35MnBM钢350 mm×470 mm连铸坯的试制

通过控制 (P +S)≤ 0 .0 40 %及Al 0 .0 2 0 %～ 0 .0 40 %和连铸生产工艺可以成功生产 3 5MnBM钢3 5 0mm× 470mm连铸坯。用该工艺生产的Φ65～ 85mm规格的 3 5MnBM成品材的质量水平与模铸相当     

宝钢集团五钢公司生产优质连铸轴承钢材

宝钢集团五钢公司在 1997年建成了具有国际一流水平的大电炉—炉外精炼—连铸生产线 ,并在该生产线上开发了小方坯连铸轴承钢技术。生产的连铸材的氧化物总量比模铸材减少 2 0 % ,Al2 O3和 Mg O减少 46 %及 36 % ,氧化夹杂物平均直径比模铸少 8%。此外 ,连铸工艺生产的 35 mm轴承钢材的接触疲劳寿命 L1 0 是模铸材的 1.3倍以上 ,5 0m m轴承钢材的疲劳寿命 L5 0 是模铸材的 1.87倍以上 ,且连铸材的弥散性及均匀性均优于模铸材宝钢集团五钢公司生产优质连铸轴承钢材@尚恬…     

60Si2CrVAT弹簧钢EAF-LF(VD)-CC工艺实践

用 10 0tUHPEAF +LF(VD) + 30 0mm方CC工艺生产提速铁路车辆用弹簧钢 6 0Si2CrVAT的工艺实践表明 ,钢的清洁度为 [O]10× 10 - 6 ,S 0 .0 0 5 % ,P 0 .0 12 % ,连铸时用结晶器 +凝固末端电磁搅拌 ,使连铸坯中心碳偏析指数达 1.0 8。     

新日铁公司八幡厂一号连铸机设备改造

为调整八幡厂的连铸生产 ,在其一号连铸机上生产不锈钢、高碳钢及 3% Cr- SML 钢等特殊钢 ,将其中的一流改为板坯 /方坯连铸共用机构。该连铸机为弧型连铸机 ,六点矫直 ,弧型半径为 10 .5m。连铸板坯尺寸为 2 5 0 mm× 6 5 0～ 16 5 0 m m、2 90× 190 0mm,最大连铸速度为 1.4m/ m in;连铸方坯尺寸为 2 2 0 mm× 2 2 0 mm、 2 90 m m× 2 90 m m,最大连铸速度为1.9m/ m in。中间包容量为 30 t。(1)钢包回转台具有可适用 35 0 t钢包和 16 0 t钢包的特点。(2 )为适应板坯一流连铸或方坯三流连铸 ,有上插入引锭杆装置和下插入引锭杆装置。(3)…     

中碳钢连铸小方坯表面缺陷与保护渣性能选择

首钢第二炼钢厂160mm×160mm小方坯连铸使用高碳钢用FRK-45型保护渣生产碳含量为0．35％-0．50％的中碳钢时,大量连铸坯表面出现纵裂和横向凹坑。通过降低连铸机拉速、提高保护渣碱度及延缓保护渣熔速,改善了连铸坯坯壳与结晶器壁间的渣膜传热,使连铸坯的表面缺陷得到了有效控制。     

锻轧钢棒用连铸圆坯品种开发

主要研究100 t电炉→LF炉精炼+VD真空脱气处理→连铸→入坑缓冷→精整工艺流程生产锻轧钢棒用连铸圆坯的各项工艺控制点。通过工艺优化,开发生产的S355NL/S355J2G3低合金钢、CrMo钢、C45R/S45CrS优碳钢系列锻轧钢棒用连铸圆坯,圆坯内外部质量优良,锻轧而成的钢棒洁净度高、热处理性能稳定,探伤合格率达到99.6%以上,产品质量满足国际市场要求。     

短流程生产20CrMnTi齿轮钢

随着我国汽车工业的稳步发展 ,对齿轮钢的需求量越来越大 ,据权威部门预测 ,2 0 0 0年将达到 36～ 38万ｔ,其中 2 0ＣｒＭｎＴｉ占据 85%以上。五钢公司新建的 1 0 0ｔ电炉及ＬＦ ＶＤ二次精炼装置和连铸、连轧三位一体的短流程生产线 ,为生产高质量的齿轮钢提供了保证。 1 998年 3月份至今 ,短流程生产线生产的 2 0ＣｒＭｎＴｉ连铸坯已累计 55炉 ,铸坯量 540 0ｔ,成材 4 50 0ｔ,产品合格率 1 0 0 % ,本文仅就 1 40方连铸坯成材的生产情况进行分析。1　 2 0ＣｒＭｎＴｉ钢主要技术指标( 1 )化学成份 ( % ) :Ｃ 0 .1 8～ 0 .2 3,Ｓｉ 0 .1 7…     

