Structural, impedance, dielectric and modulus analysis of LiNi1-x-y-0.02Mg0.02CoxZnyO2 cathode materials for lithium-ion batteries

Mg, Co and Zn co-substituted layer-structured cathode materials LiNiCoxZnyMg0.02O2 (x = y = 0.0, 0.02 and 0.04) were prepared by a solid-state reaction method. The materials were systematically characterized by X-ray diffraction (XRD), field effect scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FT-IR), and electrical impedance spectroscopy (EIS) techniques. XRD analyses revealed the formation of a rhombohedral structure in the prepared materials with a typical α-NaFeO2 layered structure within R3¯m space group. The grain size was determined by FESEM in the range from 3.19 to 3.85 μm for all materials synthesized. The site of the local cation (Li–O) and of the transition metal cations (M–O) in the materials were identified by FT-IR. The complex impedance and modulus studies suggested the presence of a non-Debye type of multiple relaxations in these materials. The dielectric constant was found to increase with increasing Co and Zn concentrations. The ac conductivity studies revealed a typical negative temperature coefficient of resistance (NTCR) behavior, and the conductivity values varied from 1.58 × 10−5 to 8.46 × 10−6 S cm−1. The activation energy determined from the Arrhenius plots at 50 Hz was in the range of 0.23–0.78 eV

Role of glutathione S-transferases in oxidative stress-induced male germ cell apoptosis

Cellular apoptosis in a tissue may occur for the maintenance of proper ratio of cells or because of toxic effects of free radicals or other agents. Male germ cell apoptosis is pivotal in maintaining the proper functioning of the testis, but it is not clear how free radicals affect germ cells and what the defense mechanisms are that are used by these cells to combat the toxic effects of the products of oxidative stress. This study shows that male germ cells are susceptible to H2O2-induced stress and, upon exposure to H2O2 in vitro, demonstrate a typical apoptotic phenotype that includes DNA fragmentation and formation of DNA ladders. Other changes include considerable accumulation of products of lipid peroxidation in the germ cells after exposure to H2O2. Evidence is presented for the existence of multiple isoforms of glutathione S-transferases (GSTs) that possess both transferase and Se-independent peroxidase activity. Germ cell GST activity increases after H2O2 exposure. If this increase in activity is inhibited with suitable inhibitors, the formation of products of lipid peroxidation is augmented, resulting in germ cell apoptosis. Also, when constitutive GST activity is inhibited, accumulation of products of lipid peroxidation occurs, resulting in increased cellular apoptosis. These data show that GSTs form a part of adaptive response of germ cells to oxidative stress and are important constituents in detoxifying the products of lipid peroxidation

N-acetylcysteine prevents MAA induced male germ cell apoptosis: role of glutathione and cytochrome c

Exposure to methoxyacetic acid (MAA), a major byproduct of the paint industry, causes testicular atrophy in multiple species. This study demonstrates DNA breakdown in rat germ cells after exposure to MAA in vivo within 12 h, leading to 40% germ cell death by 24 h. Within 4 h of treatment, cytochrome c is released from the mitochondria into the cytosol without the involvement of mitochondrial potential loss, reactive oxygen species generation or lipid peroxidation events. Peak activation of caspase-9 and caspase-3 is detectable post treatment at 4 and 8 h respectively. There is a decrease in germ cell glutathione levels within 2 h of MAA treatment. Replenishment of glutathione by pretreatment of the animals with the antioxidant N-acetylcysteine prior to MAA treatment could prevent the release of cytochrome c, DNA fragmentation and cell death

Novel Behavior of Gd 3+ Ion in La 2 Al 2 Gd 2 O 9 Phosphor Prepared via Solid State Reaction Method

Abstract

Structural, morphological, impedance and magnetic studies of nanostructured LiNi0.45M0.1Mn0.45O2 (MCu and Al) cathode materials for lithium-ion batteries

Layered structure LiNi0.45M0.1Mn0.45O2 (MCu and Al) cathode materials for lithium-ion batteries are synthesized by solâgel auto combustion method. The structural, morphological, electrical and magnetic properties are examined by X-ray diffraction (XRD), field effect scanning electron microscope FESEM, FT-IR, EIS and ESR. XRD data revealed the rhombohedral and α-NaFeO2 structure with a space group R-3m. The electrical conductivity, dielectric constant, and dielectric loss are measured in the room temperature at a frequency ranging from 20 Hz to 1 MHz. The electrical conductivity of the compound is measured by AC impedance. An effective improvement in the electrical conductivity of order 5.42 Ã 10â6 S/cm is observed for the copper doped LNMO compounds. ESR spectra is recorded at room temperature on a Bruker EMX model X-band spectrometer operating at a frequency of 9.50 GHz. The critical dopants of Cu, with minimum g-factor and maximum line-width (W) are observed. Keywords: Solâgel, FESEM, AC impedance, ES

Intraseasonal oscillation (ISO) in the MLT zonal wind over Kolhapur (16.8° N) and Tirunelveli (8.7° N)

Simultaneous observations of the mean zonal winds at 88 km obtained by the medium-frequency (MF) radars at Kolhapur (16.8° N, 74.2° E) and Tirunelveli (8.7° N, 77.8° E) have been used to study the intraseasonal oscillation (ISO) in the MLT region. The influences of the intraseasonal variations in the lower tropospheric convective activity associated with the Madden-Julian oscillations on the latitudinal behavior of intraseasonal oscillations (ISO) of the zonal winds in the equatorial mesosphere and lower thermosphere (MLT) have been studied. The ISO activity in the lower tropospheric convective activity is examined by employing outgoing long wave radiation (OLR) as a proxy for deep convective activity occurring in the tropical lower atmosphere. The ISO activity in the zonal wind over TIR is more correlated with that in the convective activity\ud compared to the ISO over KOL. The latitudinal and temporal variabilities of the ISO in MLT zonal winds are explained in terms of the intraseasonal variabilities in the convective activity