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  • Articles  (251)
  • Hindawi  (251)
  • 2010-2014  (251)
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  • International Journal of Spectroscopy  (116)
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  • Chemistry and Pharmacology  (251)
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  • 1
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    A Simulation Study of the Far-Infrared Absorption Spectra of HCl Diluted in Liquid Ar (2013)
    Hindawi
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    Publication Date: 2013-09-25
    Description: The far-infrared absorption coefficient of HCl diluted in liquid Ar has been calculated by using a mixed classical-quantum stochastic simulation approach. The simulated spectra have been compared with the available experimental data at different thermodynamic conditions without using ad hoc fitting parameters. Despite the fact that some discrepancies can be observed in the high frequency side of the far-infrared bands, a reasonable agreement has been found between the theoretical and the experimental spectral profiles. Both, classical and quantum simulated line shapes were comparatively analyzed, determining the time scales involved in the rotational spectra.
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  • 2
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    Smoothed Linear Modeling for Smooth Spectral Data (2013)
    Hindawi
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    Publication Date: 2013-06-07
    Description: Classification and prediction problems using spectral data lead to high-dimensional data sets. Spectral data are, however, different from most other high-dimensional data sets in that information usually varies smoothly with wavelength, suggesting that fitted models should also vary smoothly with wavelength. Functional data analysis, widely used in the analysis of spectral data, meets this objective by changing perspective from the raw spectra to approximations using smooth basis functions. This paper explores linear regression and linear discriminant analysis fitted directly to the spectral data, imposing penalties on the values and roughness of the fitted coefficients, and shows by example that this can lead to better fits than existing standard methodologies.
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  • 3
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    Crystal Defects and Cation Redistribution Study on Nanocrystalline Cobalt-Ferri-Chromites by Positron Annihilation Spectroscopy (2013)
    Hindawi
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    Publication Date: 2013-06-12
    Description: Positron lifetime and Doppler broadening measurements were carried out on nanocrystalline (grain size ~60–65 nm) samples of the Cr3+-substituted cobalt ferrite system with general chemical formula CoCrxFe2−xO4 (−2.0) synthesized by the coprecipitation technique. The results indicated selective trapping of positrons in large vacancy clusters initially at the tetrahedral (A-) sites and then with Cr3+-substitution up to concentration , at the octahedral (B-) sites. The results are consistent with the cation distribution determined from X-ray diffraction line intensity calculations, which indicated partial inversion of the inverse spinel ferrite, subsequent stabilization over a range of substitution ( to 1.7), and finally the full inversion to the normal spinel chromite (CoCr2O4, ). In the intermediate range of substitution, lattice contraction prevented a fraction of Co2+ ions released from the (B-) sites from entering the tetrahedral sites, and these vacancies at the (A-) sites trapped positrons. Although the samples were composed of nanocrystalline grains, only an insignificant fraction of positrons were diffused and annihilated at the grain surfaces, since the grain sizes and the thermal diffusion length of positrons nearly overlapped.
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  • 4
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    Study of the Halogen Bonding between Pyridine and Perfluoroalkyl Iodide in Solution Phase Using the Combination of FTIR and 19F NMR (2013)
    Hindawi
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    Publication Date: 2013-06-12
    Description: Halogen bonding between pyridine and heptafluoro-2-iodopropane (iso-C3F7I)/heptafluoro-1-iodopropane (1-C3F7I) was studied using a combination of FTIR and 19F NMR. The ring breathing vibration of pyridine underwent a blue shift upon the formation of halogen bonds with both iso-C3F7I and 1-C3F7I. The magnitudes of the shifts and the equilibrium constants for the halogen-bonded complex formation were found to depend not only on the structure of the halocarbon, but also on the solvent. The halogen bond also affected the Cα-F (C-F bond on the center carbon) bending and stretching vibrations in iso-C3F7I. These spectroscopic effects show some solvent dependence, but more importantly, they suggest the possibility of intermolecular halogen bonding among iso-C3F7I molecules. The systems were also examined by 19F NMR in various solvents (cyclohexane, hexane, chloroform, acetone, and acetonitrile). NMR dilution experiments support the existence of the intermolecular self-halogen bonding in both iso-C3F7I and 1-C3F7I. The binding constants for the pyridine/perfluoroalkyl iodide halogen bonding complexes formed in various solvents were obtained through NMR titration experiments. Quantum chemical calculations were used to support the FTIR and 19F NMR observations.
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  • 5
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    Resolution of Ternary Mixture of Aspirin, Atorvastatin, and Clopidogrel by Chemometric-Assisted UV Spectroscopic and Liquid Chromatography Methods (2013)
    Hindawi
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    Publication Date: 2013-09-23
    Description: Two chemometrics-assisted UV spectrophotometric methods were proposed for the resolution of ternary mixtures without any chemical pretreatment. The first method is based on modification of H-point standard addition method which permits simultaneous analysis of three species from a unique calibration set by making the simultaneous addition of the three analytes. Quotient between the spectra of aspirin, atorvastatin, and clopidogrel was obtained and the results showed that simultaneous determination of aspirin, atorvastatin, and clopidogrel can be obeyed in the linear range 2.5–20 μg mL−1 of aspirin, 2.5–17.5 μg mL−1 of atorvastatin, and 2.5–20 μg mL−1 of clopidogrel in ternary mixture. The second method is based on the combination of the first derivative spectra and Cramer's matrix rule. In the matrix calculation, clopidogrel has zero crossing point at 316.8 and 212 nm, while for atorvastatin the zero crossing point at 250 nm where the matrix is greatly simplified and easily solved. The linear concentration ranges were 2.5–20 μg mL−1 aspirin, 2.5–17.5 μg mL−1 atorvastatin and 2.5–20 μg mL−1 clopidogrel in ternary mixtures. The results proved that the simultaneous determination of aspirin, atorvastatin, and clopidogrel could be obeyed. Both methods were applied for capsules containing the three ingredients and results were in good concordance with alternative liquid chromatography.
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  • 6
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    Raman Spectroscopy at High Pressures (2013)
    Hindawi
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    Publication Date: 2013-01-02
    Description: Raman spectroscopy is one of the most informative probes for studies of material properties under extreme conditions of high pressure. The Raman techniques have become more versatile over the last decades as a new generation of optical filters and multichannel detectors become available. Here, recent progress in the Raman techniques for high-pressure research and its applications in numerous scientific disciplines including physics and chemistry of materials under extremes, earth and planetary science, new materials synthesis, and high-pressure metrology will be discussed.
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  • 7
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    A Simulation Study of the Fundamental Vibrational Shifts of HCl Diluted in Ar, Kr, and Xe: Anharmonic Corrections Effects (2012)
    Hindawi
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    Publication Date: 2012-10-04
    Description: We have calculated the vibrational solvent shifts of the fundamental bands of HCl diluted in Ar, Kr, and Xe solutions at different thermodynamic conditions by means of the molecular dynamics technique and a model for the isotropic part of the interaction depending on the vibration. The theoretical vibrational shifts, which were compared with the available experimental data, have been determined by considering both, the usual linear Buckingham terms and the nonlinear anharmonic corrections, and the latter omitted in a previous work for the HCl in Ar and Kr. We have found that the Buckingham contributions dominate the solvent shifts of the fundamental bands of HCl in Ar, Kr, and Xe, although the anharmonic shifts’ present significant greater values than those obtained previously for N2 diluted in liquid Ar and pure liquid N2, both at normal conditions. We have analyzed the solvent shifts influence of the linear and quadratic (in the vibrational coordinate) oscillator-bath interaction terms and also the Dunham intramolecular potential effects on the anharmonic contributions.
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  • 8
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    Integrated Band Intensities of Ethylene (12 (2012)
    Hindawi
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    Publication Date: 2012-08-29
    Description: The integrated band intensities of ethylene (12C2H4) in the 640–3260 cm−1 region were determined by Fourier transform infrared (FTIR) spectroscopy. The infrared absorbance spectra of the
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  • 9
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    Molecular Laser Spectroscopy as a Tool for Gas Analysis Applications (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: We have used the traceable infrared laser spectrometric amount fraction measurement (TILSAM) method to perform absolute concentration measurements of molecular species using three laser spectroscopic techniques. We report results performed by tunable diode laser absorption spectroscopy (TDLAS), quantum cascade laser absorption spectroscopy (QCLAS), and cavity ring down spectroscopy (CRDS), all based on the TILSAM methodology. The measured results of the different spectroscopic techniques are in agreement with respective gravimetric values, showing that the TILSAM method is feasible with all different techniques. We emphasize the data quality objectives given by traceability issues and uncertainty analyses.
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  • 10
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    Protein Interactions Investigated by the Raman Spectroscopy for Biosensor Applications (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: Interaction and surface binding characteristics of staphylococcal protein A (SpA) and an anti-Escherichia coli immunoglobulin G (IgG) were studied using the Raman spectroscopy. The tyrosine amino acid residues present in the α-helix structure of SpA were found to be involved in interaction with IgG. In bulk interaction condition the native structure of proteins was almost preserved where interaction-related changes were observed in the overall secondary structure (α-helix) of SpA. In the adsorbed state, the protein structure was largely modified, which allowed the identification of tyrosine amino acids involved in SpA and IgG interaction. This study constitutes a direct Raman spectroscopic investigation of SpA and IgG (receptor-antibody) interaction mechanism in the goal of a future biosensor application for detection of pathogenic microorganisms.
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  • 11
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    Raman Microimaging Using a Novel Multifiber-Based Device: A Feasibility Study on Pharmaceutical Tablets (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: Raman microimaging is a potential analytical technique in health field and presents many possible pharmaceutical applications. In this study, we tested a micrometer spatial resolution probe coupled to a portable Raman imager via an indexed multifiber bundle. At the level of the probe, the fibers were arranged in a circular geometry in order to fit to the pupil of an objective. The imaging potential of this Raman system was assessed on pharmaceutical-like pellets. We showed that this setup permits to record, nearly in real time, Raman images with a micrometer resolution. The collected images revealed a marked heterogeneity in chemicals distribution. Further investigations will be led on cells and biological tissues to evaluate the potential of this Raman imaging device for biomedical applications.
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  • 12
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    Study on the Interaction of Bovine Serum Albumin with Ceftriaxone and the Inhibition Effect of Zinc (II) (2012)
    Hindawi
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    Publication Date: 2012-07-16
    Description: The mechanism of the interaction between bovine serum albumin (BSA) and ceftriaxone with and without zinc (II) (Zn2+) was studied employing fluorescence, ultraviolet (UV) absorption, circular dichroism (CD), and synchronous fluorescence spectral methods. The intrinsic fluorescence of BSA was quenched by ceftriaxone in a static quenching mode, which was authenticated by Stern-Volmer calculations. The binding constant, the number of binding sites, and the thermodynamic parameters were obtained, which indicated a spontaneous and hydrophobic interaction between BSA and ceftriaxone regardless of Zn2+. Changes in UV absorption, CD, and synchronous fluorescence spectral data are due to the microenvironment of amide moieties in BSA molecules. In the BSA-ceftriaxone-Zn2+ system, Zn2+ must first interact with ceftriaxone forming a complex, which inhibits BSA binding to ceftriaxone. The present work uses spectroscopy to elucidate the mechanism behind the interaction between BSA and ceftriaxone in the presence and absence of Zn2+. The BSA and ceftriaxone complex provides a model for studying drug-protein interactions and thus may further facilitate the study of drug metabolism and transportation.
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  • 13
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    Design Considerations for a Portable Raman Probe Spectrometer for Field Forensics (2012)
    Hindawi
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    Publication Date: 2012-09-14
    Description: Raman spectroscopy has been shown to be a viable method for explosives detection. Currently most forensic Raman systems are either large, powerful instruments for laboratory experiments or handheld instruments for in situ point detection. We have chosen to examine the performance of certain benchtop Raman probe systems with the goal of developing an inexpensive, portable system that could be used to operate in a field forensics laboratory to examine explosives-related residues or samples. To this end, a rugged, low distortion line imaging dispersive Raman spectrograph was configured to work at 830 nm laser excitation and was used to determine whether the composition of thin films of plastic explosives or small (e.g., ≤10 μm) particles of RDX or other explosives or oxidizers can be detected, identified, and quantified in the field. With 300 mW excitation energy, concentrations of RDX and PETN can be detected and reconstructed in the case of thin Semtex smears, but further work is needed to push detection limits of areal dosages to the ~1 μg/cm2 level. We describe the performance of several probe/spectrograph combinations and show preliminary data for particle detection, calibration and detection linearity for mixed compounds, and so forth.
