Structure and function of 3'- untranslated region in picornavirus / 病毒学报

Both sides of the picornavirus genome have 5'-untranslated region (5'UTR) and 3'- untranslated region (3'UTR). This study demontrated that both the 5'-and 3'-UTR can form complex structures, such as stem-loop, clover and pseudoknot structure, These structures play an important role in the regulaton of the replication and translation of the viruses. This article reviewed the progress of research on the structure and function of picornavirus' 3'-UTR over recent years.

Study of Ag-containing on casting cobalt chromium alloy on the surface structure and the cell toxicity in vitro / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To detect cobalt chromium alloy antimicrobial coating silver of the surface structure and the cell toxicity in order to provide a theoretical basis for clinical application.</p><p><b>METHODS</b>Plasma spraying technique was adopted to prepare cobalt chromium alloy antimicrobial coating silver. Scanning electron microscopy, energy dispersive analysis and X-ray diffraction analysis were used to evaluate the surface properties. The methyl thiazolyl tetrazolium and flow cytometry method was adopted to test the L929 cell proliferation and the influence of the cell cycle.</p><p><b>RESULTS</b>The surface of the coating was uniform and compact, combined perfectly with substrate material. The content of the surface was mainly Ag, Cr and a small amount of Ag(2)O, Cr(2)O(3). After cobalt chromium alloy was cultured in leach liquor for 1, 2 and 3 days, the statistical result showed that there was no significant different between the three groups. The cytotoxic level of negative control group was level 0 at each time point and that of other groups was level 1 at each time point. There was no significant difference between cobalt chromium alloy and cobalt chromium alloy antimicrobial coating silver in cell toxicity (P > 0.05). There was no statistical significance of the influence on cell cycle between cobalt chromium alloy with Ag coating [the G2's rate of cell cycle was (8.23 ± 0.39)%] and cobalt chromium alloy group [the G2's rate of cell cycle was (8.70 ± 0.46)%] (P > 0.05).</p><p><b>CONCLUSIONS</b>The surface of the coating was stable and there was no significant difference between cobalt chromium alloy widely used in clinic and cobalt chromium alloy with Ag coating of the influence on proliferation of L929 cell and cell cycle, the cell compatibility of cobalt chromium with Ag coating is well.</p>

Study on the current status of spontaneous abortion of primigravid women in Jiaxing of Zhejiang province, China / 中华流行病学杂志

Objective To study the current status of spontaneous abortion of primigravid women in Jiaxing areas of Zhejiang province of China. Methods We analyzed the data from both perinatal healthcare surveillance program and spontaneous abortion, collected in Jiaxing areas by the Institute of Reproductive and Child Health, Peking University. The study population consisted of 14 769 primigravid women (excluding induced abortion, ectopic pregnancy and molar pregnancy as outcomes) attempting to become pregnant who registered between 1993 and 1995. Results 1454 spontaneous abortion cases were identified, with the spontaneous abortion rate as 9.8% (95% CI:9.3%-10.3%). The mean gestational weeks at pregnancy diagnosis were 7.6±2.1 weeks, the mean gestational weeks at miscarriage were (10.1±3.1) weeks and the incidence of first-trimester (≤12 weeks) spontaneous abortion was 7.3%(95%CI: 6.8%-7.7%), accounting for 73.7% of all the spontaneous abortion cases. A peak for risk of miscarriage was around 8-13 weeks, accounting for 37.7% of all spontaneous abortion. The observed multiple Cox regression model showed that increased spontaneous abortion rates were observed in women with age at pregnancy ≥30, being peasants and with higher education level. Conclusion The spontaneous abortion rate of primigravid women in Jiaxing areas was higher than in other areas of China. The maximum occurrence of spontaneous abortions was during period of 8-13 gestation weeks.

Effect of different heat treatment on mechanical properties and microstructure of laser welding CoCr-NiCr dissimilar alloys / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the effect of heat treatment and porcelain-fused-to-metal (PFM) processing on mechanical properties and microstructure of laser welding CoCr-NiCr dissimilar alloys.</p><p><b>METHODS</b>Samples of CoCr-NiCr dissimilar alloys with 0.5 mm thickness were laser-welded single-side under the setting parameters of 280 V, 10 ms pulse duration. After being welded, samples were randomly assigned to three groups, 10 each. Group1 and 2 received heat treatment and PFM processing, respectively. Group 3 was control group without any treatment. Tensile strength, microstructure and element distribution of samples in the three groups were tested and observed using tensile test, metallographic examinations, scanning electron microscope (SEM), and energy dispersive spectroscopy (EDS) analysis.</p><p><b>RESULTS</b>After heat treatment and PFM processing, tensile strength of the samples were (537.15 +/- 43.91) MPa and (534.58 +/- 48.47) MPa respectively, and elongation rates in Group 1 and 2 were (7.65 +/- 0.73)% and (7.40 +/- 0.45)%. Ductile structure can be found on tensile fracture surface of samples and it was more obvious in heat treatment group than in PFM group. The results of EDS analysis indicated that certain CoCr alloy diffused towards fusion zone and NiCr side after heat treatment and PFM processing. Compared with PFM processing group, the diffusion in the heat treatment group was more obvious.</p><p><b>CONCLUSIONS</b>Heat treatment and PFM processing can improve the mechanical properties and microstructure of welded CoCr-NiCr dissimilar alloy to a certain degree. The improvements are more obvious with heat treatment than with porcelain treatment.</p>