关于可列非齐次马氏链状态三元序组出现频率的一类强大数定律

本文通过可列非齐次马氏链在 Wiener 概率空间中的一种实现,给出了关于状态三元序组出现频率的一类强大数定律.     

Subunit‐Specific Labeling of Ubiquitin Chains by Using Sortase: Insights into the Selectivity of Deubiquitinases

Information embedded in different ubiquitin chains is transduced by proteins with ubiquitin‐binding domains (UBDs) and erased by a set of hydrolytic enzymes referred to as deubiquitinases (DUBs). Understanding the selectivity of UBDs and DUBs is necessary for decoding the functions of different ubiquitin chains. Critical to these efforts is the access to chemically defined ubiquitin chains bearing site‐specific fluorescent labels. One approach toward constructing such molecules involves peptide ligation by sortase (SrtA), a bacterial transpeptidase responsible for covalently attaching cell surface proteins to the cell wall. Here, we demonstrate the utility of SrtA in modifying individual subunits of ubiquitin chains. Using ubiquitin derivatives in which an N‐terminal glycine is unveiled after protease‐mediated digestion, we synthesized ubiquitin dimers, trimers, and tetramers with different isopeptide linkages. SrtA was then used in combination with fluorescent depsipeptide substrates to effect the modification of each subunit in a chain. By constructing branched ubiquitin chains with individual subunits tagged with a fluorophore, we provide evidence that the ubiquitin‐specific protease USP15 prefers ubiquitin trimers but has little preference for a particular isopeptide linkage. Our results emphasize the importance of subunit‐specific labeling of ubiquitin chains when studying how DUBs process these chains.     

山东是战国秦汉时期丝绸之路的主要供货地

从大量资料分析,战国秦汉时期丝绸之路的主要供货地是山东。一是山东在丝路最繁忙的时期是全国丝绸业最发达的地方;二是汉代丝绸之路上输出的丝绸主要是平素类织物,与齐鲁地方产品相一致;三是丝绸之路上已出土的丝绸中,确有明确标为山东所产的。     

CC12型汽轮机低真空供热的安全经济性分析

通过汽轮机变工况计算及凝汽器的热力计算 ,分析了营口化纤厂自备电厂CC1 2型汽轮机低真空供热对汽轮机电功率、轴向推力、汽缸膨胀、凝汽器冷却管膨胀的影响 ,进而分析了CC1 2型汽轮机低真空供热的安全性和经济性 ,并对该汽轮机低真空供热的效益进行了计算及分析。该汽轮机经过 4个月的低真空供热运行 ,证明计算分析结果是正确的     

氯碱工业在柴达木国家循环经济示范区的作用

介绍了青海盐湖工业集团股份有限公司在柴达木国家循环经济示范区,以氯碱化工为基础,科学合理地构建循环经济模式的主要内容。     

销售努力成本分担情况下供应链回购契约研究

考虑由一个供应商和一个零售商构成的二级供应链,需求是随机的且受销售努力水平的影响。本文首先分析了回购契约无法协调的原因;然后在销售努力成本分担的情况下,提出了分别通过限定回购系数和分担努力成本系数使供应链得以协调。     

蓄热式电热蒸汽锅炉

介绍了蓄热式电热蒸汽锅炉供热系统的供热原理、装置配置和设计要点 ,该供热系统具有广阔的应用前景。     

A Dye-Sensitized Nanoporous TiO2 Photoelectrochemical Cell with Novel Gel Network Polymer Electrolyte

A novel gel network polymer electrolyte based on polysiloxane with internal plasticizing PEO chains was applied in fabricating solid-state dye-sensitized TiO₂ photoelectrochemical cells. Ethylene carbonate (EC)/propylene carbonate (PC) and LiI/I₂ were added as liquid plasticizer to improve the performance. The cells showed open circuit voltage of 0.69 V and short circuit current density of 1.7 mA cm^–2 under 28 mW cm^–2 white light illumination. The energy conversion efficiencies and fill factors of the cells were 2.9% and 0.72.     

Effect of molecular weight on crystallization of semirigid poly(phenylene sulfide) under shear flow

Isothermal crystallization of poly(phenylene sulfide) with three molecular weights (M_w = 22k, 48k, and 52k, respectively) under shear condition has been investigated. It appears that shear can induce all these three PPS samples to form a thread‐like crystal structure which consists of the numerous stable nuclei that align tightly in the direction of shear. Crystallization kinetics of PPS has been greatly influenced by shear flow. Higher shear rate and long shear time can lead to decrease of spherulite growth rate of PPS. Also, the spherulite growth rate of PPS is affected by supercoolings and molecular weight. For the lower molecular weight (M_w = 22k), the spherulite growth rate is independent on the shear rate and shear time; while for the higher ones (M_w = 48k and 52k), with the increasing of shear rate, the spherulite growth rate of PPS increases to reach maximum at first, and then decreases. The lower the crystallization temperature is, the more the spherulite growth rate changes, showing that higher orientation of molecular chains can be obtained more easily with increased supercooling. A model has been proposed to explain the mechanism of thread‐like crystal formation under shear flow. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Theoretical framework for formulating MIP scheduling models with multiple and non-uniform discrete-time grids

We present a framework for the formulation of MIP scheduling models based on multiple and nonuniform discrete time grids. In a previous work we showed that it is possible to use different (possibly non-uniform) time grids for each task, unit, and material. Here, we generalize these ideas to account for general resources, and a range of processing characteristics such as limited intermediate storage and changeovers. Each resource has its own grid based on resource consumption and availability allowing resource constraints to be modeled more accurately without increasing the number of binary variables. We develop algorithms to define the unit-, task-, material-, and resource-specific grids directly from problem data. Importantly, we prove that the multi-grid formulation is able to find a schedule with the same optimal objective as the discrete-time single-grid model with an arbitrarily fine grid. The proposed framework leads to the formulation of models with reduced number of binary variables and constraints, which are able to find good solutions faster than existing models.