基于表面优先型相变过程构建TiO_2(B)/锐钛矿异相结纳米纤维及其光催化性能（英文）

近年来,随着光催化研究的逐渐深入,人们发现有效的电荷分离往往是提高半导体光催化材料活性的关键步骤.其中,在多晶相半导体材料中构建异相结结构是提高其活性的最有效途径之一.在TiO_2四种稳定晶相中,Ti O2(B)是发现最晚且研究较少的,并且目前对它的研究主要集中于锂离子电池方面,而在光催化领域中研究较少.然而,该材料特殊的晶相结构带来的各向异性和较大的比表面积都表明其在光催化领域同样具有潜在应用前景.本文通过三步合成法,包括水热过程、离子交换、退火过程,研究了TiO_2(B)向锐钛矿转变的相变过程,同时构建了具有TiO_2(B)/锐钛矿异相结结构的纳米线.在材料退火过程中,通过X射线衍射(XRD)和表面灵敏的紫外拉曼光谱(UV-Raman)分别监测了样品体相和表面相的晶相结构变化过程.发现了XRD与UV-Raman结果的不同步性.同时,通过对样品扫描电镜和透射电镜的形貌表征可知,TiO_2(B)纳米线在退火过程中部分结构发生坍塌,且逐渐转化成锐钛矿相,而相变过程很可能首先发生在坍塌结构处.高分辨电镜结果表明,纳米线中同时存在着TiO_2(B)结构和锐钛矿结构,并形成很好的异相结.根据相结构变化和形貌观察结果,我们推测TiO_2(B)向锐钛矿转变过程为表面优先型的相变过程,即材料表面相先于体相先发生相变过程,由此得到的材料表面相含有较多的锐钛矿,而体相中含有较多的TiO_2(B).为了验证构建的异相结材料的光催化活性,采用光催化产氢和降解污染物双重反应对样品进行了表征.结果发现,单独的TiO_2(B)材料活性较锐钛矿材料相差较多,但其混相结构能较大幅度地提高光催化活性.其中,通过逐渐退火过程形成的体相为24%的TiO_2(B)、表面为100%的锐钛矿相的催化剂活性最高,其产氢活性可达4.82 mmol/(h?g),降解污染物反应速率常数为0.0402 min~(-1).采用光电流测试、电化学阻抗和荧光光谱表征了材料在光催化过程中的载流子动力学行为.结果表明,最优活性的催化剂中体相的异相结结构对光生电荷的分离、传输都起到良好地促进作用,而表面的锐钛矿相主要负责高活性的表面反应,二者共同对高活性的光催化反应起到推动作用.     

双丙酮-D-甘露糖醇—硼酸络合酸手性毛细管电泳法分离盐酸莱克多巴胺立体异构体

采用手性多羟基化合物—硼酸络合酸为手性选择剂,建立了分离盐酸莱克多巴胺4个立体异构体的手性毛细管电泳(NACE)方法.实验考察了手性选择剂的种类、浓度和三乙胺浓度对手性分离效果的影响.结果表明,双丙酮-D-甘露糖醇—硼酸络合酸手性选择剂的分离效果最好,优化的缓冲溶液组成为含100 mmol/L双丙酮-D-甘露糖醇、10...     

并行帧同步扰码器的扩充比特设计法

在递推公式并行扰码处理方法的基础上,提出了一种使用扩充比特进行帧同步扰码器设计的新方法.利用扰码序列的周期性原理,从理论上证明了并行扰码复杂度与扰码生成多项式的具体形式无关.无需计算并行扰码递推公式,简化了解扰码器的设计过程,只须用深度与生成多项式阶数相关的存储器和少量的读写控制逻辑就可以实现对任意字宽解扰码处理.该方法在FPGA设计与实现中得到了验证,实现了高效和低复杂度.采用该方法的处理模块已在光通信传输网前端处理系统中得到了应用.     

