Microembossing of ultrafine grained Al: microstructural analysis and finite element modelling

Ultra fine grained (UFG) Al-1050 processed by equal channel angular pressing (ECAP) and UFG Al-Mg-Cu-Mn processed by high pressure torsion (HPT) were embossed at both room temperature and 300 °C, with the aim of producing micro-channels. The behaviour of Al alloys during the embossing process was analysed using finite element (FE) modelling. The cold embossing of both Al alloys is characterised by a partial pattern transfer, a large embossing force, channels with oblique sidewalls and a large failure rate of the mould. The hot embossing is characterised by straight channel sidewalls, fully transferred patterns and reduced loads which decrease the failure rate of the mould. Hot embossing of UFG Al-Mg-Cu-Mn produced by HPT shows a potential of fabrication of microelectromechanical system (MEMS) components with micro channels

Study on Safety Control of Composite Roof in Deep Roadway based on Energy Balance Theory

Improving the safety and stability of composite roof in deep roadway is the strong guarantee for safe mining and sustainable development of coal mines. With three roadways of different composite roofs in Hulusu Coal Mine and Menkeqing Coal Mine as the research background, this paper explores the mechanical properties and energy dissipation law of coal-rock structures with different height ratios from the perspective of energy release and dissipation through lab experiments. The results indicate that the key to the stability of coal-rock structures lies in maintaining relatively low dissipation energy. Based on experimental results and the energy balance theory, two support principles were put forward and applied to experimental roadways. The field monitoring results show that the anchoring force on different composite roof displays different characteristics, proving that the work done by the support can adjust timely to the energy release and conversion so as to improve the safety and stability of roadways with different composite roofs. This study provides a reference for the deformation control in deep roadways with composite roofs under similar conditions

Fuzzy PID control of a two-link flexible manipulator

For a flexible manipulator system, the unwanted vibrations deteriorate usually the performance of the system due to the coupling of large overall motion and elastic vibration. This paper focuses on the active vibration control of a two-link flexible manipulator with piezoelectric materials. The multi flexible body dynamics (MFBD) model of the two-link flexible manipulator attached with piezoelectric sensors and actuators is established firstly. Based on the absolute nodal coordinate formulation (ANCF), the motion equations of the manipulator system are derived and motion process and dynamic responses of the system are simulated. According to the time varying feature of system, a fuzzy PID controller is developed to depress the vibration. This controller can tune control gains online accommodating to the variation of the system. Control results obtained by the fuzzy PID control and the conventional PID control indicate that the fuzzy PID controller can effectively suppress the elastic vibration of the manipulator system and performs better than the conventional PID controller

HIV/AIDS, parasites and co-infections: publication patterns in China

BACKGROUND: Since its discovery, HIV/AIDS has arguably captured more attention among the Chinese biomedical research community than most other infectious diseases. Traditional parasitic diseases, on the other hand, are perceived as being increasingly neglected. However, it has long been recognized that interactions between HIV and other infective agents, including parasites, influence the health status of people living with HIV/AIDS. This study aimed at systematically reviewing the Chinese scientific literature on HIV/AIDS and parasites between 1986 and 2006 in order to substantiate or refute these claims, and to highlight neglected research areas. RESULTS: Searching the three largest Chinese scientific literature databases, in the China National Knowledge Infrastructure (CNKI) a total of 24,511 citations dealing with HIV/AIDS and 15,398 parasite-specific publications were identified. Wanfang Data and VIP Information (VIP) contained 15,925 and 13,873 entries dealing with HIV/AIDS, respectively, while 12,043 and 7,068 hits were scored when searching for parasitological references. The number of publications dealing with HIV/AIDS in China increased exponentially from 6 in 1986 to 3,372 in 2006 whereas the publication activity in the field of parasitology was more erratic and lately started to decline. Epidemiology was the most-reported field of endeavor, accounting for 26.0% and 24.6% of the HIV/AIDS and parasitological literature, respectively, while publications dealing with health education only represented 2.9% and 0.7% of all publications, respectively. The total number of Chinese articles focusing on HIV/AIDS and parasite co-infection was 650, with large year-on-year differences in publication numbers. The single-most frequently studied system was HIV-Pneumocystis carinii co-infection. CONCLUSIONS: The present study revealed that in China, the fields of parasitic diseases, especially opportunistic parasitic infections linked with HIV/AIDS, is increasingly neglected. This suggests a need to enhance research in the field of opportunistic parasitic infections and parasitology in general