包钢薄板坯连铸连轧工程进展顺利

包头钢铁公司薄板坯连铸连轧工程进展顺利 ,预计2 0 0 1年下半年试车 ,现正进行设备安装 ,有关配套工程正抓紧进行。该工程设计年产 2 0 0万 t,配备有 2 10 t转炉 ,二机二流薄板坯连铸机及连轧生产线 ,可生产薄板坯 10 0万 t,热轧板卷 99万 t,能生产厚度 1.2～ 2 0 m m、宽 980～ 15 0 0 mm的热轧板包钢薄板坯连铸连轧工程进展顺利@包新     

NKK京滨厂开发φ330mm圆坯连铸技术

日本 NKK公司京滨厂过去采用铸锭—开坯工艺生产无缝钢管及条钢用的3 30 mm大断面圆坯。最近 ,为了降低坯料成本 ,提高产品成材率 ,对该厂的 5号连铸机 (圆坯连铸机 )进行了改造 ,开发了 33 0 mm圆坯连铸技术。该 5号连铸机是 6流弧型连铸设备 ,考虑到 3 3 0 m m的需要量 ,只改造其中的 1流改造 ,铸造的钢种为 0 .18%～0 .4 8% C钢 (包括一部分高强度钢 )及 2 .2 5% Cr钢。经改造后 ,通过实际操作 ,得到了良好的结果。连铸出的33 0 mm大断面圆坯 ,其表面和内部均无裂纹等缺陷 ,中心疏松也很小 ,振痕部的凹度与同时铸造的33 0 mm…     

提高连铸机用辊子使用寿命的技术

1　前言为提高连铸机的生产效率和实现节能、节省资源的目的 ,以前用的喷镀连铸机辊 (以下称连铸辊 ) W2 4 0 ( 0 .0 8% C- 1 3.3% Cr- 4.0 Ni)满足不了热裂纹和水蒸气的双重损坏 ,需要改进。在试验研究基础上开发的缓慢冷却型连铸辊用材料是耐热不锈钢堆焊合金 Super KBS( 0 .1 6% C-1 2 .9% Cr- 0 .1 % Ni- Co.Mo.V.Cu) ,同时也开发出强冷却型连铸辊用材料析出硬化不锈钢堆焊合金 W630 ( 0 .0 4 % C- 1 7.1 % Cr- 4.5 % Ni- 4.5 Cu- 0 .1 2 Nb)。本文拟叙述一下此次开发的缓冷型和强冷型用辊堆焊材料的设计思想 ,开发堆焊材料的…     

Detection of multiple hepatic micrometastases in pancreatic adenocarcinoma with a solitary liver metastasis by direct sequencing of the K-ras gene: a case report

Short-chain fructo-oligosaccharides (SC-FOS) are a mixture of oligosaccharides consisting of glucose linked to fructose units (Gfn; n = 相似文献   

20G钢非金属夹杂物的行为研究

针对某钢厂在生产20G钢初期,存在表面裂纹,低倍检验不合格的问题,对其生产过程中非金属夹杂物类型、数量、来源、尺寸及分布进行了综合分析。研究表明:正常铸坯中显微夹杂物平均总体积率0.149%,连浇坯中显微夹杂物平均总体积率为0.184%;正常坯中大型夹杂物平均含量为1.81 mg/kg,连浇坯中含量为3.31 mg/kg,其夹杂物主要来源于结晶器液面保护渣,其次中包覆盖剂和钢包渣卷入也是钢水污染的一个原因。     

Inhibitory guanine-nucleotide-binding-regulatory protein alpha subunits in medaka (Oryzias latipes) oocytes--cDNA cloning and decreased expression of proteins during oocyte maturation

