Characterization and catalytic functionalities of copper oxide catalysts supported on zirconia

A series of zirconia supported copper oxide catalysts with varying copper loadings (1.2-19.1 wt %) were prepared by impregnation method. The catalysts were characterized by X-ray diffraction, UV-visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), and temperature-programmed desorption of CO2. Copper dispersion and metal area were determined by N2O decomposition method. X-ray diffraction patterns indicate the presence of crystalline CuO phase beyond 2.7 wt % of Cu on zirconia. UV-visible diffuse reflectance spectra suggest the presence of two types of copper species on the ZrO2 support. XPS peaks intensity ratio of Cu 2p3/2 and Zr 3d5/2 was compared with Cu dispersion calculated from N2O decomposition. TPR patterns reveal the presence of highly dispersed copper oxide at lower temperatures and bulk CuO at higher temperatures. The basicity of the catalysts was found to increase with Cu loading, and the activity of the catalysts was also found to increase with the increase in Cu loading up to 2.7 wt % Cu loading. The catalytic properties were evaluated for the dehydrogenation of cyclohexanol to cyclohexanone and were related to surface properties of the copper species supported on zirconia.     

Dependence of the fragility of a glass former on the softness of interparticle interactions

We study the influence of the softness of the interparticle interactions on the fragility of a glass former by considering three model binary mixture glass formers. The interaction potential between particles is a modified Lennard-Jones type potential, with the repulsive part of the potential varying with an inverse power q of the interparticle distance, and the attractive part varying with an inverse power p. We consider the combinations (12,11) (model I), (12,6) (model II), and (8,5) (model III) for (q,p) such that the interaction potential becomes softer from model I to III. We evaluate the kinetic fragilities from the temperature variation of diffusion coefficients and relaxation times, and a thermodynamic fragility from the temperature variation of the configurational entropy. We find that the kinetic fragility increases with increasing softness of the potential, consistent with previous results for these model systems, but at variance with the thermodynamic fragility, which decreases with increasing softness of the interactions, as well as expectations from earlier results. We rationalize our results by considering the full form of the Adam-Gibbs relation, which requires, in addition to the temperature dependence of the configurational entropy, knowledge of the high temperature activation energies in order to determine fragility. We show that consideration of the scaling of the high temperature activation energy with the liquid density, analyzed in recent studies, provides a partial rationalization of the observed behavior.     

Polyaniline nanostructures expedient as working electrode materials in supercapacitors

Granular type polyaniline (PANi), PANi nanofibers (NFs), and PANi nanotubes (NTs) expedient as working electrode materials for supercapacitors are synthesized. The synthesis procedure used in this work facilitates not only the synthesis of solid powders of the PANi nanostructures, but also thin films constituted by the same PANi nanostructures in the same experiment. PANi NFs are found to exhibit faster electrode kinetics and better capacitance when compared to PANi NTs and granular PANi. Specific capacitance and energy storage per unit mass of PANi NFs are 239.47 Fg^?1 (at 0.5 Ag^?1) and 43.2 Wh?kg^?1, respectively. Electrical conductivity of PANi NFs is also better when compared to the other two nanostructures. Properties of the three PANi nanostructures are explicated in correlation with crystallinity, intrinsic oxidation state, doping degree, BET surface area, and ordered mesoporosity pertaining to the nanostructures.     

On the solutions of a singular elliptic equation concentrating on two orthogonal spheres

Let \({A=\{x\in \mathbb{R}^{2m}: 0 < a < |x| < b\}}\) be an annulus. We consider the following singularly perturbed elliptic problem on A $$\left\{\begin{array}{lll}-\varepsilon ^2{\Delta u} + |x|^{\eta}u =|x|^{\eta}u^p, \quad {\rm in} A,\\ u > 0, \quad \quad \quad \quad \quad \quad \quad {\rm in} A, \\ u=0, \quad \quad \quad \quad \quad \quad \quad {\rm on}\partial A,\end{array}\right. $$ where \({1 < p < \frac{m+3}{m-1}}\) . We shall prove the existence of a positive solution \({u_\epsilon }\) which concentrates on two different orthogonal spheres of dimension (m?1) as \({\varepsilon \to 0}\) . We achieve this by studying a reduced problem on an annular domain in \({\mathbb{R}^{m+1}}\) and analysing the profile of a two point concentrating solution in this domain.     

Probing Distance‐Dependent Plasmon‐Enhanced Near‐Infrared Fluorescence Using Polyelectrolyte Multilayers as Dielectric Spacers

Owing to their applications in biodetection and molecular bioimaging, near‐infrared (NIR) fluorescent dyes are being extensively investigated. Most of the existing NIR dyes exhibit poor quantum yield, which hinders their translation to preclinical and clinical settings. Plasmonic nanostructures are known to act as tiny antennae for efficiently focusing the electromagnetic field into nanoscale volumes. The fluorescence emission from NIR dyes can be enhanced by more than thousand times by precisely placing them in proximity to gold nanorods. We have employed polyelectrolyte multilayers fabricated using layer‐by‐layer assembly as dielectric spacers for precisely tuning the distance between gold nanorods and NIR dyes. The aspect ratio of the gold nanorods was tuned to match the longitudinal localized surface plasmon resonance wavelength with the absorption maximum of the NIR dye to maximize the plasmonically enhanced fluorescence. The design criteria derived from this study lays the groundwork for ultrabright fluorescence bullets for in vitro and in vivo molecular bioimaging.     

