Modification in the transport and morphological properties of solid polymer electrolyte system by low-energy ion irradiation

The poly(ethylene oxide) (PEO)-based solid polymer electrolyte (SPE) systems consisting of NaBr as a dopant salt are prepared. The stable PEO:NaBr system with 3 wt% of NaBr was subjected to low-energy ion beam irradiation to bring in morphological modification. The irradiated samples are studied using complex impedance spectra to evaluate electrical conductivity and relaxation process in the system. The studies show an increase in conductivity by one order magnitude in the irradiated systems. The dielectric loss tangent (tanδ) curves show a single peak due to strong coupling of ion transport with segmental motion. The resultant relaxation time τ exhibits a continuous decrease indicating increase in segmental dynamics as a result of increased amorphous content in the system. The temperature-dependent studies also indicate that the irradiated systems are more disordered/amorphous compared to pure systems. This fact is further supported by XRD, by observing an increase in peak width associated with reduction in peak intensity. The Raman spectra also support the change in morphology of the system by the appearance of disordered-longitudinal acoustic mode band.     

An Efficient Synthesis of 4‐Arylmethylidene‐3‐substituted‐Isoxazol‐5(4H)‐ones in Aqueous Medium

A series of 4‐arylmethylidene‐3‐substituted‐isoxazol‐5(4H)‐ones were efficiently synthesized by eco‐benign, one pot uncatalyzed reaction of β‐keto‐ester, hydroxylamine hydrochloride, and aromatic aldehyde with electron donating substituent in water.     

Ion induced controlled modifications in structural and optical properties of indium oxide thin films – studies with 25‐keV Co− and N+ beam implantations

Two sets of indium oxide thin films (~150 nm) grown on quartz substrates using thermal evaporation technique were processed separately with 25‐keV Co^? and N⁺ ions with several fluences ranging from 1.0 × 10¹⁵ to 1.0 × 10¹⁶ ions/cm². The pristine and the ion implanted films were characterized by Rutherford backscattering spectroscopy (RBS), X‐ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and UV–Vis spectrometry. The RBS spectra reveal signature of only cobalt and nitrogen in accordance to their fluences confirming absence of any contamination arising due to ion implantation. An increase in the average crystallite size (from 13.7 to 15.3 nm) of Co^? ions implanted films was confirmed by XRD. On the other hand, the films implanted with N⁺ ions showed a decrease in the average crystallite size from 20.1 to 13.7 nm. The XRD results were further verified by SEM micrographs. As seen in AFM images, the RMS surface roughness of the samples processed by both ion beams was found to decrease a bit (29.4 to 22.2 nm in Co^? implanted samples and 24.2 to 23.3 nm in N⁺ implanted samples) with increasing fluence. The Tauc's plot deduced from UV–visible spectroscopy showed that the band gap decreases from 3.54 to 3.27 eV in Co^? implanted films and increases from 3.38 to 3.58 eV for films implanted with N⁺ ions. The experimental results suggest that the modifications in structural and optical properties of indium oxide films can be controlled by optimizing the implantation conditions. Copyright © 2017 John Wiley & Sons, Ltd.     

50 keV H+ ion beam irradiation of Al doped ZnO thin films: Studies of radiation stability for device applications

Thin films of Al doped ZnO (Al:ZnO) were deposited on two substrates (Si and glass) at room temperature and 300°C using DC magnetron sputtering. These films were bombarded with 50 keV H⁺ beam at several fluences. The pristine and ion beam irradiated films were analysed by X‐ray diffraction, Raman spectroscopy, scanning electron microscopy, and UV‐Vis spectroscopy. The X‐ray diffraction analysis, Hall measurements, Raman and UV‐Vis spectroscopy confirm that the structural and transport properties of Al:ZnO films do not change substantially with beam irradiation at chosen fluences. However, in comparison to film deposited at room temperature, the Al:ZnO thin film deposited at 300°C shows increased transmittance (from 70% to approximately 90%) with ion beam irradiation at highest fluence. The studies of surface morphology by scanning electron microscopy reveal that the ion irradiation yields smoothening of the films, which also increases with ion fluences. The films deposited at elevated temperature are smoother than those deposited at room temperature. In the paper, we discuss the interaction of 50 keV H⁺ ions with Al:ZnO films in terms of radiation stability in devices.     

