Metronidazole-loaded nanostructured lipid carriers to improve skin deposition and retention in the treatment of rosacea

The objective of the present investigation was to improve the skin deposition and retention of metronidazole (MTZ) in rosacea therapy by incorporating it into nanostructured lipid carriers (NLCs). The main challenge in this endeavor was the partial hydrophilicity of MTZ, which mandated careful selection of excipients, including solid and liquid lipids, surfactants, and their ratios in combination. NLCs were produced by the phase inversion temperature method and finally converted into a gel for topical application. The prepared nanoparticles were evaluated for their particle size, zeta potential, entrapment efficiency, solid-state characteristics, surface morphology, in vitro drug release, and permeation through excised skin. The gel was additionally characterized for its pH, drug content, viscosity, and spreadability. The prepared nanoparticles were spherical in shape and of size less than 300?nm. Incorporation of judiciously chosen excipients made possible a relatively high entrapment efficiency of almost 40%. The drug release was found to be biphasic, with an initial burst release followed by sustained release up to 8?hours. In comparison to the plain drug gel, which had a tissue deposition of 11.23%, the NLC gel showed a much superior and desirable deposition of 26.41%. The lipophilic nature of the carrier, its size, and property of occlusion enabled greater amounts of drug to enter and be retained in the skin, simultaneously minimizing permeation through the skin, i.e. systemic exposure. The results of the study suggest that NLCs of anti-rosacea drugs have the potential to be used in the therapy of rosacea.     

Estimation of vapour pressure and partial pressure of subliming compounds by low-pressure thermogravimetry

A method for the estimation of vapour pressure and partial pressure of subliming compounds under reduced pressure, using rising temperature thermogravimetry, is described in this paper. The method is based on our recently developed procedure to estimate the vapour pressure from ambient pressure thermogravimetric data using Langmuir equation. Using benzoic acid as the calibration standard, vapour pressure-temperature curves are calculated at 80, 160 and 1000 mbar for salicylic acid and vanadyl bis-2,4-pentanedionate, a precursor used for chemical vapour deposition of vanadium oxides. Using a modification of the Langmuir equation, the partial pressure of these materials at different total pressures is also determined as a function of temperature. Such data can be useful for the deposition of multi-metal oxide thin films or doped thin films by chemical vapour deposition (CVD).     

Temperature‐dependent pyrolytic product evolution profile for polypropylene

The composition of the pyrolysis products of plastics depends on disintegration of the macromolecule into variety of hydrocarbon fractions. In this work, a detailed gas chromatographic study of pyrolysis products of polypropylene (PP) between 200 and 600°C was carried out. The pyrograms have been analyzed in terms of amount of different products evolved at various pyrolysis temperatures. At low pyrolysis temperatures (200–300°C), the yield of lighter hydrocarbons (C5‐C10) is low; it gradually increases until maximum decomposition temperature (446°C) and decreases thereafter. The following reaction types were considered to explain the decomposition mechanism of PP: (a) main chain cleavage to form chain‐ terminus radicals; (b) intramolecular hydrogen transfer to generate internal radicals; (c) intermolecular hydrogen transfer to form both volatile products and radicals; and (d) β‐scission to form both volatiles and terminally unsaturated polymer chains. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Self nanoemulsifying granules (SNEGs) of meloxicam: preparation,characterization, molecular modeling and evaluation of in vivo anti-inflammatory activity

Meloxicam, a BCS class II drug belonging to the class of NSAIDs is indicated in conditions of rheumatoid arthritis, ankylosing spondylitis and osteoarthritis in which rapid onset of drug action is desired to reduce inflammation and pain. The objective of the study was to thus develop Self Nanoemulsifying Granules (SNEGs) of Meloxicam (MLX) for enhancement of solubility; and subsequently dissolution rate, thus aiming for a faster onset of action. Preliminary studies along with molecular modeling studies were carried out for selection of appropriate lipids, surfactants and cosurfactants for the development of MLX-loaded Self Nanoemulsifying preconcentrate (SNEP). A charge inducer was incorporated into the formulation so as to increase the solubility of MLX in lipids and hence, drug loading. A three-factor D-optimal mixture design was used for optimization of MLX loaded SNEP. The role of charge inducer in increasing the drug loading of MLX in SNEDDS was studied by molecular dynamics simulation using Desmond. Optimized SNEP was adsorbed onto solid carriers to form SNEGs for improved stability and enhanced flow properties. Physical characterization studies of SNEGs, in vitro release studies, and in vivo evaluation of anti-inflammatory activity of the optimized formulation were performed. All the results indicated that MLX SNEGs can be a promising alternative to conventional oral NSAIDs therapy because of enhanced dissolution characteristics and subsequent rapid onset of action.     

