Relationship Between Architecture and Adhesion in Polyurethane‐Based Copolymers, 2

Summary: This study describes the chain extension, with polycaprolactone diols, of polyurethane‐graft‐poly(butyl acrylate)s which were first prepared by the step growth polymerization of a mixture of diphenylmethane‐4,4′‐diisocyanate (MDI) and α,α′‐dihydroxyl‐poly(butyl acrylate)s. The success of the chain extension reaction was studied and confirmed by ¹H NMR, SEC and DSC analysis. The incorporation of polycaprolactone sequences in the polyurethane chains modified their specific adhesive properties, bringing cohesion to the material, as demonstrated by tack measurements.

PUR‐graft‐PBA extended with PCL.     

企业员工应激源的因素结构研究

目的 :该研究旨在确立企业员工应激源的因素结构。方法 :经过对 394 6名被试的探索性因素分析 ,提出企业员工应激源的 9因素结构。结果 :因素分别命名为职业发展、住房问题、工作特征、社会环境、人际关系、经济收入、子女问题、组织气氛和夫妻关系。结论 :企业员工应激源的 9因素结构获得了验证性因素分析的支持。     

左心室辅助装置技术现状及未来展望

介绍了临床应用的左心室辅助装置的类型和结构特点,分析了基于生理机制的血泵电机参数的血泵控制策略;提出基于多生理信号约束的控制策略控制血泵输出,易满足受体的需求。结合血泵系统现状,从血泵的结构、穿皮能量传递方式和控制策略等方面探讨今后的研究目标。     

局麻药药代动力学研究进展

药物对映体结构特异性对局麻药药代动力学的各个过程都有着很大影响,包括药物的吸收、蛋白结合率、代谢等。近年研究较多的罗哌卡因和左旋布比卡因作为单一的左旋对映异构体,因其良好的局麻效应和较小的全身毒性正引起广泛的关注。     

The 49 K subunit of NADH: ubiquinone reductase (complex I) from Neurospora crassa mitochondria: primary structure of the gene and the protein

Summary The primary structure of the 49 K subunit of the respiratory chain NADH:ubiquinone reductase (complex I) from Neurospora crassa was determined by sequencing cDNA, genomic DNA and the N-terminus of the mature protein. The sequence lengths correlate to a molecular mass of 54002 daltons for the preprotein and 49239 daltons for the mature protein. The presequence consists of 42 amino acids of typical composition for sequences which target nuclear-encoded proteins into mitochondria. The mature protein consists of 436 amino acids and shows 64% similarity to a 49 K subunit of bovine heart NADH:ubiquinone reductase and 33% to a predicted translation product of an open reading frame in the chloroplast DNAs of Marchantia polymorpha and Nicotiana tabacum. Evidence for an iron-sulfur cluster in the subunit is discussed.     

人偏肺病毒黏附蛋白的二级结构及B细胞表位初步预测

目的预测人偏肺病毒G蛋白的二级结构及B细胞表位。方法分别采用SOPMA方法及HMMTOP程序预测G蛋白的二级结构和跨膜区域；综合分析蛋白的柔性结构、亲水性、表面可及性与抗原性指数，预测G蛋白的抗原表位。结果G蛋白的二级结构主要为柔性区域，占62．1％；廿螺旋占22．37％；β-折叠占15．53％；N端第32～51位氨基酸残基为跨膜区。B细胞表位位于G蛋白N端55—77、80-104、111～126、130～167、178—210区段。结论应用多参数预测G蛋白的二级结构与B细胞表位，为进一步研究蛋白特征、单克隆抗体制备及表位疫苗研制奠定了基础。     

人体熵流的数学模型

伊·普利高津的耗散结构理论中，有一个著名的总熵变公式ｄｓ＝ｄｓｅ＋ｄｓｉ把上述公式用于人体研究，国内外尚未见报导。在前人对人体热力学系统研究的基础上，本文建立了一个人体熵流的数学模型，为进一步展开研究，提供了有力工具并奠定了可靠的理论基础。     

Fine structure and mineral components of fibrous stonelike masses obtained from the human mesenteries

We investigated the fine structure and mineral components of 29 stonelike masses obtained from the mesenteries of four adult cadavers, using optical microscopy, backscattered electron imaging, scanning electron microscopy, energy-dispersive X-ray microanalysis, and X-ray diffraction. Although the overall appearance of the stonelike masses measuring about 5–20mm in diameter and 0.06–3.1g in dry weight was roughly grouped into smooth bulb- and uneven bulk-shaped types, all the calcified masses basically consisted of core and mantle regions. The smooth bulb-shaped masses had a broad mantle with many concentric rings, whereas the uneven bulk-shaped masses contained a large core. In their core regions, spherulitic and short bundle-shaped deposits composed of needle-shaped apatite crystals were mainly found among loose collagen fibers. Their mantle regions, on the other hand, showed the concentric structures of dense collagen fibers in the intra- and/or extrafibrous calcification with fine sandy grain-shaped deposits. The mineral elements were mainly Ca and P, and the major crystals were hydroxyapatite. Hexahedral whitlockite containing Mg was a minor component. The fiber-rich mantle regions showed lower calcification and lesser crystallization than the fiber-poor core region. When necrotic or some tumor adipose tissues and necrotic lymphoid tissues that might have been caused by some digestive diseases are recognized as foreign matter, their tissues occasionally will be calcified and grow into stonelike masses. These stonelike masses tend to occur more often in women than in men.     

Acrylic‐Based Polyurethane/Silica Hybrids Prepared by Acid‐Catalyzed Sol–Gel Process: Structure and Mechanical Properties

Summary: Silica sols were first prepared based on different ratios of tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) by an acid‐catalyzed sol–gel process, and then incorporated into acrylic‐based polyurethanes. The structures and morphologies of silicone‐oxo clusters were studied by ²⁹Si NMR, SAXS, and scanning electron microscopy (SEM), whereas the mechanical properties of polyurethane/silica hybrids were characterized by DMA and tensile tests. The silicone‐oxo clusters in both silica sol and polyurethane hybrids became denser and larger at a higher molar ratio of TEOS/MTES and higher silica content, and the silica‐oxo clusters of polyurethane/silica hybrids even became more compact and larger than those of silica sols, increasing the elastic modulus and tensile strength of polyurethane/silica hybrids.

Typical structure of silica sol prepared from the hydrolysis and condensation of TEOS and MTES with acid as the catalyst.     

In vivo requirements for rDNA chromosome condensation reveal two cell-cycle-regulated pathways for mitotic chromosome folding

Chromosome condensation plays an essential role in the maintenance of genetic integrity. Using genetic, cell biological, and biochemical approaches, we distinguish two cell-cycle-regulated pathways for chromosome condensation in budding yeast. From G(2) to metaphase, we show that the condensation of the approximately 1-Mb rDNA array is a multistep process, and describe condensin-dependent clustering, alignment, and resolution steps in chromosome folding. We functionally define a further postmetaphase chromosome assembly maturation step that is required for the maintenance of chromosome structural integrity during segregation. This late step in condensation requires the conserved mitotic kinase Ipl1/aurora in addition to condensin, but is independent of cohesin. Consistent with this, the late condensation pathway is initiated during the metaphase-to-anaphase transition, supports de novo condensation in cohesin mutants, and correlates with the Ipl1/aurora-dependent phosphorylation of condensin. These data provide insight into the molecular mechanisms of higher-order chromosome folding and suggest that two distinct condensation pathways, one involving cohesins and the other Ipl1/aurora, are required to modulate chromosome structure during mitosis.