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排序方式: 共有181条查询结果,搜索用时 78 毫秒
91.
Geographical origin of Sauvignon Blanc wines predicted by mass spectrometry and metal oxide based electronic nose 总被引:1,自引:0,他引:1
Analysis of 34 Sauvignon Blanc wine samples from three different countries and six regions was performed by gas chromatography-mass spectrometry (GC-MS). Linear discriminant analysis (LDA) showed that there were three distinct clusters or classes of wines with different aroma profiles. Wines from the Loire region in France and Australian wines from Tasmania and Western Australia were found to have similar aroma patterns. New Zealand wines from the Marlborough region as well as the Australian ones from Victoria were grouped together based on the volatile composition. Wines from South Australia region formed one discrete class. Seven analytes, most of them esters, were found to be the relevant chemical compounds that characterized the classes. The grouping information obtained by GC-MS, was used to train metal oxide based electronic (MOS-Enose) and mass spectrometry based electronic (MS-Enose) noses. The combined use of solid phase microextraction (SPME) and ethanol removal prior to MOS-Enose analysis, allowed an average error of prediction of the regional origins of Sauvignon Blanc wines of 6.5% compared to 24% when static headspace (SHS) was employed. For MS-Enose, the misclassification rate was higher probably due to the requirement to delimit the m/z range considered. 相似文献
92.
Pau Arroyo Salvador Gil Amalia Muoz Pedro Palanca Joaquin Sanchis Vicent Sanz 《Journal of molecular catalysis. A, Chemical》2000,160(2):403-408
Oxo-transfer reactions of a variety of substrates in DMF or methanol using polymer-supported molybdenyl thioglycolate (PSMT) have been investigated. The clean oxidation of Me2PhP, n-butanethiol or benzoin to yield Me2PhPO, disulfide or benzil, respectively, occurs in high yield. In the presence of air or pyridine N-oxide, a catalytic cycle is accomplished which goes on until the completion of the substrate. 相似文献
93.
María Del Mar Graciani Amalia Rodríguez Gaspar Fernández María Muñoz María luisa Moyá 《国际化学动力学杂志》2008,40(12):845-582
The reaction of methyl 4‐nitrobenzenesulfonate (MNB) and Br? has been studied in water–glycerol (GLY) alkyltrimethylammonium bromide micellar solutions, with the weight percentage of glycerol up to 50%. A pseudophase kinetic model was used for quantitatively discussing the kinetic data. Results showed that the equilibrium‐binding constant for the organic substrate molecules to the cationic micelles decreases upon increasing the amount of glycerol present in the micellar reaction media. The second‐order rate constant of the reaction in the micellar pseudophase is practically independent of wt% of GLY. Similar results were found in other water–organic solvent alkyltrimethylammonium bromide micellar solutions for the same process. However, the dependence of the reaction rate, for a given surfactant concentration, on the wt% of organic solvent is weaker for glycerol than for the other organic solvents. This was explained by considering that the cationic micellar ionization degree is nearly independent of wt% GLY. As a consequence, bromide ions concentration in the interfacial region (the reaction site) does not change by varying wt% of GLY. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 845–582, 2008 相似文献
94.
We report on the errors obtained by comparing in- and out-of-plane displacements calculated from the sensitivity matrix with all its components, and when only the component from the largest contributing of each one of the three interferometers is considered. Divergent illumination is considered in the evaluation of sensitivity vector to measure displacement vector components. This analysis is performed for a flat elastic target which is loaded in the x-direction and after in the z-direction. The technique applied is electronic speckle pattern interferometry. 相似文献
95.
Gaspar Fernndez Amalia Rodríguez María del Mar Graciani María Muoz María Luisa Moy 《国际化学动力学杂志》2003,35(2):45-51
The reaction methyl 4‐nitrobenzenesulfonate + Cl? was studied in hexadecyltrimethylammonium chloride (CTAC) in the absence and presence of 0.1 M NaCl, as well as in mixed CTAC/Triton X‐100 (polyoxyethylene(9.5)octylphenyl ether) aqueous micellar solutions with CTAC molar fractions of 0.9, 0.8, 0.7, and 0.6. Conductivity measurements were used to obtain critical micellar concentrations and micellar ionization degrees of the various micellar reaction media. From these data, thermodynamic information on the cationic/nonionic mixed micellar solutions was obtained. Micellar effects on the observed rate constant were explained by pseudophase kinetic models. The estimated second‐order rate constants in the micellar pseudophase of the different micellar reaction media showed that pure CTAC and mixed CTAC/Triton X‐100 micelles, at the high cationic surfactant molar fractions studied, provide reaction sites of similar characteristics at the interfacial region. This was in agreement with previous structural studies carried out on mixed CTAC/Triton X‐100 micellar solutions. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 35: 45–51, 2003 相似文献
96.
