A Conformational Mimetic Approach for the Synthesis of Carbocyclic Nucleosides as Anti‐HCV Leads

Computer‐aided approaches coupled with medicinal chemistry were used to explore novel carbocyclic nucleosides as potential anti‐hepatitis C virus (HCV) agents. Conformational analyses were carried out on 6‐amino‐1H‐pyrazolo[3,4‐d]pyrimidine (6‐APP)‐based carbocyclic nucleoside analogues, which were considered as nucleoside mimetics to act as HCV RNA‐dependent RNA polymerase (RdRp) inhibitors. Structural insight gained from the modeling studies revealed the molecular basis behind these nucleoside mimetics. The rationally chosen 6‐APP analogues were prepared and evaluated for anti‐HCV activity. RdRp SiteMap analysis revealed the presence of a hydrophobic cavity near C7 of the nucleosides; introduction of bulkier substituents at this position enhanced their activity. Herein we report the identification of an iodinated compound with an EC₅₀ value of 6.6 μM as a preliminary anti‐HCV lead.     

Charge conduction process and photoelectrical properties of Schottky barrier device based on sulphonated nickel phthalocyanine

In this paper, the optical and electrochemical properties of sulphonated nickel phthalocyanine (NiPcS_mix) were investigated. The ground state of spectra of NiPcS_mix show splitting of Q band in DMF, but the fluorescence spectra have only one band, suggesting that only some component of the sulphonated NiPc fluoresce. Since, the organic materials are described on the basis of molecular orbital energies, i.e. highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) instead of valence band and conduction band. Such energies were estimated from cyclic voltammetry and optical absorption measurements. The dark current–voltage characteristics of ITO/NiPcS_mix/Ag device in dark at room temperature shows a rectification behavior. At low voltages, current in forward direction was found to obey the diode equation, i.e. exponential increase in current with applied voltage and the conduction was controlled by thermionic emission mechanism. For relatively higher voltages, the conduction was dominated by a space charge limited conduction mechanism with single trap level of 0.34 eV. The J–V characteristics in dark and the comparison of photoaction spectra of the device with the optical absorption spectra of NiPcS_mix indicates the formation of Schottky barrier and Ohmic contact at Ag-NiPcS_mix and ITO-NiPcS_mix, respectively, in ITO/NiPcS_mix/Ag device. The junction parameters such as built in potential, potential barrier height, carrier concentration and width of depletion layer were estimated from the capacitance–voltage (C–V) measurement. The J–V characteristic under illumination shows photovoltaic effect. The power conversion efficiency of the device has been improved upon thermal annealing attributed to the enhancement in the both crystallinity of NiPcS_mix and charge carrier mobility due to the thermal treatment. We have also investigated the effect of PEDOT:PSS buffer layer in between ITO and NiPcS_mix on electrical and photovoltaic properties of the device.     

Electrochemical behavior of nanocrystalline Ni–P alloys containing tin and tungsten

Autocatalytic ternary Ni-Sn-P, Ni-W-P and quaternary Ni-W-Sn-P films were prepared using an alkaline bath. Plain Ni-P films were also prepared for comparison. Corrosion resistance of the films was evaluated in 3.5% sodium chloride solution in non-deaerated condition by potentiodynamic polarization and electrochemical impedance spectroscopy methods. Deposits were also immersed in 3.5% sodium chloride solution for 7 days. All the coatings attained stable equilibrium potential within 30 minutes in NaCl medium. Lower corrosion current density values were obtained for ternary Ni-Sn-P coatings compared to the plain Ni-P coatings. Ternary Ni-W-P and quaternary Ni-W-Sn-P alloys did not show improved corrosion resistance compared to the ternary Ni-Sn-P coatings. Similar behavior of these coatings was further confirmed by the electrochemical impedance studies. After the potentiodynamic polarization test deposits were examined by scanning electron microscope. It was found that more corrosion occurred for the quaternary deposit compared to other deposits. Energy dispersive analysis of X-ray results indicated that more amount of Fe present on NiWP and NiWSnP coated samples. Similar behavior was confirmed from the optical images of the surfaces obtained for the deposits after the immersion test. The article is published in the original.     

Effect of Mn/Mo incorporated oxide layer on the corrosion behavior of AA 2024 alloy

The oxide layer formed over AA 2024 using 10 wt.% H₂SO₄ (plain oxide, PO) was modified by Mn/Mo oxyanions (permanganate/molybdate modified oxide, PMMO) as an alternative to Cr(VI) ions to enhance the corrosion resistance. The corrosion current density values obtained for PMMO was found to be 2.8% and 1.4% of hydrothermal treated oxide (HTO) and PO respectively after 168 h immersion in 3.5% NaCl solution. The electrochemical studies showed the higher barrier layer resistance for PMMO. The improved corrosion behavior of PMMO was observed based on the damage function calculated. Similar observations were confirmed by continuous salt spray test.     

Electroless Ni–P composite coatings

This review outlines the development of electroless Ni–P composite coatings. It highlights the method of formation, mechanism of particle incorporation, factors influencing particle incorporation, effect of particle incorporation on the structure, hardness, friction, wear and abrasion resistance, corrosion resistance, high temperature oxidation resistance of electroless Ni–P composite coatings as well as their applications. The improvement in surface properties offered by such composite coatings will have a significant impact on numerous industrial applications and in the future they will secure a more prominent place in the surface engineering of metals and alloys.     

