Amperometric Glucose Biosensor Based on Platinum Nanoparticles Combined Aligned Carbon Nanotubes Electrode

A sensitive amperometric glucose biosensor based on platinum nanoparticles (PtNPs) combined aligned carbon nanotubes (ACNTs) electrode was investigated. PtNPs which can enhance the electrocatalytic activity of the electrode for electrooxidating hydrogen peroxide by enzymatic reaction were electrocrystallized on 4‐aminobenzene monolayer‐grafted ACNTs electrode by potential‐step method. These PtNPs combined ACNTs' (PtNPs/ACNTs) surfaces were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The highly dispersed PtNPs on ACNTs can be obtained. The enzyme electrode exhibits excellent response performance to glucose with linear range from 1×10^?5–7×10^?3 mol L^?1 and fast response time within 5 s. Furthermore, this glucose biosensor also has good reproducibility. It is demonstrated that the PtNPs/ACNTs electrode with high electrocatalytic activity is a suitable basic electrode for preparing enzyme electrodes.     

Simultaneous propane dehydrogenation andco2hydrogenation overCrOx/SiO2catalyst

Summary Single reverse water-gas shift (RWGS) and dehydrogenation of propane with CO₂(DH-CO₂) reactions in the presence and absence of the CrO_x/SiO₂ catalyst have been studied between 673 and 873 K. It was found that the CrO_x/SiO₂ catalyst is active both in the dehydrogenation of propane and in the RWGS reactions. The obtained results suggest that the dehydrogenation of propane to propene in the presence of CO₂on CrO_x/SiO₂can be facilitated by the RWGS reaction.</o:p>     

二硫化碳对机体铜、锌水平的影响

为观察二硫化碳（CS2）对机体铜，锌水平的影响，对某化纤厂35名接触CS2工人和41名非接触工人的血铜，锌值进行调查，比较，并进行了动物染毒实验。SD大鼠吸入CS2浓度分别为5和50mg/m^3，每日5h，每周6d，连续6个月，于染毒2，4，6个月时测定血浆铜，锌值及染毒6个月时肝脏铜，锌含量。结果显示，CS2接触组工人血铜，锌水平较对照组显著降低（P＜0．05）。在CS2染毒6个月时，50mg/m^3 CS2染毒组血浆及肝脏铜水平均较对照组及5mg/m^3 CS2染毒组显著降低（P＜0．05）。可见接触CS2能干扰机体铜，锌代谢，导致体内铜，锌含量减少。     

Insoluble polystyrene-bound quaternary onium salt catalysts for the synthesis of cyclic carbonates by the reaction of oxiranes with carbon dioxide

The addition reaction of oxiranes ( 26a—e ) with carbon dioxide (CO₂) was performed using insoluble polystyrene beads containing pendant quaternary ammonium or phosphonium salts as catalysts under atmospheric pressure. The reaction of 26a—e with CO₂ proceeded smoothly catalyzed by 1–2 mol % of the polymer-supported quaternary onium salts to give the corresponding cyclic carbonates ( 27a—e ) in high yields at 80–90°C. In this reaction system, the catalytic activity of the polymer-supported quaternary onium salts was strongly affected by the following factors: degree of ring substitution (DRS) of the onium salt residues to the polymer, degree of crosslinking (DC) of the polystyrene beads, chain length of the alkylene spacer between the polymer back-bone and the onium salt, hydrophobicity of the alkyl group on the onium salts, and kind of onium salts. That is, the polymer-supported quaternary phosphonium salts with low DRS and DC and with long alkylene spacer chain were found to have higher catalytic activity than low molecualr weight quaternary onium salts. The above polymer-supported catalysts can easily be separated at the end of a reaction by filtration and can be reused for at least seven runs. It was also found that the rate of reaction was proportional to the products of catalyst concentration and oxirane concentration. © 1993 John Wiley & Sons, Inc.     

