Structure of the dimerized hormone-binding domain of a guanylyl-cyclase-coupled receptor

The atrial natriuretic peptide (ANP) hormone is secreted by the heart in response to an increase in blood pressure. ANP exhibits several potent anti-hypertensive actions in the kidney, adrenal gland and vascular system. These actions are induced by hormone binding extracellularly to the ANP receptor, thereby activating its intracellular guanylyl cyclase domain for the production of cyclic GMP. Here we present the crystal structure of the glycosylated dimerized hormone-binding domain of the ANP receptor at 2.0-A resolution. The monomer comprises two interconnected subdomains, each encompassing a central beta-sheet flanked by alpha-helices, and exhibits the type I periplasmic binding protein fold. Dimerization is mediated by the juxtaposition of four parallel helices, arranged two by two, which brings the two protruding carboxy termini into close relative proximity. From affinity labelling and mutagenesis studies, the ANP-binding site maps to the side of the dimer crevice and extends to near the dimer interface. A conserved chloride-binding site is located in the membrane distal domain, and we found that hormone binding is chloride dependent. These studies suggest mechanisms for hormone activation and the allostery of the ANP receptor.     

浅谈高职院校思想政治教育的创新

高校思想政治教育要克服在落实教育目标过程中的不足,要拓宽教育途径,为了做好高校思想政治教育工作,作者提出了进行观念上的创新、内容上的创新、教育方法上的创新的方法.     

Determination of the optical thickness and effective particle radius of clouds from transmitted solar radiation measurements

A method is presented for determining the optical thickness (τc) and effective particle radius (re) of stratiform cloud layers from transmitted solar radiation measurements. A detailed study shows that the cloud optical thickness and effective particle radius of water clouds can be determined from transmission function measurements at 0.75 and 2.13 μm, provided that the scaled optical thickness τ′0.75>1 and re>5 μm. The wavelengths adopted by our study are similar to the channels of the moderate resolution imaging spectrometer (MODIS). The proposed method is invalid for optically thin clouds since transmission at 2.13 μm is less sensitive to re. The retrieval errors of τ′0.75 and re monotonically decrease with increasing τc. For clouds having τ′0.75≥2, the retrieval errors of τ′0.75 and re are below 10% and 20%, respectively. Transmissions at 0.75 and 1.65 μm can also be used to retrieve τc and re.     

复变函数在换元积分法中的应用

讨论了复变函数方法在换元积分法中的应用．     

复合工业助磨剂助磨性能研究

本文对复合工业助磨剂的助磨性能进行了研究 ,研究表明在粉磨过程中添加少量助磨剂到欲粉磨物料中 ,即能吸附在物料颗粒的表面上 ,通过物理化学或化学作用产生力学效能 ,从而加速粉磨过程的进行。本文还对应用工业废料开发助磨剂新品种的可行性进行了研究     

A 65-nm 1-Gb NOR floating-gate flash memory with less than 50-ns access time

This paper presents a 65-nm 1-Gb NOR-type floating-gate flash memory, in which the cell device and chip circuit are developed and optimized. In order to solve the speed problem of giga-level NOR flash in the deep submicron process, the models of long bit-line and word-line are first given, by which the capacitive and resistive loads could be estimated. Based on that, the read path and key modules are optimized to enhance the chip access property and reliability. With the measurement results, the flash memory cell presents good endurance and retention properties, and the macro is operated with 1-las/byte program speed and less than 50-ns read time under 3.3 V supply.     

摩擦焊接头组织与力学性能

研究了变形速率对低合金结构钢摩擦焊接头组织与力学性能的影响，结果表明，增大变形速率和延长减速改善了接头区域的硬度分布，焊缝区宽度变窄，热影响软化区不明显，焊缝晶粒细化，使焊缝的韧性得到一定程度的改善，本文对接头各个区域的显微组织进行了分析。     

循环流化床燃烧技术的发展及其应用前景展望

本文针对我国能源领域如何贯彻“开发与节约并重”的方针，实现高效洁净利用煤炭资源，有效地保护自然环境的课题，讨论了目前在国际燃烧技术领域具有领先水平的循环流化床技术的应用与发展，展望了该技术在山西省的应用前景     

托品酰胺合成中缩合反应研究

在制备托品酰胺的工艺中，如何选用托品酸和Ｎ－乙基－Ｎ－胺的缩合酰化的碱性溶媒，以便于后处理是实现工业化生产很重要的课题。常用的碱性溶媒有ＮａＯＨ、ＮａＯＡｃ、Ｎａ２Ｃｏ３和吡啶等，吡啶既可做溶剂又可和氯化氢，还可与酰氯形成络和物而增强酰化能力，理论产率很高，但后处理困难，实际产率反而很低。用Ｋ２ＣＯ３不仅实际产率提高而且减少了劳动强度和污染，适应了工业化大生产。     

HT30-54灰铸铁激光表面淬火研究

本文研究了不同涂层条件下,对HT30-54灰铸铁进行激光处理的工艺参数与硬化层深度的关系,以及工艺参数与显微组织和硬度的关系。结果表明,选用扫描速度7～28mm/s,输出功率450～840W时,硬化层的显微组织是针状马氏体加片状石墨,表面硬度值是HV_(0.05)800。