectinase) on the molecular weight distribution of peanut protein and yield of peanut protein and oil bodies during an aqueous enzymatic extraction process were investigated in this study. The molecular weight distribution of peanut protein was not changed, and Viscozyme® L was selected to assist peanut protein and oil bodies extraction by the aqueous extraction process. The aqueous enzymatic extraction process was optimized by a signal factor experiment and response surface methodology, and the optimal condition was enzyme hydrolysis temperature of 52°C, solid-liquid ratio of 1 : 4, enzyme concentration of 1.35%, and enzyme hydrolysis time of 90 min. A peanut protein yield of 78.60% and oil bodies yield of 48.44% were achieved under the optimal condition. Compared with commercial peanut protein powder (CPPP), the solubility and foaming properties of peanut protein powder obtained by aqueous enzymatic extraction (AEEPPP) were a little lower. However, the functional properties of foam stability, emulsifying activity, emulsifying stability, water holding capacity, and oil holding capacity of AEEPPP were better than that of CPPP.
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  • 63
    Publication Date: 2020
    Description: 1,1-diamino-2,2-dinitroethene (FOX-7) is a novel explosive with low sensitivity and high performance. The compatibility of FOX-7 with nine common energetic materials including hexanitrohexazaisowurtzitane (CL-20), cyclotetramethylenetetranitramine (HMX), cyclotrimethylenetrinitramine (RDX), 3,4-dinitrofurazanfuroxan (DNTF), 3-nitro-1,2,4-triazol-5-one (NTO), hexanitrostilbene (HNS-II), 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105), 2,4,6-triamino-1,3,5-trinitrobenzene (TATB), and 2,4,6-trinitrotoluene (TNT) were tested by differential scanning calorimetry (DSC) and the vacuum stability test (VST) as the thermal technique and X-ray diffractometry (XRD) as a nonthermal technique. DSC measurements showed that the binary systems of FOX-7/CL-20, FOX-7/HMX, FOX-7/NTO, and FOX-7/TNT were compatible in grade of A, the systems of FOX-7 with heat-resistant explosives including HNS-II, LLM-105, and TATB were compatible as well in grade of A-B, and the binary systems of FOX-7/DNTF and FOX-7/RDX had poor compatibility. VST results indicated that FOX-7 was compatible with nine energetic materials. Besides, the compatibility results of the thermal analysis were confirmed by the XRD technique.
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  • 64
    Publication Date: 2020
    Description: Nephelium lappaceum and its by-products have great potential in the agricultural, pharmaceutical, and food industries. Some studies have shown that N. lappaceum by-products exhibit antimicrobial, antioxidant, antidiabetic, and anticancer properties. However, studies focused on identifying these compounds are rare. The availability of polyphenolic compounds can vary according to environmental conditions, soil, plant variety, and agronomic management. Therefore, in this study, the active compounds in extracts of the N. lappaceum peel were identified, and their antioxidant properties were evaluated using various extraction solvents and both ultrasonic and boiling extraction techniques. The chemical characterization of the N. lappaceum peel exhibited carbohydrate and reducing sugar contents of 12 and 2%, respectively. Phytochemical analysis indicated the presence of flavonoids, tannins, terpenes, and steroids. The total phenolic and flavonoid contents and total antioxidant capacity were the highest in the hydroethanolic extract obtained by ultrasound, with values of 340 mg gallic acid equivalents g−1, 76 mg quercetin equivalents g−1, and 2.9 mmol of Trolox equivalents g−1, respectively. Contrarily, the total anthocyanin content was higher in the acid extract obtained by ultrasound, with a value of 0.7 mg cyanidin-3-O-glucoside equivalents g−1. A total of 18 compounds—including hydroxybenzene, phenolic acid, flavonoids, fatty acids (saturated, unsaturated, and ester), vitamin, arenecarbaldehyde, and phthalate—were identified for the first time in the N. lappaceum peel using gas chromatography-mass spectrometry. The identified compounds have been previously isolated from other plants and reportedly exhibit anticancer, anti-inflammatory, antimicrobial, and antioxidant activities. Thus, the N. lappaceum peel was shown to be a potential source of bioactive compounds of immense importance in the pharmacological and food industries.
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  • 65
    Publication Date: 2020
    Description: Fresh water scarcity and pollution turn out to be a most serious issue throughout the world due to the rapid population growth. The application of nanomaterials (NMs) for the removal of pollutants from water has attracted significant attention. The nanofiltration membrane was fabricated through the evaporative casting (EC) method using multiwalled carbon nanotubes (MWCNT) and chitosan (CHIT) as the surfactant to enable water purification. The developed EC membrane properties were characterized in mechanical, surface charging (zeta potential), surface morphology, and hydrophobicity properties. Results demonstrated that incorporation of MWCNT and the biopolymers (chitosan) resulted in suitable developments in mechanical properties of the membrane. For example, the membrane has shown values for tensile strength (28 ± 1 MPa), elongation (10.2 ± 1.2%), Young’s modulus (1.2 ± 0.1 GPa), and toughness of (1.9 ± 0.2 J/g). When more significant changes were investigated on the surface morphology of the EC membrane, it was observed that the pores on the surface morphology of the EC membrane decreased as the evaporative casting method was used. Moreover, the permeability of the membrane towards water, inorganic salts, and pH effect on salt rejections was studied using the NF/RO system. These established nanocomposite membranes signify the promising candidates for fresh water desalination and elimination of organic impurities.
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  • 66
    Publication Date: 2020
    Description: Co-Ag supported on the SiO2 catalyst was synthesized by the sol-gel method and characterized using XRD, FT-IR, TG-DTG, BET, CV, and SEM/EDX analysis. The catalytic performance of the resulting catalyst was examined by the oxidation of mono and sesquiterpenic olefins using hydrogen peroxide and tert-butyl peroxide as oxidant agents. Various parameters such as catalyst amount, temperature, and solvents have been studied. The Co-Ag supported on the SiO2 catalyst showed a high activity, selectivity, and recyclability for the selected oxidation reaction.
