Broader pattern of tandem repeats in the mitochondrial control region of Perciformes

Perciformes, the largest order of vertebrates with 20 suborders, is the most diverse fish order that dominates vertebrate ocean life. The complete mitochondrial control region (CR) of Trichiurus japonicus (Trichiuridae, Scombroidei) and Pampus sp. (Stromateidae, Stromateoidei) were amplified and sequenced. Together with data from GenBank, the tandem repeats in the mitochondrial CR from 48 species, which covered nine suborders of Perciformes, are reported in this study. The tandem repeats tend to be long in the suborder Percoidei and Stromateoidei. The identical repeats in 21 species of Cichlidae suggest a common origin and have existed before species divergence. Larimichthys crocea shows tandem repeats instead of the typical structure of the central conserved sequence blocks, which was first reported in Perciformes and vertebrates. This might have resulted from interruption of the polymerase activity during the H-strand synthesis. The four broader patterns presented here for the tandem repeats, including those in both the 5′ and 3′ ends, only in the either 5′ or 3′ end, and in the central conserved domain of the control region, will be useful for understanding the evolution of species.     

Electrochemical corrosion behavior of hot dip coating in artificial seawater

INTR0DUCnONAlloycoatingscandetivelyproteCtsteelagainstcormsioninseri0uscormsionenvir-orunent,suchasthedrinesplashandtidalzones-TwoInainhodiptincaldrinumalloycOaingswidelyusedcommroiallyareGalfancoaing(contalningZn-5wt%kl-us)devel-oPedbytheIntemaionaltalZincReenhheZaionandhocoating(c0n-talningZn-55Wt%Al-1.6Wt%Si)develoPedbytheBethlehemSteelCorpOration-Anewrinc-basedalloycOaingdevel0PedbyNortheaStemUniversityisdiscussedinthesPaperbyelecthehendcalmethod.FromSun(l996),welmOWthecorms…     

淄博市淄川区矿产资源现状及远景规划

淄川区为淄博市辖区之一,位于市境中部,南邻博山区,西接章丘县,北与周村、张店、临淄3区相连,东傍青州市,东南与临朐、沂源2县接壤。东西长49km,南北宽42km,总面积999.07km2。淄川区辖4个街道办事处,14个镇,3个乡,人口为67.29万人。境内自东向西有淄河、孝妇河、范阳河、青杨河4条河流。该区工业较发达,区内的支柱产业为建材、化工、纺织、制药、陶瓷。全区交通以铁路、公路为主,有张博路、胶王路、湖南路等国道和省道,交通非常便利。1矿产资源现状1.1矿产资源的基本特点淄川区在地层区划上属于华北地层区、鲁西地层分区、泰安地层小区。在…     

Effects of varying densities on serum reproductive parameters in pen-reared juvenile female rainbow trout <Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis> farms

The primary goal of this study was to assess the effect of varying densities on serum reproductive parameters of immature rainbow trout Oncorhynchus mykiss. Experimental trout were maintained in intensive, pen-reared farms for 300 days in fresh water reservoirs. Initial densities were 4.6, 6.6, and 8.6 kg/m³ (40, 60, 80 ind./m³), indicated as SD1, SD2, SD3, and final densities were 31.1, 40.6, 49.3 kg/m³, respectively. A summary of the ovarian stages were observed by histological examination. Serum E₂ (estradiol), T (testosterone) were evaluated by radioimmunoassay and FSH (follicle-stimulating-hormone), LH (luteinizing-hormone), vitellogenin, 17α,20β-P (17α,20βdihydroxy4-pregnen-3-one) were measured by enzyme-linked immunosorbent assay. Our findings demonstrated that ovarian development were retarded (from stage III to stage IV) at highest rearing density (SD3) after 180 days of intensive culture (over 40.6 kg/m³). In addition, we observed an inverse relationship between serum reproductive parameters and rearing density. Furthermore, compared to serum reproductive parameters of SD1, E₂, T, FSH, vitellogenin, 17α,20β-P, GSI and LH of two higher density groups decreased firstly and significantly at 60 (over 15.9 kg/m 3 ), 180 (over 31.7 kg/m 3 ), 180 (over 40.6 kg/m³), 240 (over 36 kg/m³), 240 (over 36 kg/m³), 240 (over 45 kg/m³) and 300 (over 49.3 kg/m³) days, respectively. Comparing serum reproductive parameters within the same ovarian development stage of rainbow trout from varying densities revealed that higher population density also led to significantly lower overall serum reproductive parameters. Overall, this study presents the reproductive, endocrinological parameters of juvenile female rainbow trout at high rearing densities and indicates the need for rainbow trout (114.44±5.21 g, 19.69±0.31 cm) that are initially stocked at 6.6 or 8.6 kg/m³ should be classified and subdivided into lower density after 180 days of farming (not over 31.7 kg/m³).     

