基于Diels-Alder点击反应构建壳聚糖-O-聚乙二醇接枝共聚物

通过Diels-Alder(D-A)反应,合成了具有规整化学结构的接枝共聚物,壳聚糖-O-聚乙二醇(CS-O-PEG).D-A反应所需双烯体(呋喃环)通过糠基硫醇与端甲基丙烯酸酯聚乙二醇之间的巯基-丙烯酸酯(thio-acrylate)反应合成得到;马来酰亚胺基丙酸通过活泼酯法偶联到十二烷基硫酸钠-壳聚糖复合物(SCC)羟基上,从而获得亲双烯体.采用红外光谱(FTIR)和核磁共振(1H-NMR)表征了中间产物与最终产物的结构,并用原位核磁监测D-A反应及其逆反应过程.结果表明,聚乙二醇双烯体可在水介质中温和条件下定量接枝到壳聚糖羟基上,反应具有点击特征;同时,聚乙二醇与壳聚糖之间的连接键在高温下(90℃)可通过D-A逆反应而发生断裂.     

The Preparation and Enzyme Immobilization of Hydrophobic Polysiloxane Supports

Enzymes are versatile biocatalysts and find increasing applications in many areas. The major advantages of using enzymes in biocatalytic transformations are their chemo‐, regio‐, and stereospecificity, as well as the mild reaction conditions that can be used. However, even when an enzyme is identified as being useful for a given reaction, its application is often hampered by its lack of long‐term stability under process conditions, and also by difficulties in recovery and recycling. For ease of application and stabilization purposes, enzymes are often immobilized on solid supports. Among support matrices, hydrophobic biomaterials have been extensively used as supports for enzyme immobilization because the hydrophobic interactions not only can effectively increase the amount of enzyme immobilization, but also exhibit higher activity and retention of activity compared with hydrophilic supports. On the other hand, polysiloxane can evidently increase the amount of enzyme immobilization because of its hydrophobicity and strong affinity with enzyme. Therefore, this research details the first preparation and use of a hydrophobic polysiloxane support for enzyme immobilization in which the structural and functional characteristics of new supports have been investigated by using glucose oxidase (GOD) and a simple Fenton's assay method, and extremely interesting features were revealed. The results showed that the amount of GOD immobilization and the stability of GOD loaded, which are fundamental properties for enzyme separation and purification, can be significantly improved by adsorption. Moreover, the results indicated that hydrophobic polysiloxane supports can effectively increase the enzymatic affinity and durability of GOD, and decrease the rate of GOD desorbed.

     

低损耗有机聚合物光波导的制备及其数字化测量技术

介绍了低损耗有机聚合物光波导的制备工艺, 并采用 Ｃ Ｃ Ｄ 摄像法对波导的传输损耗进行测量。制备了在 ６３２．８ ｎｍ 波长下传输损耗小于 ０．５ ｄ Ｂ／ｃｍ 的有机聚合物光波导     

Thermodynamics and elastic properties of Ta from first-principles calculations

<正>Within the framework of the quasiharmonic approximation,the thermodynamics and elastic properties of Ta, including phonon density of states(DOS),equation of state,linear thermal expansion coefficient,entropy,enthalpy, heat capacity,elastic constants,bulk modulus,shear modulus,Young’s modulus,microhardness,and sound velocity, are studied using the first-principles projector-augmented wave method.The vibrational contribution to Helmholtz free energy is evaluated from the first-principles phonon DOS and the Debye model.The thermal electronic contribution to Helmholtz free energy is estimated from the integration over the electronic DOS.By comparing the experimental results with the calculation results from the first-principles and the Debye model,it is found that the thermodynamic properties of Ta are depicted well by the first-principles.The elastic properties of Ta from the first-principles are consistent with the available experimental data.     

