Synthesis and Structure of 〔Cu(μ-C_6H_5COO)_2(C_4H_8O)〕_2

1mTRODUCT1ONBinuclearcoppercomplexesareimportantnotonlyincoordinationchemistryandmagnetostructuralstudiesbutalsoinpracticalapplication.tliInanattempttoseekthedisPersionandemulationreagentsofCWM(themixtureofcoalandwater),thetitlecomP0undwassynthesizedbyanoxidativepreparationmethodt2i,whosesynthesisandstructurearedifferentfromthosedescribedbyWangetoft3i.Here,0nlythesynthesisandstructureofthetitlecomP0undarereportedandthestudiesofitsappli-cationareinprogress.2EXPERIMENTAL2.1Preparati0n…     

高配位双环氮氧杂有机锡化合物在二甲亚砜溶剂中的酸性解离常数

本文报道了在DMSO溶剂中利用Bordwell指示剂重迭法测定六种高配位双环氮氧杂有机锡化合物的α-CH的酸性离解常数(pKa)的方法, 并对配合物的结构与其α-CH酸性的关系进行了讨论。     

双环[2，2，1]庚-5-烯-2-甲酰基芳香醛腙的合成和生物活性

合成了七个未见文献报道的双环[2，2，1]庚-5-烯-2-甲酰基芳香醛腙席夫碱 类化合物。用核磁共振氢谱、红外光谱和元素分析对新化合物进行了表征，考察了 它们的生物活性。结果表明某些化合物具有除草作用、抗菌作用和植物生长调节作 用。     

Detection of Tumor Necrosis Factor Gene by Piezoelectric Nucleic Acid Sensor

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｇｅｎｅｄｉａｇｎｏｓｉｓｔｅｃｈｎｏｌｏｇｙ ,ａｌｓｏｃａｌｌｅｄｎｕｃｌｅｉｃａｃｉｄｐｒｏｂｅｔｅｃｈｎｏｌｏｇｙ ,ｈａｓｂｅｃｏｍｅａｎａｔｔｒａｃｔｉｖｅｍｅｔｈｏｄｉｎｔｈｅｆｉｅｌｄｓｏｆｂｉｏｃｈｅｍｉｓｔｒｙａｎｄｃｌｉｎｉｃａｌｍｅｄｉｃｉｎｅ .Ｉｔｉｓｐｒｏｖｅｄｔｏｂｅｃｏｎｖｅｎｉｅｎｔａｎｄｓａｆｅｕｓｉｎｇｎｏｎ ｒａｄｉｏａｃｔｉｖｅｒｅａｇｅｎｔｓｗｉｔｈｅｌｅｃｔｒｏｃｈｅｍｉｃａｌａｎｄｏｐｔｉｃａｌｄｅｔｅｃｔｏｒ.Ｅｓｐｅ ｃ…     

A study of method robustness for arsenic speciation in drinking water samples by anion exchange HPLC-ICP-MS

Regulating arsenic species in drinking waters is a reasonable objective, since the various species have different toxicological impacts. However, developing robust and sensitive speciation methods is mandatory prior to any such regulations. Numerous arsenic speciation publications exist, but the question of robustness or ruggedness for a regulatory method has not been fully explored. The present work illustrates the use of anion exchange chromatography coupled to ICP-MS with a commercially available "speciation kit" option. The mobile phase containing 2 mM NaH(2)PO(4) and 0.2 mM EDTA at pH 6 allowed adequate separation of four As species (As(III), As(V), MMAA, DMAA) in less than 10 min. The analytical performance characteristics studied, including method detection limits (lower than 100 ng L(-1) for all the species evaluated), proved the suitability of the method to fulfill the current regulation. Other parameters evaluated such as laboratory fortified blanks, spiked recoveries, and reproducibility over a certain period of time produced adequate results. The samples analyzed were taken from water utilities in different areas of the United States and were provided by the U.S. EPA. The data suggests the speciation setup performs to U.S. EPA specifications but sample treatment and chemistry are also important factors for achieving good recoveries for samples spiked with As(III) as arsenite and As(V) as arsenate.     

Combined use of high resolution TGA with the isoconversion method: Kinetic analysis of the thermal dehydration of KNbWO6·H2O

In the present study was combined the use of high resolution TGA with the isoconversion method, giving us a suitable methodology for determining the stages that occur during a reaction, and providing further insights about the kinetics of the processes involved. As a model reaction was used the thermal dehydration of KNbWO₆·H₂O. The results shown that the dehydration process is controlled by internal water diffusion (intra-crystallite); with activation energy values between 43 and 36 kJ/mol. This value is consistent with a diffusion mechanism dominated by van der Waals attractions. The estimated kinetic parameters are supported with a structural analysis, that suggest lower dimensionality character for water diffusion due to the specific orientations of 〈1 1 0〉 open channels in the pyrochlore framework. This would explain why the two-dimensional (D2) mechanism appears to be the most probable.     

