X-Ray Luminosity and Size Relationship of Supernova Remnants in the LMC

International audienceThe Large Magellanic Cloud (LMC) has ∼60 confirmed supernova remnants (SNRs). Because of the known distance, 50 kpc, the SNRs’ angular sizes can be converted to linear sizes, and their X-ray observations can be used to assess X-ray luminosities (L X). We have critically examined the LMC SNRs’ sizes reported in the literature to determine the most plausible sizes. These sizes and the L X determined from XMM-Newton observations are used to investigate their relationship to explore the environmental and evolutionary effects on the X-ray properties of SNRs. Our research provides the following three results. (1) Small LMC SNRs, a few to 10 pc in size, are all Type Ia with L X > 1036 erg s−1. The scarcity of small core-collapse (CC) SNRs is a result of CC SNe exploding in the low-density interiors of interstellar bubbles blown by their massive progenitors during their main-sequence phase. (2) Medium-sized (10–30 pc) CC SNRs show bifurcation in L X, with the X-ray-bright SNRs either in an environment associated with molecular clouds or containing pulsars and pulsar-wind nebulae and the X-ray-faint SNRs being located in low-density interstellar environments. (3) Large (size > 30 pc) SNRs show a trend of L X fading with size, although the scatter is large. The observed relationship between L X and sizes can help constrain models of SNR evolution

Lignin engineering through laccase modification: a promising field for energy plant improvement

Laccase (p-diphenol:dioxygen oxidoreductase, EC 1.10.3.2) is a member of the multicopper oxidases and catalyzes the one-electron oxidation of a wide range of substrates, coupled with the reduction of oxygen to water. It is widely distributed in bacteria, fungi, plants and insects. Laccases are encoded by multigene family, and have been characterized mostly from fungi till now, with abundant industrial applications in pulp and paper, textile, food industries, organic synthesis, bioremediation and nanobiotechnology, while limited researches have been performed in plants, and no application has been reported. Plant laccases share the common molecular architecture and reaction mechanism with fungal ones, despite of difference in redox potential and pH optima. Plant laccases are implicated in lignin biosynthesis since genetic evidence was derived from the Arabidopsis LAC4 and LAC17. Manipulation of plant laccases has been considered as a promising and innovative strategy in plant biomass engineering for desirable lignin content and/or composition, since lignin is the major recalcitrant component to saccharification in biofuel production from lignocellulose, and therefore directly limits the fermentation yields. Moreover, plant laccases have been reported to be involved in wound healing, maintenance of cell wall structure and integrity, and plant responses to environmental stresses. Here, we summarize the properties and functions of plant laccase, and discuss the potential of biotechnological application, thus providing a new insight into plant laccase, an old enzyme with a promising beginning in lignocellulose biofuel production. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13068-015-0331-y) contains supplementary material, which is available to authorized users

HIV and HCV prevalence among entrants to methadone maintenance treatment clinics in China: a systematic review and meta-analysis

<p>Abstract</p> <p>Background</p> <p>Methadone maintenance treatment (MMT) was implemented in China since 2004. It was initiated in 8 pilot clinics and subsequently expanded to 738 clinics by the end of 2011. Numerous individual research studies have been conducted to estimate HIV and HCV prevalence among MMT clients but an overview of the epidemics in relations to MMT remains unclear. The aim of this study is to estimate the magnitude and changing trends of HIV, HCV and HIV-HCV co-infections among entry clients to MMT clinics in China during 2004-2010.</p> <p>Methods</p> <p>Chinese and English databases of literature were searched for studies reporting HIV, HCV and co-infection prevalence among MMT clients in China from 2004 to 2010. The prevalence estimates were summarized through a systematic review and meta-analysis of published literatures.</p> <p>Results</p> <p>Ninety eligible articles were selected in this review (2 in English and 88 in Chinese). Nationally, pooled prevalence of HIV-HCV and HIV-HCV co-infection among MMT clients was 6.0% (95%CI: 4.7%-7.7%), 60.1% (95%CI: 52.8%-67.0%) and 4.6% (95%CI: 2.9%-7.2%), respectively. No significant temporal trend was found in pooled prevalence estimates. Study location is the major contributor of heterogeneities of both HIV and HCV prevalence among drug users in MMT.</p> <p>Conclusions</p> <p>There was no significant temporal trend in HIV and HCV prevalence among clients in MMT during 2004–2010. Prevalence of HCV is markedly higher than prevalence of HIV among MMT clients. It is recommended that health educational programs in China promote the earlier initiation and wider coverage of MMT among injecting drug users (IDUs), especially HIV-infected IDUs.</p