Determination of indium in high purity antimony by electrothermal atomic absorption spectrometry (ETAAS) using boric acid as a modifier

The use of boric acid as a modifier for the determination of trace amount of indium in high purity antimony by electrothermal atomic absorption is described. It was found that the negative influence of the hydrofluoric acid, used for the digestion could not be eliminated by using stabilized temperature platform furnace (STPF) alone. Due to the high dissociation energy (D₀ = 506 kJ mol⁻¹) of indium fluoride, it is difficult to dissociate in the gas phase and hence is lost. In presence of HF (used for the dissolution of antimony), the universal Pd-Mg modifier does not work satisfactorily. Additionally, rising corrosion and reduced tube lifetime were observed when the acid digested (HF-HNO₃) antimony solution was injected in to the platform. Improvement in platform life and elimination of interferences were achieved by the addition of boric acid as a chemical modifier together with ruthenium coating of the platform. Corrosive changes of the transversely heated graphite atomizer (THGA) platform surface were examined by scanning electron microscopy. The standard addition method was applied. A characteristic mass of 36 pg was obtained. The detection limit of the proposed method is around 0.04 μg g⁻¹. The developed method was applied to the determination of indium in real samples. The data obtained by this method were in good agreement with those obtained by ICP-MS.     

Synthesis,CMC determination and influence of the micelles, β-cyclodextrin,ionic liquids and liposome(dipalmitoylphosphatidylcholine) vesicles on the kinetics of an outer-sphere electron transfer reaction

The surfactant–cobalt(III) complex, cis-[Co(trien)(4AMP)(DA)](ClO₄)₃, trien = triethylenetetramine, 4AMP = 4-aminopyridine, DA = dodecylamine was synthesized and characterized by various spectroscopic and physico-chemical techniques. The critical micelle concentration (CMC) value of this surfactant–cobalt(III) complex in aqueous solution was found out from conductance measurements. The conductivity data (at 303, 308, 313, 318 and 323 K) were used for the evaluation of the temperature-dependent CMC and the thermodynamics of micellization (ΔG _m ^° , ΔH_m and ΔS _m ^° ). Also the kinetics of reduction of this surfactant–cobalt(III) complex by hexacyanoferrate(II) ion in micelles, β-cyclodextrin, ionic liquids (ILs) and in liposome vesicles (DPPC) media were studied at different temperature. The rate constant for the electron transfer reaction in micelles was found to increase with increase in the initial concentration of the surfactant–cobalt(III) complex. This peculiar behaviour of dependence of second-order rate constant on the initial concentration of one of the reactants has been attributed to the presence of various concentration of micelles under different initial concentration of the surfactant–cobalt(III) complex in the reaction medium. Inclusion of the long aliphatic chain of the surfactant complex ion into β-cyclodextrin leads to decrease in the rate constant. Below the phase transition temperature of DPPC, the rate decreased with increasing concentration of DPPC, while above the phase transition temperature the rate increased with increasing concentration of DPPC. It is concluded that below the phase transition temperature, there is an accumulation of surfactant–cobalt(III) complex at the interior of the vesicle membrane through hydrophobic effects, and above the phase transition temperature the surfactant–cobalt(III) complex is released from the interior to the exterior surface of the vesicle. In the presence of ionic liquid medium the second order rate constant for this electron transfer reaction for the same complex was found to increase with increasing concentration of ILs has also been studied. An outer-sphere mechanism is proposed for all these reactions and the results have been explained based on the hydrophobicity of the ligand and the reactants with opposite charges.     

Synthesis,characterisation, and electrical properties of novel nanostructured conducting poly(aniline-<Emphasis Type="Italic">co</Emphasis>-<Emphasis Type="Italic">m</Emphasis>-chloroaniline) with incorporated silver particles

Novel copolymers of poly(aniline-co-m-chloroaniline)-doped dodecylbenzenesulphonic acid (DBSA) with embedded silver nanoparticles were synthesised using the in situ chemical oxidative method. The structural properties of the copolymers were characterised using the UV-VIS and FTIR spectroscopic methods. The crystalline nature of the copolymer was demonstrated by way of the X-ray diffraction (XRD) pattern. Scanning electron microscopy (SEM) revealed the presence of particle agglomerates measuring 50 nm to 100 nm on the surface of the nanocomposites. The electrical conductivity of the copolymer was dependent on the monomer composition and was found to be in the range of 10^?2 S cm^?1 to 10^?6 S cm^?1 with an increasing chloroaniline content and exhibiting improved solubility.     