[CpRu]‐Catalyzed Carbene Insertions into Epoxides: 1,4‐Dioxene Synthesis through SN1‐Like Chemistry with Retention of Configuration 下载免费PDF全文
Dr. Thierry Achard Cecilia Tortoreto Dr. Amalia I. Poblador‐Bahamonde Dr. Laure Guénée Prof. Thomas Bürgi Prof. Jérôme Lacour 《Angewandte Chemie (International ed. in English)》2014,53(24):6140-6144
Rather than lead to the usual deoxygenation pathway, metal carbenes derived from α‐diazo‐β‐ketoesters undergo three‐atom insertions into epoxides using a combination of 1,10‐phenanthroline and [CpRu(CH3CN)3][BArF] as the catalyst. Original 1,4‐dioxene motifs are obtained as single regio‐ and stereoisomers. A perfect syn stereochemistry (retention, e.r. up to 97:3) is observed for the ring opening, which behaves as an SN1‐like transformation. 相似文献
97.
Multifunctional Redox Polymers: Electrochrome,Polyelectrolyte, Sensor,Electrode Modifier,Nanoparticle Stabilizer,and Catalyst Template 下载免费PDF全文
Christophe Deraedt Amalia Rapakousiou Yanlan Wang Dr. Lionel Salmon Melanie Bousquet Prof. Didier Astruc 《Angewandte Chemie (International ed. in English)》2014,53(32):8445-8449
Simple “click” polycondensation metallopolymers of redox‐robust bis(ethynyl)biferrocene (biFc) and di(azido) poly(ethylene glycol) (PEG400 and PEG1000) were designed for multiple functions including improvement of water solubility and biocompatibility, the introduction of mixed valency and sensing capabilities, and as nanoparticle stabilizers for catalysis. 相似文献
98.
María Amalia Rodríguez María Muñoz María del Mar Graciani Gaspar Fernández María Luisa Moyá 《国际化学动力学杂志》2007,39(6):346-352
The reaction methyl 4‐nitrobenzenesulfonate + Br? has been studied in water‐ethylene glycol cetyltrialkylammonium bromide (alkyl = methyl, ethyl, propyl, and butyl) micellar solutions by changing surfactant concentration as well as the weight percentage of ethylene glycol present in the bulk phase. The pseudophase model was adequate to rationalize quantitatively the micellar kinetic effects. Information about the influence of the head group size on the second‐order rate constant of the process and on the binding equilibrium constant of the organic substrate to the cationic micelles in water–ethylene glycol mixtures was obtained. Kinetic data taken from the literature were compared to those obtained in this work in order to examine the different effects produced by an alcohol that is localized in the bulk phase, such as ethylene glycol, with those caused by an alcohol that distributes between the bulk and micellar pseudophases, such as 1‐butanol. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 346–352, 2007 相似文献
99.
Iordanidis A Garcia-Guinea J Strati A Gkimourtzina A Papoulidou A 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,78(2):874-887
This study concerns the investigation of pigments and efflorescence phenomena on the wall paintings of Kastoria, a rural, non-metropolitan Byzantine town. A large number of representative samples were collected from the murals of three churches, dated to post-Byzantine era (14th-17th c. AD). The identified pigments for the red colour were hematite (Fe2O3), cinnabar (HgS) and minium (Pb3O4), while brown and yellow colours were attributed to mixtures of ochres (Fe-oxides and hydroxides) and lime. The utilization of admixtures of iron, lead and mercury compounds was also attested in order to render specific tones on the painted surfaces. Black and dark blue hues were prepared using black carbon and Mn in some cases. Grey colours were assigned to a mixture of black carbon and lime. Green colour is rather attributed to admixtures of Fe-rich minerals and lime and not to the commonly used green earths. Baryte (BaSO4) was also evidenced as a filler or extender. Phosphorous was detected and connected to proteinaceous material and Mo and Sb were traced which are probably affiliated to Fe-oxides. Regarding efflorescing salts, the determined compounds are: calcite, dolomite, gypsum, halite, nitratine, natron and mirabilite, all of which are related to temperature and humidity changes and moisture fluctuations inside the wall paintings. 相似文献
100.
Amalia Halim Alexander Shapiro Anna Eliasson Lantz Sidsel Marie Nielsen 《Transport in Porous Media》2014,101(1):1-15
Bacterial selective plugging is one of the mechanisms through which microorganisms can be applied for enhanced oil recovery, as bacteria can plug the water-swept zones of a reservoir, thus altering the flow paths and improving sweep efficiency. However, complete understanding of the penetration behavior of bacteria is lacking, especially in chalk formations where characteristic pore throat sizes are comparable with the sizes of bacterial cells. In this study, two bacterial strains, Bacillus licheniformis 421 (spore-forming) and Pseudomonas putida K12 (non-spore forming) were used to investigate the penetration of bacteria into chalk and its effect on permeability reduction. The core plugs were produced from Stevns Klint outcrop with low permeability (2–4 mD) and with pore sizes comparable to bacterial sizes. Both types of bacteria were able to penetrate and to be transported through the cores to some extent. A significantly higher number of B. licheniformis 421 was detected in the effluents as compared to P. putida K12. It was demonstrated that the spore-forming B. licheniformis 421 penetrates in the form of spores. P. putida K12 is found to penetrate the core, however, in smaller numbers compared to B. licheniformis. It was shown that both bacteria, under different injection concentrations, were capable of plugging the porous rock, as indicated by reduction of the core permeability. An incubation period of 12 days did not allow the permeability to return to initial condition. Based on the results it can be concluded that, when injected into chalk, spore forming bacteria have higher chance to survive and penetrate into deeper formation; and both types of bacteria may cause permeability reduction. 相似文献