丙烯酸乙酯/烯丙基缩水甘油醚共聚物的热可逆共价交联

研究了双环戊二烯基二羧酸及其铵盐对丙烯酸乙酯 /烯丙基缩水甘油醚共聚物的交联反应 ,对比了二者的交联速度 .用DSC评价了它们的热可逆转化行为 .制得了热可逆部分达 79 7%的共价交联环氧型丙烯酸酯橡胶     

Kinetic equation for reversible heterogeneous catalytic reactions

It is demonstrated that when operating far from equilibrium, despite the non-linearity of a complex reaction system, the overall rate of a heterogeneous catalytic reaction is expressed by a classical equation, where the equilibrium constant is determined by the ratio of constants of the forward and reverse reaction, which do not include the lateral interactions in the adsorbed layer.     

Thermally reversible polymer linkages. II. Linear addition polymers

The stepwise addition polymerization reactions of bisazlactones [bis(2-oxazolin-5-one)s] and a variety of 4,4′-bisphenols have been studied for the purpose of making thermally reversible linear polymers. Thus polymerization occurs at or near room temperature, while depolymerization yielding the two monomer species occurs at elevated temperatures. The synthesis of oligomers in solution without the use of catalyst occurs for the reaction of bisazlactones with bisphenols containing an electron-withdrawing moiety between the two phenol groups of the bisphenol. These oligomers regenerate the bisphenol and bisazlactone monomers upon heating to 165–200°C for several hours under dry box conditions. In many cases, these reactions follow the same patterns of reactivity observed in model studies. This chemistry may be useful for forming degradable or recyclable polymers, where shortchain prepolymers, or macromonomers, endcapped with azlactone and phenol moieties could be used to form high molecular weight polymers that are thermoreversible. Such a reaction system might also be used for preventing reactions of bisphenols and/or bisazlactones at low temperatures, with the desired reaction initiated by formation of the reactive species at elevated temperatures. Envisioned uses in this case might be thermally triggered crosslinking or polymerization reactions, or temperature controlled drug release. © 1993 John Wiley & Sons, Inc.     

可逆与不可逆吸附的CO在甲烷化反应中的作用

在自行设计和建立的加压动态分析装置上,研究了工业甲烷化催化剂(Ni/Al_2O_3)上CO的吸附和反应行为。结果表明,在反应温度250℃下催化剂上吸附的CO有可逆吸附和不可逆吸附之分,甲烷的生成是与不可逆吸附的CO作用的结果,而可逆吸附CO则与生成乙烷、丙烷等密切相关。同时发现甲烷化反应过程的发生必须以不可逆吸附的氢存在为前提,且催化剂上不可逆吸附的氢可分为两部分,一部分可以被CO顶出,这部分氢可能起到了诱导CO吸附的作用;另一部分不可逆吸附的氢不能被CO顶出,这部分氢可能是构成催化剂不可缺少的“组分”(或称“促进剂”)。     

Thermally reversible crosslinking of polystyrene via the furan–maleimide Diels–Alder reaction

Mixtures of maleimidomethylated polystyrene with difurfuryl adipate or with furfuryl alcohol-esterified poly[styrene-co-(maleic anhydride)] underwent thermally reversible Diels–Alder crosslinking. Reversal of crosslinking occurred rapidly at 150°C. The instability of the furfuryl group, however, limits the practicability of the reaction. © 1992 John Wiley & Sons, Inc.     

阿霉素的吸附伏安法研究

阿霉素在０．１ｍｏｌ／Ｌ ＨＡｃ－ＮａＡｃ底液，富集电位－０．２０Ｖ，富集时间１２０ｓ，扫速１００ｍＶ／ｓ等条件下，于悬汞电极上产生一灵敏的吸附伏安还原峰，峰电位为－０．４５ＢＶ，峰电流与ＡＤＭ浓度为１．０×１０１０＾－９－４．０×１０＾－７ｍｏｌ／Ｌ范围内呈线性关系，检测限可达５．０×１０＾－１０ｍｏｌ／Ｌ。     

氧化钙脱硫可逆反应过程的研究

在热天平和固定床装置上研究了CaO脱除H2S过程中可逆反应的变化规律。实验结果表明,脱硫过程的最佳温度为Ca(OH) 2分解温度（在二氧化碳不存在情况下）;水蒸气和H2是影响CaO脱硫可逆反应的两个重要因素,提高水蒸气体积分数无论热力学和动力学都有利于逆反应的进行,使得脱硫效率降低,提高H2体积分数可抑制逆反应进行,当H2的体积分数达到一定值时,由多个反应构成的逆反应变为单个反应,高温脱硫精度则由反应(CaO + H2S = CaS + H2O)决定。对通过CaS水蒸气反应实现CaS转化或再生也作了讨论。     

Reversible Enzyme Inhibition–Based Biosensors: Applications and Analytical Improvement Through Diagnostic Inhibition

Abstract

The present review reports the research carried out during past 9 years on biosensors based on reversible enzyme inhibition for determination of drugs, pollutants, and toxic compounds. Applications in food, environmental, and pharmaceutical fields are also reported. Special attention is paid to the optimization of parameters such as enzyme immobilization, substrate concentration, and incubation time. On the basis of the studies reviewed here, it is our view that enzyme inhibition–based biosensors have been shown to be useful analytical tools.     

