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981.
The two minerals diadochite and destinezite of formula Fe2(PO4,SO4)2(OH)· 6H2O have been characterised by Raman spectroscopy and complemented with infrared spectroscopy. Both these minerals are found in soils and are identical except for their morphology. Diadochite is amorphous whereas destinezite is highly crystalline. The spectra of diadochite are broad and ill defined, whereas the spectra of destinezite are intense and well defined. Bands are assigned to phosphate and sulfate stretching and bending modes. Two symmetric stretching modes for both phosphate and sulfate support the concept of non‐equivalent phosphate and sulfate units in the mineral structure. Multiple water bending and stretching modes imply that non‐equivalent water molecules in the structure exist with different hydrogen‐bond strengths. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
982.
José Luis Pérez Pavón Sara Herrero MartínCarmelo García Pinto Bernardo Moreno Cordero 《Journal of chromatography. A》2009,1216(32):6063-6070
A methodology based on the coupling of a headspace autosampler with a GC and a MS detector operating in SIM mode has been developed for the determination of volatile organic compounds (THMs and BTEX) in soils. The GC device used is equipped with a programmable temperature vaporizer (PTV) packed with Tenax-TA® to introduce the samples (the injection mode used was solvent vent), and a modular accelerated column heater (MACH™) to control column temperature. The proposed measurement procedure reduces the sample pretreatment step to a minimum. Combined use of solvent vent injection mode and mass spectrometry detection allows a highly sensitive method to be proposed, with limits of detection of the order of ng/kg for all the target compounds. Furthermore, the capillary column used allows rapid separations of compounds in less than 4.60 min, affording a very short total analysis cycle time of 9 min. 相似文献
983.
Joél Smet Sara Seneca Boel De Paepe Ann Meulemans Helene Verhelst Jules Leroy Linda De Meirleir Willy Lissens Rudy Van Coster 《Electrophoresis》2009,30(20):3565-3572
Complex V, site of the final step in oxidative phosphorylation, uses the proton gradient across the inner mitochondrial membrane for the production of ATP. It is a multi‐subunit complex composed of a catalytic domain (F1) and a membrane domain (F0) linked by two stalks. Subcomplexes of complex V containing the F1 domain have previously been reported in small series of patients. We report the results in tissue samples and/or cultured skin fibroblasts studied by blue native PAGE followed by activity staining in the gel. Catalytically active subcomplexes of complex V were detected in 66 tissues originating from 53 patients. In 29 of the latter (55%), a mitochondrial DNA (mtDNA) defect was identified. Twelve patients had a pathogenic point mutation in a mitochondrial tRNA, one a large mtDNA deletion, 12 showed mtDNA depletion and four had a mutation in the MT‐ATP6 gene. We conclude that the presence of subcomplexes of complex V is a valuable indicator in the detection of mtDNA defects. 相似文献
984.
Giovanni Cerioni Elias Maccioni Maria Cristina Cardia Sara Vigo Francesca Mocci 《Magnetic resonance in chemistry : MRC》2009,47(9):727-733
Two series of 2,5‐diaryl‐1,3,4‐oxadiazolines have been studied by multinuclear magnetic resonance and density functional theory calculations. A full NMR spectroscopic characterization has been performed and excellent remote Hammett correlations (σp or ) have been found for para substitution in the two aryl rings through at least 11 bonds, notwithstanding the presence in the path of atoms that should act as insulators and a lack of correlation for some of the intermediate atoms. The computational investigation on the electronic delocalization, performed with the ACID (anisotropy of the induced current density) method, reveals indeed that electrons are delocalized in almost the entire molecule despite the presence of the insulators. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
985.
Sara Fateixa Mrcia C. Neves Adelaide Almeida Joo Oliveira Tito Trindade 《Colloids and surfaces. B, Biointerfaces》2009,74(1):304-308
Submicron particles of amorphous SiO2 have been used to grow Ag2S nanophases at their surfaces. SEM and TEM analysis showed morphological well-defined nanocomposite particles consisting of Ag2S nanocrystals dispersed over the silica surfaces. These SiO2/Ag2S nanocomposites were investigated as anti-fungal agents against Aspergillus niger in different experimental conditions, including as nanofillers in cellulosic fibres. The anti-fungal activity in these composite systems is suggested to result from a synergistic effect due to Ag2S anti-fungal centres and the SiO2 surfaces in promoting the adsorption of the fungus. 相似文献
986.
Sara J. Palmer J. Kristóf Veronika Vágvölgyi Erzsébet Horváth R. L. Frost 《Journal of Thermal Analysis and Calorimetry》2009,96(2):449-454
The mechanism for the decomposition of hydrotalcite remains unsolved. Controlled rate thermal analysis enables this decomposition pathway to be explored. The thermal decomposition of hydrotalcites with hexacyanoferrate(II) and hexacyanoferrate(III) in the interlayer has been studied using controlled rate thermal analysis technology. X-ray diffraction shows the hydrotalcites have a d(003) spacing of 10.9 and 11.1 Å which compares with a d-spacing of 7.9 and 7.98 Å for the hydrotalcite with carbonate or sulphate in the interlayer. Calculations show dehydration with a total loss of 7 moles of water proving the formula of hexacyanoferrate(II) intercalated hydrotalcite is Mg6Al2(OH)16[Fe(CN)6]0.5·7H2O and 9.0 moles for the hexacyanoferrate(III) intercalated hydrotalcite with the formula of Mg6Al2(OH)16[Fe(CN)6]0.66·9H2O. CRTA technology indicates the partial collapse of the dehydrated mineral. Dehydroxylation combined with CN unit loss occurs in two isothermal stages at 377 and 390°C for the hexacyanoferrate(III) and in a single isothermal process at 374°C for the hexacyanoferrate(III) hydrotalcite. 相似文献
987.
