COPD模型大鼠急性加重期诱导肝脏损害的实验研究

目的：观察脂多糖（LPS）致COPD模型大鼠急性发作时对肝脏的影响。方法：清洁级健康雄性Wistar大鼠24只,随机平均分为正常组,COPD模型组及COPD急性加重组。采用改良熏香烟加气管内注脂多糖的方法建立COPD模型,造模结束后第2天滴加脂多糖建立COPD急性加重模型。6h后进行肝功能检测,RT-PCR法检测肝肺组织γ—GCSmRNA的表达,观察肺肝病理及超微结构改变。结果：与正常组比较,COPD模型组大鼠碱性磷酸酶（AKP）无统计学意义,谷丙转氨酶（ALT）升高（P〈0．05）,ALB下降（P〈0．05）,总结合胆红素（TBIL）明显升高（P〈0．01）;与正常组比较,COPD急性加重组大鼠白蛋白（ALB）明显下降（P〈0．01）,ALT、TBIL、AKP均明显升高（P〈0．01）。与COPD模型组比较,COPD急性加重组AKP、AIJT均升高（P〈0．05）,ALB下降（P〈0．05）,TBIL明显升高（P〈0．01）。与正常组比较,COPD模型组肺组织中γ—GCSmRNA表达水平显著增高（P〈0．01）,而肝组织中基因表达水平没有明显变化;COPD急性加重组肝肺组织中γ-GCSmRNA表达水平均显著增高（P〈0．01）,且与COPD模型组比较有显著差异（P〈0．01）。肺肝两脏病理及超微结构均发生了变化。结论：COPD模型大鼠急性加重时可进一步诱导肝脏损害。     

分割放射中小肠上皮细胞亚致死性损伤修复的特点

本文研究小鼠小肠上皮细胞分割照射时亚致死性损伤修复的特点。定量测定每次照射后修复的剂量(D_R值)。结果见到D_R的大小与照射的剂量有关。但每次照射后修复的百分比(F_R)均为50％左右。STRANDQVIST曲线指出其修复斜率为0.25。这和皮肤等组织相似。应用线性—平方概念(L-Q模式)分析了细胞生存数为20时的等效总剂量,求得小肠上皮细胞的α/β比值为10.7Gy。     

药物动力学-药效动力学联合模型的研究概况

药物动力学(pharmacokinetics,PK)-药效动力学(pharmacodynamics,PD)联合模型是将PK与PD紧密结合,用于研究药理效应随时间变化规律的一种模型。此模型可应用于药物开发的临床前和临床试验的各个阶段。本文介绍了该领域的一些概念和国内外研究概况,包括:效应室理论和Hill’s方程,PK-PD联合模型的属性,常用计算程序,应用及国内外研究实例。     

Experimental and Numerical Study on Uniaxial Compression Failure of Concrete Confined by Nylon Ties

The developments in the cisvil engineering fields have led to an increased demand for structural reinforcements. Therefore, designing an effective, green, convenient, and low-cost reinforcement method is considerably important. Nylon ties have high strength and good heat resistance, and they can retain good tensile properties after high-temperature cooling. Further, they are inexpensive and can be recycled. Thus, they are considered suitable for structural reinforcement engineering. In this study, the core concrete was reinforced by the active confinement of prestressed nylon ties. A uniaxial compression test was performed to evaluate the reinforcement effect of the preload generated by the high-temperature cooling of the tie rod on the core concrete. The results show that nylon ties can effectively improve the mechanical properties of the core concrete. Combined with numerical simulation technology, a damage model of a confined concrete column (CC) was established, and the damage evolution law of CC under uniaxial axial compression was analyzed. Combined with numerical simulation and experimental research, the effectiveness of nylon tie reinforced concrete and the reliability of the damage model were verified, providing a reference for research on engineering reinforcement.     

