Hydrogen evolution reaction and formic acid oxidation by decorated nanostructural Pt/Pd on a copper-filled nanoporous stainless steel

In this work, a 304 stainless steel (SS) was anodized to prepare nanoporous SS (NPSS) with an average size of about 75 nm and then filled with copper (Cu/NPSS) using pulsed electrodeposition method. Afterward, a nanostructural Pt and Pd film was deposited by galvanic replacement (GR) on the Cu/NPSS to prepare modified electrode (PtPd/Cu/NPSS) for hydrogen evolution reaction (HER) and formic acid electrooxidation (FAO). The electrocatalytic activity of the modified electrode and its structural characterization have been studied by voltammetric methods, electrochemical impedance spectroscopy (EIS), inductively coupled plasma optical emission spectrometry (ICP-OES), and field emission scanning electron microscopy (FESEM). The results show that the nanostructural Pt₁Pd₁/Cu/NPSS composition, with low Pt loading and suitable stability, has a good electrocatalytic performance toward HER (E_Onset = + 12 mV vs. NHE) and FAO (E_Onset = ?180 mV vs. NHE). For HER observed a high mass activity of noble metals (87.54 mA cm^?2μg _Pd+Pt ^?1 ) in comparison with Pt deposited Cu/NPSS (41.5 mA cm^?2 μg _Pt ^?1 ) at the same applied potential of ? 0.25 V versus NHE. Also, the fabricated electrocatalysts with more electrochemically active surface area in comparison with Pd/Cu/NPSS and Pt/Cu/NPSS revealed more resisting to the poisoning components and good stability for FAO.     

Nuclear charge distributions from 4π-β measurements on mass separated fragments from235U(nth,f)

A 4- detector was used at the Lohengrin mass separator to measure the-activity of mass chains 91, 93, 94, 95, 137 and 139 produced in the thermal neutron induced fission of²³⁵U. This activity was analysed intoZ-yields. The different possible corrections were considered and applied to the data. TheZ-yields from this work are compared with the diverse existing results obtained with other methods. The need for and significance of this method to determine theZ-distribution of fission fragments of the heavy group is discussed.     

Synthesis of C59Hx and C58Hx fullerenes stabilized by hydrogen

Prolonged hydrogenation of C(60) molecules by reaction with H(2) at elevated temperature and pressure results in fragmentation and collapse of the fullerene cage structure. However, fragments can be preserved by immediate termination of dangling bonds by hydrogen. Here we demonstrate that not only fullerene fragments but also hydrogenated fragmented fullerenes (e.g., C(58)H(40) and C(59)H(40)) can be synthesized in bulk amount by high-temperature hydrogenation of C(60). We confirm successful synthesis of these species by matrix-assisted laser desorption ionization time-of-flight mass spectrometry and complete speciation of the resultant complex fullerene mixtures by high-resolution field desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry.     

Conformation analyses, dynamic behavior, and amide bond distortions of medium-sized heterocycles. 2. Partially and fully reduced 1-benzazocines, benzazonines, and benzazecines

Partially and fully reduced forms of benzo-fused eight- to ten-membered nitrogen heterocycles (1-benzazecines, 1-benzazonines and 1-benzazecines) have been prepared. Conformational features, transannular distances and dynamic behavior were studied using X-ray crystallography and VT NMR spectroscopy. The amide moiety in the nine-membered benzazonine ring 5b favors N-pyramidization, whereas the ten-membered benzazecine 5c adopts an amide twist. Molecular mechanics calculations reveals a correlation between the amide twist (tau) and ring stability. The dynamic behavior of the heterocycles in solution were also found to be dependent on the extent and nature of the amide distortion. We thus conclude that ring strain of these medium-sized heterocyclic rings is relieved through amide distortion, which leads to a more stable structure.     

