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911.
M. P. Sánchez Sánchez J. M. Salas Peregrin M. A. Romero Molina 《Monatshefte für Chemie / Chemical Monthly》1987,118(8-9):883-891
Some news thiopyrimidine derivatives and complexes [4-amino-5-nitroso-6-oxo-1,2,3,6-tetrahydro-2-thio-pyrimidine (TANH), its 2-methylthio derivative (MTH), the ammonium salt ofTANH (sTANH) and six new complexes of formulas: Rh(MT)2Cl · 2H2O, Pd(MTH)2Cl2, Pt(MTH)2Cl4, Au(MTH)Cl3 Pd(TANH)2Cl2 and Au(TAN
–)Cl] have been synthesized and characterized by elemental analysis, IR and1H-NMR spectroscopy techniques. The thermal behaviour of all compounds has also been studied.
Rh(III), Pd(II), Pt(IV) und Au(III) Komplexe von 2-Thiopyrimidin Derivaten
Zusammenfassung Es wurden einige neue Thiopyrimidinderivate und deren Komplexe synthetisiert und mittels Elementaranalyse, IR und1H-NMR charakterisiert: 4-Amino-5-nitroso-6-oxo-1,2,3,6-tetrahydro-2-thio-pyrimidin (TANH), dessen 2-Methylthio-Derivat (MTH), das Ammoniumsalz vonTANH (sTANH) und sechs neue Komplexe der Formeln Rh(MT)2Cl · 2H2O, Pd(MTH)2Cl2, Pt(MTH)2Cl4, Au(MTH)Cl3, Pd(TANH)2Cl2 und Au(TAN –)Cl. Das thermische Verhalten der Verbindungen wurde ebenfalls untersucht.相似文献
912.
V. V. Dotsenko S. G. Krivokolysko A. N. Chernega V. P. Litvinov 《Russian Chemical Bulletin》2007,56(7):1431-1436
A new stereoselective method for the synthesis of trans-isomers of 2-amino-4-aryl-5-benzoyl-4,5-dihydrothiophene-3-carbonitriles was proposed. The method involves base-catalyzed
reactions of phenacyl thiocyanate with 3-(het)aryl-2-cyanoprop-2-enethioamides. (4R,5S/4S,5R)-2-Amino-5-benzoyl-4-(2-chlorophenyl)-4,5-ihydrothiophene-3-carbonitrile was structurally characterized by X-ray diffraction
analysis.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1379–1383, July, 2007. 相似文献
913.
This research was aimed
to investigate the role of clay on the combustion and kinetic behavior of
crude oils in limestone matrix. For this purpose, simultaneous TG (thermogravimetry)
and DTA (differential thermal analysis) experiments were performed at three
different heating rates as 10–15 and 20°C min–1,
respectively. A uniform trend of decreasing activation energies was observed
with the addition of clay. It was concluded that clays surface area affects
the values of Arrhenius constant, while it is the catalytic properties of
clay, which lower the activation energies of all the reactions, involved in
the combustion process. 相似文献
914.
In the present study, aluminium and mechanically alloyed (36 h) Fe/B (50 wt%) are mixed. Al+20 (wt%) Fe/B mixture has been studied by differential thermal analysis to determine the aluminium quantity that is supposed to melt and afterwards does not solidify as it reacts with Fe/B powder. The different areas between endothermic reaction (melting peak) and exothermic reaction (solidification peak) allow in knowing the quantity of aluminium that reacts with Fe/B and the amount of intermetallic phases formed at high temperature. In order to follow the process, compacts were sintered at different temperatures (700, 800, 900, 1000 and 1200 °C), in N2/10H2/0.1CH4 atmosphere. Microstructure was evaluated by image analysis and the results obtained by both techniques are compared. 相似文献
915.
对梅州农村饮用水中的重金属元素进行了监测和分析,选择Fe,Mn,Zn,Cu,Ag,Pb,Cd七种元素为检测指标。从实验结果来看,Cu,Ag,Cd含量低,未超标;Fe,Mn,Zn,Pb有超标现象:按其危害程度,Pb,Mn的超标是急需解决的问题。 相似文献
916.
