Dielectric properties of humid mica surfaces

The dynamic behaviour of conduction and polarization processes on humid surfaces of mica has been studied in the frequency and time domains as function of the relative humidity, sample geometry, steady bias and electrode material. Detailed analysis of complex impedance and admittance plots has led to improved understanding of the role of the electrodes. The general conclusion which confirms and augments earlier studies is that humid mica surfaces may be represented by a parallel combination of an essentially extraneous electrode capacitance which does not depend on humidity and bias, and the surface processes which ultimately become dominated by low-frequency dispersion. It is concluded that the behaviour does not depend in a major way on the nature of the electrode material, which implies that the dispersive processes observed are intrinsic to the humid surface, and are not dominated by contact effects between the metal contacts and the humid surface.     

Dielectric properties of silver borophosphate glasses

Dynamic behaviour of electrical conduction and polarization in silver borophosphate glasses has been studied over wide range of frequencies and temperatures. The dielectric spectrum showed a strong dispersion in C() with rise in temperature which distinguishes the conduction process from a pure steady state. The observed behaviour was found to be temperature activated with an activation energy of 0.39 eV. The data have been analysed in terms of admittance plots and a model has been proposed on the basis of this analysis.     

Depolymerization of PET waste to potentially applicable aromatic amides: Their characterization and DFT study

Poly(ethylene terephthalate) waste has been depolymerized to a series of potentially applicable aromatic amides through aminolysis with different amines such as methylamine, ethylenediamine, ethanolamine, and butylamine at ambient conditions of temperature and pressure. The amides prepared were characterized by different techniques like Fourier transform infrared (FTIR), UV‐Visible spectroscopy, nuclear magnetic resonance (NMR), elemental analysis, mass spectrometry, powdered X‐ray diffraction (XRD), Raman spectroscopy, and thermal analysis. Further more, an attempt is being made to insight the physical parameters of the aromatic amides using ab initio DFT (Density Functional Theory) study. DFT calculations were performed at Becke's three parameter functional and Lee–Yang–Parr functional (B3LYP) level of calculation with 321‐G basis set. The atomic orbital energy (HOMO and LUMO) and energy gap is also represented. The vibrational frequencies optimized by DFT were in agreement with the experimental FTIR data. An efficient conversion of PET waste to amides was achieved without catalyst through environment friendly clean approach. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45153.     

User satisfaction and system success: an empirical exploration of user involvement in software development

For over four decades user involvement has been considered intuitively to lead to user satisfaction, which plays a pivotal role in successful outcome of a software project. The objective of this paper is to explore the notion of user satisfaction within the context of the user involvement and system success relationship. We have conducted a longitudinal case study of a software development project and collected qualitative data by means of interviews, observations and document analysis over a period of 3 years. The analysis of our case study data revealed that user satisfaction significantly contributes to the system success even when schedule and budget goals are not met. The case study data analysis also presented additional factors that contribute to the evolution of user satisfaction throughout the project. Users’ satisfaction with their involvement and the resulting system are mutually constituted while the level of user satisfaction evolves throughout the stages of software development process. Effective management strategies and user representation are essential elements of maintaining an acceptable level of user satisfaction throughout software development process.     

Generalized Maxwell-Wagner response in dispersive silver borophosphate glasses

The dielectric response of a glass-forming system (Ag₂OB₂O₃P₂O₅) has been measured in the frequency range from 10^–3–10⁵ Hz and over temperatures in the range 150–400 K for three different compositions. The dynamic behaviour of the conductance and capacitance in these glasses has been observed to follow fractional power-law dependencies on frequency which obey the generalized Maxwell-Wagner relationships. The power-law dispersions for the bulk and the surface layer of the non-ideal solid electrolyte 0.6Ag₂OxB₂O₃(0.4–x) P₂O₅ have been modelled mathematically using frequency-dependent resistive and capacitive elements in a conventional equivalent network. It is shown that controlled substitution of B₂O₃ in the glassy network influences the response and introduces an imperfect charge transport, the quasi-d.c. process of limited charge transport in place of bulk conduction, at higher frequencies, and affects the diffusion barrier at the electrodes to make them, weakly, more conductive at the lowest frequencies. The magnitudes of the activation energies of conduction indicate thermally activated localized hopping of silver ions between neighbouring sites in a structure that is modified by the addition of boron oxide.     

