Electrical Transport and Thermoelectric Properties of SnSe-SnTe Solid Solution

SnSe is considered as a promising thermoelectric (TE) material since the discovery of the record figure of merit (ZT) of 2.6 at 926 K in single crystal SnSe. It is, however, difficult to use single crystal SnSe for practical applications due to the poor mechanical properties and the difficulty and cost of fabricating a single crystal. It is highly desirable to improve the properties of polycrystalline SnSe whose TE properties are still not near to that of single crystal SnSe. In this study, in order to control the TE properties of polycrystalline SnSe, polycrystalline SnSe–SnTe solid solutions were fabricated, and the effect of the solid solution on the electrical transport and TE properties was investigated. The SnSe_1−xTe_x samples were fabricated using mechanical alloying and spark plasma sintering. X-ray diffraction (XRD) analyses revealed that the solubility limit of Te in SnSe_1−xTe_x is somewhere between x = 0.3 and 0.5. With increasing Te content, the electrical conductivity was increased due to the increase of carrier concentration, while the lattice thermal conductivity was suppressed by the increased amount of phonon scattering. The change of carrier concentration and electrical conductivity is explained using the measured band gap energy and the calculated band structure. The change of thermal conductivity is explained using the change of lattice thermal conductivity from the increased amount of phonon scattering at the point defect sites. A ZT of ~0.78 was obtained at 823 K from SnSe_0.7Te_0.3, which is an ~11% improvement compared to that of SnSe.

[An in vitro of acrylonitrile inducing early damage on buccal mucosa of murine]

ObJECTIVE:Understand the change and damage of rats and mice buccal mucosa tissue structure posioned by acrylonitrile and alcohol. METHODS: Using optical microscope and transmitted electron microscope (TEM) techniques, observed the structure of rats and mice buccal mucosa which posioned by acrylonitrile and alcohol for 13 weeks in different dosages. RESULTS: Acrylonitrile can damage the ultrastructure of the cells and lead to precancerous dysplasia,such as enlargement and deformation of nuclei, reducing of desmosomes and hemidesmosomes,break of basement membrane,swelling and denaturalization of mitochondrion. The degree of damage was correlated with its dosage. Alcohol can increase the damage caused by acrylonitrile. CONCLUSION: Both acrylonitrile and alcohol can destroy the ultrastructure of cells,TEM is helpful for diagnosing disease in their early stage,and buccal mucosa can be used as a window for observing the disease caused by many toxic factors.

[Clinical and experimental studies on the treatment of severe facioplegia with compressing drug, acupuncture and infrared rays]

In 160 patients with severe facioplegia detected by the strength-duration curve, partial or complete reaction of degeneration of the facial nerve and its related muscles occurred in 158 patients and no reaction of degeneration in 2 patients. All the patients were arbitrarily divided into 2 groups. One group of 62 patients was treated with the regimen 1: Mianmasan adding acupuncture and the other of 98 patients with the regimen 2: modified Mianmasan adding acupuncture and red lighting. The treatment concretely was an application method by dusting the Mianmasan, over the scarified skin corresponding to the selected acupoints and motor points, and finally stick a piece of adhesive plaster on them. The clinical experiment was carried out by using double contrast method, i.e., autogenous and allogenic contrasts with ear pulse wave and skin temperature records. It was confirmed that the affected side of the face had chronic tissue ischemia and returned to normal after treatment. The results showed that among 160 treated patients, 70(43.8%) were cured, 46 (28.7%) markedly improved, 43 (26.9%) improved and 1 (0.6%) remained ineffective. By the statistical analysis, it was demonstrated that the curative effect of regimen 2 was superior to that of regimen 1 (P less than 0.01), and the effective rate in the patients with partial reaction of degeneration was higher than that in those with complete reactcon of degeneration (P less than 0.05).