公路泥石流防治结构内泥石流体运动规律研究

泥石流是一种典型的公路水毁病害,也是公路水毁时主要破坏动荷载,遵循泥石流的运动规律和道路破坏特点,建立泥石流防治技术是治理公路水毁病害的关键。文章通过分析泥石流体的运动特点,提出了合理的速流槽泥石流防治结构剖面形状,根据能量守恒原理建立的泥石流体运动方程和根据平抛理论建立的泥石流体抛程计算公式,解决了泥石流防治结构受泥石流体作用力大小的计算和泥石流防治与公路水毁病害治理效果的理论判断问题,为同类型的特大型公路泥石流防治结构设计与公路水毁病害治理提供了理论依据。     

三明治结构FeNi/Cu/FeNi多层膜巨磁阻抗效应研究

采用MEMS技术在玻璃基片上制备了三明治结构FeNi/Cu/FeNi多层膜,在1～40 MHz范围内研究了FeNi/Cu/FeNi多层膜中的巨磁阻抗效应特性.当磁场Ha施加在薄膜的长方向时,巨磁阻抗效应随磁场的增加而增加,在某一磁场下达到最大值,然后随磁场的增加而下降到负的巨磁阻抗效应.在频率为5MHz时,巨磁阻抗效应在磁场Ha=800 A/m时达到最大值26.6%.巨磁阻抗效应的最大值及负的巨磁阻抗效应与多层膜中磁各向异性轴的取向及发散有关.另外,当磁场施加在薄膜的短方向时,薄膜表现出负的巨磁阻抗效应,在频率5 MHz、磁场Ha=9600 A/m时,巨磁阻抗效应可达-15.6%.     

Fex-C1-x/Si颗粒膜的巨磁电阻效应

利用激光脉冲沉积（PLD）方法制备了沉积于硅基片上的掺杂过渡金属的非晶碳膜结构Fex-C1-x/Si。Fex-C1-x/Si的磁电阻（MR）可正可负，随温度而变化。当温度T〈258K时，Fe0．011-C0.989／Si的MR为负值；当258K〈T〈340K时，该材料的MR为正值，在室温磁场为1T时，该材料的正MR可以大于20％。且在不同的温度范围中，该材料的MR和外加磁场的依存关系呈现出不同的特点：在T=280和300K时，当磁场小于1T时，MR随磁场的增加而快速增加，之后随磁场的继续增加MR增加开始变得缓慢；在T=350K时，MR近似以磁场的B^1.5。的规律变化；而在T=30K时，MR为负值且其大小随磁场的增加而减小。利用双通道模型对该MR效应进行了初步解释。     

金属合金巨磁阻抗三明治结构多层薄膜研究进展

介绍了金属软磁合金三明治结构多层膜巨磁阻抗效应的研究和应用现状、以及多层薄膜的制备方法和表征手段。最后介绍了磁电阻磁头和磁传感器等的应用情况和对该领域研究的展望。     

离子束混合过程中Au/Fe磁性膜的巨磁电阻效应在线研究

在离子柬混合和强磁场条件下，在线研究了Au/Fe磁性膜的巨磁电阻效应，发现了不同磁场强度下的离子柬混合对巨磁电阻效应影响的规律，以及不同注入条件对样品饱和磁场的影响。讨论了样品由磁性多层膜逐渐向磁性纳米颗粒膜的转变，以及与此相关的纳米磁性颗粒在磁场作用下的非各向同性生长，并通过高分辨透射电镜(TEM)观察证实了磁性膜样品中磁性纳米Fe颗粒存在各向异性生长现象。通过对室温放置了一年以上的磁性纳米颗粒膜样品的电磁物性测量，证明利用离子柬混合技术制备的纳米颗粒膜在室温具有良好的热稳定性和时间稳定性。     

Vibration Analysis of Tb-Dy-Fe Magnetostriction Actuator and Transducer

In this paper, theoretical analysis of longitudinal free vibration was carried out for Tb-Dy-Fe series magnetostrictive actuator and transducer. The formulations considered two constitutive laws; in one we employ the standard square nonlinear constitutive equation of magnetostriction and in the other we employ the linear piezomagnetic equation. The results obtained from the nonlinear equation can be reduced to the linear piezomagnetic equation when the amplitude of the excitation magnetic field provided by the coil is very small compared to the bias magnetic field and its frequency does not induce resonance of the system. For the case of a relatively large excitation magnetic field, which usually exists for an actuator, the nonlinear constitutive equation should be adopted in order to provide an accurate prediction for the design and analysis of actuator and transducer. Another important aspect is the resonance of the Tb-Dy-Fe series transducers that was revealed in the analysis using the nonlinear constitutive equation. The resonance not only appears at the natural frequencies of the system, but also arises when the frequency of excitation current in the coil happens to be half of one of the natural frequencies of the system. This conclusion cannot be reached using the linear piezomagnetic formulation.     

