Electrical conductive properties of some composites of gum arabic biopolymer and magnetite nanoparticles

DC electrical conductive properties of some composites of gum arabic biopolymer (host) and magnetite nanoparticles (guest) synthesized in different weight percentages have been studied as a function of temperature and applied bias voltage to explore the effect of the guest on the electrical conduction of the host. Two types of trap distributions (single discrete and exponential) have been found in these composites. The observed results show that the conductivity of the composites increases with increasing guest content along with a decrease in activation energy. Percolation theory has been employed for the analysis of the room temperature electrical conductivity enhancement with the variation of guest content. The activation energy and the pre-exponential factor values estimated following Arrhenius relation satisfies the compensation law

Thermal decomposition of a molecular material {N(n-C4H9)4[FeIIFeIII(C2O4)3]}∞ leading to ferrite: A reaction kinetics study

A multi-step thermal decomposition of a molecular precursor, {N(n-C4H9)4[FeIIFeIII(C2O4)3}∞ has been studied using non-isothermal thermogravimetry (TG) measurements in the temperature range 300 to ~800 K at multiple heating rates (5, 10 and 20 K min-1). The thermal decomposition of the oxalate-based complex proceeds stepwise through a series of intermediate reactions. Two different isoconversional methods, namely, improved iterative method and model-free method are employed to evaluate the kinetic parameters: activation energy and rate of reaction, and the most probable reaction mechanism of thermal decomposition is also determined. The different reaction pathways leading to different steps in the TG profile have also been explored which are supplemented by earlier experimental observations of the present authors

High dilutions of two drugs induce changes in crystal water structure of lactose as revealed by thermogravimetry and differential scanning calorimetry

Ultra-high dilutions (UHD) of drugs used in homeopathy are preserved in sugars. How do solid sugars assimilate characteristics of UHDs? This study attempts to answer this question. The three UHDs of Acid fluoric, Acid nitric, and ethanol were mixed with lactose at 1 µL/g and analyzed by thermogravimetry (TG) and differential scanning calorimetry (DSC) to see any change in their crystal water. TG results show a mass loss of 4.9% at 146.8C for Acid fluoric 30 cH, of 7.1% at 146.6C for Acid nitric 30 cH, and5.1% at 146.5C for ethanol. DSC results show that the change in enthalpy for Acid fluoric 30 cH is 157.3 J/g at 153.8C, that for Acid nit 30 cH is 122.8 J/g at 148.3C, and that for ethanol is 154.9 J/g at 156.3C. Bound water in lactose crystals and corresponding enthalpies vary markedly in the three drugs tested. This indicates that the number of hydrogen bonds and their bond strength vary inbound water of medicated lactose crystals

An Early Assessment of Medium Range Monsoon Precipitation Forecasts from the Latest High-Resolution NCEP-GFS (T1534) Model over South Asia

Reliable prediction of the South Asian monsoon rainfall and its variability is crucial for various hydrological applications and early warning systems. The National Centers for Environmental Prediction – Global Forecast System (NCEP–GFS) is one of the popular global deterministic numerical weather prediction models, which is recently upgraded from T574 to T1534. In this paper, medium range monsoon precipitation forecasts from both the T1534 and T574 models are critically evaluated over the South Asia for the peak monsoon months (July and August) of 2015. Although both the versions of GFS model show similar large-scale monsoon rainfall patterns, the dry bias over the northwest India and equatorial Indian Ocean is noticeably improved in day-1 through day-5 forecasts in the new high-resolution T1534 model. The error decomposition analysis shows similar error characteristics in the monsoon rainfall prediction from both the versions of GFS model, in general. However, forecast improvement factor shows 10-30% improvement in precipitation forecast from the latest T1534 model over most parts of the South Asia. These preliminary analyses suggest that a suitable bias-correction to the GFS model precipitation forecasts will be useful for any specific application

Synthesis, Characterization, and Magnetic Properties of Iron(II) Complex with 2,6-Bis(pyrazol-3-yl)pyridine Ligand and Tetracyanonickelate Anion

The complex containing iron(II), 2,6-bis(pyrazol-3-yl)pyridine (3-bpp) as ligand, and tetracyanonickelate as counter anion has been synthesized and characterized. The characterization data suggest the corresponding formula of [Fe(3-bpp)2][Ni(CN)4]·4H2O. Meanwhile, the SEM–EDX analysis image confirms the existence of all elements contained in the complex except the hydrogen atom. The infrared spectra exhibit vibration bands of the functional groups of 3-bpp ligand and [Ni(CN)4]−1 anion. From magnetic property measurement, the complex's molar magnetic susceptibility (XMT) value is 2.65 emu mol−1 K at 300 K, which contains about 75% high-spin state of the Fe(II) complex. Upon lowering the temperature, the XMT value gradually decreases around 1.37 emu mol−1 K at 13 K. It decreases sharply to about 0.73 emu mol−1 K at 2 K. These values reveal that Fe(II) complex is in the low-spin (LS) state. As a result, the complex exhibited spin-crossover characteristics of gradual transition without thermal hysteresis, and the transition temperature occurred below room temperature with a transition temperature (T1/2) close to 140 K. The spin crossover property of the complex is supported by a thermochromic reversible color change from red-brown at room temperature to dark brown on cooling in liquid nitrogen associated with the high-spin to low-spin transition

A mathematical account of marine corrosion behaviour of galvanised steel structures installed in Digha coast of Bay of Bengal

280-281An approximate mathematical equation in terms of atmospheric chloride count, C(mg/m(2)/day) and the average rainfall, R(f)(mm/day) to evaluate marine corrosion rate of galvanised structures and installations is attempted. Mathematical relationship giving thickness-loss, TL, due to marine corrosion of galvanised steel installations at the Digha coast of the Bay of Bengal has been worked out to be TL = 1.086 x 10(-2) x C x R(f)

Structural, morphological and optical characterization of green synthesized ZnS nanoparticles using Azadirachta Indica (Neem) leaf extract

ZnS nanoparticles have been synthesized using various amounts of aqueous Azadirachta Indica (Neem) leaf extract as capping agent and stabilizer. The synthesized nanoparticles were studied by FTIR, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive analysis of X-rays (EDAX) and UV-Visible spectroscopy. FTIR spectra shows that the biomolecules such as polyphenols, carboxylic acids, polysaccharide, amino acids and proteins present in the extract are responsible for the binding and stabilizing the synthesized ZnS nanoparticles. Analysis of the XRD data confirms the cubic structure of the synthesized materials with an average particle size of ~2 nm. Using XRD data the microstrain and dislocation density in ZnS crystals have been estimated. The particle size, strain and dislocation density are found to be affected by the amount of the extract used for synthesis. SEM and TEM studies were made to study the morphology and size of the particles. The EDAX spectra confirmed the presence of zinc and sulfur in single nanoparticle. UV-Visible spectra indicated a blue shift in the absorption peak for the extract-capped ZnS materials in comparison to the pure ZnS. The particle size of the ZnS nanoparticles estimated using UV-Visible spectral data along with those obtained from XRD analysis confirms that the green-synthesized ZnS nanoparticles lie in the range of quantum dots. The present study describes a simple, cost effective way of nanoparticle synthesis suitable for large scale productio