Comparative in vitro Cytotoxicity Toward Human Osteoprogenitor Cells of Polycaprolactones Synthesized from Various Metallic Initiators

Various poly(ε‐caprolactone)s (PCLs) prepared by ring‐opening polymerization of ε‐caprolactone (CL) initiated by a range of metallic derivatives such as alkoxides, Al(OiPr)₃, La(OiPr)₃, Sn(octanoate)₂, Ti(OiPr)₄, Zn[O(CH₂)₃NH^tBoc]₂, or borohydride La(BH₄)₃(THF)₃ were evaluated for their in vitro cytotoxicity. The amount of residual metal present in the polymer samples was measured and compared to the initial quantity introduced. The effect of the metallic system on the biocompatibility profiles of the resulting polyesters was evaluated in vitro on PCL films from a series of cytotoxicity tests involving MTT and neutral red assays upon exposure to human osteoprogenitor cells. The absence of toxic influence of all these PCLs suggests that they may be used as biomaterials in contact with living human cells.

     

The creation of the magnetic and metallic characteristics in low-width MoS2 nanoribbon (1D MoS2): A DFT study

A basic understanding of the catalytic performance is needed to probe the physical properties that change with a reduction in the catalytic clusters size. It has been shown that the edge of low-width MoS₂ nanoribbon has a metallic characteristic, while that of bulk MoS₂ has a semi-conductive characteristic. For probing the observations, we constructed the models representing the surface atoms and the edge atoms of the MoS₂ nanoribbon. The nanoribbon-like model can also be used to model the edge atoms of the nanocluster MoS₂ .Then we calculated the density of states (DOS) of infinitely two-dimensional MoS₂ and of the structure corresponding to the edge atoms of the MoS₂ nanoribbon-like structure with Wien2K software. The magnetic moment of structures was calculated for identifying the magnetic structure. We found that the bulk MoS₂ and infinitely two-dimensional MoS₂ are semi-conductive and not magnetic, while the computation model corresponding to MoS₂ nanoribbon is metallic. The calculation anticipates that the edges of the MoS₂ nanocluster and the low-width MoS₂ nanoribbon are strongly magnetic.     

On the quality of plate reverberation

Metallic plates are used in recording studios to create artificial reverberation. In this paper, the flexural vibrations of such plates are analysed in order to better understand the influence of geometry and materials on the quality of plate reverberation. A comparison is made with acoustic reverberation, both in the time and frequency domain. This comparison is supported by objective criteria such as modal density and density of reflections. From a physical point of view, the internal and external damping mechanisms are examined in detail since they determine the frequency dependence of the reverberation time. Theoretical results are validated through comparison with experiments performed on an EMT140 reverberation plate. The underlying model is aimed at developing numerical simulations of plates (virtual reverberators) allowing a large variety of reverberations based on variations of geometry and materials as input parameters.     

金属卟啉化合物激发态折射与激发态吸收增强瞬态热折射竞争研究

应用激发态吸收增强瞬态热折射理论结合激发态折射理论研究了新型锌卟啉化合物Zn-porphyrin 中激发态吸收增强瞬态热折射与激发态折射间的相互竞争. 样品在不同脉宽激光激发下呈现自聚焦-自散焦间的转化. 当入射激光脉宽为4 ns时,激发态折射占主要地位,样品呈现自聚焦性质;当入射激光脉宽为8ns时,激发态吸收增强瞬态热折射占主要地位,激发态折射占次要地位,样品呈现自散焦性质. 关键词： 金属卟啉化合物 激发态折射 瞬态热折射     

Stoichiometry analysis of titanium oxide coating by LIBS

In this work, laser induced breakdown spectroscopy (LIBS) is used to determine the composition of titanium oxide film produced by anodized of Ti6Al4V alloy. We have used Ti lines in the spectral region between 470–520 nm to determine temperature of the plasma generated on anodized surface of Ti6Al4V alloy for temperature determination by Boltzmann plot method. In order to measure the content of oxygen and titanium ratio on the surface the alloy, we have used the oxygen lines 777.194, 777.417 and 777.539 nm, and titanium lines 780.597 and 782.491 nm observed in an ambient of argon. Finally, we report the possibilities for the determination of the coating chemical composition using LIBS.     