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  • 14
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    Vital Autofluorescence: Application to the Study of Plant Living Cells (2012)
    Hindawi
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    Publication Date: 2012-09-11
    Description: The application of various microscopy methods such as luminescence microscopy, microspectrofluorimetry and laser-scanning confocal microscopy has been considered as an approach to study the autofluorescence of plant living cells—from cell diagnostics up to modelling the cell-cell contacts and cell interactions with fluorescent biologically active substances. It bases on the direct observations of secretions released from allelopathic and medicinal species and the cell-donor interactions with cell-acceptors as biosensors (unicellular plant generative and vegetative microspores). Special attention was paid to the interactions with pigmented and fluorescing components of the secretions released by the cells-donors from plant species. Colored components of secretions are considered as histochemical dyes for the analysis of cellular mechanisms at the cell-cell contacts and modelling of cell-cell interactions. The fluorescence of plant biosensors was also recommended for the testing of natural plant excretions as medical drugs.
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  • 15
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    Vibrational Spectrum of HMX at CO2 Laser Wavelengths: A Combined DRIFT and LPAS Study (2012)
    Hindawi
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    Publication Date: 2012-09-17
    Description: The vibrational spectrum of solid standard HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) was investigated. Two spectroscopic techniques were adopted for their different sensitivity and resolution. A preliminary survey of the absorption bands of the compound was performed in the 8000–400 cm−1 spectral range by employing the diffuse reflectance infrared Fourier transform (DRIFT) technique at room temperature. The high-resolution line spectrum of HMX was obtained in the 9.2–10.8 μm spectral range by laser photoacoustic spectroscopy (LPAS) method, using a line tuneable 10 W stabilised cw CO2 laser light source. By comparing the data collected with the two techniques in the common frequency range, a very good agreement was observed.
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  • 16
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    Effects of Molecular Structure on Intramolecular Charge Carrier Transport in Dithieno [3,2-b: 2′,3′-d] Pyrrole-Based Conjugated Copolymers (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: Intramolecular mobility of positive charge carriers in conjugated polymer films based on dithieno [2,3-b: 2′,3′-d] pyrrole (DTP) is studied by time-resolved microwave conductivity (TRMC). A series of DTP homopolymer and copolymers combined with phenyl, 2,2′-biphenyl, thiophene, 2,2′-bithiophene, and 9,9′-dioctylfluorene were synthesized by Suzuki-Miyaura and Yamamoto coupling reactions. Polymers containing DTP unit are reported to show high value of hole mobility measured by FET method, and this type of polymers is expected to have stable HOMO orbitals which are important for hole transportation. Among these copolymers, DTP coupled with 9,9′-dioctylfluorene copolymer showed the highest charge carrier mobility as high as 1.7 cm2/Vs, demonstrating an excellent electrical property on rigid copolymer backbones.
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  • 17
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    The Effect of Multidentate Biopolymer Based on Polyacrylamide Grafted onto Kappa-Carrageenan on the Spectrofluorometric Properties of Water-Soluble CdS Quantum Dots (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: A new fluorescent composite based on CdS quantum dots immobilized on the multidentate biopolymer matrix is prepared through the graft copolymerization of the acrylamide onto kappa-Carrageenan. A variety of techniques like thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR) was used to confirm the structure of the obtained samples. To investigate the spectrofluorometric properties, fluorescence spectroscopy of the obtained quantum dots was studied.
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  • 18
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    Gas Chromatography Electron Ionization Mass Spectral Analysis of Thio Analogues of Pyrimidine Bases: 5-Bromo-2,4-di-o-(m- and p-) chloro- (bromo-)benzylthiouracils and 6-methyluracils (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: Electron ionization (EI) mass spectral fragmentation routes of twelve 5-bromo-2,4-di-o-(m- and p-) chloro- (bromo-)benzyl-thiouracils and 6-methyluracils are investigated. The compounds studied are analyzed using gas chromatography/mass spectrometry (GC/MS). Fragmentation pathways, whose elucidation is assisted by accurate mass measurements and metastable transitions, are discussed. Correlation between the abundances of the selected fragment ions of the compounds investigated is discussed. The data obtained make grounds for distinction of structural isomers.
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  • 19
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    Identification of Halohydrins as Potential Disinfection By-Products in Treated Drinking Water (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: In 2001, two potential disinfection by-products (DBPs) were tentatively identified as 1-aminoxy-1-chlorobutan-2-ol (DBP-A) and its bromo analogue (DBP-B) (Taguchi 2001). Subsequently it became clear, by consulting an updated version of the NIST database, that their mass spectra are close to those of the halohydrins 4-chloro-2-methylbutan-2-ol and 3-bromo-2-methylbutan-2-ol. To establish the structures of these DBPs, additional mass spectrometric experiments, including Fourier transform ion cyclotron resonance (FTICR), were performed on treated drinking water samples and authentic halohydrin standards. It appears that DBP-A is 3-chloro-2-methylbutan-2-ol and that DBP-B is its bromo analogue. DBP-B has been detected in ozonated waters containing bromide. Our study also shows that these DBPs can be laboratory artefacts, generated by the reaction of residual chlorine in the sample with 2-methyl-2-butene, the stabilizer in the CH2Cl2 used for extraction. This was shown by experiments using CH2Cl2 stabilized with deuterium labelled 2-methyl-2-butene. Quenching any residual chlorine in the drinking water sample with sodium thiosulfate minimizes the formation of these artefacts.
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  • 20
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    Old and New Flavors of Flame (Furnace) Atomic Absorption Spectrometry (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: This paper presents some recent applications of Flame Atomic Absorption Spectrometry (FAAS) to different matrices and samples. The time window selected was from 2006 up to March, 2011, and several aspects related to food, biological fluids, environmental, and technological samples analyses were reported and discussed. In addition, the chemometrics application for FAAS methods development was also taken into account, as well as the use of metal tube atomizers in air/acetylene flame. Preconcentration methods coupled to FAAS were discussed, and several approaches related to speciation, flotation, ionic liquids, among others were discussed. This paper can be interesting for researchers and FAAS users in order to see the state of the art of this technique.
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  • 21
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    Fragmentation Pathways of Trifluoroacetyl Derivatives of Methamphetamine, Amphetamine, and Methylenedioxyphenylalkylamine Designer Drugs by Gas Chromatography/Mass Spectrometry (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: Methamphetamine (MA), amphetamine (AM), and the methylenedioxyphenylalkylamine designer drugs, such as 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyethylamphetamine (MDEA), N-methyl-1-(3,4-methylenedioxyphenyl)-2-butanamine (MBDB), 3,4-methylenedioxyamphetamine (MDA), and 3,4-(methylenedioxyphenyl)-2-butanamine (BDB), are widely abused as psychedelics. In this paper, these compounds were derivatized with trifluoroacetic (TFA) anhydride and analyzed by gas chromatography/mass spectrometry using electron ionization in positive mode. Gas chromatographic separation for TFA derivatives of all compounds was successfully resolved using an Equity-5 fused silica capillary column with a poly (5% diphenyl-95% dimethylsiloxane) stationary phase. Base peaks or prominent peaks of MA, AM, MDMA, MDEA, MBDB, MDA, and BDB appeared at m/z 154, 140, 154, 168, 168, 135, and 135, respectively. These occurred due to α-cleavage from the amide nitrogen, splitting into the TFA imine species and benzyl or methylenedioxybenzyl cations. Further prominent fragment ions at m/z 118 for MA and AM, m/z 162 for MDMA, MDEA, and MDA, and m/z 176 for MBDB and BDB were produced by cleavage of the phenylpropane or methylenedioxypropane hydrocarbon radical cation via a hydrogen rearrangement. These fragmentation pathways for the TFA derivatives of all the compounds are summarized and illustrated in this paper.
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  • 22
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    QCLAS and CRDS-Based CO Quantification as Aimed at in Breath Measurements (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: Laser-spectrometric methods to derive absolute and traceable carbon monoxide (CO) amount fractions in exhaled human breath could be of advantage for early disease detection as well as for treatment monitoring. As proof-of-principle laboratory experiment, we employed intra-pulse and continuous wave (cw) quantum cascade laser spectroscopy (QCLAS), both at 4.6 μm. Additional experiments were carried out applying cw cavity ring-down spectroscopy (CRDS) with a CO sideband laser and a QCL. We emphasize metrological data quality objectives, thatis, traceability and uncertainty, which could serve as essential benefits to exhaled breath measurements. The results were evaluated and compared on a 100 μmol/mol CO level using the two QCLAS spectrometers, and the cw CO sideband laser CRDS setup. The relative standard uncertainties of the pulsed and the cw QCLAS CO amount fraction results were ±4.8 and ±2.8%, respectively, that from the CO sideband laser CRDS was ±2.7%. Sensitivities down to a 3 nmol/mol CO level were finally demonstrated and quantified by means of cw CRDS equipped with a QCL yielding standard uncertainties of about ±2.5 that are exclusively limited by the available line strength figure quality. With this study we demonstrate the achieved comparability of CO quantifications, adhering metrological principles.
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  • 23
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    Strain Effects on Optical Properties of (In,Ga)As-Capped InAs Quantum Dots Grown by Molecular Beam Epitaxy on GaAs (113)A Substrate (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: We have investigated the optical properties of InAs/GaAs (113)A quantum dots grown by molecular beam epitaxy (MBE) capped by (In,Ga)As. Reflection high-energy electron diffraction (RHEED) is used to investigate the formation process of InAs quantum dots (QDs). A broadening of the PL emission due to size distribution of the dots, when InAs dots are capped by GaAs, was observed. A separation between large and small quantum dots, when they are encapsulated by InGaAs, was shown due to hydrostatic and biaxial strain action on large and small dots grown under specifically growth conditions. The PL polarization measurements have shown that the small dots require an elongated form, but the large dots present a quasi-isotropic behavior.
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  • 24
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    Isotope Shifts in High Lying Levels of Dy I and Er I by High-Resolution UV Laser Spectroscopy (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: High-resolution atomic-beam ultraviolet (UV) laser spectroscopy in Dy I and Er I has been performed. Isotope shifts have been measured for two transitions in Dy I and one transition in Er I. Specific mass shifts and field shifts have been derived for the studied transitions, and large differences between the two 4f106s2–4f106s6p transitions in Dy I have been found. From the derived specific mass shifts and field shifts, configuration mixing at the upper levels of transitions has been discussed.
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    Near-Infrared Spectroscopy of the Bladder: New Parameters for Evaluating Voiding Dysfunction (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: We describe innovative methodology for monitoring alterations in bladder oxygenation and haemodynamics in humans using near-infrared spectroscopy (NIRS). Concentrations of the chromophores oxygenated (O2Hb) and deoxygenated (HHb) haemoglobin and their sum (total haemoglobin) differ during bladder contraction in health and disease. A wireless device that incorporates three paired light emitting diodes (wavelengths 760 and 850 nanometers) and silicon photodiode detector collects data transcutaneously (10 Hz) with the emitter/detector over the bladder during spontaneous bladder emptying. Data analysis indicates comparable patterns of change in chromophore concentration in healthy children and adults (positive trend during voiding, predominantly due to elevated O2Hb), but different changes in symptomatic subjects with characteristic chromophore patterns identified for voiding dysfunction due to specific pathophysiologies: bladder outlet obstruction (males), overactive bladder (females), and nonneurogenic dysfunction (children). Comparison with NIRS muscle data suggests altered bladder haemodynamics and/or oxygenation may underlie voiding dysfunction offering new insight into the causal physiology.
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    Electronic Absorption Spectra of Some Triazolopyrimidine Derivatives (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: The electronic absorption spectra of triazolo pyrimidine and some of its derivatives were measured in polar as well as nonpolar solvents. Assignment of the observed transitions is facilitated via molecular orbital calculations. Charge density distributions, dipole moments, and the extent of delocalization of the MOS were used to interpret the observed solvent effects. The observed transitions are assigned as charge transfer (CT), localized, and delocalized according to the contribution of the various configurations in the CI-states. The correspondence between the calculated and experimental transition energies is satisfactory.