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  • 67
    Publication Date: 2020
    Description: In order to investigate the regularity and mechanism of corrosion related to ash deposition on the boiler heating surface during cofiring of coal and biomass, the influence of fuel property, type of metal tubes (heating surface), proportion of blended biomass, and atmosphere in the furnace was studied by using the static corrosion mass gain method with the high-temperature tube furnace system. The results indicated that the effect of biomass property on ash corrosion is greater than that of coal, which was mainly due to high content of alkali metals and chlorine in biomass fuels. The corrosion resistance of metal pipes is T91 〉 12CrMoVG 〉 20G. T91 is the most appropriate one, and it can effectively inhibit chlorine corrosion and can be used as the ideal material for the biomass-fired boiler and the biomass and coal cofired boiler. In addition, ash deposition can significantly aggravate the corrosion of metal tubes, and the degree of corrosion tends to become significant with increasing proportion of blended biomass fuels. HCl can aggravate metal corrosion, which can be inhibited by SO2.
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  • 68
    Publication Date: 2020
    Description: Densities of sodium arsenite (NaAsO2) aqueous solution with the molality varied from 0.19570 to 1.94236 mol·kg−1 at temperature intervals of 5 K from 283.15 to 363.15 K and 101 ± 5 kPa were measured by a precise Anton Paar Digital vibrating-tube densimeter. Apparent molar volumes (VΦ) and thermal expansion coefficient (α) were obtained on the basis of experimental data. The 3D diagram of apparent molar volume against temperature and molality and the diagram of thermal expansion coefficient against molality were generated. According to the Pitzer ion-interaction equation of the apparent molar volume model, the Pitzer single-salt parameters (,,, and , MX = NaAsO2) and their temperature-dependent correlation F(i, p, T) = a1 + a2ln (T/298.15) + a3(T − 298.15) + a4/(620 − T) + a5/(T − 227) (where T is temperature in Kelvin and ai are the correlation coefficients) for NaAsO2 were obtained for the first time. The predictive apparent molar volumes agree well with the experimental values, and those results indicated that the single-salt parameters and the temperature-dependent formula are reliable.
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  • 69
    Publication Date: 2020
    Description: Tetrapleura tetraptera is widely cherished in African traditional homes because of its alleged therapeutic and nutritional properties. This present study aimed at determining the levels of vitamin A, C, E, and beta-carotene and trace element (Fe, Cu, Mn, Co, Se, and Zn) concentrations and their extractabilities in the pulp, seeds, and whole fruit (mixture of pulp and seeds) of T. tetraptera. The total trace element concentration of Fe, Cu, Co, Mn, and Zn and their extractabilities (%) were determined using flame atomic absorption spectrometer (FAAS), whereas UV-VIS spectrophotometer was used to determine selenium concentration. The trace element content (mg/kg) based on dry weight in the pulp, seeds, and whole fruit was Fe (162.00 ± 7.14, 115.00 ± 12.00, and 154.00 ± 25.20, respectively), Zn (31.60 ± 4.77, 43.40 ± 5.29, and 41.50 ± 8.97, respectively), Cu (16.10 ± 4.98, 11.90 ± 8.40, and 17.20 ± 14.50, respectively), Mn (55.30 ± 2.41, 156.00 ± 10.20, and 122.00 ± 5.29, respectively), Co (38.10 ± 6.40, 21.10 ± 7.15, and 44.00 ± 14.90, respectively), and Se (1.49 ± 0.17, 2.43 ± 0.28, and 2.97 ± 0.27 μg/g, respectively). The mineral extractabilities (%) in the pulp, seeds, and whole fruit of T. tetraptera were established to be in the order Co 〉 Zn 〉 Fe 〉 Cu 〉 Se 〉 Mn. Also, the chromatographic method (HPLC) was used to evaluate vitamin E concentration, and vitamin C and concentration of beta-carotene were calculated from the obtained concentration of vitamin A using a conversion factor by the titrimetric method. From the results of vitamin analysis, a significant difference () was observed among the pulp, seeds, and whole fruit for vitamin C and E. However, no significant difference () was perceived among these plant parts for vitamin A and beta-carotene. This study has therefore revealed that the pulp, seeds, and whole fruit of T. tetraptera contain varying concentrations of vitamins and trace elements and has given many vital insights on which part of T. tetraptera to consume, as concentrations of these nutrients differ in the discrete parts of the fruit.
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  • 70
    Publication Date: 2020
    Description: Ethanol is the most extensively used oxygenate for spark ignition (SI) engines. In comparison with ethanol, n-butanol exhibits a number of desirable properties for use in SI engines, which has proved to be a very promising oxygenated alternative fuel in recent years. However, the dehydration and recovery of bio-n-butanol consume extra money and energy in the acetone-n-butanol-ethanol (ABE) fermentation process. Hence, we focus on the research of ABE as a potential oxygenated alternative fuel in SI engines. The combustion, performance, and emission characteristics of B30, E30, ABE30 (i.e., 30 vol.% n-butanol, ethanol, and ABE blended with 70 vol.% gasoline), and G100 (pure gasoline) were compared in this study. The comparison results between B30, E30, and ABE30 at stoichiometric conditions show that ABE30 presents retarded combustion phasing, higher brake thermal efficiency, lower CO emissions, higher UHC emissions, and similar NOx emissions. In comparison with G100 under various engine loads and equivalence ratios, for the most part, ABE30 exhibits 1.4% higher brake thermal efficiency, 14% lower carbon monoxide, 9.7% lower unburned hydrocarbons, and 23.4% lower nitrogen oxides. It is indicated that ABE could be served as the oxygenate in spark ignition engine due to its capability to improve energy efficiency and reduce pollutant emissions.
