Zn2+@Polyvinylpyrrolidone and Urushiol Preparation of Nanofibrous Membranes and Their Synergistic Effect

In this study, lacquer is gathered from a lacquer tree and rotary evaporation is used to remove impurities to obtain urushiol. Next, 10 mL of anhydrous ethanol serves as the solvent for blending polyvinylpyrrolidone (PVP) at a specified content (0.7 g and 0.2–0.7 g urushiol) to form an electrospinning solution. Electrospinning is carried out with a voltage of 18 kV to prepare PVP/urushiol nanofibrous membranes. At a ratio of 7/4, the PVP/urushiol nanofibrous membranes are not eroded in 98% sulfuric acid and these membranes also demonstrate a 50–60% antibacterial effect against Staphylococcus aureus and Escherichia coli. Moreover, the antibacterial effect can be boosted to 98% with the incorporation of zinc ions. The results indicate that anhydrous ethanol can remove the sensitization of urushiol from PVP/urushiol membranes. Furthermore, animal test results indicate that when rats are in contact with PVP/urushiol anhydrous ethanol for 48 h, their skins are free from dark brown skin allergy. The presence of PVP eliminates the sensitization of urushiol, and the nanofibrous membranes demonstrate low toxicity. Hence, urushiol is the only natural material that enables PVP to withstand 98% sulfuric acid as well as acquire hydrolyzability, thereby qualify PVP as a medical material.     

稳定同位素标记D_4-罗丹明B的合成及表征

以全氘代邻二甲苯为同位素标记前体,经氧化得到的D_4-邻苯二甲酸与3-羟基-N,N-二乙基苯胺反应生成稳定同位素标记的D_4-罗丹明B,总收率36.9%。目标产物的结构经质谱(MS)、核磁(NMR)等技术手段表征确认,通过高效液相色谱确定化学纯度高于98.0%,同位素氘丰度大于98.0%。将其作为同位素内标试剂用于果汁中罗丹明B的残留检测,在0.05~50 mg/L范围内呈良好的线性关系,其检出限为5μg/kg,回收率为96.4%~103.4%,相对标准偏差(RSD)为1.0%~1.2%,具有很高的灵敏度和准确性。为食品安全领域违禁色素的检测提供了一种可靠实用的方法。     

A mild Cu(I)-catalyzed regioselective diamination of conjugated dienes

This paper describes a novel diamination process that uses CuCl as catalyst and di-tert-butyldiaziridinone as nitrogen source. A wide variety of conjugated dienes and a triene can be effectively diaminated in good yields with generally high regioselectivity under mild reaction conditions.     

Cu(I)-catalyzed intermolecular diamination of activated terminal olefins

This paper describes a novel intermolecular diamination process with CuCl as catalyst and di-tert-butylthiadiaziridine 1,1-dioxide as nitrogen source. A variety of activated terminal olefins can be effectively diaminated in good yields under mild reaction conditions.     

Accelerated direct electrochemistry of hemoglobin based on hemoglobin-carbon nanotube (Hb-CNT) assembly

In this study, we have demonstrated that hemoglobin can be coupled to acid-treated multiwall carbon nanotubes in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and assembled as hemoglobin-carbon nanotube (Hb-CNT) composites. Our observations of the electrochemical studies demonstrate that the electrochemical response of Hb-CNT assembled in the presence of EDC is much higher than that in the absence of EDC. It is evident that the direct electron transfer of hemoglobin could be effectively accelerated in the Hb-CNT assembly by using EDC on a glassy carbon electrode (GCE), and the relative electron transfer rate constant K(s) is found to be 1.02+/-0.05 s(-1). The results of our studies illustrate that the assembly of hemoglobin-multiwall carbon nanotubes using EDC could provide a novel strategy to effectively facilitate the direct electrochemistry of heme-containing proteins, which could be further utilized as a promising biosensor for some specific biological substrate and related biological process.     

色散缓变光纤中宽带调制不稳定性谱的产生

本文报道色散缓变光纤中调制不稳定性效应研究.从非线性Schrodinger方程出发,获得了增益谱与纵向色散变化参量和光纤传输距离的一般关系.研究发现,色散缓变光纤中调制不稳定性的增益谱较常规光纤中的宽得多.调节光纤色散纵向变化参量,可以得到较宽的增益谱.该文的研究结果为光纤中利用调制不稳定性产生超短孤子脉冲提供了理论根据.     

形状不变势结构的研究

在本文中用一种简单的方法系统地研究了形状不变热的结构,导出了迄今为止已知的全部形状不变势,并对于构造更多形状不变势的可能性和途径进行了讨论。     

Selective Determination of Vitamin B2 at Electrochemically Activated Glassy Carbon Electrode

Electrochemically activated glassy carbon electrodes were applied to the preconcentration and electroanalysis of Vitamin B₂ (VB₂) in multivitamin preparation. Voltammetric peak currents showed linear response for VB₂ concentrations in the range between 0.1 to 3.0 M with a large slope of 12.2 AM^-1 and a correlation coefficient of 0.996. The reproducibility of the voltammetric measurements was usually less than 7% RSD for five replicate measurements. Common vitamin and metal species did not interfere the determination.     

A novel electrochemical approach for fabrication of photoluminescent erbium-doped porous silicon

21 /cm³. After this new ECD treatment, PS:Er was found to emit much more intense room-temperature visible photoluminescence than both the porous silicon control and the PS:Er prepared by constant-current ECD. Room-temperature IR photoluminescence around 1.54 μm was observed for the first time without any post-doping annealing. Received: 3 September 1998/Accepted: 9 September 1998     

高效传热管内凝结换热性能及阻力性能的实验研究

本文以ＨＦＣ１３４ａ和ＨＣＦＣ２２为工质对光管及两种不同槽型的强化传热管（ＤＡＥ－２管与ＤＡＥＣ管）的水平管内凝结换热进行了对比实验研究、研究发现,ＤＡＥ－２管平均换热系数比光管提高了１４０％～１７０％,而单位长度阻力损失增加了５０％～１００％,ＤＡＥＣ管平均换热系数比光管提高了１６０％～２００％,同时单位长度阻力损失增加了７０％～１３０％。此外,本文给出了ＤＡＥ－２管和ＤＡＥＣ管平均换热系数及阻力损失的计算关联式,可用于冷凝器设计。