Unconventional magnetism in ZnO nanorods

ABSTRACT

We report room temperature ferromagnetism in vacuum annealed ZnO nanorods. ZnO nanorods were annealed at 600°C for 6 hours in an annealing chamber with a pressure of 10^?6 Torr. Our study indicates that ZnO nanorods develop room temperature ferromagnetism due to the presence of oxygen vacancy defects in it. Presence of large surface area of nanorods and oxygen vacancy are mainly responsible for the observed magnetic behavior.     

Using light to control the interactions between self-rotating assemblies of active gels

Polymer gels undergoing the oscillating Belousov-Zhabotinsky (BZ) reaction exhibit an autonomous, periodic swelling and deswelling, where the mechanical oscillations are driven by the chemical reaction within the polymer network. Using computer simulations, we show that these BZ gels can undergo a form of auto-chemotaxis, enabling the gels to spontaneously move in response to self-generated chemical gradients. Focusing on four millimeter-sized pieces of these BZ gels, we show that the pieces can organize into self-rotating clusters that resemble a moving pinwheel or gear. By analyzing the factors that promote the formation of a single self-rotating cluster, we attempt to design systems of multiple, interacting gears. We show that light, which suppresses the oscillations of the gels, can be harnessed to promote the formation of two self-rotating clusters. These studies point to a novel form of photo-chemo-mechanical transduction, where light is utilized to control the conversion of chemical and mechanical energy in the system. Moreover, the interaction between the BZ gel gears reveals a new form of entrainment between these moving units. Namely, their coordinated motion is achieved through chemical coupling or communication, rather than a mechanical coupling. These findings can lead to the formation of chemically “communicating” devices that can be programmed to perform autonomous work through the use of light.     

Effect of the compatibilizer,on the engineering properties of TPV based on Hypalon® and PP prepared by dynamic vulcanization

Elastomeric Chlorosulfonated polyethylene (Hypalon^®) and thermoplastic Polypropylene (PP) based thermoplastic vulcanizates (TPVs) were prepared in presence of different doses of compatibilizer, maleic anhydride grafted PP (PP‐g‐MA) by employing dynamic vulcanization technique. The effect of incorporation in different proportions of compatibilizer on mechanical, spectral, morphological, thermal, and rheological properties of such TPVs was studied and the same were compared to that of virgin PP and amongst themselves. The mechanical analysis of the prepared TPVs exhibited significant improvements in stress at 25% modulus, ultimate tensile strength (UTS), and hardness values. FTIR studies revealed that a chemical interaction had taken place between Hypalon^® and functionalized compatibilizer during the process of dynamic vulcanization which led to an enhancement of interfacial adhesion between them. The two‐phase morphologies were clearly observed by scanning electron microscopic studies. The T_g values of Hypalon^® was modified in the TPVs as exhibited by differential scanning calorimetric studies. TGA studies indicated the increase in thermal stability of all TPVs with respect to the elastomeric Hypalon^®. Rheological properties showed that the compatibilizer reduces the melt viscosity of TPVs and thus facilitates the processibility of such TPVs. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40312.     

Improved energy recovery from dark fermented cane molasses using microbial fuel cells

A major limitation associated with fermentative hydrogen production is the low substrate conversion efficiency. This limitation can be overcome by integrating the process with a microbial fuel cell (MFC) which converts the residual energy of the substrate to electricity. Studies were carried out to check the feasibility of this integration. Biohydrogen was produced from the fermentation of cane molasses in both batch and continuous modes. A maximum yield of about 8.23 mol H₂/kg COD_removed was observed in the batch process compared to 11.6 mol H₂/kg COD_removed in the continuous process. The spent fermentation media was then used as a substrate in an MFC for electricity generation. The MFC parameters such as the initial anolyte pH, the substrate concentration and the effect of pre-treatment were studied and optimized to maximize coulombic efficiency. Reductions in COD and total carbohydrates were about 85% and 88% respectively. A power output of 3.02 W/m³ was obtained with an anolyte pH of 7.5 using alkali pre-treated spent media. The results show that integrating a MFC with dark fermentation is a promising way to utilize the substrate energy.     

Efficient UE mobility in multi-RAT cellular networks using SDN

Wireless Networks - Though, Software Defined Networking (SDN) started with the wired networks, several architectural solutions have been proposed to incorporate SDN in the wireless domain, to...     