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    Nickel(II) Selective PVC-Based Membrane Sensor Using a Schiff Base (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: A polyvinylchloride (PVC) membrane optode was prepared by using 1,2-di(o-salicylaldiminophenylthio)ethane (H2DSALPTE) as a chelating reagent for selective determination of Ni(II) ions. The optimized membranes incorporating H2DSALPTE as an ionophore, sodium tetraphenylborate (NaTPB) as an anion excluder, and tributyl phosphate (TBP) as a solvent mediator were prepared and applied for determination of Ni(II) ions. The membrane responded to Ni(II) ion by changing the color from yellow to green in an acetate buffer solution at pH 6.0. The best performance was observed when the membrane having a composition of 3.17% ligand, 31.64% PVC, 63.29% TBP, and 1.90% NaTPB. The membrane can be worked well over a wide concentration range from 1.0 × 10−5 to 5.0 × 10−3 M. The membrane exhibited a detection limit of 8.51 × 10−6 M, and the response time of the membrane was within 7–12 min depending on the concentration of Ni(II) ions. The selectivity of the probe towards nickel determination was found to be very good. Experimental results showed that the probe could be used as an effective tool in analyzing the Ni(II) content of water samples.
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    Recent Applications of Ion Mobility Spectrometry in Diagnosis of Vaginal Infections (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: Vaginal infections (vaginosis) globally affect more than 15% of the female population of reproductive age. However, diagnosis of vaginosis and differentiating between the three common types: bacterial vaginosis (BV), vulvovaginal candidiasis (VVC), and trichomoniasis are challenging. Elevated levels of the biogenic amines, trimethylamine (TMA), putrescine, and cadaverine have been found in vaginal discharge fluid of women with vaginosis. Ion mobility spectrometry (IMS) is particularly suitable for measurement of amines even in complex biological matrices due to their high proton affinity and has been shown to be suitable for the diagnosis of vaginal infections. Recent developments that have increased the accuracy of the technique for diagnosis of BV and simplified sample introduction are described here.
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    Spectrophotometric Quantification of Toxicologically Relevant Concentrations of Chromium(VI) in Cosmetic Pigments and Eyeshadow Using Synthetic Lachrymal Fluid Extraction (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: Chromium(VI) salts are possible contaminants of the chromium(III) pigments used as colorants in eyeshadow preparations. The use of products containing these contaminants poses acute risks for sensitization and contact allergies. Chromium(VI) compounds are also classified as carcinogenic to humans (IARC group 1). An analytical method to analyse trace levels of chromium(VI) in eyeshadow was developed in this study. The method is based on an extraction of the chromium(VI) from the sample using a maximum extraction with alkali and additionally with synthetic lachrymal fluid to simulate physiological conditions. Following derivatization with 1,5-diphenylcarbazide, the extracted chromium(VI) is then quantified by spectrophotometry (540 nm). Validation tests indicated a method standard deviation (inter- and intraday) of 8.7% and a linear range up to 25 mg/kg. The average recovery was 107.9%, and the detection limit was 2.7 mg/kg. The applicability of the procedure was confirmed by the analysis of pigments and authentic eyeshadow matrices.
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    Unilateral NMR: A Noninvasive Tool for Monitoring In Situ the Effectiveness of Intervention to Reduce the Capillary Raise of Water in an Ancient Deteriorated Wall Painting (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: Portable unilateral NMR was used to quantitatively map in a fully noninvasive way the moisture distribution in an ancient deteriorated wall painting before and after an intervention to reduce the capillary raise of water through the wall. Maps obtained at a depth of 0.5 cm clearly showed the path of the capillary raise and indicated that, after the intervention, the moisture level was reduced. Maps obtained by measuring the first layers of the wall painting were affected by the critical environmental conditions of the second hypogeous level of St. Clement Basilica, Rome, and by the presence of salts efflorescence and encrustations on the surface of the wall painting. The morphology and the elemental composition of salts investigated by SEM-EDS indicated that efflorescences and encrustations were mostly constituted of gypsum and calcite. The presence of these salts is explained with the presence of high concentration of carbon dioxide and sulphur-rich particles due to pollution which, along with the high-moisture level and the extremely feeble air circulation, cause recarbonation and sulphation processes on the plaster surface.
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    Spectroscopic Studies of Distorted Structure Systems in the Vibron Model: Application to Porphyrin and Its Isotopomers (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: We have introduced an algebraic technique to biomolecules (porphyrins) family to determine the vibrational spectra. We present an algebraic model of vibrations of polyatomic biomolecules, as an example, the vibrational analysis of stretching modes of nickel octaetheylporphyrin (Ni(OEP)) and its isotopomers. The algebraic technique obtained the results are compared with experimental data; the results are showing good accuracy. Some reassignments of energy levels that predict location of energy states not yet observed.
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    Rapid Determination of Total Thujone in Absinthe Using 1H NMR Spectroscopy (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: 1H NMR spectroscopy is utilized to quantify total thujone (sum of α- and β-isomers) in absinthe. For sample preparation, a simple dilution with buffer is required. Thujone produces a distinct peak of the CH2 group in the cyclopentanone moiety in the 2.13–2.11 ppm range. No overlap with other typical constituents such as anethole or fenchone occurs. The detection limit of 0.3 mg/L is adequate to control the EU maximum limit. The relative standard deviation was 6%, and linearity was observed from 1 to 100 mg/L. Applicability was proven by analysis of 69 authentic absinthes. The correlation between NMR and our previous method consisting of liquid-liquid extraction followed by GC/MS was significant (P<0.0001,R=0.93). The simple and cheap NMR method can be used for rapid screening of absinthes for total thujone content while chromatographic techniques are recommended for more specific (α- and β-thujone isomers) analysis if required.
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    Fast Determination of Manganese in Milk and Similar Infant Food Samples Using Multivariate Optimization and GF AAS (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: Manganese is an essential element, but high levels in foods can be toxic mainly for children. A fast and efficient method to determine Mn in milk and other infant foods using slurries and liquid samples is presented. Slurries were prepared in ultrapure water with 10 minutes of sonication. Liquid samples were diluted in ultrapure water when necessary. Multivariate optimization was used to establish some optimal analytical parameters through a fractional factorial design and a central composite design. Slurred and diluted samples were analyzed directly by GF AAS. The method presented limit of detection of (0.98±0.04) μg L−1, characteristic mass of (2.9±0.3) pg (recommended value 2 pg), RSD of 2.3% (n=5), and linear range from 0.98 to 20.0 μg L−1 using iridium as permanent modifier. The accuracy was evaluated analyzing two certified reference materials: nonfat milk powder (SRM1549) and whole milk powder (SRM8435). The powdered samples concentrations were between 0.210 and 26.3 μg g−1.
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    Demonstrated Wavelength Portability of Raman Reference Data for Explosives and Chemical Detection (2012)
    Hindawi
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    Publication Date: 2012-07-06
    Description: As Raman spectroscopy continues to evolve, questions arise as to the portability of Raman data: dispersive versus Fourier transform, wavelength calibration, intensity calibration, and in particular the frequency of the excitation laser. While concerns about fluorescence arise in the visible or ultraviolet, most modern (portable) systems use near-infrared excitation lasers, and many of these are relatively close in wavelength. We have investigated the possibility of porting reference data sets from one NIR wavelength system to another: We have constructed a reference library consisting of 145 spectra, including 20 explosives, as well as sundry other compounds and materials using a 1064 nm spectrometer. These data were used as a reference library to evaluate the same 145 compounds whose experimental spectra were recorded using a second 785 nm spectrometer. In 128 cases of 145 (or 88.3% including 20/20 for the explosives), the compounds were correctly identified with a mean “hit score” of 954 of 1000. Adding in criteria for when to declare a correct match versus when to declare uncertainty, the approach was able to correctly categorize 134 out of 145 spectra, giving a 92.4% accuracy. For the few that were incorrectly identified, either the matched spectra were spectroscopically similar to the target or the 785 nm signal was degraded due to fluorescence. The results indicate that imported data recorded at a different NIR wavelength can be successfully used as reference libraries, but key issues must be addressed: the reference data must be of equal or higher resolution than the resolution of the current sensor, the systems require rigorous wavelength calibration, and wavelength-dependent intensity response should be accounted for in the different systems.
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    New Possibility for REE Determination in Oil (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: A novel approach of rare earth elements (REE) determination in crude oil is suggested. Special application of countercurrent chromatography (CCC) is used as a sample pretreatment tool. An oil sample is continuously pumped through the rotating coil column (RCC) as a mobile phase, while an aqueous phase (nitric acid solution) is retained as a stationary phase. Two phases are kept well mixed and agitated, but there is no emulsion at the interface under the chosen conditions. Special features of CCC give an opportunity to vary the volume of oil samples to be analyzed from 10 mL to 1 L or more. Trace metals are preconcentrated into 10 mL of stationary phase (acidic solutions) pumped out of the column so that analysis can be easily determined with inductively coupled plasma mass spectrometry (ICP-MS) without additional sample preparation procedures. Optimal concentration of nitric acid in the stationary phase for preconcentration of REE from oil by CCC has been investigated. The combination of CCC with ICP-MS gives the possibility to develop a rapid, reliable, and accurate method of trace metal including rare earth elements (REE) determination in crude oils and oil products. Such method could be an alternative for unexpanded and expensive neutron-activation analysis (NAA).
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    Raman Spectroscopy for Homeland Security Applications (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: Raman spectroscopy is an analytical technique with vast applications in the homeland security and defense arenas. The Raman effect is defined by the inelastic interaction of the incident laser with the analyte molecule’s vibrational modes, which can be exploited to detect and identify chemicals in various environments and for the detection of hazards in the field, at checkpoints, or in a forensic laboratory with no contact with the substance. A major source of error that overwhelms the Raman signal is fluorescence caused by the background and the sample matrix. Novel methods are being developed to enhance the Raman signal’s sensitivity and to reduce the effects of fluorescence by altering how the hazard material interacts with its environment and the incident laser. Basic Raman techniques applicable to homeland security applications include conventional (off-resonance) Raman spectroscopy, surface-enhanced Raman spectroscopy (SERS), resonance Raman spectroscopy, and spatially or temporally offset Raman spectroscopy (SORS and TORS). Additional emerging Raman techniques, including remote Raman detection, Raman imaging, and Heterodyne imaging, are being developed to further enhance the Raman signal, mitigate fluorescence effects, and monitor hazards at a distance for use in homeland security and defense applications.
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    Combination of LC-MS2 and GC-MS as a Tool to Differentiate Oxidative Metabolites of Zearalenone with Different Chemical Structures (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: Recent studies on the mammalian and fungal metabolism of the mycotoxin zearalenone (ZEN) have disclosed the formation of six regioisomers of monohydroxy-ZEN and its reductive metabolite zearalenol (ZEL). Hydroxylation occurs at the aromatic ring or at one of four positions of the aliphatic macrocycle. In addition, an aliphatic ZEN epoxide, its hydrolysis product, and other products were identified in fungal cultures. In this paper, we report the product ion spectra of the [M-H]− ions of 22 oxidative metabolites of ZEN and ZEL, obtained by LC-MS2 analysis using a linear ion trap mass spectrometer with negative electrospray ionization. The MS2 spectra exhibit qualitative and quantitative differences which allow a clear distinction of most metabolites. Moreover, GC-MS analysis of the trimethylsilylated metabolites yields electron impact mass spectra with numerous fragment ions which can be used as fingerprint to confirm the chemical structure derived by LC-MS2 analysis.
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    A Study of the Deformation, Network, and Aging of Polyethylene Oxide Films by Infrared Spectroscopy and Calorimetric Measurements (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: The calorimetric and infrared (IR) spectroscopy measurements of polyethylene oxide (PEO) are used to evaluate the deformation and relaxation that films experience during a temperature cycle (30°C–90°C–30°C). After melting, the intensity of some bands decreases by 10 to 70%. During the temperature cycle, the C–O band in the 1100 cm−1 region and the C–C–O deformation bands at 650 and 500 cm−1 show some new features. A network of cooperative oxygen-hydrogen interactions between the PEO chains form in films with special history, namely, in thermally treated films, in thin films prepared from gel forming solutions, and in thick films after aging. The interchain interaction network is suggested from the IR absorption bands in the 1200 and 900 cm−1 region and also from small bands at 1144 and 956 cm−1. The network seems absent or reduced in thin films. IR spectroscopy appears a sensitive technique to study chain conformations in PEO films and in other materials where order, disorder, and the formation of intermolecular interactions coexist.
