L-型钙离子通道阻断剂硝苯地平及硫酸镁对人足月妊娠子宫平滑肌收缩功能的抑制作用

目的:研究L-型钙离子通道阻断剂硝苯地平(nifedipine)、硫酸镁对人妊娠子宫平滑肌收缩功能的抑制作用及其与临产的关系.方法:剖宫产时取足月妊娠临产、未临产子宫下段平滑肌,将肌条置于组织器官浴中,加入催产素(10-9mol/L)诱发平滑肌收缩,依次加入10-8、10-7、10-6、10-5mol/L的硝苯地平或1、2、4、8、16 mmol/L的硫酸镁,通过离体肌肉等长张力测定试验,计算用药前后单位时间内子宫收缩的频率、收缩幅度及子宫收缩曲线下面积,并计算药物抑制百分比.结果:硝苯地平对催产素诱发的人妊娠子宫平滑肌收缩的抑制作用呈剂量依赖性,对临产组的抑制作用较未临产组明显减弱,两组比较差异显著(P<0.05);硫酸镁对人妊娠子宫肌收缩也有抑制作用,但临产组与未临产组比较差异不显著(P>0.05).结论:硝苯地平对临产后子宫平滑肌的抑制作用下降,可能提示临产后子宫平滑肌对硝苯地平的敏感性发生了改变;硫酸镁对人妊娠子宫肌的抑制作用与是否临产无关,提示Mg2 对子宫平滑肌收缩的抑制作用除通过钙离子通道外,可能还有其他作用机制.     

Penetration and Cratering of Steel Target by Jets from Titanium Alloy Shaped Charge Liners

In order to enlarge the crater diameter of shaped charge jet penetration into steel targets, this paper investigates the penetration and cratering characteristics of steel targets by shaped charge jets from titanium alloy liners. Titanium alloy shaped charge liners are prepared separately with mechanical processing and selective laser melting (SLM), and pulsed X-ray radiography is used to identify jet formation characteristics. Jet formation is numerically simulated by AUTODYN-3D, and steel target penetration tests are carried out at a short jet stand-off distance. The results show that AUTODYN-3D can realistically simulate jet formation from titanium alloy liners and that the SLM-processed liner exhibits better penetration performance than the mechanically processed liner. The existing cratering formula of jet penetration is modified to make it consistent with the aperture variations of jet penetration from titanium alloy-lined shaped charges at a short stand-off distance. The findings of this study are expected to provide technical and theoretical support for research on the penetration characteristics of the jets from titanium alloy-lined shaped charges.     

First-Principles Study on the Adsorption Behavior of O2 on the Surface of Plutonium Gallium System

To deeply understand the adsorption process of oxygen on the surface of a plutonium gallium system and to reveal the chemical reaction mechanism at the initial stage of oxidative corrosion on the surface of plutonium gallium alloy at a theoretical level, the adsorption behavior of oxygen molecules on the surface of a plutonium gallium system was investigated by a first-principles approach based on density flooding theory. The results show that the molecular bond length increases and finally breaks when the surface oxygen molecule is adsorbed on the surface of plutonium gallium system and dissociates into two atomic states. The most likely adsorption position of oxygen molecules on the surface of plutonium gallium system is hole-site vertical adsorption with the adsorption energy size of 10.7 eV. The bonding between oxygen atom and surface is mainly due to the overlapping hybridization of Pu-6s, Pu-7s, Pu-6d, Ga-3d and O-2p orbitals. Oxygen molecules mainly interact with the atoms of the first layer on the surface of the plutonium gallium system. The oxygen atoms after stable adsorption are able to diffuse to the subsurface of the plutonium gallium system after overcoming the energy barrier of 16.7 eV and form a stable structure. The research results reveal the initial reaction process and adsorption law of oxygen on the surface of plutonium gallium system from microscopic level, which is helpful to further explore the surface corrosion prevention technology of plutonium gallium system and improve the reliability and safety of plutonium gallium alloy components.     

两种种植材料对龈下优势菌粘附的影响

目的：研究不同龈下优势菌在种植材料表面的粘附特征。方法：通过将两种种植材料纯钛（ＴＡ２）及钛－６铝－４钒合金（ＴＣ４）试件分别与３种单一龈下优势菌Ｓ．ｓ、Ｆ．ｎ、Ｐ．ｇ及其混合菌共同厌氧孵育,采用菌落形成单位（ＣＦＵ）计数法量化测定培养试件表面的细菌粘附量,同时用扫描电镜观察材料表面形貌有细菌粘附情况。结果：ＴＣ４表面的各单一细菌及混合菌粘附量均少于ＴＡ２。结论：从微生态学角度而言,ＴＣ４作为种植     

不同热处理对牙科银钯铸造合金显微硬度的影响

目的 探讨不同热处理对牙科银钯铸造合金显微硬度的影响。方法 自制牙科银钯铸造合金,用牙科标准铸造程序制作合金试件。试件加热到900 ℃后冰水中淬火作软化热处理,然后分组分别进行硬化热处理、深冷处理、硬化热处理并深冷处理,以软化热处理组作为对照组。测试经不同热处理后合金的显微硬度,进行统计学分析。结果 与对照组相比,硬化热处理、深冷处理、硬化热处理并深冷处理均提高了合金的显微硬度,硬化热处理组提高了129%,深冷处理组提高了13%,硬化热处理并深冷处理组提高了141%。结论 硬化热处理和深冷处理均可以提高合金的显微硬度,而硬化热处理的提高更为明显;当硬化热处理和深冷处理联合应用时,二者对合金硬度的提高可产生累加效应。     

