The C-terminus of c-ABL is required for proliferation and viability signaling in a c-ABL/erythropoietin receptor fusion protein

Activated ABL oncogenes cause B-cell leukemias in mice and chronic myelogenous leukemia in humans. However, the mechanism of transformation is complex and not well understood. A method to rapidly and reversibly activate c-ABL was created by fusing the extra-cytoplasmic and transmembrane domain of the erythropoietin (EPO) receptor with c-ABL (EPO R/ABL). When this chimeric receptor was expressed in Ba/F3 cells, the addition of EPO resulted in a dose-dependent activation of c-ABL tyrosine kinase and was strongly antiapoptotic and weakly mitogenic. To evaluate the contributions of various ABL domains to biochemical signaling and biological effects, chimeric receptors were constructed in which the ABL SH3 domain was deleted (triangle upSH3), the SH2 domain was deleted (triangle upSH2), the C-terminal actin-binding domain was deleted (triangle upABD), or kinase activity was eliminated by a point mutation, K290M (KD). The mutant receptors were stably expressed in Ba/F3 cells and analyzed for signaling defects, proliferation, viability, and EPO-induced leukemia in nude mice. When compared with the ability of the full-length EPO R/ABL receptor to induce proliferation and support viability in vitro, the triangle upSH3 mutant was equivalent, the triangle upSH2 mutant was moderately impaired, and the triangle upABD and KD mutants were profoundly impaired. None of these cell lines caused leukemia in mice in the absence of pharmacological doses of EPO. However, in mice treated with EPO (10 U/d), death from leukemia occurred rapidly with wild-type and triangle upSH3. However, time to death was prolonged by at least twofold for triangle upSH2 and greater than threefold for triangle upABD. This inducible model of ABL transformation provides a method to link specific signaling defects with specific biological defects and has shown an important role for the C-terminal actin-binding domain in proliferation and transformation in the context of this receptor/oncogene.     

水下封底混凝土与钢护筒粘结力试验

针对吊箱围堰施工中，混凝土与钢板间的粘结力无详实数据的现象，介绍了确定数据的实验模型、实验步骤，并分析了实验结果，以方便施工，指导施工。     

基于网络的智能精密压力传感器原理与应用

基于网络的压力传感器是由压敏电阻传感器、A／D转换器、微处理器、存储器和接口电路构成的，它能实现各传感器之间、传感器与系统之间的数据交换和资源共享。本文介绍PPT系列、PPTR系列网络化智能精密压力传感器的工作原理与典型应用。     

地域通信网的干扰技术研究

本文在分析地域通信网结构及组成的基础上,研究了对地域通信网实施的节点破坏、末端信息封锁、局部阻塞瘫痪等对抗方法,并使用干扰地域通信网的程度、节点干扰率、末端节点封锁率和传递信息误差率等指标对干扰效果进行评估。     

ECAP细化晶粒法的仿真与分析

ECAP(Equal Channel Angular Extrusion)方法，是实现材料纯剪切变形的有效方法。本文采用有限元（FEA）分析软件ANSYS对Al的挤压过程进行仿真与分析。分析结果表明：外切角Φ、圆角半径、试样与凹模之间的摩擦系数、凹模本身的特性（如弹性模量、泊松比等）等等，对材料的变形量都有不同程度的影响。     

Continuous and discontinuous fatigue crack growth of irradiated ultrahigh molecular mass polyethylene in saline solution at 37°C

To provide data for prosthesis design, the fatigue crack growth resistance of irradiated ultrahigh molecular mass polyethylene (UHMMPE) in saline solution at 37°C was determined from tests performed on compact tension specimens, comparable in size to the components in knee prostheses. The specimens were cyclically loaded by using a sinusoidal wave form at 1 Hz with a minimum-to-maximum load ratio of 0.1. Scanning electron microscopic fractography was used to examine the fracture surfaces. At higher stress levels, the Paris's Law was used to analyse the data, and a striation pattern with each striation corresponding to multi-cycles was observed. At lower stress levels, discontinuous fatigue crack growth was found, a phenomenon which dominated the fatigue life of the material and had not been reported previously in this material. A craze zone ahead of the crack tip was observed, which formed the discontinuous crack growth band with a length relevant to the Dugdale plastic zone length.     

混凝土大坝导温系数反演及其随时间变化的规律

随着时间的推移,混凝土的导温系数将发生变化,为了了解参数随时间的变化规律,利用原型观测资料对导温系数进行分段反演,从而拟合出大坝混凝土导温系数随时间的变化规律.     

糯扎渡心墙堆石坝心墙方案比较研究

糯扎渡工程在可行性研究阶段，比较了直心墙堆石坝和斜心墙堆石坝两种方案，分析表明，直心墙堆石坝在坝坡稳定性、坝体应力及抗震性方面均满足设计要求，且在地形地质条件、基础处理、抗震性能、施工方便性、工程造价等方面不同程度地优于斜心墙堆石坝，因此，设计最终选择直心墙堆石坝方案。     

用于大位移情形的杆系结构虚功原理

通过典型示例揭示了传统杆系结构虚功原理在“微小位移”假定下,忽略挠度的一阶导数,用二阶导数代替曲率,造成的近似计算的假象,以及引起的概念上的混乱. 论证了虚功原理实质上是一组精确的数学恒等式,只是通过定义“力”和“位移”使其中每一项都赋予了虚功的物理意义,并不存在近似的问题. 提出了用截面转角的正切值定义截面的转动位移,并将虚功中力和位移的关系描述为力不随位移拖动的模式. 由此澄清了传统虚功原理可能引起的“近似计算,只适用于小位移”的假象,使虚功原理可以抛弃小位移假定,精确地适用于大位移情形.     

γ射线对叶组织电阻变化的影响及动态分析

测试了水稻和烟草两种叶片经不同剂量的^60Co γ射线辐照处理后，组织电阻及离子外渗的动态变化情况。研究结果表明：当超过一定的剂量阈值后，随着辐照剂量的增加，两种植物的叶组织电阻均呈现先上升、后下降的变化规律；叶组织电阻的改变与离子外渗的变化趋势并不一致；用测量叶组织电阻的方法可以较灵敏地体现出植物对γ射线的动态反应情况。运用电生理学的基础理论对上述生理现象的产生原因从机理上进行了分析与探讨。