Mechanistic study of Al electrodeposition from EMIC–AlCl3 and BMIC–AlCl3 electrolytes at low temperature

Aluminum was electrodeposited from two different ionic liquid electrolytes namely; 1-ethyl-3-methylimidazolicum chloride and AlCl₃ (EMIC–AlCl₃) and 1-butyl-3-methylimidazolium chloride (BMIC–AlCl₃) at 90 ± 2 °C. Nodular morphology of aluminum was obtained at the copper substrate. To evaluate the reaction mechanism, chronoamperometric study was adopted. From the chronoamperometric analysis, it was observed that the reaction was controlled by instantaneous three-dimensional diffusion process. The diffusion coefficient (D) of Al₂C₇⁻ was found to be 5.2–6.6 × 10⁻¹¹ m² s⁻¹ and 2.2 × 10⁻¹¹ m² s⁻¹ for EMIC–AlCl₃ and BMIC–AlCl₃ ionic liquid electrolytes, respectively. The nuclei density of electrodeposited aluminum on the copper was also confirmed by scanning electron microscope wherein uniformly distributed aluminum nodules were observed.     

Recent advances in indium metallurgy: A review

The by-products of zinc refineries are used as the primary mineral resources for the commercial production of indium. The discarded LCDs containing adequate amount of indium is rather worth as its secondary resources compared to the by-products of zinc refineries. Mining and recycling rates of indium, respectively from minerals and waste LCDs are in progress to meet its huge demand. Recycling of the LCDs has been dominating over mining, as presently 480t of indium are produced annually from mining, however, that of 650t annually from recycling. Different aspects of the extractive metallurgy of indium are summarized in this review paper.     

A comparative study of SiAlON ceramics

Two different varieties of Si₃N₄ powders were used to prepare SiAlON ceramics. 100% β-Si₃N₄ was used from refractory grade powders (B1) and another purer 98% α-Si₃N₄ (50A) powder was used to prepare the SiAlON samples. Since SiC + SiAlON composites reportedly perform better, batches were prepared with 15% SiC addition to the refractory powders (B1) and 17.5% SiC was added to the other SiAlON composition (50A). The samples were gas pressure sintered at 1840 °C and at 22 bar with 1 h dwelling time. Thereby, we could achieve 97–98% theoretical density. The hardness was recorded 14–17 GPa while fracture toughness varied from 4.3 to 5 MPa m^1/2. Fretting experiments showed initial running-in period of 300 cycles for all the tribo-couples. After which, the steady state coefficient of frictions (COF) were achieved. Steel ball of 10 mm diameter, fretting against 50A composition, showed 0.6 average steady state COF while the same composition while fretting against alumina ball of the same diameter, showed 0.57 average steady state COF. Results have been compared with SiAlON composition derived from refractory powder (B1) and found that the 50A composition performs better under identical test conditions. Moreover, cytocompatibility study also suggests that the investigated 50A composition can be used as substrate to support cell adhesion and proliferation of L929 mouse fibroblast cell lines whereas B1 composition derived from refractory powders are toxic in nature.     

Synthesis,Characterization, and drug release study of acrylamide‐co‐itaconic acid based smart hydrogel

A new kind of pH and temperature responsive poly(acrylamide‐co‐itaconic acid) hydrogel was prepared by free radical polymerization using ammonium persulfate as initiator and different comonomer ratios. The hydrogels were characterized in terms of chemical composition, swelling‐deswelling behavior, morphology, crystallographic behavior, and drug release properties. All the hydrogels showed high swelling ability in aqueous solutions, the maximum being at pH 7. Swelling decreased on either side of pH 7 (i.e., both in acidic and alkaline region) and increased with increase in temperature. The hydrogel with 10 mol% itaconic acid (IA) absorbed maximum water among the copolymer gels. The cellular structures of the hydrogels were clearly revealed by microscopic analysis and SEM pictures. Swelling of the gels in water followed non‐Fickian type of diffusion principle. The hydrogel was proved to be a controlled release vehicle, for example in drug delivery by using its smart properties. The hydrogel with 10 mol% IA also absorbed maximum amount of drug (ascorbic acid) under study. Incorporation of drug in hydrogel matrix was established from XRD peak analysis. POLYM. ENG. SCI., 55:113–122, 2015. © 2014 Society of Plastics Engineers     

Modelling of flame temperature of solution combustion synthesis of nanocrystalline calcium hydroxyapatite material and its parametric optimization

Hydroxyapatite (HAp), an important bio-ceramic was successfully synthesized by combustion in the aqueous system containing calcium nitrate-di-ammonium hydrogen orthophosphate-urea. The combustion flame temperature of solution combustion reaction depends on various process parameters, and it plays a significant role in the phase formation, phase stability and physical characteristics of calcium hydroxyapatite powder. In this work, an attempt has been made to evaluate the influence of each selected process parameters on the flame temperature as well as physical characteristics of powder, and to select an optimal parameters setting using Taguchi method. A regression model has also been developed to correlate the input parameters, viz. batch size, diluents, fuel to oxidizer ratio and initial furnace temperature, with flame temperature of the solution combustion reaction. The adequacy of the developed model has been checked using analysis of variance technique.