A Novel Approach to Improve Properties of BiFeO3 Nanomultiferroics

In this study we report the synthesis of Bi_1?xIn_xFe_1?yTi_yO₃ (0 ≤ x ≤ 0.1, 0 ≤ y ≤ 0.05) nanoparticles by a simple cost effective solution combustion method. Pure BFO samples shows distorted rhombohedral perovskite structure with space group R3c which is also supported by Fourier transform infrared spectra study. The codoping of In and Ti at A–B sites of BFO (BIFTO) partially distorts the crystal structure, increases the lattice strain, reduces the average particle size (14 nm), and increases the Fe³⁺/Fe²⁺ ratio which significantly affect the observed results. The saturation magnetization increases significantly upon codoping (4.60 emu/gm) by about 12 times than that of pure BFO (0.4 emu/gm). The improved ferromagnetic properties upon codoping is further manifestated in large value of linear magnetoelectric coupling coefficient (4.8 mV/cmOe) which further provides an indirect evidence for the collapse of space modulated spin structure. The activation energy increases with codoping (0.68 eV), although less than 1 eV which indicates that the conduction is still dominated by charged defects.     

A study on the sorption of NO3− and F− on the carboxymethylated starch‐based hydrogels loaded with Fe2+ ions

Using the principle of geochemistry of fluoride, green and cost effective anion adsorbents were developed for the removal of F^? from water systems. The scheme was further applied for the removal of NO₃^? also. Carboxymethylated starch functionalized through network formation with acrylamide was used as adsorbent, and the resultant hydrogels were loaded with Fe²⁺ ions to generate anchorage for the anions. Sorption of Fe²⁺ was studied as a function of different factors such as time, temperature, pH, and ion strength. The network having the highest Fe²⁺ uptake was loaded with the Fe²⁺ ions under optimum conditions and used for the sorption of F^? and NO₃^?. High efficiency has been observed for F^?, as even up to 100% uptake has been observed within just 10 minutes. The support shows high selectivity for NO₃^?, which was used as anion reference. Thermodynamics of sorption confirms low order and low energy processes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Uranyl ions uptake on poly(AAc/AAm)-cl-N,N-MBAAm hydrogel

In the present article, we report two well-characterized hydrogels for the adsorption of uranyl ions from 5% NaCl solution. The hydrogel was synthesized by free radical initiation from acrylamide and acrylic acid using N,N-methylenebisacrylamide as crosslinker. In order to improve ion uptake performance, the hydrogel was hydrolyzed to partially convert some of the amide groups into carboxylate groups. The uranyl ion adsorption was studied as a function of hydrogel structure, uranyl ions concentration, pH, temperature, and mass of hydrogel. The partially hydrolyzed hydrogel exhibited the maximum uranyl ion uptake of 236.6 mgg⁻¹ in 480 min at 45 °C and at pH 13. Good reproducibility of results was observed and the evidence of sorption at the optimum pH and ion concentration was obtained by comparison of FTIR spectra of the precursor and uranyl ions loaded hydrogels. The performance of both the hydrogels was found to be higher than that of a commercial resin, Amberlite IRC-718. The experimental data shows good match with Langmuir and Freundlich isotherms and pseudo-first order kinetics.     

Measurement of Plasma Density in Brass Arc Plasma at Atmospheric Pressure Using a Langmuir Single Probe

In this work, we construct electrodes of brass to produce plasma by arc discharge and is characterized by using a movableLangmuir single probe. It is a simple w...     

Performance analysis of earth-pipe-air heat exchanger for winter heating

Earth-pipe-air heat exchanger (EPAHE) systems can be used to reduce the heating load of buildings in winter. A transient and implicit model based on computational fluid dynamics is developed to predict the thermal performance and heating capacity of earth-air-pipe heat exchanger systems. The model is developed inside the FLUENT simulation program. The model developed is validated against experimental investigations on an experimental set-up in Ajmer (Western India). Good agreement between simulated results and experimental data is obtained. Effects of the operating parameters (i.e. the pipe material, air velocity) on the thermal performance of earth-air-pipe heat exchanger systems are studied. The 23.42 m long EPAHE system discussed in this paper gives heating in the range of 4.1-4.8 °C for the flow velocities 2-5 m/s. Investigations on steel and PVC pipes have shown that performance of the EPAHE system is not significantly affected by the material of the buried pipe. Velocity of air through the pipe is found to greatly affect the performance of EPAHE system.     

Inversion,chemical complexity,and interstitial transport in spinels

Spinels with the generic chemical formula AB₂O₄ have potential applications in nuclear energy and batteries. In both cases, their functionality is related to mass transport through the crystal. Here, using long-time atomistic simulations, we examine the impact of the cation structure on interstitial transport in two spinel chemistries, inverse MgGa₂O₄ and double MgAlGaO₄. We emphasize two aspects of the transport properties: the unit mechanisms that are described by individual barriers, for which we introduce pole-figure-like plots, and the aggregate behavior of those unit mechanisms. Compared to previous work on normal spinels, we find that inversion significantly reduces the rate of interstitial transport in these structures and has an impact on the stability of defects as they move through the lattice. In particular, B cation interstitials are found to be kinetically stable only in the inverse MgGa₂O₄. These results provide new insight into relationship between structure, chemistry, and transport in spinels.     

Polymers from renewable resources: Kinetics studies of the radiochemical graft copolymerization of styrene onto cellulose extracted from pine needles and the effect of some additives on the grafting parameters in an aqueous medium

In an attempt to develop an alternative to petro‐based polymers, we graft‐copolymerized cellulose isolated from the needles of Pinus roxburghii with styrene in a limited aqueous medium in air by simultaneous irradiation using gamma rays as the initiator. The optimum conditions for obtaining maximum grafting were determined as a function of monomer concentration, total dose of irradiation, and amount of water. Maximum percentage of grafting (P_g; 79.9) was obtained at a total dose of 1.152 × 10⁴ Gy with 1.325 × 10^?4 mol of styrene. The effect of methanol, LiNO₃, Cu(NO₃)₂, Mohr's salt, H₂SO₄, HNO₃, and AcOH on P_g was studied. All the additives were found to decrease graft yield, contrary to some reported studies. Total percentage conversion and rates of polymerization, grafting, and homopolymerization were evaluated. Evidence of grafting was provided by the characterization of cellulose and its graft copolymers by Fourier transform infrared spectroscopy, thermogravimetry, and observation of the swelling behavior in some solvents. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1490–1500, 2002     

Use of novel hydrogels based on modified cellulosics and methacrylamide for separation of metal ions from water systems

Interpenetrating networks (IPNs) based on extracted cellulose and its derivatives such as hydroxypropyl cellulose (HPC), cyanoethylcellulose, hydroxyethylcellulose, hydrazinodeoxycellulose, cellulosephosphate with methacrylamide (MAAm), and N,N‐methylene bisacrylamide were synthesized at reaction conditions evaluated for optimum network yield as a function of irradiation dose, concentrations of monomer and crosslinker, and amount of water. These networks were used in sorption of Fe²⁺, Cu²⁺, and Cr⁶⁺ ions. The networks were further functionlized by means of partial hydrolysis with 0.5N NaOH and metal ion sorption studies were carried out. Appreciable amount of all the three ions was sorbed and partial functionalization of the hydrogels results in selectivity in ion sorption with enhanced affinity for Fe²⁺ ions and total rejection of Cr⁶⁺ ions. These results are of interest for the development of low‐cost technologies based on smart hydrogels. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 667–671, 2002