开孔金属腔屏蔽效能快速算法适用性评估

对开孔金属腔屏蔽效能（SE）的四种快速算法传输线等效电路法、EMT法、ILCM法、Modal-MOM法的适用性进行评估,为不同实际工程问题选用恰当的算法提供了依据。为了解决传统SE结果描述方法不适用于快速算法适用性评估的问题,采用绝对误差和曲线相关系数这两个参数,提出SE随金属腔和孔缝尺寸单独变化的Contour图描述方法。在此基础上,利用864组不同形状、尺寸矩形金属腔的SE计算结果,分析并确定了四种SE快速算法满足不同计算精度时适用的腔体模式数。结果表明,在同等计算精度条件下,Modal-MOM算法可适用的腔体模式数最多,ILCM算法次之,而传输线等效电路法适用腔体模式数最少,这些结果为实际工程应用提供了指导。     

用于第一镜表面的金属玻璃薄膜研究

为解决大口径非晶金属第一镜实现难题,在研究块体金属玻璃Co61.2B26.2Si7.8Ta4.8材料基础上,采用金属玻璃块体材料制作拼接成溅射靶材,通过非平衡磁控溅射镀膜方法,实现了Co61.2B26.2Si7.8Ta4.8非晶金属薄膜第一镜。研究结果表明：通过成分设计及合成靶材的设计,能够实现与块体金属玻璃具有相同光学特性的非晶薄膜第一镜;通过Cr成分改进,能够进一步提高非晶金属薄膜第一镜在可见光波段的光谱反射率。     

影响金属玻璃中剪切带行为的微观机制

论文对金属玻璃发生剪切失稳形成剪切带的行为进行了分析,得到了其发生剪切失稳时的临界自由体积浓度,预测结果与实验观察和模拟结果吻合;利用两种方法对其剪切带厚度进行了预测,结果表明基于剪切失稳临界波长预测金属玻璃剪切带厚度的方法只在发生剪切失稳后极短的时间内有效,对成熟剪切带厚度的预测必须考虑自由体积的扩散效应;考察了金属玻璃的宏微观材料参数对其剪切带厚度的影响及其微观机制,发现金属玻璃剪切带厚度对其宏观材料参数(泊松比)不敏感,对与剪切相变区相关的微结构参数敏感.     

非均匀泡沫金属材料在冲击载荷下的变形模拟

提出一种二维非线性弹塑性质量-弹簧-连杆模型,该模型将泡沫金属材料离散成许多质量块,质量块在受载方向由非线性弹塑性弹簧连接,垂直于受载方向由可延伸的弹性连杆铰接。采用该模型模拟并分析了层非均匀泡沫金属材料及局部不均匀泡沫金属材料在冲击载荷下的变形特性,说明了非均匀性对泡沫金属材料冲击变形的影响。     

用于交叉碰撞实验的金属毛细管式中性原子源

基于金属材料的加热蒸发机制,在钽舟的基础上设计了一套结构简易的中性原子源。该原子源的源仓和加热体均采用金属毛细管形式,保证了原子源具有耗能小、加热温度高的特点;提供的中性原子流具有发散度小、密度大、稳定性好的优点。采用加热蒸发铥样品的方法对其性能做了详细的检验,结果它在低耗能的情况下,温度能够顺利升高到2 600 K;可以连续8 h提供强度为8.5×1016/s的中性Tm原子流,且束流的稳定性好于±5％。充分证实了该套原子源应用于电子、离子和光子与中性原子流交叉碰撞实验的可靠性。