波导短程透镜的实验研究

波导透镜是集成光路〔IO〕中的最基本元件,它在IO中的作用类似体光学光路中的透镜.IO光信号处理系统如集成光学声光频谱分析器、导波声光卷积器、相关器、调频脉冲压缩器和矩阵乘法器等.系统中都需要用波导透镜.波导短程透镜较其它形式的波导透镜具有孔径大、旋转对称、无色差和插入损耗小的特点,所以特别引人注意.     

A Highly Efficient Dimeric Manganese‐Catalyzed Selective Hydroarylation of Internal Alkynes

We have developed a general and site‐predictable manganese‐catalyzed hydroarylation of internal alkynes in the presence of water, under an air atmosphere without the involvement of ligand. The unique catalytic feature of this reaction is highlighted by comparison with other widely used transition metal catalysts including palladium, rhodium, nickel, or copper. The simple operation, high efficiency and excellent functional group compatibility make this protocol practical for more than 90 structurally diverse internal alkynes, overcoming the influence of both electronic and steric effect of alkynes. Its exclusive regio‐ and chemoselectivity originates from the unique reactivity of the manganese‐based catalyst towards an inherent double controlled strategy of sterically hindered propargyl alcohols without the installing of external directing groups. Its synthetic robustness and practicality have been illustrated by the concise synthesis of bervastatin, a hypolipidemic drug, and late‐stage modification of complex alkynes with precise regioselectivity.     

Enantioselective Recognition of Tartaric Acids with Ethynylated Carbazole-Based Chiral Bisboronic Acid Chemosensors with Improved Response at Acidic pH

Chiral bisboronic acid chemosensors based on ethynylated carbazole were prepared. The chiral chemosensors show red-shifted emission than the chemosensors with unsubstituted carbazole fluorophore. a-PET effect was found for the chemosensors, which is different from our previous observation of the d-PET effect for boronic acid chemosensors based on carbazole. Enantioselective recognition of tartaric acids was implicated with these chemosensors. Consecutive fluorescence emission enhancement/diminishment were observed with increasing the concentration of the tartaric acids, which is tentatively assigned to the transition of the binding stoichiometry from 1:1 binding to 1:2 binding. In particularly interesting is the improved fluorescence response at acidic pH for recognition of tartaric acids, which is rarely observed for a-PET chemosensors. We propose that the sensing is due to hybrid mechanism of a-PET/d-PET and conformational restriction upon binding. Our results will be useful for design of chiral boronic acid chemosensors with improved fluorescence response at acidic pH, which are rarely reported.     

Green and Practical Synthesis of Carbamates from Ureas and Organic Carbonates

A practical method for the synthesis of carbamates from ureas and organic carbonates was developed with 100% atom economy using La₂O₃/SiO₂ as catalyst without any additional solvent. The scope of the protocol is demonstrated in the synthesis of 14 carbamates with various functional groups in excellent yields (76–95%).

Enantioselective recognition of mandelic acid by a 3,6-dithiophen-2-yl-9H-carbazole-based chiral fluorescent bisboronic acid sensor

We have prepared chiral fluorescent bisboronic acid sensors with 3,6-dithiophen-2-yl-9H-carbazole as the fluorophore. The thiophene moiety was used to extend the π-conjugation framework of the fluorophore in order to red-shift the fluorescence emission and, at the same time, to enhance the novel process where the fluorophore serves as the electron donor of the photoinduced electron transfer process (d-PET) of the boronic acid sensors; i.e., the background fluorescence of the sensor 1 at acidic pH is weaker compared to that at neutral or basic pH, in stark contrast to the typical a-PET boronic acid sensors (where the fluorophore serves as the electron acceptor of the photoinduced electron transfer process). The benefit of the d-PET boronic acid sensors is that the recognition of the hydroxylic acids can be achieved at acidic pH. We found that the thiophene moiety is an efficient π-conjugation linker and electron donor; as a result, the d-PET contrast ratio of the sensors upon variation of the pH is improved 10-fold when compared to the previously reported d-PET sensors without the thiophene moiety. Enantioselective recognition of tartaric acid was achieved at acid pH, and the enantioselectivity (total response K(D)I(F)(D)/K(L)I(F)(L)) is 3.3. The fluorescence enhancement (I(F)(Sample)/I(F)(Blank)) of sensor 1 upon binding with tartaric acid is 3.5-fold at pH 3.0. With the fluorescent bisboronic acid sensor 1, enantioselective recognition of mandelic acid was achieved for the first time. To the best of our knowledge, this is the first time that the mandelic acid has been enantioselectively recognized using a chiral fluorescent boronic acid sensor. Chiral monoboronic acid sensor 2 and bisboronic acid sensor 3 without the thiophene moiety failed to enantioselectively recognize mandelic acid. Our findings with the thiophene-incorporated boronic acid sensors will be important for the design of d-PET fluorescent sensors for the enantioselective recognition of α-hydroxylic acids such as mandelic acid, given that it is currently a challenge to recognize these analytes with boronic acid fluorescent molecular sensors.     

