Ellagic acid - a novel organic electrode material for high capacity lithium ion batteries

Ellagic acid, a naturally occurring polyphenol, extracted from pomegranate husk, is found to be a very good organic electrode material for rechargeable lithium batteries with high reversible capacities of similar to 450 and 200 mA h g(-1) at C/10 and C/2.5 discharge rates, respectively; ex situ NMR studies reveal possible lithiation-delithiation modes at different stages of the charge-discharge process.

Ozone and carbon trioxide synthesis by low energy ion implantation onto solid carbon dioxide and implications to astrochemistry

Ion implantation experiments were carried out on amorphous (30 K) and crystalline (80 K) solid CO2 using both reactive (D+, H+) and non-reactive (He+) ions, simulating different irradiation environments on satellite and dust grain surfaces. Such ion irradiation synthesized several new species in the ice including ozone (O-3), carbon trioxide (CO3), and carbon monoxide (CO) the main dissociation product of carbon dioxide. The yield of these products was found to be strongly dependent upon the ion used for irradiation and the sample temperature. Ion implantation changes the chemical composition of the ice with recorded infrared spectra clearly showing the coexistence of D-3h and C-2v isomers of CO3, for the first time, in ion irradiated CO2 ice. (C) 2013 AIP Publishing LLC.

A model of coupled thermal, mechanical, and electrostatic field effects in III-N thin film heterostructures

A one-dimensional coupled multi-physics based model has been developed to accurately compute the effects of electrostatic, mechanical, and thermal field interactions on the electronic energy band structure in group III-nitrides thin film heterostructures. Earlier models reported in published literature assumes electro-mechanical field with uniform temperature thus neglecting self-heating. Also, the effects of diffused interface on the energy band structure were not studied. We include these effects in a self-consistent manner wherein the transport equation is introduced along with the electro-mechanical models, and the lattice structural variation as observed in experiments are introduced at the interface. Due to these effects, the electrostatic potential distribution in the heterostructure is altered. The electron and hole ground state energies decrease by 5% and 9%, respectively, at a relative temperature of 700 K, when compared with the results obtained from the previously reported electro-mechanical model assuming constant and uniform temperature distribution. A diffused interface decreases the ground state energy of electrons and holes by about 11% and 9%, respectively, at a relative temperature of 700 K when compared with the predictions based on uniform temperature based electro-mechanical model. (C) 2013 AIP Publishing LLC.

Li3MRuO5 (M = Co, Ni), new lithium-rich layered oxides related to LiCoO2: promising electrochemical performance for possible application as cathode materials in lithium ion batteries

We describe the synthesis and crystal structure of Li3MRuO5 (M = Co and Ni), new rock salt related oxides. Both the oxides crystallize in the layered LiCoO2 (alpha-NaFeO2) structure, as revealed by powder XRD data. Magnetic susceptibility data suggest that the oxidation states of transition metals are Li3Co3+(ls)Ru4+(ls) O-5 (ls = low spin) for the M = Co compound and Li3Ni2+Ru5+O5 for the M = Ni compound. Electrochemical investigations of lithium deintercalation-intercalation behaviour reveal that both Co and Ni phases exhibit attractive specific capacities of ca. 200 mA h g(-1) at an average voltage of 4 V that has been interpreted as due to the oxidation of Co3+ and Ru4+ in Li3CoRuO5 and Ni2+ to Ni4+ in the case of Li3NiRuO5. Thus, a different role of Ru ions is played in the isostructural oxides. Finally, in both cases evidence of irreversible behaviour above 4.2 V is observed and interpreted as formation of high valent ions or alternatively oxidation of oxide ions.

Structural, iono and thermoluminescence properties of heavy ion (100 MeV Si7+) bombarded Zn2SiO4:Sm3+ nanophosphor