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    Probing Local Environments by Time-Resolved Stimulated Emission Spectroscopy (2012)
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    Publication Date: 2012-06-21
    Description: Time-resolved stimulated emission spectroscopy was employed to probe the local environment of DASPMI (4-(4-(dimethylamino)styryl)-N-methyl-pyridinium iodide) in binary solvents of different viscosity and in a sol-gel matrix. DASPMI is one of the molecules of choice to probe local environments, and the dependence of its fluorescence emission decay on viscosity has been previously used for this purpose in biological samples, solid matrices as well as in solution. The results presented in this paper show that time-resolved stimulated emission of DASPMI is a suitable means to probe the viscosity of local environments. Having the advantage of a higher time resolution, stimulated emission can provide information that is complementary to that obtained from fluorescence decay measurements, making it feasible to probe systems with lower viscosity.
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    On Applicability of a Miniaturised Laser Ablation Time of Flight Mass Spectrometer for Trace Elements Measurements (2012)
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    Publication Date: 2012-06-21
    Description: We present results from mass spectrometric analysis of NIST standard materials and meteoritic samples conducted by a miniaturised laser ablation mass spectrometer designed for space research. The mass analyser supports investigation with a mass resolution (m/Δm) ≈ 500–600 and dynamic range within seven decades. Nevertheless, to maintain an optimal spectral quality laser irradiances lower than ~1 GW/cm2 are applied so far which results in a spread of RSC values. To achieve the quantitative performance of mass analyser, various effects influencing RSC factors have to be investigated. In this paper we investigate influence of laser irradiance, sampling procedure and plasma chemistry on the quantitative elemental and isotopic analysis. The studies indicate necessity for accurate control of laser characteristics and acquisition procedure. A relatively low irradiance applied causes a negligible sample damage and allows for accumulation of large number of waveforms from one sample location. The procedure yields statistically well averaged data and allows a sensitive in-depth analysis. The quantitative analyses of isotopic composition can be performed with accuracy and precision better as 1% and 2%, for isotopic patterns of elements and clusters, respectively. The numerical integration methods would be preferred to achieve more accurate results. The measurements of Allende sample yield detection of Pb isotopic pattern, nevertheless cluster species are readily observed in spectrum and make the elemental analysis of other trace elements difficult due to isobaric interferences. These detections are of a considerable interest because of possible application of the instrument for in situ elemental and isotopic analysis and radiometric dating of solids.
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    Spectroscopy Methods and Applications of the Tor Vergata Laser-Plasma Facility Driven by GW-Level Laser System (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: A review focused on plasma induced on solid target by GW-level pulsed laser source is presented. A description of the Tor Vergata laser-plasma source (TVLPS), at the Tor Vergata University in Rome, is given. Such a facility uses a 1  GW, tabletop, multistage Nd:YAG/Glass laser system, delivering infrared (IR) pulses with nanosecond width and 1064 nm wavelength (TEM00 mode). Its applications are discussed providing: wide analysis of IR → soft X-ray conversion efficiency (1.3–1.55 keV); measures and modeling of line emission in soft X-ray spectra, such as those from zinc plasma near Ne-like Zn XXI and from barium plasma near Ni-like Ba XXIX. Particular attention is devoted to high-n dielectronic Rydberg satellites for finding a useful diagnostic tool for plasma conditions. Dependence of plasma spectra on laser parameters is shown. Finally, microradiography applications are presented for thin biological samples. Images permit to visualize specific structures and detect bioaccumulation sites due to contamination from pollutants.
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    Mass Spectra Analyses of Amides and Amide Dimers of Steviol, Isosteviol, and Steviolbioside (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: The mass spectra of a series of stevioside analogues including the amide and dimer compounds of steviol, isosteviol, and steviolbioside were examined. Positive ion mass spectral fragmentation of new steviol, isosteviol, and steviolbioside amides and the amide dimers are reported and discussed. The techniques included their synthesis procedures, fast-atom bombardment (FAB), and LC/MS/MS mass spectra. Intense [M+H]+ and [M+Na]+ ion peaks were observed on the FAB and ESI spectra. LC/MS/MS also yielded ES+ and ES− ion peaks that fairly agreed with the results of the FAB and ESI studies. Mass spectral analysis of compounds 4p-q, 5a-g, 6, and 7 revealed the different cleavage pathway patterns that can help in identifying the structures of steviolbioside and its amide derivatives.
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    Difference Spectroscopy in the Analysis of the Effects of Coffee Cherry Processing Variables on the Flavor of Brewed Coffee (2012)
    Hindawi
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    Publication Date: 2012-06-21
    Description: Infrared difference spectroscopy was used to study how changes in the processing of Arabica coffee cherries into green beans affected the flavor of coffee brewed from roasted green beans. Paired samples of green beans, in which the drying step or fermentation/washing step in their processing was altered, were roasted and brewed in a standard manner and their ATR-FT-IR spectra obtained. Difference spectra of the 1800 to 1680 cm−1 carbonyl region of water-subtracted spectra of paired samples of these brewed coffees provided data which indicated differences in brewed coffee flavor due to changes in fermentation/washing steps and drying steps involved in the processing of coffee cherries. The role of acid, ketone, aldehyde, ester, lactone, and vinyl ester carbonyl components on the flavor of brewed coffee is proposed that is consistent with the flavors as perceived by the coffee tasters.
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    Infrared Spectroscopic Characterization of CIT-6 and a Family of *BEA Zeolites (2013)
    Hindawi
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    Publication Date: 2013-10-25
    Description: Infrared spectroscopy is known to be a useful tool for identifying local structure changes in zeolites. Infrared spectroscopy is often employed to complement X-ray diffraction data. Local structure changes in zeolite CIT-6 and its zeolite beta (*BEA) analogs caused by calcination, altering framework composition, and ion exchange have been identified with mid- and far-infrared spectroscopy. Differences in the local structures of the samples were observed in mid- and far-infrared spectra, including changes in the intratetrahedral asymmetric stretch, the double-ring mode, and the intratetrahedral bending mode regions. The infrared spectra indicate that calcination or acetic acid extraction changed the structure of CIT-6 to that of zeolite beta (*BEA). Zinc ion exchange or the substitution of aluminum into the framework structure of acetic acid extracted samples retained the CIT-6 structure.
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    The Application of Simple and Easy to Implement Decoupling Pulse Scheme Combinations to Effect Decoupling of Large Values with Reduced Artifacts (2014)
    Hindawi
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    Publication Date: 2014-04-30
    Description: Of the various problems in decoupling one nucleus type from another using standard decoupling pulse schemes for broadband decoupling, a particular challenge is to effect full, artifact-free decoupling when the size of the coupling constant is very large. Herein it is demonstrated that 1H decoupling of the 31P NMR spectrum of diethyl phosphonate HP(=O)(OCH2CH3)2 can be accomplished with reduced artifacts despite the large value of 693 Hz by using a combination of decoupling pulse schemes involving continuous-wave (CW) irradiation and either adiabatic-pulse decoupling (APD), MPF decoupling, or traditional composite-pulse decoupling (CPD) schemes such as WALTZ or GARP. The considered strategy is simple, efficient, and easy to implement on most instruments. The best result was attained for a combination of CW and CPD using GARP with a standard pulse width of 60 μs. Altogether, the advantages of the methodology include low power requirements, complete decoupling, tolerance of a range of large values, large bandwidth for normal-sized values, and the suppression of sidebands.
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    The Low Energy Auger Electron Spectroscopy Lines as an Index of the Ba Overlayer Order on the Ni(110) Surface (2014)
    Hindawi
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    Publication Date: 2014-03-27
    Description: We investigate the interaction of Ba with the Ni(110) surface at elevated temperatures by means of Auger electron spectroscopy and low energy electron diffraction. The results show that annealing of the substrate causes desorption and ordering of the initially amorphous overlayer, resulting in c and structures. It is observed that the induced ordering crucially affects the lineshape of the double Auger transition line Ba(73 eV)N45O23P1, establishing this line as an index of ordering of the Ba overlayer. The underlying physics of this effect is discussed.
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    Graphical Conversion between Compliance and Modulus, Permittivity and Electric Modulus, and Impedance and Admittance (2014)
    Hindawi
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    Publication Date: 2014-11-26
    Description: Spectrometries probing relaxation and retardation phenomena, such as dielectric, mechanical, and impedance spectroscopies, often require the analyses with both susceptibilities spectra and its reciprocals (e.g., complex permittivity and electric modulus, mechanical compliance and mechanical modulus, and impedance and admittance). In the present paper, the geometric relation between and is derived and the procedure to convert into on a Cole-Cole diagram is proposed. This method helps us to relate them intuitively and yields clearer understanding on their interrelations. Moreover, it opens the new route for the geometric approach to derive many mathematical properties of spectra. The relation between peak position of spectrum and that of spectrum and the shape of spectra are discussed on the basis of this method.
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    Estimation of Tadalafil Using Derivative Spectrophotometry in Bulk Material and in Pharmaceutical Formulation (2014)
    Hindawi
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    Publication Date: 2014-05-22
    Description: Four simple, rapid, accurate, precise, reliable, and economical UV-spectrophotometric methods have been proposed for the determination of tadalafil in bulk and in pharmaceutical formulation. “Method A” is first order derivative UV spectrophotometry using amplitude, “method B” is first order derivative UV spectrophotometry using area under curve technique, “method C” is second order derivative UV spectrophotometry using amplitude, and “method D” is second order derivative UV spectrophotometry using area under curve technique. The developed methods have shown best results in terms of linearity, accuracy, precision, and LOD and LOQ for bulk drug and marketed formulation as well. In N,N-dimethylformamide, tadalafil showed maximum absorbance at 284 nm. For “method A” amplitude was recorded at 297 nm while for “method B” area under curve was integrated in the wavelength range of 290.60–304.40 nm. For “method C” amplitude was measured at 284 nm while for “method D” area under curve was selected in the wavelength range of 280.80–286.20 nm. For methods A and B, tadalafil obeyed Lambert-Beer’s law in the range of 05–50 μg/mL while for “methods C and D”, tadalafil obeyed Lambert-Beer’s law in the range of 20–70 μg/mL, and-for “methods A, B, C, and D” the correlation coefficients were found to be  than 0.999.
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    FTIR Spectroscopy Combined with Partial Least Square for Analysis of Red Fruit Oil in Ternary Mixture System (2014)
    Hindawi
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    Publication Date: 2014-05-22
    Description: FTIR spectroscopy is a promising method for quantification of edible oils. Three edible oils, namely, red fruit oil (RFO), corn oil (CO), and soybean oil (SO), in ternary mixture system were quantitatively analyzed using FTIR spectroscopy in combination with partial least square (PLS). FTIR spectra of edible oils in ternary mixture were subjected to several treatments including normal spectra and their derivative. Using PLS calibration, the first derivative FTIR spectra can be exploited for determination of RFO; meanwhile, the second derivative spectra were preferred for determination of CO and SO. The values obtained for the relationship between actual and FTIR predicted values of RFO, CO, and SO were 0.9863, 0.9276, and 0.9693, respectively. The root mean square error of calibration (RMSEC) values obtained were 1.59, 1.72, and 1.60% (v/v) for RFO, CO, and SO, respectively. The result showed that FTIR spectroscopy offers accurate and reliable technique for quantitative analysis of RFO, CO, and SO simultaneously in ternary mixture systems. Besides, the developed method can be extended for analysis of CO and SO as adulterants in RFO.