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  • 71
    Publication Date: 2020
    Description: To elucidate the chemical compositions of Prunus cerasifera Ldb leaves, the methanol extracts were firstly fractionated by ethyl acetate and n-butanol, respectively. The phenolic acid-rich fractions (ethyl acetate extracts) were further isolated by various chromatographic columns (CC) including MCI macroporous resin, normal-phase silica gel, Sephadex gel LH-20, octadecyl silane (ODS), and preparative HPLC to yield the phenolic compounds. The isolated compounds were analyzed by 1H-nuclear magnetic resonance (1H-NMR), 13C-NMR, and electrospray ionization mass spectral (ESI-MS) spectroscopy. Eleven phenolic acids were identified as p-coumaric acid (1), caffeic acid (2), ferulic acid (3), chlorogenic acid (4), 3-O-caffeoylquinic acid (5), 5-O-coumaroylquinic acid (6), 3-O-caffeoylquinic acid methyl ester (7), chlorogenic acid methyl ester (8), 3-O-caffeoyl-5-O-coumaroylquinic acid or 3-O-coumaroyl-5-O-caffeoylquinic acid (9), gallic acid (10), and protocatechuic acid (11). The current study pioneers to identify and report all the phenolic constituents from P. cerasifera Ldb leaves.
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  • 72
    Publication Date: 2020
    Description: The use of enzyme-assisted aqueous extraction to extract soybean oil will produce soy protein hydrolysates (SPH) that have good antioxidant properties but are bitter and hygroscopic. To microencapsulate these hydrolysates, soy protein isolate/maltodextrin mixtures were used as the carrier. The effects of spray-drying and freeze-drying on the bitterness, hygroscopicity, and antioxidant properties were compared. The properties of different dried samples were compared using solubility, hygroscopicity, moisture content, water activity, flowability, and glass transition temperature (Tg). The results showed that the spray-drying was more effective than freeze-drying. Hygroscopicity was reduced to 18.2 g/100 g, and the Tg value was raised to 80.8°C. The morphology was analyzed using scanning electron microscopy, and the antioxidant properties of the samples were measured using the ABTS˙+ radical scavenging activity. The results showed that spray-dried SPH had more carrier masking, which weakened bitterness, reduced moisture absorption, and had no significant negative impact on its oxidation resistance, solubility, and flowability, and spray-drying after carrier encapsulation of SPH improved the recovery rate.
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  • 73
    Publication Date: 2020-04-29
    Description: Reaction term in the transport equation which described the migration of metal ions in the porous medium is frequently represented by conventional kinetic models such as pseudo-first order, pseudo-second order, and others. Unfortunately, these models are applicable for the constant value of solution pH, and they cannot simulate the real situation in the field scale where this pH may be changed with time. Accordingly, the present study is a good attempt to derive the kinetic model that can simulate the change in the pH of the solution through solute transport. This was achieved by modifying the adsorption capacity and reaction constant to be functions in terms of solution pH by using semianalytical analysis and numerical approximation. The results proved that the kinetic model based on the numerical approximation (using exponential functions for adsorption capacity and reaction constant) symbolled as model 2 was more representative from other models applied for the description of interaction of nickel ions (with initial concentration of 400 mg/L) and cement kiln dust with sum of squared error ≤1.54913 and determination coefficient ≥0.889. Also, the developed models had high ability for recognizing between pure precipitation and pure adsorption.
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  • 74
    Publication Date: 2020-04-24
    Description: Diatoms exhibit high solar energy harvesting efficiency due to their remarkably organized, hierarchical micro/nanoporous, light-trapping, and scattering frustules. At present, few studies focus on cosensitization of natural near-infrared dye to expand the spectral response of dye-sensitized solar cells. In this study, the diatom frustule-TiO2 (12 : 5) composite film was prepared and assembled it on the TiO2 electrode. Compared to the single TiO2 layer film, diatom frustule-TiO2 (12 : 5) composite film sensitized by diatom’s dye showed the conversion efficiency of 0.719%. To expand the light-harvesting response to near-infrared region spectra, the cosensitized dyes were used to fabricate the visible-near-infrared responsive dye-sensitized solar cells. The cosensitization diatom frustule-TiO2 (12 : 5) composite film exhibited two distinct absorption bands in the near-infrared region and reached a higher conversion efficiency of 1.321%, which was approximately 1.4 or 1.7 folds higher than that of cosensitization double-TiO2 film or single TiO2 layer film, respectively, and approximately 3.7 or 1.7 folds higher than that of the single TiO2 layer film sensitized by diatom dye or purple bacterial dye, respectively. The results showed that the combination between diatom frustule-TiO2 with cosensitization natural dyes could significantly improve the photoelectric performance of visible-near-infrared responsive dye-sensitized solar cells.
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  • 75
    Publication Date: 2020-04-24
    Description: Lignocellulosic biomass can be used to obtain fermentable sugars by enzymatic hydrolysis, and also it serves as a carbon source to produce cellulases by solid-state fermentation. In this study, we propose the use of leaves of Agave salmiana as a carbon source to produce cellulases by the fungus Penicillium sp., isolated from the same plant. The crude enzymatic extract was used to obtain sugars from the hydrolysis of the parenchymal cells of the leaves. The enzymes produced were characterized (endoglucanase 14.4 U/g; exoglucanase 3.5 U/g; β-glucosidase 4.14 U/g). The enzymes showed activities at elevated temperatures: 50°C for endoglucanase and exoglucanase and 70°C for β-glucosidase. Furthermore, the crude enzymatic extract obtained was able to hydrolyze the parenchyma in 51.6% in 48 h. The evidence presented in this paper shows the potential of the agave leaves as a source of carbon in the production of enzymes by fermentation with the consequent production of reducing sugars. In addition, the enzymes produced by Penicillium sp. could be used in the production of bioethanol, since they work at high temperatures.
