Enhanced Specificity of Multiplex Polymerase Chain Reaction via CdTe Quantum Dots

Nanoparticles were recently reported to be able to improve both efficiency and specificity in polymerase chain reaction (PCR). Here, CdTe QDs were introduced into multi-PCR systems. It was found that an appropriate concentration of CdTe QDs could enhance the performance of multi-PCR by reducing the formation of nonspecific products in the complex system, but an excessive amount of CdTe QDs could suppress the PCR. The effects of QDs on PCR can be reversed by increasing the polymerase concentration or by adding bovine serum albumin (BSA). The mechanisms underlying these effects were also discussed. The results indicated that CdTe QDs could be used to optimize the amplification products of the PCR, especially in the multi-PCR system with different primers annealing temperatures, which is of great significance for molecular diagnosis.     

Photoinitiated crosslinking of low density polyethylene I: Reaction and kinetics

The kinetics of the reaction in photocrosslinking of the low density polyethylene-benzophenone-triallyl cyanurate (LDPE-BP-TAC) system was studied by theoretically deriving a kinetic equation and comparing it with the results from crosslinking, extraction and swelling experiments. It was found that the rate of crosslinking is proportional to the square of light intensity. The roles of the crosslinker (TAC) were to capture the excited initiators efficiently to form free radicals and to act as a carrier of the active radicals. The ratio of degradation/ crosslinking was extrapolated to be around 0.28, and compared with 0.44 in the γ-irradiation process for the same material.     

Fe-B非晶态合金中电子转移问题的DFT研究

利用一系列原子簇模型 Fen B2 (n=1～ 4)对 Fe- B非晶态合金的电子结构 ,用 DFT方法进行高水平的量子化学计算 ,结果表明 ,模型体系 Fen B2 (n=1～ 4)中 ,B原子供给 Fe原子电子 ,这与非晶态合金的实验结果一致 ;模型体系不存在类似于 Ni- B非晶态合金中 B- B近距离接触 ,为了比较 ,也选择了单硼原子簇 Fen B(n=1～ 4)模型 ,计算结果与实验不符 ,说明双硼原子簇模型 Fen B2 能在一定程度上反映 Fe- B非晶态合金的局域结构特征。     

超分子体系中光诱导电子转移过程概述

文章主要介绍了超分子光化学反应,即光化学反应应用于超分子体系。详细讨论了在超分子体系下光诱导电子转移过程中所涉及的热力学和动力学原理。同时,在电子转移过程中介绍了Marcus理论以及量子力学理论。     

Electron Transfer Pathways in Cholesterol Synthesis

Cholesterol synthesis in the endoplasmic reticulum requires electron input at multiple steps and utilizes both NADH and NADPH as the electron source. Four enzymes catalyzing five steps in the pathway require electron input: squalene monooxygenase, lanosterol demethylase, sterol 4α‐methyl oxidase, and sterol C5‐desaturase. The electron‐donor proteins for these enzymes include cytochrome P450 reductase and the cytochrome b₅ pathway. Here I review the evidence for electron donor protein requirements with these enzymes, the evidence for additional electron donor pathways, and the effect of deletion of these redox enzymes on cholesterol and lipid metabolism.     

AGET-ATRP制备三元含氟丙烯酸酯乳液及表征

用电子活化再生原子转移自由基聚合(AGET ATRP)方法,在乳液体系下合成了设定化学结构的甲基丙烯酸甲酯(MMA)-丙烯酸丁酯(BA)-甲基丙烯酸三氟乙酯(TFEMA)的三元共聚物;并通过GPC、FTIR及1H-NMR谱表征了共聚物相对分子质量和结构组成;系统研究了聚合条件对含氟丙烯酸酯共聚合物产率的影响.结果表明:含氟丙烯酸酯可以用AGET ATRP体系实现乳液体系的聚合;目标产物符合AGET ATRP的反应机理,所合成的聚合物分子结构可控且相对分子质量分布较窄(PDI=1.42).     

Going with the Electron Flow: Heme Electronic Structure and Electron Transfer in Cytochrome c

Heme is an essential and functionally versatile cofactor. Our understanding of how the environment of a heme in a protein tunes its function has benefited from spectroscopic and functional investigations of heme proteins and their variants with altered heme environments. Two properties of current interest are the conformation of the heme and hydrogen bonding to heme propionates. By combining nuclear magnetic resonance experiments and density functional theory calculations, both of these characteristics have been shown to influence the distribution of the singly occupied molecular orbital on the heme of ferricytochrome c, which affects coupling to redox partners and electron-transfer rates. In addition, heme conformation has been shown to tune reduction potential. These results reveal that subtle variations in heme conformation and in interactions with its propionates can have significant impacts on electron-transfer activity.     

Enhanced Oxygen Reduction Reaction in Nanocrystalline Surface of Samaria‐Doped Ceria via Randomly Distributed Dopants

The randomly distributed dopant effects in nanocrystalline samaria‐doped ceria (SDC) interlayers were investigated by systematically varying the dopant distributions and grain‐boundary densities via post‐annealing process. Electrochemical analysis demonstrates that films having lower annealing or fabrication temperatures exhibit superior surface oxygen kinetics, particularly in the case of oxygen reduction reactions (ORRs). Further investigation through TEM‐EELS shows that the typical segregation of dopants is not significantly present in SDC film deposited via the RF sputtering method, while post‐annealed SDC film shows strong dopant accumulation near the grain boundary. The results indicate that the randomly distributed dopants, in addition to the nano grains, may further enhance surface reactions by providing more preferential reaction sites due to a higher content of defects at the interface.     