离子碰撞过程中电荷转移的理论研究

用经典轨道蒙托卡罗(CTMC)方法计算离子与氢原子碰撞过程电荷转移截面,并计算俘获电子的n(n为主量子数)壳层分布。对于多电荷离子的碰撞过程,利用约化变量得到了截面的q标度规律。计算结果与实验测量符合得很好。     

ALADDIN原子分子数据库

简介R.Hulse设计的ALADDIN(A Labelled Atomic Data Zaterface)系统的系统软件、数据文件和字典文件等基本特征,并通过一个例子介绍了该系统与用户程序连接的功能。     

Design,Synthesis, and Biological Evaluation of HDAC Degraders with CRBN E3 Ligase Ligands

Histone deacetylases (HDACs) play important roles in cell growth, cell differentiation, cell apoptosis, and many other cellular processes. The inhibition of different classes of HDACs has been shown to be closely related to the therapy of cancers and other diseases. In this study, a series of novel CRBN-recruiting HDAC PROTACs were designed and synthesized by linking hydroxamic acid and benzamide with lenalidomide, pomalidomide, and CC-220 through linkers of different lengths and types. One of these PROTACs, denoted 21a, with a new benzyl alcohol linker, exhibited comparably excellent HDAC inhibition activity on different HDAC classes, acceptable degradative activity, and even better in vitro anti-proliferative activities on the MM.1S cell line compared with SAHA. Moreover, we report for the first time the benzyl alcohol linker, which could also offer the potential to be used to develop more types of potent PROTACs for targeting more proteins of interest (POI).     

Dynamics of a Stochastic SIR Epidemic Model with Logistic Growth

In this paper, a stochastic SIR epidemic model with saturated treatment function, non-monotone incidence rate and logistic growth is studied. First, we prove that the stochastic model has a unique global positive solution. Next, by constructing a suitable Lyapunov function, we can show that there exists an ergodic stationary distribution in the random SIR model. Then, we show that a sufficient condition can make the disease tend to extinction. Finally, some numerical simulations are used to prove our analytical result.     

Rapid identification of chemical constituents in Hugan tablets by ultra-performance liquid chromatography-quadrupole-exactive orbitrap mass spectrometry

Hugan tablet is a Chinese medicine preparation. It is composed of Bupleuri Radix, Artemisiae Scopariae Herba, Isatidis Radix, Schisandrae Chinensis Fructus, Suis Fellis Pulvis, and Vigna radiata L. It has the effects of dispersing stagnated liver qi, strengthening the spleen and eliminating food to be used for the treatment of chronic hepatitis and early cirrhosis. However, the chemical composition of Hugan tablet is complex and not fully understood, which hampers the research in pharmacology. In this study, a reliable method for the rapid analysis and identification of the chemical components in Hugan tablet by their characteristic fragments and neutral losses using ultra-performance liquid chromatography-quadrupole-exactive orbitrap mass spectrometry was developed. A total of 144 chemical components were tentatively identified, including 57 organic acids, 19 flavonoids, 23 alkaloids, 18 lignans, 7 saponins, and 20 others. These components may be the active ingredients of Hugan tablet. The established method can systematically and rapidly analyze the chemical components in Hugan tablet, which provides a basis for the pharmacodynamic substance study and is meaningful for the quality control of Hugan tablet.