Extraction chromatographic studies of metal ions using N,N,N',N'-tetraoctyl diglycolamide as the stationary phase

N,N,N′,N′-tetraoctyl diglycolamide (TODGA) has been used as the stationary phase in the extraction chromatographic separation of actinides and other metal ions from pure nitric acid as well as from simulated high-level waste (SHLW). Chromosorb-W was found to be a better support material amongst the different solid supports evaluated viz. chromosorb-W, chromosorb-102, XAD-4 and XAD-7. Uptake profiles of various metal ions, such as U(VI), Pu(IV), Am(III), Eu(III), Fe(III), Sr(II) and Cs(I) were obtained as a function of acidity by batch studies using TODGA/chromosorb-W. Effect of macro concentration of Nd, Fe and U suggested that the uptake of Am(III) is mainly influenced by the presence of trivalent lanthanide ions. Breakthrough capacity of the resin material for Am(III) in presence of macro amount of Eu(III) was determined in the successive cycles of loading and elution. Loading capacity of the column was found to be 20 mg of Eu/g of the resin material. Elution studies of Am(III) suggested that 0.01 M EDTA was effective amongst different eluents used.     

Single-beam analysis of damaged beams: Comparison using Euler–Bernoulli and Timoshenko beam theory

A new general formulation that is applicable to the damaged, linear elastic structures ‘unified framework’ is used to obtain analytical expressions for natural frequencies and mode shapes. The term mode shapes is used to mean the displacement modes, the section rotation modes, the sectional bending strain modes and sectional shear strain modes. The formulation is applicable to damaged elastic self-adjoint systems. The formulation has two unique aspects: First, the theory is mathematically rigorous since no assumptions are made regarding the physical behavior at a damage location, therefore there is no need to substitute the damage with a hypothetical elastic element such as a spring. Since the beam is not divided at the damage location, rather than an 8 by 8, only a 4 by 4 matrix is solved to obtain the natural frequencies and mode shapes. Second, the inertia effects due to damage which have till now been neglected by researchers are accounted for. The formulation uses a geometric damage model, perturbation of mode shapes and natural frequencies, and a modal superposition technique to obtain and solve the governing differential equation. Timoshenko beam theory is then taken as an example, and its results are compared with results using Euler–Bernoulli beam theory and finite element models. The range of applicability of the two theories is ascertained for damage characteristics such as depth and extent of damage and beam characteristics such as slenderness ratio and Poisson?s ratio. The paper considers rectangular notch like non-propagating damage as an example of the damage.     

Designs of all-optical NOR gates using SOA based MZI

The paper investigates the non-linear behavior of semiconductor optical amplifier with Mach–Zehnder interferometer (SOA-MZI) configuration which makes it to work as a logic gate. The two designs of NOR gate based on SOA-MZI have been verified. The basic principal of both designs are same. The summation of data pulses have been taken and inverted to perform a NOR operation. In the design, the first 3 dB coupler creates a phase difference of π/2 in clock pulse and data pulse while passing through two interferometer arms. The clock and data pulses pass through SOA which attenuates the clock pulse wherever the data pulse is present. After passing through second 3 dB coupler a phase difference of π/2 is again created. Therefore, if the clock pulse is in the same phase will be added and if it is out of phase, will be canceled. The designs have been investigated at different bit-rates to achieve higher extinction ratio (ER), Q-factor and bit-error rate (BER) for different pump currents of SOA.     

Design and performance analysis in multiuser optical CDMA systems

The article presents comparative performance analysis of the proposed Optical CDMA system for 32 and 16 users with two dimensional codes. Numerical simulations have been done under interference significant environment, considering noise and dark current at data rates 2.5, 5, 7.5 and 10 Gbps over single mode fiber for transmission distance of more than 270 km. Results illustrate overall good performance, degraded with augment in bit rate and transmission distance, impervious with raise in number of simultaneous active users. Depicts significant performance improvement with inclusion of forward error correction RS (255,239), for low attenuation and chirp factor. It perceived, this is one of the efficient functional techniques for next generation broadband optical networks together with higher security owing to encoding and decoding, as it allow multiple users in the network to access the same fiber channel asynchronously.     