Evidence from Raman spectroscopy that InhA, the mycobacterial enoyl reductase, modulates the conformation of the NADH cofactor to promote catalysis

InhA, the enoyl reductase from Mycobacterium tuberculosis, catalyzes the NADH-dependent reduction of trans-2-enoyl-ACPs. In the present work, Raman spectroscopy has been used to identify catalytically relevant changes in the conformation of the nicotinamide ring that occur when NADH binds to InhA. For 4(S)-NADD, there is an 11 cm-1 decrease in the wavenumber of the C4-D stretching band (nuC-D) and a 50% decrease in the width of this band upon binding to InhA. While a similar reduction in line width is observed for the corresponding band arising from 4(R)-NADD, nuC-D for this isomer increases 34 cm-1 upon binding to InhA. These changes in nuC-D indicate that the nicotinamide ring adopts a bound conformation in which the 4(S)C-D bond is in a pseudoaxial orientation. Mutagenesis of F149, a conserved active site residue close to the cofactor, demonstrates that this enzyme-induced modulation in cofactor structure is directly linked to catalysis. In contrast to the wild-type enzyme, Raman spectra of NADD bound to F149A InhA resemble those of NADD in solution. Consequently, F149A is no longer able to optimally position the cofactor for hydride transfer, which correlates with the 30-fold decrease in kcat and 2-fold increase in D(V/KNADH) caused by this mutation. These studies thus substantiate the proposal that hydride transfer is promoted by pseudoaxial positioning of the NADH pro-4S bond, and indicate that catalysis of substrate reduction by InhA results, in part, from correct orientation of the cofactor in the ground state.     

An automated method for in vitro anticancer drug efficacy monitoring based on cell viability measurement using a portable photodiode array chip

An integrated circuit (IC) bipolar semiconductor photodiode array (PDA) microchip system coupled with light emitting diodes (LEDs) was used for rapid, automated cell viability measurements and high-throughput drug efficacy monitoring. Using the absorption property of trypan blue dye against the red light emitted by LEDs, we determined the effect of three anticancer drugs, viz., camptothecin (CAM), sodium salicylate (Na-Sal) and naringenin (Nar) on the cell viability of human promyelocytic leukemia cells (HL-60) and human embryonic kidney cells (HEK-293). Cell viabilities were measured based on the relative reduction in the photo responses of the photodiodes, covered with known concentration of trypan blue-stained cells. The developed method offers greater sensitivity and hence an excellent estimation of cell viability, but without all the hassle of conventional methods. Flow cytometric measurement and confocal microscopy were applied as complementary techniques for further validation of the results. The work presented here has important implications with regard to high-throughput measurement of optimal concentrations of different drugs against different cell lines in vitro.     

Neuroprotective Potential of Chrysin: Mechanistic Insights and Therapeutic Potential for Neurological Disorders

Chrysin, a herbal bioactive molecule, exerts a plethora of pharmacological effects, including anti-oxidant, anti-inflammatory, neuroprotective, and anti-cancer. A growing body of evidence has highlighted the emerging role of chrysin in a variety of neurological disorders, including Alzheimer’s and Parkinson’s disease, epilepsy, multiple sclerosis, ischemic stroke, traumatic brain injury, and brain tumors. Based on the results of recent pre-clinical studies and evidence from studies in humans, this review is focused on the molecular mechanisms underlying the neuroprotective effects of chrysin in different neurological diseases. In addition, the potential challenges, and opportunities of chrysin’s inclusion in the neurotherapeutics repertoire are critically discussed.     

Xantphos-ligated palladium dithiolates: An unprecedented and convenient catalyst for the carbonylative Suzuki–Miyaura cross-coupling reaction with high turnover number and turnover frequency

Xantphos- and dithiolate-ligated macrocyclic palladium complexes as an efficient and stable catalyst for the carbonylative Suzuki–Miyaura cross-coupling reaction have been synthesized. The catalysts were characterized by ¹H-nuclear magnetic resonance (NMR), CHNS (carbon, hydrogen, nitrogen, and sulfur) analysis, melting point analysis, and ³¹P-NMR spectroscopy. Several sensitive functional groups (e.g., –NO₂, –F, –Cl, –Br, –NH₂, and –CN) on the aromatic ring were well tolerated in the carbonylative Suzuki–Miyaura coupling reaction. The present palladium complexes produce six times higher turnover number (TON) and five times higher turnover frequency (TOF) compared with conventional homogeneous palladium precursors. Maximum TONs in the range of 10⁵ to 10⁶ and TOF in the range of 10⁴ to 10⁵ could be generated by a very low amount of catalyst loading (10^–5 mol%).     

Vitamin B12 Plus Graphene Based Bio-Electrocatalyst for Electroreduction of Halocarbons in 1-Butyl-3-Methylimidazolium Tetrafluoroborate: A Special Use of the Synergism between Graphene,Ionic Liquid and Vitamin B12

Russian Journal of Electrochemistry - A bio-functional composite of vitamin B12 with graphene and ionic liquid in chitosan solution was prepared for the first time. The composite was tested for its...     

A tandem oxidative dearomatization/intramolecular Diels-Alder reaction: a short and efficient entry into tricyclic system of maoecrystal V

A short and efficient route to tricyclic ring system containing bridged bicyclo[2.2.2]octanone annulated with a lactone ring present in the maoecrystal is described. In-situ generation of spiroepoxycyclohexa-2,4-dienone and intramolecular cycloaddition are the key features of our approach.