Classical Valence Similarity in Fullerene Derivatives

Summary.  The generalized Pauling bond order was enumerated in the C₆₀ fullerene cage molecule (truncated icosahedral symmetry). This index measures chemical similarity in fullerene derivatives such as dihydrofullerene (C₆₀H₂), anionized monohydrofullerene (C₆₀H⁻), N-substituted monohydrofullerene (C₅₉NH), the fullerene dimer ((C₆₀)₂), and the dianionic fullerene dimer ((C₆₀)₂ ²⁻). It is also useful in judging the chemical stability of isomers. Received October 9, 2001. Accepted November 9, 2001     

Spectroscopic and Electrochemical Characterization of Cytochrome P450st‐DDAB Films on a Plastic‐Formed Carbon Electrode

We have studied the characterization of thermophilic cytochrome P450 (P450st)‐didodecyldimethylammonium bromide (DDAB) films by using UV‐vis absorption, resonance Raman spectroscopy, and electrochemical methods. The observed Raman spectrum indicated near‐native conformation of the heme iron in DDAB film on the surface of a glass slide, while on the surface of a plastic‐formed carbon (PFC) electrode, the conformation of P450st‐DDAB was very similar to that of heme‐DDAB film, suggesting the release of heme from P450st in DDAB films on PFC electrodes. When NaBr was added as salt to the casting solution, the result of Raman spectrum indicated near‐native conformation of P450st in DDAB film even on the PFC electrode, but no redox potential of P450st which has near native structure was observed. This study suggests the essential experimental conditions when working with heme protein‐DDAB films as, in some cases, heme iron from proteins is released on the surface of the electrode.     

超高比表面炭载钼煤气甲烷化催化剂

以沥青中间相为原料，氢氧化钾直接活化，获得了比表面达２３６３ｍ￣２／ｇ的超高比表面炭分子筛（ＣＭＳ）。分别以ＣＭＳ、ＳｉＯ＿２、活性炭和θ－Ａｌ＿２Ｏ＿３为担体，制备了负载钼催化剂，并研究其加压甲烷化反应性能，发现活性依下面顺序增加：θ－Ａｌ＿２Ｏ＿３＜ＳｉＯ＿２＜活性炭（ＡＣ）＜ＣＭＳ。还分别以钼酸铵和磷钼酸（ＨＰＭｏ）为前驱体，制备了ＣＭＳ负载钼催化剂，并考察了其煤气甲烷化活性，发现不同的催化剂前驱体对催化剂反应活性影响很大。根据产物中ＣＨ＿４／ＣＯ＿２的变化，推测ＣＯ在钼催化剂上的甲烷化反应包括如下两个步骤：（１）３Ｈ＿２＋ＣＯ→ＣＨ＿４＋Ｈ＿２Ｏ，（２）ＣＯ＋Ｈ＿２Ｏ→ＣＯ＿２＋Ｈ＿２。     

氮化铁催化剂的制备及其苯胺催化加氢性能

用α－Ｆｅ２Ｏ３与氨气程序升温还原方法制备出不同温度氮气的氮化铁系列催化剂。通过ＸＲＤ测试对氮化过程中的晶相转变进行了分析。在中压反应装置上考察了氮化铁系列催化剂上苯胺加氢活性以及反应条件对苯胺加氢反应活性的影响。结果表明，在７００℃氮化制香的氮化铁催化剂显示有较高的苯胺加氢活性，在氢压为３．０ＭＰａ，温度为２５０℃，ｎ（Ｈ２）／ｎ（ｏｉｌ）＝１８，液体空速（ＷＨＳＶ）为０．３ｈ＾－１时，该催化剂     

Density of supercritical CO_2-tetrahydrofuran binary mixture and the partial molar volume of the cosolvent

The densities of supercritical CO2-tetrahydrofuran (cosolvent) binary mixture weremeasured at temperatures in range of 308.15 to 323.15 K and at pressure up to 16.5 MPa.The concentrations of tetrahydrofuran were from 0 to 0.57 mol/L.The partial molar volume of tetrahydrofuran was calculated based on the relationship between the density of the mixture and the concentration of the cosolvent.It is observed that the partial molar volume of the cosolvent is negative and the absolute value decreases with increasing pressure and the concentration of the cosolvent.     

Determination of Diffusion Coefficients for Binary Nonelectrolyte Mixtures. A Free-Volume Predictive Approach

A diaphragm cell has been used to measure mutual diffusion coefficients at 25°C for four binary nonelectrolyte mixtures: ethylbenzene + n-hexane, carbon tetrachloride + ethylbenzene, cyclohexane + p-xylene, and 1,2-dichloroethane + cyclohexane. A free-volume predictive approach for binary mutual diffusion coefficients was developed and tested. Only infinite dilution diffusion coefficients, some readily available pure substance data, and UNIFAC group contribution parameters are used in the model. No binary equilibrium thermodynamic information is required. For 73 binary systems with an overall average absolute deviation of 5.2%, it has been shown that the developed method is better than two commonly available reference methods for the prediction of liquid diffusion coefficients.