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%.     

Malignant Transformation of Giant Cell Tumour of Bone: A Review of Literature and the Experience of a Referral Centre

Giant cell tumour of bone (GCTB) is a benign, locally aggressive primary bone neoplasm that represents 5% of all bone tumours. The principal treatment approach is surgery. Although generally GCTB is considered only a locally aggressive disease, it can metastasise, and lung metastases occur in 1–9% of patients. To date, only the use of denosumab has been approved as medical treatment for GCTB. Even more rarely, GCTB undergoes sarcomatous transformation into a malignant tumour (4% of all GCTB), but history of this malignant transformation is unclear and unpredictable. Considering the rarity of the event, the data in the literature are few. In this review, we summarise published data of GCTB malignant transformation and we analyse three cases of malignant transformation of GCTB, evaluating histopathology, genetics, and radiological aspects. Despite the rarity of this event, we conclude that a strict follow up is recommended to detect early malignant transformation.     

Effects of static axial strain on the tensile properties and failure mechanisms of self-assembled collagen fibers

Collagen fibers form the structural units of connective tissue throughout the body, transmitting force, maintaining shape, and providing a scaffold for cells. Our laboratory has studied collagen self-assembly since the 1970s. In this study, collagen fibers were self-assembled from molecular collagen solutions and then stretched to enhance alignment. Fibers were tested in uniaxial tension to study the mechanical properties and failure mechanisms. Results reported suggest that axial orientation of collagen fibrils can be achieved by stretching uncrosslinked collagen fibers. Stretching by about 30% not only results in decreased diameter and increased tensile strength but also leads to unusual failure mechanisms that inhibit crack propagation across the fiber. It is proposed that stretching serves to generate oriented fibrillar substructure in self-assembled collagen fibers. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1429–1440, 1997     

Sex pheromone components of the giant looper,Boarmia selenaria schiff. (Lepidoptera: Geometridae): Identification,synthesis, electrophysiological evaluation,and behavioral activity

(Z,Z)-6,9-cis-(3S,4R)-Epoxynonadecadiene9a and (Z,Z,Z)-3,6,9-nonadecatriene have been identified as sex pheromone components in female ovipositor extracts and effluvia of the geometridBoarmia selenaria. The identification was based on relative retention times on gas chromatographic columns, GC-MS, chemical enantioselective syntheses, EAG, wind-tunnel behavioral experiments, and field tests. A single female ovipositor extract contained an average of 42 ng of (Z,Z)-6,9-cis-3,4-epoxynonadecadiene and 2 ng of (Z,Z,Z)-3,6,9-nonadecatriene.EAG, wind-tunnel behavioral studies, and field tests demonstrated that maleB. selenaria exhibit preferential attraction for the (3S,4R)-enantiomer of (Z,Z)-6,9-cis-3,4-epoxynonadecadiene. Only in effluvia and ovipositor extracts of calling females was (Z,Z)-6,9-cis- 3,4-epoxynonadecadiene detected, whereas relatively high amounts of (Z,Z,Z)-3,6,9-nonadecatriene were found in noncalling females. Wind-tunnel behavioral studies showed that (Z,Z,Z)-3,6,9-nonadecatriene did not elicit any response in the males, and when tested in combination with a mixture of monoepoxynonadecadienes, (Z,Z,Z)-3,6,9-nonadecatriene decreased the observed behavioral responses. A possible precursor role for (Z,Z,Z)-3,6,9-nonadecatriene in the pheromonal system is discussed.     

Surfactant-Assisted Purification of Hydrophobic DNA Nanostructures

Purification of functional DNA nanostructures is an essential step in achieving intended functions because misfolded structures and the remaining free DNA strands in a solution can interact and affect their behavior. However, due to hydrophobicity-mediated aggregation, it is difficult to purify DNA nanostructures modified with hydrophobic molecules by conventional methods. Herein, we report the purification of cholesterol-modified DNA nanostructures by using a novel surfactant-assisted gel extraction. The addition of sodium cholate (SC) to the sample solution before structure folding prevented aggregation; this was confirmed by gel electrophoresis. We also found that adding sodium dodecyl sulfate (SDS) to the sample inhibited structural folding. The cholesterol-modified DNA nanostructures prepared with SC were successfully purified by gel extraction, and their ability to bind to the lipid membrane surfaces was maintained. This method will facilitate the purification of DNA nanostructures modified with hydrophobic molecules and expand their applicability in the construction of artificial cell-like systems.     

