BackgroundHemorrhagic fever with renal syndrome (HFRS) is caused by different hantaviruses within the Bunyaviridae family. HFRS is a fulminant, infectious disease that occurs worldwide and is endemic in all 31 provinces of China. Since the first HFRS case in Hubei Province was reported in 1957, the disease has spread across the province and Hubei has become one of the seriously affected areas in China with the greatest number of reported HFRS cases in the 1980's. However, the epidemic characteristics of HFRS in Hubei are still not entirely clear and long-term, systematic investigations of this epidemic area have been very limited.MethodsThe spatiotemporal distribution of HFRS was investigated using data spanning the years 1980 to 2009. The annual HFRS incidence, fatality rate and seasonal incidence between 1980 and 2009 were calculated and plotted. GIS-based spatial analyses were conducted to detect the spatial distribution and seasonal pattern of HFRS. A spatial statistical analysis, using Kulldorff's spatial scan statistic, was performed to identify clustering of HFRS.ResultsA total of 104,467 HFRS cases were reported in Hubei Province between 1980 and 2009. Incidence of and mortality due to HFRS declined after the outbreak in 1980s and HFRS cases have been sporadic in recent years. The locations and scale of disease clusters have changed during the three decades. The seasonal epidemic pattern of HFRS was characterized by the shift from the unimodal type (autumn/winter peak) to the bimodal type.ConclusionsSocioeconomic development has great influence on the transmission of hantaviruses to humans and new epidemic characteristics have emerged in Hubei Province. It is necessary to reinforce preventative measures against HFRS according to the newly-presented seasonal variation and to intensify these efforts especially in the urban areas of Hubei Province.

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Bioflocculants of Chlamydomonas reinhardtii were investigated under axenic conditions. C. reinhardtii was found to produce significant amounts of bioflocculants. Flocculating activity by C. reinhardtii began in the linear phase of growth and continued until the end of the stationary phase. The highest flocculating efficiency of the culture broth was 97.06%. The purified C. reinhardtii bioflocculant was composed of 42.1% (w/w) proteins, 48.3% carbohydrates, 8.7% lipids, and 0.01% nucleic acid. The optimum condition for bioflocculant production of C. reinhardtii was as follows: under temperature of 15°C to 25°C, pH 6-10 and illumination of 40-60 μmol photons m −2 s −1 . The bioflocculants produced by C. reinhardtii showed maximum activity in pH ranges from 2 to 10. The flocculating activity was significantly enhanced by the addition of CaCl 2 as a coflocculant at an optimal concentration of 4.5 mM.

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Sophisticated three-dimensional (3D) forms are expected to be one of the significant development trends in nextgeneration microelectronics because of their capabilities of rendering substantially enhanced performances, a high degree of integration, and novel functionalities. To date, a diversity of manufacturing methods has been developed for 3D microelectronic devices with different structural and functional features. Most of these methods fall into two categories, i.e., micromanufacturing technologies and mechanically guided 3D assembly approaches. From this perspective, we review the different manufacturing methods and their specific features as well as their limitations. At present, there is still no universal method that can deterministically form 3D microelectronic devices with very high geometric complexity and nanoscale precision. We offer an outlook on future developments in the manufacturing of 3D multifunctional microelectronics devices and provide some perspectives on the remaining challenges as well as possible solutions. Mechanically guided 3D assembly based on compressive buckling is proposed as a versatile platform that can be merged with micromanufacturing technologies and/or other assembly methods to provide access to microelectronic devices with more types of integrated functions and highly increased densities of functional components.

Power Factor Correction (PFC) converters are widely used in engineering. A classical PFC control circuit employs two complicated feedback control loops and a multiplier, while the One-Cycle-Controlled (OCC) PFC converter has a simple control circuit. In OCC PFC converters, the voltage loop is implemented with a PID control and the multiplier is not needed. Although linear theory is used in designing the OCC PFC converter control circuit, it cannot be used in predicting non-linear phenomena in the converter. In this paper, a non-linear model of the OCC PFC Boost converter is proposed based on the double averaging method. The line frequency instability of the converter is predicted by studying the DC component, the first harmonic component and the second harmonic component of the main circuit and the control circuit. The effect of the input voltage and the output capacitance on the stability of the converter is studied. The correctness of the proposed model is verified with numerical simulations and experimental measurements.

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