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    Binding of the Bi (III) Complex of Naringin with β-Cyclodextrin/Calf Thymus DNA: Absorption and Fluorescence Characteristics (2014)
    Hindawi
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    Publication Date: 2014-06-06
    Description: Naringin-Bi (III) complex (Narb) was prepared and analysed by UV-Visible absorption and fluorescence measurements. The inclusion complex of Narb with β-Cyclodextrin (β-CD) was characterized by the UV-Visible absorption, Infrared, scanning dlectron microscopic, and X-ray diffractometric techniques. The stoichiometry of the inclusion complex of Narb with β-CD was 1 : 1 with a binding constant of 5.18 × 102 mol−1 dm3. The interaction of Narb with Calf Thymus DNA (ctDNA) was investigated in the presence and the absence of β-CD. The binding constants for the interaction of Narb with ctDNA in the absence and the presence of β-CD were 1.29 × 105 mol−1 dm3 and 6.89 × 104 mol−1 dm3, respectively. The Stern-Volmer constants for the interaction of Narb with ctDNA in the absence and the presence of β-CD were 1.25 × 104 mol−1 dm3 and 5.10 × 103 mol−1 dm3, respectively. The lowering of the binding affinity and the were observed for the interaction of Narb with ctDNA in the presence of β-CD.
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    Optical Path Length Calibration: A Standard Approach for Use in Absorption Cell-Based IR-Spectrometric Gas Analysis (2014)
    Hindawi
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    Publication Date: 2014-07-18
    Description: We employed a comparison method to determine the optical path length of gas cells which can be used in spectroscopic setup based on laser absorption spectroscopy or FTIR. The method is based on absorption spectroscopy itself. A reference gas cell, whose length is a priori known and desirably traceable to the international system of units (SI), and a gas mixture are used to calibrate the path length of a cell under test. By comparing spectra derived from pressure-dependent measurements on the two cells, the path length of the gas cell under test is determined. The method relies neither on the knowledge of the gas concentration nor on the line strength parameter of the probed transition which is very rarely traceable to the SI and of which the uncertainty is often relatively large. The method is flexible such that any infrared light source and infrared active molecule with isolated lines can be used. We elaborate on the method, substantiate the method by reporting results of this calibration procedure applied to multipass and single pass gas cells of lengths from 0.38 m to 21 m, and compare this to other methods. The relative combined uncertainty of the path length results determined using the comparison method was found to be in the ±0.4% range.
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    A Validated Method for the Quantitation of Ciprofloxacin Hydrochloride Using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (2014)
    Hindawi
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    Publication Date: 2014-02-06
    Description: A quantitative method using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was developed and validated for the estimation of ciprofloxacin in its tablet dosage forms. The solid-state samples were prepared by dilution in dry potassium bromide and were analyzed by FTIR spectrophotometer with DRIFT sampling technique. A linear relationship for the carbonyl peak area centered around 1709 cm−1 was observed in the range of 0.3–1.5% w/w with good correlation coefficient of 0.998. The percent recovery of ciprofloxacin in three marketed tablet dosage forms was in the range of 98.76 ± 0.27. The present reported method is precise, reproducible, and eco-friendly. DRIFTS may have a potential as an alternative method for qualitative and quantitative analysis of ciprofloxacin in bulk drugs and tablet dosage forms.
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    Development and Validation of a Discriminating In Vitro Dissolution Method for Oral Formulations Containing Satranidazole (2014)
    Hindawi
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    Publication Date: 2014-04-25
    Description: The development of a meaningful dissolution procedure for drug products with limited water solubility has been a challenge to the pharmaceutical industry. Satranidazole (BCS Class II drug) is a new nitroimidazole derivative with potent antiamoebic action. There is no official dissolution medium available in the literature. In the present study, parameters such as saturation solubility in different pH medium, dissolution behavior of formulations, influence of sink conditions, stability, and discriminatory effect of dissolution testing were studied for the selection of a proper dissolution medium. Results of solubility data revealed that solubility of Satranidazole decreases with an increase in pH. Satranidazole showed better sink condition in 0.1 N HCl as compared to other media. The drug and marketed formulations were stable in the dissolution media used. An agitation speed of 75 rpm showed a more discriminating drug release profile than 50 rpm. Using optimized dissolution parameters (paddle at 75 rpm, 900 mL 0.1 N HCl) greater than 80% of the label amount is released over 60 minutes. UV-spectroscopic method used was validated for the specificity, linearity, precision, robustness, and solution stability. The method was successfully applied to granular formulations and also to marketed tablets containing 300 mg Satranidazole.
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    Structural Characterization of Amadori Rearrangement Product of Glucosylated Nα-Acetyl-Lysine by Nuclear Magnetic Resonance Spectroscopy (2014)
    Hindawi
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    Publication Date: 2014-04-18
    Description: Maillard reaction is a nonenzymatic reaction between reducing sugars and free amino acid moieties, which is known as one of the most important modifications in food science. It is essential to characterize the structure of Amadori rearrangement products (ARPs) formed in the early stage of Maillard reaction. In the present study, the Nα-acetyl-lysine-glucose model had been successfully set up to produce ARP, Nα-acetyl-lysine-glucose. After HPLC purification, ARP had been identified by ESI-MS with intense [M+H]+ ion at 351 m/z and the purity of ARP was confirmed to be over 90% by the relative intensity of [M+H]+ ion. Further structural characterization of the ARP was accomplished by using nuclear magnetic resonance (NMR) spectroscopy, including 1D 1H NMR and 13C NMR, the distortionless enhancement by polarization transfer (DEPT-135) and 2D 1H-1H and 13C-1H correlation spectroscopy (COSY) and 2D nuclear overhauser enhancement spectroscopy (NOESY). The complexity of 1D 1H NMR and 13C NMR was observed due to the presence of isomers in glucose moiety of ARP. However, DEPT-135 and 2D NMR techniques provided more structural information to assign the 1H and 13C resonances of ARP. 2D NOESY had successfully confirmed the glycosylated site between 10-N in Nα-acetyl-lysine and 7′-C in glucose.
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    Understanding and Control of High Temperature Oxidation Flaws of Low-Density Poly(ethylene) with Raman Spectroscopy (2014)
    Hindawi
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    Publication Date: 2014-06-06
    Description: Studies of high temperature oxidation of polyethylene are not much present in the literature though it can really be a problem especially in polymer production and processing. This study aims to detect oxidation flaws in polyethylene and to determine their impact on polymer structure and properties. Besides, we suggest a method via PLS-regression to determine the degree of flaws that can occur during polymer processing due to oxidation. Several kinds of oxidation flaws were reproduced in laboratory at 150°C in an oven operating in air and Raman spectroscopy analysis was performed on each sample. Using statistical tools as chemometrics on these spectra, we have built a Partial Least Square (PLS) model able to predict the oxidation degree of flaws. Interpretation of the model construction and further characterization tests show that oxidation can be followed with the evolution of the crystalline carbon group and of the created carbonyl functions. Finally we suggest possible mechanisms which can explain the high temperature oxidation process in LPDE, and we link them to the modification of the material properties.
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    Orientation and Optical Polarized Spectra (380–900 nm) of Methylene Blue Crystals on a Glass Surface (2013)
    Hindawi
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    Publication Date: 2013-07-24
    Description: The crystallographic directions of the crystal toward the vector of polarized light can accurately be positioned, so the information that we gain from polarized spectra can be consistently interpreted according to known crystal structure. The orientation and optical properties of the methylene blue (MB) crystals were analyzed by XRD, XRPD, and polarized VIS-NIR spectroscopy. Cationic dye, MB, was polymerized into crystals on a glass slate. The blue color crystals showed pronounced dichroism, twin lamellar structure and bladed to fibrous habit. According to XRD data, [010] direction lies perpendicular to the crystal surface, so we recognized it as (0k0) face, while [100] and [001] directions coincide with crystal elongation and crystal thickness respectively. In this paper, the polarized spectra of MB crystal are presented, measured with the aim of acquisition of referent values, which could be helpful for the identification of MB molecular aggregation.
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    Carbon Dioxide Capture from Ambient Air Using Amine-Grafted Mesoporous Adsorbents (2013)
    Hindawi
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    Publication Date: 2013-04-29
    Description: Anthropogenic emissions of carbon dioxide (CO2) have been identified as a major contributor to climate change. An attractive approach to tackle the increasing levels of CO2 in the atmosphere is direct extraction via absorption of CO2 from ambient air, to be subsequently desorbed and processed under controlled conditions. The feasibility of this approach depends on the sorbent material that should combine a long lifetime with nontoxicity, high selectivity for CO2, and favorable thermodynamic cycling properties. Adsorbents based on pore-expanded mesoporous silica grafted with amines have previously been found to combine high CO2 adsorption capacity at low partial pressures with operational stability under highly defined laboratory conditions. Here we examine the real potential and functionality of these materials by using more realistic conditions using both pure CO2, synthetic air, and, most importantly, ambient air. Through a combination of thermogravimetric analysis and Fourier transform infrared (TGA-FTIR) spectroscopy we address the primary functionality and by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy the observed degradation of the material on a molecular level.
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    Line Intensity Measurements of the Band of Ethylene (12C2H4) (2013)
    Hindawi
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    Publication Date: 2013-07-11
    Description: From the four high-resolution FTIR absorbance spectra recorded at a spectral resolution of 0.0063 cm−1, 123 line intensities belonging to the band of 12C2H4 were measured and fit. The upper state rovibrational constants up to sextic terms determined using a Watson's -reduced Hamiltonian model in representation were used to calculate the line intensities of the band. Results of the experimental fit of the line intensities agree well with those obtained by calculations.
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    Simple Atomic Absorption Spectroscopic and Spectrophotometric Methods for Determination of Pioglitazone Hydrochloride and Carvedilol in Pharmaceutical Dosage Forms (2014)
    Hindawi
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    Publication Date: 2014-05-19
    Description: This study represents simple atomic absorption spectroscopic and spectrophotometric methods for determination of pioglitazone hydrochloride (PGZ-HCl) and carvedilol (CRV) based on formation of ion-pair associates between drugs and inorganic complex, bismuth(III) tetraiodide (Method A) and between drugs and organic acidic dyes, fast green and orange G (Method B). Method A is based on formation of ion-pair associate between drugs and bismuth(III) tetraiodide in acidic medium to form orange-red ion-pair associates, which can be quantitatively determined by two different procedures. The formed ion-pair associate is extracted by methylene chloride, dissolved in acetone, dried, and then decomposed by hydrochloric acid, and bismuth content is determined by direct atomic absorption spectrometric technique (Procedure 1) or extracted by methylene chloride, dissolved in acetone, and quantified spectrophotometrically at 490 nm (Procedure 2). Method B is based on formation of ion-pair associate between drugs and either fast green dye or orange G dye in acidic medium to form ion-pair associates. The formed ion-pair associate is extracted by methylene chloride and quantified spectrophotometrically at 630 nm (for fast green dye method) or 498 nm (for orange G dye method). Optimal experimental conditions have been studied. Both methods are applied for determination of the drugs in tablets without interference.
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    New Simple Spectrophotometric Method for the Simultaneous Estimation of Paracetamol and Flupirtine Maleate in Pure and Pharmaceutical Dosage Form (2014)
    Hindawi
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    Publication Date: 2014-05-13
    Description: A new, simple, precise, accurate, reproducible, and efficient Vierordt’s method or simultaneous equation method was developed and validated for simultaneous estimation of paracetamol and flupirtine maleate in pure and pharmaceutical dosage form. The method was based on the measurement of absorbance at two wavelengths 245 nm and 344.5 nm, of paracetamol and flupiritine maleate in 0.1 N HCl correspondingly. Calibration curves of paracetamol and flupiritine maleate were found to be linear in the concentration ranges of 5–15 μg/mL and 1.53–4.61 μg/mL, respectively, with their correlation coefficient values (R2) 0.999. LOD and LOQ were 185.90 ng/mL and 563.38 ng/mL for paracetamol and 78.89 ng/mL and 239.06 ng/mL for flupiritine maleate. In the precision study, the % RSD value was found within limits (%). The percentage recovery at various concentration levels varied from 99.18 to 100.02% for paracetamol and 98.47 to 100.09% for flupiritine maleate confirming that the projected method is accurate. It could be concluded from the results obtained in the present investigation that this method for simultaneous estimation of paracetamol and flupirtine maleate in pure and tablet dosage form is simple, accurate, precise, and economical. The proposed method can be applied successfully for the simultaneous estimation of paracetamol and flupiritine maleate in pure and pharmaceutical dosage form.