Tuning electrochemical potential of LiCoO2 with cation substitution: first-principles predictions and electronic origin

With a goal to improve the performance of LiCoO₂ as a cathode material in Li-ion batteries, we simulate substitution of various elements (X = Be, Mg, Al, Ga, Si and Ti) for Co using first-principles density functional theory and predict changes in its electrochemical potential. While the electrochemical potential of LiCoO₂ is enhanced with substitution of Be, Mg, Al and Ga for Co, an opposite effect is predicted of Si and Ti substitution. We determine the electronic origin of these changes in electrochemical potential using (a) Bader method of topological analysis of charge density, (b) partial density of electronic states to estimate oxidation states of metal and oxygen, and charge re-distribution upon lithiation. We find that the distribution of electronic charge donated by Li is influenced by the nature of the X–O bond. A larger electron transfer to O (in XO₆ octahedron) upon lithiation leads to stronger Li intercalation and thereby higher electrochemical voltage. Our findings provide a platform for a rational design of cathode materials in Li batteries with enhanced voltage.     

Quantum Dynamical Approach to Various Scattering Mechanisms and Their Influences on Thermal Conductivity of Sr- and Zn-Doped La2CuO4 High-Temperature Superconductor Cuprate

JETP Letters - A theoretical investigation of the thermal conductivity of lightly Sr- and Zn-doped La2CuO4 high temperature superconductor cuprates has been analyzed auspiciously. We used a quantum...     

Droplet shape analysis and permeability studies in droplet lipid bilayers

We apply optical manipulation to prepare lipid bilayers between pairs of water droplets immersed in an oil matrix. These droplet pairs have a well-defined geometry allowing the use of droplet shape analysis to perform quantitative studies of the dynamics during bilayer formation and to determine time-dependent values for the droplet volumes, bilayer radius, bilayer contact angle, and droplet center-line approach velocity. During bilayer formation, the contact angle rises steadily to an equilibrium value determined by the bilayer adhesion energy. When there is a salt concentration imbalance between droplets, there is a measurable change in the droplet volume. We present an analytical expression for this volume change and use this expression to calculate the bilayer permeability to water.     

Dopant induced morphologies of ZnS nanoparticles

We have reported the synthesis of cubic (zinc blende) phase ZnS: Ni²⁺ nanoparticles using a simple wet‐chemical method. Synthesized ZnS: Ni²⁺ nanoparticles had been characterized by X‐ray diffraction (XRD) and Energy Dispersive X‐ray (EDX) analysis. Surface morphologies were studied using Scanning Electron Microscopy (SEM). Fourier Transform Infrared (FTIR) spectra of selected samples were also carried out to confirm the presence of capping agent on the surface of the material. We have demonstrated that various morphologies like spherical, tetrapods, sheet and long‐armed multipods are emerged by simple chemical route without any vigorous reaction parameters and changing the concentration of dopant ions only. The probable mechanism for such morphologies has also been suggested.     

Observation of bulk like magnetic ordering below the blocking temperature in nanosized zinc ferrite

We investigated the magnetic behavior of nanosized zinc ferrite with the help of vibrating sample magnetometry and in-field Mössbauer spectroscopy. The nanoparticles of zinc ferrite with crystallite size ranging from 10 to 62 nm were synthesized by a nitrate method. The structure and phase were determined with the help of X-ray diffraction. Attributes of cation inversion were found with the calculated values of lattice parameter. The saturation magnetization decreases with the increase in crystallite size at room temperature, while these values are almost the same at 10 K for all the samples except the one with crystallite size of 10 nm. The thermal magnetization measurement shows a decrease in blocking temperature with increase in particle size for these samples. The synthesized samples exhibit the presence of antiferromagnetic ordering below the blocking temperature as investigated by in-field Mössbauer spectroscopy.