A chemical approach to an understanding of the fast ion conduction in silver iodide-silver oxysalt glasses

A number of AgI based fast ion conducting glasses, with a general formula AgI---Ag2O---MxOy (MxOy=MoO3, SeO3, WO3, V2O5, P2O5, GeO2, B2O3, As2O3, CrO3) have been studied. A chemical approach is made to investigate the origin of fast ion conduction in these glasses. An index known as Image tructural Image npinning Image umber, SUN (S), has been defined for the purpose, based on the unscreened nuclear charge of silver ions and the equilibrium lectronegativities of the halide-oxyanion matrix in these glasses. The variation of the glass transition temperature, Tg, conductivity, σ, and the energy of activation, Ea, with the concentration of AgI are discussed in the light of the structural unpinning number. Conductivities increase uniformly in any given glass series as a smooth function of S and level off at very high values. The entire range of conductivity appears to vary as ln Image , where ln σ0 corresponds roughly to the conductivity of the hypothetical AgI glass and “a” is a constant which could be obtained as the slope in the graph of ln Ea versus S. It is suggested that the increase in the concentration of AgI beyond 75–80 mole% in the glass is not advantageous from the conductivity point of view.

Surface diffusion driven nanoshell formation by controlled sintering of mesoporous nanoparticle aggregates

We report a general method for the synthesis of hollow structures of a variety of functional inorganics by partial sintering of mesoporous nanocrystal aggregates. The formation of a thin shell initiates the transport of mass from the interior leading to growth of the shell. The principles are general and the hollow structures thus produced are attractive for many applications including catalysis, drug delivery and biosensing.

A singularity-free cosmological model in ECSK theory

In the framework of the ECSK [Einstein-Cartan-Sciama-Kibble] theory of cosmology, a scalar field nonminimally coupled to the gravitational field is considered. For a Robertson-Walker open universe (k=0) in the radiation era, the field equations admit a singularity-free solution for the scale factor. In theory, the torsion is generated through nonminimal coupling of a scalar field to the gravitation field. The nonsingular nature of the cosmological model automatically solves the flatness problem. Further absence of event horizon and particle horizon explains the high degree of isotropy, especially of 2.7-K background radiation.

Unified large and small signal non-quasi-static model for long channel symmetric DG MOSFET

We propose a unified model for large signal and small signal non-quasi-static analysis of long channel symmetric double gate MOSFET. The model is physics based and relies only on the very basic approximation needed for a charge-based model. It is based on the EKV formalism Enz C, Vittoz EA. Charge based MOS transistor modeling. Wiley; 2006] and is valid in all regions of operation and thus suitable for RF circuit design. Proposed model is verified with professional numerical device simulator and excellent agreement is found. (C) 2010 Elsevier Ltd. All rights reserved.

Laser Surface Alloying of a Creep Resistant Magnesium Alloy MRI 230D with Al and Al2O3

A creep resistant permanent mould cast Mg alloy MRI 230D was laser surface alloyed with Al and a mixture of Al and Al2O3 using pulsed Nd:YAG laser irradiation at four different scan speeds in order to improve the corrosion and wear resistance. The microstructure, corrosion and wear behavior of the laser surface alloyed material is reported in this manuscript. The coating comprised of a featureless microstructure with cellular-dendritic microstructure near the interface and exhibited good interfacial bonding. A few solidification cracks reaching down to substrate were also observed. The two step coating with Al followed by a mixture of Al and Al2O3 exhibited a slightly better corrosion resistance than the single step coating with Al. In the long run, however, corrosion resistance of both the coatings became comparable to the as-cast alloy. The corroded surface of the laser surface alloyed specimens revealed a highly localized corrosion. The laser surface alloyed specimens exhibited an improvement in wear resistance. The laser scan speed did not exhibit a monotonic trend either in corrosion or wear resistance.