Examining the role of surfactant packing in phase transformations of periodic templated silica/surfactant composites

In this work, we examine the role of curvature and surfactant packing in controlling the structure of periodic silica/surfactant composites by driving such materials through a transformation from a hexagonal to a lamellar phase. We focus on how the interplay of desired packing and volume constraints dictates the resulting structures. In general, surfactants expand in a complex way upon heating, and this can cause a change in the optimal packing geometry. However, the presence of a rigid silica framework may prevent surfactants from reaching this preferred volume and/or curvature. Real-time in situ X-ray diffraction is used to monitor the structural evolution of these materials heated under hydrothermal treatments. Because the thermal-driven disorder of the surfactant tails drives the phase transition, we examine four types of composites with varying tail density. Ordinarily, composites consist of surfactants with one 20-carbon tail and one positively charged ammonium headgroup. Tail density is varied by replacing a small amount (0-16%) of these single-tail, single-head surfactants with single-tail, double-head 'gemini' surfactants. A greater head--tail ratio indeed produces different results, causing the phase transition to occur at higher temperatures. Using simple geometric models to gain better understanding of our experimental results, we find that, while both unfavorable curvature and limited volume may exist for the surfactants in these composites, the constrained curvature appears to be the dominant effect in driving structural rearrangement.     

Comparison of different derivatization approaches for mercury speciation in biological tissues by gas chromatography/inductively coupled plasma mass spectrometry

A novel interface design for coupling gas chromatography and inductively coupled plasma mass spectrometry (GC/ICP-MS) was used to perform mercury speciation in biological tissues. Three derivatization approaches were optimized and compared for this purpose: anhydrous butylation using a Grignard reagent, aqueous ethylation by means of NaEt(4)B and aqueous propylation with NaPr(4)B. The last reagent was synthesized in the laboratory as it is not commercially available. Detection limits obtained by GC/ICP-MS ranged between 100 and 200 fg (as absolute mass) for methylmercury and between 500 and 600 fg for inorganic mercury using a 1 microl injection. Quantification of methyl- and inorganic mercury was carried out by resorting to aqueous calibration, using ethylmercury as internal standard for both propylation and butylation derivatization techniques. For ethylation procedures, a methylpropylmercury solution was used as internal standard. The absence of transmethylation during sample preparation was checked using a 97% enriched (202)Hg inorganic standard. The accuracy of the three derivatization approaches was evaluated by the analysis of the certified reference material DOLT-2 (dogfish liver) from the National Research Council of Canada and certified for methylmercury, with satisfactory results.     

Thermal Cyclodimerization of Aliphatic Secondary C,N-Dilithioallylamine Derivatives

beta-Nitrogen-functionalized vinylic organolithium compounds derived from secondary aliphatic allylamines have been found to undergo upon heating (reflux of THF) either a dimerization or a regio- and stereoselective cyclodimerization reaction affording diamino 1,4-dienes or cis-2,3-disubstituted 4-methylenepyrrolidines, respectively, according to reaction time. In contrast, the corresponding dianions derived from aromatic allylamines underwent protonation by the solvent under analogous thermal treatment. A mechanism accounting for all these results has been proposed, which involves a spontaneous beta-elimination of lithium hydride and an intramolecular nucleophilic cyclization by addition of a lithium amide to an alkene group as critical steps. In addition, experimental evidence is provided about the formation of 3-lithio-1-aza 1,3-dienes as intermediates in these unusual thermal transformations.     

PHOTOSENSITIVITY OF Ce (Ⅳ) INITIATED METHYL ACRYLATE POLYMERIZATION

The influences of UV light irradiation (313 nm) and diffused daylight on the polymerization of methyl acrylate initiated by the ceric ammonium nitrate without any reducing agent have been studied both in aqueous nitric acid and in pure water. The rate of polymerization was found to be accelerated and the overall activation energy and the induction time were found to be decreased sharply by the UV light irradiation. Under UV light, the rate of polymerization is 8 times as high as the rate in dark. The rate of polymerization was found to attain a maximum with the increase of nitric acid concentration and the rate of polymerization became less sensitive to UV light in the presence of nitric acid whereas the induction period reduced outstandingly. Based on the experimental results, the mechanism is proposed.