Structural, iono (IL) and thermoluminescence (TL) studies of Zn2SiO4:Sm3+ (1-5 mol%) nanophosphor bombarded with swift heavy ions in the fluence range 3.91 x 10(12)-21.48 x 10(12) cm(-2) have been carried out. The average crystallite sizes for pristine and ion irradiated for 3.91 x 10(12) ions cm(-2) and 21.48 x 10(12) ions cm(-2) were found to be 34, 26 and 20 nm. With increase of ion fluence, the intensity of XRD peaks decreases and FWHM increases. The peak broadening indicates the stress induced point/clusters defects produced due to heavy ion irradiation. IL studies were carried out for different Sm3+ concentrations in Zn2SiO4 by irradiating with ion fluence of 15.62 x 10(12) ions cm(-2). The characteristic emission peaks at similar to 562, 599, 646 and 701 nm were recorded by exciting Si7+ ions in the fluence range 3.91 x 10(12)-21.48 x 10(12) ions cm(-2). These peaks were attributed to (4)G(5/2)-> H-6(5/2) (562 nm), (4)G(5/2)-> H-6(7/2) (599 nm), (4)G(5/2)-> H-6(9/2) (646 nm), and (4)G(5/2)-> H-6(5/2) (701 nm) transitions of Sm3+. The highest emission was recorded at 3 mol% of Sm3+ doped Zn2SiO4. TL studies were carried out for 3 mol% Sm3+ concentration in the fluence range 3.91 x 10(12)-21.48 x 10(12) ions cm(-2). Two U glow peaks at 152 and 223 degrees C were recorded. The kinetic parameters (E, b, and s), were estimated using Chen's peak shape method. Simple glow curve structure (223 degrees C), highly resistive, increase in TL. intensity up to 19.53 x 10(12) ions cm(-2), simple trap distribution makes Zn2SiO4:Sm3+ (3 mol%) phosphor highly useful in radiation dosimetry.

Naphthalene Carbohydrazone Based Dizinc(II) Chemosensor for a Pyrophosphate Ion and Its DNA Assessment Application in Polymerase Chain Reaction Products

A new naphthalene carbohydrazone based dizinc(II) complex has been synthesized and investigated to act as a highly selective fluorescence and visual sensor for a pyrophosphate ion with a quite low detection limit of 155 ppb; this has also been used to detect the pyrophosphate ion released from polymerase-chain-reaction.

Platinum Ion-Doped TiO2: High Catalytic Activity of Pt2+ with Oxide Ion Vacancy in Ti1-x4+Ptx2+O2-x Compared to Pt4+ without Oxide Ion Vacancy in Ti1-x4+Ptx4+O2

Ti0.97Pt0.032+O1.97 and Ti0.97Pt0.034+O2 have been synthesized by a solution combustion method using alanine and glycine as the fuels, respectively. Both crystallize in anatase TiO2 structure with 15 nm average crystallite size. X-ray photoelectron spectroscopy (XPS) confirmed Pt ions are in the 2+ state in Ti0.97Pt0.03O1.97 (alanine) and 4+ state in Ti0.97Pt0.03O2 (glycine). The rate of CO oxidation occurring over Ti0.97Pt0.032+O1.97 (0.76 mu mol.g(-1).s(-1)) is similar to 10, times more than that over Ti0.97Pt0.034+O2 at 60 degrees C (0.08 mu mol.g(-1).s(-1)). A large shift in 100% hydrocarbons conversion to lower temperature was observed for Pt2+ ion-substituted TiO2 relative 10 that for Pt4+ ion-substituted TiO2. After reoxidation of the reduced compound by H-2 as well as CO, Pt ions are stabilized in mixed valences, 2+ and 4+ states. The role of oxide ion vacancy has been demonstrated by CO oxidation and H-2 + O-2 recombination reactions in the presence and absence of O-2. We analyze the activated lattice oxygens upon substitution of Pt2+ and Pt4+ ions in TiO2, using first-principles density functional theory (DFT) calculations with supercells of Ti31Pt1O63, Ti30Pt2O62, and Ti29Pt3O61 for Pt2+ ion substitution and Ti31Pt1O64, Ti30Pt2O62, and Ti29Pt3O61 for Pt4+ ion substitution in TiO2. We find that the local structure of Pt2+ ion has a distorted square planar geometry and that of Pt4+ ion has an octahedral geometry similar to that of Ti4+ ion in pure TiO2. The change in coordination of Pt2+ ion gives rise to weakly bonded oxygens, and these oxygens are involved in high rates of catalytic reaction. Thus, the high catalytic activity results from synergistic roles of Pt2+ ion and oxide ion vacancy and weakly bonded lattice oxygen.

