载流子对聚苯胺可见光催化苄胺氧化性能的影响

使用不同浓度的盐酸对本征态聚苯胺进行再掺杂处理,制备了一系列不同载流子（极化子和双极化子）含量的聚苯胺,通过FTIR、XRD、XPS和EPR等表征分析了极化子和双极化子结构的形成及变化过程,探究了载流子含量对能带结构、苄胺吸附活化、导电性以及光生电子-空穴分离效率的影响,考察了极化子和双极化子结构对聚苯胺光催化苄胺氧化的影响。结果表明：HCl掺杂过程中会有极化子和双极化子结构的形成,极化子和双极化子均能吸附苄胺形成表面复合物,拓展了可见光的吸收范围。极化子结构介导光生电子转移过程,促进光生电子-空穴分离,进而提高光催化苄胺氧化活性,而双极化子的存在对光催化苄胺高效转化不利。     

Unsaturated polyester resin: kinetics of the cross-linking reaction by pulsed NMR

Summary Pulsed NMR at 20 MHz has been used to monitor the time course of the intermediate-final stage of the radical crosslinking reaction (cure of unsaturated polyester-styrene resins.) The measurement of Spin lattice relaxation time T₁ allowed us to follow the hardening process having as a parameter the loss of general mobility of the system at the molecular level.The degree of cure as a function of time, the kinetic constant as well as the activation energy for the crosslinking reaction in isothermal conditions has been evaluated using the semiempirical kinetic equation proposed by Kamal and coworkers. The activation energy was estimated to be 13.6 Kcal per mole of double bonds in the components.     

A possible block in the intermediary metabolism of glucose into proteins and lipids in the brains of undernourished rats

[U-¹⁴C] Glucose or [1-¹⁴C] L-leucine was injected intraperitoneally into 28-day-old undernourished rats and control sibs who were killed 6 hr later. Brain proteins and lipids were extracted and the lipids fractionated by silicic acid column chromatography into cholesterol, glycolipids and phospholipids. The specific activity of labeled carbon derived from [U-¹⁴C] glucose in brain proteins was reduced by 25% in undernourished animals when compared to controls. A similar reduction was seen in the specific activity of brain lipids of undernourished animals: 14% for cholesterol, 21% for phospholipids and 35% for glycolipids. When [1-¹⁴C] l-leucine was used as a direct precursor of brain protein synthesis, the specific activity in the undernourished group was only 5% less than that found for the controls. This was not statistically significant. The results suggest that there may be a block in the intermediary metabolism of glucose in the brains of undernourished rats that reduces the availability of glucose carbon to the precursor pool used for protein and lipid synthesis.     

Observations on changes in lipid composition and lecithin-cholesterol-acyl transferase reaction of bovine plasma induced by heat exposure

A study has been made with steers maintained at 22 C and 35 C on the lipid composition of the plasma, with particular reference to the role and specificity of the lecithin-cholesterol-acyl transferase enzyme in the formation of the cholesteryl esters. Exposure to a temperature of 35 C produced a steady decline in the total lipid concentration of the plasma, which reached a new equilibrium after 7–8 days. The concentrations of the lecithin, free cholesterol and cholesteryl ester fractions in the plasma of the steers at 35 C were reduced to ca. 60% of the corresponding concentrations found in the animals maintained at 22 C. The concentration of 18∶2 circulating in both the cholesteryl ester and lecithin fractions was reduced particularly by exposure to the elevated temperature. No significant change in total blood volume could be detected in the animals between the two environmental temperatures. Incubation of the plasma at 38 C for 20 hr resulted in an increase in the concentrations of the fatty acids contained in the cholesteryl ester and lysolecithin fractions and a decrease in the concentration of the fatty acids contained in the lecithin fraction for the animals at both environmental temperatures. The net esterification of cholesterol by the acyl transferase enzyme in the plasma from the animals at 35 C was very much less than that found in the plasma from the animals at 22 C. Under the conditions of the experiment, the esterification process was shown to have a high specificity for 18∶2. Evidence is available to suggest that the relationship between the acyl transferase activity of the plasma and the polyunsaturated fatty acids of the circulatory lipids may be severely disturbed by high environment temperatures. These results are discussed in relation to several known metabolic effects observed in animals exposed to high environmental temperatures.     

The localization model of rubber elasticity and the deformation of a network formed by cross-linking a strained melt

Summary The localization model of rubber elasticity is applied to the deformation behavior of a network formed by cross-linking a strained melt.     

Urease: A highly biocompatible catalyst for switchable Biginelli reaction and synthesis of 1,4-dihydropyridines from the in situ formed ammonia

Urease is a superior biocompatible catalyst for switching from the Biginelli reaction to urea-based synthesis of 1,4-dihydropyridines in water, where 100% switching occurs at 0.02 g/mL of enzyme. Hantzsch reaction with ammonium acetate (NH₄OAc) is inefficiently catalyzed by urease (70%, 4 h), and heavy metal ions inhibit the urease-catalyzed reactions with urea or NH₄OAc. Promotion of the urea-based Hantzsch reaction by urease and its inhibition with Hg^2 + supports specificity of urease for in situ generation of ammonia, whereas the role of urease in further transformations is not so specific. The features of this enzymatic method are reusability, mild reaction conditions, biocompatibility, generality, and high yield of products.     

