硼酸类荧光受体识别单糖*

糖广泛存在于自然界中,与蛋白质和核酸一起并列构成生命体的三大物质单元。由于糖含有多个羟基,含硼酸基的有机物与二醇间有强烈结合作用,故硼酸基团常用于糖类识别和细胞标记。当荧光体与硼酸基团相连接时即可构建识别糖的荧光传感器。本文按发光团结构进行分类,分为：萘基硼酸类受体（包括对二甲氨基萘硼酸衍生物,N-取代的氨基萘硼酸衍生物,1,8-萘二甲酰亚胺为母体的单硼酸衍生物）、杂环硼酸类受体（包括含氮杂环硼酸衍生物、含硫杂环硼酸衍生物以及含氧杂环硼酸衍生物）、蒽环硼酸类受体、芘环硼酸类受体、紫精硼酸类受体及其它类型的硼酸类受体等,详细评述了自2002年以来含硼酸基团的新型荧光受体在单糖识别研究中的最新进展。     

"一锅法"简便合成一芳基硼酸和二芳基硼酸

本文改进了一芳基硼酸和二芳基硼酸的制备方法. 利用芳卤, 镁屑, 硼酸三正丁酯或三氟化硼乙醚溶液在室温下"一锅"反应简便合成一芳基硼酸和二芳基硼酸, 分离产率为48～80% .     

锡石墨炉原子化机理研究

本文考察了盐酸、硫酸、硝酸、亚硒酸及硼酸中锡的石墨炉原子吸收特性,对锡在不同基体中的原子化过程进行了初步探讨。发现硼酸是石墨炉法测定锡时的一种较好的化学改进剂;1%的硼酸加入可克服一定含量的硫酸与盐酸的干扰。并利用XRD与XPS对硼酸与锡共存时的石墨表面进行了结构与状态分析。提出了硼酸与锡共存时,锡的原子化历程。     

甲醇-丙三醇消解IC法测定高纯硼酸中硫酸根、磷酸氢根、锂、钠、镁、钙

文章通过基体预消除法测定了高纯硼酸中痕量组分硫酸根、磷酸氢根、钠、钾、镁和钙杂质组分。在特制的密闭反应容器中硼酸首先与甲醇生成挥发性的硼酸三甲酯,硼酸三甲酯与丙三醇反应生成不易挥发的多聚硼酸酯,同时释放出甲醇,实现硼酸基体的消除。离子色谱法(IC)测定,各组分的检测限(3σ)分别为硫酸根100 ng/g、磷酸根200 ng/g、锂15 ng/g、钠20 ng/g、钾30 ng/g、镁50 ng/g和钙离子50 ng/g。     

电感耦合等离子体原子发射光谱法测定水晶泥玩具中硼酸和硼酸盐

建立电感耦合等离子体原子发射光谱快速测定水晶泥玩具中硼酸和硼酸盐的分析方法。以纯水为溶剂,采用水浴震荡萃取方式提取样品中硼酸和硼酸盐,外标法定量硼元素,硼酸和硼酸盐的含量以硼酸的形式表示。硼的质量浓度在0.1～5 mg/L范围内与信号强度呈良好的线性关系,线性相关系数(r)为0.999 8,硼酸的检出限为0.007mg/L,定量限为0.021 mg/L。水晶泥玩具样品中硼酸和硼酸盐在3个浓度水平的加标回收率为84.6%～108.4%,测定结果的相对标准偏差小于5%(n=5)。该方法检测快速,适用于水晶泥玩具样品中硼酸和硼酸盐的检测。     

X射线荧光光谱法测定钒铁合金中主次元素含量

用熔融制样法将钒铁合金样品在铂金坩埚中与四硼酸锂和偏硼酸锂熔融,熔体在铂金坩埚中自动成型,用X射线荧光光谱法测定钒铁合金中钒、硅、锰、铝和磷等主次元素含量。经试验求得熔融时,四硼酸锂、混合溶剂(四硼酸锂∶偏硼酸锂=67∶33)和样品的最佳质量比为30比5比1。各元素的检出限在12.4～51.2μg.g-1之间。方法用于标准样品分析,测定值与认定值相符。     

甲醇-丙三醇消解离子色谱 (IC)测定高纯硼酸中硫酸根、磷酸氢根、锂、钠、钾、镁和钙离子

通过基体预消除法测定了高纯硼酸中痕量硫酸根、磷酸氢根、锂、钠、钾、镁和钙离子杂质组分。在特制的密闭反应容器中硼酸首先与甲醇生成易挥发性的硼酸三甲酯,硼酸三甲酯与丙三醇反应生成不易挥发的多聚硼酸酯,同时释放出甲醇,实现硼酸基体的消除。离子色谱法(IC)测定各组分的检测限(3σ)分别为硫酸根100 ng/g、磷酸根200 ng/g、Li+ 15 ng/g、Na+ 20 ng/g、K+ 30 ng/g、Mg2+ 50 ng/g和Ca2+ 50 ng/g。     