Development and Optimization of Chitosan Nanoparticle-Based Intranasal Vaccine Carrier

Chitosan is a natural polysaccharide, mainly derived from the shell of marine organisms. At present, chitosan has been widely used in the field of biomedicine due to its special characteristics of low toxicity, biocompatibility, biodegradation and low immunogenicity. Chitosan nanoparticles can be easily prepared. Chitosan nanoparticles with positive charge can enhance the adhesion of antigens in nasal mucosa and promote its absorption, which is expected to be used for intranasal vaccine delivery. In this study, we prepared chitosan nanoparticles by a gelation method, and modified the chitosan nanoparticles with mannose by hybridization. Bovine serum albumin (BSA) was used as the model antigen for development of an intranasal vaccine. The preparation technology of the chitosan nanoparticle-based intranasal vaccine delivery system was optimized by design of experiment (DoE). The DoE results showed that mannose-modified chitosan nanoparticles (Man-BSA-CS-NPs) had high modification tolerance and the mean particle size and the surface charge with optimized Man-BSA-CS-NPs were 156 nm and +33.5 mV. FTIR and DSC results confirmed the presence of Man in Man-BSA-CS-NPs. The BSA released from Man-BSA-CS-NPs had no irreversible aggregation or degradation. In addition, the analysis of fluorescence spectroscopy of BSA confirmed an appropriate binding constant between CS and BSA in this study, which could improve the stability of BSA. The cell study in vitro demonstrated the low toxicity and biocompatibility of Man-BSA-CS-NPs. Confocal results showed that the Man-modified BSA-FITC-CS-NPs promote the endocytosis and internalization of BSA-FITC in DC2.4 cells. In vivo studies of mice, Man-BSA-CS-NPs intranasally immunized showed a significantly improvement of BSA-specific serum IgG response and the highest level of BSA-specific IgA expression in nasal lavage fluid. Overall, our study provides a promising method to modify BSA-loaded CS-NPs with mannose, which is worthy of further study.     

静态水热晶化法高效合成MCM-22分子筛

 采用静态水热晶化法，在Na2O－Al2O3－SiO2－HMI－H2O（HMI：六亚甲基亚胺）体系中，在HMI／SiO2摩尔比为0．09，H2O／SiO2摩尔比为12，晶化时间为60～80h的条件下，合成了MCM－22分子筛．利用固体硅胶表面的吸附性能提高模板剂的局部浓度，从而实现了分子筛的高效合成．对合成条件的研究结果表明，以比表面积（486m2／g）大、反应性能好的硅胶为硅源是静态水热晶化法高效合成MCM－22分子筛的关键，而成胶老化方式对MCM－22分子筛的晶化影响不大．产物的晶相和转晶的类型取决于合成凝胶的初始硅铝比．当SiO2／Al2O3摩尔比＝18～80时可以合成出MCM－22，当SiO2／Al2O3＝13～17时可以合成出MCM－49．硅铝比较低（如SiO2／Al2O3＝20）时，MCM－22分子筛易转晶为MOR分子筛，而在硅铝比较高（如SiO2／Al2O3＝50）时，可转晶为ZSM－5分子筛．     

Paramagnetic Conducting Metal–Organic Frameworks with Three-Dimensional Structure

3D well-crystallized metal–organic frameworks (MOFs), M-THBQ (M=Fe, Co, Mn, THBQ=tetrahydroxybenzoquinone), are synthesized and characterized. Their structures are determined as cubic cell in the group of Pm from powder X-ray diffraction data, and their properties of electronic, magnetic and spectroscopic are also investigated. They are all semiconductors, and Fe-THBQ exhibits the air-stable n-type thermoelectric characteristic as its Seebeck coefficient reaches −130 μV K⁻¹, and the electrical conductivity is 2.7×10⁻⁴ S cm⁻¹ at 300 K. Additional, M-THBQ are paramagnetic, and the value of Weiss constant of Fe-THBQ is −219.37 K, indicating the existence of robust intramolecular antiferromagnetic exchanges. Meanwhile, they display strong absorption bands in the range of 220 to 1000 nm, suggest M-THBQ could have the potential to become photoabsorbers, and Fe-THBQ exhibits a narrow band gap of 0.63 eV according to the ultraviolet absorption edge spectrum.     