The localization model of rubber elasticity and the stress-strain behavior of a network formed by cross-linking a deformed melt

This paper examines the copolymerzation of methyl acrylate (MA) and isobutylene (IB) with a complexed initiating system of AlEtCl₂ and benzoyl peroxide (BPO). The effects of monomer ratio, monomer concentration, initiator composition and polymerization conditions on copolymer composition, degree of alternation, intrinsic viscosity and conversion were studied. An alternating copolymer was obtained when the [IB] / [MA] mole ratio was equal or greater than one.     

The distribution of antimony in the oxide layer formed by potentiostatic oxidation of Pb-Sb alloy

The distribution of antimony within the oxide films on Pb-Sb alloy prepared by potentiostatic oxidation in H₂SO₄ solutions was examined by SIMS. The study of oxide films prepared by applying different potentials for three hours showed that two types of film were obtained depending on whether the potential was more negative or more positive than 1·5 V. Antimony profiles were obtained for films at several stages in the initial growth. It was found that antimony was retained in the oxide film at 1·5 V during both nucleation and two- or three-dimensional growth of PbO₂ and at 1·6 V during the lateral overlaps of three-dimensional centres of PbO₂. Relationships between the antimony distribution profiles and the oxide film growth are discussed.     

A comparison of fenton oxidation and photocatalyst reaction efficiency for humic acid degradation

There have been many studies on the use of photocatalysts as an advanced oxidation process (AOP) to oxidize and degrade organic-based contaminants. This research group has previously reported a production process of Ti based spherical activated carbon and the characteristics of the product. This paper further examines the process of fenton oxidation and the process of Ti-spherical carboneous material (Ti-SCM) photolysis to evaluate their respective advantages and disadvantages. Non-biodegradable humic acid (HA) was chosen for the purpose of the study to observe the degradation. It is demonstrated that fenton oxidation is fast and efficient in a low organic viscous solvent. Ti-SCM is not greatly affected by variation of the pH level and the process is also fast and efficient. Moreover, the process's retention rate of catalysts and its reusability were greater than that of fenton oxidation, which required pH balancing and produced sludge.     

A procedure for the simultaneous determination of lipid and protein in biomembranes and other biological samples

Very small sample sizes frequently become the limiting factor in biochemical and biomembrane studies in which routine quantification of protein and bulk lipids are required. The procedure described here allows the simultaneous determination of protein and lipid without initial, multiple aliquots. The method is based on the quantitative precipitation of proteins from a defined hexane/isopropanol mixture. The liquid phase resulting after decanting and concentrating to dryness can then be used to assay the lipid content directly. Quantitative assay of protein can be achieved after resuspension of the pelleted material by addition of sodium dodecyl sulfate (0.1%) and deoxycholate (1%). The method is also applicable to other types of lipid- and protein-containing samples with a broad range of protein/lipid ratios and lipid compositions, as they occur, for example, in serum lipoproteins.     

An hypothesis for the mechanism of the heme catalyzed lipid oxidation in animal tissues

The catalytic activity of the heme compounds on lipid oxidation in muscle tissues has been reviewed. Evidence from experiments found in the literature, and unpublished studies in this laboratory on meats and fishery products, lead to the conclusion that the ferric heme compounds initiate lipid oxidation, while the ferrous heme compounds are inactive in the absence of preformed peroxides. The latter are decomposed by both types of heme compounds, but by a different mechanism. A comprehensive mechanism of the different catalytic activities of the various heme compounds has been presented, based on both experimental evidence and theoretical considerations.     

1:12系列多金属氧酸盐催化苯甲醛氧化反应的研究

以笨甲醛为原料,过氧化氢作氧化剂,1:12磷钨杂多酸哌啶盐为催化剂,一步反应制得苯甲酸.考察了反应温度、物料比、催化剂用量及反应时间对反应的影响.反应产物抽滤烘干后,通过测熔点来进行分析.采用正交实验法对苯甲酸的合成路线进行优化设计,得出了最优化工艺条件:温度75℃,V(苯甲醛):V(过氧化氢)=1:3.0,m(催化剂)=O.4 g,反应时间5 h,苯甲酸产率达96.7%.     

