Fabrication and thermal conductivity of copper matrix composites reinforced by tungsten-coated carbon nanotubes

Carbon nanotubes （CNTs） were coated by tungsten using metal organic chemical vapor deposition. Magnetic stirring was employed to disperse the W-coated CNTs （W-CNTs） in a Cu matrix, and then, the mixed powders were consolidated by spark plasma sintering. The W-CNTs obtained a uniform dispersion within the Cu matrix when the W-CNT content was less than 5.0vo1%, but high content of W-CNTs （10vol%） resulted in the presence of clusters. The W-CNT/Cu composites containing low content of W-CNTs （〈5.0vol%） exhibited a higher thermal conductivity than the sintered pure Cu, while the CNT/Cu composites exhibited no increase in thermal conductivity after the incorporation of uncoated CNTs. The W-CNT content was found to play a crucial role in determining the thermal conductivity of the W-CNT/Cu composites. The thermal conductivity of the W-CNT/Cu composites increased first and then decreased with the W-CNT content increasing. When the W-CNT content was 2.5vo1%, the W-CNT/Cu composite obtained the maximum value of thermal conductivity. The thermal resistance of the （W-CNT）-Cu interface was predicted in terms of Maxwell-Gamett effective medium approximation, and its calculated value was about 3.0× 10-9 m2.K.W-l.

Friction and wear properties of PM cam materials with different boron contents

In this study,effects of B addition on the sintering densification,microstructure,hardness,friction and wear properties of sintered Fe-2.4C-4Cr-1Mo-0.5P-0.7Si-2.5Cu(in wt%)were investigated.In spite of the decreased sintered density,the addition of B changes the phase composition of the materials and their ratio.Moreover,hardness of either the matrix or the liquid solidification structure dramatically increases.These changes in micro structure result in higher friction coefficient and lower wear loss.It is observed that the addition of0.1 wt%B offers the optimum friction and wear properties with a running-in period of only 30 s and wear volume loss of 0.006 mm^(3) under the testing conditions.Such friction and wear properties are superior to those of the other two widely used cam materials,cast iron and 45 steel.

Effects of Kaixin Powder on Expression of 5-HT Receptor in Hippocampus of Depressed Rats Induced by CUMS

Objective To observe the influence of Kaixin Powder on ethology,content of 5-HT in the hippocampus, expression of m RNA, and protein in 5-HT1 A and 5-HT2 A receptors in the hippocampus of depressed rats induced by chronic unpredictable mild stress（CUMS）. Methods Twenty-four male Wistar rats were randomly divided into blank,model, Trazodone, and Kaixin Powder groups, six rats in each group. In addition to the blank control group, other groups were established the depression model induced by CUMS combined with isolated feeding. At the same time, Trazodone group and Kaixin Powder group were treated with corresponding drugs for 3 weeks. After 3 weeks of administration, the rats were sacrificed, and a series of indexes were measured such as the contents of 5-HT, m RNA expression levels of 5-HT1 A and 5-HT2 A receptors, protein expression levels of 5-HT1 A and 5-HT2 A receptors, and so on. Results A series of indexes in the model group were decreased significantly such as the body weight growth, the sugar water intake, the score of Open Field Test, the content of5-HT in the hippocampus, expression of m RNA, and protein in 5-HT1 A receptor, while the expression of m RNA and protein in 5-HT2 A receptor were increased significantly.Compared with the model group, the indexes were ameliorated in Trazodone and Kaixin Powder groups. Kaixin Powder is better than Trazodone in decreasing the level of protein in 5-HT2 A receptor. Conclusion The result indicated that the depression performance of depressed rats induced by CUMS can be ameliorated by Kaixin Powder,and the mechanism maybe concerned with increasing the contents of 5-HT, exciting 5-HT1 A receptor, and antagonising 5- HT2 A receptor.

Liposuction of the zygomatic arch area facilitates correction of temporal depression

To the Editor:Temporal depression is characterized by height difference between temporal concavity and lateral projection of the zygomatic arch.The aim of correction of temporal depression is to decrease the height difference between the concavity and lateral projection.In this study,we investigated whether decreasing the projection of the zygomatic arch by liposuction would benefit for correction of temporal depression.