Efficient photocatalytic degradation of bisphenol A by green synthesized CuO decorated nickel hexacyanoferrate nanocomposite

Bisphenol A (BPA), a chemical additive in polycarbonate plastics and epoxy resins, is suspected to be an endocrine-disrupter. Extensive use and irregular treating methods have led to frequent detection of BPA in wastewater, raising demand for their removal by efficient nanomaterials-based technique. Nanocomposite CuO@NiHCF was synthesized via green method using Citrus aurantium peel extract. Crystalline structure (particle size <50 nm) of CuO@NiHCF was analysed by microscopic and spectroscopic analysis. This nanocomposite showed 97% degradation of BPA (50 mg L⁻¹) at neutral pH in sunlight. Moreover, improved particle stability (zeta potential: −56.2 mV; 2.0 eV) and high surface area, pore volume (81 m²g⁻¹, 13.9 nm) resulted from synergism of NiHCF (−26.3 mV; 2.4 eV), and CuO (−11.5 mV; 1.9 eV) led to efficient photodegradation of BPA. Degradation of BPA was found photo-adsorptive. Moreover, degradation was carried out by OH radicals based with ring-opening mechanisms by GC–MS. High efficiency and sustainability of CuO@NiHCF were revealed by its multiple reusability (n = 10), leading to a promising and sustainable photocatalyst.     

Silver-Modified CrO2 of Core–Shell Nanoparticles and their Magnetic and Impedance Properties

A chemical CrO₃→CrO₂ transformation reaction occurs in the presence of Ag⁺ species forming CrO₂ core–shell magnetic nanoparticles. The process involves heating CrO₃ with AgNO₃ in an aqueous solution in ambient air at a low temperature of 330–350 K. Shell thickness (diamagnetic amorphous silver) is controlled to be ∼2 nm tunable to the magnetic and impedance properties. Improved coercivity H _c=75.7 mT and the Curie temperature T _C=415 K are found with saturation magnetization M _s = 80 Am²/kg after annealing the sample at 573 K in air for 2 h. On heating, the impedance (or electrical resistance) varies steadily through a maximum in the T _C point in a typical half-metallic ceramic behavior. In a dynamic response to frequency f , the T _C increases from 418 K at 1 kHz to as high a value as 505 K at 1 MHz. A nearly f independent and low value of dissipation factor φ as 0.05 is promising for low power loss high-frequency applications of such CrO₂ particles.     

Studies on the salt concentration of a PVdF–PVC based polymer blend electrolyte

To investigate the effects of salt concentration, LiBF₄ was incorporated into a PVdF–PVC based polymer blend and thin electrolytes were prepared by solution casting technique. The obtained thin films were subjected to various characterizations such as FTIR, XRD and TG/DTA analysis to study their complex behaviour, amorphicity and thermal stability, respectively. The ionic conductivities of the electrolytes were measured by AC impedance. A PVdF (80)–PVC (20)–LiBF₄ (8 wt%) polymer electrolyte was found to have high conductivity compared to other complexes. Similar investigations were also repeated with a LiClO₄ salt in the above blend and the electrical conductivity was found to be higher in the polymer complex having 8 wt% of salt concentration.     

Chemo‐enzymatic synthesis and evaluation of novel structured phenolic lipids as potential lipophilic antioxidants

Chemo‐enzymatic synthesis of structured triacylglycerol bearing ferulic acid as a phenolic acid at sn‐1/3 position is described in the present work. Four compounds of varying chain lengths, namely 3‐(4‐hydroxy‐3‐methoxy‐phenyl)‐acrylic acid‐2,3‐bis‐hexanoyloxy‐propyl ester, 3‐(4‐hydroxy‐3‐methoxy‐phenyl)‐acrylic acid‐2,3‐bis‐octanoyloxy‐propyl ester, 3‐(4‐hydroxy‐3‐methoxy‐phenyl)‐acrylic acid‐2,3‐bis‐dodecanoyloxy‐propyl ester, and 3‐(4‐hydroxy‐3‐methoxy‐phenyl)‐acrylic acid‐2,3‐bis‐9‐octadecenoyloxy‐propyl ester were synthesized, and their structures were confirmed by IR, NMR, and MS. Antioxidant activity of the structured phenolic lipids were evaluated using three different in vitro antioxidant assays such as 2, 2‐diphenyl‐1‐picrylhydrazyl free radical (DPPH^•) scavenging, antioxidant potency in lipid matrix using rancimat, and by the rate of inhibition of autoxidation of linoleic acid in micelles. Ferulic acid and dodecylgallate were used as reference antioxidant compounds. DPPH^• assay did not show any improvement in the antioxidant activity of ferulic acid with lipophilic modification. However, the antioxidant potency of the structured phenolic lipids measured by rancimat method as well as by the rate of inhibition of autoxidation of linoleic acid in micelle showed improvement in antioxidant activity compared to ferulic acid. This is probably due to better solubility of the synthesized phenolic lipids in a hydrophobic medium and appropriate anchorage in Tween 20 micelle. The observed activities of the structured phenolic lipids are comparable to dodecyl gallate in rancimat assay, but superior to dodecyl gallate in Tween 20 micellar system.     

