Interval design point method for calculating the reliability of structural systems

The evaluation of reliability for structural system is important in engineering practices.In this paper,by combining the design point method,JC method,interval analysis theory,and increment load method,we propose a new interval design point method for the reliability of structural systems in which the distribution parameters of random variables are described as interval variables.The proposed method may provide exact probabilistic interval reliability of structures whose random variables can have either a normal or abnormal distribution form.At last,we show the feasibility of the proposed approach through a typical example.     

Enzyme-catalyzed synthesis of a novel thermosensitive polyester with pendant ketoprofen

A novel thermosensitive polyester with pendant ketoprofen was synthesized by copolymerization of PEG 800 with 2‐ketoprofendimethylmalate using CAL‐B at 70 °C. The products were characterized by NMR spectra and GPC. The in vitro study demonstrated that the polyester could release ketoprofen in physiological conditions, which indicates that the polyester could be a promising prodrug.

     

Dynamic interaction between the growing Ca–P minerals and bacterial cellulose nanofibers during early biomineralization process

Bone is a composite of organic phase (collagen nanofibers) and Ca–P minerals (hydroxylapatite) and an important biological structure in the field of biomineralization, but the interaction between organic matrixes and inorganic minerals is still too ambiguous. In order to investigate the interaction between the growing Ca–P minerals and organic nanofibers during early biomineralization process, bacterial cellulose (BC) nanofibers were used as templates to mimic collagen nanofibers for Ca–P minerals deposition via biomineralization for periods from as short as 4–72 h. Our findings pointed out that the resultant Ca–P minerals formed on BC nanofibers were platelet-like calcium-deficient HAp which was analogous to those in natural bone tissue. Strikingly, we found that the growth of Ca–P minerals had influence on the structure and properties of BC nano-templates during biomineralization process.     

部分线性模型中估计的渐近正态性

考虑回归模型其中是未知函数，（ｘ＿ｉ，ｔ＿ｉ，ｕ＿ｉ）是固定非随机设计点列，β是待估参数，ｅ＿ｉ是随机误差。基于ｇ（·）及ｆ（·）的一类非参数估计（包括常见的核估计和近邻估计），我们构造了β的加权最小二乘估计，并证得了最小二乘估计和加权最小二乘估计的渐近正态性。     

Synthesis and Antibacterial Activities of Novel Biphenyltetrazole Derivatives Bearing 1,3,4‐Oxadiazole

Several new 5‐[4′‐(5‐phenyl‐1,3,4‐oxadiazol‐2‐ylsulfanylmethyl)‐biphenyl‐2‐yl]‐tetrazoles derivatives have been synthesized. The structures of these new compounds were confirmed by elementary analyses and spectral data. The antibacterial activities of the compounds were also evaluated.     

The Application of CdSe Quantum Dots with Multicolor Emission as Fluorescent Probes for Cell Labeling

Herein, highly luminescent CdSe quantum dots (QDs) with emissions from the blue to the red region of visible light were synthesized by using a simple method. The emission range of the CdSe QDs could be tuned from λ=503 to 606 nm by controlling the size of the CdSe QDs. Two amino acids, L ‐tryptophan (L ‐Trp) and L ‐arginine (L ‐Arg), were used as coating agents. The quantum yield (QY) of CdSe QDs (green color) with an optimized thickness could reach up to 52 %. The structures and compositions of QDs were examined by using X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Optical properties were studied by using UV/Vis and photoluminescence (PL) spectroscopy and a comparison was made between uncoated and coated CdSe QDs. The amino acid‐modified β‐cyclodextrin (CD)‐coated CdSe QDs presented lower cytotoxicity to cells for 48 h. Furthermore, amino acid‐modified β‐CD‐coated green CdSe QDs in HepG2 cells were assessed by using confocal laser scanning fluorescence microscopy. The results showed that amino acid‐modified β‐CD‐coated green CdSe QDs could enter tumor cells efficiently and indicated that biomolecule‐coated QDs could be used as a potential fluorescent probe.     

大孔载体固定化微生物处理污水研究

通过载体结合法将高效微生物菌群B500或活性污泥固定于不同材质的大孔载体之上,得到固定化微生物.所得固定化微生物置于曝气水槽中,依所用载体密度的不同而形成流化床及固定床型固定化微生物污水处理技术.用所得工艺进行了生活及化工污水的生物处理研究,探讨了不同载体、床型的污水处理能力及其影响因素,考察了相应的CODCr、NH4 -N去除动力学特征.应用克氏定氮法考察了所得大孔载体的微生物负载量,并借助SEM观察了固定化微生物前后载体的表面形态.结果表明,固定化微生物流化床适合于高浓度污水的处理,固定化微生物固定床则在高效去除污水中污染物的同时亦有利于悬浮物的去除,且两种固定化微生物床型处理实际污水时的耐冲击性能良好,出水CODCr、NH4 -N均达到国家污水综合排放一级标准,具有一定的应用前景.     

Recursive least squares parameter estimation algorithm for dual-rate sampled-data nonlinear systems

This paper focuses on the identification problem of Hammerstein systems with dual-rate sampling. Using the key-term separation principle, we derive a regression identification model with different input updating and output sampling rates. To solve the identification problem of the dual-rate Hammerstein systems with the unmeasurable variables in the information vector, an auxiliary model-based recursive least squares algorithm is presented by replacing the unmeasurable variables with their corresponding recursive estimates. Convergence properties of the algorithm are analyzed. Simulation results show that the proposed algorithm can estimate the parameters of a class of nonlinear systems.     

Multi-frequency switch and excellent slow light based on tunable triple plasmon-induced transparency in bilayer graphene metamaterial∗

We propose a novel bilayer graphene terahertz metamaterial composed of double graphene ribbons and double graphene rings to excite a dynamically adjustable triple plasma-induced transparency (PIT) effect. The coupled mode theory (CMT) is used to explain the PIT phenomenon, and the results of the CMT and the finite-difference time-domain simulation show high matching degree. By adjusting the Fermi levels of graphene, we have realized a penta-frequency asynchronous optical switch. The performance of this switch, which is mainly manifested in the maximum modulation depth (MD = 99.97%) and the minimum insertion loss (IL = 0.33 dB), is excellent. In addition, we have studied the slow-light effect of this triple-PIT and found that when the Fermi level of graphene reaches 1.2 eV, the time delay can reach 0.848 ps. Therefore, this metamaterial provides a foundation for the research of multi-frequency optical switches and excellent slow-light devices in the terahertz band.     

梁宗岱与象征主义诗学

梁宗岱对深化中国诗人关于象征主义的理解所做出的杰出贡献尚未得到学界充分认可。作为诗人、文学批评家和翻译家,梁展示了他极高的外语语言才能;当论及他对艺术与美、理想与“纯诗”的至高无上的信仰,并阐发他所理解的思想与感觉、个性与共性、小我与宇宙、传统与现代的关系时,确是深得象征派大师瓦雷里的精髓。他捍卫诗的形式、结构,诗意背后有意的探寻、思想的揉折,以及反复推敲、精打细磨的艰苦的劳作,这与浪漫主义的灵光一现、一气呵成形成了鲜明的对照。梁宗岱的主要理论著述曾激励“新月派”诗人倡导新诗的形式革命,并对三十年代最有才华的诗人之一卞之琳产生了重大的影响,又在四十多年以后令“后朦胧诗派”的“四川五君子”深深地为之折服,激励他们在尊重传统的同时开创自己的新诗之路。