Giant dielectric response and grain heterogeneity of Y2/3Cu3Ti4O12–TiO2 composite ceramics fabricated by hydrothermal process

Due to the boom of the electronic information industry, dielectric ceramic materials are widely applied in passive components such as multilayer ceramic capacitors. In this article, Y_2/3Cu₃Ti₄O₁₂–TiO₂ composite ceramics with outstanding dielectric properties (ε_r = 2.29 × 10⁶ at 20 Hz, ε_r = 4.49×10⁵ at 1 kHz) were successfully prepared by hydrothermal and in situ solid-state methods. The minimum dielectric loss value (at 1 kHz) of the obtained composite ceramics is about 0.57. The experimental results show that Y_2/3Cu₃Ti₄O₁₂ has a composite perovskite structure with cation vacancies, which causes internal electron-pinned defect-dipole, and the easy entry of excessive titanium ions to produce donor defects. Meanwhile, the heterogeneous grains with a pomegranate-like microstructure were observed in the prepared composite ceramics, and interfacial polarization between subgrain boundaries was substantiated by impedance analysis. The abundant weakly trapped electrons and more polarized interfaces formed by grain and subgrain boundaries are the primary sources of the excellent dielectric properties of composite ceramics.     

Thermal Stability Threshold for Amyloid Formation in Light Chain Amyloidosis

Light chain (AL) amyloidosis is a devastating disease characterized by amyloid deposits formed by immunoglobulin light chains. Current available treatments involve conventional chemotherapy and autologous stem cell transplant. We have recently concluded a phase III trial comparing these two treatments. AL amyloidosis patients who achieve hematological complete response (CR) do not necessarily achieve organ response regardless of the treatment they received. In order to investigate the possible correlation between amyloid formation kinetics and organ response, we selected AL amyloidosis patients from the trial with kidney involvement and CR after treatment. Six patients were selected and their monoclonal immunoglobulin light chains were characterized. The proteins showed differences in their stability and their kinetics of amyloid formation. A correlation was detected at pH 7.4, showing that less stable proteins are more likely to form amyloid fibrils. AL-T03 is too unstable to form amyloid fibrils at pH 7.4. This protein was found in the only patient in the study that had organ response, suggesting that partially folded species are required for amyloid formation to occur in AL amyloidosis.     

隧道结巨磁电阻材料的研究进展

在概述隧道结巨磁电阻效应及其机理的基础上,综合介绍了多层薄膜结构、微颗粒膜结构和近年来出现的基于多晶隧道结结构的巨磁电阻效应及其相关材料的研究最新进展。重点讨论了涉及隧道结磁电阻材料类型、化学组成、结构与性能、制备技术以及潜在的应用前景,对制备工艺简单、成本低并可能带来突破性发展的多晶隧道结巨磁电阻材料作了展望。     

Study on Tribological Properties of Polytetrafluoroethylene Drawn Uniaxially at Different Temperature

Summary: Wear behavior correlations with morphology have been established from polytetrafluoroethylene (PTFE) drawn at 200, 327, and 375 °C with draw ratio about 4. The friction coefficient and wear rate for PTFE drawn at 327 °C are lower and the wear rate is lower than that of undrawn PTFE by about 30%. The structures of samples were characterized by scanning electron microscope (SEM), DSC, and wide angle X‐ray diffraction (WAXD). Results indicate that the debris morphologies of samples are different. The differences in the tribological behavior of undrawn and drawn samples were attributed to the improvement of the degree of the crystalline, fibrillation, and orderliness by drawing, especially, for PTFE drawn at 327 °C. The orderliness of molecular arrangement along the drawn direction is also higher for PTFE drawn at 327 °C than those of PTFE drawn at 200 and 375 °C, respectively. Therefore, the intensity of covalent bond along drawn direction is higher. The shear resistance and the deformability of the material are greatly improved and the size of the wear breakage unit decreases, which results in a good tribological property for PTFE drawn at 327 °C.

SEM morphology of fractured surface perpendicular to the draw direction for PTFE drawn at 327 °C.     

Self-Assembling Properties and Recovery Effects on Damaged Skin Cells of Chemically Synthesized Mannosylerythritol Lipids

Mannosylerythritol lipids (MELs), which are one of the representative sugar-based biosurfactants (BSs) produced by microorganisms, have attracted much attention in various fields in the sustainable development goals (SDGs) era. However, they are inseparable mixtures with respect to the chain length of the fatty acids. In this study, self-assembling properties and structure-activity relationship (SAR) studies of recovery effects on damaged skin cells using chemically synthesized MELs were investigated. It was revealed, for the first time, that synthetic and homogeneous MELs exhibited significant self-assembling properties to form droplets or giant vesicles. In addition, a small difference in the length of the fatty acid chains of the MELs significantly affected their recovery effects on the damaged skin cells. MELs with medium or longer length alkyl chains exhibited much higher recovery effects than that of C18-ceramide NP.