Utilizing an ionic liquid for synthesizing a soft matter polymer ``gel'' electrolyte for high rate capability lithium-ion batteries

A cross-linked polymer ``gel'' electrolyte obtained from free radical polymerization of a vinyl monomer (acrylonitrile; AN) in a room temperature ionic liquid electrolyte (N,N-methyl butyl pyrrolidinium-bis (trifluoromethanesulphonyl)imide-lithium bis(trifluoromethanesulphonyl) imide;LiTFSI-[Py(1,4)-TFSI]) for application in high rate capability rechargeable lithium-ion batteries is discussed here. This is a novel alternative compared to the often employed approach of using a molecular liquid as the medium for performing the polymerization reaction. The polymer ``gel'' electrolytes (AN:Py(1,4)-TFSI = 0.16-0.18, w/w) showed remarkable compliable mechanical strength and higher thermal stability compared to LiTFSI-[Py(1,4)-TFSI]. Despite two orders increase in magnitude of viscosity of polymer ``gels'', the room temperature ionic conductivity of the ``gels'' (1.1 x 10(-3)-1.7 x 10(-3) Omega(-1) cm(-1)) were nearly identical to that of the ionic liquid (1.8 x 10(-3) Omega(-1) cm(-1)). The present ``gel'' electrolytes did not exhibit any ageing effects on ionic conductivity similar to the conventional polymer gel electrolytes (e.g. high molecular weight polymer + salt + high dielectric constant molecular solvent). The disorder (ionic liquid) to a relative order (cross-linked polymer electrolyte) transformation does not at all influence the concentration of conducting species. The polymer framework is still able to provide efficient pathways for fast ion transport. Unlike the ionic liquid which is impossible to assemble without a conventional separator in a cell, the polymer ``gel'' electrolyte could be conveniently assembled without a separator in a Li vertical bar lithium iron phosphate (LiFePO(4)) cell. Compared to the ionic liquid, the ``gel'' electrolyte showed exceptional cyclability and rate capability (current density: 35-760 mA g(-1) with LiFePO(4) electronically wired with carbon (amorphous or multiwalled nanotube [MWCNT]).

Mutations in WDR62, encoding a centrosomal and nuclear protein, in Indian primary microcephaly families with cortical malformations

Primary microcephaly is an autosomal recessive disorder characterized by smaller than normal brain size and mental retardation. It is genetically heterogeneous with seven loci: MCPH1-MCPH7. We have previously reported genetic analysis of 35 families, including the identification of the MCPH7 gene STIL. Of the 35 families, three families showed linkage to the MCPH2 locus. Recent whole-exome sequencing studies have shown that the WDR62 gene, located in the MCPH2 candidate region, is mutated in patients with severe brain malformations. We therefore sequenced the WDR62 gene in our MCPH2 families and identified two novel homozygous protein truncating mutations in two families. Affected individuals in the two families had pachygyria, microlissencephaly, band heterotopias, gyral thickening, and dysplastic cortex. Using immunofluorescence study, we showed that, as with other MCPH proteins, WDR62 localizes to centrosomes in A549, HepG2, and HaCaT cells. In addition, WDR62 was also localized to nucleoli. Bioinformatics analysis predicted two overlapping nuclear localization signals and multiple WD-40 repeats in WDR62. Two other groups have also recently identified WDR62 mutations in MCPH2 families. Our results therefore add further evidence that WDR62 is the MCPH2 gene. The present findings will be helpful in genetic diagnosis of patients linked to the MCPH2 locus.

Subdiffusion as a model of transport through the nuclear pore complex

Cargo transport through the nuclear pore complex continues to be a subject of considerable interest to experimentalists and theorists alike. Several recent studies have revealed details of the process that have still to be fully understood, among them the apparent nonlinearity between cargo size and the pore crossing time, the skewed, asymmetric nature of the distribution of such crossing times, and the non-exponentiality in the decay profile of the dynamic autocorrelation function of cargo positions. In this paper, we show that a model of pore transport based on subdiffusive particle motion is in qualitative agreement with many of these observations. The model corresponds to a process of stochastic binding and release of the particle as it moves through the channel. It suggests that the phenylalanine-glycine repeat units that form an entangled polymer mesh across the channel may be involved in translocation, since these units have the potential to intermittently bind to hydrophobic receptor sites on the transporter protein. (C) 2011 American Institute of Physics. [doi:10.1063/1.3651100]

Investigation on the High Vacuum Tribological Characteristics of Surface Treated Nuclear Grade Stainless Steel Type AISI 316 LN at 25 to 500 degrees C

