Effect of 50 MeV Li+3 and 80 MeV C+5 ions’ beam irradiation on the optical,structural, chemical and surface topographic properties of PMMA films*

The self-standing films of polymethyl methacrylate (PMMA) were irradiated under vacuum with 50?MeV lithium (Li³⁺) and 80?MeV carbon (C⁵⁺) ions to the fluences of 3?×?10¹⁴, 1?×?10¹⁵, 1?×?10¹⁶ and 1?×?10¹⁷ ions µm^?2. The pristine and irradiated samples of PMMA films were studied by using ultraviolet–visible (UV–Vis) spectrophotometry, Fourier transform infrared, X-ray diffractrometer and atomic force microscopy. With increasing ion fluence of swift heavy ion (SHI), PMMA suffers degradation, UV–Vis spectra show a shift in the absorption band from the UV towards visible, attributing the formation of the modified system of bonds. E_g and E_a decrease with increasing ion fluence. The size of crystallite and crystallinity percentage decreases with increasing ion fluence. With SHI irradiation, the intensity of IR bands and characteristic bands of different functional groups are found to shift drastically. The change in (E_g) and (N) in carbon cluster is calculated. Shifting of the absorption band from the UV towards visible along with optical activity and as a result of irradiation, some defects are created in the polymer causing the formation of conjugated bonds and carbon clusters in the polymer, which in turn lead to the modification in optical properties that could be useful in the fabrication of optoelectronic devices, gas sensing, electromagnetic shielding and drug delivery.     

Synthesis of aminouracil-tethered tri-substituted methanes in water by iodine-catalyzed multicomponent reactions

Molecular Diversity - An efficient, mild and environmentally benign protocol has been developed for the synthesis of aminouracil-tethered tri-substituted methane derivatives. The three-component...     

An experimental approach to find aniline-formaldehyde co-polymers as effective inhibitor on the interface of low carbon steel immersed in 0.5N HCl mixtures

The usefulness of aniline formaldehyde (AF), a modern water-soluble composite in 0.5 ?N hydrochloric acid as inhibitor of corrosion for mild steel, has been studied using weight reduction method, test of electrochemical impedance and potentiodynamic polarization methods. According to the findings by weight loss methods, 12ppm of AF co-polymer at room temperature i.e. about 35° ?± ?1°C for 3h duration shows best performance on metal surface and exhibit 93.44% Inhibitor efficiency. The above said results has also being reviled from other examination methods, which shows that the AF follows the Langmuir isotherm, as well as the adsorption properties of the sampling supports the results as maximum IE of 95.05%, using EIS. The tafel and linear polarization results of maximum IE was found to be 94.81% and 94.96% respectively which was well aligned with an atomic force microscope (AFM) for surface morphology and found AF to be best suited corrosion inhibitor showing mixed type of nature, at defined parameters.     

Performance assessment of hybrid multiblock copolymers included with ionic liquid for fuel cell applications

To improve the proton conductivity and thermal stability of proton exchange membrane, hybrid poly (arylene ether) multiblock copolymers were synthesized by using 6F-bisphenol A monomer. The hydrophobic oligomers poly (arylene ether sulfone) containing 6F-bisphenol A with varying molecular weight were copolymerised with hydrophilic oligomer disulfonated poly (arylene ether ketone) containing pendant carboxylic acid group to prepare multiblock copolymers. For further enhancing the proton conductivity, ionic liquid is embedded into the synthesized multiblock copolymers to fabricate the hybrid multiblock membranes. The ¹H NMR studies confirmed the synthesis of oligomers and multiblock copolymers whereas the FT-IR spectra revealed the interaction of ionic liquid with the multiblock copolymers. The proton conductivity of the membranes has also been examined at different temperatures and the activation energy required for the proton transport was calculated by using Arrhenius equation. At 30 °C, the maximum proton conductivity of 0.14 S/cm were shown by hybrid membrane (with 50% ionic liquid, 6FB1/I.L-50%), which is of 3.5 times greater than that of pristine 6FB1 membrane. Compared with pristine membranes, the hybrid membranes exhibit improved oxidative, thermal and mechanical stability. Moreover, the scanning electron microscopy (SEM) investigation depicts better phase separation in hybrid membranes than pristine membranes by forming ionic clusters. The membranes have been tested in H₂/O₂ fuel cell and their performance is compared with the state-of-art Nafion 117 membrane.     