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  • 76
    Publication Date: 2020-04-29
    Description: One-pot efficient synthesis of novel chromone derivatives 4a–h and that of 5a–h were described in a simple method via four-component reaction between furochromone carbaldehyde, amine, isocyanate derivatives, and benzoic acid derivatives or nicotinic acid, respectively. Also, oxazocine derivatives 7a, b were prepared via reaction of visnagine carbaldehyde, ethyl acetoacetate and isocyanate derivatives 2a, b. The obtained derivatives of novel furochromone and oxazocine derivatives were evaluated as promising antitumor agents against panel of two human cell lines, hepatocellular carcinoma (HEPG2) and breast carcinoma (MCF7). The antitumor results suggested that furochromone derivatives 5a–h have activity against MCF7 in comparison with doxorubicin as the standard drug. Furthermore, the molecular docking studies of these novel derivatives of furochromone and oxazocine showed good agreement with the biological results when their binding pattern and affinity towards the active site of EGFR was investigate.
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  • 77
    Publication Date: 2020-04-24
    Description: Trihalomethanes (THMs) are formed when excess chlorine during chlorination of water reacts with organic material in water. They have mutagenic and carcinogenic properties. Moringa oleifera (MO) has found wide acceptance by many people in Nigeria who have used it for food for both humans and fauna, for health purposes, and as a coagulant for water treatment. However, the seed husks are currently discarded as waste and they have not been used as adsorbent to remove THMs from water. The physicochemical properties of both the treated and raw surface water were determined using standard methods, and the concentration of THMs was determined from the water treatment plant at different stages of treatment using gas chromatography with flame ionization detector (GC-FID). Recovery experiments were carried out to validate the procedure. The efficiencies of activated carbon of Moringa oleifera seed husk (MOSH) adsorbent for the removal of THMs in the water and as a coagulant for water treatment were also assessed. Batch adsorption experiments were carried out, and different parameters such as pH (5, 7, and 9), adsorbent dosage (0.2, 0.4, and 0.8 g), contact time (30, 60, and 90 minutes), and initial concentration (0.2, 0.4, and 0.6 mg/l) were optimized for the removal of trichloromethane and tribromomethane using the MOSH activated carbon. Experimental adsorption data from different initial concentrations of trichloromethane and tribromomethane were used to test conformity with Langmuir and Freundlich adsorption isotherms. The percentage recovery from our procedures ranged from 96.0 ± 1.41 to 100.0 ± 0.00 for trichloromethane while for tribromomethane the range was 60 ± 2.82 to 100.0 ± 0.00. The mean percentage adsorption efficiencies for the simulation experiment ranged from 34.365 ± 1.41 to 93.135 ± 0.57 and from 41.870 ± 0.27 to 94.655 ± 0.41 for trichloromethane and tribromomethane, respectively. The optimum conditions for both trichloromethane and tribromomethane were pH 9, 0.8 g adsorbent dosage, 60-minute contact time, and 0.6 mg/l initial concentration. The optimum values of these parameters used for the adsorption of the two THMs in the surface water serving the treatment plant gave an efficiency of 100.00 ± 0.00%. The turbidity values for the coagulation experiment reduced from 9.76 ± 0.03 NTU in the raw water before coagulation to 5.92 ± 0.13 NTU after coagulation while all other physicochemical parameters of the surface water decreased in value except conductivity and total dissolved solid which increased from 104.5 ± 3.54 to 108.0 ± 2.83 μS/cm and 63.00 ± 11.31 to 83.0 ± 8.49 mg/l, respectively. The experimental data best fit into Langmuir than Freundlich adsorption isotherm. The study concluded that MOSH activated carbon could serve as an adsorbent for the removal of THMs, calcium, and sulphur from water samples.
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  • 78
    Publication Date: 2020-04-25
    Description: The aim of this study is based on natural clay as an adsorbent in the elimination of polyphenols from olive mill wastewater (OMW). This clay was analyzed using XRD, SEM/EDX, FTIR, surface area measurement (BET method), thermal analysis (TGA/DTA), and X-ray fluorescence (XRF) and then used in adsorption experiments. The results reveal that the best quantity of adsorption of polyphenols is 161 mg/g at the temperature of 25°C, but they decrease at 35°C and 45°C. A great agreement with pseudo-second-order and Freundlich model is represented by kinetic and isotherms models, and several parameters such as ΔG0, ΔS0, and ΔH0 were determined using the thermodynamic function relationship.
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  • 79
    Publication Date: 2020-04-26
    Description: Nanofibril system constructed by protein self-assembly is widely used in the food industry because of purposive functional properties. Soy protein isolate nanofibrils (SPINs) were reported to form via heating at pH 2.0. In this research, the soy protein isolate (SPI) hydrolysate prepared by trypsin was used as a raw material for the formation of nanofibrils called soy protein isolate hydrolysate nanofibrils (SPIHNs). Microscopic images demonstrated the formation of two nanofibrils. Based on circular dichroism spectroscopy and Thioflavin T (ThT) fluorescence spectral, we concluded that β-sheet played an important role in SPIN and SPIHN’s structural composition. At the same time, the α-helix in SPI had not been destroyed, thereby favoring the formation of SPIHN. The surface hydrophobicity of SPIHN continued to increase during the heating process and reached the highest value when heating 8 h. SDS-PAGE analysis showed that peptides produced by enzyme-modified SPI affected the formation of SPIHN. These results proposed that enzymatic hydrolysis prior to acidic during fibrillation process affected the fibrillation of SPI, and the peptides formed by enzymatic hydrolysis were more efficient for the self-assembly process. This study will provide a theoretical basis for the future research of SPI nanofibril functionality.
