Sm掺杂BaTiO3纳米粉体的制备与表征

以钛酸四丁酯与醋酸钡为钛酸钡前驱体,PEG为分散剂,硝酸钐为掺杂物种给体,采用溶胶-凝胶法制备改性的Sm掺杂BaTiO3纳米粉体。样品经X射线衍射(XRD)与差热-热重联用(DSC-TGA)的方法对其进行了表征。研究了煅烧温度与分散剂对BaTiO3粉体粒径与相的影响。结果表明:立方相在700～850℃生成,前驱体经950℃热处理制得后呈四方相BaTiO3。分散剂PEG可抑制BaTiO3晶粒增长;随煅烧温度升高,粉体粒径增大。适量Sm掺杂可以抑制杂质BaCO3相的形成。     

Calibration of sound forces in acoustic traps

A two-dimensional or transverse acoustic trapping and its capability to noninvasively manipulate micrometersized particles with focused sound beams were experimentally demonstrated in our previous work. To apply this technique, as in optical tweezers, for studying mechanical properties of and interactions among biological particles such as cells, the trapping forces must be calibrated against known forces, i.e., viscous drag forces exerted by fluid flows. The trapping forces and the trap stiffness were measured under various conditions and the results were reported in this paper. In the current experimental arrangement, because the trapped particles were positioned against an acoustically transparent mylar membrane, the ultrasound beam intensity distribution near the membrane must be carefully considered. The total intensity field (the sum of incident and scattering intensity fields) around the droplet was thus computed by finite element analysis (FEA) with the membrane included, and it was then used in the ray acoustics model to calculate the trapping forces. The membrane effect on trapping forces was discussed by comparing effective beam widths with and without the membrane. The FEA results found that the broader beam width, caused by the scattered beams from the neighboring membrane and the droplet, resulted in the lower intensity, or smaller force, on the droplet. The experimental results showed that the measured forces were as high as 64 nN. The trap stiffness, approximated as a linear spring, was estimated by linear regressions and found to be 1.3 to 4.4 nN/μm, which was on a larger scale than that of optical trapping estimated for red blood cells, a few tenths of piconewtons/nanometer. The experimental and theoretical results were in good agreement.     

Effect of surface structure on biomechanical properties and osseointegration

The purpose of this study is to improve the bone-bonding ability between titanium implants and living bone through the control of geometric design and chemical compositions of an implant surface. We compared the tissue healing response and resulting implant stability for three surface designs by characterizing the histological and mechanical properties of the healing tissue around smooth-surfaced Ti–6Al–4V (SS), CP-Ti plasma-spray-coated (PSC), alkali- and heat-treated (AHT) implants. The implants were transversely inserted into a dog thighbone and evaluated at 4, 8, and 12 weeks. Histological examination indicated that initial matrix mineralization leading to osseointegration occurred more rapidly with the AHT implant. During the 4, 8, and 12 week healing periods, new bone on the surface of AHT implant showed denser growth than that on the SS and PSC implants. The more extensive tissue integration and more rapid matrix mineralization with the AHT implant were reflected in the mechanical test data, which demonstrated superior attachment strength and interfacial stiffness for the AHT implant after healing for 4, 8 and 12 weeks of healing because of the mechanical interlocking in the micrometer sized rough surface and the large bonding area between bone and implant caused by the nanosized porous surface structure. Histological and mechanical data demonstrate that with the appropriate surface design selection, bone bone-bonding ability can be improved and can induce acceleration of the healing response, thereby improving the potential for implant osseointegration.     

