Reproducibility of Turnover Rates in Heterogeneous Metal Catalysis: Compilation of Data and Guidelines for Data Analysis

The combination of turnover rate measurements and surface science techniques allows a firm quantification of rates in heterogeneous catalysis by metals. There are many examples of reactions where the turnover rates from different laboratories are the same. However, there are still problems, as in the isomerization and hydrogenolysis of hydrocarbons over noble metals, where the turnovers rates from different laboratories differ by many orders of magnitude. An explanation for this discrepancy is discussed. Guidelines for experimental work in heterogeneous catalysis that will help to minimize this wide scatter of turnover rates in the future are presented.     

Transport Turnover Rates for Human OCT2 and MATE1 Expressed in Chinese Hamster Ovary Cells

MATE1 (multidrug and toxin extruder 1) and OCT2 (organic cation transporter 2) play critical roles in organic cation excretion by the human kidney. The transporter turnover rate (TOR) is relevant to understanding both their transport mechanisms and interpreting the in vitro–in vivo extrapolation (IVIVE) required for physiologically-based pharmacokinetic (PBPK) modeling. Here, we use a quantitative western blot method to determine TORs for MATE1 and OCT2 proteins expressed in CHO cells. MATE1 and OCT2, each with a C-terminal V-5 epitope tag, were cell surface biotinylated and the amount of cell surface MATE1 and OCT2 protein was quantified by western analysis, using standard curves for the V5 epitope. Cell surface MATE1 and OCT2 protein represented 25% and 24%, respectively, of the total expression of these proteins in CHO cells. The number of cell surface transporters was ~55 fmol cm⁻² for MATE1 and ~510 fmol cm⁻² for OCT2. Dividing these values into the different J_max values for transport of MPP, metformin, and atenolol mediated by MATE1 and OCT2 resulted in calculated TOR values (±SE, n = 4) of 84.0 ± 22.0 s⁻¹ and 2.9 ± 0.6 s⁻¹; metformin, 461.0 ± 121.0 s⁻¹ and 12.6 ± 2.4 s⁻¹; atenolol, 118.0 ± 31.0 s⁻¹, respectively. These values are consistent with the TOR values determined for a variety of exchangers (NHEs), cotransporters (SGLTs, Lac permease), and uniporters (GLUTs, ENTs).     

Phthalic Anhydride from o-Xylene Catalysis: Science and Engineering

Phthalic anhydride is one of the most important products of modem large-scale organic synthesis, and it has a wide application in various branches of chemical industry. It is mostly used (60% of the world production) for preparation plasticizers for PVC. The rapid development of the industrial production of polymeric materials during the last two decades increased the need of phthalic anhydride, which resulted in an increase of its production [1, 2].     

On the role of adsorbed atomic oxygen and CO2 in copper based methanol synthesis catalysts

The reactions of cyclohexane (6.7 kPa) andn-hexane (13.3 kPa) in H₂ (450 kPa) were studied on platinum-rhenium model catalysts in the range 570–740 K. The catalysts were prepared by depositing rhenium on a platinum foil or platinum on a rhenium foil. The catalyst total area was 0.5–1.0 cm². The surfaces were pre-sulfided before reaction and thiophene added to the feed to maintain the surface sulfided under reaction conditions. Sulfur binds with rhenium forming a catalytically inactive rhenium-sulfur compound. As the concentration of rhenium-sulfur on the surface is increased and the platinum ensembles become smaller, only dehydro-genation-hydrogenation activity is observed. However, the catalyst becomes more resistant to deactivation.     

Reactive processing of polymers: Melt grafting of glycidyl methacrylate on ethylene propylene copolymer in the presence of a coagent

Glycidyl methacrylate (GMA) was grafted on ethylene–propylene copolymer during melt processing with peroxide initiation in the presence and absence of a more reactive comonomer (coagent), trimethylolpropane triacrylate (Tris). The characteristics of the grafting systems in terms of the grafting reaction yield and the nature and extent of the competing side reactions were examined. The homopolymers of GMA (Poly‐GMA) and Tris (Poly‐Tris) and the GMA‐Tris copolymer (GMA‐co‐Tris) were synthesized and characterized. In the absence of the coagent, high levels of poly‐GMA, which constituted the major competing reaction, was formed, giving rise to low GMA grafting levels. Further, this grafting system resulted in a high extent of gel formation and polymer crosslinking due to the high levels of peroxide needed to achieve optimum GMA grafting and a consequent large drop in the melt index (increased viscosity) of the polymer. In the presence of the coagent, however, the grafting system required much lower peroxide concentration, by almost an order of magnitude, to achieve the optimum grafting yield. The coagent‐containing GMA‐grafting system has also resulted in a drastic reduction in the extent of all competing reactions, and in particular, the GMA homopolymerization, leading to improved GMA grafting efficiency with no detectable gel or crosslinking. The mechanisms of the grafting reactions, in the presence and absence of Tris, are proposed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1401–1415, 2001     

