Effect of Space Charge on Polarization Reversal Currents in a Vinylidene Fluoride/Trifluoroethylene Copolymer

Polyvinylidene fluoride and its copolymers with trifluoroethylene and tetrafluoroethylene are ferroelectric. Reversal of polarization in these polymers is known to occur by a rotation of the polar molecular chains, in response to an externally applied electric field. Recent evidence suggests that the dynamics of polarization reversal can be affected by movement of space charges in the amorphous phase of the polymers. If a 75/25 mol.% vinylidene fluoride/trifluoro-ethylene (VF₂/VF₃) copolymer is poled at elevated temperature, the subsequent polarization reversal currents show large asymmetry and significant shifts in successive reversals. The field required to reverse the polarization in such high-temperature poled material is significantly larger than the normal coercive field. The asymmetry in the reversal currents is consistent with the presence of local fields within the polymer, generated by space charge which accumulates during the poling process. The subsequent movement of this space charge causes the shift in successive reversal currents. The variation of reversal current with temperature indicates that the movement of space charge within the copolymer is a thermally activated process.     

Pressure effects in multiphase binary diffusion couples

A systematic study has been carried out of the effect of pressure upon growth kinetics of intermediate phases formed in diffusion couples in the binary systems Ni-Al, U-A1, and U-Cu. Even though applied pressures greater than 100 MPa and long times were investigated little or no pressure effect was observed, in disagreement with previous literature reports. The magnitude of observed pressure effects falls within that expected by closure of Kirkendall porosity.     

Synthesis of nano polyaniline and poly-<Emphasis Type="Italic">o</Emphasis>-anisidine and applications in alkyd paint formulation to enhance the corrosion resistivity of mild steel

Protection of oxidizable metals against corrosion has now being intensively investigated, by applying or developing different methods such as coatings and conversion films; however, all reported methods involve environmentally hazardous materials. Conducting polymers have now been used as corrosion inhibitor coatings that are either chemically or electrochemically deposited on the metal substrate. The application of nanotechnology in the corrosion protection of metals has recently gained momentum. Environmental impact can also be improved by utilizing nanostructure particulates in coatings and eliminating the requirement of toxic solvents. We report here the synthesis of nanoparticles of polyaniline (PANI) and poly-o-anisidine (POA) using emulsion polymerization method in micellar solution of SDS and their anticorrosive property has been experimentally checked. The prepared nanoparticles have been characterized by FTIR and TEM. The nanoparticles of the synthesized polymers were dispersed in alkyd paint formulation for coatings on the metal surface (mild steel). The water absorption in the prepared coatings was also studied. The corrosion rate of polymeric film was determined by weight loss measurement and the surface morphology was examined by SEM. The nano PANI/Alkyd coatings showed considerable protection against corrosion than the POA/alkyd coatings.     

Relative performance of chelated zinc and zinc sulphate for lowland rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

Field experiments were conducted during the wet seasons of 2005–2006 and 2006–2007 on an Aeric Endoaquept (pH 7.2) to study the relative performance of chelated zinc [Zn ethylene diamine tetra-acetic acid (EDTA)] and zinc sulphate (ZnSO₄) on the growth and yield of rice (cv. IET 4094). The diethylene triamine penta-acetic acid (DTPA) extractable (available) Zn concentration in soil and total Zn content in dry matter of rice increased initially up to 28 days of crop growth when Zn was applied as a single basal source, being greater with chelated Zn compared with ZnSO₄ application. The highest mean Zn uptake by rice grain and straw was found to be 209.2 and 133.8 g ha⁻¹, respectively, in the treatment T₇ (1 kg Zn ha⁻¹ as Zn-EDTA at basal). The mean filled grain percentage, thousand grain weight and number of panicles m⁻² were highest with 90.4%, 25.4 g and 452, respectively, in treatment T₇ where 1 kg ha⁻¹ Zn as Zn-EDTA was applied. The highest yield of grain and straw was 5.5 and 7.3 t ha⁻¹, respectively, in treatment T₇, resulting in a 37.5 and 43.1% increase in yield over that of the control during both the years.     

Lactic Fermentations of Dairy Foods and Their Biological Significance

Fermentation is one of the methods of food preservation. Over years this method has evolved into a sophisticated art. Milk can be fermented by bacteria, yeasts, and molds to produce a variety of products such as yogurt, cheeses, sour cream, and buttermilk. Modification of milk by microorganisms affects both the physicochemical properties and the economic value of milk. The physicochemical changes are manifested in such properties as flavor, texture, and nutritive value. The economic value of milk is enhanced by the increased storage life of the products. A majority of these modifications are by the enzymes origination from microorganisms and acting on the protein, lipids, and carbohydrates in milk. the products resulting from such changes introduce variety into human diets.changes induced in milk constituents by microorganisms are discussed with regard to flavor, texture, and nutritive value. The significance of such modifications also is considered in terms of microbial synthesis of vitamins, natural antibiotics, natural anticarcinogenic substances, and enzymes. Although the mechanisms of these modifications are not yet understood, studies under in vitro conditions to delineate the physiological implications and nutritional and therapeutic significance of such modifications are described.     

Evaluation of Drug Layering and Coating: Effect of Process Mode and Binder Level

Top-spray layering and Wurster coating are common techniques for layering and coating operations, respectively. In the present study, the efficiency of these techniques was compared with rotolayering and rotocoating in the Niro-Aeromatic MP-1 Rotoprocessor. Also, three different polymers were evaluated as binding agents in the layering procedure. A solution containing drug and a suitable binder was layered onto nonpareil seeds followed by coating with a water-insoluble polymer. The pellets were evaluated for physical properties, surface characteristics and drug content (assay). The process efficiency was evaluated from process time, assay, and SEM data of the pellets. Efficiency of layering was compared between toplayering and rotolayering processes while efficiency of coating was compared between Wurster coating and rotocoating processes. The physical properties of pellets were used to explain the influence of binder nature and level of use in the layering process.