具有两次透射的无光焦度校正透镜组的准施密特系统

介绍了一种具有两次透射的无光焦度校正透镜组的准施密特系统及其设计思想和方法，并给出了一个设计结果。焦距２．７ｍ，相对孔径Ｆ／５．５，视场角３．４２°。在全视场范围内成像质量达到了衍射极限。     

Self‐Assembly through Coordination and π‐Stacking: Controlled Switching of Circularly Polarized Luminescence

Multiple noncovalent interactions can drive self‐assembly through different pathways. Here, by coordination‐assisted changes in π‐stacking modes between chromophores in pyrene‐conjugated histidine (PyHis), a self‐assembly system with reversible and inversed switching of supramolecular chirality, as well as circularly polarized luminescence (CPL) is described. It was found that l ‐PyHis self‐assembled into nanofibers showing P‐chirality and right‐handed CPL. Upon Zn^II coordination, the nanofibers changed into nanospheres with M‐chirality, as well as left‐handed CPL. The process is reversible and the M‐chirality can change to P‐chirality by removing the Zn^II ions. Experimental and theoretical models unequivocally revealed that the cooperation of metal coordination and π‐stacking modes are responsible the reversible switching of supramolecular chirality. This work not only provides insight into how multiple noncovalent interactions regulate self‐assembly pathways.     

Encapsulation of a Phase‐Change Material in Nanocapsules with a Well‐Defined Hole in the Wall for the Controlled Release of Drugs

As a class of biocompatible and biodegradable phase‐change materials, natural fatty acids have received considerable interest in recent years for temperature‐controlled release of drugs. However, the poor dispersibility and colloidal stability of their nanoparticles under physiological conditions place a major limitation on their applications in biomedicine. Herein, we report a facile method for encapsulating a mixture of two natural fatty acids (with a eutectic melting point at 39 °C) in a biocompatible, silica‐based nanocapsule to achieve both stable dispersion and controllable release of drugs. The nanocapsules have a well‐defined hole in the wall to ensure easy loading of fatty acids, together with multiple types of functional components such as therapeutics and near‐infrared dyes. The payloads can be released through the hole when the fatty acids are melted upon photothermal heating. The release profile can be controlled by varying the size of the hole and/or the duration of laser irradiation.     

空调冷凝热热回收技术研究现状及发展趋势

界定了空调冷凝热热回收系统的分类,总结了国内外空调冷凝热热回收技术的研究现状,提出了空调冷凝热热回收技术的发展趋势。     

热泵中定容水箱保温率的研究

提出定容水箱保温率的概念及其方程。为此,本实验对定容水箱自然冷却过程中各热力参数进行了测量。根据实验所测数据及相关公式推导,得到保温率方程的经验函数关系式。同时,通过对测量曲线和经验函数曲线的拟合,验证了定容水箱保温率方程。     

Graphs are (1,Δ+1)-choosable

A graph $G$ is $(k,k^{\prime })$-choosable if the following holds: For any list assignment $L$ which assigns to each vertex $v$ a set $L\left(v\right)$ of $k$ real numbers, and assigns to each edge $e$ a set $L\left(e\right)$ of $k^{\prime }$ real numbers, there is a total weighting $?:V\left(G\right)\cup E\left(G\right)\to R$ such that $?\left(z\right)\in L\left(z\right)$ for $z\in V\cup E$, and ${\sum }_{e\in E\left(u\right)}?\left(e\right)+?\left(u\right)\ne {\sum }_{e\in E\left(v\right)}?\left(e\right)+?\left(v\right)$ for every edge $uv$. This paper proves that if $G$ is a connected graph of maximum degree $\Delta \ge 2$, then $G$ is $(1,\Delta +1)$-choosable.     

Hybrids of MnO<Subscript>2</Subscript> nanoparticles anchored on graphene sheets as efficient sulfur hosts for high-performance lithium sulfur batteries

Lithium–sulfur (Li–S) battery is considered as a promising option for electrochemical energy storage applications because of its low-cost and high theoretical capacity. However, the practical application of Li–S battery is still hindered due to the poor electrical conductivity of S cathode and the high dissolution/shuttling of polysulfides in electrolyte. Herein, we report a novel physical and chemical entrapment strategy to address these two problems by designing a sulfur–MnO₂@graphene (S–MnO₂@GN) ternary hybrid material structure. The MnO₂ particles with size of ~ 10 nm are anchored tightly on the wrinkled and twisted GN sheets to form a highly efficient sulfur host. Benefiting from the synergistic effects of GN and MnO₂ in both improving the electronic conductivity and hindering polysulfides by physical and chemical adsorptions, this unique S–MnO₂@GN composite exhibits excellent electrochemical performances. Reversible specific capacities of 1416, 1114, and 421 mA h g^?1 are achieved at rates of 0.1, 0.2, and 3.2 C, respectively. After a 100 cycle stability test, S–MnO₂@GN composite cathode could still maintain a reversible capacity of 825 mA h g^?1.     

Improvement of performance in label-free quantitative proteome analysis with monolithic electrospray ionization emitter

The postcolumn void volume, which is introduced by the connecting tubing and void ESI emitter in the nanoflow LC coupled with MS/MS system (microLC-MS/MS), is harmful for the analysis of peptides in shotgun proteome analysis. A new type of porous C12 monolithic ESI emitter was prepared to eliminate the disruption and mixing effects occurring in the connecting tubing and void emitter. It was demonstrated that the porous hydrophobic monolith inside the emitter played a key role in retaining the good peak profile, and the average peak capacity of the whole separation system increased 12.8% in contrast to commercially available void emitter. Then, the porous C12 monolithic emitter was applied in label-free quantitative proteome analysis of two standard protein mixtures that were spiked into the tryptic digest of mouse livers extract. Compared to commercially available void ESI emitter, the number of proteins with reliable results in quantification increased greatly. And the relative quantities of the four standard proteins were all determined with the relative error < or = 6.8%. However, quantitative information of only three standard proteins could be obtained when void emitter was used.     

Synthesis of (S)-, (R)-, and (rac)-2-amino-3,3-bis(4-fluorophenyl)propanoic acids and an evaluation of the DPP IV inhibitory activity of Denagliptin diastereomers

The non-proteinogenic amino acid (2S)-2-amino-3,3-bis(4-fluorophenyl)propanoic acid [(S)-1] is a key intermediate required for the synthesis of Denagliptin (2a). Denagliptin is a dipeptidyl peptidase IV (DPP IV) inhibitor that is being developed for the treatment of type-2 diabetes mellitus. A diastereoselective, cost-efficient synthetic procedure for (S)-1 was developed by alkylating a Ni(II) glycine equivalent derived from (S)-2-[(N-benzylprolyl) amino] benzophenone [(S)-BPB]. The alkylated product was then decomposed to isolate the target amino acid (S)-1 (ee >99%) and ligand (S)-BPB, which can be reused in subsequent reactions. The enantiomer (R)-1 and racemate (rac)-1 were synthesized from their corresponding Ni(II) glycine equivalents. Denagliptin diastereomers (2), derived from the key intermediates (S)-1, (R)-1, and (rac)-1 were synthesized, and their dipeptidyl peptidase IV inhibitory activities were investigated. These findings are important in the design and synthesis of DPP IV inhibitors.