Spider-net within the N6, PVA and PU electrospun nanofiber mats using salt addition: Novel strategy in the electrospinning process

Electrospun nanofibers are promising candidates in the nanotechnological applications due to the advantages of the nanofibrous morphology. Therefore, many attempts were reported to modify the electrospun mats to gain more beneficial properties. In the present study, we are introducing a strategy to synthesize electrospun polymeric nanofiber mats containing spider-net binding the main nanofibers. Addition with long stirring time of a metallic salt having tendency to ionize rather than formation of sol–gel in the host polymer solution reveals to synthesize a spider-net within the electrospun nanofibers of the utilized polymer. Nylon6, polyurethane and poly(vinyl alcohol) have been utilized; NaCl, KBr, CaCl₂ and H₂PtCl₆ have been added to the polymeric solutions. In the case of nylon6 and poly(vinyl alcohol), addition of the inorganic salts resulted in the formation of multi-layers spider-network within the electrospun nanofibers mats. The synthesized spider-nets were almost independent on the nature of the salt; the optimum salt concentration was 1.5 wt%. The metallic acid led to form trivial spider-nets within both of nylon6 and poly(vinyl alcohol) nanofibers. In a case of polyurethane, few spider-nets were formed after salt addition due to the low polarity of the utilized solvents. According to TEM analysis, the synthesized spider-net consisted of joints; the later issued from the main nanofibers at Taylor's cone zone. The spider-net improved the mechanical properties and the wetability of the nylon6 nanofiber mats, accordingly a mat having amphiphilic feature has been prepared.     

考虑启动压力梯度和注采比的不稳定压力动态特征

建立了考虑启动压力梯度和注采比因素的均质油藏数学模型。用数值方法对其求解。绘制并分析了不稳定压力动态典型曲线。研究表明,启动压力梯度和注采比对压力动态影响较大。对于开井压力降落情况,注采比小于1时,压力及其导数曲线均上翘,生产压差增大;注采比大于1时,压力及其导数曲线均下掉,生产压差减小。对于关井压力恢复情况,启动压力梯度和注采比越大,井底压力恢复得就越高。在低渗透油藏的测试资料分析中,考虑启动压力梯度和注采比的影响是十分必要的。     

组合纠偏法扶正兰州白塔

通过扶正兰州白塔的成功实践，阐明了组合纠偏法的原理、方法和工艺，提出并应用共同作用原理和钢筏托换工艺，保障了古塔纠偏的安全。根据土的弹塑性理论，对纠偏参数进行了准确计算，使纠偏精度达到了以ｍｍ计的水平，取得了很好的纠偏加固效果。     

Mechanical Properties of Composites Based on Low Styrene Emission Polyester Resins for Marine Applications

Glass fibre reinforced polyester composites are used extensively for hulls and decks of pleasure boats. Boat-builders must optimise manufacturing technology, not only with respect to mechanical properties but also limiting volatile organic compounds (VOC) emissions. One way to achieve this is through modified polyester resin formulations such as low styrene content, low styrene emission or combinations of these. The resin matrix selection procedure is based on design specification (mechanical behaviour) but also manufacturing requirements and cost considerations. For this application post-cure is rarely used so it is important to optimise curing conditions. In this study the influence of the curing cycle on mechanical properties was examined first for two polyester resins. Then for one cycle (16 h at 40°C) the properties of eight resins have been determined. Significant differences in failure strain are observed, from 0.9% to 3.3%. The resins with improved VOC performance are the most brittle. The transverse tensile behaviour of these resins in composites with unidirectional glass fibre reinforcement and the limit of linearity for composites with glass mat both depend on these failure strains. These results are discussed in terms of admissible composite strains for boat design.     

关于无光釉几个问题的探讨

本文就陶瓷无光釉的定义、机理、分类、制备方法、烧成条件、色料、乳浊剂与基础釉的相互匹配等问题进行了讨论,并就无光釉无光程度的评定等问题阐述了一些个人观点。     

阀控式密封铅酸蓄电池的最新进展

通过对欧美的技术考察综述了VRLA电池近年来的最新进展情况 ,对VRLA电池的两类技术 ,即AGM技术和GEL技术进行了比较 ,认为深循环用的动力电池使用AGM技术好 ,而低功率的备用电源、UPS电池采用GEL技术有利。重点阐述了VRLA电池的工艺技术方面的国外最新动态 :( 1)板栅材料发展的三个方面 (快速冷却合金 ,轻型板栅 ,拉网板栅 ) ;( 2 )正极铅膏添加剂的作用模式 ;( 3)采用高温和膏和高温固化以增加电池容量和延长使用寿命 ;( 4 )电池组装压力和极群焊组质量对电池性能的影响等。介绍了玻璃棉隔板研究的最新动态和水平密封电池、双极性电池、卷式电池等三种新颖结构的最新进展。     

“自立号”阻滑桩的设计与建造

“自立号”是一座沉垫式可移动海上工作平台,其沉垫上的阻滑桩是根据渤海海底土质条件及风浪条件需要在原设计沉垫上增设的。阻滑桩采用了吸力桩新技术。本项工程的设计及建造均通过DnV检验。本文概要介绍阻滑桩的设计及建造方法。     

"自立号"阻滑桩的设计与建造

“自立号”是一座沉垫式可移动海上工作平台,其沉垫上的阻滑桩是根据渤海海底土质条件及风浪条件需要在原设计沉垫上增设的。阻滑桩采用了吸力桩新技术。本项工程的设计及建造均通过DnV检验。本文概要介绍阻滑桩的设计及建造方法。     

筒形件缩口成形最佳凹模锥角的确定

应用金属塑性成形理论推导出了筒形件锥形凹模缩口成形中作用于毛坯壁上的最小轴向应力的锥形凹模锥角表达式 ,并分析了摩擦因数对锥形凹模锥角的影响。     

板料马鞍形曲面的无模多点成形实验研究

在自制的多点模实验装置上对马鞍形曲面的成形进行了实验 ,并分析了实验过程中产生的压痕和失稳的分布规律及弹性垫对成形的影响 ,总结出了使用弹性垫抑制缺陷及采用逐次成形法提高板料成形极限的方法。