Effect of Ca(OH)2, NaCl,and Na2SO4 on the corrosion and electrochemical behavior of rebar

The corrosion of rebar in reinforced concrete in marine environments causes significant damage to structures built in ocean environments. Studies on the process and mechanism of corrosion of rebar in the presence of multiple ions may help to control damage and predict the service life of reinforced concrete structures in such environments. The effect of interactions between sulfate and chloride ions and calcium hydroxide on the electrochemical behavior of rebar are also important for evaluation of structure durability. In this work, electrochemical impedance spectroscopy(EIS) plots of rebar in Ca(OH)_2 solution and cement grout, including NaCl and Na_2SO_4 as aggressive salts, were measured for different immersion times. The results show that corrosion of rebar was controlled by the rate of charge transfer as the rebar was exposed to chloride solution. In the presence of high concentrations of sulfate ions in the electrolyte, generation and dissolution of the passive film proceeded simultaneously and corrosion was mainly controlled by the diffusion rate. When Na_2SO_4 and NaCl were added to Ca(OH)_2 solution, the instantaneous corrosion rate decreased by a factor of 10 to 20 as a result of the higher p H of the corroding solution.     

地面重力时空变化向卫星高度的解析延拓

为研究卫星在不同高度对地面重力变化的检测能力,利用地面获得的重力场时间和空间变化,采用空间域向上解析延拓原理,将地面数据向上解析延拓到数百千米的不同高度。计算分析表明,如果地表存在93×10-8ms-2的重力变化量,在450km高度可观测到20×10-8ms-2的重力变化。所以利用卫星重力观测技术进行地震监测,其观测精度应优于20×10-8ms-2。     

Screening and molecular classification of low-temperature protease from Antarctic microorganism and its characterization

107 strains producing protease were screened from 260 strains of Antarctic psychrophilic bacteria, among which proteolytic activity of five strains was more than 45 U ml^-1. The 16S rRNA gcne sequences homology and phylogcnetic analysis of five Antarctic psychrophillc bacteria showed that NJ276, NJS-9, NJ16-70,NJ345 belonged tO the described genus Pseudoalteromonas and NJ341 belonged to the genus Colwellia. The growth and the protease characteristic of four Antarctic psychrophilic bacteria had been studied, and the result showed that the 6ptimal temperature for growth and protease-produeing of four strains was about 10℃. Their growth and protease-produeing were still high during incubatlng 2-5 days. The maximum proteolytic activity occurred at pH 9 for four Antarctic psychrophilic bacteria. The optimal temperature of protease action of both strains NJ276 and NJ5-9 was about 50℃, however, the optimal temperature of protease aetlon of both strains NJ341 and NJ345 was about 40 ℃, and their proteolytic activity under 0℃ exhibited nearly 30% of the maximum activity, but their thermal stabilities were weaker. These results indicated that proteases from NJ341 and NJ345 were low-temperature proteases.     

Integration of the full two-body problem by using generalized inertia integrals

A new algorithm to integrate the full two-body problem based on generalized inertia integrals is given. The computation speed is comparable to the fastest algorithm available till now which is based on spherical harmonics.     

The Key Techniques and Design Features of YH-1 Mars Probe

In this paper, the function and composition as well as the key techniques (ultra-long distance communication, attitude determination and control, thermal control, ultra-low temperature acclimatization, etc.) of China's first Mars probe are analyzed. In combination with practical engineering conditions, the solutions of these key techniques are given. The design features of the probe are summarized, as a reference for developing the probes of the subsequent related missions in China.