心搏骤停后脑复苏研究的动物模型

目的 建立一种新型简便的心跳骤停后脑复苏研究的动物模型。方法 选用清洁级雄性Sprague Dawley（SD）大鼠40只,采用窒息合并冰氯化钾停跳液致大鼠心跳骤停,5min后开始心肺复苏。记录基本生命体征变化、发生循环停止时间（TCA）、自主循环恢复时间（TROSC）、72h存活率,复苏后不同时间点（3、6、12、24、48、72h）神经功能评分（NDS）,观察复苏后3h和72h透射电镜下皮层超微结构改变。结果 造模后大鼠迅速发生循环停止,TCA和TROSC分别为（137．3±10．2）s,（64．4±9．3）s,复苏成功率87．5％,72h存活率为80％。NDS在复苏后3h时最低,以后NDS渐趋好转。血浆丙二醛（MDA）水平显著升高,在72h略有回降,但仍高于造模前（P〈0．01）。电镜显示复苏后3h脑损害最严重,72h逐渐减轻。结论 这一模型操作简单且结果稳定。     

Microstructure Evolution and Deformation Mechanisms of As-Cast Antibacterial Ti6Al4V-5Cu Alloy for Isothermal Forging Process

The hot workability behavior of antibacterial Ti6Al4V-5Cu alloy was investigated using a hot compression experiment in the temperature range of 790–1040 °C and strain rate of 10⁻³–10 s⁻¹ with a strain of 0.4. The deformation behavior of the alloy was characterized by Gleeble 3800 compression experiment, and the relationship among deformed microstructures and deformation parameters was established. The deformations of Ti6Al4V-5Cu alloy were temperature and strain rate-dependent. Higher temperature and lower strain rate made power dissipation efficiency (η) increase and reach 89%. The activation energies (Q) in the dual-phase (α + β) and single β phase regions were calculated as 175.43 and 159.03 kJ mol⁻¹, respectively. In the dual (α + β) phase region, with an increase in strain rate, flow-softening behavior was dominated, however in the single β phase region such as processing at 940 °C. Flow stress increased slightly in which work-hardening behavior was dominated (especially between strain rates of 10⁻³–1 s⁻¹). The deformation at various conditions exhibited different stress-strain profiles, providing an insight that work hardening and flow softening coexisted in Ti6Al4V-5Cu alloy. The relative intensity of oscillatory change in flow stress profile decreased as the strain rate decreased. The hot workability of Ti6Al4V-5Cu alloy was also accessed from the viewpoint of the sub-grain structure.     

Possibility to Use Short Sawn Timber in the Production of Glued Laminated Beams

Numerous studies have shown that the geometry of micro-joints significantly affects the strength of the so joined timber element. The bending strength increases by creating a larger bonding area by increasing the length of the wedge joint. Although this type of joint has been successfully used for many years, it can still be troublesome to make. For these reasons, the present study investigated an easy-to-fabricate wedge joint, which we folded during the beams’ formation and glued with the same adhesive as the individual lamellas. Although the research has not fully answered all the questions relevant to both scientific and technological curiosity, it indicates the great potential of this solution. Following the principle adopted in the ongoing wood optimisation work, we concluded that the beams of the target cross-section should be produced, and it should only be possible to cut them to a certain length. In this approach, we only removed defects at critical points for the beam structure and, in this way, up to 30% of the timber processed could be saved or better utilised.     

Determination of the Tool–Chip Contact Length for the Cutting Processes

The thermomechanical interaction of the tool with the chip in the most loaded secondary cutting zone depends on the contact length of the tool rake face with the chip. Experimental studies of the dependency of the contact length on the cutting speed, the undeformed chip thickness, and the tool rake angle, performed by the optical method, are used for comparison with the contact length obtained by the FE modeling of the orthogonal cutting process. To determine the parameters of the constitutive Johnson–Cook equation, which serves as a material model of the FE cutting model that has a predominant influence on the contact length, a software-implemented algorithm was developed. This algorithm is based on determining the generalized parameters of the constitutive equation through finding the intersection of these parameter sets. The plurality intersection of the parameter sets of the constitutive equation is determined by means of the design of experiments and refined by subsequent multiple iterations. The comparison of the contact length values, obtained by simulating the cutting process using the generalized parameters of the constitutive equation as a material model with their experimental values, does not exceed 12% for a wide range of cutting speeds and depths of cut, as well as for the tool rake angle.