DFT study of structural and electronic properties of gallic acid and its anions in gas phase and in aqueous solution

Gallic acid, one of the naturally occurring antioxidants, has been characterized in terms of its structural and chemical properties using the density functional approach. The intramolecular interactions have been identified using natural bond orbital (NBO) analysis. The gallic acid anion and dianion have also been studied for determining the first two pK _a values. Further, an investigation of the molecular orbitals reveals a dependence of the frontier molecular orbitals on external factors, viz. pH and dielectric of the medium. Consequently, the electronic spectra have been simulated in a range of solvents using steered molecular dynamics. Furthermore, the IR and NMR spectra of the neutral and the deprotonated state have been simulated. Additionally, the spectra have been experimentally recorded to validate the methodology followed. The present work also examines the variation in global and local reactivities of gallic acid under the influence of external factors. Each atom has been quantitatively assessed for its susceptibility towards nucleophilic, electrophilic, and radical attack.     

Novel Hydrogels for Rhythmic Pulsatile Drug Delivery

Summary: We are investigating an autonomous glucose-driven hydrogel/enzyme-based device prototype for rhythmic, pulsed delivery of gonadotropin releasing hormone (GnRH). The device employs a pH-sensitive hydrogel membrane in conjunction with the enzyme glucose oxidase. This system delivers GnRH in rhythmic pulses when exposed to a constant level of glucose. These pulses result from autonomous pH oscillations inside the device that are created by an unstable nonlinear feedback between hydrogel permeability to glucose and production of acid by glucose oxidase. Previous versions of this prototype utilized p(N-isopropylacrylamide-co-methylacrylic acid) p(NIPA-co-MAA) hydrogels, with 10 mol% MAA incorporated. With this membrane, which undergoes a volume transition (VT) near pH 5, pH oscillations centered around pH 5 are observed. This range is too low to sustain oscillations in physiologically buffered media. To shift the operating pH of oscillations closer to physiologic pH, we have sought ways to increase the pH of the volume transition. In this study we show that increasing the side chain length of the α-alkylacrylic acid (RAA) comonomer enhances the overall hydrophobicity of the copolymer, and shifts the VT pH closer to physiological pH values. We also demonstrate the ability of such membranes to affect an alkaline shift in the range of oscillations in the prototype oscillator device.     

Quantum Capacitance of Mo2N MXene for Supercapacitor Applications

MXenes for supercapacitor (SC) electrodes is a very promising area of research. Supercapacitors are still behind batteries when to be used as primary energy source due to their low energy densities. Hence, additional research is vital to explore materials like MXenes for SC electrodes. The electronic properties of molybdenum nitride Mo₂N are studied and its quantum capacitance (QC) is calculated to explore its potential for SC electrodes. The MXene is found to be metallic in nature. The QC values for Mo₂N MXene are extremely high around Fermi level. Maximum value of 746.69 µF cm⁻² is achieved which is way higher than that of graphene. The value remains high for the negative bias voltage as well.     

Regioselective synthesis of pyrimidine-fused tetrahydropyridines and pyridines by microwave-assisted one-pot reaction

Molecular Diversity - A regioselective three-component reaction of α,β-unsaturated aldehydes, cyclic 1,3-dicarbonyls and 6-aminouracils in the presence of FeCl3·6H2O as catalyst...     

Structure of negative parity yrast bands in odd mass <Superscript>125–131</Superscript>Ce nuclei

The negative parity yrast bands of neutron-deficient ^125–131Ce nuclei are studied by using the projected shell model approach. Energy levels, transition energies and B(M1)/B(E2) ratios are calculated and compared with the available experimental data. The calculations reproduce the band-head spins of negative parity yrast bands and indicate the multi-quasiparticle structure for these bands.