We have previously shown that pertussis-toxin-sensitive inhibitory guanine-nucleotide-binding-regulatory proteins (G proteins) are involved in the signal transduction of steroidal maturation-inducing hormone (MIH) of rainbow trout (Oncorhynchus mykiss) oocytes, 17alpha,20beta-dihydroxy-4-pregnen-3-one (17alpha,20beta-DP) [Yoshikuni, M. & Nagahama, Y. (1994) Dev. Biol. 166, 615-622]. In this study, we obtained five different cDNA fragments of G protein alpha subunits from medaka (Oryzias latipes) intact ovarian follicles (three subtypes of G(i alpha), G(i alpha a), G(i alpha b) and G(i alpha c); two subtypes of G(s alpha), G(s alpha d), and G(s alpha e)). Using a newly developed extraction method for medaka oocyte RNA, we demonstrated that oocytes expressed both G(i alpha a) and G(i alpha c), but not G(i alpha b). Full-length cDNA clones for G(i alpha a) and G(i alpha c) were then isolated from a medaka ovarian follicle cDNA library. The predicted amino acid sequences of G(i alpha a) and G(i alpha c) exhibited significant similarity with G(i alpha1) and G(i alpha2) of other species, respectively. Both G(i alpha a) and G(i alpha c) possessed a specific Cys residue in the C-terminal region that was the site for ADP-ribosylation by pertussis toxin. G(o alpha), another G protein that is ADP-ribosylated by pertussis toxin, was not detected in oocytes, although it was expressed in brain tissue. Western blot analyses using a specific antibody against G(i alpha1) and G(i alpha2) subunit proteins revealed that in both medaka and rainbow trout G(i alpha) subunit protein (40 kDa) contents were abundant in plasma membranes of postvitellogenic immature oocytes, decreased in mature oocytes, and were absent in ovulated eggs. Furthermore, specific 17alpha,20beta-DP binding to plasma membranes was higher in postvitellogenic immature oocytes than in ovulated eggs. Taken together, these results suggest that G(i alpha a) and/or G(i alpha c) may be involved in the transduction of the signal from 17alpha,20beta-DP receptors during oocyte maturation of fish oocytes.     

Contribution to the prenatal diagnosis of congenital cardiopathies

After concluding a local teaching program to obstetric echographists about prenatal diagnosis of congenital heart disease (CHD), we compared 2 periods of activity in fetal echocardiography, that before, lasting 3 and one half years (G.I) and the other 6 months after (G.II). During the second period 20 newborn consecutively admitted with CHD (G.III) were also studied. Teaching program protocol for the 10 district hospitals visited is described. The results show a rise from 25 to 58 foetus per month observed, comparing the two periods, being 4 and 7% respectively those referred with suspicion of CHD, and 54 and 33% the obstetric accuracy. Total incidence of CHD was 4,2%, 41 in G.I and 6 in G.II. Types of CHD, treatment and evolution are described, being the mortality 68 and 50% respectively. Of the 20 newborn from G.III, 90% had no prenatal diagnosis of CHD, being 30% high risk pregnancies. Mortality in this group was 20%, 50% in the newborn from high risk pregnancies; eight newborns were operated on without mortality, 5 to aortic coarctation and 2 with arterial switch for transposition. It is concluded the necessity of continuing teaching programs so that prenatal diagnosis of CHD may improve and the care of the newborn may so be anticipated and ameliorated.     

Mechanism of 17 alpha-hydroxylase/17,20-lyase--an initial geometric perspective for the lyase of the C(17)-C(20) bond of C21 steroids

A biosensor based on an H+ ion sensitive field effect transistor (H+(-)ISFET) and penicillin G acylase has been developed. The response time of the sensor to different concentrations of penicillin G was 30 s. In a 20 mM phosphate buffer at pH 7.0, the linear range of the calibration curve was from 0.5 to 8 mM. The coefficients of variation for three samples with 20 repeated measurements were below 5%. Stability of the sensor could reach about 6 months and more than 1000 runs were performed without a significant decrease of the output value. The sensor was tested for measurement of the penicillin G content in penicillin fermentation both. Forty samples with low and high concentrations of penicillin G were chosen for the correlation test. The values assayed by the sensor method were compared with the values assayed by HPLC method, the correlation coefficient (r) was 0.9944 and the regression equation was y = 1.034X - 2083.7, respectively. The different measuring methods are discussed in the text.     

