Controllable fabrication of self-organized nano-multilayers in copper–carbon films

In order to clarify the influence of methane concentration and deposition time on self-organized nano-multilayers,three serial copper-carbon films have been prepared at various methane concentrations with different deposition times using a facile magnetron sputtering deposition system. The ratios of methane concentration(CH4/Ar+CH4) used in the experiments are 20%, 40%, and 60%, and the deposition times are 5 minutes, 20 minutes, and 40 minutes, respectively.Despite the difference in the growth conditions, self-organizing multilayered copper-carbon films are prepared at different deposition times by changing methane concentration. The film composition and microstructure are investigated by x-ray photoelectron spectroscopy(XPS), x-ray diffraction(XRD), field emission scanning electron microscopy(FESEM), and high-resolution transmission electron microscopy(HRTEM). By comparing the composition and microstructure of three serial films, the optimal growth conditions and compositions for self-organizing nano-multilayers in copper-carbon film are acquired. The results demonstrate that the self-organized nano-multilayered structure prefers to form in two conditions during the deposition process. One is that the methane should be curbed at low concentration for long deposition time,and the other condition is that the methane should be controlled at high concentration for short deposition time. In particular, nano-multilayered structure is self-organized in the copper-carbon film with copper concentration of 10-25 at.%.Furthermore, an interesting microstructure transition phenomenon is observed in copper-carbon films, that is, the nanomultilayered structure is gradually replaced by a nano-composite structure with deposition time and finally covered by amorphous carbon.

A Non-invasive Method of Fetal Growth Evaluation

The fetal weight vs. the gestational age has great significance for fetal growth evaluation in clinic especially in the judgement of IUGR. In this paper, the quantification theory and its application for estimation of the gestational age and fetal weight are reported.It is the first time that the theory is applied in this field. The estimation error.of gestational age is less than one week and that of fetal weight is less than 130g.

酸敏感高分子纳米药物载体在肿瘤治疗中的应用研究

纳米递药系统有望实现药物靶向递送增加其生物利用度、降低其毒副作用,在肿瘤治疗方面受到了广泛关注.但是,抗肿瘤药物的体内递送是一个多步骤的复杂过程,如何有效克服肿瘤组织(肿瘤部位的特异性富集滞留、深部渗透、高效细胞摄取)及细胞内(胞内可控药物释放)的多重物理屏障是抗肿瘤纳米递药系统面临的重大挑战.利用肿瘤组织及细胞内的微酸环境,在药物载体材料中引入酸响应化学键或功能基团,构建酸响应性纳米递药系统是实现肿瘤特异性药物递送、提高药物递送效率的有效途径.本文系统回顾了本课题组近年来在运用酸敏感高分子载体材料设计构建智能纳米递药系统,克服药物递送的关键物理屏障,改善肿瘤治疗效果方面的研究进展,并对其转化前景进行了展望.

Effects of keto acid supplements on Chinese patients receiving maintenance hemodialysis:a prospective,randomized,controlled,single-center clinical study

Background:The effects of keto acid(KA)supplements on Chinese patients receiving maintenance hemodialysis(MHD)are unclear.This study aimed to evaluate the effects of KA supplementation on nutritional status,inflammatory markers,and bioelectric impedance analysis(BIA)parameters in a cohort of Chinese patients with MHD without malnutrition.Methods:This was a prospective,randomized,controlled,single-center clinical study conducted in 2011 till 2014.Twenty-nine patients with MHD were randomly assigned to a control(n=14)or a KA(n=15)group.The control group maintained a dietary protein intake of 0.9 g/kg/day.The KA group received additional KA supplement(0.1 g/kg/day).BIA was used to determine the lean tissue mass,adipose tissue mass,and body cell mass.The patients,nutritional status,dialysis adequacy,and biochemical parameters were assessed at the ends of the third and sixth months with t test or Wilcoxon rank-sum test.Results:The daily total energy intake for both groups was about 28 kcal/kg/day.After 6 months,the Kt/V(where K is the dialyzer clearance of urea,t is the dialysis time,and V is the volume of the distribution of urea)was 1.33±0.25 in KA group,and 1.34±0.25 in the control group.The median triceps skin-fold thickness in KA group was 12.00 and 9.00 mm in the control group.In addition,the median hand-grip strength in KA group was 21.10 and 25.65 kg in the control group.There were no significant differences between the groups with respect to the anthropometry parameters,dialysis adequacy,serum calcium and phosphorus levels,inflammatory markers,and amino-acid profiles,or in relation to the parameters determined by BIA.Both groups achieved dialysis adequacy and maintained nutritional status during the study.Conclusions:In this cohort of Chinese patients with MHD,the patients in the control group whose dietary protein intake was 0.9 g/kg/day and total energy intake was 28 kcal/kg/day,maintained well nutritional status during study period.The KA supplement(0.1 g/kg/day)did not improve the essential amino acid/non-essential amino acid ratio,nor did it change the patients5 mineral metabolism,inflammatory parameters,or body compositions.

Phase precipitation behavior and tensile property of a Ti-Al-Sn-Zr-Mo-Nb-W-Si titanium alloy

The characteristic of precipitation behavior of a2 phase and silicide, and the tensile properties at room temperature and 650℃after heat treatments in anovel TiAl-Sn-Zr-Mo-Nb-W-Si titanium alloy（BTi-6431 S） were investigated by microstructure analysis and mechanics performance testing. The results show that no second phase precipitates after solution treatment(980 ℃/2 h, air cooling（AC）). However, when the solution-treated specimens are aged at 600 ℃（600 ℃/2 h,AC）,α;phase precipitates in the primary α phase, and the size of α;phase increases with the aging temperature increasing to 750 ℃. Meanwhile, 50-100-nm S2-type silicide particles precipitate along lamellar phase boundaries of transformed β phase after aging at 750 ℃. BTi-6431 S alloy shows the best650 ℃ ultimate tensile strength（UTS） and yield strength（YS） when treated in solution treatment. However, aging treatment results in a decline in 650 ℃ ultimate tensile strength. This may be attributed to the loss of solution strengthening due to the depletion of Al, Si and Zr of the matrix caused by the precipitation of Ti;Al and（TiZr）;Si;.Silicide is a brittle phase; therefore, its precipitation causes a sharp decrease in the room-temperature ductility of BTi-6431 S alloy.