《材料研究方法》课程教学改革研究

材料研究方法是材料专业本科生需要掌握的一门核心专业课,本文从师资队伍建设、教材建设、教学改革、教学科研互动、培养学生创新能力以及存在的问题等方面总结了近几年材料研究方法课程的教学经验。     

农用市政污泥重金属危害的分析及应对措施

一般认为,污泥中重金属对植物和土壤的潜在危害是阻碍污泥资源化特别是阻碍污泥农用的障碍。通过总结国内外研究结果,认为污泥中重金属的危害性与其形态有关,且不同重金属的不同形态对于不同植物和土壤的危害程度也不可一概而论,因此以污泥中重金属总量判断危害程度是不全面的。研究认为,通过对污泥重金属的预处理,以及对污泥施用后的土壤采取必要的修复措施,可进一步降低污泥重金属对环境的危害。     

材料研究方法研讨型课程建设初探

对材料研究方法研讨型课程建设进行了初步探索,对教学效果进行了总结归纳,这种研讨型课程能明显提高学生学习积极性,有效改善教学效果。     

Use of organosolv lignin in phenol-formaldehyde resins for particleboard production: II. Particleboard production and properties

The objective of this work was to demonstrate the utility of lignin-based resins designed for application as an adhesive in the production of particleboard. Bond qualities of lignin-phenol-formaldehyde resins, phenolated-lignin-formaldehyde resins and commercial phenol-formaldehyde (PF-com) resin were assessed by using an automatic bonding evaluation system, prior to production of particleboards. In order to evaluate the quality of lignin-based resins, particleboards were produced and physical and mechanical properties were investigated. These physical properties included internal bond, modules of rupture and modulus of elasticity. Thickness swell and water absorption properties of particleboards bonded with lignin-based resins were also determined. The lignin-based resins have been reported previously in Part I of this study. The results showed that particleboards bonded with phenolated-lignin formaldehyde resins (up to 30% lignin content) exhibited similar physical and mechanical properties when compared to particleboards bonded with PF-com. The work has indicated that phenolated-lignin formaldehyde resins (up to 30% substitution level) can be used successfully as a wood adhesive for constructing particleboard. The performance of these panels is comparable to those of boards made using PF-com resin.     

The Formation of Epoxy/Metal Interphases: Mechanisms and Their Role in Practical Adhesion

When epoxy/diamine systems are applied onto metallic substrates and cured, an interphase, having chemical, physical, and mechanical properties quite different from bulk polymer is created between the substrate and the polymer. The aim of this work is to understand the interphase formation mechanisms and their role in practical adhesion. Mechanisms were deduced from comparison of behaviors when either epoxy and diamine monomers or epoxydiamine monomer mixtures were applied onto aluminum, titanium, and gold-coated surfaces. Using various analytical techniques (DSC, FTIR, FTIR-RAS, ICP, and POM) we will show both a chemical sorption of the diamine monomers and a partial dissolution of the surface oxide and/or hydroxide metallic layer. Then, metallic ions diffuse through the liquid monomer layer and react with amine groups to form an organo-metallic complex by coordination bonding. When the complex concentration is higher than its solubility limit, these complexes may partially precipitate to form needle-sharp crystals. The liquid part of the organo-metallic complex forms, with the epoxy prepolymer, a new amorphous network having a lower glass transition temperature. This new biphase material can also contain complex crystals which act as short fibers, randomly dispersed in the polymer matrix or oriented in the vicinity of the polymer/metal interface, inducing an increase of the Young's modulus and a decrease of the elongation at break. By using a three-point flexure test, we have determined the effect of the interphase formation on the practical adhesion before and after hydrothermal aging. Results obtained point out that the epoxy/metal interphase significantly affects the initial practical adhesion. However, formation of organo-metallic complexes greatly improve practical adhesion after aging. The created complexes act as corrosion inhibitors.     

Integrating Catalyst and Co‐Catalyst Design in Olefin Polymerization Catalysis: Transferable Dianionic Ligands for the Activation of Late Transition Metal Polymerization Catalysts

Treatment of nickel and palladium α‐diimine catecholate complexes with alkylaluminum catecholates leads to active ethylene polymerization catalysts. Comparison of the catalytic activities achieved with combinations of α‐diimine catecholate or halide complexes as catalyst precursors with different activators (MMAO or alkylaluminum catecholates) reveals that the presence of the catecholate ligand in both catalyst components is beneficial for achieving high activity levels at very low M/Al ratios.     

