Zr~(4+)/F~– co-doped TiO_2(anatase) as high performance anode material for lithium-ion battery

Zr~(4+) and F~– co-doped TiO_2 with the formula of Ti_(0.97)Zr_(0.03)O_(1.98)F_(0.02) was facilely synthesized by a sol-gel template route.The crystal structure,morphology,composition,surface area,and conductivity were characterized by Raman spectroscopy,energy-dispersive X-ray analysis,scanning electron microscopy,Brunauer-Emmett-Teller measurements,X-ray photoelectron spectroscopy,and electrochemical impedance spectroscopy.The results demonstrate that Zr~(4+)and F~–homogeneously incorporated into TiO_2,forming solid solution with an anatase structure.Ti_(0.97)Zr_(0.03)O_(1.98)F_(0.02)shows outstanding electrochemical properties as Li-ion battery anode in comparison with Ti_(0.97)Zr_(0.03)O_2.In particular,upon 35-fold cycling at 1C-rate Zr~(4+)/F~–co-doped TiO_2delivers a reversible capacity of 163 mAh g~(–1),whereas Zr~(4+)-doped TiO_2gives only 34 mA h g~(–1).Additionally,Zr~(4+)/F~–co-doped TiO_2retains a capacity of 138 mA h g~(–1)during cycling even at 10 C.The enhance performance originates from improved conductivity of Zr~(4+)/F~–co-doped TiO_2material through generation of Ti~(3+)(serving as electron donors)into the crystal lattice and,possibly,due to F-doping blocked the anode surface from attack of HF formed as electrolyte decomposition product.     

Mutations in SIL1 cause Marinesco-Sjögren syndrome, a cerebellar ataxia with cataract and myopathy

SIL1 (also called BAP) acts as a nucleotide exchange factor for the Hsp70 chaperone BiP (also called GRP78), which is a key regulator of the main functions of the endoplasmic reticulum. We found nine distinct mutations that would disrupt the SIL1 protein in individuals with Marinesco-Sj?gren syndrome, an autosomal recessive cerebellar ataxia complicated by cataracts, developmental delay and myopathy. Identification of SIL1 mutations implicates Marinesco-Sj?gren syndrome as a disease of endoplasmic reticulum dysfunction and suggests a role for this organelle in multisystem disorders.     

Mutations in the gene encoding the 3'-5' DNA exonuclease TREX1 cause Aicardi-Goutières syndrome at the AGS1 locus

Aicardi-Goutières syndrome (AGS) presents as a severe neurological brain disease and is a genetic mimic of the sequelae of transplacentally acquired viral infection. Evidence exists for a perturbation of innate immunity as a primary pathogenic event in the disease phenotype. Here, we show that TREX1, encoding the major mammalian 3' --> 5' DNA exonuclease, is the AGS1 gene, and AGS-causing mutations result in abrogation of TREX1 enzyme activity. Similar loss of function in the Trex1(-/-) mouse leads to an inflammatory phenotype. Our findings suggest an unanticipated role for TREX1 in processing or clearing anomalous DNA structures, failure of which results in the triggering of an abnormal innate immune response.     

ISPD loss-of-function mutations disrupt dystroglycan O-mannosylation and cause Walker-Warburg syndrome

Walker-Warburg syndrome (WWS) is clinically defined as congenital muscular dystrophy that is accompanied by a variety of brain and eye malformations. It represents the most severe clinical phenotype in a spectrum of diseases associated with abnormal post-translational processing of a-dystroglycan that share a defect in laminin-binding glycan synthesis1. Although mutations in six genes have been identified as causes of WWS, only half of all individuals with the disease can currently be diagnosed on this basis2. A cell fusion complementation assay in fibroblasts from undiagnosed individuals with WWS was used to identify five new complementation groups. Further evaluation of one group by linkage analysis and targeted sequencing identified recessive mutations in the ISPD gene (encoding isoprenoid synthase domain containing). The pathogenicity of the identified ISPD mutations was shown by complementation of fibroblasts with wild-type ISPD. Finally, we show that recessive mutations in ISPD abolish the initial step in laminin-binding glycan synthesis by disrupting dystroglycan O-mannosylation. This establishes a new mechanism for WWS pathophysiology.     

Regulation of the X-ray luminosity of clusters of galaxies by cooling and supernova feedback.

Clusters of galaxies are thought to contain about ten times as much dark matter as baryonic matter. The dark component therefore dominates the gravitational potential of a cluster, and the baryons confined by this potential radiate X-rays with a luminosity that depends mainly on the gas density in the cluster's core. Predictions of the X-rays' properties based on models of cluster formation do not, however, agree with the observations. If the models ignore the condensation of cooling gas into stars and feedback from the associated supernovae, they overestimate the X-ray luminosity because the density of the core gas is too high. An early episode of uniformly distributed supernova feedback could rectify this by heating the uncondensed gas and therefore making it harder to compress into the core, but such a process seems to require an implausibly large number of supernovae. Here we show how radiative cooling of intergalactic gas and subsequent supernova heating conspire to eliminate highly compressible low-entropy gas from the intracluster medium. This brings the core entropy and X-ray luminosities of clusters into agreement with the observations, in a way that depends little on the efficiency of supernova heating in the early Universe.     

Simulation and validation of modelled sphingolipid metabolism in Saccharomyces cerevisiae

Mathematical models have become a necessary tool for organizing the rapidly increasing amounts of large-scale data on biochemical pathways and for advanced evaluation of their structure and regulation. Most of these models have addressed specific pathways using either stoichiometric or flux-balance analysis, or fully kinetic Michaelis-Menten representations, metabolic control analysis, or biochemical systems theory. So far, the predictions of kinetic models have rarely been tested using direct experimentation. Here, we validate experimentally a biochemical systems theoretical model of sphingolipid metabolism in yeast. Simulations of metabolic fluxes, enzyme deletion and the effects of inositol (a key regulator of phospholipid metabolism) led to predictions that show significant concordance with experimental results generated post hoc. The model also allowed the simulation of the effects of acute perturbations in fatty-acid precursors of sphingolipids, a situation that is not amenable to direct experimentation. The results demonstrate that modelling now allows testable predictions as well as the design and evaluation of hypothetical 'thought experiments' that may generate new metabolomic approaches.     

tRNA splicing endonuclease mutations cause pontocerebellar hypoplasia

Pontocerebellar hypoplasias (PCH) represent a group of neurodegenerative autosomal recessive disorders with prenatal onset, atrophy or hypoplasia of the cerebellum, hypoplasia of the ventral pons, microcephaly, variable neocortical atrophy and severe mental and motor impairments. In two subtypes, PCH2 and PCH4, we identified mutations in three of the four different subunits of the tRNA-splicing endonuclease complex. Our findings point to RNA processing as a new basic cellular impairment in neurological disorders.     

Mutations in genes encoding ribonuclease H2 subunits cause Aicardi-Goutières syndrome and mimic congenital viral brain infection

Aicardi-Goutières syndrome (AGS) is an autosomal recessive neurological disorder, the clinical and immunological features of which parallel those of congenital viral infection. Here we define the composition of the human ribonuclease H2 enzyme complex and show that AGS can result from mutations in the genes encoding any one of its three subunits. Our findings demonstrate a role for ribonuclease H in human neurological disease and suggest an unanticipated relationship between ribonuclease H2 and the antiviral immune response that warrants further investigation.