非离子型微乳液增敏荷移反应光度法测定饲料中三聚氰胺

OP/异戊醇/甲苯/水非离子型微乳液对电子给体三聚氰胺与π电子受体茜素红的荷移反应有增敏作用,通过实验确定了微乳液增敏荷移反应的分光光度法测定条件。实验结果表明,微乳液增敏三聚氰胺与茜素红生成荷移配合物的最大吸收波长为560 nm,配合物配位比1∶1.3,茜素红用量1.0 m L,温度55℃,加热反应时间40 min,p H 7.0为最佳反应条件,检出限为42.26 mg/L。     

Quantum Entanglement and Electron Correlation in Molecular Systems

We study the relation between quantum entanglement and electron correlation in quantum chemistry calculations. We prove that the Hartree–Fock (HF) wave function does not violate Bell's inequality, and thus is not entangled, whereas the configuration interaction (CI) wave function is entangled since it violates Bell's inequality. Entanglement is related to electron correlation and might be used as an alternative measure of the electron correlation in quantum chemistry calculations. As an example we show the calculations of entanglement for the H₂ molecule and how it correlates with the traditional electron correlation, which is the difference between the exact and the HF energies.     

Electron Transfer Reactions in Biological Nitrogen Fixation

In this review, we summarize our recent efforts toward understanding electron transfer (ET) processes in nitrogenase, the only enzyme capable of reducing dinitrogen to ammonia. We discuss new structural and biochemical perspectives on the role of ATP-dependent interactions between the two components of nitrogenase, Fe-protein (FeP) and MoFe-protein (MoFeP), and how these interactions may regulate interprotein ET and catalysis. We also discuss the implications of our work on FeP- and ATP-independent, photoredox-activated substrate reduction by MoFeP. Elucidating why and how ATP-hydrolysis is needed to control electron and proton flow in nitrogenase is not only a fundamentally important question in biological redox chemistry and energy transduction, but it also holds the key to understanding the intimate mechanism of dinitrogen reduction.     

Efficient Electron Transfer Processes and Enhanced Electrocatalytic Activity of Cobalt(II) Porphyrin Anchored on Graphene Oxide

We investigated the electronic perturbation between graphene oxide and cobalt porphyrin to reveal the origin of the enhanced electrocatalytic activity of a hybrid complex using time-resolved spectroscopic measurements and theoretical calculations. The impulsively generated charge-separated state, GO⁻-(Co^IIAPFP)⁺, undergoes fast charge recombination (<10 ps) between GO⁻ and (Co^IIAPFP)⁺ moieties. This fast charge recombination is directly related to the quick neutralization of (Co^IIAPFP)⁺, which shortens the dead time of inactive Co^IIIAPFP after the electrocatalytic reduction reaction. The fast transformation of inactive Co^IIIAPFP to active Co^IIAPFP is an important factor in the enhanced electrocatalytic activity of the hybrid complex.     

Superexchange-Assisted Through-Bridge Electron Transfer: Electronic and Dynamical Aspects

The effects of electronic structure on bridge-assisted electron transfer are considered. Using static perturbation theory, time-dependent perturbation theory, and direct time-dependent dynamics within generalized tight binding models, we examine the role of energy gaps, relative energetics of donor and acceptor orbitals with hole-type and electron-type superexchange sites, damping and dephasing, and overall energetics in electron transfer. We find that a generalization of the simple McConnell relationship to nonresonant transfer can in fact be made, but that no simple formula describes all limits; this is important in applications to a number of systems, including photosynthetic reaction centers, in which such superexchange occurs. The dynamical studies indicate some important and unexpected phenomena: these include quantum interferences between different pathways, recurrences and oscillations, and competitive effects of hole-type and electron-type superexchange. We suggest that direct dynamical study, as has begun to appear from several laboratories, provides an excellent way to visualize the intermediate state contributions to intramolecular electron transfer processes.     

多变量约束控制在大型FCCU装置中的应用(上)--系统构成及功能概述

国家“九．五”重点科技攻关项目“大型催化裂化装置多变量的约束控制与优化”在石家庄炼油化工股份有限公司一联合车间催化裂化投运成功并通过了国家级技术鉴定,简要介绍了多变量约束控制（ＭＣＣ）与优化系统的构成及功能。     

Iron and Single Electron Transfer: All is in the Ligand

This account describes some advances we have made in the field of iron catalysis. Two types of reactivity have been uncovered. Based on the use of an iron(II) precatalyst in the presence of NaBH₄, the first one consists in a SET which can be useful for the reductive dehalogenation of iodide and bromide derivatives. Switching to the non-innocent bis-iminopyridine ligands promotes a previously undescribed Csp²−H activation reaction leading to biaryl derivatives. First clues into the intricate nature of the mechanism were obtained and suggested that the redox-active bis-iminopyridine ligand acts as an electron reservoir. The resulting buildup of electron density triggers the C−H bond breaking. All these findings are discussed in light of the existing literature and perspectives are given.