用热分析技术测定碳化硅粉体对聚乙二醇的吸附量

用热分析技术TG-DTA(thermal gravimetric and differential thermal analysis)测定浆料中碳化硅粉体对分散剂聚乙二醇PEG(polyethylene glycol)的吸附量. 结果显示PEG在Ar气氛中411.5 ℃时完全分解; 碳化硅表面分散剂PEG的吸附量随着pH的增大而下降, 在较高pH下大多数分散剂仍存在于溶液中; 分散剂PEG的吸附量通过公式(1)进行计算. 该方法简单方便, 可以应用于测量氧化物或非氧化物吸附紫外-可见分光光度法不能测定的一些有机聚合物分子.     

人工神经网络X射线荧光光谱法测定钢中酸溶铝

建立了一种人工神经网络-X射线荧光光谱法测定钢中酸溶铝的方法，用X射线荧光光谱法测定低合金钢中总铝值，应用所建立的ANN-BP网络模型，输入总铝含量直接预测出酸溶铝含量。同时使用改进的BP算法，避免了神经网络学习中可能产生的麻痹现象。该方法用于钢中酸溶铝的测定，结果满意。     

Chemical synthesis and firefly luciferase produced dehydroluciferyl-coenzyme A

Dehydroluciferyl-coenzyme A (L-CoA) was chemically synthesized and characterized by MS, UV-vis spectrometry and RP-HPLC. The identity of the chemically synthesized compound with the one that was produced by firefly luciferase was confirmed. Moreover, the reversibility of the enzymatic conversion of dehydroluciferin ? dehydroluciferyl-adenylate ? L-CoA was also confirmed. The chemical synthesis of L-CoA, described here, may help the clarification of the activator effect of CoA on luciferase bioluminescent assays, in which the enzyme catalyzed formation of L-CoA and the consequent destruction of L-AMP is one of the possible explanations for that effect.     

Shot noise sets the limit of quantification in electrochemical measurements

Detection of single molecules, particles, and rapid redox events is a challenge of electrochemical investigations and requires either an amplification strategy or significant averaging for the electrochemical current to exceed the noise level. We consider the minimum number of electrons required to reach the limit of quantification in these electrochemical measurements. A survey of the literature indicates that the state-of-the-art limit in current detection for different types of measurements (e.g. voltammetry, single-molecule redox cycling, ion channel recordings of single molecules, metal nanoparticle collision, and phase nucleation) is independent of the nature of the measurement and increases linearly with reciprocal response time, Δt^?1, over ～5 orders of magnitude (from ～10 to ～10⁶ s^?1). We demonstrate that the practical limit of quantification requires cumulative measurement of ～2100 electrons during Δt and is determined by statistics of counting electrons, that is, the shot noise in the current.     

探针反应和FTIR法研究Pt与L型沸石的相互作用

探针反应和ＦＴＩＲ法研究Ｐｔ与Ｌ型沸石的相互作用董家禄,朱建华,须沁华,张婕,刘大壮（南京大学化学系,南京,２１０００８）（郑州工学院化工系,郑州,４５０００２）关键词Ｐｔ／Ｌ沸石,沸石催化剂,异丙醇分解反应,Ｐｔ－载体相互作用Ｐｔ的分散度和电子状态...     

用含偶氮基的聚苯乙烯大分子引发剂合成两亲性嵌段共聚物

采用含偶氮基的聚苯乙烯预聚物（ＰＳ ＡＣＰＣ）作为引发剂，合成了苯乙烯（Ｓｔ）分别与甲基丙烯酸（ＭＡＡ）、甲基丙烯酸（β 羟丙酯）（ＨＰＭＡ）的嵌段共聚物，考察了ＰＳ ＡＣＰＣ引发第二单体的聚合反应行为，以及影响第二单体转化率和均聚物含量、共聚物组成的因素．用溶解性、凝胶渗透色谱（ＧＰＣ）、红外光谱（ＩＲ）、核磁共振（ＮＭＲ）、动态接触角（ＤＣＡ）等表征了嵌段共聚物．     

丙烯酸β-羧乙酯-苯乙烯共聚合的研究

<正> 丙烯酸酯类聚合物是一类性能优良的橡胶、涂料和粘合剂,酯的结构不同可得到性能各异的均聚物和共聚物。 丙烯酸β-羧乙酯(APA)是一种具有多种反应功能的丙烯酸酯单体,结构式为:CH_2=CH—COOCH_2CH_2COOH,其双键可发生加成聚合,制得的大分子带有反应性酯基和羧基侧基,以其制备反应性大分子具有广泛的应用前景。我们研究了丙烯酸β-羧     

The effect of annealing on the subsequent cold crystallization of amorphous poly(ethylene terephthalate)

Amorphous poly(ethylene terephthalate) was annealed at temperatures around the glass transition temperature and then heated up in differential scanning calorimeter at 20 °C min⁻¹. It was found that the annealing favored the subsequent cold crystallization and this effect became stronger with increasing annealing temperature. The experimental results were explained by considering the structural change during the annealing.     

丁酸壳聚糖液晶的临界行为研究

用偏光显微镜法测定了丁酸壳聚糖在四种酸性溶剂中的临界浓度值．发现临界浓度值（ｖ／ｖ％）与溶剂的酸性无关，都是１６％～１７％．在以二氯乙酸为溶剂时，不同丁酰化程度的丁酸壳聚糖有相同的临界浓度．用ＤＳＣ法测定了丁酸壳聚糖／二氯乙酸体系的临界温度，并绘制了相图．结果表明，浓度达６０％（ｗ／ｗ％）后，临界温度基本不再变化，稳定在３９℃左右．     

Selective Determination of Nanogram γ-Globulin in Human Blood Serum by Resonance Light Scattering of Functionalized Nano-PbS

Functionalized nano-PbS has been prepared and characterized. The functionalized nanoparticles have good dispersibility in water. Reaction of functionalized nano-PbS with γ-globulin (γ-IgG) results an enhanced resonance light scattering (RLS) around 385nm.However, when the content of HSA is lower than 0.5μg/ml^-1 the RLS enhancement is very weak and is nonlinear to concentration of HSA. Based on these results, a new direct quantitative determination method for γ-globulin in blood serum samples without separation is established.Under optimal conditions, the enhanced RLS intensity is in proportion to the γ-IgG concentration in the range 10-500ng/mL. The limit of detection is 2.75ng/mL. This method is proved to be very sensitive, rapid, simple and selective for detection of γ-IgG in blood serum.