Comparative metagenomics of Daphnia symbionts

BACKGROUND: Shotgun sequences of DNA extracts from whole organisms allow a comprehensive assessment of possible symbionts. The current project makes use of four shotgun datasets from three species of the planktonic freshwater crustaceans Daphnia: one dataset from clones of D. pulex and D. pulicaria and two datasets from one clone of D. magna. We analyzed these datasets with three aims: First, we search for bacterial symbionts, which are present in all three species. Second, we search for evidence for Cyanobacteria and plastids, which had been suggested to occur as symbionts in a related Daphnia species. Third, we compare the metacommunities revealed by two different 454 pyrosequencing methods (GS 20 and GS FLX). RESULTS: In all datasets we found evidence for a large number of bacteria belonging to diverse taxa. The vast majority of these were Proteobacteria. Of those, most sequences were assigned to different genera of the Betaproteobacteria family Comamonadaceae. Other taxa represented in all datasets included the genera Flavobacterium, Rhodobacter, Chromobacterium, Methylibium, Bordetella, Burkholderia and Cupriavidus. A few taxa matched sequences only from the D. pulex and the D. pulicaria datasets: Aeromonas, Pseudomonas and Delftia. Taxa with many hits specific to a single dataset were rare. For most of the identified taxa earlier studies reported the finding of related taxa in aquatic environmental samples. We found no clear evidence for the presence of symbiotic Cyanobacteria or plastids. The apparent similarity of the symbiont communities of the three Daphnia species breaks down on a species and strain level. Communities have a similar composition at a higher taxonomic level, but the actual sequences found are divergent. The two Daphnia magna datasets obtained from two different pyrosequencing platforms revealed rather similar results. CONCLUSION: Three clones from three species of the genus Daphnia were found to harbor a rich community of symbionts. These communities are similar at the genus and higher taxonomic level, but are composed of different species. The similarity of these three symbiont communities hints that some of these associations may be stable in the long-term

Addressing Parental Smoking in Pediatric Settings of Chinese Hospitals: A Qualitative Study of Parents

This study explored factors associated with SHS exposure from parental smoking in Chinese families and assessed nature of antismoking discussions parents had with their children's pediatricians and how pediatricians might best engage with parents in an effort to reduce children's exposure to SHS. Six focus group discussions (FGDs) were conducted among 33 Chinese parents attending six major hospitals in Guangxi province, China. Most participants (32/33) had family members who smoke, and only 21% had strict restriction on smoking at home. Some parents did not know about health consequences of smoking and effects of SHS exposure on children. Situations that made it especially hard to avoid the child's SHS exposure were having an elderly smoker at home and having a visitor who smoked. Only few parents were asked by pediatricians about child's exposure to SHS at home, but only when child's illness was related to smoking. Parents believed that suggestions coming from pediatricians about smoke-free home and parental quitting would be acceptable to parents and other household members. The findings provide insight into SHS exposure reduction effort among Chinese parents and underscore the demand for pediatrician's engagement in addressing parental tobacco use

Harnessing the wealth of Chinese scientific literature: schistosomiasis research and control in China

The economy of China continues to boom and so have its biomedical research and related publishing activities. Several so-called neglected tropical diseases that are most common in the developing world are still rampant or even emerging in some parts of China. The purpose of this article is to document the significant research potential from the Chinese biomedical bibliographic databases. The research contributions from China in the epidemiology and control of schistosomiasis provide an excellent illustration. We searched two widely used databases, namely China National Knowledge Infrastructure (CNKI) and VIP Information (VIP). Employing the keyword "Schistosoma" () and covering the period 1990–2006, we obtained 10,244 hits in the CNKI database and 5,975 in VIP. We examined 10 Chinese biomedical journals that published the highest number of original research articles on schistosomiasis for issues including languages and open access. Although most of the journals are published in Chinese, English abstracts are usually available. Open access to full articles was available in China Tropical Medicine in 2005/2006 and is granted by the Chinese Journal of Parasitology and Parasitic Diseases since 2003; none of the other journals examined offered open access. We reviewed (i) the discovery and development of antischistosomal drugs, (ii) the progress made with molluscicides and (iii) environmental management for schistosomiasis control in China over the past 20 years. In conclusion, significant research is published in the Chinese literature, which is relevant for local control measures and global scientific knowledge. Open access should be encouraged and language barriers removed so the wealth of Chinese research can be more fully appreciated by the scientific community