Electrostatic solvation free energy of amino acid side chain analogs: implications for the validity of electrostatic linear response in water

Electrostatic free energies of solvation for 15 neutral amino acid side chain analogs are computed. We compare three methods of varying computational complexity and accuracy for three force fields: free energy simulations, Poisson-Boltzmann (PB), and linear response approximation (LRA) using AMBER, CHARMM, and OPLS-AA force fields. We find that deviations from simulation start at low charges for solutes. The approximate PB and LRA produce an overestimation of electrostatic solvation free energies for most of molecules studied here. These deviations are remarkably systematic. The variations among force fields are almost as large as the variations found among methods. Our study confirms that success of the approximate methods for electrostatic solvation free energies comes from their ability to evaluate free energy differences accurately.     

Reversible water-swellable chitin gel

A novel, reversible, water-swellable chitin gel has been produced by the carboxymethylation of a dry chitin film. The property of this material is that unlike carboxymethyl-chitin, it takes up water but is not soluble and retains a degree of rigidity even when wet. The degree of swelling depends on the reaction conditions and alkali (sodium or potassium hydroxide) used as a co-reactant during the carboxymethylation. Upon drying, the gel returns to its dry film form. This water uptake and loss is cyclic, which is a desirable property in certain applications and is a tremendous advantage in the handling of this material. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2049–2053, 1997     

Synthesis and Properties of New-type Troponoid Dithio-Crown Ethers

Troponoiddithio-crownethersareakindofnovelcomPounds.Takeshitaetall-'havereportedthesynthesisandmercurophilicpropertiesofthiskindofcompounds.lnthereportedcomPounds,thetWosulfuratomsareattached,partorall,tothetroponeringdirectly.Whetherthedithio-crownethersstillhaveselectiveandreversiblemercurysaltcaptUringabi1itywhenthetWosulfuratomslinktothebenZylic-mpepositionoftroponeringarousedourinterest.Herein,wewishtoreportthatfromthereactionof3,7-dichloromethyl-5-isopropyl-2-methoxytropone4withbis(mer…     

氯化聚乙烯的热可逆共价交联

采用新型热可逆共价交联剂 ,以溶液反应法使氯化聚乙烯 (CPE)交联制得了凝胶量在 80 %左右的共价交联CPE ,研究了不同牌号CPE、催化剂及其用量、反应温度、反应时间及交联剂用量对CPE交联程度的影响 ,并测定了共价交联CPE的热可逆转化特性     

Schiff base as a novel kind of catalyst for reversible complexation‐mediated radical polymerization of methyl methacrylate

Two kinds of Schiff base, N,N′‐dibenzylidene‐1,2‐diaminoethane (NDBE) and N,N′‐disalicylidene‐1,2‐diaminoethane, have been found as efficient organic catalyst for reversible complexation‐mediated radical polymerization (RCMP) of methyl methacrylate (MMA) for the first time. The polymerization results show obvious features of “living”/controlled radical polymerization. Well‐defined and low‐polydispersity polymers (M_w/M_n = 1.20–1.40) are obtained in RCMP of MMA catalyzed by Schiff base at mild temperature (65–80°C). Moreover, Schiff base also exhibits a particularly high reactivity for RCMP of MMA with in situ formed alkyl iodide initiator. The polymer molecular weight and its polydispersity (M_w/M_n is around 1.20) are well controlled even with high monomer conversion. Notably, when the dosage of azo initiator is same as the dosage of iodine, the polymerization could also be realized in the presence of NDBE. The living feature of synthesized polymer is confirmed through the chain extension experiment. In short, Schiff base is a kind of high‐efficient catalyst for RCMP and reverse RCMP of MMA, which can be one of the most powerful and robust techniques for polymer synthesis. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1653–1663     

Preparation and partial characterization of a soluble site-to-site directed enzyme complex composed of alcohol dehydrogenase and lactate dehydrogenase

A soluble, bifunctional enzyme complex has been prepared by crosslinking lactate dehydrogenase and alcohol dehydrogenase with glutaraldehyde. The crosslinking was performed on a solid phase while the active sites of alcohol dehydrogenase and lactate dehydrogenase were held adjacent to one another with the aid of a bis-NAD analog. Subsequently, the enzyme complex was released from the solid phase. The soluble enzyme complex was then purified by using NAD-Sepharose as an affinity adsorbent. Based on gel filtration experiments, the complex was estimated to consist of one of each dehydrogenase. By using a third enzyme, lipoamide dehydrogenase, which competes with lactate dehydrogenase for NADH produced by alcohol dehydrogenase, the effect of site-to-site orientation was studied. It was found that about 83% of the NADH produced by alcohol dehydrogenase was oxidized by site-to-site oriented lactate dehydrogenase compared to a figure of only about 61% obtained in an identical system of separate enzymes. This indicates that given two alternative routes, the preference for the one to lactate dehydrogenase over the one to lipoamide dehydrogenase is enhanced when lactate dehydrogenase and alcohol dehydrogenase are site-to-site oriented.     

