No abstract

No abstract

However, the shuttle effect triggered by the dissolution of long-chain polysulfides (Li 2 S x , 4 ≤ x ≤ 8) results in severe active sulfur loss and fast capacity decay, which severely hinders the commercial application of these batteries. [4,6] Fundamentally, these problems are a result of the slow and complex sulfur reduction reaction (SRR), i.e., the sluggish kinetic transformation of soluble lithium polysulfides (LiPSs) to insoluble Li 2 S 2 /Li 2 S (discharge products). [7,8] Therefore, exploring effective strategies to accelerate the conversion of LiPSs from the liquid to the solid state is essential to boost the practical energy density and lifespan of lithium-sulfur batteries. [9,10] Considerable efforts have been devoted to addressing the aforementioned problems, typically by using sulfides, nitrides, phosphides as host materials to trap the LiPSs in the sulfur cathode. [11][12][13][14] However, these physical or electrostatic confinement/trapping methods fail to entirely avoid the dissolution and accumulation of LiPSs in the electrolyte. [8] A catalytic approach has therefore been proposed as a more proactive solution to cure the shuttle effect by accelerating the conversion of the liquid-phase long-chain LiPSs into final solid-phase discharge products. [15,16] Like the oxygen Seeking an electrochemical catalyst to accelerate the liquid-to-solid conversion of soluble lithium polysulfides to insoluble products is crucial to inhibit the shuttle effect in lithium-sulfur (Li-S) batteries and thus increase their practical energy density. Mn-based mullite (SmMn 2 O 5 ) is used as a model catalyst for the sulfur redox reaction to show how the design rules involving lattice matching and 3d-orbital selection improve catalyst performance. Theoretical simulation shows that the positions of Mn and O active sites on the (001) surface are a good match with those of Li and S atoms in polysulfides, resulting in their tight anchoring to each other. Fundamentally, dz 2 and dx 2 −y 2 around the Fermi level are found to be crucial for strongly coupling with the p-orbitals of the polysulfides and thus decreasing the redox overpotential. Following the theoretical calculation, SmMn 2 O 5 catalyst is synthesized and used as an interlayer in a Li-S battery. The resulted battery has a high cycling stability over 1500 cycles at 0.5 C and more promisingly a high areal capacity of 7.5 mAh cm −2 is achieved with a sulfur loading of ≈5.6 mg cm −2 under the condition of a low electrolyte/sulfur (E/S) value ≈4.6 µL mg −1 .

The coordination of carbon and nitrogen metabolism is essential for bacteria to adapt to nutritional variations in the environment, but the underlying mechanism remains poorly understood. In autotrophic cyanobacteria, high CO levels favor the carboxylase activity of ribulose 1,5 bisphosphate carboxylase/oxygenase (RuBisCO) to produce 3-phosphoglycerate, whereas low CO levels promote the oxygenase activity of RuBisCO, leading to 2-phosphoglycolate (2-PG) production. Thus, the 2-PG level is reversely correlated with that of 2-oxoglutarate (2-OG), which accumulates under a high carbon/nitrogen ratio and acts as a nitrogen-starvation signal. The LysR-type transcriptional repressor NAD(P)H dehydrogenase regulator (NdhR) controls the expression of genes related to carbon metabolism. Based on genetic and biochemical studies, we report here that 2-PG is an inducer of NdhR, while 2-OG is a corepressor, as found previously. Furthermore, structural analyses indicate that binding of 2-OG at the interface between the two regulatory domains (RD) allows the NdhR tetramer to adopt a repressor conformation, whereas 2-PG binding to an intradomain cleft of each RD triggers drastic conformational changes leading to the dissociation of NdhR from its target DNA. We further confirmed the effect of 2-PG or 2-OG levels on the transcription of the NdhR regulon. Together with previous findings, we propose that NdhR can sense 2-OG from the Krebs cycle and 2-PG from photorespiration, two key metabolites that function together as indicators of intracellular carbon/nitrogen status, thus representing a fine sensor for the coordination of carbon and nitrogen metabolism in cyanobacteria.