Activated carbon as catalyst in wet oxidation of phenol: Effect of the oxidation reaction on the catalyst properties and stability

Catalytic wet oxidation (CWO) of phenol has been carried out in a continuous three-phase reactor by using a commercial activated carbon (AC) as catalyst, feeding oxygen as gas phase and an aqueous solution 1000 ppm in phenol to the reactor. A stable catalyst under operation conditions is one of the main difficulties to pass up in the catalytic wet oxidation process, so the stability of the activated carbon with the time on stream (TOS) was investigated. To do this the phenol conversion change was analyzed with TOS and results were contrasted to the change of the physicochemical properties of the AC with the TOS. Gas adsorption/desorption, TPD, XPS and SEM measurements were applied to the AC taken from the reactor after several TOS values. A significant reduction of the micro-pore volume and BET surface area of the catalyst was observed with TOS. However, as reaction proceeded the external surface area and the total amount of oxygen surface group increased. Moreover, regeneration of the initial catalyst properties was done by washing with water saturated in oxygen, at the reaction conditions or by heating in N₂ atmosphere at 450, 700 and 900 °C. The total micro-pore volume and internal surface area of the catalyst were not recovered by the regeneration process, probably due to blockage of the narrow micropores by pyrolytic carbon produced during the first step of the wet oxidation process.     

氧化-偶联光度法测定水中的微量溴离子

介绍了一种测定微量Br-的光度分析方法。在硫-磷混酸介质中,利用KMnO4对Br-选择性氧化,结合羟胺氧化、偶联显色反应,建立的一种分析方法。其检测波长λmax=5 30nm ,吸光系数a =3.2 4×10 3L·(g·cm) -1,适宜的线性检测范围在0 .0 6～0 .2mg·L-1之间。通过对照实验,考察了该测定方法抗共存离子干扰的能力,为其在高矿化度的复杂水体中的应用进行了有意义的尝试。     

催化汽油氧化及萃取脱硫的反应条件研究

催化汽油氧气氧化及萃取脱硫的实验结果表明,随着催化剂用量增加、氧气分压增大、氧化温度提高、氧化时间延长,汽油脱硫率均持续增大,而汽油收率逐渐降低.对脱硫率和收率影响程度从大到小的顺序均为氧化温度＞催化剂用量＞氧气分压＞氧化时间.随着催化剂水溶液重复使用次数增加,汽油脱硫率呈现先降低然后趋于稳定,而汽油收牢先增人后趋于不变.催化汽油经过催化剂用量3.0 g、温度140℃、氧气分压2.0 MPa、时间40 min条件的氧化处理,接着进行水洗及萃取,脱硫率和收率分别为91.57%和67.66%.     

A 31P-NMR study of peroxo species formed during oxidation of cyclohexene with hydrogen peroxide in tri-n-butylphosphate catalyzed by heteropolyacids

In the oxidation of cyclohexene with H₂O₂in monophasic tri-n-butylphosphate (TBP) solution catalyzed by Keggin-type 12-heteropolyacids, i.e., H₃PMo_12-xW _x O₄₀(x=0–12), several peroxo species were observed by ³¹P-NMR spectroscopy in lower field than the original heteropolyacids. Their composition varied regularly with that of the starting catalyst. The P-containing peroxo species formed was deduced as [PM₄O₈(O₂)₈]^3-(M = Mo, W). The peroxo species formed more easily with a decrease in the W content, x of H₃PMo_12-xW_xO₄₀. It was further indicated from the reactivity with cyclohexene and the comparison with catalytic performance that W-rich peroxo species were catalytically more active than Mo-rich peroxo species for the oxidation of cyclohexene in this reaction system.     

硝酸氧化法制草酸过程中各组分的分析检测

研究了硝酸氧化淀粉水解液制备草酸反应液中各组分的检测方法。采用旋光光度计检测葡萄糖含量,结果表明,葡萄糖在溶液中的质量比与溶液的旋光值呈良好的线性关系;采用高效液相色谱分析母液中的草酸含量。其余酸性组分采用碱溶液滴定。     

Halogenated veneers: protein cross-linking and halogenation in the jaws of nereis, a marine polychaete worm

Mineralized tissues are produced by most living organisms for load and impact functions. In contrast, the jaws of the clam worm, Nereis, are hard without mineralization. However, they are peculiarly rich in halogens, which are associated with a variety of post-translationally modified amino acids, many of which are multiply halogenated by chlorine, bromine, and/or iodine. Several of these modified amino acids, namely dibromohistidine, bromoiodohistidine, chloroiodotyrosine, bromoiodotyrosine, chlorodityrosine, chlorotrityrosine, chlorobromotrityrosine, and bromoiodotrityrosine, have not been previously reported. We have found that the distributions of Cl, Br, and I differ: Cl is widespread whereas Br and I, although not colocalized, are concentrated in proximity to the external jaw surfaces. By using nanoindentation, we show that Br and I are unlikely to play a purely mechanical role, but that the local Zn and Cl concentrations and jaw microstructure are the prime determinants of local jaw hardness. Several of the post-translationally modified amino acids are akin to those found in various sclerotized structures of invertebrates, and we propose that they are part of a cross-linked protein casing.     

钒磷氧在醇类氧化反应中的应用研究

综述了近年来国内外研究VPO在醇类氧化反应中的应用进展,重点总结了不同制备方法、制备过程及不同氧源条件下VPO对醇类氧化反应的催化性能影响,探讨了VPO在醇类氧化过程中的反应机理,指出了VPO催化剂研究中存在的挑战以及未来需要突破的方向和目标。