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  • 80
    Publication Date: 2020-04-24
    Description: Ferric oxide-amine material was synthesized and applied as a novel adsorbent for nitrate and phosphate removal from aqueous solution. The properties of ferric oxide-amine were examined using TGA, FTIR, BET, SEM, EDX, SEM-mapping, and XRD analysis. The results showed that the adsorption using ferric oxide-amine material reached equilibrium after 30 and 60 min for nitrate and phosphate, respectively. The highest nitrate and phosphate adsorption capacities were 131.4 mg nitrate/g at pH 5-6 and 42.1 mg phosphate/g at pH 6. The effects of adsorbent dosage, initial concentrations of nitrate and phosphate, and adsorption temperature were also investigated. Among the three adsorbents of ferric oxide-amine, ferric oxide, and Akualite A420 ion exchange resin, ferric oxide-amine material had the highest adsorption capacity for nitrate and phosphate removal. These results suggest a great potential use of ferric oxide-amine material for water treatment in practical applications.
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  • 81
    Publication Date: 2020
    Description: Ethanol is the most extensively used oxygenate for spark ignition (SI) engines. In comparison with ethanol, n-butanol exhibits a number of desirable properties for use in SI engines, which has proved to be a very promising oxygenated alternative fuel in recent years. However, the dehydration and recovery of bio-n-butanol consume extra money and energy in the acetone-n-butanol-ethanol (ABE) fermentation process. Hence, we focus on the research of ABE as a potential oxygenated alternative fuel in SI engines. The combustion, performance, and emission characteristics of B30, E30, ABE30 (i.e., 30 vol.% n-butanol, ethanol, and ABE blended with 70 vol.% gasoline), and G100 (pure gasoline) were compared in this study. The comparison results between B30, E30, and ABE30 at stoichiometric conditions show that ABE30 presents retarded combustion phasing, higher brake thermal efficiency, lower CO emissions, higher UHC emissions, and similar NOx emissions. In comparison with G100 under various engine loads and equivalence ratios, for the most part, ABE30 exhibits 1.4% higher brake thermal efficiency, 14% lower carbon monoxide, 9.7% lower unburned hydrocarbons, and 23.4% lower nitrogen oxides. It is indicated that ABE could be served as the oxygenate in spark ignition engine due to its capability to improve energy efficiency and reduce pollutant emissions.
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  • 82
    Publication Date: 2020
    Description: In this study, concentrations, sources, and ecological risk of 16 polycyclic aromatic hydrocarbons (PAHs) in 41 surface water samples collected from Wuhai and Lingwu sections of the Yellow River were investigated. The results showed that total PAH concentrations varied from 27.5 ng/L to 234 ng/L and from 135 ng/L to 265 ng/L in surface water of Wuhai and Lingwu sections, respectively. Source identification was performed by using principal component and multiple linear regression analysis. PAHs in Wuhai section of the Yellow River were mainly from coal combustion (35%) and vehicle exhausts (34%). Ecological risk of PAHs to aquatic organisms was assessed by applying the probabilistic risk assessment method. The results showed that the probabilities of exceeding the chronic toxicity for 5% of the species were 28% and 32% for PAHs in surface water from Wuhai and Lingwu sections, respectively. It has been demonstrated that there is an urgent need for environmental managers to take measures to reduce the ecological risk of PAHs in the aquatic environment in both Wuhai and Lingwu sections of the Yellow River.
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  • 83
    Publication Date: 2020
    Description: This paper reports the molar heat capacities of β-CsB5O8·4H2O, which were measured by an accurate adiabatic calorimeter from 298 to 373 K with a heating rate of 0.1 K/min under nitrogen atmosphere. Neither phase transition nor thermal anomalies were observed. The molar heat capacity against temperature was fitted to a polynomial equation of Cp,m (J·mol−1·K−1) = 618.07702 + 39.52669[T − (Tmax + Tmin)/2]/(Tmax − Tmin)/2] − 3.46888[(T − (Tmax + Tmin)/2)/(Tmax − Tmin)/2]2 + 7.9441[(T − (Tmax+ Tmin)/2)/(Tmax − Tmin)/2]3. The relevant thermodynamic functions of enthalpy (HT − H298.15), entropy (ST − S298.15), and Gibbs free energy (GT − G298.15) of cesium pentaborate tetrahydrate from 298 to 375 K of 5 K intervals are also obtained on the basis of relational expression equations between thermodynamic functions and the molar heat capacity.
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  • 84
    Publication Date: 2020
    Description: Karst water in northern China is an important water source for economic and social development in its distribution area and water source for ecological function guarantee. With the enhancement of human activities, the water quality of karst water in the north has deteriorated and the bearing capacity of economic activities and social and ecological environment has weakened. The study on the distribution characteristics and source analysis of toxic substances in typical karst springs in northern China is of great practical significance for the sustainable development of karst areas in northern China. Based on the abundant karst water samples, the concentration, detection, and spatial distribution of toxic heavy metals and typical organic substances in karst waters were analyzed, the quality was evaluated, and the source of substances was analyzed. The results show that the toxic substances in karst water in Jinan are mainly distributed in the northern part of the Jinan urban karst water subsystem and Baiquan karst water subsystem in Jinan city, and the detection rate is low in other areas. The main distribution areas of toxic substances in karst water are the northeast and southwest parts of Jinan city. In the recharge area and runoff area of the karst spring area, the contribution rate of toxic substances to the comprehensive quality evaluation of karst water is relatively low and relatively high in the drainage area of the spring area. The organic index contributes more to the comprehensive quality evaluation of karst water. The distribution of toxic substances is related to the historical and current industrial layouts, and industrial discharge or leakage is the primary source of pollutants in karst water. The concentration of toxic substances in karst water has persistence and inheritance. This study enriches the research results on the distribution and sources of toxic substances in typical karst springs in northern China and provides essential data support for scientific understanding of the changes in karst water quality and optimization of water resource management in northern China.
