Temperature-Responsive Poly(N-Isopropylacrylamide-Acrylamide-Phenylboronic Acid) Microgels for Stabilization of Silver Nanoparticles

Poly(N-isopropylacrylamide-acrylamide-phenylboronic acid) [P(NIPAM-AAm-PBA)] microgels of uniform size were prepared by the chemical reaction of 3-aminophenylboronic acid with poly(N-isopropylacrylamide-acrylamide-acrylic acid) [P(NIPAM-AAm-AA)] microgels in aqueous medium in the presence of N-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride catalyst via carbodiimide coupling. Silver (Ag) nanoparticles were prepared using seed-mediated growth method and stabilized in P(NIPAM-AAm-PBA)] microgels. Ag nanoparticles and hybrid microgels were characterized by transmission electron microscopy, UV–visible, and dynamic light scattering techniques. The temperature-responsive behavior of hybrid microgels was found to be similar to that of the pure microgels. The value of volume transition temperature of hybrid microgels was found to be slightly higher than that of pure microgels due to shielding effect of Ag nanoparticles present on the surface of microgel particle. The decrease in the size of hybrid microgels as compared to that of pure microgels in swollen state is due to physical cross-linking by Ag nanoparticles inside the network of microgels. The stable hybrid polymer microgel system has a potential to be used for different applications.     

Evaluation of labelling conditions,quality control and biodistribution study of 99mTc-5-aminolevulinic acid (5-ALA): a potential liver imaging agent

Labelling of 5-aminolevulinic acid (5-ALA) with ^99mTc was achieved by using SnCl₂·2H₂O as reducing agent. Radiochemical purity and labelling efficiency was determined by instant thin layer chromatography/paper chromatography. Efficiency of labelling was dependent on many parameters such as amount of ligand, reducing agent, pH, and time of incubation. ^99mTc labelled 5-ALA remained stable for 24 h in human serum. Tissue biodistribution of ^99mTc-5-ALA was evaluated in Sprague–Dawley rats. Biodistribution study (% ID/g) in rats revealed that ^99mTc-5-ALA was accumulated significantly in liver, spleen, stomach and intestine after half hour, 4 and 24 h. Significant activity was noted in bladder and urine at 4 h. High liver uptake of ^99mTc-5-ALA makes it a promising liver imaging agent.     

Carbon/titanium oxide supported bimetallic platinum/iridium nanocomposites as bifunctional electrocatalysts for lithium-air batteries

Platinum (Pt) and iridium (Ir) catalysts are well known to strongly enhance the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics, respectively. Pt–Ir-based bimetallic compounds along with carbon-supported titanium oxides (C–TiO₂) have been synthesized for the application as electrocatalysts in lithium oxygen batteries. Transition metal oxide-based bimetallic nanocomposites (Pt–Ir/C–TiO₂) were prepared by an incipient wetness impregnation technique. The as-prepared electrocatalysts were composed of a well-dispersed homogenous alloy of nanoparticles as confirmed by X-ray diffraction patterns and Fourier transform scanning electron microscopy analyses. The electrochemical characterizations reveal that the Pt–Ir/C–TiO₂ electrocatalysts were bifunctional with high activity for both ORR and OER. When applied as an air cathode catalyst in lithium-air batteries, the electrocatalyst improved the battery performance in terms of capacity, reversibility, and cycle life compared to that of cathodes without any catalysts.     

Kinetics of pyrolysis of sugarcane bagasse: effect of catalyst on activation energy and yield of pyrolysis products

Cellulose - In this work we have attempted to use biomass as energy source which is abundantly available throughout the world. The work is focused on pyrolysis of sugarcane bagasse in a...     

Gravitational Collapse with Heat Flux and Gravitational Waves

In this paper, we investigated the cylindrical gravitational collapse with heat flux by considering the appropriate geometry of the interior and exterior spacetimes. For this purpose, we matched collapsing fluid to an exterior containing gravitational waves.The effects of heat flux on gravitational collapse are investigated and matched with the results obtained by Herrera and Santos (Class. Quantum Gravity 22:2407, 2005).     