Fe(OTf)3催化含有N,O-缩醛结构硼酸酯的合成研究

报道了一种Fe(OTf)₃催化含有N,O-缩醛结构硼酸酯的简便合成方法,反应过程历经路易斯酸催化亚胺鎓与有机硼酸室温进行加成反应,以58%～98%的收率生成了一系列N,O-缩醛硼酸酯化合物.实验结果表明产物具有硼酸酯的性质,可以进行偶联反应.     

硼酸镁晶须增强材料的制备和应用

介绍了硼酸镁晶须增强材料在塑料、金属、合金及复合材料等行业的应用,并对当前硼酸镁晶须的制备方法进行了分析和评述。结合作者等对硼酸镁晶须的研究结果,指出了当前研究中存在的缺点和不足。采用改进的制备工艺能够获得长度为30μm,长径比达30~50的硼酸镁晶须。     

硼酸检测试纸的研制

硼酸可使食品口感爽,目前仍有不少厂家继续在豆、肉、米等制品中掺入硼砂、硼酸,违反国家的有关法律法规。近年来,国内外已报道的硼酸检测方法主要是分光光度法,荧光法、显微结晶法、反向高效液相色谱法、离子排斥色谱法和电感耦合等离子     

Cun、Agn和Aun(n≤9)团簇的静电极化率

The static polarizabilities and polarizability anisotropies of Cun,Agn and Aun (n≤9)clusters have been calculated by the B3LYP density functional method,which is a three parameter mixture of density functional and"exact" Hartree Fock exchange. The calculated results are compared with experimental polarizabilities of sodium clusters. It is shown that the size dependency of the static polarizabilities per atom of Cun,and Agn clusters possesses the same trend as that observed in sodium clusters exception of the Aunclusters while the polarizability of Au atom is much smaller than these of Cu and Ag.The(α-)of Au atom is the smallest and the(α-)per atom of Au approach to the values of Cu from the dimmer to the hexamer. It indicates that in Au clusters the electrons are more strongly attracted by the nuclei because of the more electrons. However,the absolute polarizabilities of the noble mental clusters are considerably smaller than those of the sodium clusters and the electronic structures of the noblemental are much more compact.     

Thermodynamics of dissolving and solvation processes for benzoic acid and the toluic acids in aqueous solution

Experimental data are presented for the solubility in water of benzoic and toluic acids from 5° to 65°C. From the solubility the molality of the monomeric form of the acid is calculated using literature data for both ionization and dimerization of the acid. These data for the monomer combined with data from the literature for vaporization of the solid and ionization in both the gas phase and the aqueous phase yield entropy and enthalpy changes for the solvation of molecular and anionic forms of the acid. A similar procedure is also applied to literature data for the solubility of benzene in water. It is shown that the hydration entropies of the monomeric forms are a linear function of their partial molar volumes. It is concluded that hydration of the undissociated o-toluic acid may be crucial to the increased acidity of that acid compared to benzoic acid.     

Theoretical study of dielectric behavior of microcapsule suspensions with distributed drug release rate

Theoretical consideration is made concerning the dielectric behavior of aqueous suspensions of W/O-type microcapsules containing aqueous electrolyte solutions, especially concerning distribution effects of the electrolyte release rate on the dielectric behavior.It is shown at first that the distribution of the release rate causes electrical conductivity of the capsule interior. Next, it is deduced, in the light of a theory of the interfacial polarization, that the distribution characteristics of the capsule interior's electrical conductivity are closely related to those of the relaxation time for a dielectric relaxation exhibited by the suspensions. Several formulas are derived to describe the relation between the distribution characteristics of the release rate and those of the relaxation time.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

