Structural details, electrical properties, and electromagnetic interference shielding response of processable copolymers of aniline

Processable copolymers of aniline with 2-alkylanilines were prepared by in situ chemical oxidative polymerization route. Formation of copolymers was confirmed by X-ray diffractometer (XRD), UV–Vis, and solubility measurements. XRD revealed that copolymerization leads to increase in inter-chain spacing and reduction of doping levels. UV–vis results showed that incorporation of substituted anilines in copolymeric backbone leads to decrease in conjugation, the extent of which is directly related to size of alkyl substituent. The electrical conductivities of these copolymers were slightly less than pure polyaniline, but noticeable improvement in the solution processability was observed. In addition, these copolymers also provided shielding against electromagnetic interference (EMI) with ~99 % attenuation of incident energy. Among various copolymers, 95:5 copolymer of aniline with 2-isopropyl aniline (CP95Ip) gave best performance in terms of electrical conductivity (12.8 S/cm), solubility (4.9 g/L in N-methyl pyrrolidone), and EMI shielding effectiveness (?23.2 dB) values.     

Specific heat of hole-doped vanadates: Y1−xCaxVO3, Pr1-xCaxVO3 and Nd1−xSrxVO3

We have investigated the specific heat of hole-doped vanadium oxides Y_1−xCa_xVO₃ (0 ≤ x ≤ 0.11), Pr_1−xCa_xVO₃ (0 ≤ x ≤ 0.3) and Nd_1−xSr_xVO₃ (0 ≤ x ≤ 0.2) probably for the first time by applying the Modified Rigid ion model (MRIM). The results obtained on temperature dependent (1 K ≤ T ≤ 300 K) specific heat are in reasonably good agreement with the experimental data. The impact of lattice distortions on the elastic and thermal properties of the present Mott insulators is portrayed by an atomistic approach. The scope of further improvement in the present model has also been discussed.     

High flux mesoporous MCM-48 membranes: Effects of support and synthesis conditions on membrane permeance and quality

This communication reports experimental efforts to synthesize defect-free mesoporous MCM-48 membranes with improved gas flux. We demonstrate a facile and inexpensive method of synthesizing defect-free supported MCM-48 membranes with improved N₂ and CO₂ permeance (>2 × 10⁻⁷ mol/m² s Pa) employing asymmetric supports for the membrane synthesis which contain layers of macropores possessing different pore sizes. The membranes prepared on asymmetric -alumina supports displayed higher gas permeance than those fabricated on symmetric supports (N₂ permeance <10⁻⁷ mol/m² s Pa) as confirmed by unsteady-state gas permeation experiments. Further improvement in gas permeance was achieved by covering one face and the sides of the support with a ceramic tape during membrane synthesis.     

Rapid synthesis of thermally stable hydroxyapaptite

We have optimized the wet precipitation synthesis of hydroxyapaptite to obtain thermally stable powder in the short time span of 3 min. Exposure of the reaction mixture to 1000 W microwave for 3 min furnished hydroxyapatite, which was thermally stable at temperatures up to 1200 °C. Powders were analyzed for phase purity using X-ray crystallography; chemical composition was studied using Fourier transform infrared spectroscopy while particle morphology was analyzed using scanning electron microscopy.     

Enhancement of pro‐degradant performance in polyethylene/starch blends as a function of distribution

The effect of pro‐degradant distribution in polyethylene (PE)/starch blends on ultraviolet (UV) photo‐oxidative degradation was investigated. Two kinds of pro‐degradants, Fe and Co‐based, were used in this study. The distribution of pro‐degradants in the different phases was varied by a dual step process using a side‐feed on a reactive extruder. The variation in mechanical properties and evaluation of carbonyl groups by FTIR were conducted to investigate the effect of degradation following exposure to UV photo‐oxidative degradation. It was found that the variation in mechanical properties was higher when the pro‐degradants were distributed in the PE phase. The concentration of carbonyl groups increased as a function of UV exposure, and the concentration of carbonyl groups was higher when the pro‐degradants were distributed in the PE phase. Micro‐cracking was observed on the interface between starch and PE after adding the pro‐degradants. When the pro‐degradants were distributed in high‐density polyethylene (HDPE) phase, the micro‐cracks mainly appeared in HDPE matrix, and the density of micro‐crack was higher. In general, the function of the pro‐degradants in PE/starch blends was enhanced when their distribution was varied within HDPE phase. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Polyaniline–MWCNT nanocomposites for microwave absorption and EMI shielding

Highly conducting polyaniline (PANI)–multi-walled carbon nanotube (MWCNT) nanocomposites were prepared by in situ polymerization. The FTIR and XRD show systematic shifting of the characteristic bands and peaks of PANI, with the increase in MWCNT phase, suggesting significant interaction between the phases. The SEM and TEM pictures show thick and uniform coating of PANI over surface of individual MWCNT. Based on observed morphological features in SEM, the probable formation mechanism of these composites has been proposed. The electrical conductivity of PANI–MWCNT composite (19.7 S cm^?1) was even better than MWCNT (19.1 S cm^?1) or PANI (2.0 S cm^?1). This can be ascribed to the synergistic effect of two complementing phases (i.e. PANI and MWCNT). The absorption dominated total shielding effectiveness (SE) of ?27.5 to ?39.2 dB of these composites indicates the usefulness of these materials for microwave shielding in the Ku-band (12.4–18.0 GHz). These PANI coated MWCNTs with large aspect ratio are also proposed as hybrid conductive fillers in various thermoplastic matrices, for making structurally strong microwave shields.     

Protein–Energy Malnutrition: A Risk Factor for Various Ailments

The wheel of industrialization that spun throughout the last century resulted in urbanization coupled with modifications in lifestyles and dietary habits. However, the communities living in developing economies are facing many problems related to their diet and health. Amongst, the prevalence of nutritional problems especially protein–energy malnutrition (PEM) and micronutrients deficiencies are the rising issues. Moreover, the immunity or susceptibility to infect-parasitic diseases is also directly linked with the nutritional status of the host. Likewise, disease-related malnutrition that includes an inflammatory component is commonly observed in clinical practice thus affecting the quality of life. The PEM is treatable but early detection is a key for its appropriate management. However, controlling the menace of PEM requires an aggressive partnership between the physician and the dietitian. This review mainly attempts to describe the pathophysiology, prevalence and consequences of PEM and aims to highlight the importance of this clinical syndrome and the recent growth in our understanding of the processes behind its development. Some management strategies/remedies to overcome PEM are also the limelight of the article. In the nutshell, early recognition, prompt management, and robust follow up are critical for best outcomes in preventing and treating PEM.