Hardness and wear behaviour of electroless Ni–B coatings

Depth-dependent hardness variation of dimethylamine borane-reduced electroless Ni–5?wt-%B deposits has been examined using the nanoindentation technique. The deposits were characterised using ICP-OES, FESEM, XRD and DSC for evaluating the composition, morphology, structure and phase transformation behaviour, respectively. Coatings were also analysed for hardness and wear resistance. The surface of the as-plated deposit exhibits a typical nodular morphology. DSC traces show the presence of a single exothermic peak at 313°C conforming to its phase transformation. X-ray diffraction pattern of as-prepared deposit contains a mixture of amorphous and sharp microcrystalline nickel peaks. Heat-treated coating exhibits improved hardness and wear resistance. Depth-dependent nanohardness profile of as-deposited film neither obeys Nix–Gao nor the Lam–Chong model of indentation.     

Synthesis and Characterization of Zirconia Supported Vanadium Incorporated Ammonium Salt of 12-molybdophosphoric Acid Catalyst for Aerobic Oxidation of Benzyl alcohol

A series of zirconia supported ammonium salt of molybdophosphoric acid (AMPV) catalysts with and with out vanadium incorporation are prepared in a single step adopting wet impregnation method. These catalysts are characterized by BET surface area, XRD, FT-IR and potentiometric titration. XRD and FT-IR techniques suggest the formation of Keggin ion on zirconia support. The high resolution FT-IR analysis reveals the incorporation of vanadium into the primary structure of Keggin ion. The catalytic functionalities of these catalysts are tested for the aerobic oxidation of benzyl alcohol. The vanadium containing AMPV results in higher selectivity towards the oxidation product compared to the catalyst without vanadium incorporation.     

Comparison in the Oxidation and Corrosion Behavior of Aluminum and Alumina-Reinforced Ni/Ni-Co Alloy Coatings

In this study, a comparison in the oxidation and corrosion behavior of Ni/Ni-Co aluminum and alumina-reinforced electrodeposited composites has been made. The developed coatings were characterized for the morphology, structure, microhardness, oxidation, and corrosion resistance. It was found that the incorporation of Al particles in NiCo matrix is higher (9 wt pct) compared to Ni matrix (1 wt pct). In the case of aluminum oxide particles, about 5 and 7 wt pct had been obtained in Ni and NiCo matrices respectively. The difference in the surface morphology was observed with respect to metallic (Al) and inert ceramic (Al₂O₃) particle incorporation. X-ray diffraction studies showed the presence of predominant Ni (200) reflection in the coatings. Also, peaks corresponding to Al and Al₂O₃ particles were present. The Ni/NiCo-Al coatings exhibited higher microhardness values at 1273 K (1000 °C) compared to alumina-reinforced coatings, indicating better thermal stability of the former coatings. The NiAl coating showed one and two orders of magnitude improved oxidation resistance compared to NiCoAl and Ni/NiCo-Al₂O₃ coatings, respectively. It was observed that the Ni-Al composite coating exhibited poor corrosion resistance in 3.5 pct NaCl solution compared to the other coatings studied.     

Hydrogenolysis of N-Benzylcyclohexylamine: A Support Specific ‘Nano Effect’

Catalysis Letters - The hydrogenolysis of N-benzylcyclohexylamine (NBCA) was carried out at low temperature and pressure using series of Pd/SiO2 catalysts having Pd contents between 0.5 and 10%....     

Electroless ternary Ni-W-P alloys containing micron size Al2O3 particles

In the present investigation electroless ternary NiWP-Al₂O₃ composite coatings were prepared using an electroless nickel bath. Second phase alumina particles (1 µm) were used to codeposit in the NiWP matrix. Nanocrystalline ternary NiWP alloys and composite coatings were obtained using an alkaline citrate based bath which was operated at pH 9 and temperature at 88 ± 2 °C. Mild steel was used as a substrate material and deposition was carried out for about 4 h to get a coating thickness of 25 ± 3 µm. Metallographic cross-sections were prepared to find out the coating thickness and also the uniform distribution of the aluminum oxide particles in NiWP matrix. Surface analysis carried out on both the coatings using scanning electron microscope (SEM) showed that particle incorporation in ternary NiWP matrix has increased the nodularity of composite coatings compared to fine nodular NiWP deposits. Elemental analysis of energy dispersive X-ray (EDX) results showed that codeposited P and W elements in plain NiWP deposit were 13 and 1.2 wt.%, respectively. There was a decrease in P content from 13 to 10 wt.% with a marginal variation in the incorporated W (1.01 wt.%) due to the codeposition of aluminum oxide particles in NiWP matrix. X-ray diffraction (XRD) studies carried out on as-plated deposits showed that both the deposits are X-ray amorphous with a grain size of around 3 nm. Phase transformation studies carried out on both the coatings showed that composite coatings exhibited better thermal stability compared to plain NiWP deposits. From the XRD studies it was found that metastable phases such as NiP and Ni₅P₂ present in the composite coatings heat treated at major exothermic peak temperature. Annealed composite coatings at various temperatures revealed higher microhardness values compared to plain NiWP deposits.