Efficient modeling and evaluation of fiber-fed microcellularnetworks in a land mobile channel using a GMSK modem scheme

Fiber feeders have been proposed for simplifying the base station in microcells, and thus make feasible the use of the microcellular architecture to overcome the barrier posed by the finite available spectra. We provide an analytical model to evaluate the exact error performance of the system, which accounts for the statistical effects in the mobile channel and the nonlinearity of the laser diode. The nonlinearity of the optical source coupled with the fading nature of the wireless channel mandates a solution based on simulation. However, the computer run time for the simulation is prohibitive, virtually rendering the model useless. We propose a computer-amenable “simplified model” which reduces the computation time immensely and also provides reasonably tight bounds. The BER performance for various channel conditions is evaluated using both models, and comparative studies are made on fiber-optic and non-fiber-optic systems. The tradeoff between the system performance and system capacity is discussed. Results obtained justify the use of fiber-optic feeders for future microcellular systems from a BER-performance point of view     

Neutron activation analysis of respirable mica samples and their pathological effects in lungs of rats

Instrumental and radiochemical neutron activation analyses (INAA, RNAA) have been used to quantify the different elements present in mica samples derived from Indian mines and a factory, together with USGS standards using high-resolution gamma-ray spectrometry. Both samples revealed the presence of several toxic elements in appreciable quantities. When tested in a rat model system over a period of 360 days after intratracheal injection of mica samples of respirable size (50 mg/animal), the animals which received the factory sample containing shellac exhibited enhanced dust-induced pulmonary reaction together with characteristic abscess formation at later periods. The significance of these findings is discussed.     

Long-distance optical guiding of colloidal particles using holographic axilens

We report the use of an aspheric holographic optical element (axilens) that essentially combines the properties of the long focal depth of an axicon and the high energy concentration of a conventional spherical lens for long-distance guiding of microscopic objects. With the use of the axilens, polystyrene spheres (~6 μm diameter) could be transported over a distance of ~16 mm that was ~3 times longer compared with that obtained using a spherical lens of focal length identical to the mean focal length of the axilens. Further, due to the availability of good on-axis power density, even objects having very marginally higher refractive index than the medium (differing only at third decimal place) could be guided with a guiding speed of ~5 μm/s.     

Design and development of powder processed Fe–P based alloys

The present investigation deals with designing Fe, Fe–P binary and Fe–P–Si ternary alloys produced by an in-house developed powder metallurgical technique based on ‘Hot Powder Preform Forging’. Proper soaking of preforms at high temperature (1050 °C) eliminates iron-phosphide eutectic and brings entire phosphorus into solution in iron. Attempting hot forging thereafter completely eliminates hot as well as cold shortness and thereby helps to form these preforms (alloys) into very thin sheets of 0.5 mm. The use of costly hydrogen atmosphere during sintering has been eliminated by the addition of carbon as a reducing agent to form CO gas within the compact by reacting with oxygen of iron powder particles. The glassy ceramic coating applied over the compact serves as a protective coating to avoid atmospheric oxygen attack over the compact held at high temperature. These alloys so formed were subjected to density examination at various stages. Microstructural study has been carried out to estimate the grain size, volume percentage of porosity in the alloys, and uniform distribution of phosphorus and silicon in an iron matrix. X-ray diffraction studies of these alloys revealed the presence of only ferrite as product phase. Addition of alloying elements such as P and Si has improved the resistivity and magnetic properties of iron. Fe–0.07C–0.2O–0.3P–0.5Si alloy showed a resistivity as high as 31.7 μΩ cm. Coercivity values of the alloys ranged from 0.51 to 1.98 Oe. The total magnetic loss of Fe–0.07C–0.2O–0.3P–0.5Si alloy was the lowest (2.03 W/kg) amongst the alloys developed owing to its high resistivity combined with its low coercivity. These alloys which are drawn to thin sheets could find their possible application in the manufacturing of transformer cores.