Photosubstitution reactions in potassium octacyanomolybdate(IV) and octacyanotungstate(IV) in the presence of 1,10-phenanthroline and 2,2-́bipyridyl

Substitution reactions take place following the photonic excitation of aqueous K₄M(CN)₈ (where M = Mo or W) in the presence of 1,10-phenanthroline and 2,2$\text{-}\text{?}$bipyridyl. Changes in absorbance with time show that the overall reaction is dependent on photochemical activation of potassium octacyanomolybdate(IV) and -tungstate(IV). The species [K₂Mo(CN)₄(OH)₂(phen)], [K₂W(CN)₄(OH)₂(phen)], [K₂Mo(CN)₄(OH)₂(bipy)] and [K₂W(CN)₄(OH)₂(bipy)] exist in solution. The final photosubstitution products [Mo(OH)₃(CN)(phen)₂] · 2H₂O], [Mo(OH)₃(CN)(bipy)₂] · 3H₂O, [W(OH)₃(CN)(phen)₂] · 2H₂O and [W(OH)₃(CN)(bipy)₂] · H₂O have been isolated in the solid state. Their IR spectra have been discussed. The quantum yield of the photosubstitution reactions has been determined and its variation with change of concentration of the complex as well as the H⁺ ion concentration has been studied.     

Effect of ionic temperature on the modulational instability of ion acoustic waves in the presence of a magnetic field

The modulational instability of ion acoustic waves is studied in the presence of a dc magnetic field, taking the ion temperature into account. It is well known that the instability sets in for wave numbers exceeding 1.47 k_D when there is no magnetic field and the ion temperature is negligible. The instability behaviour, however, changes drastically when either the magnetic field is switched on or the ion temperature becomes important or both. In general three different regions emerge wherein the waves becomes modulationally unstable. The relative sizes of these regions change as the magnetic field, the angle of propagation and the ion temperature are varied.     

Stellatic acid: a new class of sesterterpenoid; X-ray crystal structure

The complete structure of a unique tricyclic sesterterpene, stellatic acid, was established by X-ray diffraction of its p-bromophenacyl ester.     

On exact solutions for some oscillating motions of a generalized Oldroyd-B fluid

This paper deals with exact solutions for some oscillating motions of a generalized Oldroyd-B fluid. The fractional calculus approach is used in the constitutive relationship of fluid model. Analytical expressions for the velocity field and the corresponding shear stress for flows due to oscillations of an infinite flat plate as well as those induced by an oscillating pressure gradient are determined using Fourier sine and Laplace transforms. The obtained solutions are presented under integral and series forms in terms of the Mittag–Leffler functions. For α = β = 1, our solutions tend to the similar solutions for ordinary Oldroyd-B fluid. A comparison between generalized and ordinary Oldroyd-B fluids is shown by means of graphical illustrations.     

On exact solutions for some oscillating motions of a generalized Oldroyd-B fluid

This paper deals with exact solutions for some oscillating motions of a generalized Oldroyd-B fluid. The fractional calculus approach is used in the constitutive relationship of fluid model. Analytical expressions for the velocity field and the corresponding shear stress for flows due to oscillations of an infinite flat plate as well as those induced by an oscillating pressure gradient are determined using Fourier sine and Laplace transforms. The obtained solutions are presented under integral and series forms in terms of the Mittag–Leffler functions. For α = β = 1, our solutions tend to the similar solutions for ordinary Oldroyd-B fluid. A comparison between generalized and ordinary Oldroyd-B fluids is shown by means of graphical illustrations.     

Surface modification of platinum by laser-produced X-rays

Laser-induced plasma is used as an X-ray source for the growth of hillocks like nanostructures on platinum surface. To generate X-rays, plasma is produced by Nd:YAG laser, which is operated at second harmonics (λ?=?532?nm, E?=?400?mJ). Analytical grade 5?N pure Al, Cu and W are used as laser targets for X-rays production. X-rays produced from Al, Cu and W plasmas are used to irradiate three analytical grade (5?N pure) platinum substrates, respectively, under the vacuum ～10^?4 torr. XRD analysis shows considerable structural changes in the exposed platinum. The decrement in reflection intensities, increment in dislocation line density, change in d-spacing and disturbance in the periodicity of planes evidently prove these structural changes. Atomic force microscope AFM topographic analysis of the platinum exposed to X-rays emitted from Al, Cu and W targets showed that nanometer-size hillocks are produced on the platinum surface irrespective of the source. It has also been observed that due to these hillocks, the roughness of the surface has increased. Conductivity of hillocks produced from X-rays produced by Al, Cu and W targets is compared and it is shown that the hillocks produced by Al target X-rays have better conductivity compared to the hillocks produced by X-rays from Cu and W targets.     

Annealing of ion-implanted Ga0.47In0.53As

We have investigated annealing of ion-implanted GaInAs using transmission electron microscopy. We have found that the best condition for the post-implantation anneals for GalnAs is a 30 second anneal at a temperature of 700–800°C. This produces a material similar in character to the untreated GaInAs. Anneals for longer than 30 seconds produce crystal defects becoming increasingly complex with time for similar temperatures.     

Effect of ion beam irradiation on palladium (II) acetyl acetonate dispersed in polymer matrix

Composites, containing different concentrations of palladium (II) acetylacetonate in polymethyl methacrylate (PMMA) matrix were prepared by vigorous mixing. PMMA was prepared by solution polymerization technique. The composites were irradiated with a 120 MeV Ni¹⁰⁺ beam at two different fluences of 1×10¹¹ and 5×10¹² ions/cm² to study ion-induced effects on their dielectric, structural properties and surface morphology. AC electrical properties of these samples were studied in the frequency range 100 Hz to 10 MHz. The dielectric permittivity/loss shows frequency dependent behavior and it obeys the universal law of dielectric (i.e. ?α f ^n?1) for pristine and irradiated samples at high frequency. The crystalline size and crystallinity of the composites were studied by X-ray diffraction analysis. Decrease in peak intensity after irradiation signifies the amorphization which is also responsible for decrease in T _g as obtained by means of differential scanning calorimetry measurement. Fourier transform infrared spectra also support this result. Surface roughness increases upon irradiation as observed from scanning electron microscopy.