Photoinduced Copper‐Catalyzed Regioselective Synthesis of Indoles: Three‐Component Coupling of Arylamines,Terminal Alkynes,and Quinones

The first successful example of a visible‐light‐induced copper‐catalyzed process for C? H annulation of arylamines with terminal alkynes and benzoquinone is described. This three‐component reaction allows use of a variety of commercial terminal alkynes as coupling partners for the one‐step regioselective synthesis of functionalized indoles. Moreover, the current process represents a sustainable and atom‐economical approach for the preparation of complex indoles from easily accessible starting materials under visible‐light irradiation, without the need for expensive metals and harsh reaction conditions.     

Time series model for GLWB with surrender benefit and stochastic interest rate: Dynamic withdrawal approach

This study investigates the pricing problem of a variable annuity (VA) contract embedded with a guaranteed lifetime withdrawal benefit (GLWB) rider. VAs are annuities in which the value is linked to a bond and equity sub-account fund. The guaranteed lifetime withdrawal benefit rider regularly provides a series of payments to the policyholder for the term of the policy while he/she is alive, regardless of portfolio performance. At the time of the policyholder's death, the remaining fund value is given to his nominee. Therefore, proper fund modeling is critical in the pricing of VA products. Several writers in the literature used a GBM model in which variance is considered to be constant to represent the fund value in a variable annuity contract. However, on the other hand, the returns on financial assets are non-normally distributed in real life. A bit much Kurtosis, leverage effect, and Non-zero Skewness characterize the returns. The generalized autoregressive conditional heteroscedastic (GARCH) models are also used for presenting a discrete framework for the pricing of GLWB. Still, the interest rate was kept constant without including the surrender benefit and the static withdrawal approach, which keeps the model far from the real scenario. Thus, in this research, the generalized GARCH models are used with surrender benefit and dynamic withdrawal strategy to develop a time series model for the pricing of annuity that overcomes the constraints of previous models. A numerical illustration and sensitivity analysis are used to examine the suggested model.     

Crystal and molecular structure of trans-bis(dodecylamine) bis(dimethylglyoximato)cobalt(III) nitrite

An octahedral geometry for the molecule of the title complex with very slight distortions around Co(III) is confirmed by single-crystal X-ray diffraction study. The molecular structure of the complex has been shown to contain two dodecylamine moieties in the trans orientations, two N-bonded dimethylglyoximato (DMG) groups and an uncoordinated nitrite ion.     

Pulsatile flow between permeable beds

Pulsatile flow of a viscous fluid between two permeable beds is analyzed. The flow between and through the permeable beds are governed by the Navier-Stokes equations and Darcy's law, respectively. The velocity field and the volume flux are obtained for several cases and discussed. Further, when the permeability parameter k→0, the results agree with those of Wang (J. Appl. Mech. 38 (1971) 553).     

High spin properties of 124Ba

The ¹²⁴Ba nucleus is investigated on the basis of the method of statistical mechanics by assuming the nucleons to move in triaxially deformed Nilsson potential. The variation in the Fermi energies of protons and neutrons is studied as a function of spin and temperature. The Fermi energies determined as a function of angular momentum is used to study the dependence of shell correction on angular momentum using the Strutinsky smoothing procedure. The most important observation is that the shell correction is almost the same for all spins for ¹²⁴Ba. The spin cutoff parameter and the single particle level density parameter are studied as a function of spin and temperature. Constant entropy lines drawn by plotting the excitation energy against angular momentum are found to be roughly at constant energy above the yrast line and are almost equally spaced. It is observed that no yrast traps are present for ¹²⁴Ba.