Surface Modification of Multiple Bioactive Peptides to Improve Endothelialization of Vascular Grafts

Endothelialization is an effective approach to prevent thrombus formation and enhance vascular graft survival. Surface modification of biomolecules has been proved to be effective in regulating endothelial cell behaviors. In this study, several peptides including YIGSR, RGD, and REDV sequences are covalently immobilized on the surface of electrospun silk fibroin scaffolds and the effects of combined application of these peptides on cell behaviors are studied. The results show that, compared with the scaffolds modified with single peptides, the scaffolds modified with dual peptides (YIGSR+RGD) could significantly enhance the proliferation of human umbilical vein endothelial cells (HUVECs). However, the combination of REDV+RGD or YIGSR+REDV does not promote the adhesion or proliferation of HUVECs. Notably, YIGSR‐modified scaffolds improved HUVEC migration significantly in comparison to REDV‐ or RGD‐modified groups. Moreover, its combination with either of these two peptides also presents excellent effect on cell migration. Thus, all the data suggest that the combined application of peptides might be a promising method to enhance the endothelialization of small‐diameter vascular grafts.     

高镍三元正极材料的表面包覆策略

锂离子电池(LIBs)因具有更高的重量/体积能量密度、 更长的使用寿命、 更低的自放电率等优点而逐渐被广泛应用. 相比于已经广泛使用的钴酸锂和磷酸铁锂等正极材料, 高镍三元正极材料Li[Ni_1-x-yCo_xMn_y]O₂(NCM)以其高电压和高容量等优点, 逐渐成为下一代高能锂离子电池的首选正极材料之一. 尽管高镍NCM正极材料具有上述优点, 但在进一步的实际应用前还需解决其循环稳定性、 倍率性能和安全性等问题, 这些问题主要源于NCM材料本身的晶体结构不稳定、 正极-电解液间界面副反应及高界面电阻等. 针对这些问题, 目前对高镍NCM正极电化学性能优化的大量研究都与电极-电解液界面有关, 如何通过改善界面稳定性、 增加离子在固液界面的迁移率、 抑制界面副反应、 提高正极材料的稳定性进而改善电池性能成为了关注焦点. 本文总结了目前对于其电化学性能衰减的机理解释, 分类概括了包括电化学惰性包覆锂、 残积物清除剂包覆和锂离子良导体包覆等对于高镍NCM正极材料的颗粒表面包覆策略, 简述了一些新兴的包覆策略, 并对高镍NCM正极材料的发展方向和前景提出了展望.     

Over 10 000 Peptide Identifications from the HeLa Proteome by Using Single‐Shot Capillary Zone Electrophoresis Combined with Tandem Mass Spectrometry

Capillary zone electrophoresis (CZE)–tandem mass spectrometry (MS/MS) has recently attracted attention as a tool for shotgun proteomics. However, its performance for this analysis has so far fallen far below that of reversed‐phase liquid chromatography (RPLC)–MS/MS. The use of a CZE method with a wide separation window (up to 90 min) and high peak capacity (ca. 300) is reported. This method was coupled to an Orbitrap Fusion mass spectrometer through an electrokinetically pumped sheath‐flow interface for the analysis of complex proteome digests. Single‐shot CZE–MS/MS lead to the identification of over 10 000 peptides and 2100 proteins from a HeLa cell proteome digest in approximately 100 min. This performance is nearly an order of magnitude better than earlier CZE studies and is within a factor of two to four of the state‐of‐the‐art nano ultrahigh‐pressure LC system.