Although some researchers have published friction and wear data of Plasma Nitride (PN) coatings, the tribological behavior of PN/PN Pairs in high vacuum environment has not been published so far In order to bridge this knowledge gap, tribological tests under dry conditions have been conducted on PN/PN Pairs for varying temperatures of 25, 200, 400 and 500 degrees C in high vacuum (1.6 x 10(-4) bar) environment. The PN coatings showed good wear resistance layer on the ring surface. The PN coatings were removed only from the pin surface for all the tests since it contacts at a point. The friction and wear were low at lower temperatures and it eliminated adhesion between the contact surfaces until the coating was completely removed from the pin surface. (C) 2011 Journal of Mechanical Engineering. All rights reserved.

Experimental implementation of quantumUlam’s problem in a nuclear magnetic resonance quantum information processor

The Ulam’s problem is a two person game in which one of the player tries to search, in minimum queries, a number thought by the other player. Classically the problem scales polynomially with the size of the number. The quantum version of the Ulam’s problem has a query complexity that is independent of the dimension of the search space. The experimental implementation of the quantum Ulam’s problem in a Nuclear Magnetic Resonance Information Processor with 3 quantum bits is reported here.

Functional regulation of PVBV Nuclear Inclusion protein-a protease activity upon interaction with Viral Protein genome-linked and phosphorylation

Regulation of NIa-Pro is crucial for polyprotein processing and hence, for successful infection of potyviruses. We have examined two novel mechanisms that could regulate NIa-Pro activity. Firstly, the influence of VPg domain on the proteolytic activity of NIa-Pro was investigated. It was shown that the turnover number of the protease increases when these two domains interact (as: two-fold; trans: seven-fold) with each other. Secondly, the protease activity of NIa-Pro could also be modulated by phosphorylation at Ser129. A mutation of this residue either to aspartate (phosphorylation-mimic) or alanine (phosphorylation-deficient) drastically reduces the protease activity. Based on these observations and molecular modeling studies, we propose that interaction with VPg as well as phosphorylation of Ser129 could relay a signal through Trp143 present at the protein surface to the active site pocket by subtle conformational changes, thus modulating protease activity of NIa-Pro. (C) 2011 Elsevier Inc. All rights reserved.

Critical behavior at depinning of driven disordered vortex matter in 2H-NbS2

We report unusual jamming in driven ordered vortex flow in 2H-NbS2. Reinitiating movement in these jammed vortices with a higher driving force and halting it thereafter once again with a reduction in drive leads to a critical behavior centered around the depinning threshold via divergences in the lifetimes of transient states, validating the predictions of a recent simulation study Reichhardt and Olson Reichhardt, Phys. Rev. Lett. 103, 168301 (2009)] which also pointed out a correspondence between plastic depinning in vortex matter and the notion of random organization proposed Corte et al., Nat. Phys. 4, 420 (2008)] in the context of sheared colloids undergoing diffusive motion.

Constraints on axino warm dark matter from X-ray observation at the Chandra telescope and SPI

A sufficiently long lived warm dark matter could be a source of X-rays observed by satellite based X-ray telescopes. We consider axinos and gravitinos with masses between 1 keV and 100 keV in supersymmetric models with sin all R-parity violation. We show that axino dark matter receives significant constraints from X-ray observations of Chandra and SPI, especially for the lower end of the allowed range of the axino decay constant f(a), while the gravitino dark matter remains unconstrained.

A drop of active matter

We study theoretically the hydrodynamics of a fluid drop containing oriented filaments endowed with active contractile or extensile stresses and placed on a solid surface. The active stresses alter qualitatively the wetting properties of the drop, leading to new spreading laws and novel static drop shapes. Candidate systems for testing our predictions include cytoskeletal extracts with motors and ATP, suspensions of bacteria or pulsatile cells, or fluids laden with artificial self-propelled colloids.

Interplay of localized and itinerant character of Ru ions: Tl2Ru2O7 versus Hg2Ru2O7

We carry out a comparative study of the electronic structure of two pyrochlore ruthenate compounds, Tl2Ru2O7 and Hg2Ru2O7, in terms of first principles calculations. Our study reveals the Ru d electrons in Hg2Ru2O7 to be much more delocalized compared to that in Tl2Ru2O7. The subtle change in the Ru-d bandwidths in the two compounds, triggered by the differences in Hg 5d-Ru 4d hybridization compared to that of Tl 5d-Ru 4d, bring in the observed differences in behavior. Our study further shows that the development of long range noncollinear antiferromagnetic structure at low temperature is sufficient to produce the insulating solution in Hg2Ru2O7, in line with the prediction from recent nuclear magnetic resonance study.