This document reviews the most relevant mass spectrometry approaches to selenium (Se) speciation in high-Se food supplements in terms of qualitative and quantitative Se speciation and Se-containing species identification, with special reference to high-Se yeast, garlic, onions and Brazil nuts. Important topics such as complexity of Se speciation in these materials and the importance of combining Se-specific detection and molecule-specific determination of the particular species of this element in parallel with chromatography, to understand their nutritional role and cancer preventive properties are critically discussed throughout. The versatility and potential of mass spectrometric detection in this field are clearly demonstrated. Although great advances have been achieved, further developments are required, especially if speciatedcertified reference materials (CRMs) are to be produced for validation of measurements of target Se-containing species in Se-food supplements. 相似文献
917.
In this study, chemometric techniques such as cluster analysis (CA), discriminant analysis (DA), principal component analysis (PCA) and partial least squares (PLS) were used to analyse the wastewater dataset to identify the factors which affect the composition of sewage of domestic origin, spatial and temporal variations, similarity/dissimilarity among the wastewater characteristics of cis- and trans-drains and discriminating variables. Samples collected from 24 wastewater drains in Lucknow city and from three sites on Gomti river in the month of January/February, May, August and November during the period of 5 years (1994-1999) were characterized for 32 parameters. The multivariate techniques successfully described the similarities/dissimilarities among the sewage drains on the basis of their wastewater characteristics and sources signifying the effect of routine domestic/commercial activities in respective drainage areas. Spatial and seasonal variations in wastewater composition were also determined successfully. CA generated six groups of drains on the basis of similar wastewater characteristic. PCA provided information on seasonal influence and compositional differences in sewage generated by domestic and industrial waste dominated drains and showed that drains influenced by mixed industrial effluents have high organic pollution load. DA rendered six variables (TDS, alkalinity, F, TKN, Cd and Cr) discriminating between cis- and trans-drains. PLS-DA showed dominance of Cd, Cr, NO3, PO4 and F in cis-drains wastewater. The results suggest that biological-process based STPs could treat wastewater both from the cis- as well as trans-drains, however, prior removal of toxic metals will be required from the cis-drains sewage. Further, seasonal variations in wastewater composition and pollution load could be the guiding factor for determining the STPs design parameters. The information generated would be useful in selection of process type and in designing of the proposed sewage treatment plants (STPs) for safe disposal of wastewater. 相似文献
918.
D. J. Burlett 《Journal of Thermal Analysis and Calorimetry》2004,75(2):531-544
The transfer of heat through an elastomeric matrix is important for both the processing of the material and its subsequent
lifetime. Thermal conductivity can be used to evaluate the influence of different polymers and fillers on heat transfer. Additionally,
the dispersion of the filler has an effect on heat transfer and thermal conductivity measurements can be used to provide semi-quantitative
estimations of filler dispersion. The degradation of sulfur-crosslinked elastomer systems has been studied for many years.
The degradation of the crosslinks (changes in sulfur rank) and degradation of the polymer backbone by thermal and/or oxidative
processes have been studied extensively using many techniques including thermal analysis (references). However, the degradation
of the crosslinked-polymer 'network' is less well understood. The relationship of the crosslink network to this degradation
process is a key to both the long term and higher temperature performance of the sulfur-crosslinked elastomer. The changes
in physical properties observed upon exposure of sulfur-crosslinked elastomers can be monitored using dynamic mechanical analysis.
Subsequently, other thermal techniques can be used to monitor the chemistry that is occurring during these degradations. Thermal
desorption/mass spectroscopy and dynamic scanning calorimetry are used to complete the picture of the degradation processes
taking place. Examples of these techniques will be provided to illustrate the utility of the analytical approach, the chemistry
involved in these degradation processes and the effect of changes in the polymer, cure package and other ingredients.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
919.
920.
A spectrophotometric method has been developed for the simultaneous determination ofo-cresol andm-cresol in water by reaction withp-aminophenol (PAP). Three different methodologies have been assayed; (i) batch analysis, after reaction in an alkaline medium in the presence of dissolved molecular oxygen as oxidizing agent, (ii) a stopped-flow procedure, carried out in the presence of KIO4 and (iii) a flow injection method based on the same approach. The batch procedure requires 22 min for the full development of colour witho-cresol and 12 min form-cresol. In the stopped-flow mode, using KIO4 and a reaction time of 12 min, better sensitivity can be obtained for both compounds and limits of detection of 10 g 1–1 foro-cresol and 30 g 1–1 form-cresol were found. The flow injection method has a lower sensitivity but permits more than 80 injections per hour. Based on the different maximum absorbance wavelengths obtained for the reaction products of PAP witho-cresol (614 nm) andm-cresol (632 nm), both compounds can be simultaneously determined in water samples and recoveries of 90 to 115% were found in spiked water samples of different types. 相似文献