Experimental evaluation of the aeroacoustic characteristics of a source of pulsating gas flow

Amongv arioums ethodtsh,e t ransmissliionne o r thei mpedantcueb em ethohda sb eenm ospt opulafro r thee xperimenetavla luatioonf thea cousticiaml pedanocef a terminatioTnh. ee xistinmg ethodisn,c luding theo nesre porteeda rlierb, y thea uthorrse quirleo catioonf thes oundp ressumrei nima nd/orm axima, or elsem akeu se0 f somei terativep rocedureTsh. e presenpt aperd ealsw ith a methodo f analysios f standinwga vews hichd oesn otd epenodn anyo f thesein volvepdr ocedureIts i.s applicabtloe thec aseo f stationarays w ella sm ovingm ediaI.t enableosn to evaluatteh e impedancoef anyp assivbel ackb ox,a s well as the aeroacoustcich aracteristicosf a sourceo f pulsatingg asf low, with the leaste xperimentawl ork andc omputatiotinm ea ndw itht hee xtraa dvantagoef usinga givenim pedanctueb ef or wavelengtahss largea s fourt imesit s lengthA. methodo f externaml easuremenntost, involvinugs eo f anyi mpedance tubef, or evaluatintgh ea eroacouscthica racteristoicf as sourcoef pulsatingga sf lowi s alsod ealtw ith, based on the definition of attenuation or insertion loss of a muffler.

Mixed ligand cobalt(III) complexes of tetradentate N,N′-ethylenebis(acetylacetonimine) and flexidentate isonitroso-β-diketones and isonitrosomonoketones

A series of mixed ligand cobalt(III) complexes having the general formula Co(EA)X [where EA = dianion of N,N′-ethylenebis(acetylacetonimine) and X = anion of isonitroso-acetylacetone, IAA; isonitrosobenzoylacetone, IBA; isonitrosodibenzoylmethane, IDBM; isonitrosoethylacetoacetate, IEA; isonitrosoacetoacetanillide, IAN; isonitrosoethylmethylketone, IEMK; isonitrosobenzylmethylketone, IBMK and isonitrosopropiophenone, IPP] have been synthesised and characterised. A facial-cis-β structure (cis with respect to the coordinated two oxygen atoms of EA) with N,N,N,O,O,O ligational environment has been assigned for the complexes. The characterisation of the complexes has been based upon chemical analysis, electrical conductivity, magnetic moment, IR, PMR and electronic spectra.

Electronic excitations and alternation of conjugated polymers

The electronic excitations and fluorescence of conjugated polymers are related to large or small alternation ? of the transfer integrals t(1 ± ?) along the backbone. The fluorescence of polysilanes (PSs) and poly (para-phenylenevinylene (PPV) is linked to large ?, which places the one-photon gap Eg below the lowest two-photon gap Ea and reduces distortions due to electron-phonon (e-p) coupling. In contrast to small ? not, vert, similar 0.1 in ?-conjugated polymers, such as polyacetylene (PA), para-conjugated phenyls lead to an extended ?-system with increased alternation, to states localized on each ring and to charge-transfer excitations between them. Surprisingly good agreement is found between semiempirical parametric method 3 (PM3) bond lengths and exact Pariser-Parr-Pople (PPP) ?-bond orders for trans-stilbene, where the PPV bipolarons are confined to two phenyls. Stilbene spectra are consistent with increased alternation and small e-p distortions.

Proton NMR study of molecular dynamics in ammonium tribromo stannate (NH4SnBr3)

The proton second moment M2 and spin-lattice relaxation time T1 have been measured in ammonium tribromo stannate (NH4SnBr3) in the temperature range 77–300 K, to determine the ammonium dynamics. The continuous wave signal is strong and narrow at 77 and 300 K but has revealed an interesting intensity anomaly between 210 and 125 K. T1 shows a maximum (13 s) around 220 K. No minimum in the T1 vs 1000/T plot was observed down to 77 K. M2 and T1 results are interpreted in terms of NH+4 ion dynamics. The activation energy Ea for NH+4 ion reorientation is estimated to be 1.4 kcal mol−1.