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    Two-Pulse Phase Modulation Based Decoupling Schemes for Removing Heteronuclear Spin Interactions in the NMR Spectroscopy of Isotropic Systems: An Analysis Using Experiments and Numerical Simulations (2014)
    Hindawi
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    Publication Date: 2014-05-16
    Description: Heteronuclear spin interactions in solids and anisotropic liquids can be removed by phase modulated decoupling sequences with frequency sweep, such as -TPPM and its variants. The performance of these sequences in isotropic spin systems with regard to the experimental parameters, phase angle, and decoupler offset is presented here. A comparison is made with other commonly used heteronuclear decoupling schemes in liquids, namely, WALTZ-16, GARP, and MLEV. Also, the trajectories of nuclear magnetization vector of abundant nuclei in a simple spin system during TPPM and -TPPM decoupling sequences are traced out using computer simulations.
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    Spectroscopic Characterization of Stability and Interaction of Pd-Ag Complexes (2014)
    Hindawi
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    Publication Date: 2014-05-09
    Description: Colloidal metal nanoparticles are of great interest because of their use as catalysts, photocatalysts, adsorbents, and sensors as well as their application in optical, electronic, and magnetic devices. Supported bimetallic systems represent a large part of heterogeneous catalysts which have been used in various reactions important in the chemical, petrochemical, and oil industry. Pd-Ag bimetallic nanocatalysts have become vitally important in some of the petrochemical industry’s processes like hydrogenation of C2–C5 olefins. A heat-treatment method for the preparation of well-stable Pd-Ag complexes is demonstrated using water, concentrated HCl and concentrated nitric acid as media. The stability and interaction of Pd-Ag complexes were characterized by UV-vis absorption spectroscopy. Pd-Ag bimetallic nanoparticles of spherical cubic and octahedral shape in the range of average particle size of 20–60 nm have been prepared and characterized by transmission electron microscopy (TEM).
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    New Kinetic Spectrophotometric Method for Determination of Fexofenadine Hydrochloride in Pharmaceutical Formulations (2014)
    Hindawi
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    Publication Date: 2014-06-30
    Description: A simple and sensitive kinetic spectrophotometric method was developed for the determination of fexofenadine hydrochloride in bulk and pharmaceutical preparations. The method is based on a kinetic investigation of the oxidation reaction of fexofenadine using alkaline potassium permanganate as an oxidizing agent at room temperature. The reaction is followed spectrophotometrically by measuring the increase of absorbance owing to the formation of manganate ion at 610 nm. The initial rate and fixed time (at 15 min) methods are utilized for construction of calibration graphs. All the reaction conditions for the proposed method have been studied. The linearity range was found to be 2.5–50.0 μg mL−1 with detection limit of 0.055 μg mL−1 for both initial rate and fixed time methods. The proposed method was applied successfully for the determination of fexofenadine in pharmaceutical formulations; the percentage recoveries were 99.98–101.96%. The results obtained were compared statistically with those obtained by the official method and showed no significant differences regarding accuracy and precision.
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    Quantum Chemical and Spectroscopic Investigations of (Ethyl 4 hydroxy-3-((E)-(pyren-1-ylimino)methyl)benzoate) by DFT Method (2014)
    Hindawi
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    Publication Date: 2014-07-10
    Description: In the present work we have reported the optimized ground state geometry, harmonic vibrational frequencies, NMR chemical shifts, NBO analysis, and molecular electrostatic potential surface map of the title compound using DFT/B3LYP/6-311++G(2d, 2p) level of theory. We have compared our calculated results with the experimentally obtained values and found that both are in close agreement with each other. We have used the gauge-invariant atomic orbital (GIAO) approach to calculate the NMR (13C and 1H) chemical shifts using Gaussian 09 package. TD-DFT (time-dependent DFT) approach has been used to simulate the electronic spectra of the title compound in order to account for excited states. Other molecular properties such as HOMO-LUMO energies, NBO analysis, and PED distribution analysis have been studied and reported using DFT/B3LYP/6-311++G(2d, 2p) level of theory.
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    Uniform versus Nonuniform Scaling of Normal Modes Predicted by Ab Initio Calculations: A Test on 2-(2,6-Dichlorophenyl)-N-(1,3-thiazol-2yl) Acetamide (2014)
    Hindawi
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    Publication Date: 2014-07-11
    Description: A test on calculated vibrational modes of 2-(2,6-dichlorophenyl)-N-(1,3-thiazol-2yl) acetamide using ab initio density functional method has been performed. The calculated harmonic vibrational frequencies are scaled via two schemes, uniform, , and nonuniform, . Scaled vibrational modes are compared with experimental FTIR bands. A good correlation is shown between scaled frequencies with the correlation coefficient, . This clearly shows that both schemes efficiently reproduce observed spectrum. However, a close investigation of individual normal modes reveals that nonuniform scaling performs much better than uniform scaling especially in the high frequency region.
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    The Nanofabrication and Application of Substrates for Surface-Enhanced Raman Scattering (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: Surface-enhanced Raman scattering (SERS) was discovered in 1974 and impacted Raman spectroscopy and surface science. Although SERS has not been developed to be an applicable detection tool so far, nanotechnology has promoted its development in recent decades. The traditional SERS substrates, such as silver electrode, metal island film, and silver colloid, cannot be applied because of their enhancement factor or stability, but newly developed substrates, such as electrochemical deposition surface, Ag porous film, and surface-confined colloids, have better sensitivity and stability. Surface enhanced Raman scattering is applied in other fields such as detection of chemical pollutant, biomolecules, DNA, bacteria, and so forth. In this paper, the development of nanofabrication and application of surface-enhanced Ramans scattering substrate are discussed.
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    Highly Sensitive Filter Paper Substrate for SERS Trace Explosives Detection (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: We report on a novel and extremely low-cost surface-enhanced Raman spectroscopy (SERS) substrate fabricated depositing gold nanoparticles on common lab filter paper using thermal inkjet technology. The paper-based substrate combines all advantages of other plasmonic structures fabricated by more elaborate techniques with the dynamic flexibility given by the inherent nature of the paper for an efficient sample collection, robustness, and stability. We describe the fabrication, characterization, and SERS activity of our substrate using 2,4,6-trinitrotoluene, 2,4-dinitrotoluene, and 1,3,5-trinitrobenzene as analytes. The paper-based SERS substrates presented a high sensitivity and excellent reproducibility for analytes employed, demonstrating a direct application in forensic science and homeland security.
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    Development of a Novel Embedded Relay Lens Microscopic Hyperspectral Imaging System for Cancer Diagnosis: Use of the Mice with Oral Cancer to Be the Example (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: This paper develops a novel embedded relay lens microscopic hyperspectral imaging system (ERL-MHSI) with high spectral resolution (nominal spectral resolution of 2.8 nm) and spatial resolution (30 μm × 10 μm) for cancer diagnosis. The ERL-MHSI system has transmittance and fluorescence mode. The transmittance can provide the morphological information for pathological diagnosis, and the fluorescence of cells or tissue can provide the characteristic signature for identification of normal and abnormal. In this work, the development of the ERL-MHSI system is discussed and the capability of the system is demonstrated by diagnosing early stage oral cancer of twenty mice in vitro. The best sensitivity for identifying normal cells and squamous cell carcinoma (SCC) was 100%. The best specificity for identifying normal cells and SCC was 99%. The best sensitivity for identifying normal cells and dysplasia was 99%. The best specificity for identifying normal cells and dysplasia was 97%. This work also utilizes fractal dimension to analyze the morphological information and find the significant different values between normal and SCC.
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    Vital Autofluorescence: Application to the Study of Plant Living Cells (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: The application of various microscopy methods such as luminescence microscopy, microspectrofluorimetry and laser-scanning confocal microscopy has been considered as an approach to study the autofluorescence of plant living cells—from cell diagnostics up to modelling the cell-cell contacts and cell interactions with fluorescent biologically active substances. It bases on the direct observations of secretions released from allelopathic and medicinal species and the cell-donor interactions with cell-acceptors as biosensors (unicellular plant generative and vegetative microspores). Special attention was paid to the interactions with pigmented and fluorescing components of the secretions released by the cells-donors from plant species. Colored components of secretions are considered as histochemical dyes for the analysis of cellular mechanisms at the cell-cell contacts and modelling of cell-cell interactions. The fluorescence of plant biosensors was also recommended for the testing of natural plant excretions as medical drugs.
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    Protein Interactions Investigated by the Raman Spectroscopy for Biosensor Applications (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: Interaction and surface binding characteristics of staphylococcal protein A (SpA) and an anti-Escherichia coli immunoglobulin G (IgG) were studied using the Raman spectroscopy. The tyrosine amino acid residues present in the α-helix structure of SpA were found to be involved in interaction with IgG. In bulk interaction condition the native structure of proteins was almost preserved where interaction-related changes were observed in the overall secondary structure (α-helix) of SpA. In the adsorbed state, the protein structure was largely modified, which allowed the identification of tyrosine amino acids involved in SpA and IgG interaction. This study constitutes a direct Raman spectroscopic investigation of SpA and IgG (receptor-antibody) interaction mechanism in the goal of a future biosensor application for detection of pathogenic microorganisms.
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    Raman Spectroscopy at High Pressures (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: Raman spectroscopy is one of the most informative probes for studies of material properties under extreme conditions of high pressure. The Raman techniques have become more versatile over the last decades as a new generation of optical filters and multichannel detectors become available. Here, recent progress in the Raman techniques for high-pressure research and its applications in numerous scientific disciplines including physics and chemistry of materials under extremes, earth and planetary science, new materials synthesis, and high-pressure metrology will be discussed.
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    Raman Spectroscopy for Quantitative Analysis of Point Defects and Defect Clusters in Irradiated Graphite (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: We report the development of Raman spectroscopy as a powerful tool for quantitative analysis of point defect and defect clusters in irradiated graphite. Highly oriented pyrolytic graphite (HOPG) was irradiated by 25 keV He+ and 20 keV D+ ions. Raman spectroscopy and transmission electron microscopy revealed a transformation of irradiated graphite into amorphous state. Annealing experiment indicated a close relation between Raman intensity ratio and vacancy concentration. The change of Raman spectra under irradiation was empirically analyzed by “disordered-region model,” which assumes the transformation from vacancy-contained region to disordered region. The model well explains the change of Raman spectra and predicts the critical dose of amorphization, but the nature of the disordered region is unclear. Then, we advanced the model into “dislocation accumulation model,” assigning the disordered region to dislocation dipole. Dislocation accumulation model can simulate the irradiation time dependencies of Raman intensity ratio and the c-axis expansion under irradiation, giving a relation between the absolute concentration of vacancy and Raman intensity ratio, suggesting an existence of the barrier on the mutual annihilation of vacancy and interstitial.
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    Vibrational Spectrum of HMX at CO2 Laser Wavelengths: A Combined DRIFT and LPAS Study (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: The vibrational spectrum of solid standard HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) was investigated. Two spectroscopic techniques were adopted for their different sensitivity and resolution. A preliminary survey of the absorption bands of the compound was performed in the 8000–400 cm−1 spectral range by employing the diffuse reflectance infrared Fourier transform (DRIFT) technique at room temperature. The high-resolution line spectrum of HMX was obtained in the 9.2–10.8 μm spectral range by laser photoacoustic spectroscopy (LPAS) method, using a line tuneable 10 W stabilised cw CO2 laser light source. By comparing the data collected with the two techniques in the common frequency range, a very good agreement was observed.
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    Integrated Band Intensities of Ethylene (12 (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: The integrated band intensities of ethylene (12C2H4) in the 640–3260 cm−1 region were determined by Fourier transform infrared (FTIR) spectroscopy. The infrared absorbance spectra of the
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    Study on the Interaction of Bovine Serum Albumin with Ceftriaxone and the Inhibition Effect of Zinc (II) (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: The mechanism of the interaction between bovine serum albumin (BSA) and ceftriaxone with and without zinc (II) (Zn2+) was studied employing fluorescence, ultraviolet (UV) absorption, circular dichroism (CD), and synchronous fluorescence spectral methods. The intrinsic fluorescence of BSA was quenched by ceftriaxone in a static quenching mode, which was authenticated by Stern-Volmer calculations. The binding constant, the number of binding sites, and the thermodynamic parameters were obtained, which indicated a spontaneous and hydrophobic interaction between BSA and ceftriaxone regardless of Zn2+. Changes in UV absorption, CD, and synchronous fluorescence spectral data are due to the microenvironment of amide moieties in BSA molecules. In the BSA-ceftriaxone-Zn2+ system, Zn2+ must first interact with ceftriaxone forming a complex, which inhibits BSA binding to ceftriaxone. The present work uses spectroscopy to elucidate the mechanism behind the interaction between BSA and ceftriaxone in the presence and absence of Zn2+. The BSA and ceftriaxone complex provides a model for studying drug-protein interactions and thus may further facilitate the study of drug metabolism and transportation.
