醛的自氧化振荡反应

1983年 Jensen 与 Roelofs 等报道了苯甲醛自氧化反应中出现的化学振荡现象。我们还观察到苯甲醛、取代苯甲醛和许多脂肪醛的自氧化振荡反应,实验方法与文献[3]相似。反应在具有电磁搅拌的恒温反应器中进行,以醋酸水溶液(冰醋酸与水的体积比为9∶1)和     

Rasch模型在“化学键”概念教学评价中的应用研究

运用Rasch模型探查高二学生对"化学键"概念的认知情况，运用Conquest软件和Winsteps软件对测试结果进行分析。结果表明：基于Rasch模型编制的测试卷能客观有效地检测学生对"化学键"概念的理解，为一线教师的有效教学提供学情基础。     

Calculations of concentration dependences of chemical shifts for acrylamide in water—DMSO mixed solvent

The lattice model of associated solutions was used to calculate the concentration dependences of the chemical shifts of¹³C magnetic nuclei in the acrylamide molecule in water—DMSO solvent. Each pair of bonds between the acrylamide group containing a magnetic nucleus and the neighboring solvent molecule was assumed to additively contribute to the change in the chemical shift of the nucleus in question. The new approach affords the same accuracy in describing the experimental data at any ratios of the solution components. It was shown that the chemical shifts and the excess heat of mixing of the water—DMSO binary solution can be simultaneously described using the same set of energy parameters of the model. The model makes it possible to employ experimental data on chemical shifts for studying intermolecular interactions in solutions. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1983–1987, October, 1998.     

Adiabatic Potential Energy Surface of the 1,2,3-Trifluorobenzene Cation-Radical

Ab initio study of the adiabatic potential energy surface (PES) for 1,2,3-trifluorobenzene cation-radical was carried out by the ROHF, UHF, MCSCF, MP2, and DFT (B3LYP) methods with the 6-31G* basis set. The PES in question is a pseudorotation surface at all calculation levels. The pseudorotation barrier height does not exceed 3.2 kcal/mol, suggesting a possibility for its manifestations in experimental EPR spectra.     

Reduction of Chemical Reactions in Nitrogen and Nitrogen–Hydrogen Plasma Jets Flowing into Atmospheric Air

The large number of possible chemical reactions represents a severe burdenfor modeling of even relatively simple plasma systems. Reduced sets ofchemical reactions have been obtained for numerical simulations of nitrogenand nitrogen-hydrogen plasma jets flowing into an atmospheric airenvironment. The important or active reactions are determined based on asimplified reduction method. A reaction is considered active if it leadsto higher sensitivities than a specified cutoff sensitivity of 1%. Theactive reactions exert a significant influence on main plasma parameters,such as velocity, temperature, and species concentrations. The sensitivityanalysis for the specified systems shows that two NO reactions, known asZel'dovich reactions (N₂+ONO+N andNO+OO₂+N),⁽¹⁾ are both active in a nitrogenplasma jet. On the other hand, the latter is not active and may be omittedin a nitrogen–hydrogen plasma jet. A nitrogen–hydrogen plasmajet requires contribution of two active charge exchange reactions:N₂+N⁺N⁺ ₂+N andN+H+N+ +H, while only the former is needed in a nitrogen plasmajet. The dissociation reactions are all active in both plasma jets, exceptthe dissociation of OH.     

Chemical conversion of various celluloses to glucose and its derivatives in supercritical water

The supercritical water biomass conversion system was designed and developed in our laboratory. The reaction vessel with cellulose sample was treated with this system at supercritical state of water for a designated period (3–105s) under the conditions of a tin bath temperature of 500°C and pressure of 35MPa. The recovered products of hydrolysates were then analyzed by high performance liquid chromatography. The obtained results indicated that a high amount of glucose and levoglucosan can be achieved from both celluloses I and II for 5–10s supercritical treatment, while that from starch for 3–5s treatment. Although this difference could be due to a difference in the molecular structure between cellulose and starch, a difference between celluloses I and II was not significant. Instead, an accessibility of the water towards cellulose molecules seemed to be significant for their chemical conversion. With the longer treatment, amounts of these compounds observed were decreased due to decomposition. Therefore, it may be concluded that, compared with acid hydrolysis or enzymatic saccharification, cellulose may be hydrolyzed to glucose and its derivatives more or less to the same degree as in corn starch under supercritical state. This finding suggests that the supercritical treatment can overcome the difficulties in hydrolyzing cellulose to glucose, found in the acid hydrolysis or enzymatic saccharification techniques.     

Koexistenzbeziehungen,Darstellung und Eigenschaften ternärer Phasen im System Cu/Mo/O

Coexistence Relations, Preparation and Properties of Ternary Compounds in the System Cu/Mo/O The phase diagram of the ternary system Cu/Mo/O is presented at 773 K. The compounds CuMoO₄, Cu₃Mo₂O₉, Cu₄Mo₅O₁₇, Cu₆Mo₅O₁₈, Cu_4–xMo₃O₁₂, and Cu_xMoO₃ are found to be thermodynamical stable. The homogeneity range of Cu_4–xMo₃O₁₂ runs to x = 0.1–0.2. Single crystals of CuMoO₄ and Cu₃Mo₂O₉ were grown by chemical transport reactions with TeCl₄, Cl₂, HCl, and Br₂ as transport agent. The results were compared with thermochemical calculations. The decomposition of CuMoO₄ and Cu₃Mo₂O₉ was investigated with thermal analysis and decompositon pressure measurements.     

Chemical modification of polymer surfaces: a review

The main approaches that have been taken to chemically modify polymer surfaces are introduced and reviewed. These are wet chemical oxidation, plasma treatment, classical organic chemistry, and attachment of polymer chains. The extent to which each of these approaches can produce the specific modifications desired is discussed, and any unwanted effects that commonly occur are cited. Finally, the need for using several methods of surface analysis in concert to obtain adequate surface characterization is described.     

Cross-linking chemistry and biology: development of multifunctional photoaffinity probes

An efficient method of photoaffinity labeling has been developed based on rationally designed multifunctional photoprobes. Photoaffinity techniques have been used to elucidate the protein structure at the interface of biomolecules by the photochemical labeling of interacting sites. However, the identification of labeled sites within target proteins is often difficult. Novel biotinyl bioprobes bearing a diazirine photophore have contributed significantly to the rapid elucidation of ligand binding sites within proteins, thereby extending conventional photoaffinity methods. This article discusses the synthesis and applications of various photoprobes bearing a biotin, including strategies using cleavable linkages between photophores. The combination of photoaffinity methods with chip technology is also described as a novel entry to rapid affinity-based screening of inhibitors. This review focuses on a rapid and reliable photoaffinity method utilizing diazirine-based multifunctional photoprobes with numerous potential applications in functional proteomics of biomolecular interactions.     

纳米SiO_2颗粒表面修饰的有机分子在介质中的光物理行为研究

利用Sol-Gel方法投篮了单分散性很好的球型二氧化硅纳米颗粒，通过表面化 学修饰法引入了带有荧光发色团的有机分子，通过稳态光物理方法研究了纳米颗粒 表面的有机分子在水、乙醇以及阴、阳离子表面活性剂悬浮液中的光物理行为。实 验表明，纳米颗粒表面有机分子的分散状态是决定其光物理行为的主要因素。这一 结果为设计和开发新型“壳-核”型纳米二氧化硅荧光传感器提供了有用的参考。