C50 级混凝土冬季施工技术探讨

介绍了应用在预应力砼Ｔ型梁的Ｃ５０级砼的冬季施工配制措施，并给出了－１０℃条件下的砼有效配合比及冬季４５℃±５℃蒸汽养生法措施。     

Off-Optimum Cure of Aerospace Epoxy Adhesives

Four epoxy film adhesives used in aircraft manufacture and repair have been examined to establish the effect of deviation from the cure cycle specified by the manufacturer. In addition to the variation of the cure cycle, two surface preparations of the aluminium adherends (chromic acid etch or grit blast followed by silane treatment) were evaluated. Thermal analysis was used to examine the cure envelope of the adhesive, and its extent of cure and glass transition temperature. The adhesive properties were assessed by shear strength (in both single lap joints and in Iosipescu configuration), durability (Boeing wedge test) and chemical resistance to selected aggressive fluids. The sensitivity of the performance of a particular adhesive to offoptimum cure conditions depends on its composition and needs to be determined, not predicted.     

Study on high-strength composite portland cement with a larger amount of industrial wastes

It is one of important measures for the sustainable development of cement industry to utilize industrial wastes. High-strength composite portland cement with a large amount of granulated blast furnace slag (GBFS), fly ash and limestone was prepared by separate grinding method, optimizing gypsum and using activators. The total amounts of blending materials are between 45% and 65% and the strength grades of cements reach 525 or even 625 according to Chinese national standard for composite portland cement. Besides setting time and strength, the hydration heat, drying shrinkage and sulfate resistance were also determined.     

牵引链强度的模糊可靠度计算方法研究

利用最大应力和最小极限应力的概念 ,建立了机械强度的模糊可靠性设计理论 ,依据此理论 ,对刮板输送机牵引链强度的模糊可靠性设计问题进行了研究 ,并附有应用实例。     

碳纤维表面处理对铝电解用硼化钛阴极涂层性能的影响

硼化钛阴极涂层是铝电解用可润湿性阴极材料中的一种，具有优良的抗钠渗透性和对铝液润湿性，可以有效地延长铝电解槽寿命。碳纤维是硼化钛涂层材料的增强剂之一．对硼化钛阴极涂层的性能影响很大。本文研究了不同工艺的液相碳纤维表面氧化处理法对硼化钛阴极涂层抗拉强度和粘接强度的影响。采用PTIR检测碳纤维处理后表面含氧基团的变化，寻找影响硼化钛阴极涂层性能的原因，从而达到最有效地提高TiB2阴极涂层抗拉强度和粘接强度的目的。结果表明，采用工艺(1)(10％HNO3，80℃、恒温5min．超声波、5min)对碳纤维进行表面处理最合理，处理后碳纤维表面含氧基团的含量最高．用其制备硼化钛阴极涂层的抗拉强度、粘接强度最大。     

塑钢包装箱材料贮存寿命预测

用热老化箱对4种塑钢包装箱用材进行了为期1个月的热老化试验，以材料的冲击强度作为判据指标，通过回归处理外推得到其常温下的贮存寿命预测评估结果。     

岩石龟裂系数法在火山岩裂缝储集层预测中的应用

 本文针对辽河东部凹陷油燕沟中生界火山岩的具体特征，采用纵波波速的比值——“龟裂系数”裂缝分析法［1,2,3］，研究了火山岩裂隙发育程度。综合龟裂系数裂缝分析及其他方法发现，该区中生界火山岩有效储集层的测井相特征主要表现为低密度、低中子、高声波时差和高伽马值等特征。此法的关键在于根据不同火山岩的岩性，选用合适的岩石骨架参数，在此基础上利用测井约束地震反演计算火山岩的层速度，进而计算出龟裂系数，然后根据已钻至火山岩井孔的测井相特征编制出火山岩预测厚度图。     

Development of sealing compositions with nanostructure iron-based fillers

The possibility of utilizing nanopowders of iron and Fe-Co-Ni produced bu a thermochemical method in the fabrication of sealing composition materials is investigated. It is established that such hermetic sealing composition materials function reliably under extremal conditions and guarantee elevated strength of adhesion to the surface of the metal and high corrosion and temperature stability. __________ Translated from Poroshkaya Metallurgiya, Nos. 3–4(448), pp. 112–117, March–April, 2006.     

Mycological and physical parameters for selecting suitable packaging material for pre- and post-irradiation storage of cereal grains in Ghana

Owing to the rough warehouse handling of storage sacks in tropical areas in Africa, a suitable storage sack should not support de novo growth of fungal spores because this would reduce the tensile strength of the packaging material and act as a springboard for infecting grain contents. This paper reports the effect of activity of saprophytic fungi on the tensile strength of jute and woven polypropylene sacks. New woven polypropylene sacks carried lower levels of fungal spores (1.3×10¹ cfu/72 cm²) than jute sacks (3.0×10³ cfu/72 cm²). The natural mould penetration and growth was examined on sections (4×5 cm) of both jute and woven polypropylene after previous incubation at relative humidities of 55, 60, 65, 70, 75, 80, 90 and 95% for 10 weeks by placing them on Sabouraud's Agar. There was a significant difference (P = 0.05 level of significance) between the higher penetration of mould growth on jute sacks and that obtained on woven polypropylene sacks. Saprophytic fungi (Aspergillus candidus, A. flavus, A. fumigatus, A. niger, A. japonicus, A. parasiticus, A. ustus, Fusarium oxysporium, F. moniliforme, Penicillium verucosum var. cyclopium, Rhizopus oryzae and Trichoderma viride) isolated from jute sacks reduced tensile strength, measured by an Instron Model 1026, by 50–75% after 10 weeks at 90% R.H. Same fungal species on woven polypropylene sacks did not alter the tensile strength. Woven polypropylene sacks did not absorb moisture whilst the moisture content of jute sacks increased by 5.3–6.0% in 10 weeks at 90% R.H. with concomitant increase in mould and yeast counts by 1–2 log cycles. Evidence is presented to show that there was a positive correlation between the final mycoflora on jute sacks and loss in tensile strength. No correlation, however, was found between the total aerobic bacteria on jute sacks and the concomitant reduction in tensile strength. Fungi therefore play a major role in the reduction of tensile strength of jute sacks. Sterilization by gamma irradiation (8.0 kGy) of jute and woven polypropylene sacks did not affect their intrinsic tensile strength. Woven polypropylene sacks therefore have many microbiological and physical advantages over the traditional jute sacks to merit their use for grain storage in tropical areas like Ghana.     

On-line H NMR spectroscopic investigation of hydrogen bonding in supercritical and near critical CO2–methanol up to 35 MPa and 403 K

On-line NMR spectroscopy can beneficially be applied to studies of supercritical and near-critical fluids as an alternative to optical spectroscopy. Up to now high pressure NMR experiments are predominantly accomplished using custom made NMR batch reactors. The authors present a novel high pressure cell with displacement plunger for on-line NMR experiments on compressible fluids which can be used in conjunction with commercially available SCF NMR flow probes. The on-line technique offers advantages compared to stopped flow techniques such as enhanced control of mixture composition and reaction parameters as well as the facility of engagement into the reaction. The new apparatus is used for NMR studies on hydrogen bonding of methanol in near critical and supercritical carbon dioxide up to 403 K and 35 MPa for which data on the chemical shift of the hydroxyl group and methyl group are reported and interpreted.