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  • 85
    Publication Date: 2020
    Description: Dendrimers are highly branched organic macromolecules with successive layers of branch units surrounding a central core. Some properties like toxicity, entropy, and heats of vaporization of these dendrimers can be forecasted using topological indices. The present article is devoted to study of irregularity indices of three well-known classes of dendrimers, namely, nanostar dendrimer D[p], fullerene dendrimer NS4[p], and polymer dendrimerNS5[p], where is the step size. We also see the relation of irregularity of these dendrimers on the step size graphically.
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  • 86
    Publication Date: 2020
    Description: In this study, an effective technique is presented for solving nonlinear Volterra integral equations. The method is based on application of cardinal spline functions on small compact supports. The integral equation is reduced to a system of algebra equations. Since the matrix for the system is triangular, it is relatively straightforward to solve for the unknowns and an approximation of the original solution with high accuracy is accomplished. Several cardinal splines are employed in the paper to enhance the accuracy. The sufficient condition for the existence of the inverse matrix is examined, and the convergence rate is analyzed. We compare our method with other methods proposed in recent papers and demonstrated the advantage of our method with several examples.
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  • 87
    Publication Date: 2020
    Description: The present work aims to study the affinity of a component of the thyme essential oil “thymol” to natural Moroccan clay “Rhassoul” using the adsorption technique. The physicochemical characterizations of the purified and modified clay were carried out by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), DTA/TGA, and SEM-EDX. Thymol adsorption tests on the purified Rhassoul (Rh-P) and the modified one by CTAB (Rh-CTAB) were followed by UV-visible spectroscopy. They show that the adsorption isotherms can be described by the Freundlich model and that the kinetics of adsorption is in accordance with the pseudo-second-order model for the two clays. Adsorption capacities obtained were of the order of 6 mg/g for the purified Rhassoul and 16 mg/g for the modified Rhassoul by cetyltrimethylammonium bromide (CTAB). These values show that the modified Rhassoul has a better adsorption capacity compared to the purified Rhassoul.
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  • 88
    Publication Date: 2020-04-21
    Description: Organophosphorus compounds are organic compounds widely employed in agriculture as well as in chemical weapons. The use in agriculture is due to their insecticidal properties. However, in chemical warfare, the use of organophosphorus is associated with acetylcholinesterase inhibition, which promotes the cholinergic syndromes. In this line, the fast detection of this class of compound is crucial for the determination of environmental exposure. This improved detection will naturally allow for more prompt courses of treatment depending on the contaminant findings. In this perspective, the dipyrrinone oxime (1) was employed for the detection of organophosphorus compounds that are employed as nerve agents, such as cyclosarin, sarin, soman, diethyl chlorophosphate, diisopropylfluorophosphate, 2-(dimethylamino)ethyl N,N-dimethylphosphoramidofluoridate, O-ethyl-S-[2-(diethylamino)ethyl]methylphosphonothioate, O-ethyl-S-[2(diisopropylamino)ethyl] methylphosphonothioate, and O,O-diethyl-S-[2-(diethylamino)ethyl] phosphorothioate, through fluorescent emission. The thermodynamics and kinetic parameters as well as spectroscopic properties of the complexes formed for 1 and all organophosphorus compounds previously cited were investigated by means of theoretical calculations. From our findings, only the diethyl chlorophosphate, 2-(dimethylamino)ethyl N,N-dimethylphosphoramidofluoridate, and O,O-diethyl-S-[2-(diethylamino)ethyl] phosphorothioate emitted fluorescence in the hexane, toluene, chloroform, dichloromethane, methanol, acetonitrile, water, and dimethyl sulfoxide solvents. The study of the absorption wavelength with the most polar solvent showed higher values compared to apolar solvents. In the same solvent, for instance, soman in hexane showed the lowest absorption wavelength value, 324.5 nm, and DCP the highest value, 330.8 nm. This behavior was observed in other tested solvents. The thermodynamic parameters indicate negative Gibbs free energy (ΔG) values for the O-ethyl-S-[2(diisopropylamino)ethyl] methylphosphonothioate with 1 reaction. On the other hand, the sarin and cyclosarin revealed the lowest Gibbs free energy (ΔG‡) values, being kinetically favorable and presenting more reactivity.
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  • 89
    Publication Date: 2020-04-21
    Description: Cola-nut leaf is an agricultural waste which was used in this research as biosorbent for the adsorption of Cd2+and Cr6+ from aqueous solutions. The leaves of cola nut were modified using 0.1 M HCl. Modified cola nut leaves biosorbent showed slightly higher percentage sorption than the unmodified leaves, for both heavy metals with increasing contact time, having greater affinity for Cd2+. The equilibrium sorption data was attained using the batch technique with increased pH (9) and increased adsorbent dose (1 g/25 cm3 of adsorbate) and initial metal concentration. The functional group of cola nut leaves before and after adsorption was determined using Fourier Transform Infrared Spectroscopy (FTIR). Kinetics data were best fitted to a pseudo-second-order model. Equilibrium data were better described by the Temkin isotherm model with a multilayer adsorption capacity. The study showed that leaves of cola nut are a promising biosorbent for Cd2+ and Cr6+ which could be utilized for industrial wastewater remediation.
