火灾后预应力混凝土连续板力学性能试验与分析

完成了7块火灾后两跨无黏结预应力混凝土单向连续板受力性能试验.基于试验结果,拟合出火灾后预应力混凝土连续板中无黏结筋剩余应力、极限应力的计算公式,提出了火灾后预应力混凝土连续板正截面承载力计算公式.根据火灾下温度场分布沿板厚方向将截面分条带,引入火灾后钢筋、混凝土本构关系,基于截面轴力、弯矩平衡,获得了火灾下预应力混凝土板任意截面的弯矩-曲率关系全曲线.基于支座变形协调方程,可用割线刚度法对支座反力进行迭代求解,计算板在外荷载(曲率荷载)与支座反力共同作用下的弯矩、挠度和支座位移,进而对截面曲率积分可求得连续板的变形.试验结果表明:初始有效应力越高、受火时间越长,火灾后连续板预应力钢丝应力损失越严重;保护层厚度越小、受火时间越长、荷载水平越大,火灾后板跨中截面承载力降低幅度越大;受火时间越长、荷载水平越大,板中支座截面承载力降低幅度越大.     

X trisomy in a sterile mare

This report concerns the cytogenetic analysis, using both C‐banding and fluorescence in situ hybridisation techniques, of a sterile mare. Results obtained revealed a 2n = 65, XXX condition with no sign of mosaicism. The work supports the suggestion that X trisomy, rare in horse, causes infertility in mares and is not associated to other clearly visible phenotypic features.     

先张法预应力混凝土空心板施工质量监控分析

嵩待高速公路七合同段K62＋111（3—20）桥为先张法预应力钢筋混凝土空心板梁桥。本文以此为切入点，详细阐述二横梁槽式台座内预应力钢绞线单股逐根张拉设备及夹具选用、铜绞线张拉前的准备工作、张拉的步骤和方法、钢绞线放张和切断的原则及顺序等。分析先张法预应力钢筋混凝土空心板在施工过程中台座、张拉设备、控制应力及张拉程序等质量控制问题。就现场施工过程中出现的钢绞线磨损严重、夹片损坏严重、钢绞线实际伸长值达不到要求、钢筋混凝土横梁开裂、空心板预拱度无法达到要求等这些关键性问题的解决补救措施进行简要分析。     

20CrMnMo钢稀土渗碳研究

采用稀土渗碳工艺对20CrMnMo钢进行渗碳处理,研究了渗层增厚的动力学、渗碳层组织和性能。结果表明:稀土渗碳层中沉淀析出了大量弥散分布的粒状碳化物,淬火后表层组织为针状马氏体、大量细小颗粒碳化物、少量残余奥氏体。渗碳层的硬度与传统工艺相比提高了10%,耐磨性提高了32%,接触疲劳寿命也有大幅提高。     

Rapid X‐ray spectrographic determination of major element homogeneity in Mazama pumice

Abstract

Permanent powder mounts were prepared for X‐ray spectrographic analysis by molding bakelite powder at 24,000 psi and heating to 110C. Spraying with clear acrylic resin maintains surface permanency for non‐clayey samples. Standard curves for Si, Al, Fe, K, Ca, and Ti prepared with USGS and NBS rock powders were used to determine that two distinct textural layers of Mazama pumice had similar major element contents. Ground pumiceous lapilli from the weathered AC horizon (20–30 cm depth) had 4% less Ca, 4% less Si, 8% less K, 9% more Ti, 12% more Al, and 16% more Fe than unweathered pumice in the C1 and C2 horizons.     