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    Detection of Bacillus anthracis Spores Using Peptide Functionalized SERS-Active Substrates (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: The need for portable technologies that can rapidly identify biological warfare agents (BWAs) in the field remains an international priority as expressed at the 2011 Biological Weapons Convention. In recent years, the ability of surface-enhanced Raman spectroscopy (SERS) to rapidly detect various BWAs at very low concentrations has been demonstrated. However, in the specific case of Bacillus anthracis, differentiation at the species level is required since other bacilli are common in the environment, representing potential false-positive responses. To overcome this limitation, we describe the use of a peptide attached to the SERS-active metal that selectively binds Bacillus anthracis-Sterne as the target analyte. Using this approach, 109  B. anthracis-Sterne spores/mL produced an intense dipicolinic acid spectrum upon the addition of acetic acid, while the same concentration and treatment of B. cereus and B. subtilis did not.
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    Raman Spectroscopy for Homeland Security Applications (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: Raman spectroscopy is an analytical technique with vast applications in the homeland security and defense arenas. The Raman effect is defined by the inelastic interaction of the incident laser with the analyte molecule’s vibrational modes, which can be exploited to detect and identify chemicals in various environments and for the detection of hazards in the field, at checkpoints, or in a forensic laboratory with no contact with the substance. A major source of error that overwhelms the Raman signal is fluorescence caused by the background and the sample matrix. Novel methods are being developed to enhance the Raman signal’s sensitivity and to reduce the effects of fluorescence by altering how the hazard material interacts with its environment and the incident laser. Basic Raman techniques applicable to homeland security applications include conventional (off-resonance) Raman spectroscopy, surface-enhanced Raman spectroscopy (SERS), resonance Raman spectroscopy, and spatially or temporally offset Raman spectroscopy (SORS and TORS). Additional emerging Raman techniques, including remote Raman detection, Raman imaging, and Heterodyne imaging, are being developed to further enhance the Raman signal, mitigate fluorescence effects, and monitor hazards at a distance for use in homeland security and defense applications.
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    Demonstrated Wavelength Portability of Raman Reference Data for Explosives and Chemical Detection (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: As Raman spectroscopy continues to evolve, questions arise as to the portability of Raman data: dispersive versus Fourier transform, wavelength calibration, intensity calibration, and in particular the frequency of the excitation laser. While concerns about fluorescence arise in the visible or ultraviolet, most modern (portable) systems use near-infrared excitation lasers, and many of these are relatively close in wavelength. We have investigated the possibility of porting reference data sets from one NIR wavelength system to another: We have constructed a reference library consisting of 145 spectra, including 20 explosives, as well as sundry other compounds and materials using a 1064 nm spectrometer. These data were used as a reference library to evaluate the same 145 compounds whose experimental spectra were recorded using a second 785 nm spectrometer. In 128 cases of 145 (or 88.3% including 20/20 for the explosives), the compounds were correctly identified with a mean “hit score” of 954 of 1000. Adding in criteria for when to declare a correct match versus when to declare uncertainty, the approach was able to correctly categorize 134 out of 145 spectra, giving a 92.4% accuracy. For the few that were incorrectly identified, either the matched spectra were spectroscopically similar to the target or the 785 nm signal was degraded due to fluorescence. The results indicate that imported data recorded at a different NIR wavelength can be successfully used as reference libraries, but key issues must be addressed: the reference data must be of equal or higher resolution than the resolution of the current sensor, the systems require rigorous wavelength calibration, and wavelength-dependent intensity response should be accounted for in the different systems.
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    Mass Spectra Analyses of Amides and Amide Dimers of Steviol, Isosteviol, and Steviolbioside (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: The mass spectra of a series of stevioside analogues including the amide and dimer compounds of steviol, isosteviol, and steviolbioside were examined. Positive ion mass spectral fragmentation of new steviol, isosteviol, and steviolbioside amides and the amide dimers are reported and discussed. The techniques included their synthesis procedures, fast-atom bombardment (FAB), and LC/MS/MS mass spectra. Intense [M+H]+ and [M+Na]+ ion peaks were observed on the FAB and ESI spectra. LC/MS/MS also yielded ES+ and ES− ion peaks that fairly agreed with the results of the FAB and ESI studies. Mass spectral analysis of compounds 4p-q, 5a-g, 6, and 7 revealed the different cleavage pathway patterns that can help in identifying the structures of steviolbioside and its amide derivatives.
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    Effects of Molecular Structure on Intramolecular Charge Carrier Transport in Dithieno [3,2-b: 2,3-d] Pyrrole-Based Conjugated Copolymers (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: Intramolecular mobility of positive charge carriers in conjugated polymer films based on dithieno [2,3-b: 2,3-d] pyrrole (DTP) is studied by time-resolved microwave conductivity (TRMC). A series of DTP homopolymer and copolymers combined with phenyl, 2,2-biphenyl, thiophene, 2,2-bithiophene, and 9,9-dioctylfluorene were synthesized by Suzuki-Miyaura and Yamamoto coupling reactions. Polymers containing DTP unit are reported to show high value of hole mobility measured by FET method, and this type of polymers is expected to have stable HOMO orbitals which are important for hole transportation. Among these copolymers, DTP coupled with 9,9-dioctylfluorene copolymer showed the highest charge carrier mobility as high as 1.7 cm2/Vs, demonstrating an excellent electrical property on rigid copolymer backbones.
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    Raman Microimaging Using a Novel Multifiber-Based Device: A Feasibility Study on Pharmaceutical Tablets (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: Raman microimaging is a potential analytical technique in health field and presents many possible pharmaceutical applications. In this study, we tested a micrometer spatial resolution probe coupled to a portable Raman imager via an indexed multifiber bundle. At the level of the probe, the fibers were arranged in a circular geometry in order to fit to the pupil of an objective. The imaging potential of this Raman system was assessed on pharmaceutical-like pellets. We showed that this setup permits to record, nearly in real time, Raman images with a micrometer resolution. The collected images revealed a marked heterogeneity in chemicals distribution. Further investigations will be led on cells and biological tissues to evaluate the potential of this Raman imaging device for biomedical applications.
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    Fiber Optic Coupled Raman Based Detection of Hazardous Liquids Concealed in Commercial Products (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: Raman spectroscopy has been widely proposed as a technique to nondestructively and noninvasively interrogate the contents of glass and plastic bottles. In this work, Raman spectroscopy is used in a concealed threat scenario where hazardous liquids have been intentionally mixed with common consumer products to mask its appearance or spectra. The hazardous liquids under consideration included the chemical warfare agent (CWA) simulant triethyl phosphate (TEP), hydrogen peroxide, and acetone as representative of toxic industrial compounds (TICs). Fiber optic coupled Raman spectroscopy (FOCRS) and partial least squares (PLS) algorithm analysis were used to quantify hydrogen peroxide in whiskey, acetone in perfume, and TEP in colored beverages. Spectral data was used to evaluate if the hazardous liquids can be successfully concealed in consumer products. Results demonstrated that FOC-RS systems were able to discriminate between nonhazardous consumer products and mixtures with hazardous materials at concentrations lower than 5%.
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    Resonance-Enhanced Raman Spectroscopy on Explosives Vapor at Standoff Distances (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: Resonance-enhanced Raman spectroscopy has been used to perform standoff measurements on nitromethane (NM), 2,4-DNT, and 2,4,6-TNT in vapor phase. The Raman cross sections for NM, DNT, and TNT in vapor phase have been measured in the wavelength range 210–300 nm under laboratory conditions, in order to estimate how large resonance enhancement factors can be achieved for these explosives. The results show that the signal is enhanced up to 250,000 times for 2,4-DNT and up to 60,000 times for 2,4,6-TNT compared to the nonresonant signal at 532 nm. Realistic outdoor measurements on NM in vapor phase at 13 m distance were also performed, which indicate a potential for resonance Raman spectroscopy as a standoff technique for detection of vapor phase explosives. In addition, the Raman spectra of acetone, ethanol, and methanol were measured at the same wavelengths, and their influence on the spectrum from NM was investigated.
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    A Study of the Deformation, Network, and Aging of Polyethylene Oxide Films by Infrared Spectroscopy and Calorimetric Measurements (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: The calorimetric and infrared (IR) spectroscopy measurements of polyethylene oxide (PEO) are used to evaluate the deformation and relaxation that films experience during a temperature cycle (30°C–90°C–30°C). After melting, the intensity of some bands decreases by 10 to 70%. During the temperature cycle, the C–O band in the 1100 cm−1 region and the C–C–O deformation bands at 650 and 500 cm−1 show some new features. A network of cooperative oxygen-hydrogen interactions between the PEO chains form in films with special history, namely, in thermally treated films, in thin films prepared from gel forming solutions, and in thick films after aging. The interchain interaction network is suggested from the IR absorption bands in the 1200 and 900 cm−1 region and also from small bands at 1144 and 956 cm−1. The network seems absent or reduced in thin films. IR spectroscopy appears a sensitive technique to study chain conformations in PEO films and in other materials where order, disorder, and the formation of intermolecular interactions coexist.
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    New Possibility for REE Determination in Oil (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: A novel approach of rare earth elements (REE) determination in crude oil is suggested. Special application of countercurrent chromatography (CCC) is used as a sample pretreatment tool. An oil sample is continuously pumped through the rotating coil column (RCC) as a mobile phase, while an aqueous phase (nitric acid solution) is retained as a stationary phase. Two phases are kept well mixed and agitated, but there is no emulsion at the interface under the chosen conditions. Special features of CCC give an opportunity to vary the volume of oil samples to be analyzed from 10 mL to 1 L or more. Trace metals are preconcentrated into 10 mL of stationary phase (acidic solutions) pumped out of the column so that analysis can be easily determined with inductively coupled plasma mass spectrometry (ICP-MS) without additional sample preparation procedures. Optimal concentration of nitric acid in the stationary phase for preconcentration of REE from oil by CCC has been investigated. The combination of CCC with ICP-MS gives the possibility to develop a rapid, reliable, and accurate method of trace metal including rare earth elements (REE) determination in crude oils and oil products. Such method could be an alternative for unexpanded and expensive neutron-activation analysis (NAA).
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    On Applicability of a Miniaturised Laser Ablation Time of Flight Mass Spectrometer for Trace Elements Measurements (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: We present results from mass spectrometric analysis of NIST standard materials and meteoritic samples conducted by a miniaturised laser ablation mass spectrometer designed for space research. The mass analyser supports investigation with a mass resolution (
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    Application of Raman Spectroscopy to the Biooxidation Analysis of Sulfide Minerals (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: We report the application of confocal laser scanning microscopy CLSM and Raman spectroscopy on the (bio)chemical oxidation of pyrite and chalcopyrite, in order to understand how surface sulfur species (S
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    Gas Chromatography Electron Ionization Mass Spectral Analysis of Thio Analogues of Pyrimidine Bases: 5-Bromo-2,4-di-o-(m- and p-) chloro- (bromo-)benzylthiouracils and 6-methyluracils (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: Electron ionization (EI) mass spectral fragmentation routes of twelve 5-bromo-2,4-di-o-(m- and p-) chloro- (bromo-)benzyl-thiouracils and 6-methyluracils are investigated. The compounds studied are analyzed using gas chromatography/mass spectrometry (GC/MS). Fragmentation pathways, whose elucidation is assisted by accurate mass measurements and metastable transitions, are discussed. Correlation between the abundances of the selected fragment ions of the compounds investigated is discussed. The data obtained make grounds for distinction of structural isomers.