Presence of dark energy and dark matter: does cosmic acceleration signifies a weak gravitational collapse?

In this work the collapsing process of a spherically symmetric star, made of dust cloud, in the background of dark energy is studied for two different gravity theories separately, i.e., DGP Brane gravity and Loop Quantum gravity. Two types of dark energy fluids, namely, Modified Chaplygin gas and Generalised Cosmic Chaplygin gas are considered for each model. Graphs are drawn to characterize the nature and the probable outcome of gravitational collapse. A comparative study is done between the collapsing process in the two different gravity theories. It is found that in case of dark matter, there is a great possibility of collapse and consequent formation of Black hole. In case of dark energy possibility of collapse is far lesser compared to the other cases, due to the large negative pressure of dark energy component. There is an increase in mass of the cloud in case of dark matter collapse due to matter accumulation. The mass decreases considerably in case of dark energy due to dark energy accretion on the cloud. In case of collapse with a combination of dark energy and dark matter, it is found that in the absence of interaction there is a far better possibility of formation of black hole in DGP brane model compared to Loop quantum cosmology model.

Novel ATPase activity of the polyprotein intermediate, Viral Protein genome-linked-Nuclear Inclusion-a protease, of Pepper vein banding potyvirus

Potyviruses temporally regulate their protein function by polyprotein processing. Previous studies have shown that VPg (Viral Protein genome-linked) of Pepper vein banding virus interacts with the NIa-Pro (Nuclear Inclusion-a protease) domain, and modulates the kinetics of the protease. In the present study, we report for the first time that VPg harbors the Walker motifs A and B, and the presence of NIa-Pro, especially in cis (cleavage site (E191A) VPg-Pro mutant), is essential for manifestation of the ATPase activity. Mutation of Lys47 (Walker motif A) and Asp88:Glu89 (Walker motif B) to alanine in E191A VPg-Pro lead to reduced ATPase activity, confirming that this activity was inherent to VPg. We propose that potyviral VPg, established as an intrinsically disordered domain, undergoes plausible structural alterations upon interaction with globular NIa-Pro which induces the ATPase activity. (C) 2012 Elsevier Inc. All rights reserved.

Nuclear targeting terpyridine iron(II) complexes for cellular imaging and remarkable photocytotoxicity

Iron(II) complexes Fe(L)(2)](2+) as perchlorate (1-3) and chloride (1a-3a) salts, where L is 4'-phenyl-2,2':6',2 `'-terpyridine (phtpy in 1, 1a), 4'-(9-anthracenyl)-2,2':6',2 `'-terpyridine (antpy in 2, 2a) and 4'-(1-pyrenyl)-2,2':6',2 `'-terpyridine (pytpy in 3, 3a), were prepared and their photocytotoxicity studied. The diamagnetic complexes 1-3 having an FeN6 core showed an Fe(III)-Fe(II) redox couple near 1.0 V vs. saturated calomel electrode in MeCN-0.1 M tetrabutylammonium perchlorate. Complexes 2 and 3, in addition, displayed a quasi-reversible ligand-based redox process near 0.0 V. The redox and spectral properties are rationalized from the theoretical studies. The complexes bind to DNA in a partial intercalative mode. The pytpy complex efficiently photo-cleaves DNA in green light via superoxide and hydroxyl radical formation. The antpy and pytpy complexes exhibited a remarkable photocytotoxic effect in HeLa cancer cells (IC50, similar to 9 mu M) in visible light (400-700 nm), while remaining essentially nontoxic in dark (IC50, similar to 90 mu M). Formation of reactive oxygen species (ROS) inside the HeLa cells was evidenced from the fluorescence enhancement of dichlorofluorescein upon treatment with the pytpy complex followed by photo-exposure. The antpy and pytpy complexes were used for cellular imaging. Confocal imaging and dual staining study using propidium iodide (PI) showed nuclear localization of the complexes. (c) 2012 Elsevier Inc. All rights reserved.

Supersymmetric Chern-Simons theories with vector matter

In this paper we discuss SU(N) Chern-Simons theories at level k with both fermionic and bosonic vector matter. In particular we present an exact calculation of the free energy of the N = 2 supersymmetric model (with one chiral field) for all values of the `t Hooft coupling in the large N limit. This is done by using a generalization of the standard Hubbard-Stratanovich method because the SUSY model contains higher order polynomial interactions.