Experiment on Nonlinear Properties Coupling Electromagnetism with Mechanics of Giant Rare Earth Magnetostrictive Materials

The electromagnetic and mechanical coupling properties of giant rare earth giant magnetostriction material TbxDy1 -xFe2 -z (0. 27 ≤x ≤ 0.3, 0 ≤ z ≤ 0.1 ) alloys were investigated by means of self-fabricated test apparatus. The effect of coupling mechanical with electromagnetic on magnetostrictive strain coefficient was discussed. The physical model of the coupling system was established. Based on the equivalent circuit of the coupling system, the magnetomechanical coupling coefficient was derived by means of impedance resistance analysis method.     

Comparison of isolation methods using commercially available kits for obtaining extracellular vesicles from cow milk

Extracellular vesicles (EV) are important for delivering biologically active substances to facilitate cell-to-cell communication. Milk-derived EV are widely known because of their potential for immune enhancement. However, procedures for isolating milk-derived EV have not been fully established. To obtain pure milk-derived EV and accurately reveal their function, such procedures must be established. The aim of the present study was to compare methods using commercially available kits for isolating milk-derived EV. Initially, we investigated procedures to remove casein, which is the major obstacle in determining milk-derived EV purity. We separated whey using centrifugation only, acetic acid precipitation, and EDTA precipitation. Then, we isolated milk-derived EV by ultracentrifugation, membrane affinity column, size exclusion chromatography (SEC), polymer-based isolation, or phosphatidylserine-affinity isolation. Using EV count per milligram of protein, which is a good indicator of purity, we determined that acetic acid precipitation was the best method for removing casein. Using nanoparticle tracking analysis, protein quantity analysis, and RNA quantity analysis, we comprehensively compared each isolation method for its purity and yield. We found that SEC-based qEV column (Izon Science) could collect purer milk-derived EV at higher quantities. Thus, a combination of acetic acid precipitation and qEV can effectively isolate high amounts of pure extracellular vesicles from bovine milk.     

果蔬中外泌体样纳米颗粒的分离、表征和应用研究进展

果蔬中的外泌体样纳米颗粒（exosome-like nanoparticles，ELNs）是由果蔬细胞释放的纳米级囊泡结构，与动物的外泌体具有类似的超微结构，但其脂质、蛋白质及核酸等化学成分具有显著差异，并具有独特的生物学功能。本文综述了2013年以来数十种果蔬中ELNs的相关研究进展，对其提取方法和表征手段进行了分析，重点分析了不同植物来源的ELNs中脂质、蛋白质和核酸类化学成分的组成差异，并对ELNs的潜在生理活性和载体功能进行了探讨，可为果蔬中ELNs的相关研究提供借鉴和启示。     

Biohybrid Bovine Bone Matrix for Controlled Release of Mesenchymal Stem/Stromal Cell Lyosecretome: A Device for Bone Regeneration

SmartBone^® (SB) is a biohybrid bone substitute advantageously proposed as a class III medical device for bone regeneration in reconstructive surgeries (oral, maxillofacial, orthopedic, and oncology). In the present study, a new strategy to improve SB osteoinductivity was developed. SB scaffolds were loaded with lyosecretome, a freeze-dried formulation of mesenchymal stem cell (MSC)-secretome, containing proteins and extracellular vesicles (EVs). Lyosecretome-loaded SB scaffolds (SBlyo) were prepared using an absorption method. A burst release of proteins and EVs (38% and 50% after 30 min, respectively) was observed, and then proteins were released more slowly with respect to EVs, most likely because they more strongly adsorbed onto the SB surface. In vitro tests were conducted using adipose tissue-derived stromal vascular fraction (SVF) plated on SB or SBlyo. After 14 days, significant cell proliferation improvement was observed on SBlyo with respect to SB, where cells filled the cavities between the native trabeculae. On SB, on the other hand, the process was still present, but tissue formation was less organized at 60 days. On both scaffolds, cells differentiated into osteoblasts and were able to mineralize after 60 days. Nonetheless, SBlyo showed a higher expression of osteoblast markers and a higher quantity of newly formed trabeculae than SB alone. The quantification analysis of the newly formed mineralized tissue and the immunohistochemical studies demonstrated that SBlyo induces bone formation more effectively. This osteoinductive effect is likely due to the osteogenic factors present in the lyosecretome, such as fibronectin, alpha-2-macroglobulin, apolipoprotein A, and TGF-β.