深化投资体制改革 促进水东电站建设

在深化投资体制改革中，水东水电站建设采取了４家合资的办电方式，实行了项目法人责任制。项目法人抓总体规划、抓资金到位及管理、抓施工组织、抓质量监理、抓电站经营，并通过引入市场竞争机制，有效地控制工程造价。由于建设各方的共同努力，水东电站建设取得了可喜的成绩。     

四氧化三钴/石墨复合改性阳极对海底沉积物微生物燃料电池电化学性能的影响

首次将四氧化三钴/石墨(Co_3O_4/G)复合材料用于海底沉积物微生物燃料电池(MSMFCs)阳极改性,并对阳极电化学性能和电池性能进行研究。结果表明,Co3O4/G复合改性阳极表面的微生物附着数量是空白组的6.1倍;其氧化还原电化学活性和电容特性分别是空白组的16.2倍和31.0倍;交换电流密度达到1.366×10-3m A·cm-2,电子转移动力学活性是空白组的215.6倍,且其抗极化能力最强;电荷转移电阻降至空白组的2/5,并且双电层电容和生物膜电容均得到增加;其组成电池的功率密度为735.1 m W/m2,是空白组电池的4.6倍。机理分析表明,Co_3O_4和石墨的协同作用使复合改性阳极的电容性能和电子转移速率得到提高。     

膜分离技术与变压吸附技术结合制取高浓度氧的研究

针对膜分离(MS)技术与变压吸附(PSA)技术在以空气为原料制氧方面各自存在的优缺点,尝试将二者相结合用于制取高浓度(体积分数》99.5%)氧气.通过实验证明了采用MS-PSA流程用于制取高浓度氧是行不通的.而通过PSA-MS流程可得到体积分数为99.51%的氧气.结合实验数据进行模拟计算,得出了PSA-MS制高浓度氧最佳结合点.     

Focused high frequency needle transducer for ultrasonic imaging and trapping

A miniature focused needle transducer (<1?mm) was fabricated using the press-focusing technique. The measured pulse-echo waveform showed the transducer had center frequency of 57.5 MHz with 54% bandwidth and 14?dB insertion loss. To evaluate the performance of this type of transducer, invitro ultrasonic biomicroscopy imaging on the rabbit eye was obtained. Moreover, a single beam acoustic trapping experiment was performed using this transducer. Trapping of targeted particle size smaller than the ultrasonic wavelength was observed. Potential applications of these devices include minimally invasive measurements of retinal blood flow and single beam acoustic trapping of microparticles.     

厚壁压力容器声发射源定位精度分析

刘富君等人在论文“厚壁压力容器声发射技术声源定位误差分析”中，用实验与理论相结合的方式对厚壁压力容器定位误差进行了分析，作出了误差轨迹线。文章是在此基础上对该问题作了进一步的探讨，通过等价无穷小及忽略无穷小量等数学技巧，认为误差点近似位于同一直线上，与刘富君等人的实验数据相符，并得出了该直线的解析表达式，最后根据此直线方程提出了通过实际误差点反向移动特定距离来大幅缩小厚壁带来的误差，从而大大提高定位精度。     

成矿系列研究现状及展望

成矿系列理论的形成经历了从概念的提出到理论研究及在矿产预测工作中的应用这样一个发展过程．目前的成矿系列理论还不完善，存在着诸如对概念认识不一致，成矿系列的划分原则及依据不统一，研究方法不成熟等许多问题．随着矿产勘查工作的深入开展及基础地质研究的加强，以及一些新技术、新方法的推广应用，成矿系列理论的研究和应用已展现出广阔的前景．     

Self-Healable Triboelectric Nanogenerators: Marriage between Self-Healing Polymer Chemistry and Triboelectric Devices

Based on the triboelectrification and electrostatic induction coupling, triboelectric nanogenerators (TENGs) can convert mechanical energy into electrical energy, showing a promising potential in the fields of micro/nano energy and self-powered sensors applications. However, the devices are prone to malfunction due to fatigue and damage, limiting their development and applications. In this review, according to the working modes and operational malfunctions as well as the possible solutions, it is proposed that a robust TENG device can be constructed from three perspectives: self-healing friction layers, self-healing electrodes, and self-healing whole devices. Based on the structure, suitable environment, and self-healing materials, the design ideas and fabrication approaches of self-healing TENGs in recent years are summarized in detail. Finally, the development of self-healing TENGs in energy harvesting and self-powered sensors is outlined. It is the wish to provide insights and guidance for the application design of self-healing TENGs in the future.