Synthesis,characterization, and thin‐film properties of 6‐oxoverdazyl polymers prepared by ring‐opening metathesis polymerization

Redox‐active 6‐oxoverdazyl polymers were synthesized via ring‐opening metathesis polymerization (ROMP) and their solution, bulk, and thin‐film properties investigated. Detailed studies of the ROMP method employed confirmed that stable radical polymers with controlled molecular weights and narrow molecular weight distributions (Ð < 1.2) were produced. Thermal gravimetric analysis of a representative example of the title polymers demonstrated stability up to 190 °C, while differential scanning calorimetry studies revealed a glass transition temperature of 152 °C. Comparison of the spectra of 6‐oxoverdazyl monomer 12 and polymer 13 , including FT‐IR, UV‐vis absorption, and electron paramagnetic resonance spectroscopy, was used to confirm the tolerance of the ROMP mechanism for the 6‐oxoverdazyl radical both qualitatively and quantitatively. Cyclic voltammetry studies demonstrated the ambipolar redox properties of polymer 13 (E_1/2,ox = 0.25 and E_1/2,red = ?1.35 V relative to ferrocene/ferrocenium), which were consistent with those of monomer 12 . The charge transport properties of thin films of polymer 13 were studied before and after a potential of 5 V was applied, revealing a drastic drop in the resistivity from 10⁶?10¹⁰ Ω m or more to 1.7 × 10⁴ Ω m and suggesting the potential usefulness of polymer 13 in bistable electronics. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1803–1813     

Preparation of multi metal–carbon nanoreactors for adsorption and catalysis

Metal–incorporated composite carbon materials have engendered great progress in the fields of catalysis, energy storage and material science because of their size and chemical and physical properties. In this study, a modern technique was applied for the development of multi metal–carbon nanoreactors (MCNRs) from a pristine carbon cage (CC) using template method with nano silica ball (NSB), pyrolysis fuel oil (PFO) and metal nanocrystals such as gold, copper, nickel, potassium and manganese. The newly prepared Au, Cu, Ni, K and Mn deposited carbon nanoreactors were fully characterized by various analytical techniques. Due to their easy fabrication protocols and broad potential applications, the MCNRs were used successfully for the chemisorptions of hydrogen and ethylene gases alongside the solvent–free heterogeneous catalytic oxidation of a secondary alcohol. The MCNRs have exhibited dynamic adsorption performance and excellent catalytic activity.     

A Novel Framework for Integration of Random-Walk Particle-Tracking Simulation in Subsurface Multi-phase Flow Modeling

Coarse-scale models are generally preferred in the numerical simulation of multi-phase flow due to computational constraints. However, capturing the effects of fine-scale heterogeneity on flow and isolating the impacts of numerical (artificial) dispersion, which increases with scale, are not trivial. In this paper, a particle-tracking method is devised and integrated in a scale-up workflow to estimate the conditional probability distributions of multi-phase flow functions, which can be considered as inputs in coarse-scale simulations with existing commercial packages. First, a novel particle-tracking method is developed to solve the saturation transport equation. The transport calculation is coupled with a velocity update, following the implicit pressure, explicit saturation framework, to solve the governing equations of two-phase immiscible flow. Each phase particle is advanced in a deterministic convection step according to the phase velocity, as well as in a stochastic dispersion step based on the random Brownian motion. A kernel-based formulation is proposed for computation of fluid saturation in accordance with the phase particle distribution. A novel aspect is that this method employs the kernel approach to construct saturation from phase particle distribution, which is an important improvement to the conventional box method that necessitates a large number of particles per grid cell for consistent saturation interpolation. The model is validated against various analytical solutions. Finally, the validated model is integrated in a statistical scale-up procedure to calibrate effective, or “pseudo,” multi-phase flow functions (e.g., relative permeability functions). The proposed scale-up framework does not impose any length scale requirement regarding the distribution of sub-grid heterogeneities.     