Highly dispersed ultrafine Pt and PtRu nanoparticles on graphene: formation mechanism and electrocatalytic activity

We demonstrate a robust strategy for obtaining a high dispersion of ultrafine Pt and PtRu nanoparticles on graphene by exploiting the nucleation of a metal precursor phase on graphite oxide surfaces. Our method opens up new possibilities to engineer graphene-based hybrids for applications in multifunctional nanoscale devices.

Inhibition of nuclear protein import by a monoclonal antibody against a novel class of nuclear pore proteins

Nuclear import of proteins is mediated by the nuclear pore complexes in the nuclear envelope and requires the presence of a nuclear localization signal (NLS) on the karyophilic protein. In this paper, we describe studies with a monoclonal antibody, Mab E2, which recognizes a class of nuclear pore proteins of 60-76 kDa with a common phosphorylated epitope on rat nuclear envelopes. The Mab Ea-reactive proteins fractionated with the relatively insoluble pore complex-containing component of the envelope and gave a finely punctate pattern of nuclear staining in immunofluorescence assays. The antibody did not bind to any cytosolic proteins. Mab E2 inhibited the interaction of a simian virus 40 large T antigen NLS peptide with a specific 60-kDa NLS-binding protein from rat nuclear envelopes in photoaffinity labeling experiments. The antibody blocked the nuclear import of NLS-albumin conjugates in an in vitro nuclear transport assay with digitonin-permeabilized cells, but did not affect passive diffusion of a small nonnuclear protein, lysozyme, across the pore. Mab E2 may inhibit protein transport by directly interacting with the 60-kDa NLS-binding protein, thereby blocking signal-mediated nuclear import across the nuclear pore complex. (C) 1994 Academic Press, Inc.

Thermal Stability of Spherical Nanoporous Aggregates and Formation of Hollow Structures by Sintering-A Phase-Field Study

Nanoporous structures are widely used for many applications and hence it Is important to investigate their thermal stability. We study the stability of spherical nanoporous aggregates using phase-field simulations that explore systematically the effect of grain boundary diffusion, surface diffusion, and grain boundary mobility on the pathways for microstructural evolution. Our simulations for different combinations of surface and GB diffusivity and GB mobility show four distinct microstructural pathways en route to 100% density: multiple dosed pores, hollow shells, hollow shells with a core, and multiple interconnected pores. The microstructures from our simulations are consistent with experimental observations in several different systems. Our results have important implications for rational synthesis of hollow nanostructures or aggregates with open pores, and for controlling the stability of nanoporous aggregates that are widely used for many applications.

Nanoporous alloy aggregates: synthesis and electrocatalytic activity

Nanoporous structures are widely used for many applications and hence there have been several efforts directed towards their synthesis. While several template-based and template-less approaches are available for monometallic systems, there is no general method for the synthesis of nanoporous multicomponent systems/alloys. We present a general template-less strategy for the synthesis of nanoporous alloy aggregates by controlled aggregation of nanoparticles in the solution phase with excellent control over morphology and composition as illustrated using AuPt, AuPd, PdPt and PtRu systems as examples. The Pt-based nanoporous clusters exhibit excellent activity for methanol oxidation with good long-term stability and CO tolerance. We show that the method can be extended to produce ternary catalysts and hence we expect our method to be widely used for the synthesis of multifunctional nanoporous structures for catalysis, sensor and drug-delivery applications.

Least path criterion (LPC) for unique indexing in a two-dimensional decagonal quasilattice

The least path criterion or least path length in the context of redundant basis vector systems is discussed and a mathematical proof is presented of the uniqueness of indices obtained by applying the least path criterion. Though the method has greater generality, this paper concentrates on the two-dimensional decagonal lattice. The order of redundancy is also discussed; this will help eventually to correlate with other redundant but desirable indexing sets.