Employing synergistic interactions between few-layer WS2 and reduced graphene oxide to improve lithium storage, cyclability and rate capability of Li-ion batteries

The aim of the contribution is to introduce a high performance anode alternative to graphite for lithium-ion batteries (LiBs). A simple process was employed to synthesize uniform graphene-like few-layer tungsten sulfide (WS2) supported on reduced graphene oxide (RGO) through a hydrothermal synthesis route. The WS2-RGO (80:20 and 70:30) composites exhibited good enhanced electrochemical performance and excellent rate capability performance when used as anode materials for lithium-ion batteries. The specific capacity of the WS2-RGO composite delivered a capacity of 400-450 mAh g(-1) after 50 cycles when cycled at a current density of 100 mA g(-1). At 4000 mA g(-1), the composites showed a stable capacity of approximately 180-240 mAh g(-1), respectively. The noteworthy electrochemical performance of the composite is not additive, rather it is synergistic in the sense that the electrochemical performance is much superior compared to both WS2 and RGO. As the observed lithiation/delithiation for WS2-RGO is at a voltage 1.0 V (approximate to 0.1 V for graphite, Li* /Li), the lithium-ion battery with WS2-RGO is expected to possess high interface stability, safety and management of electrical energy is expected to be more efficient and economic. (C) 2013 Elsevier Ltd. All rights reserved.

Polymer template-assisted microemulsion synthesis of large surface area, porous Li2MnO3 and its characterization as a positive electrode material of Li-ion cells

Lithium-rich manganese oxide (Li2MnO3) is prepared by reverse microemulsion method employing Pluronic acid (P123) as a soft template and studied as a positive electrode material. The as-prepared sample possesses good crystalline structure with a broadly distributed mesoporosity but low surface area. As expected, cyclic voltammetry and charge-discharge data indicate poor electrochemical activity. However, the sample gains surface area with narrowly distributed mesoporosity and also electrochemical activity after treating in 4 M H2SO4. A discharge capacity of about 160 mAh g(-1) is obtained. When the acid-treated sample is heated at 300 A degrees C, the resulting porous sample with a large surface area and dual porosity provides a discharge capacity of 240 mAh g(-1). The rate capability study suggests that the sample provides about 150 mAh g(-1) at a specific discharge current of 1.25 A g(-1). Although the cycling stability is poor, the high rate capability is attributed to porous nature of the material.

Ternary ion-pair complexation: a protocol for chiral discrimination and the assignment of absolute configuration of chiral hydroxy acids

The study demonstrates the utility of ternary ion-pair complex formed among BINOL (1,1'-Bi-2-naphthol), a carboxylic acid and an organic base, such as, dimethylpyridine (DMAP), 1,4-diazabicyclo2.2.2]octane (DABCO), as a versatile chiral solvating agent (CSA) for the enantiodiscrimination of carboxylic acids, measurement of enantiomeric excess (ee) and the assignment of absolute configuration of hydroxy acids. The proposed mechanism of ternary complex has wider application for testing the enantiopurity owing to the fact that the binary mixture using BINOL alone does not serve as a solvating agent for their discrimination. In addition, the developed protocol has an excellent utility for the assignment of the absolute configurations of hydroxy acids.

Stereoselective geminal difunctionalization of vinyl arenes mediated by the bromonium ion

An anti-Markovnikov geminal oxyamination of styrenyl alkenes in an intermolecular fashion using the umpolung strategy mediated by the bromonium ion is reported. Isotope labeling studies confirm the migration of the phenyl group in the semipinacol rearrangement.

Inhibition of cancer cell proliferation and apoptosis-inducing activity of fungal taxol and its precursor baccatin III purified from endophytic Fusarium solani

