Anisotropic Galvanomagnetic Effects in Single Cubic Crystals: A Theory and Its Verification.

A theory of anisotropic galvanomagnetic effects in single cubic crystals and its experimental verifications are presented for the current in the (001) plane. In contrast to the general belief that galvanomagnetic effects in single crystals are highly sensitive to many internal and external effects and have no universal features, the theory predicts universal angular dependencies of longitudinal and transverse resistivity and various characteristics when magnetization rotates in the (001) plane, the plane perpendicular to the current, and the plane containing the current and [001] direction. The universal angular dependencies are verified by experiments on Fe_{30}Co_{70} single cubic crystal film. The findings provide new avenues for fundamental research and applications of galvanomagnetic effects, because single crystals offer advantages over polycrystalline materials for band structure and crystallographic orientation engineering.

Magnetostrictive current sensor with high sensitivity and a large linear range for the subway.

Stray current affects the safe operation of subway equipment. The stray current leakage point can be located by measuring the current of subway running track. A magnetostrictive current sensor with high sensitivity and a large linear range is proposed to monitor track current. The design of the sensor is qualitatively guided by a set of finite element method (FEM) simulations to improve the sensitivity of the sensor. However, when the sensitivity of the sensor increases, the linear range decreases. To solve this problem, a novel current sensor, to the best of our knowledge, which is composed of magnetostrictive composites, steel bars, and adjustable coils, is presented. The linear range of the sensor is expanded by adjusting the different DC bias magnetic fields generated by the adjustable coils. The results show that when the measured current is 0-500 A and 500-1000 A, the Terfenol-D (TD) mass is only 0.14 g, and the sensitivity of the sensor is 0.391 µÉ›/A and 0.418 µÉ›/A, respectively. The current measurement with low cost, high sensitivity, and larger linear working range is realized, which is suitable for monitoring stray current leakage points.

Pancreatic stem cells differentiate into insulin-secreting cells on fibroblast-modified PLGA membranes.

Diabetes mellitus is an epidemic worldwide. Pancreatic stem cells can be induced to differentiate into insulin-secreting cells, this method is an effective way to solve the shortage of islet donor. Poly (lactic acid-co-glycolic acid (PLGA) copolymer is an excellent scaffold for tissue engineering as it presents good biocompatibility and film forming properties. In this study, we adopted biological methods, using fibroblast-coated PLGA diaphragm to form a biological membrane, and then pancreatic stem cells were cultured on the fibroblast-modified PLGA membrane and the two-step induction method was utilized to induce the differentiation of pancreatic stem cells into insulin-secreting cells. The proliferation and differentiation of pancreatic stem cells on the fibroblast-modified PLGA membrane as well as the expression of genes related to the differentiation of pancreatic stem cells were examined in both normal and induced cultures to explore the potential of fibroblast-modified PLGA membrane for the transplantation to treat diabetes mellitus. The results indicated that fibroblasts can effectively improve the cell compatibility and histocompatibility of the PLGA membrane and promote the proliferation and differentiation of pancreatic stem cells. After induction, real-time fluorescence quantitative PCR (FQRT-PCR) results showed there were more Notch receptors and its ligands expressed in the membranes of pancreatic stem cells than non-induced pancreatic stem cells or fibroblast. Semiconductor quantum dot coupled-anti-complex probe experiments revealed that induced pancreatic stem cells had higher expression levels of Notch 2 and Delta-like 1 than non-induced ones, which may regulate the expression of Neurogenin-3 (Ngn3) and Hairy/Enhancer of split-1 gene (Hes1) through Notch signaling interaction between fibroblasts and pancreatic stem cells as well as enhance the proliferation of pancreatic stem cells and their differentiation into insulin-secreting cells. Further, our study suggests that the fibroblast-modified PLGA membrane can be used as matrix material composed of pancreatic stem cells or other stem cells to construct artificial islet tissue for the treatment of diabetes mellitus.

Construction of functional pancreatic artificial islet tissue composed of fibroblast-modified polylactic- co-glycolic acid membrane and pancreatic stem cells.

Objective To improve the biocompatibility between polylactic- co-glycolic acid membrane and pancreatic stem cells, rat fibroblasts were used to modify the polylactic- co-glycolic acid membrane. Meanwhile, we constructed artificial islet tissue by compound culturing the pancreatic stem cells and the fibroblast-modified polylactic- co-glycolic acid membrane and explored the function of artificial islets in diabetic nude mice. Methods Pancreatic stem cells were cultured on the fibroblast-modified polylactic- co-glycolic acid membrane in dulbecco's modified eagle medium containing activin-A, ß-catenin, and exendin-4. The differentiated pancreatic stem cells combined with modified polylactic- co-glycolic acid membrane were implanted subcutaneously in diabetic nude mice. The function of artificial islet tissue was explored by detecting blood levels of glucose and insulin in diabetic nude mice. Moreover, the proliferation and differentiation of pancreatic stem cells on modified polylactic- co-glycolic acid membrane as well as the changes on the tissue structure of artificial islets were investigated by immunofluorescence and haematoxylin and eosin staining. Results The pancreatic stem cells differentiated into islet-like cells and secreted insulin when cultured on fibroblast-modified polylactic- co-glycolic acid membrane. Furthermore, when the artificial islet tissues were implanted into diabetic nude mice, the pancreatic stem cells combined with polylactic- co-glycolic acid membrane modified by fibroblasts proliferated, differentiated, and secreted insulin to reduce blood glucose levels in diabetic nude mice. Conclusion Pancreatic stem cells can be induced to differentiate into islet-like cells in vitro. In vivo, the artificial islet tissue can effectively regulate the blood glucose level in nude mice within a short period. However, as time increased, the structure of the artificial islets was destroyed due to the erosion of blood cells that resulted in the gradual loss of artificial islet function.