Electrochemically deposited boronate affinity extracting phase for covalent solid phase microextraction of cis-diol biomolecules

A new format of solid phase microextraction (SPME), boronate affinity SPME, was proposed for the first time for covalent extraction of cis-diol containing biomolecules. This new SPME format is based on the reversible complex formation between boronic acids and 1,2- and 1,3-cis-diols. The complex formation and dissociation can be facilely controlled by changing pH. An extracting phase of poly-3-aminophenylboronate (polyAPBA) electrochemically deposited on a metal wire was employed to demonstrate the concept of this new methodology. Catechol and riboflavin were used as the test analytes, and the SPME extraction was combined off-line with high-performance liquid chromatographic (HPLC) separation followed by UV absorbance or fluorescence detection. Fundamental aspects, such as selectivity, extraction/desorption equilibrium, linearity, effect of competing compounds, reproducibility and life-time, were first investigated. Then the developed method was applied to beer samples since the content of riboflavin plays an important role in the flavor stability of beverages. Excellent performance of the SPME fibers was observed for both standard and real samples. Particularly, the expected excellent features of the polyAPBA extracting phase were experimentally verified, which include specific selectivity, eliminated matrix effect and manipulable capture/release. The new methodology of SPME can be a promising tool since a lot of 1,2- and 1,3-cis-diol-containing compounds are of great biological importance.     

闭式硼烷[B10H10]2－的反应性及其衍生物的应用研究进展

多面体硼烷化合物以其独特的结构、成键和多方面的潜在应用价值而被广泛研究. 综述了近20年来闭式(closo)硼烷[B10H10]2－的反应性(笼上氢取代、开笼-重排、开笼-金属插入等类型)及其衍生物的应用(硼中子俘获肿瘤治疗、放射性同位素萃取分离、新型材料、超分子化学等方面)研究进展.     

Phylogenetic inference from binary sequences reduced by primary DNA sequences

Given a bi-classification of nucleotides, we can obtain a reduced binary sequence of a primary DNA sequence. This binary sequence will undoubtedly retain some biological information and lose the rest. Here we want to know what kind of and how much biological information an individual binary sequence carries. Three classifications of nucleotides are explored in the present article. Phylogenetic trees are built from these binary sequences by the Neighbor-Joining (NJ) method, with evolutionary distance evaluated on the basis of a symbolic sequence complexity. We find that, for all data sets studied, binary sequences reduced by the purine/pyrimidine classification give reliable phylogeny (almost the same as that from the primary sequences), while the other two result in discrepancies at different levels. Some possible reasons and a simple model of sequence evolutionary are introduced to interpret this phenomenon.     

朝鲜淫羊藿的色谱指纹图谱及液相色谱/电喷雾串联质谱分析

建立了长白山区朝鲜淫羊藿药材的高效液相色谱指纹图谱的分析方法. 确定了18批朝鲜淫羊藿药材的13个共有峰, 该指纹图谱的精密度、稳定性和重现性的相对标准偏差均低于3.0%. 结合液相色谱/电喷雾串联质谱对特征峰进行了结构确认, 并根据电喷雾串联质谱数据推测了13个特征化合物的结构. 结果表明采用高效液相色谱与质谱联用技术对朝鲜淫羊藿色谱指纹图谱中的特征峰进行结构确认, 使其色谱指纹图谱的特征性更强, 更适合于药材质量的鉴别与评价.     

PEG-醛修饰胰岛素产物的构象、纤维化和抗酶解能力

通过圆二色谱分析研究了PEG-醛修饰胰岛素产物在溶液中的构象变化,采用加速振荡实验研究了PEG化对胰岛素纤维化的影响,以体外酶解实验考察了PEG-醛修饰胰岛素产物的抗酶解能力.结果表明,经PEG-醛修饰可以减少胰岛素单体的自缔合,提高胰岛素在溶液中的稳定性,抑制胰蛋白酶和糜蛋白酶对胰岛素的降解.     

Closedness of ranges of upper-triangular operators

In this paper, the closedness of ranges and Kato non-singularity of upper triangular operator matrices are investigated.     

SnO2 meso-scale tubes: One-step,room temperature electrodeposition synthesis and kinetic investigation for lithium storage

SnO₂ meso-scale tubes were synthesized by anodic electrochemical deposition under ambient conditions. Controlled self-bubbling O₂ acted as both the template and the oxidizing agent for obtaining SnO₂ tube structures at the interface of the gas (O₂) and the liquid (electrolyte). Electrochemical testing showed that the meso-scale tubes have higher discharge capacity and better rate capability than the “microbowls” produced by varying the deposition conditions. From the Arrhenius plot, the apparent activation energies were calculated to be 58.4 and 90.1 kJ mol^?1 for the meso-scale tubes and the microbowls, respectively, indicating that the meso-scale structure allows shorter diffusion routes for the lithium ions or for easier interaction with lithium.     

Crossover of critical behavior in La0.7Ca0.3Mn1−xTixO3

Critical behavior of Ti-doped La_0.7Ca_0.3MnO₃ ceramics are studied using magnetization methods. The results show that the paramagnetic–ferromagnetic transition is first order for the undoped sample, then for low-doping samples the mean-field model is suitable, and finally a 3D Heisenberg model is satisfied for higher doping samples. These findings demonstrate that the critical behavior of the magnetic transition for manganites is sensitive to Mn-site doping.     

Texture analysis of RF-sputtered CeO2 buffer layers and superconducting MOD-YBCO films

CeO₂ buffer layers were deposited on YSZ single-crystal substrates using an RF-sputtering method. The development of crystalline textures of sputtered CeO₂ films at different sputtering pressure and their effects on YBCO films, deposited by Metal Organic Deposition (MOD), were investigated. Both CeO₂ and subsequent YBCO films grew well epitaxially. The relative XRD peak intensities of CeO₂ (2 0 0) to substrate YSZ (2 0 0) increased with deposition pressure in the range of 3–5 mTorr and were inversely proportional to the θ–2θ scan FWHM values of CeO₂ (2 0 0). Also, the reaction layers of BaCeO₃ were thicker in the samples with lower CeO₂ (2 0 0) intensities and poor out-of-plane alignment when CeO₂ were deposited at the lower pressure of 3.3 mTorr. It is noted, however, that the superconducting layer grew well epitaxially on these BaCeO₃ layers, possibly due to the epitaxial relation between CeO₂ and YBCO. The superconducting critical currents of MOD-YBCO films showed an increasing tendency as both the Δ2θ (CeO₂) and BaCeO₃ peak intensities decreased.     

硬球势中相对论费米气体的热力学性质

用量子统计与数值模拟相结合的方法,在广义外势中相对论费米系统的热力学量的基础上,研究硬球势中相对论费米气体的热力学性质.得到了考虑相对论效应时系统的内能和热容量的解析表达式,分析了相对论效应对内能和热容量的影响.研究表明:与非相对论比较,相对论费米气体的内能和热容量更高;相对论特征量越大,热容量的转折温度越低;随着温度的升高,特征量越大,内能就越大.