N. Voyer A. Soisnard Sara J. Palmer W. N. Martens R. L. Frost 《Journal of Thermal Analysis and Calorimetry》2009,96(2):481-485
Zn-Al hydrotalcites and Cu-Al hydrotalcites were synthesised by coprecipitation method and analysed by X-ray diffraction (XRD)
and thermal analysis coupled with mass spectroscopy. These methods provide a measure of the thermal stability of the hydrotalcite.
The XRD patterns demonstrate similar patterns to that of the reference patterns but present impurities attributed to Zn(OH)2 and Cu(OH)2. The analysis shows that the d003 peak for the Zn-Al hydrotalcite gives a spacing in the interlayer of 7.59 ? and the estimation
of the particle size by using the Debye-Scherrer equation and the width of the d003 peak is 590 ?. In the case of the Cu-Al
hydrotalcite, the d003 spacing is 7.57 ? and the size of the diffracting particles was determined to be 225 ?.
The thermal decomposition steps can be broken down into 4 sections for both of these hydrotalcites. The first step decomposition
below 100°C is caused by the dehydration of some water absorbed. The second stage shows two major steps attributed to the
dehydroxylation of the hydrotalcite. In the next stage, the gas CO2 is liberated over a temperature range of 150°C. The last reactions occur over 400°C and involved CO2 evolution in the decomposition of the compounds produced during the dehydroxylation of the hydrotalcite. 相似文献
988.
Jeff E. Prest Sara J. Baldock Peter R. Fielden Nicholas J. Goddard Bernard J. Treves Brown 《Analytical and bioanalytical chemistry》2009,394(5):1299-1305
The use of malonic acid as a complexing agent has enabled a new method to be devised to allow the determination of magnesium
to be made using miniaturised isotachophoresis. Using a leading electrolyte of 10 mmol L−1 caesium hydroxide and 2 mmol L−1 malonic acid at pH 5.1 gave the method a high specificity towards magnesium. Investigations using a poly(methyl methacrylate)
chip device with an integrated conductivity detector showed that no interference from calcium, strontium, barium and sodium
should occur. The method was found to be linear over the range of magnesium concentrations from 0.625 to 75 mg L−1 and the limit of detection was calculated to be 0.45 mg L−1. Separations were demonstrated with water samples but the procedure should also be applicable to more complex sample matrices
such as inorganic explosive residues, blood or urine. 相似文献
989.
Roberto Paolesse Luca Tortora Donato Monti Sara Nardis Manuela Stefanelli Arnaldo D’Amico Corrado Di Natale 《Procedia Chemistry》2009,1(1):180-183
A facile and straightforward way to deposit nanostructured porphyrin films onto quartz surfaces is presented. The particular peripheral functionalization on the macrocycle is exploited to drive the formation of aggregates in solution, which then spontaneously deposit as ordered solid layers. Film deposition is then achieved by simple dipping the quartz slide into a solution containing porphyrin aggregates and waiting the formation of the related thin films. QCMs covered with different metalloporphyrin derivatives have been exposed to some model VOCs, showing in general good performances especially in all the cases where film morphology is fundamental for sensing interactions. 相似文献
990.
Ray L. Frost Henry J. Spratt Sara J. Palmer 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,72(5):984-988
Near-infrared (NIR), X-ray diffraction (XRD) and infrared (IR) spectroscopy have been applied to hydrotalcites of the formula Mg6 (Fe,Al)2(OH)16(CO3)·4H2O formed by intercalation with the carbonate anion as a function of divalent/trivalent cationic ratio. Such hydrotalcites were found to show variation in the d-spacing attributed to the size of the cation. In the IR (1750–4000 cm−1), the position of all bands except those at approximately 3060 cm−1 shift to higher wavenumbers as the cation ratio increases. Conversely, at wavenumbers below 1000 cm−1, the bands shift to lower wavenumbers as the cation ratio increases. A water bending mode at higher wavenumbers was also observed which indicates that the water is strongly hydrogen bonded. In the NIR spectrum between 8000 and 12,000 cm−1, there is a broad feature which is attributed to electronic bands of the ferrous ion and low intensity sharp bands due to overtones of the OH stretching vibrations. It is also apparent from this region that Fe2+ substitutes for Mg2+. The intensity of bands at 7750 and 5200 cm−1 increases as the cation ratio increases in the NIR spectrum. Hydrotalcites with a magnesium amount 3 and 4 times greater than that of aluminium and iron combined, in the lower wavenumber region of the NIR spectrum, have very similar spectral profiles. This work has shown that hydrotalcites with different divalent/trivalent ratios can be synthesised and characterised by infrared spectroscopy. 相似文献