Background: Taxol (generic name paclitaxel), a plant-derived antineoplastic agent, used widely against breast, ovarian and lung cancer, was originally isolated from the bark of the Pacific yew, Taxus brevifolia. The limited supply of the drug has prompted efforts to find alternative sources, such as chemical synthesis, tissue and cell cultures of the Taxus species both of which are expensive and yield low levels. Fermentation processes with microorganisms would be the methods of choice to lower the costs and increase yields. Previously we have reported that F. solani isolated from T. celebica produced taxol and its precursor baccatin III in liquid grown cultures J Biosci 33: 259-67, 2008. This study was performed to evaluate the inhibition of proliferation and induction of apoptosis of cancer cell lines by the fungal taxol and fungal baccatin III of F. solani isolated from T. celebica. Methods: Cell lines such as HeLa, HepG2, Jurkat, Ovcar3 and T47D were cultured individually and treated with fungal taxol, baccatin III with or without caspase inhibitors according to experimental requirements. Their efficacy on apoptotic induction was examined. Results: Both fungal taxol and baccatin III inhibited cell proliferation of a number of cancer cell lines with IC50 ranging from 0.005 to 0.2 mu M for fungal taxol and 2 to 5 mu M for fungal baccatin III. They also induced apoptosis in JR4-Jurkat cells with a possible involvement of anti-apoptotic Bcl2 and loss in mitochondrial membrane potential, and was unaffected by inhibitors of caspase-9,-2 or -3 but was prevented in presence of caspase-10 inhibitor. DNA fragmentation was also observed in cells treated with fungal taxol and baccatin III. Conclusions: The cytotoxic activity exhibited by fungal taxol and baccatin III involves the same mechanism, dependent on caspase-10 and membrane potential loss of mitochondria, with taxol having far greater cytotoxic potential.

Role of dicarboxylate linkers in Mn-III-salicylaldoximate based extended structures: synthesis, structures, and magnetic behavior

Four new oxo-centered Mn-III-salicylaldoximate triangle-based extended complexes (Mn6O2)-O-III(salox)(6)(EtOH)(4)(phda)](n)(saloxH(2))(n)(2H(2)O)(n) (1), (Mn6O2)-O-III(salox)(6)(MeOH)(5)(5-I-isoph)](n)(3MeOH)(n) (2), (Mn6O2)-O-III(salox)(6)(MeOH)(4)(H2O) (5-N-3-isoph)](n)(4MeOH)(n) (3) and (Mn3NaO)-Na-III(salox)(3)(MeOH)(4)(5-NO2-isoph)](n)(MeOH)(n) (H2O)(n) (4) salox=salicylaldoximate, phda=1,3-phenylenediacetate, isoph=isophthalate] have been synthesized under similar reaction conditions. Single crystal X-ray structures show that in 1, only one type of Mn-6 cluster is arranged in 1D, whereas in 2 and 3 there are two types of clusters, differing in the way the triangle units are joined and assembled. In complex4, however, the basic building structure is heteronuclear and based on Mn-3 units extended in 2D. Susceptibility measurements (dc and ac) over a wide range of temperatures and fields show that the complexes1, 2, and 3 behave as single molecule magnets (SMMs) with S=4ground state, while 4 is dominantly antiferromagnetic with a ground spin state S=2. Density functional theory calculations have been performed on model complexes to provide a qualitative theoretical interpretation for their overall magnetic behavior.

Morphology and electrochemical performance of graphene nanosheet array for Li-ion thin film battery

Highly branched and porous graphene nanosheet synthesized over different substrates as anode for Lithium ion thin film battery. These films synthesized by microwave plasma enhanced chemical vapor deposition at temperature 700 degrees C. Scanning electron microscopy and X-ray photo electron spectroscopy are used to characterize the film surface. It is found that the graphene sheets possess a curled and flower like morphology. Electrochemical performances were evaluated in swezelock type cells versus metallic lithium. A reversible capacity of 520 mAh/g, 450 mAh/g and 637 mAh/g was obtained after 50 cycles when current rate at 23 mu A cm(2) for CuGNS, NiGNS and PtGNS electrodes, respectively. Electrochemical properties of thin film anode were measured at different current rate and gave better cycle life and rate capability. These results indicate that the prepared high quality graphene sheets possess excellent electrochemical performances for lithium storage. (C) 2013 Elsevier Ltd. All rights reserved.

Computationally Efficient and Accurate Modeling of Li-ion Battery

A computationally efficient Li-ion battery model has been proposed in this paper. The battery model utilizes the features of both analytical and electrical circuit modeling techniques. The model is simple as it does not involve a look-up table technique and fast as it does not include a polynomial function during computation. The internal voltage of the battery is modeled as a linear function of the state-of-charge of the battery. The internal resistance is experimentally determined and the optimal value of resistance is considered for modeling. Experimental and simulated data are compared to validate the accuracy of the model.