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  • 90
    Publication Date: 2020-04-21
    Description: The present study aimed to develop diclofenac sodium nanoemulgel for managing pain and inflammation using the low-energy emulsification technique. Nanoemulsion of diclofenac was formulated using clove oil with adequate amount of surfactants and cosurfactants, and it was converted to hydrogel form using Carbopol 980 as the gelling agent. The droplet size of the oil globules in the nanoemulsion was found to be 64.07 ± 2.65 nm with a low polydispersity index (0.238 ± 0.02) along with high negative zeta potential (−39.06 mV). The developed nanoemulgel exhibited non-Newtonian and pseudoplastic behavior. The in vitro release profile of the developed nanoemulgel was higher as compared to marketed and conventional gel. The carrageenan-induced paw edema test was performed in rats to evaluate the anti-inflammatory activity of developed nanoemulgel. The developed nanoemulgel showed significantly higher (p
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  • 91
    Publication Date: 2020-04-21
    Description: Discovering the characteristics of the reaction kinetics of acid systems (hydrogen fluoride (HF), hydrochloric acid (HCl), and CH3COOH) at different concentrations with sodium bentonite can provide experimental support for optimising formulations used in removing plugs through acidification. By utilising a spectrophotometer and acid-base titration, changes in contents of Si, Al, and H+ concentration when sodium bentonite reacted with different acid systems (HF, HF, HCl, and HF and CH3COOH) at different concentrations (5%, 10%, and 15%) for different reaction times (1, 2, 4, 8, 12, and 24 h) at 45°C were measured. Based on this, a reaction kinetics model of H+ was fitted and reaction mechanisms of HF with sodium bentonite after adding HCl and CH3COOH were analysed. The results demonstrated that the rate of dissolution of Al was high and the reaction reached equilibrium in 1 h. Si showed a fast dissolution rate in the acid solution containing HF. In an HCl + HF + CH3COOH acid system, at a concentration of 15%, the greatest dissolution occurred, with a more stable dissolution rate and longer reaction time. Among the three acids tested, it was HF that mainly reacted with sodium bentonite, while the other two acids had weak reactions therewith. In the acid system containing HF, HF molecules reacted with sodium bentonite, rather than other forms, such as H+, F−, and HF2−. The addition of HCl could promote the reaction, while CH3COOH inhibited the reaction. The research results provide experimental support for optimising the formulation of such acid solutions.
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  • 92
    Publication Date: 2020-04-21
    Description: Natural organic fibers such as cotton, linen, and wool are readily attacked by microorganisms. Microbial growth on a textile fabric causes loss of strength and elongation, discoloration, and changes in appearance. The antibacterial finishing agents extracted from nettle plant leaf have been used to impart finish to the cotton fabric by using the Pad-Dry-Cure application method. The antibacterial activity of the finish was assessed quantitatively using the AATCC 100:2004 test method, and the antibacterial activity against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria was measured. There was a 100 to 99.75 percent reduction in the count of test bacteria. Physical properties of treated and untreated cotton fabrics such as absorbency, fabric stiffness, air permeability, and strength were analyzed. To evaluate the laundering effect of stinging nettle leaf finished fabric, samples were subjected to laundry with 5, 10, 15, 20, 25, 30, 35, and 40 washing cycles using standard AATCC test method 61, and bacterial count of treated samples was tested. The results showed gradual decrease in antibacterial property, with a 100 to 44% reduction in the bacterial count for Staphylococcus aureus and a 100 to 30% reduction in the bacterial count for Escherichia coli. The results of this investigation suggested that nettle leaf, a low-cost abundant plant in Ethiopia, can be used for antibacterial activity in woven cotton fabric.
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  • 93
    Publication Date: 2020-04-19
    Description: Considering the coexistence of cold chain agro-products and ordinary agro-products in the market, the research object is the cold chain logistics subsidy. It is designed that a supply chain system consisting of duopoly upstream agro-products suppliers and a downstream agro-products retailer for research. The mechanism of cold chain logistics subsidy is studied by analyzing the influence of cold chain subsidy on pricing behavior and cold chain decision-making of cold chain agro-products and ordinary agro-products. Based on the decentralized decision-making model without government subsidy, a differential pricing model for cold chain agro-products and ordinary agro-products with government subsidy is established in order to reduce the cost of cold chain agro-products. The optimal pricing strategy of two agro-products suppliers and their downstream retailer can be obtained by solving this problem. The research finds that differential pricing caused by government subsidy can achieve profit Pareto improvement of suppliers, retailer, and supply chain system of cold chain agro-products, but cannot achieve the optimal profit of the whole supply chain. Therefore, in view of the loss of supply chain efficiency caused by decentralized decision-making, the Shapley value method is used to make coordination, and the contract coordination mechanism is designed. Finally, the sensitivity of parameters is analyzed by a numerical example.
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  • 94
    Publication Date: 2020-04-10
    Description: The development of self-supporting high-efficiency catalysts is a major challenge for the efficient production of H2 via water splitting. In this manuscript, a freestanding Ni2P-Ni12P5/carbonized wood (CW) composite electrode was prepared by a simple hydrothermal method and high-temperature calcination using pine wood with uniform channel as support and a large number of hydroxyl groups as nucleation center. The morphology and structural characteristics indicated that the Ni2P and Ni12P5 nanoparticles were uniformly distributed within the hierarchical porous structure of the CW. In acid media, the as-prepared Ni2P-Ni12P5/CW exhibits an excellent catalytic activity with a low overpotential of 151 mV at 10 mA cm−2 and a reasonably good long-term stability.
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  • 95
    Publication Date: 2020-04-10
    Description: A series of (E)-3-(2-((5-(benzylideneamino)-1,3,4-thiadiazol-2-yl)thio) acetyl)-2H-chromen-2-one and its derivatives (4a-h) have been obtained using a one-pot multicomponent reaction with good yields. The compounds have been synthesized from 3-(2-bromoacetyl)chromen-2-ones (1), 5-amino-1,3,4-thiadiazole-2-thiol (2), and substituted benzaldehydes (3) in anhydrous ethanol and conc. H2SO4. Subsequently, all the synthesized compounds have been screened for their antimicrobial activity and characterized by analytical and spectral data.
