Results 91 to 100 of about 26,640,317 (249)
Shiyou jixie, 2015 鉴于国内外运用多相流数值模拟方法对水力喷射工具冲蚀研究有待深入的现状，基于多级水力喷射工具单级喷枪，采用颗粒碰撞的欧拉拉格朗日离散相模型，对水平井水力喷砂射孔过程进行流场分析及冲蚀速率计算。分析了单级喷枪上、下游喷嘴流场分布的不均匀性，以及这种不均匀性导致的工具内部各个喷嘴冲蚀速率的差异。分析结果表明，水力喷砂射孔过程中，水力喷射工具单级喷枪上、下游喷嘴流场呈现不均匀性，上游喷嘴单位时间通过的液体多于下游喷嘴，下游喷嘴的砂浓度高于上游3个喷嘴 ...
doaj
FEBS Letters, EarlyView.Plasma membranes contain dynamic nanoscale domains that organize lipids and receptors. Because viruses operate at similar scales, this architecture shapes early infection steps, including attachment, receptor engagement, and entry. Using influenza A virus and HIV‐1 as examples, we highlight how receptor nanoclusters, multivalent glycan interactions ...
Jan Schlegel, Christian Sieben
wiley +1 more source
Shiyou jixie, 2015 针对目前气井涡流携液机理和效率认识不清，现场工程设计与分析主要依据经验，影响应用效果等问题，运用AutoCAD和Fluent流体模拟软件，建立了涡流工具气液两相流场模型，分析了气液混合物通过涡流工具前后的流动轨迹、流型变化特征和携液效率变化规律。研究结果表明，涡流工具将气液两相雾流转换为螺旋环流，液体以液膜形式沿管壁螺旋向上流动，而气体在油管中心以更高的速度流动。这种流态能够降低流动过程中的压力损失24.3%，提高流体速度13.5%，减小持液率3.3%，减弱气液两相之间的滑脱，提高气体携液能力 ...
doaj
FEBS Letters, EarlyView.Embryo‐like structures (stembryos) are an innovative tool, but they are hindered by experimental variability and limited developmental potential. DNA methylation is crucial for mammalian development, but its status in stembryo models is poorly characterized.
Sara Canil +4 more
wiley +1 more source
Shiyou jixie, 2015 介绍了用重力加速度传感器测量重力工具面的原理，提出了一种提高精度和稳定性的小井斜重力工具面动态测量方法，搭建了基于石英加速度计的重力工具面动态测量系统，并针对现有自动垂直钻井系统在随钻状态下受到振动和冲击信号干扰测量精度下降和测量结果不稳定的问题，提出在常规硬件滤波的基础上，提高采样频率来反映信号原貌，加以多种数字信号处理方式以提高重力工具面动态测量精度。通过振动台的随机振动试验和井下实钻数据振动试验结果显示，测量精度和实时性均有提高。通过试验验证了该重力工具面测量方法和信号处理方式行之有效 ...
doaj
pH‐mediated activation of the lysosomal arginine sensor SLC38A9
FEBS Letters, EarlyView.Cells monitor nutrient levels via the lysosomal transporter SLC38A9 to activate the mechanistic target of rapamycin complex 1 (mTORC1). This study reveals that SLC38A9 function is regulated by pH. We identified histidine 544 as a critical pH sensor that undergoes conformational changes to control amino acid efflux from lysosomes; therefore, it ...
Xuelang Mu, Ampon Sae Her, Tamir Gonen
wiley +1 more source
Shiyou jixie, 2015 根据流体力学理论，以连续性方程和N-S方程为控制方程，利用计算流体力学理论对不同偏心度的赫巴流体环空流动进行系统的数值模拟，得到了偏心度的变化对于流场特性及摩阻压耗特性的影响规律，发现随偏心度不断增大，环空宽间隙处的流速剖面先不断增大，在达到临界最大流速剖面后又逐渐减小，其中先不断增大的规律依据已有研究且得到证实；运用涡黏理论对井壁、钻柱外壁及流体内部的应力-应变关系进行分析，揭示了达到临界流速剖面前、后流场内部不同的力学状态，以及随偏心度增大摩阻减小趋势不同的原因 ...
doaj
FEBS Letters, EarlyView.Ascidian Ciona larvae initially show strong clockwise tail twisting, which is largely corrected during development. However, a small residual twist remains. This study shows that organized helical myofibrils in tail muscles mechanically stabilize this residual asymmetry, preventing complete restoration of bilateral symmetry and revealing how embryos ...
Yuki S. Kogure +3 more
wiley +1 more source
Shiyou jixie, 2014 水下采油树油管悬挂器是水下生产系统的关键设备，其密封性能关系到深水石油开发的成败。介绍了国外ABB Vetco Gray公司、Cameron公司、DrilQuip公司和FMC公司的水下油管悬挂器密封技术，阐述了密封作用的原理，并对国外公司不同类型密封圈的性能进行了对比。同时分析了水下油管悬挂器密封的关键技术，总结了高温、高压、强腐蚀环境下油管悬挂器密封的发展趋势，最后指出金属与非金属组合的密封形式是当前水下油管悬挂器密封设计的主流，PTFE和PEEK等密封材料的发展将大大增强悬挂器的密封性能 ...
doaj
Biophysical approaches for studying viral entry
FEBS Letters, EarlyView.Viruses infect all living organisms and have been responsible for major epidemics and pandemics. Their ongoing evolutionary battle with host defenses creates a constant need for improved tools to study viral behavior. Advancing methods to probe viral attachment, fusion, and genome release deepen our understanding of how infections begin and support the
Inbar Yosibash, Raya Sorkin
wiley +1 more source