Q-Switched Fiber Laser with a Hafnium-Bismuth-Erbium Codoped Fiber as Gain Medium and Sb2Te3 as Saturable Absorber

Journal of Russian Laser Research - We successfully demonstrate Q-switched fiber laser with a 20 cm long Hafnium-Bismuth-Erbium codoped fiber (HBEDF) as an active medium in conjunction with...     

A channel drop filter in hetero-woodpile-structure

By finite difference time domain method, a channel drop filter with four-port is designed, analyzed, and theoretically simulated in the hetero-woodpile-structure. Hetero-woodpile-structure includes three parts namely, along the propagation direction, the constant lattice in the core woodpile is different from two cladding woodpiles. This channel drop filter is comprised of two straight waveguides separated by an air-cavity in the same layer. Through simulations, we found that adjustment of the resonant-mode in heterostructure can be achieved in various ways, such as only changing the lattice constants, or changing both lattice constants, and the cavity size. The results also show that this structure can realize the energy transfer between bus and drop waveguides.     

Double injection–single detector flow injection spectrophotometric method for simultaneous determination of ascorbic acid and paracetamol in pharmaceutical formulations

Journal of the Iranian Chemical Society - A simple and low-cost flow injection spectrophotometric method was proposed for the simultaneous determination of ascorbic acid (AA) and paracetamol (PCM)...     

Experimental and numerical study on laminar natural convection in a cavity heated from bottom due to an inclined fin

Natural convection heat transfer in an inclined fin attached square enclosure is studied both experimentally and numerically. Bottom wall of enclosure has higher temperature than that of top wall while vertical walls are adiabatic. Inclined fin has also adiabatic boundary conditions. Numerical solutions have been done by writing a computer code in Fortran platform and results are compared with Fluent commercial code and experimental method. Governing parameters are Rayleigh numbers (8.10⁵ ≤ Ra ≤ 4 × 10⁶) and inclination angle (30° ≤ and ≤ 120°). The temperature measurements are done by using thermocouples distributed uniformly at the wall of the enclosure. Remarkably good agreement is obtained between the predicted results and experimental data. A correlation is also developed including all effective parameters on heat transfer and fluid flow. It was observed that heat transfer can be controlled by attaching an inclined fin onto wall.     

Electrochemical Sensing of Ascorbic Acid,Hydrogen Peroxide and Glucose by Bimetallic (Fe,Ni)−CNTs Composite Modified Electrode

In this research, bimetallic supported CNT modified electrode ( Fe,Ni/CNTs/GCE) has been developed for sensitive, stable and highly elctroactive sensing of glucose, ascorbic acid and hydrogen peroxide. Transition metals such as Iron (Fe) and Nickel (Ni) offer high electrical and thermal conductance, high active surface‐to‐volume ratio and presence of d‐band electrons gives enhanced electrocatalytic behavior. While, CNTs provide high surface area, stability and excellent conductivity. Synthesized material is characterized by SEM, EDS, XRD and FTIR to access morphology, elemental composition and structure. This unique combination is employed for the electrochemical sensing of ascorbic acid, glucose and hydrogen peroxide and different experimental parameters are optimized. Fe,Ni/CNTs/GCE shows good sensing efficiency at pH 7.4 which is ideally suitable for variety of analytes. The modified electrode also show good reproducibility and sensitivity under optimized conditions and can be reused upto 30 cycles without compromising the efficiency. With good linearity, reproducibility and limit of detection, this material possess significant potential as non‐enzymatic biosensor for variety of analytes.     

Physico-chemical analysis of semi-crystalline PEEK in aliphatic and aromatic solvents

Polyether ether ketone (PEEK) is a semi-crystalline thermoplastic polymer having excellent mechanical and thermal properties. Exposure of this polymer to aliphatic and aromatic solvents can lead to degradation or swelling of the polymeric material. The present work described the plasticization and stability analysis of semi-crystalline PEEK under different aromatic and aliphatic solvent environment. A variety of solvents (acetone, benzene, benzyl alcohol, chloroform, methanol, and toluene), based on their Hildebrand’s Solubility Parameter, were chosen for investigation. The physico-chemical characteristics of virgin and treated polymeric samples were investigated using Gas Chromatography–Mass Spectrometry (GC–MS), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and Fourier Transform Infrared Spectroscopy (FTIR) techniques. The results indicated that the solvent exposure did not significantly affect the thermal behavior and chemical structure of the polymer. However, it seems that certain components of the polymer were leached into the solvent phase as revealed by the GC–MS analysis. The present study identified PEEK as a potentially suitable polymer for the applications where high resistance to aliphatic and aromatic solvents is needed.     

Dependence of Nucleon and Pion-Induced Fission Cross Sections on the Level Density Parameter in the Cascade-Exciton Model

A new method is used to compute the fission cross sections in which a change of the ratio of the level density parameter in fission to neutron emission channels is taken into account with the change of the incident energy of the projectile. It is shown that fission cross sections induced by nucleons and pions depend on the ratio of the level density parameter in the fission and evaporation modes, i,e. af /an, respectively. We are unable to describe well the cross sections for fission without using this new method. The computed values exhibit reasonable agreement with the experimental data found in the literature across a wide range of beam energies.     

Leucosceptrine--a novel sesterterpene with prolylendopeptidase inhibitory activity from Leucosceptrum canum

A novel sesterterpene, leucosceptrine, was isolated from the medicinal plant Leucosceptrum canum from Nepal. The structure was determined by single-crystal X-ray diffraction and spectroscopic techniques. The biosynthesis of leucosceptrine (1) is proposed here. Leucosceptrine (1) exhibited prolylendopeptidase inhibitory activity.