Fission studies in the reaction of <Superscript>19</Superscript>F with <Superscript>209</Superscript>Bi at 99.2 MeV

Fission product yield studies in the reaction of 99.2 MeV ¹⁹F with ²⁰⁹Bi have been carried out for the first time using gamma-ray spectrometry. The cross sections for the production of fission products have been determined. The yield distribution of fission products was found to be symmetric and broad with FWHM around 22 mass units and peak near mass 111. The average number of neutrons emitted per fission has been found to be around 6.7. The comparison of the fission products yield distribution of ²⁰⁹Bi using projectiles like ⁴He, ¹²C, ¹⁶O, and ¹⁹F have shown that the mass of symmetric peak increases as the mass of the compound nucleus increases. The high fission yield around mass 112 has been attributed to the presence of deformed neutron shells. The total fission cross section and width of the mass distribution have been found to be low in case of ¹⁶O induced fission as compared to the ⁴He, ¹²C, and ¹⁹F induced fission of ²⁰⁹Bi.     

Development of predictive pharmacophore model for in silico screening,and 3D QSAR CoMFA and CoMSIA studies for lead optimization,for designing of potent tumor necrosis factor alpha converting enzyme inhibitors

A chemical feature-based pharmacophore model was developed for Tumor Necrosis Factor-α converting enzyme (TACE) inhibitors. A five point pharmacophore model having two hydrogen bond acceptors (A), one hydrogen bond donor (D) and two aromatic rings (R) with discrete geometries as pharmacophoric features was developed. The pharmacophore model so generated was then utilized for in silico screening of a database. The pharmacophore model so developed was validated by using four compounds having proven TACE inhibitory activity which were grafted into the database. These compounds mapped well onto the five listed pharmacophoric features. This validated pharmacophore model was also used for alignment of molecules in CoMFA and CoMSIA analysis. The contour maps of the CoMFA/CoMSIA models were utilized to provide structural insight for activity improvement of potential novel TACE inhibitors. The pharmacophore model so developed could be used for in silico screening of any commercial/in house database for identification of TACE inhibiting lead compounds, and the leads so identified could be optimized using the developed CoMSIA model. The present work highlights the tremendous potential of the two mutually complementary ligand-based drug designing techniques (i.e. pharmacophore mapping and 3D-QSAR analysis) using TACE inhibitors as prototype biologically active molecules.     

Direct transfer of micro-molded electrodes for enhanced mass transport and water management in PEMFC

Soft lithography technique is used to micropattern the electrodes on the electrolyte membrane of polymer electrolyte fuel cell (PEMFC) in order to alleviate the issues due to poor water management and inadequate reactant distribution in the fuel cell environment. Membrane electrode assembly with the micropatterned electrode has shown an increase in power density at a higher temperature as well as at a higher relative humidity when compared to a flat electrode. Consistency in cell performance is observed in the case of micropatterned electrodes.     

Challenges to radio over fiber (RoF) technology and its mitigation schemes – A review

For realization of future high performance integrated networks, broadband distribution and access networks and to meet the increasing demand of multimedia services with a guaranteed quality of service, RoF technology comes out as the most promising technology that combines the capacity of optical networks with the flexibility and mobility of wireless networks. Reduction in complexity at the antenna site, reduction in installation cost of access networks, possibility of dynamically allocation of radio carriers to different antenna sites, transparency and scalability are the few advantages of radio-over-fiber (RoF) technology. In this paper, we review the different challenges that limit the probable capabilities of RoF communication networks and different mitigation techniques to combat with these challenges to realize high-performance RoF links.     

Ruthenium‐catalyzed biginelli condensation: A simple and efficient one‐pot synthesis of 3,4‐dihydropyrimidin‐2(1H)‐ones under mild reaction conditions

Ruthenium trichloride was found to be an efficient catalyst for the first time for the synthesis of a variety of 3,4‐dihydropyrimidin‐2(1H)‐ones by cyclocondensation of an aldehyde, β‐dicarbonyl compound and urea in excellent yields under mild reaction conditions.     

Modular alpha-helical mimetics with antiviral activity against respiratory syncitial virus

A 13-residue peptide sequence from a respiratory syncitial virus fusion protein was constrained in an alpha-helical conformation by fusing two back-to-back cyclic alpha-turn mimetics. The resulting peptide, Ac-(3-->7; 8-->12)-bicyclo-FP[KDEFD][KSIRD]V-NH(2), was highly alpha-helical in water by CD and NMR spectroscopy, correctly positioning crucial binding residues (F488, I491, V493) on one face of the helix and side chain-side chain linkers on a noninteracting face of the helix. This compound displayed potent activity in both a recombinant fusion assay and an RSV antiviral assay (IC(50) = 36 nM) and demonstrates for the first time that back-to-back modular alpha-helix mimetics can produce functional antagonists of important protein-protein interactions.