Concentrations of organic carbon (OC) and elemental carbon (EC) in atmospheric particles were measured in Tianjin during January, April, July and October in 2008. The 24-h PM 2.5 (particles with aerodynamic diameters less than 2.5 micrometer [μm]) and PM 10 (particles with aerodynamic diameters less than 10 micrometer [μm]) samples were simultaneously collected every day during sampling periods. These samples were analyzed for OC/EC by thermal/optical reflectance (TOR) following the Interagency Monitoring of Protected Visual Environments (IMPROVE) protocol. The annual average concentration was 109.8 ± 48.5 μg/m 3 in PM 2.5 , and 196.2 ± 86.1 μg/m 3 in PM 10 , respectively. The average ratio of PM 2.5 /PM 10 was 57.9%, indicating the PM 2.5 had been one of the main contaminations affecting urban atmospheric environmental quality in Tianjin. The concentrations of OC and EC in PM 2.5 and PM 10 were all relatively higher in winter and fall and lower in summer and spring. This seasonal variation could be attributed to the cooperative effects of changes in emission rates and seasonal meteorological conditions. The annual average concentration of the estimated secondary organic carbon (SOC) was 14.9 μg/m 3 and occupied 61.7% of the total OC in PM 2.5 , while those in PM 10 were 23.4 μg/m 3 and 61.2%, respectively, indicating SOC had been an important contributor to organic aerosol in Tianjin. The distribution of eight carbon fractions (OC1, OC2, OC3, OC4, EC1, EC2, EC3 and OP) was also reported and found that the biomass burning, coal-combustion and motor-vehicle exhaust were all contributed to the carbonaceous particles in Tianjin.

Environmental and genetic factors are thought to be involved in the pathogenesis of autoimmune thyroid diseases (AITD), which include Graves' disease, Hashimoto's thyroiditis. Polymorphisms of vitamin D receptor (VDR) were implicated in AITDs risk. To date, many studies have evaluated the association between a functional polymorphism in the VDR gene and AITDs risk; however, the result is still ambiguous and inconclusive. To address the association of VDR gene FokI (rs10735810), TaqI (rs731236), BsmI (rs1544410), and ApaI (rs7975232) polymorphisms with AITD risk by meta-analysis. By searching the relevant literature, a total of eight studies were identified and meta-analyzed. HWE for each study are checked. Crude odds ratios (OR) with 95 % confidence intervals (CIs) were used to assess the strength of association in the allele polymorphism, codominant model, dominant model, and recessive model. The result indicates that the BsmI or TaqI polymorphisms is significantly associated with AITD risk (OR = 0.801 95 % CI 0.705, 0.910, Pz = 0.001 for B vs. b; OR = 0.854, 95 % CI 0.757, 0.963, Pz = 0.010 for t vs. T), while the ApaI or FokI polymorphism do not. In the subgroup analysis in Europeans, the decreased risk of AITD remained for the B or t variant. This gene-based analysis indicates that, based on current evidence from published studies, the cumulative effect of BsmI or TaqI polymorphisms in VDR is significantly associated with AITD.

No abstract

BackgroundThrough the whole life of eukaryotes, autophagy plays an important role in various biological events including development, differentiation and determination of lifespan. A full set of genes and their encoded proteins of this evolutionarily conserved pathway have been identified in many eukaryotic organisms from yeast to mammals. However, this pathway in the insect model organism, the silkworm Bombyx mori, remains poorly investigated.ResultsBased on the autophagy pathway in several model organisms and a series of bioinformatic analyses, we have found more than 20 autophagy-related genes from the current database of the silkworm Bombyx mori. These genes could be further classified into the signal transduction pathway and two ubiquitin-like pathways. Using the mRNA extracted from the silkgland, we cloned the full length cDNA fragments of some key genes via reverse transcription PCR and 3' rapid amplification of cDNA ends (RACE). In addition, we found that the transcription levels of two indicator genes BmATG8 and BmATG12 in the silkgland tend to be increased from 1st to 8th day of the fifth instar larvae.ConclusionBioinformatics in combination with RT-PCR enable us to remodel a preliminary pathway of autophagy in the silkworm. Amplification and cloning of most autophagy-related genes from the silkgland indicated autophagy is indeed an activated process. Furthermore, the time-course transcriptional profiles of BmATG8 and BmATG12 revealed that both genes are up-regulated along the maturation of the silkgland during the fifth instar. These findings suggest that the autophagy should play an important role in Bombyx mori silkgland.