Temperature and composition dependence of magnetic properties of cobalt–chromium co-substituted magnesium ferrite nanomaterials

The temperature and composition dependence of magnetic properties of Co–Cr co-substituted magnesium ferrite, Mg_1−xCo_xCr_xFe_2−xO₄ (x=0.0–0.5), prepared by novel polyethylene glycol assisted microemulsion method, are studied. The synthesized materials are characterized by the Mössbauer spectrometer and standard magnetic measurements. Major hysteresis loops are measured up to the magnetic field of 50 kOe at 300, 200 and 100 K. The high field regimes of these loops are modeled using the Law of Approach to saturation to determine the first-order cubic anisotropy coefficient and saturation magnetization. Both the saturation magnetization and the anisotropy coefficient are observed to increase with the decrease in temperature for all Co–Cr co-substitution levels. Also, both the saturation magnetization and the anisotropy coefficient achieved maximum value at x=0.3 and x=0.2, respectively. Explanation of the observed behavior is proposed in terms of the site occupancy of the co-substituent, Co²⁺ and Cr³⁺ in the cubic spinel lattice.     

Effect of Cu-Cr co-substitution on magnetic properties of nanocrystalline magnesium ferrite

This study deals with the temperature and composition dependence of magnetization and magnetic anisotropy of Cu²⁺-Cr³⁺ co-substituted magnesium ferrite, Mg_1−xCu_xCr_xFe_2−xO₄ (x=0.0-0.5). The synthesized materials are characterized using thermo gravimetric analysis, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray fluorescence, Mössbauer spectrometer, superconducting quantum interference device magnetometer and vibrating sample magnetometer. The M-H loops measured up to 50 kOe at 300, 200 and 100 K, revealed narrow hysteresis curves with a coercive field and saturation magnetization varying for different compositions. The high field regimes of these loops are modeled using the Law of Approach to saturation to extract anisotropy information and saturation magnetization. Both the saturation magnetization and the anisotropy constant are observed to increase with the decrease in temperature while decrease with the Cu-Cr co-substituents for all the samples. Explanation of the observed behavior is proposed in terms of the preference of the co-substituent ions of Cu²⁺ and Cr³⁺ and their predominant choice to substitute into the octahedral sites of the cubic spinel lattice.     

Meliloester, a new melilotic ester from Melilotus alba

A new melilotic ester, meliloester [2-ethyl-hexyl-3-(2-hydroxyphenyl) propionate], was isolated from the whole plant of Melilotus alba. Its structure was elucidated on the basis of spectroscopic and mass spectrometric analyses, including EI-MS, HR-MS, and UV, IR, 1D and 2D-NMR spectroscopic studies.     

A new megastigmane glycoside, phoenixoside A, from Phoenix dactylifera

A new megastigmane glycoside, phoenixoside A (1), has been isolated from the n-butanol--soluble fraction of seeds of Phoenix dactylifera. The structure was characterized as (6S,7Z,9R)-hydroxy-3-oxo-ionol-9-O-beta-D-glucopyranosyl-(1" --> 6')-beta-D-glucopyranoside on the basis of 1D and 2D NMR spectroscopy, high-resolution mass spectrometry, and CD spectroscopy.     

State Estimation of an Underwater Markov Chain Maneuvering Target Using Intelligent Computing

In this study, an application of deep learning-based neural computing is proposed for efficient real-time state estimation of the Markov chain underwater maneuvering object. The designed intelligent strategy is exploiting the strength of nonlinear autoregressive with an exogenous input (NARX) network model, which has the capability for estimating the dynamics of the systems that follow the discrete-time Markov chain. Nonlinear Bayesian filtering techniques are often applied for underwater maneuvering state estimation applications by following state-space methodology. The robustness and precision of NARX neural network are efficiently investigated for accurate state prediction of the passive Markov chain highly maneuvering underwater target. A continuous coordinated turning trajectory of an underwater maneuvering object is modeled for analyzing the performance of the neural computing paradigm. State estimation modeling is developed in the context of bearings only tracking technology in which the efficiency of the NARX neural network is investigated for ideal and complex ocean environments. Real-time position and velocity of maneuvering object are computed for five different cases by varying standard deviations of white Gaussian measured noise. Sufficient Monte Carlo simulation results validate the competence of NARX neural computing over conventional generalized pseudo-Bayesian filtering algorithms like an interacting multiple model extended Kalman filter and an interacting multiple model unscented Kalman filter.