Non-Hermitian Weyl semimetals: Non-Hermitian skin effect and non-Bloch bulk-boundary correspondence

We investigate novel features of three-dimensional non-Hermitian Weyl semimetals,paying special attention to the unconventional bulk-boundary correspondence.We use the non-Bloch Chern numbers as the tool to obtain the topological phase diagram,which is also confirmed by the energy spectra from our numerical results.It is shown that,in sharp contrast to Hermitian systems,the conventional(Bloch)bulk-boundary correspondence breaks down in non-Hermitian topological semimetals,which is caused by the non-Hermitian skin effect.We establish the non-Bloch bulk-boundary correspondence for non-Hermitian Weyl semimetals:the topological edge modes are determined by the non-Bloch Chern number of the bulk bands.Moreover,these topological edge modes can manifest as the unidirectional edge motion,and their signatures are consistent with the non-Bloch bulk-boundary correspondence.Our work establishes the non-Bloch bulk-boundary correspondence for non-Hermitian topological semimetals.     

DL－32／16型多路时间间隔测量仪及其应用

基于模拟内插原理，研制了一种精密多路时间间隔测量仪。该仪器有一个公共起始通道和３２或１６路停止通道，测时范围５０ｎｓ～８２０ｍｓ，分辨力１ｎｓ，精度优于±５ｎｓ。由于采用了内部微处理器，仪器具有内部自检、通道识别、差错指示和测量数据自动显示，打印、处理及掉电保护等功能，并能给出多次测量的平均值、最大值和最小值。实验测量了Ｔ／Γ炸药的爆速和钨合金中的冲击波速度，得到满意的结果。     

Total Synthesis of Bryostatin 8 Using an Organosilane‐Based Strategy

Convergent total synthesis of bryostatin 8 has been accomplished by an organosilane‐based strategy. The C ring is constructed stereoselectively through a geminal bis(silane)‐based [1,5]‐Brook rearrangement, and the B ring through geminal bis(silane)‐based Prins cyclization, thus efficiently joining the northern and southern parts of the molecule.     

新颍Mo-Cu-Se簇合物{MoCu3Se3I}(PPh3)3O·0.5CH2Cl2的合成及晶体结构

新颍Mo-Cu-Se簇合物{MoCu₃Se₃I}(PPh₃)₃O·0.5CH₂Cl₂是由［Et₄N］₂MoSe₄、Cu(PPh₃)₂NO₃和KI在乙腈和二氯甲烷1∶1的混合溶剂中反应所得。晶体属单斜晶系，空间群P2_{1相似文献}   

Scalable Quantum Controlled Gates on Single-Photon Polarization Qubits Assisted by Nitrogen-Vacancy Centers Inside Single-Sided Optical Cavities

International Journal of Theoretical Physics - Quantum logic gates are the foundation of circuit-based quantum computation and quantum simulation. Multi-qubit quantum controlled gates are of vital...     

Novel silver-containing supramolecular frameworks constructed by combination of coordination bonds and supramolecular interactions

The hydrothermal reactions of AgNO(3), 4,4'-bipy, and carboxylate ligands gave rise to three supramolecular architectures, namely [Ag(bipy)].H(2)SIPA.1/2bipy.H(2)O (1), [Ag(bipy)].1/2H(2)btec.H(2)O (2), and [Ag(bipy)](2).H(2)dpstc.2H(2)O (3) (H(3)SIPA = 5-sulfoisophthalic acid, bipy = 4,4'-bipyridine, H(4)btec = 1,2,4,5-benzenetetracarboxylic acid, H(4)dpstc = 3,3',4,4'-tetracarboxydiphenyl sulfone). All complexes are extended from Ag-bipy linear chains by the combination of coordination bonds and supramolecular interactions in two different approaches. Complexes 1 and 3 comprise two-dimensional frameworks. In the two complexes, a one-dimensional ladderlike structure is first formed by the connection of a Ag-bipy chain through hydrogen bonding between a free carboxylate/bipy ligand and weak coordinative interactions between a free carboxylate ligand and silver ion. The ladderlike structure is then extended to a two-dimensional layer architecture by pi...pi interactions between bipy ligands of the Ag-bipy chains. Complex 2 possesses a three-dimensional framework. The free H(2)btec(2)(-) ligands form a two-dimensional layer network by hydrogen-bonding interactions between protonated and deprotonated carboxylate groups; meanwhile, pi.pi interactions between bipy ligands of Ag-bipy chains also result in a two-dimensional layer. The two layers are further connected by weak Ag-O interactions to generate a three-dimensional supramolecular structure.