粗化处理对新型骨植入钛合金的生物相容性影响

目的研究国内新研制的骨植入钛合金TZS进行喷砂并酸蚀处理对成骨细胞生物学行为的影响。方法采用SD大鼠体外原代培养方法培养成骨细胞,并将细胞分别接种于新型钛合金（ 光滑表面）及表面处理的材料表面,建立体外共同培养模型。采用MTT比色法检测第3天成骨细胞的增殖率,扫描电镜（ SEM）观察细胞形态学变化,培养第5天进行细胞碱性磷酸酶功能活性检测。结果喷砂与酸蚀处理组表面的成骨细胞,在3 d时的细胞增殖率与光滑组比较有统计学差异（ P<0.05）;5 d时的处理组碱性磷酸酶活性检测值与光滑组比较无统计学差异（ P>0.05）;SEM观察成骨细胞在喷砂与酸蚀组表面具有典型形态特征,伸展良好,具有丰富的板状、丝状伪足,优于光滑组。结论喷砂并酸蚀处理的新型钛合金在体外实验表现为不同程度的促进成骨细胞增殖及功能活性表达。     

金合金、镍络合金铸造冠对磁共振成像检查的影响

目的：研究金合金与镍铬合金铸造冠对磁共振检查准确性的影响。方法：取猴右侧上颌侧切牙分别制作、配戴金合金、镍铬合金铸造冠，用2．OT Prestige MR扫描仪按临床常规进行5个常用序列(T1：自旋回波T1加权像；T2：快速自旋回波T2加权像；PD：快速自旋回波质子密度像；GRE：梯度回波T1加权像；GEEPI：单次激发平面回波成像)的头颈部扫描，观察铸造冠对图像的影响。结果：金合金冠无明显伪影形成；镍铬合金冠周围组织的影像在T1、T2、PD、GRE畸变为近似圆形的低信号伪影，在GEEPI畸变为不规则的片状信号失落；GRE影像畸变(伪影)涉及6个扫描层面，最大直径约19mm。结论：金合金修复体不影响MRI检查的准确性；镍铬合金修复体使其毗邻组织的磁共振成像发生畸变，累及范围和影响程度因扫描序列而异。     

牙用镍铬烤瓷铸造合金的Ames试验研究

目的 对镍铬烤瓷铸造合金进行鼠伤寒沙门氏菌回复突变(Ames)试验，以评价材料的潜在致突变性。方法 采用标准平板掺入法，计数TA97，TA98，TAl00，TA332在4个不同浸提浓度下，37℃培养48h后的回变菌落数。结果 该材料各浓度组的回复突变菌落数均未超过自发回变菌落数的2倍，并且无剂量反应关系。Ames试验结果为阴性。结论 牙用镍铬烤瓷铸造合金经Ames试验未见潜在致突变性。Ames试验是检测生物材料体外致突变性的一项快速，有效的方法。     

玻璃离子水门汀加入银合金粉后对其抗压强度和表面硬度的影响

目的：观察玻璃离子水门汀（ＧＩＣ）中直接加入不同比例银合金粉后的机械性能。方法：测试实验材料的抗压强度和表面硬度。结果：加入银合金粉后ＧＩＣ抗压强度和表面硬度明显下降，并且加入量越大，下降越明显。结论：ＧＩＣ中直接加入银合金粉不能改善ＧＩＣ的机械性能。     

Corrosion Behavior of Al Modified with Zn in Chloride Solution

Aluminum-based alloys have been considered candidate materials for cathodic protection anodes. However, the Al-based alloys can form a layer of alumina, which is a drawback in a sacrificial anode. The anodes must exhibit uniform corrosion to achieve better performance. Aluminum can be alloyed with Zn to improve their performance. In this sense, in the present research, the electrochemical corrosion performance of Al-xZn alloys (x = 1.5, 3.5, and 5 at.% Zn) exposed to 3.5 wt.% NaCl for 24 h was evaluated. Polarization curves, linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS) were used to identify the electrochemical behavior. The microstructure of the samples before the corrosion assessment was characterized by means of X-ray diffraction analyses (XRD) and scanning electron microscopy (SEM). In addition, microstructures of the corroded surfaces were characterized using X-ray mappings via SEM. Polarization curves indicated that Zn additions changed the pseudo-passivation behavior from what pure Al exhibited in a uniform dissolution regime. Furthermore, the addition of Zn shifted the corrosion potential to the active side and increased the corrosion rate. This behavior was consistent with the proportional decrease in polarization resistance (R_p) and charge transfer resistance (R_ct) in the EIS. The analysis of EIS was done using a mathematical model related to an adsorption electrochemical mechanism. The adsorption of chloride at the Al-Zn alloy surface formed aluminum chloride intermediates, which controlled the rate of the process. The rate constants of the reactions of a proposed chemical mechanism were evaluated.