近几年理科综合高考化学试题分析及复习备考建议

2019年高考化学试题全面落实一核、四层、四翼高考评价体系的要求,以科技期刊、技术专利等资料为素材背景编写试题,以这些最新的科技成果为基础命制的试题有利于开拓学生的科学视野,让学生通过试题情境认识化学学科价值,加强了关键能力的考查,彰显教育改革的鲜明导向。针对2020年高考化学复习备考,将近三年理科综合(新课标全国卷Ⅲ)高考化学试题进行对比分析,由此提出相关的一些复习建议。     

系列阴床比耗偏高的原因分析及处理

平煤蓝天中原甲醇厂除盐水处理碱耗偏高,经过认真分析,采取措施,有效地减少了碱耗偏高的现象。     

Proteins of Unknown Function in the Protein Data Bank (PDB): An Inventory of True Uncharacterized Proteins and Computational Tools for Their Analysis

Proteins of uncharacterized functions form a large part of many of the currently available biological databases and this situation exists even in the Protein Data Bank (PDB). Our analysis of recent PDB data revealed that only 42.53% of PDB entries (1084 coordinate files) that were categorized under “unknown function” are true examples of proteins of unknown function at this point in time. The remainder 1465 entries also annotated as such appear to be able to have their annotations re-assessed, based on the availability of direct functional characterization experiments for the protein itself, or for homologous sequences or structures thus enabling computational function inference.     

Canonical Orderings of Hexagons That: (1) Nearly Meet the Intent of Patterson's Nomenclature Rules and (2) Orient a Molecule for Purposes of Assigning a IUPAC Name

A nomenclature technique developed earlier by the author is expanded to produce an ordering of hexagons that nearly meets the original intent of Patterson's nomenclature rules in organic chemistry for a system of polycyclic aromatic hydrocarbons formed using only benzene modules. The result desired is a simple systematic method which orients a figure formed by the fusion of regular hexagonal rings so that, first, there is a maximum number of rings on a horizontal line and, second, that as many of the remaining rings as possible are above and to the right of this horizontal reference line. In the process of trying to formulate such a system, problems that are inherent in interpreting the intent of Patterson's rules and in pragmatically implementing these rules are examined. Furthermore, a minor modification of the technique produces a canonical orientation of a long molecule which can then be used to formulate the I.U.P.A.C. name for this molecule.     

Correlation between stability of a protein and its dipeptide composition: a novel approach for predicting in vivo stability of a protein from its primary sequence

Statistical analysis of 12 unstable and 32 stable proteins revealedthat there are certain dipeptides, the occurrence of which issignificantly different in the unstable proteins compared withthose in the stable ones. Based on the impact of these dipeptideson the unstable proteins over the stable ones, a weight valueof instability is assigned to each of the dipeptides. For agiven protein the summation of these weight values normalizedto the length of its sequence helps to distinguish between unstableand stable proteins. Results suggest that the in vivo instabilityof proteins is possibly determined by the order of certain aminoacids in its sequence. An attempt is made to correlate metabolicstability of proteins with features of their primary sequencewhere weight values of instability for a protein of known sequencecould thus be used as an index for predicting its stabilitycharacteristics.     

毛竹多元醇液化及液化产物的分析

以多元醇和丙三醇为液化剂,硫酸为催化剂,对毛竹粉进行了液化实验。通过单因素分析和正交实验方法研究竹粉多元醇液化工艺,从节省能源和时间的角度考虑,确定其最佳液化工艺条件为:聚乙二醇400与丙三醇质量比为80∶2 0,在液固质量比3.5∶1、硫酸质量分数3%、反应温度160℃、反应时间90 min时,液化率可达99.32%。所得毛竹粉多元醇液化产物的羟值为28～142.63 mg/g,黏度为100～840 mPa.s。并用红外光谱、GC-MS、凝胶渗透色谱分析了液化产物。     

水厂废水处理投加PAM的分析选择

水厂废水需要寻求高效、无毒、经济的絮凝剂改善污泥水质 ,本文通过实验 ,对多种型号聚丙烯酰胺 (PAM )絮凝剂进行测试 ,对比分析 ,选择了合适型号的絮凝剂     

80万t／a戴维甲醇装置磁力泵首次联运故障的原因分析与对策

中国海洋石油化学股份有限公司新建80万t／a戴维（DAVY）甲醇装置采用大功率磁力泵输送介质（在国内甲醇项目中尚属首次）。介绍了磁力泵的基本原理、结构特点和设备参数;分析了磁力泵在甲醇装置首次水联运过程中出现泵体振动等故障的原因;提出了相应的解决措施并取得较好效果,磁力泵振动值下降到4mm／s。     

利用岩石热解参数S2-Toc图谱分析海拉尔盆地呼和湖凹陷有机质类型及生烃潜力

岩石热解是广泛应用于研究烃源岩有机质成熟度和生烃潜力的一种分析方法。利用热解参数绘制S2-T oc图谱可有效区分研究地层的有机质类型。本文将此方法应用于海拉尔盆地呼和湖凹陷的白垩系各层系烃源岩有机质类型研究,结果表明南屯组二段为II型干酪根,大磨拐河组一段为III型干酪根;南屯组一段干酪根基本无生烃潜力。呼和湖凹陷烃源岩有机质类型为II型和III型,具有较好的油气生烃潜力。