Environmentally responsive micelles from polystyrene–poly[bis(potassium carboxylatophenoxy)phosphazene] block copolymers

Amphiphilic diblock copolymers that contained hydrophilic poly[bis(potassium carboxylatophenoxy)phosphazene] segments and hydrophobic polystyrene sections were synthesized via the controlled cationic polymerization of Cl₃P?NSiMe₃ with a polystyrenyl–phosphoranimine as a macromolecular terminator. These block copolymers self‐associated in aqueous media to form micellar structures which were investigated by fluorescence spectroscopy, dynamic light scattering, and transmission electron microscopy. The size and shape of the micelles were not affected by the introduction of different monovalent cations (Li⁺, K⁺, Na⁺, and Cs⁺) into the stable micellar solutions. However, exposure to divalent cations induced intermicellar crosslinking through carboxylate groups, which caused precipitation of the ionically crosslinked aggregates from solution. This micelle‐coupling behavior was reversible: the subsequent addition of monovalent cations caused the redispersion of the polystyrene‐block‐poly[bis(potassium carboxylatophenoxy)phosphazene] (PS–KPCPP) block copolymers into a stable micellar solution. Aqueous micellar solutions of PS–KPCPP copolymers also showed pH‐dependent behavior. These attributes make PS–KPCPP block copolymers suitable for studies of guest retention and release in response to ion charge and pH. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2912–2920, 2005     

Studies of thermokinetics in an adiabatic calorimeter

Thermokinetic research methods for irreversible and reversible reactions in the adiabatic calorimeter are proposed. Four reaction systems, including an endothermic reaction, have been studied with an adiabatic calorimeter and the validity of these methods is verified.     

金属离子Zn2+对精氨酸酶抑制作用的研究

在37℃,pH=9.4,40 mmol.L-1的巴比妥钠-盐酸缓冲体系中,利用微量热法研究了金属离子Zn2+对牛肝精氨酸酶催化L-精氨酸水解反应的影响。实验表明,Zn2+对精氨酸酶催化反应存在着明显抑制作用,其抑制类型为竞争性可逆抑制,并求得抑制常数KI为6.85×10-7mol.L-1。根据其抑制类型和离子半径,推测Zn2+对精氨酸酶的抑制主要是夺取Mn2+的位置,从而使酶失活。     

Thermal and Crystalographic Studies of Mixture La2O3-SrO Prepared Via Reaction in the Solid State

The compound obtained via state solid reaction of the La₂O₃ and SrO oxides and expose the room atmosphere shows the crystallographic data of the compound reported as La₂SrO_x. However, thermogravimetric, differential thermal analysis and XRD with controlled temperature indicated that the stoichiometry of the compound is 2La(OH)₃-SrCO₃, which structural parameters were determined by using the Rietveld method. It was verified that when the compound exposed at room atmosphere, the mixture oxide absorbs H₂O and CO₂ producing hydroxide and carbonate of lanthanum and strontium, respectively, which thermal decomposition occurs by the same steps, producing the La₂O₃-SrO. This revised version was published online in July 2006 with corrections to the Cover Date.     

Nanowire Transistor‐Based Ultrasensitive Virus Detection with Reversible Surface Functionalization

We have applied a reusable silicon nanowire field‐effect transistor (SiNW‐FET) as a biosensor to conduct ultrasensitive detection of H5N2 avian influenza virus (AIV) in very dilute solution. The reversible surface functionalization of SiNW‐FET was made possible using a disulfide linker. In the surface functionalization, 3‐mercaptopropyltrimethoxysilane (MPTMS) was first modified on the SiNW‐FET (referred to as MPTMS/SiNW‐FET), with subsequent dithiothreitol washing to reduce any possible disulfide bonding between the thiol groups of MPTMS. Subsequently, receptor molecules could be immobilized on the MPTMS/SiNW‐FET by the formation of a disulfide bond. The success of the reversible surface functionalization was verified with fluorescence examination and electrical measurements. A surface topograph of the SiNW‐FET biosensor modified with a monoclonal antibody against H5N2 virus (referred to as mAb_H5/SiNW‐FET) after detecting approximately 10^?17 M H5N2 AIVs was scanned by atomic force microscopy to demonstrate that the SiNW‐FET is capable of detecting very few H5N2 AIV particles.