Three-dimensional folding of an RNA hairpin required for packaging HIV-1

An NMR-based structure is presented for a 20 mer hairpin model of the SL3 stem-loop from the HIV-1 packaging signal. The stem has an A-family structure. However, the GGAG tetraloop appears to be flexible with the second (G10) and fourth (G12) bases extruded from the normal stacking arrangement. The A-base (A11) occupies a cavity large enough for it to jump rapidly between stacking upon G9 (in the loop) and G13 (from the base-pair adjacent to the loop). The H-bonding loci of G10, A11, and G12 are unoccupied in the free RNA structure. The loop should be easily adaptable to binding by the HIV-1 nucleocapsid protein or loop receptors.     

Deuteriation of sugar protons simplify NMR assignments and structure determination of large oligonucleotide by the 1H-NMR window approach

The concept of the 1H-NMR window has been developed and examined through a comparative study of NOESY spectra of a self-complementary Dickerson's dodecamer (I) [5'd(5C6G7C8G9A10A11T12T13C-14G15C16G)2(3')], a self-complementary 20-mer (II) [(5'd(1C2G3C4G5C6G7C8G9A10A11T12T13C14G15C16G17C18G19C20G)2(3')] in which the core part consists of the same Dickerson's dodecamer sequence with the flanking CGCG residues at both 3' and 5'-ends, and the partly-deuteriated (shown by underlined CGCG residues at both 3' and 5'-ends) analogous duplex (III) [5'd(1C2G3C4G5C6G7C8G9A10A11T12T13C14G15C16G17C18G19C20G)2(3')] in which the core 5C to 16G part (i.e. 1H-NMR window) consists of the natural Dickerson's dodecamer sequence. A comparison of their NOESY spectra clearly demonstrates that the severe overlap of proton resonances in the larger DNA duplex (II) has been successfully reduced in the partly-deuterated duplex (III) as a result of specific incorporations of the sugar-deuteriated nucleotide residues in the latter [stereospecific > 97 atom % 2H enrichment at H2', H2' and H3' sites, approximately 85 atom % 2H enrichment at H4' and approximately 20 atom % 2H enrichment at H1' (see refs. 10 and 11) in the 20-mer duplex (III)]. These simplifications of the resonance overlap by the deuteriation approach have enabled unequivocal chemical shift assignments and extraction of the quantitative NOE data in the 1H-NMR window part of duplex (III). A comparison of the 12-nucleotide long 1H-NMR window in (III) with that of the 12-mer duplex (I) also shows the scope of studying the changes in conformation and dynamics of the core 12-mer region in (III) which result from the increase of molecular weight due to the DNA chain extension. It is noteworthy that such a study is clearly impossible for the natural 20-mer (II) because of the inherent problem of the overlap of resonances.     

Effect of a pipe-steel killing technology on the composition and number of nonmetallic inclusions

Pipes made from steels 19G, 17GS, 17G1S, 10G2FBYu, 13G1S-U, and 20KT of various manufacturers and technologies are studied. Electron microprobe and fractional gas analyses are used to determine the main types and number of nonmetallic inclusions (NIs). The effect of a modification procedure on the oxidic cleanness of steel 20KT (produced at JSC “Volzhskii Pipe Works”) is studied. The use of a silicocalcium-filled wire is shown to increase the total contamination of the steel by nonmetallic, in particular, calcium aluminate and magnesium spinel inclusions, which are conditionally related to corrosion-active nonmetallic inclusions (CANIs). Fractional gas analysis is shown to allow the number of oxide inclusions of various types to be accurately determined in pipe steels. No correlation is found between the volume fraction of oxide inclusions determined by fractional gas analysis and the number of CANIs determined by a metallo-graphic method.     

Intergenerational continuity in parenting quality: The mediating role of social competence.

Prospective studies of intergenerational continuity in parenting quality remain scarce, with little attention given to the potential role of social competence as a mediator of continuity. This study examined social competence as a mediator in the pathway from 1st generation (G1) to 2nd generation (G2) parenting quality. A normative sample of children and their parents were assessed in childhood, and again 10 and 20 years later. Parenting quality of G1 parents was assessed at each time point with multiple informants, as was G2 social competence. G2 parenting was assessed at the 20-year follow-up for those who were parents. The mediational role of social competence in G1 to G2 parenting quality was tested via nested path analytic models, accounting for continuity and cross-domain relations. Social competence mediated the intergenerational relation of parenting quality; results were invariant across gender and ethnic minority status and were unchanged after controlling for age, IQ, socioeconomic status, rule-abiding conduct, and personality (i.e., constraint). The authors discuss results regarding developmental theories of close relationships and the potential for cascading benefits within and across generations from interventions to improve G1 parenting or G2 social competence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)