Electrical studies of leaves over wide frequency range

Dielectric properties of fresh leaves samples from different plant species were studied over the frequency range 10^-3 to 10⁴ Hz. The dynamic behaviour of the conductance and capacitance in leaf samples has been observed to follow fractional power law. The observed power-law dispersions have been modelled using frequency dependent resistive and capacitive elements of a conventional equivalent circuit     

Effective incorporation of TiO2 nanoparticles into polyamide thin‐film composite membranes

The effectiveness of TiO₂ nanoparticles in improving the performance of polyamide (PA) thin‐film composite (TFC) membranes has been investigated. PA TFC membranes were prepared by interfacial polymerization with m‐phenylenediamine (MPD) and 1,3,5‐benzene tricarbonyl trichloride (TMC) where TiO₂ particles were added during and after interfacial polymerization. To distribute the TiO₂ nanoparticles uniformly in the PA films, colloidally stable TiO₂ sols were synthesized and added to the aqueous MPD solution rather than to an organic TMC solution. Through the use of different incorporation methods, TiO₂ particles were located on the top surface, in PA film layer, and in both positions. In the case of dense PA layers, the hydrophilicity of the membranes was significantly improved due to the presence of TiO₂ particles, resulting in an increased water flux. On the other hand, the enhancement of water flux was less significant when TiO₂ particles were incorporated into a loose PA film that was prepared with additives. In addition, a BSA fouling test confirmed that TiO₂ nanoparticles effectively improve the antifouling properties of the membranes for both dense and loose PA films. This effect is possibly due to increased hydrophilicity, covering of the fouling space, and a reduction in surface roughness. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43383.     

Controlled release of aspirin from pH‐sensitive chitosan/poly(vinyl alcohol) hydrogel

The aim of this study was to develop a cheap, pH‐sensitive enteric coating of aspirin with biocompatible polymers. A novel approach was used to develop enteric coating from chitosan (CS) and poly(vinyl alcohol) (PVA). Solutions of CS and PVA (5 : 1 mol ratio) were mixed and selectively crosslinked with tetraethoxysilane. IR analysis confirmed the presence of the incorporated components and the existence of siloxane linkages between CS and PVA. The crosslinking percentage and thermal stability increased with increasing amount of crosslinker. The response of the developed coating in different media, such as water, pH (nonbuffer and buffer), and ionic media showed hydrogel properties. All hydrogels showed low swelling in acidic and basic pH media, whereas maximum swelling was exhibited at neutral pH. This pH sensitivity of the hydrogel has been exploited as enteric coating for commercial aspirin tablets. The dissolution test of enteric‐coated aspirin tablet in simulated gastric fluid (pH 1.2) showed 7.11% aspirin release over a period of 2 h, whereas a sustained release of remaining aspirin (83.25%) was observed in simulated intestinal fluid (pH 6.8). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Comparative pollen and foliar micromorphological studies using light microscopy and scanning electron microscopy of some selected species of Lamiaceae from Alpine Zone of Deosai Plateau,Western Himalayas

The study was conducted to highlight a detailed account of morphology of pollen chosen species of Lamiaceae through scanning electron microscopy, and the anatomical characteristics of leaf epidermis of seven species using simple light microscopy. In results, Anisomeles indica and Otostegia aucheri belong to subfamily Lamioideae because it has tricolpate pollen while the rest eight species belong to subfamily Nepetoideae (hexacolpate pollen). The exine sculpturing of pollen of studied species was found to be reticulate. In the family Lamiaceae, four kinds of stomata were found anomocytic, anisocytic, diacytic, and actinocytic, respectively. The cell wall patterns of epidermal cells were irregular or polygonal with straight or undulate walls. It was noted that the variety of the epidermal trichomes seems of taxonomically important for the identification of species of Lamiaceae. Both nonglandular and glandular trichomes were analyzed. The nonglandular trichomes were characterized with long, thin, and pointed apical unicellular cells. The nonglandular trichomes were A‐shaped in Thymus linearis. In Perovskia abrotanoides, stellate glandular trichomes were observed whereas in A. indica and Mentha royleana both glandular and nonglandular trichomes were found. In A. indica, the nonglandular trichomes were sessile and peltate in M. royleana. For the first time in this study, pollen and foliar micromorphological features of selected species of this area are carried out. These taxonomic characters were found to be important in discrimination of species from each other. In future, the detailed study with comprehensive morphology coupled with other important characters is required for delimitation of taxa at various levels.     

Pleurotus mushrooms. Part IB. Pathology, in vitro and in vivo growth requirements, and world status

Part IB of this review discusses growth abnormalities and diseases of the fruit bodies, as well as containments in the substrates that affect the quality and yield of the fruit bodies. The means and methods to overcome these problems during culturing of Pleurotus on commercial scales are described. In vitro growth requirements and prospects of producing mycelium on organic wastes in liquid culture are discussed. The effects of changes in the nutrients of growth substrate on the yield and quality of fruit bodies in vivo are brought out. Status of culturing Pleurotus in different parts of the world is evaluated. Finally, a critical consideration of the scope and problems of Pleurotus cultivation technology is given.