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  • 96
    Publication Date: 2020-05-06
    Description: Clay minerals have large surface areas that contribute to their high adsorption capacity. Pure clays were often used. However, their prices remain expensive. However, the natural clay minerals that are locally available can have economic and environmental benefits for textile wastewater treatment. The tested natural clays had given low removal yields. Therefore, we wanted to test particular rich organic matter clay for adsorbing azo dye, which is a very toxic molecule. In order to make the use of this clay type have a better efficiency for removal of this dye from the polluted waters, the optimal conditions had been specified. The results indicated that advised conditions were as follows: 5 min was the contact time of dye-clay; the better adsorbent masses were 0.25 g and 0.5 g per 100 ml solution for raw (ANb) and purified clays (ANp), respectively; the initial dye concentrations were 1 gL−1 for raw clay and 50 mgL−1 for purified clay; pH solution had any effect on the yield of dye removal only when raw clay was used; however, acid environment was advised when purified clay was the adsorbent and for the two tested clays about 20–30°C was the better solution temperature. X-Ray diffraction, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM) analysis confirmed that functional groups of clay adsorbed the dye. Langmuir maximum adsorption capacities of ANb and ANp were found to be 397 mgg−1 and 132.3 mgg−1 at pH 7 and 5, respectively. Raw and chemically activated samples gave similar results. Adsorption of ANb and ANp data showed better agreement with the pseudo-second-order kinetic model. Thermodynamic parameters of the two adsorbents confirmed that the adsorption was endothermic (ΔH 〉 0) and spontaneous (ΔG0 
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  • 97
    Publication Date: 2020-05-05
    Description: Flesh fingered citron (FFC) essential oil (EO) is susceptible to volatilisation at room temperature. Therefore, its use as a nematicide requires a controlled release. In the present study, we encapsulated FFC EO in β-cyclodextrin by embedding and investigated release from the capsules compared to unembedded EO. We evaluated the structural and thermal properties of the capsules by SEM and TGA. The loading capacity was 32.67%, and the embedding yield was 96.24%, assuming that a core-to-wall quality ratio of 1 : 6 is optimal for the carrier. Using Caenorhabditis elegans as a model organism, we explored the toxicity of (1) FFC EO microcapsules (MCs) and (2) four key compounds of the EOs. The MCs enabled sustained release, e.g., 77% mortality after 4 h and 100% within an additional half-hour. The four main compounds in EO can each kill nematodes by reducing antioxidant activity. Since microencapsulation can improve FFC EO stability and prevent product loss due to adverse environments exposed to the air, encapsulating FFC EO in MCs has great potential as a new nematicide.
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  • 98
    Publication Date: 2020-05-07
    Description: Based on the TIMES model, a system for CO2 emission reduction in China’s power industry is built in this paper. Four scenarios including different carbon tax levels are set up, simulating the CO2 emissions of China’s power industry in 2020–2050 by using scenario analysis method. The power consumption demand, primary energy consumption structure, CO2 emission characteristics, emission reduction potential, and cost of different carbon tax levels are quantitatively studied. In combination with the impact on China’s macroeconomy, the carbon tax level corresponding to the best CO2 emission reduction effect of China’s power industry is obtained, aiming to provide key data and a theoretical basis for China’s low-carbon development as well as the optimization and adjustment of global power production system. The results show that with the development of economy and society in the future, China’s power consumption demand will increase year by year, while the primary energy consumption of the power industry will maintain a rapid growth. The power industry still relies heavily on fossil energy, which will cause great pressure on China’s economic development and ecological environment. Carbon tax will have an important impact on the primary energy supply structure of China’s power industry, and renewable energy can be developed in different degrees. CO2 emissions will be significantly reduced, reaching the peak value during 2030–2040 in China’s power industry. The medium carbon tax level (TAX-2) set in this paper can meet the requirements of both CO2 emission reduction effect and cost in the power industry, with the most elastic impact on the national economy and the smallest GDP loss, which can be used as an effective environmental economic policy tool.
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  • 99
    Publication Date: 2020-05-08
    Description: The present study has been undertaken to analyze the total accumulated burden of volatile organic compounds (VOCs) in blood of occupationally exposed workers. The headspace technique combined with gas chromatography with flame ionization detector was used for the quantitative analysis of the different volatile organic compounds (isopropyl alcohol, phenol, benzene, dichloromethane, ethanol, ethyl acetate, and toluene) in 80 blood samples from the workers belonging to different occupations i.e., shoe polish workers, thinner handlers, paint workers, furniture polish workers, petrol station attendants, textile dyeing workers, printing press workers, and dry port workers as biomonitoring is one of the most promising methods for analyzing the individual burden of VOCs. Another purpose of this study was to investigate the correlation between detected concentrations of VOCs and associated health issues reported by the workers of these professions. Results of the study revealed the presence of different VOCs in blood samples of approximately 70 workers out of 80, and statistical analysis proved a strong relationship between the reported work experience, working hours, and diseases and the detected concentrations of respective volatile organic compounds.
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  • 100
    Publication Date: 2020-05-13
    Description: In this study, the de-NOx performance of Cu-based zeolite catalysts supported on topological structure (SSZ-13, BEA, ZSM-5) and loaded with different doses of copper (from 2 to 6 wt.%) was investigated. The preparation of copper-based catalysts adopted the incipient wetness impregnation method. To analyze the physicochemical properties of the catalysts, advanced techniques like BET, XRD, NH3-TPD, H2-TPR, and DRS UV-Vis were used. The performance tests suggested the 4Cu/SSZ-13 catalyst exhibited higher low-temperature activity and wider temperature window. Furthermore, compared with Mn-Cu/SSZ-13, the Ce-Cu/SSZ-13 catalysts exhibited better de-NOx performance.
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