离子色谱测定口腔含漱剂中的多种成分

建立了离子色谱法对口腔含漱剂中抗龋剂如氟离子、单氟磷酸根、甘油磷酸根、防腐剂山梨酸、甜味剂糖精以及氯离子、硫酸根、磷酸根等同时测定的方法。采用AS11色谱分析柱和KOH梯度淋洗,抑制电导检测。被测物质的保留时间和峰面积重现性分别小于1.51%和6.02%;被测物的线性相关系数为0.9990~0.9999;加标回收率为89.4%~102.5%。本方法可用于商品化含漱剂和牙棒液体多种组分的同时测定。     

铁酸铋颗粒材料的尺寸调控及其光催化性能研究

采用溶胶-凝胶法,通过改变前驱液中酒石酸加入量制备了不同粒径尺寸的铁酸铋(BiFeO3,BFO)颗粒材料.利用XRD、SEM、UV-Vis、PL、铁电综合测试仪等手段对样品进行表征,探讨分析了颗粒材料尺寸变化对BFO光催化活性的影响及机理.研究表明,产物均为菱形钙钛矿相BFO颗粒态晶体材料;其粒径尺寸随酒石酸加入量的增加而减小;BFO颗粒尺寸减小导致材料BFO可见光吸收阈值波长蓝移,光催化活性提高;在可见光源照射150 min条件下,BFO(粒径尺寸为80 nm)对MB降解效率达到75.7;,其光催化效率大约是BFO(粒径尺寸为600 nm)3倍,这主要是因为较小粒径的BFO具有高的比表面积(6.472 m2/g).     

Feature Enhancement Method of Rolling Bearing Based on K-Adaptive VMD and RBF-Fuzzy Entropy

The complex and harsh working environment of rolling bearings cause the fault characteristics in vibration signal contaminated by the noise, which make fault diagnosis difficult. In this paper, a feature enhancement method of rolling bearing signal based on variational mode decomposition with K determined adaptively (K-adaptive VMD), and radial based function fuzzy entropy (RBF-FuzzyEn), is proposed. Firstly, a phenomenon called abnormal decline of center frequency (ADCF) is defined in order to determine the parameter K of VMD adaptively. Then, the raw signal is separated into K intrinsic mode functions (IMFs). A coefficient En for selecting optimal IMFs is calculated based on the center frequency bands (CFBs) of all IMFs and frequency spectrum for original signal autocorrelation operation. After that, the optimal IMFs of which En are bigger than the threshold are selected to reconstruct signal. Secondly, RBF is introduced as an innovative fuzzy function to enhance the feature discrimination of fuzzy entropy between bearings in different states. A specific way for determination of parameter r in fuzzy function is also presented. Finally, RBF-FuzzyEn is used to extract features of reconstructed signal. Simulation and experiment results show that K-adaptive VMD can effectively reduce the noise and enhance the fault characteristics; RBF-FuzzyEn has strong feature differentiation, superior noise robustness, and low dependence on data length.     

膨胀型阻燃UPR复合材料的阻燃及抑烟性能

将叶蜡石(PYR)与膨胀型阻燃剂[IFR,聚磷酸铵(APP)/季戊四醇(PER)/三聚氰胺(Mel))复配],应用于不饱和聚酯树脂(UPR),得到膨胀型阻燃UPR复合材料。通过氧指数(LOI)、垂直燃烧(UL94)、烟密度等级(SDR)、热分析(DSC-TG)对阻燃复合材料的阻燃、抑烟及热稳定性能进行了研究。结果表明:在该膨胀型复配阻燃体系中,叶蜡石与IFR存在明显的协效作用,在mPYR∶mAPP∶mPER∶mMel=4∶2∶1∶1,复合阻燃剂的含量为40%的情况下,LOI高达36.4,阻燃级别为UL94 V-0级,SDR为62.95,满足国家对B1级电器类热固性塑料的使用要求。     