Axisymmetric stagnation flow obliquely impinging on a moving circular cylinder with uniform transpiration

Laminar stagnation flow, axisymmetrically yet obliquely impinging on a moving circular cylinder, is formulated as an exact solution of the Navier–Stokes equations. Axial velocity is time‐dependent, whereas the surface transpiration is uniform and steady. The impinging free stream is steady with a strain rate k?. The governing parameters are the stagnation‐flow Reynolds number Re=k?a²/2ν, and the dimensionless transpiration S=U₀/k?a. An exact solution is obtained by reducing the Navier–Stokes equations to a system of differential equations governed by Reynolds number and the dimensionless wall transpiration rate, S. The system of Boundary Value Problems is then solved by the shooting method and by deploying a finite difference scheme as a semi‐similar solution. The results are presented for velocity similarity functions, axial shear stress and stream functions for a variety of cases. Shear stresses in all cases increase with the increase in Reynolds number and suction rate. The effect of different parameters on the deflection of viscous stagnation circle is also determined. Copyright © 2010 John Wiley & Sons, Ltd.     

A validated,rapid and cost-efficient HPTLC method for the quantification of plumbagin and its antioxidant activity from the different extracts of Plumbago zeylanica L.

JPC – Journal of Planar Chromatography – Modern TLC - In the present work, a simple, rapid, reliable and accessible high-performance thin-layer chromatography (HPTLC) technique has been...     

GC–MS analysis of phytoconstituents present in methanolic extract of Actinidia deliciosa L. fruits and its antioxidant activity

Kiwi fruit (KF) (Actinidia deliciosa L.) are members of the Actinidia genus (Family Actinidiaceae). Previously these plants have confirm anti-diabetic, anti-oxidant, anti-inflammatory, antifungal, anticarcinogenic, hepatoprotective, anti-microbial etc. properties. The therapeutic efficacy of complex phytoconstituents found in fruit extracts has piqued the interest of pharmaceutical companies and academics alike. Methanolic extract of kiwi fruit (MEKF) was analyzed by gas chromatography-mass spectroscopy and yielded positive results signaling towards identification and characterization of therapeutic claims of this species in the traditional system. The antioxidant activity of MEKF was determined by the most suitable DPPH method. The most significant constituents found in MEKF are 2-cyclohexylpiperidine (0.58%), phenol, 2,4-bis(1,1-dimethylethyl)- (0.13%), 1,6-anhydro- β-d-glucopyranose (0.52%), dodecanoic acid (0.32%), 2-heptenoic acid, trimethylsilyl ester (2.84%), Tetradecanoic acid (1.87%), Neophytadiene (2.81%), Hexahydro farnesyl acetone (1.72%), Neophytadiene (0.97%), n-hexadecanoic acid (19.00%), Ethyl hexadecanoate (7.21%), Linoleic acid ethyl ester (0.23%), Phytol (4.74%), α-linolenic acid (16.73%), Ethyl (9z,12z)-9,12-octadecadienoate (2.92%), Octadecanoic acid (4.76%), Octadecanoic acid, 17-methyl-, methyl ester (1.68%), Phytol, acetate (0.15%), 2-Methylhexacosane (0.97%), Ethyl 9,12,15-octadecatrienoate (0.81%), Tetracontane (1.45%), α-tocospiro A (0.15%), α-tocospiro B (0.19%), 3.β-Acetoxystigmasta-4,6,22-triene (0.24%), Octacosane, 1-iodo (0.43%), 4,6-cholestadien-3.β-ol, benzoate (2.14%), γ.-Sitosterol (4.40%), and Tigogenin (2.32%). The found results in the analysis of the antioxidant activity of MEKF showed significant free radical scavenging capacity against DPPH-generated free radicals due to the presence of alkaloids, glycoside, terpenoids, vitamins, and some other reported compounds. In the pharmaceutical industry, GC-MS reports will be useful for identifying a wide range of phytoconstituents in polyherbal extracts and standardizing of plant materials.