Robust analysis for improvement of vowel onset point detection under noisy conditions

Vowel onset point (VOP) is the instant of time at which the vowel region starts in a speech signal. The VOPs are used as anchor points to design various speech based systems. Different algorithms exist in the literature to identify the occurrences of vowels in continuous spoken utterances. The algorithm based on combined evidences derived from source excitation, spectral peaks and modulation spectrum have been used as a baseline system for the present study. The baseline system provides a satisfactory level of performance under clean data condition. However under noisy data condition the performance of the previous system may be improved further by additional pre-processing of the raw speech data and post-processing the detected VOPs. In this paper we propose to use the speech enhancement techniques as pre-processing module to remove the noise from the speech data under different noisy conditions. The pre-processed speech data is then passed through the baseline system to detect the VOPs. It has been observed that there exist several spurious VOPs at the output of the baseline system. We propose to use a post-processing module based on average signal-to-noise ratio and information derived from the glottal closure instant to remove the spurious VOPs. The experiments were carried out on clean, artificially injected noisy, and data collected from the practical noisy environments. The results suggest that the proposed system using pre-processing and post-processing modules is robust and shows an improvement of 28–35 % over the existing baseline system by removing the spurious VOPs under different noisy conditions.     

Thermoelectric Properties of Polymeric Mixed Conductors

The thermoelectric (TE) phenomena are intensively explored by the scientific community due to the rather inefficient way energy resources are used with a large fraction of energy wasted in the form of heat. Among various materials, mixed ion‐electron conductors (MIEC) are recently being explored as potential thermoelectrics, primarily due to their low thermal conductivity. The combination of electronic and ionic charge carriers in those inorganic or organic materials leads to complex evolution of the thermovoltage (V_oc) with time, temperature, and/or humidity. One of the most promising organic thermoelectric materials, poly(3,4‐ethyelenedioxythiophene)‐polystyrene sulfonate (PEDOT‐PSS), is an MIEC. A previous study reveals that at high humidity, PEDOT‐PSS undergoes an ionic Seebeck effect due to mobile protons. Yet, this phenomenon is not well understood. In this work, the time dependence of the V_oc is studied and its behavior from the contribution of both charge carriers (holes and protons) is explained. The presence of a complex reorganization of the charge carriers promoting an internal electrochemical reaction within the polymer film is identified. Interestingly, it is demonstrated that the time dependence behavior of V_oc is a way to distinguish between three classes of polymeric materials: electronic conductor, ionic conductor, and mixed ionic–electronic conductor.     

Effect of maleic anhydride grafted polypropylene on the mechanical and morphological properties of chemically modified short‐pineapple‐leaf‐fiber‐reinforced polypropylene composites

With the rising cost of petroleum‐based fibers, the utilization of plant fibers in the manufacture of polymer–matrix composites is gaining importance worldwide. The scope of this study was to examine the perspective of the use of pineapple leaf fibers (PALFs) as reinforcements for polypropylene (PP). These fibers are environmentally friendly, low‐cost byproducts of pineapple cultivation and are readily available in the northeastern region of India. Here, both untreated and treated pineapple fibers were used. Maleic anhydride grafted polypropylene (MA‐g‐PP) was used as a compatibilizing agent. The polymer matrix of PP was used to prepare composite specimens with different volume fractions (5–20%) of fibers by the addition of 5% of MA‐g‐PP. These specimens were tested for their mechanical properties, and additional assessments were made via observations by scanning electron microscopy, thermogravimetric analysis, and IR spectroscopy. Increase in the impact behavior, flexural properties, and tensile moduli of the composites were noticed, and these were more appreciable in the treated fibers mixed with MA‐g‐PP. PALF in 10 vol % in PP mixed with MA‐g‐PP was the optimum and recommended composition, where the flexural properties were the maximum. The impact strength and the tensile modulus were also considerably high. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Dip-coated hydrotungstite thin films as humidity sensors

Thin films of a hydrated phase of tungsten oxide, viz. hydrotungstite, have been prepared on glass substrates by dipcoating method using ammonium tungstate precursor solution. X-ray diffraction shows the films to have a strongb — axis orientation. The resistance of the films is observed to be sensitive to the humidity content of the ambient, indicating possible applications of these films for humidity sensing. A homemade apparatus designed to measure the d.c. electrical resistance in response to exposure to controlled pulses of a sensing gas has been employed to evaluate the sensitivity of the hydrotungstite films towards humidity.