Late season foliar fertilization of beans with NPKS: Effects of cytokinins,calcium and spray frequency

Abstract

One to two foliar applications of NPKS solutions enhanced yields from 10–40% when applied to pot grown bean plants (Phaseolus vulgaris, var. Bulgarian) during the seed filling period. Further spray applications had progressively more negative effects on yields. Addition of calcium ions or cytokinin to the spray treatments did not give further yield increases. Addition of an organo‐silicone surfactant (L77) to the spray solution gave higher yield increases than those obtained by adding a carbohydrate based surfactant (Tween 80). Percent N P and K contents of the bean seeds were inversely related to yields suggesting that the rate of supply of these minerals to the seeds was not limiting production; the results support the idea that leaf integrity was one of the main factors affected by late season N P K S sprays, and that this in turn affected yields.     

Effects of lime and applied Mn on plant Mn,growth and chlorophyll concentration of ‘Tifway II’ bermudagrass

Abstract

A glasshouse study was conducted to determine effects of lime and Mn applied to three Florida soils on plant Mn, growth, and chlorophyll concentration of ‘Tifway II’ bermudagrass (Cynodon dactylon x Cynodon transvaalensis). Four replications of three lime rates (0, 1000, and 2000 mg CaCO₃/kg as dolomite and Ca(OH)₂ for Astatula fine sand (Typic Quartzipsamment, hyperthermic, uncoated) and Pompano fine sand (Typic Psammaquent, siliceous, hyperthermic); 0, 2000, and 4000 mg CaCO₃/kg as dolomite and Ca(OH)₂ for Myakka fine sand (Aeric Haplaquod, sandy siliceous, hyperthermic) and three Mn applications (none, 10 mg Mn/kg as MnSO₄, and 5 mg Mn/kg as MnEDTA) were used in a randomized, complete block, factorial design. A wide range of plant Mn concentrations existed across treatments for each soil. Differences in plant Mn concentration did not cause significant differences in growth or chlorophyll concentration. The critical plant Mn concentration was not reached, but it appeared to be below 20 mg Mn kg for bermudagrass. Models for prediction of plant Mn concentration using soil pH and extractable soil Mn (Mehlich I, Mehlich II, DTPA‐TEA) were obtained. The applications of MnSO, and MnEDTA each resulted in increased plant Mn under acidic soil conditions. Neither Mn application resulted in increased plant Mn concentration in grass grown on Pompano fine sand with soil pH values of 7.0 or above.     

面向河北钢铁企业创新发展信息服务体系研究

以河北钢铁企业为例,依托高校图书馆的资源、人才、技术等优势,构建了以信息资源建设的可持续性为保障,以地方高校资源共享平台为技术支撑,通过信息资源统一检索,实现一站式服务的＂三位一体＂信息服务体系,并探讨了该体系具体的实施策略。     

次氯酸钠加吐温80对马铃薯外植体的灭菌比较试验

升汞是灭菌效果非常好的一种灭菌剂,但它是有剧毒的重金属盐灭菌剂,对人畜有极强的毒性,且容易污染环境。为了寻找对马铃薯外植体安全有效的灭菌剂,试验通过对马铃薯外植体,用次氯酸钠溶液与添加吐温80的次氯酸钠溶液不同浓度、不同时间处理后,与升汞处理相比较成苗率、感染率和褐化率。试验结果表明,加2%吐温80的11%次氯酸钠溶液处理30 min,对马铃薯外植体的灭菌效果最好,其成苗率高于0.1%升汞处理后的成苗率;加2%吐温80的13%次氯酸钠溶液处理20 min后的灭菌效果也较好,成苗率略低于0.1%升汞处理后的成苗率。     

夏季利用全株玉米青贮混合日粮在组合式轻钢结构羊舍育肥鲁西黑头羊效果试验

利用全株玉米青贮配制鲁西黑头肉羊全混合日粮(TMR),在研制的实用专利轻钢结构组合式羊舍进行育肥,结果肉羊平均日增重达到237 g以上,试验组间增重差异不显著(P0.05)。以试验3组日粮配方实用经济效果最好,可优先在肉羊育肥生产中推广。研制的组合式轻钢结构羊舍不仅投资少、结构简单、组装拆卸简便,而且饮水、喂料方便,通风性好,适宜于夏季肉羊育肥生产。