DC transformer (DCT) is the main and key equipment of DC distribution network. Multi-ports DCT can connect multiple DC lines or networks at the same time, which has high power supply reliability and is suitable for interconnection equipment among different DC power grids. As an important node in DC distribution network, multi-ports DCT not only operates under normal conditions, but also needs to deal with the impact of DC system fault, among which short circuit fault is the most common one. In this paper, the short-circuit characteristics of multi-ports DCT operating in three different modes are analyzed. The analysis shows that when a single port of the multi-ports DCT fails, the fault ride through of the multi-ports DCT cannot be realized only by changing the operation mode to block the port. This paper investigates a fault ride through strategy based on solid state circuit breaker and feedforward decoupling control method. The simulation results verify the fault characteristics of the multi-ports DCT under different operating modes, and verify the effectiveness of the proposed fault ride through strategy.

Human immunodeficiency virus type 1(HIV-1)-specific CD8 cytotoxic T-lymphocytes(CTL)are essential components of the protective immunity against HIV-1infection.However,due to heterogeneous responses of CTL to HIV-1,our general understanding of CTL efficacy in the context of HIV-1infection remains limited. To better understand the factors that determine the potency of HIV-1specific CTL responses, this study directly investigated the relationship between different functional attributes associated with CTL response at the single cell level by using HIV-1specific CTL clones isolated in vitro. Twelve selected HIV-1CTL clones with various HLA restriction and specific antigen epitopes were comprehensively evaluated by several functional assays(e.g., killing capacity, degranulation, production of multiple cytokines and polyfunctionality, as well as the expression of lytic granule components and exhaustion molecules).Our principal findings were that the killing capacity of the CTL response was most closely associated with their degranulation capacity. Additionally, the killing and the degranulation capacity of CTL was associated with the levels and polyfunctionality of the cytokines secreted later. These findings implicate that multiple functional CTL responses are coordinately regulated and determined.

SUMMARY GB virus C (GBV-C) is frequently identified in patients co-infected with human immunodeficiency virus type 1 (HIV-1) due to the similar transmission routes. However, it remains unclear how these two viruses interact with each other and how one virus affects the replication of the other in the human body. In this study, we performed a case-control study to determine whether GBV-C viraemia could prevent the acquisition of HIV-1 infection, and a cohort study to determine the prevalence, genotypic characteristics and incidence of GBV-C infection in men who have sex with men (MSM) populations in Beijing, China. The prevalence of GBV-C infection in HIV-1-negative subjects was similar to that in HIV-1-positive subjects. Before HIV-1 acquisition, the prevalence of GBV-C was 17·7%, which increased to 27·2% at the acute stage and to 34% at the chronic stage. Genotype 3 was the major genotype of GBV-C in both groups. A significantly positive correlation was observed between the CD4+ T-cell counts and GBV-C viral loads at the acute stage of HIV infection. At the chronic stage (12 months later), this correlation was no longer significant, although it was still positive. Overall, this study demonstrated that pre-existing GBV-C viraemia could not prevent the acquisition of HIV-1 infection and transmission of HIV-1 significantly increased the prevalence of GBV-C viraemia.

SummaryMannose‐binding lectin (MBL) is a key molecule of the innate immune system and a competent to bind carbohydrates of a variety of microorganisms, resulting in complement activation and opsonophagocytosis against various pathogens. However, there is no systemic investigation on the MBL’s role in innate immune responses against HIV‐1 infection among northern Han Chinese. This study investigated the association between MBL and HIV‐1 infection susceptibility among northern Han Chinese. A total of 91 HIV‐1 infected patients and 91 HIV‐1 seronegative healthy individuals were recruited. Six polymorphisms of MBL2 gene were genotyped by pyrosequencing. The quantitative measurement of serum MBL concentration and MBL complex activity were performed by ELISA. The CD4+ T‐cell counts were determined by flow cytometry. The plasma viral loads of 91 HIV‐1 infected patients were determined by bDNA method. The results show that there is an association between MBL and HIV‐1 infection susceptibility among northern Han Chinese. The individuals with B variant, low serum MBL concentration and low MBL complex activity are more susceptible to HIV‐1 infection.

SUMMARY To evaluate the prevalence of hepatitis C virus (HCV) and/or hepatitis B virus (HBV) infections in HIV-infected patients in China, an epidemiological serosurvey was conducted from May 2007 to September 2008 using a random cluster sampling design of infectious disease hospitals in seven high HIV-prevalent provinces (municipalities). Univariate analysis and logistic regression were used to study the determinants of HIV and HBV and/or HCV co-infection. The overall prevalence was 41·83% (95% CI 40·36–43·30) for anti-HCV and 12·49% (95% CI 11·50–13·48) for HBsAg, respectively. The prevalence of anti-HCV and HBsAg varied according to the route of HIV transmission. Compared to those with sexually acquired HIV infection, intravenous drug users and blood donors/recipients had the greatest risk of carrying anti-HCV. Needle sharing and unprotected sexual exposures are important modes of transmission for HBV. Further interventions including health education and harm reduction strategies should be implemented in high-risk populations.

Background The accurate identification of HIV-1-specific T cell responses is important for determining the relationship between immune responses and viral control. Overlapping peptides were synthesized to span gag and nef core 'mosaic' proteins. Mosaic proteins were assembled from fragments of natural sequence using an optimized computational biology method (W. Fischer et al., Nature Medicine, 2007). These proteins resemble natural proteins and were designed to maximize the coverage of potential T cell epitopes. Whilst recent studies have shown that mosaic proteins are highly immunogenic in mice models (W.P. Kong et al., J Virol, 2009), it remains unknown whether mosaics when compared with consensus peptide sets will detect a greater breadth of T cell responses in natural HIV-1 infection.