Synthesis of optically pure 2,3,4-trisubstituted tetrahydrofurans via a two-step sequential Michael-Evans aldol cyclization strategy: total synthesis of (+)-magnolone

Synthesis of optically pure 2,3,4-trisubstituted tetrahydrofurans is described employing a two-step Michael-Evans aldol cyclization strategy. The approach is successfully applied for the total synthesis of furano lignan natural product (+)-magnolone.     

Triggered Release of an Active Peptide Conjugate from a DNA Device by an Orally Administrable Small Molecule

A real tonic : In a conceptually new approach to controlled release, the natural daily insulin profile in response to three meals is mimicked (see graph) with release of an insulin conjugate from a matrix, triggered by quinine, a component of tonic water.

     

Amphiphilic Multi‐Arm Block Copolymer Based on Hyperbranched Polyester,Poly(L‐lactide) and Poly(ethylene glycol) as a Drug Delivery Carrier

A novel type of biodegradable/biocompatible amphiphilic hyperbranched copolymer (H40‐PLA‐b‐MPEG) was synthesized. Its micellar properties were studied by DLS, fluorescence spectroscopy and TEM. The drug release profile showed that the H40‐PLA‐b‐MPEG micelles provide an initial burst release, followed by a sustained release of the entrapped hydrophobic model drug over a period of 4 to 58 h. The copolymer degraded hydrolytically within 6 weeks under physiological conditions. The MTT assay showed no obvious cytotoxicity against a human endothelial cell line at a concentration range of 0–400 µg · mL⁻¹. These results indicate that the H40‐PLA‐b‐MPEG micelles have great potential as hydrophobic drug delivery carriers.

     

In Silico Molecular Docking Analysis of Karanjin against Alzheimer’s and Parkinson’s Diseases as a Potential Natural Lead Molecule for New Drug Design,Development and Therapy

Parkinson’s disease (PD) and Alzheimer’s disease (AD) are neurodegenerative disorders that have emerged as among the serious health problems of the 21st century. The medications currently available to treat AD and PD have limited efficacy and are associated with side effects. Natural products are one of the most vital and conservative sources of medicines for treating neurological problems. Karanjin is a furanoflavonoid, isolated mainly from Pongamia pinnata with several medicinal plants, and has been reported for numerous health benefits. However, the effect of karanjin on AD and PD has not yet been systematically investigated. To evaluate the neuroprotective effect of karanjin, extensive in silico studies starting with molecular docking against five putative targets for AD and four targets for PD were conducted. The findings were compared with three standard drugs using Auto Dock 4.1 and Molegro Virtual Docker software. Additionally, the physiochemical properties (Lipinski rule of five), drug-likeness and parameters including absorption, distribution, metabolism, elimination and toxicity (ADMET) profiles of karanjin were also studied. The molecular dynamics (MD) simulations were performed with two selective karanjin docking complexes to analyze the dynamic behaviors and binding free energy at 100 ns time scale. In addition, frontier molecular orbitals (FMOs) and density-functional theory (DFT) were also investigated from computational quantum mechanism perspectives using the Avogadro-ORCA 1.2.0 platform. Karanjin complies with all five of Lipinski’s drug-likeness rules with suitable ADMET profiles for therapeutic use. The docking scores (kcal/mol) showed comparatively higher potency against AD and PD associated targets than currently used standard drugs. Overall, the potential binding affinity from molecular docking, static thermodynamics feature from MD-simulation and other multiparametric drug-ability profiles suggest that karanjin could be considered as a suitable therapeutic lead for AD and PD treatment. Furthermore, the present results were strongly correlated with the earlier study on karanjin in an Alzheimer’s animal model. However, necessary in vivo studies, clinical trials, bioavailability, permeability and safe dose administration, etc. must be required to use karanjin as a potential drug against AD and PD treatment, where the in silico results are more helpful to accelerate the drug development.     

Stereodivergent Transformation of Azepino[3,4,5-cd]indoles En Route to Nature-Inspired Scaffolds

Azepino[3,4,5-cd]indole derivatives represent the core scaffold of important natural products and biologically relevant compounds. Therefore, the establishment of step- and atom-economic strategies to access this class of compounds is of paramount importance. To this end, complexity-to-diversity (CtD) strategy has become one of the most important tools that transforms complex molecules into diverse skeleta. However, many of the reactions that could be employed in CtD are restricted by the functional handles exist in these molecules. This limits the achievement of the desired skeletal diversity. Herein, an efficient and step-economic strategy to access a diverse collection of azepino-[3,4,5-cd]indole architectures through a cascade that combines Pictet-Spengler with Michael addition, is described. This was achieved by reacting cyclohexadienone acetaldehydes 2 a – 2 d with indolyl-4-ethyl amine 1 . Employing a CtD strategy on the developed azepino-[3,4,5-cd]indoles, a rapid rearrangement reaction that provided a modular, chemo- and diastereoselective access to diverse collection of spiro azepinocarbazole nature-inspired frameworks, was encountered.