New aspects of migration and flame retardancy in polymer nanocomposites

Annealing of pristine polypropylene blended with the organomontmorillonite (OMMT) at temperatures of 180-340 °C under a stream of nitrogen and of nitrogen-air mixtures is investigated. The oxidative annealing brings about the dispersion of the OMMT in the polypropylene and the formation of a nanocomposite structure. This is evidenced by the increase in the interlayer distance ‘d’ as measured by small angle XRD, with time of annealing and with the weight percent of air. This indicates progressive intercalation of the polymeric matrix into the clay gallery and subsequently exfoliation. The degree of exfoliation is estimated by the extent of migration determined spectroscopically on the surface of the annealed sample. The accumulated clay on the surface due to migration hinders the penetration of the oxygen into the annealing melt as expressed by the decrease in the rate of migration with the increase in the air concentration. This indicates the increase in ageing and storage stability of nanocomposites with increase in the extent of migration. The extent of migration is proportional to the polar carbonyl groups formed on the matrix. The energy of activation of the migration was found to be 37.82 kJ/mol indicating that the rate-determining step of migration is diffusion controlled reaction. The penetration of oxygen into the melt is the first of five steps, followed by oxidation, intercalation, exfoliation and migration. Monitoring the migration with increase in the temperature enables the observation at 275 °C of the transition of the nanocomposite structure to noncolloidal microcomposite. Increasing the annealing temperature above 300 °C brings about a slow, low-temperature combustion and formation of a new kind of char on the surface of the sample.     

INFLUENCE OF THERMAL AND NON-THERMAL EFFECTS OF ULTRASOUND ON ISOTHERMS OF PHENOL ON NKA II RESIN*

1.INTRODUCTIONUltrasoundhasproventobeaveryusefultoolinenhancingthereactionratesinavarietyofreactingsystems.Ithassuccessfullyincreasedtheconversion,improvedtheyield,changedthereactionpathwayand/orinitiatedthereactioninbiological,chemicalandelectrochemicalsystem[1,2].Recentyears,thestudyofultrasonicsandsonochemistryhasexpandedconsiderably.Arapidlygrowingareaisthatof"environmentalsonochemistry",whichmainlydealswithdestructionoforganicsinaqueoussolution.Inaddition,theuseofultrasoundtoenhanced…     

水稻秸秆与PVC塑料共气化过程中钾、钠、氯的迁移行为

采用固定床反应器,结合X射线衍射(XRD)表征和热力学计算研究了水稻秸秆与PVC塑料共气化过程中钾钠氯的迁移和状态变化。结果表明,混合物中氯的释放率与反应温度和PVC塑料的量(氯含量)有关。当反应温度为800~900℃时,PVC的量对混合物中氯元素释放率的影响最为显著;气化温度达900℃时,含PVC 20%(氯含量为11.5%)的水稻秸秆混合物中,氯元素的释放率较纯水稻上升了16.5%。与此同时,氯含量的增加也促进了钾钠在气相中的释放。气化温度为850℃时,当混合物中PVC比例大于20%(氯含量大于11.5%)时,氯对钾钠的气相析出有一定抑制作用;钾钠以KCl和NaCl的形式滞留在固相中,其含量随着混合物中PVC量的升高而降低。     

锌试剂与壳聚糖的结合反应机理的研究

为从分子水平认识多糖分子与小分子之间相互作用的机理,应用光谱法研究了壳聚糖(CTS)与锌试剂(ZCN)的相互作用机理;测得ZCN-CTS复合物吸收光谱出现新的吸收峰所需的临界ZCN/CTS摩尔比为2.67×103, CTS对ZCN的最大结合数为6.93×103,实验值与理论值相吻合,证明了多糖与生物探针相互作用理论模型的可靠性;探讨了ZCN与CTS相互作用产生变色反应的机理,认为其是在ZCN与CTS大分子间发生静电相互作用的基础上,主要由ZCN与CTS大分子间的疏水相互作用所引起.     

Thermophysical Properties of Granules of Instant Drinks in the Process of Structuring

In this article the research of the thermophysical properties of the material depending on its moisture content been represented. The interrelation of various physical properties with the content of moisture in the mass were detected. In addition, their dependence on the quantitative ratio and the properties of structural carcass and pore spaces were proved. The need to consider the volume phase composition of the mixture was justified. A formula to calculate the thermal conductivity coefficient of the product molded from disperse materials was obtained on the basis of Lykov criterion defining the property of drying material and volume phase concentrations. It is proved that the use of volume phase characteristics of disperse systems opens new possibilities for improving the methodologies for determining the those thermophysical properties of dry and wet dispersion materials, allows increasing the reliability results of these definitions, revealing the mechanism of anomalous heat conductivity of wet material.     

TiO2膜光催化剂的改进及表征

提出用粉末-溶胶法制备TiO2薄膜型光催化剂,介绍了粉溶法的制备工艺及改变pH值对催化活性的影响.研究结果表明, 利用粉溶法或添加浓HNO3后制备的TiO2薄膜光催化剂表现出了较高的光催化活性.结合结构表征详细分析了其中的原因.认为粉溶法制备的催化剂表面更粗糙,比表面积增大,膜厚度减小,这些都可能是其催化活性提高的原因.而加酸后膜催化活性提高主要是因为酸性条件下表面几乎没有Ti3+表面态,利于光生电子与光生空穴的分离.