Prevalence and trend of hepatitis C virus infection among blood donors in Chinese mainland: a systematic review and meta-analysis

<p>Abstract</p> <p>Background</p> <p>Blood transfusion is one of the most common transmission pathways of hepatitis C virus (HCV). This paper aims to provide a comprehensive and reliable tabulation of available data on the epidemiological characteristics and risk factors for HCV infection among blood donors in Chinese mainland, so as to help make prevention strategies and guide further research.</p> <p>Methods</p> <p>A systematic review was constructed based on the computerized literature database. Infection rates and 95% confidence intervals (95% CI) were calculated using the approximate normal distribution model. Odds ratios and 95% CI were calculated by fixed or random effects models. Data manipulation and statistical analyses were performed using STATA 10.0 and ArcGIS 9.3 was used for map construction.</p> <p>Results</p> <p>Two hundred and sixty-five studies met our inclusion criteria. The pooled prevalence of HCV infection among blood donors in Chinese mainland was 8.68% (95% CI: 8.01%-9.39%), and the epidemic was severer in North and Central China, especially in Henan and Hebei. While a significant lower rate was found in Yunnan. Notably, before 1998 the pooled prevalence of HCV infection was 12.87% (95%CI: 11.25%-14.56%) among blood donors, but decreased to 1.71% (95%CI: 1.43%-1.99%) after 1998. No significant difference was found in HCV infection rates between male and female blood donors, or among different blood type donors. The prevalence of HCV infection was found to increase with age. During 1994-1995, the prevalence rate reached the highest with a percentage of 15.78% (95%CI: 12.21%-19.75%), and showed a decreasing trend in the following years. A significant difference was found among groups with different blood donation types, Plasma donors had a relatively higher prevalence than whole blood donors of HCV infection (33.95% <it>vs </it>7.9%).</p> <p>Conclusions</p> <p>The prevalence of HCV infection has rapidly decreased since 1998 and kept a low level in recent years, but some provinces showed relatively higher prevalence than the general population. It is urgent to make efficient measures to prevent HCV secondary transmission and control chronic progress, and the key to reduce the HCV incidence among blood donors is to encourage true voluntary blood donors, strictly implement blood donation law, and avoid cross-infection.</p

Numerical and experimental studies on the\ud fracture behavior of rubber-toughened epoxy\ud in bulk specimen and laminated composites

To study the toughening mechanisms of liquid rubber (LR) and core-shell rubber (CSR) in\ud bulk epoxy and composite laminate, experimental and numerical investigations were\ud carried out on compact tension (CT) and double-cantilever-beam (DCB) specimens under\ud mode-I loading. The matrix materials were pure epoxy (DGEBA), 15% LR (CTBN) and 15%\ud CSR modified epoxies. Experimental results and numerical analyses showed that both\ud liquid rubber (LR) and core-shell rubber (CSR) could improve significantly the fracture\ud toughness of pure epoxy (DGEBA). However, the high toughness of these toughened\ud epoxies could not be completely transferred to the interlaminar fracture toughness of the\ud unidirectional carbon fibre reinforced laminate. The main toughening mechanism of CSR in\ud bulk epoxy was the extensive particle cavitation, which greatly released the crack-tip\ud triaxiality and promoted matrix shear plasticity. The poor toughness behavior of CSR in the\ud carbon fibre laminate was thought to be caused by the high constraint imposed by the stiff\ud fibre layers. No particle cavitation had been observed in LR modified epoxy and the main\ud toughening mechanism was merely the large plastic deformation near the crack-tip due to\ud the rubber domains in the matrix which results in a lower yield strength but a higher\ud elongation-to-break