无外加催化剂条件下的克脑文盖尔缩合反应与溶剂效应的研究

本文报道了无外加催化剂条件下以DMF为溶剂芳香醛与丙二腈或氰基乙酸乙酯进行克脑文盖尔缩合反应, 此法产率较高。讨论了影响溶剂效应的一些因素。     

大孔吸附树脂对肿瘤坏死因子吸附性能的研究

选用NK-110、碳化树脂和MET-10043种大孔吸附树脂,通过对树脂吸附量的测定,吸附动力学曲线和吸附等温线的描述等方法,研究了3种大孔吸附树脂对血浆中TNFα的吸附性能,结果表明NK-110和MET-1004对TNFα的吸附量较高,其中又以MET-1004的吸附速率最快     

Single Unit Cell Bismuth Tungstate Layers Realizing Robust Solar CO2 Reduction to Methanol

Solar CO₂ reduction into hydrocarbons helps to solve the global warming and energy crisis. However, conventional semiconductors usually suffer from low photoactivity and poor photostability. Here, atomically‐thin oxide‐based semiconductors are proposed as excellent platforms to overcome this drawback. As a prototype, single‐unit‐cell Bi₂WO₆ layers are first synthesized by virtue of a lamellar Bi‐oleate intermediate. The single‐unit‐cell thickness allows 3‐times larger CO₂ adsorption capacity and higher photoabsorption than bulk Bi₂WO₆. Also, the increased conductivity, verified by density functional theory calculations and temperature‐dependent resistivities, favors fast carrier transport. The carrier lifetime increased from 14.7 to 83.2 ns, revealed by time‐resolved fluorescence spectroscopy, which accounts for the improved electron‐hole separation efficacy. As a result, the single‐unit‐cell Bi₂WO₆ layers achieve a methanol formation rate of 75 μmol g^?1 h^?1, 125‐times higher than that of bulk Bi₂WO₆. The catalytic activity of the single‐unit‐cell layers proceeds without deactivation even after 2 days. This work will shed light on designing efficient and robust photoreduction CO₂ catalysts.     

电化学法研究蛋白质和茜素红S的相互作用

在pH 4 .2的Britton Robinson缓冲液中 ,茜素红S(ARS)与牛血清白蛋白 (BSA)能形成一种红色的非电活性的超分子复合物。用线性扫描二阶导数极谱法和循环伏安法对该体系进行了研究 ,复合物的形成使ARS的还原峰电流下降 ,峰电流的下降值同所加的BSA浓度在一定范围内呈线性关系。用于BSA的测定 ,在 8.0× 10 -8～ 1.2× 10 -6mol/L范围内呈线性关系 ,检测限为 4 .3× 10 -8mol/L ,对结合反应机理进行初步的探讨     

Linear sweep voltammetric determination of protein based on its interaction with Alizarin Red S

In this paper, the electrochemical behavior of the interaction of Alizarin Red S (ARS) with bovine serum albumin (BSA) was investigated on the hanging mercury drop electrode (HMDE). In the acidic solution (pH 4.2), ARS can be easily reduced on the HMDE and it has a well-defined polarographic wave at −0.29 V (SCE). On addition of BSA or human serum albumin (HAS) into the ARS solution, the reduction peak current of ARS decreases without the movement of the peak potential and the appearance of new peaks. The study shows that a new electrochemically non-active complex is formed via intercalation of ARS with BSA or HSA, which can not be reduced on the Hg electrode. The decrease of reductive peak current of ARS is proportional to BSA and HSA concentration in the range of 2.0–60 and 2.0–40 mg l⁻¹, respectively. The detection limit of BSA and HSA is 1.0-mg l⁻¹. The analytical results of human serum and urine samples by this method were in good agreement with the Coomassie brilliant blue G-250 assay. The binding number and the binding interaction mechanism are also discussed.     

微波促进有机化学反应研究进展

微波促进有机化学反应是一个新的技术。本文介绍了近年来该技术在有机化学领域中的应用情况, 共引用文献68 篇。