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    A Novel Method for Bacterial UTI Diagnosis Using Raman Spectroscopy (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: The current state of the art on bacterial classification using Raman and Surface Enhanced Raman Spectroscopy (SERS) for the purpose of developing a rapid and more accurate method for urinary tract infection (UTI) diagnosis is presented. SERS, an enhanced version of Raman offering much increased sensitivity, provides complex biochemical information which, in conjunction with advanced analysis and classification techniques, can become a valuable diagnostic tool. The variety of metal substrates used for SERS, including silver and gold colloids, as well as nanostructured metal surfaces, is reviewed. The challenges in preprocessing noisy and complicated spectra and the various methods used for feature creation as well as a novel method using spectral band ratios are described. The various unsupervised and supervised classification methods commonly used for SERS spectra of bacteria are evaluated. Current research on transforming SERS into a valuable clinical tool for the diagnosis of UTIs is presented. Specifically, the classification of bacterial spectra (a) as positive or negative for an infection, (b) as belonging to a particular species of bacteria, and (c) as sensitive or resistant to an antibiotic are described. This work can lead to the development of novel technology with extremely important benefits for public health.
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    Unilateral NMR: A Noninvasive Tool for Monitoring In Situ the Effectiveness of Intervention to Reduce the Capillary Raise of Water in an Ancient Deteriorated Wall Painting (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: Portable unilateral NMR was used to quantitatively map in a fully noninvasive way the moisture distribution in an ancient deteriorated wall painting before and after an intervention to reduce the capillary raise of water through the wall. Maps obtained at a depth of 0.5 cm clearly showed the path of the capillary raise and indicated that, after the intervention, the moisture level was reduced. Maps obtained by measuring the first layers of the wall painting were affected by the critical environmental conditions of the second hypogeous level of St. Clement Basilica, Rome, and by the presence of salts efflorescence and encrustations on the surface of the wall painting. The morphology and the elemental composition of salts investigated by SEM-EDS indicated that efflorescences and encrustations were mostly constituted of gypsum and calcite. The presence of these salts is explained with the presence of high concentration of carbon dioxide and sulphur-rich particles due to pollution which, along with the high-moisture level and the extremely feeble air circulation, cause recarbonation and sulphation processes on the plaster surface.
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    A Simulation Study of the Fundamental Vibrational Shifts of HCl Diluted in Ar, Kr, and Xe: Anharmonic Corrections Effects (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: We have calculated the vibrational solvent shifts of the fundamental bands of HCl diluted in Ar, Kr, and Xe solutions at different thermodynamic conditions by means of the molecular dynamics technique and a model for the isotropic part of the interaction depending on the vibration. The theoretical vibrational shifts, which were compared with the available experimental data, have been determined by considering both, the usual linear Buckingham terms and the nonlinear anharmonic corrections, and the latter omitted in a previous work for the HCl in Ar and Kr. We have found that the Buckingham contributions dominate the solvent shifts of the fundamental bands of HCl in Ar, Kr, and Xe, although the anharmonic shifts’ present significant greater values than those obtained previously for N2 diluted in liquid Ar and pure liquid N2, both at normal conditions. We have analyzed the solvent shifts influence of the linear and quadratic (in the vibrational coordinate) oscillator-bath interaction terms and also the Dunham intramolecular potential effects on the anharmonic contributions.
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    QCLAS and CRDS-Based CO Quantification as Aimed at in Breath Measurements (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: Laser-spectrometric methods to derive absolute and traceable carbon monoxide (CO) amount fractions in exhaled human breath could be of advantage for early disease detection as well as for treatment monitoring. As proof-of-principle laboratory experiment, we employed intra-pulse and continuous wave (cw) quantum cascade laser spectroscopy (QCLAS), both at 4.6 μm. Additional experiments were carried out applying cw cavity ring-down spectroscopy (CRDS) with a CO sideband laser and a QCL. We emphasize metrological data quality objectives, thatis, traceability and uncertainty, which could serve as essential benefits to exhaled breath measurements. The results were evaluated and compared on a 100 μmol/mol CO level using the two QCLAS spectrometers, and the cw CO sideband laser CRDS setup. The relative standard uncertainties of the pulsed and the cw QCLAS CO amount fraction results were ±4.8 and ±2.8%, respectively, that from the CO sideband laser CRDS was ±2.7%. Sensitivities down to a 3 nmol/mol CO level were finally demonstrated and quantified by means of cw CRDS equipped with a QCL yielding standard uncertainties of about ±2.5 that are exclusively limited by the available line strength figure quality. With this study we demonstrate the achieved comparability of CO quantifications, adhering metrological principles.
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    Combination of LC-MS2 and GC-MS as a Tool to Differentiate Oxidative Metabolites of Zearalenone with Different Chemical Structures (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: Recent studies on the mammalian and fungal metabolism of the mycotoxin zearalenone (ZEN) have disclosed the formation of six regioisomers of monohydroxy-ZEN and its reductive metabolite zearalenol (ZEL). Hydroxylation occurs at the aromatic ring or at one of four positions of the aliphatic macrocycle. In addition, an aliphatic ZEN epoxide, its hydrolysis product, and other products were identified in fungal cultures. In this paper, we report the product ion spectra of the [M-H]− ions of 22 oxidative metabolites of ZEN and ZEL, obtained by LC-MS2 analysis using a linear ion trap mass spectrometer with negative electrospray ionization. The MS2 spectra exhibit qualitative and quantitative differences which allow a clear distinction of most metabolites. Moreover, GC-MS analysis of the trimethylsilylated metabolites yields electron impact mass spectra with numerous fragment ions which can be used as fingerprint to confirm the chemical structure derived by LC-MS2 analysis.
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    Recent Applications of Ion Mobility Spectrometry in Diagnosis of Vaginal Infections (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: Vaginal infections (vaginosis) globally affect more than 15% of the female population of reproductive age. However, diagnosis of vaginosis and differentiating between the three common types: bacterial vaginosis (BV), vulvovaginal candidiasis (VVC), and trichomoniasis are challenging. Elevated levels of the biogenic amines, trimethylamine (TMA), putrescine, and cadaverine have been found in vaginal discharge fluid of women with vaginosis. Ion mobility spectrometry (IMS) is particularly suitable for measurement of amines even in complex biological matrices due to their high proton affinity and has been shown to be suitable for the diagnosis of vaginal infections. Recent developments that have increased the accuracy of the technique for diagnosis of BV and simplified sample introduction are described here.
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    Design Considerations for a Portable Raman Probe Spectrometer for Field Forensics (2013)
    Hindawi
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    Publication Date: 2013-01-22
    Description: Raman spectroscopy has been shown to be a viable method for explosives detection. Currently most forensic Raman systems are either large, powerful instruments for laboratory experiments or handheld instruments for in situ point detection. We have chosen to examine the performance of certain benchtop Raman probe systems with the goal of developing an inexpensive, portable system that could be used to operate in a field forensics laboratory to examine explosives-related residues or samples. To this end, a rugged, low distortion line imaging dispersive Raman spectrograph was configured to work at 830 nm laser excitation and was used to determine whether the composition of thin films of plastic explosives or small (e.g., ≤10 μm) particles of RDX or other explosives or oxidizers can be detected, identified, and quantified in the field. With 300 mW excitation energy, concentrations of RDX and PETN can be detected and reconstructed in the case of thin Semtex smears, but further work is needed to push detection limits of areal dosages to the ~1 μg/cm2 level. We describe the performance of several probe/spectrograph combinations and show preliminary data for particle detection, calibration and detection linearity for mixed compounds, and so forth.
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    Highly Sensitive Filter Paper Substrate for SERS Trace Explosives Detection (2012)
    Hindawi
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    Publication Date: 2012-10-18
    Description: We report on a novel and extremely low-cost surface-enhanced Raman spectroscopy (SERS) substrate fabricated depositing gold nanoparticles on common lab filter paper using thermal inkjet technology. The paper-based substrate combines all advantages of other plasmonic structures fabricated by more elaborate techniques with the dynamic flexibility given by the inherent nature of the paper for an efficient sample collection, robustness, and stability. We describe the fabrication, characterization, and SERS activity of our substrate using 2,4,6-trinitrotoluene, 2,4-dinitrotoluene, and 1,3,5-trinitrobenzene as analytes. The paper-based SERS substrates presented a high sensitivity and excellent reproducibility for analytes employed, demonstrating a direct application in forensic science and homeland security.
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    Detection of Bacillus anthracis Spores Using Peptide Functionalized SERS-Active Substrates (2012)
    Hindawi
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    Publication Date: 2012-10-03
    Description: The need for portable technologies that can rapidly identify biological warfare agents (BWAs) in the field remains an international priority as expressed at the 2011 Biological Weapons Convention. In recent years, the ability of surface-enhanced Raman spectroscopy (SERS) to rapidly detect various BWAs at very low concentrations has been demonstrated. However, in the specific case of Bacillus anthracis, differentiation at the species level is required since other bacilli are common in the environment, representing potential false-positive responses. To overcome this limitation, we describe the use of a peptide attached to the SERS-active metal that selectively binds Bacillus anthracis-Sterne as the target analyte. Using this approach, 109  B. anthracis-Sterne spores/mL produced an intense dipicolinic acid spectrum upon the addition of acetic acid, while the same concentration and treatment of B. cereus and B. subtilis did not.
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    Development of a Novel Embedded Relay Lens Microscopic Hyperspectral Imaging System for Cancer Diagnosis: Use of the Mice with Oral Cancer to Be the Example (2012)
    Hindawi
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    Publication Date: 2012-11-27
    Description: This paper develops a novel embedded relay lens microscopic hyperspectral imaging system (ERL-MHSI) with high spectral resolution (nominal spectral resolution of 2.8 nm) and spatial resolution (30 μm × 10 μm) for cancer diagnosis. The ERL-MHSI system has transmittance and fluorescence mode. The transmittance can provide the morphological information for pathological diagnosis, and the fluorescence of cells or tissue can provide the characteristic signature for identification of normal and abnormal. In this work, the development of the ERL-MHSI system is discussed and the capability of the system is demonstrated by diagnosing early stage oral cancer of twenty mice in vitro. The best sensitivity for identifying normal cells and squamous cell carcinoma (SCC) was 100%. The best specificity for identifying normal cells and SCC was 99%. The best sensitivity for identifying normal cells and dysplasia was 99%. The best specificity for identifying normal cells and dysplasia was 97%. This work also utilizes fractal dimension to analyze the morphological information and find the significant different values between normal and SCC.
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    The Nanofabrication and Application of Substrates for Surface-Enhanced Raman Scattering (2012)
    Hindawi
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    Publication Date: 2012-12-20
    Description: Surface-enhanced Raman scattering (SERS) was discovered in 1974 and impacted Raman spectroscopy and surface science. Although SERS has not been developed to be an applicable detection tool so far, nanotechnology has promoted its development in recent decades. The traditional SERS substrates, such as silver electrode, metal island film, and silver colloid, cannot be applied because of their enhancement factor or stability, but newly developed substrates, such as electrochemical deposition surface, Ag porous film, and surface-confined colloids, have better sensitivity and stability. Surface enhanced Raman scattering is applied in other fields such as detection of chemical pollutant, biomolecules, DNA, bacteria, and so forth. In this paper, the development of nanofabrication and application of surface-enhanced Ramans scattering substrate are discussed.
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    Fiber Optic Coupled Raman Based Detection of Hazardous Liquids Concealed in Commercial Products (2013)
    Hindawi
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    Publication Date: 2013-01-02
    Description: Raman spectroscopy has been widely proposed as a technique to nondestructively and noninvasively interrogate the contents of glass and plastic bottles. In this work, Raman spectroscopy is used in a concealed threat scenario where hazardous liquids have been intentionally mixed with common consumer products to mask its appearance or spectra. The hazardous liquids under consideration included the chemical warfare agent (CWA) simulant triethyl phosphate (TEP), hydrogen peroxide, and acetone as representative of toxic industrial compounds (TICs). Fiber optic coupled Raman spectroscopy (FOCRS) and partial least squares (PLS) algorithm analysis were used to quantify hydrogen peroxide in whiskey, acetone in perfume, and TEP in colored beverages. Spectral data was used to evaluate if the hazardous liquids can be successfully concealed in consumer products. Results demonstrated that FOC-RS systems were able to discriminate between nonhazardous consumer products and mixtures with hazardous materials at concentrations lower than 5%.
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