Measurement of στ product of solid state laser materials by an alternative method: Application to Nd3+ doped YVO4 crystal for 4 F 3/2→4 I 11/2 transition

In this paper an alternative approach for measurement of στ product for ⁴ F _3/2→⁴ I _11/2 transition of Nd³⁺ doped YVO₄ crystal is reported. In this method a microchip laser is formed by keeping a small piece of the sample in plane-plane resonator and a diode laser (808 nm) is used for pumping. The pump power induced thermal lensing effect is used to make the cavity stable. The cavity mode area is estimated by measuring the thermal lens focal length at the threshold and the average pump area is measured by Gaussian fit to the intensity profiles of the pump beam. The value of στ product of Nd:YVO₄ crystal obtained by this method is within 10% of the reported values. The advantage of this method is that it is a simple method for direct measurement of στ product of laser crystals.     

Implantation of the 111In/Cd Probe as InO− Ion for Radioisotope Tracer Studies

A radioisotope ion implanter has been developed using a cesium-sputtering, negative ion source, which offers versatility and sustained operation. Employing the molecular ¹¹¹In¹⁶O⁻ ion, μCi activities of the radioisotope probe ¹¹¹In/Cd have been implanted into different material hosts. The implanted tracer activity has been shown to be sufficient for LTNO, NMRON and PAC. A new NMRON resonance for ¹¹¹InAg was observed at 75.08 MHz. In₂O₃ powder performed well as the radioisotope carrier in the ion source, with the ratio of radioisotope and parasitic ion current being typically 4 × 10⁻⁴.     

Synthesis and Electronic Properties of Novel 5,7-Diazapentacene Derivatives

A route to the synthesis of novel 5,7-diazapentacenes and some preliminary studies on their properties is reported. A single crystal X-ray diffraction study of the dihexyl derivative showed it had formed a dimer during the analysis. The materials possess lower lying frontier orbitals than pentacene and may have potential applications in organic electronic devices. This synthetic method may be applicable to the synthesis of other azaacenes.     

Characterizations of Null Holomorphic Sectional Curvature of G C R-Lightlike Submanifolds of Indefinite Nearly K ¨ahler Manifolds

We obtain the expressions for sectional curvature, holomorphic sectional curvature and holomorphic bisectional curvature of a GCR-lightlike submanifold of an indefinite nearly K ¨ahler manifold and obtain characterization theorems for holo-morphic sectional and holomorphic bisectional curvature. We also establish a condi-tion for a GCR-lightlike submanifold of an indefinite complex space form to be a null holomorphically flat.     

Meticulous assessment of natural compounds from NPASS database for identifying analogue of GRL0617, the only known inhibitor for SARS-CoV2 papain-like protease (PLpro) using rigorous computational workflow

Molecular Diversity - The latest global outbreak of 2019 respiratory coronavirus disease (COVID-19) is triggered by the inception of novel coronavirus SARS-CoV2. If recent events are of any...     

Magnetization transfer and T2 quantitation in normal appearing cortical gray matter and white matter adjacent to focal abnormality in patients with traumatic brain injury

Traumatic brain injury (TBI) is one of the commonest causes of morbidity and mortality in the developed countries with posttraumatic epilepsy and functional disability being its major sequelae. The purpose of this study was to test the hypothesis whether the normal appearing adjacent gray and white matter regions on T2 and T1 weighted magnetization transfer (MT) weighted images show any abnormality on quantitative imaging in patients with TBI. A total of 51 patients with TBI and 10 normal subjects were included in this study. There were significant differences in T2 and MT ratio values of T2 weighted and T1 weighted MT normal appearing gray matter regions adjacent to focal image abnormality compared to normal gray matter regions in the normal individuals as corresponding contralateral regions of the TBI patient's group (p < 0.05). However the adjoining normal appearing white matter quantitative values did not show any significant change compared to the corresponding contralateral normal white matter values. We conclude that quantitative T2 and MT ratio values provide additional abnormality in patients with TBI that is not discernable on conventional T2 weighted and T1 weighted MT imaging especially in gray matter. This additional information may be of value in overall management of these patients with TBI.     

A study of damping in fiber-reinforced composites

Damping contributions from the viscoelastic matrix, interphase and the dissipation resulting from damage sites are considered to evaluate composite material damping coefficients in various loading modes. The paper presents the results of the FEM/Strain energy investigations carried out to predict anisotropic-damping matrix comprising of loss factors η₁₁, η₂₂, η₁₂ and η₂₃ considering the dissipation of energy due to fiber and matrix (two phase) and correlate the same with various micromechanical theories. Damping in three phase (i.e., fiber-interphase-matrix) composite is also calculated as an attempt to understand the effect of interphase. The contribution of energy dissipation due to sliding at the fiber-matrix interface is incorporated to evaluate its effect on η₁₁, η₂₂, η₁₂ and η₂₃ in fiber-reinforced composite having damage in the form of hairline debonding. Comparative studies of the various micromechanical theories/models with FEM/Strain energy method for the prediction of damping coefficients have shown consistency when both the effect of variable nature of stress and the fiber interaction is considered. Parametric damping studies for three phase composite have shown that the change in properties of fiber, matrix and interphase leads to a change in the magnitude of effectiveness of interphase, but the manner in which the interphase would affect the various loss factors depends predominately upon whether the hard or soft interphase is chosen. Analysis of the effect of damage on composite damping indicates that it is sensitive to its orientation and type of loading.     

Compact and efficient coupler to interface hybrid dielectric-loaded plasmonic waveguide with silicon photonic slab waveguide

A coupler is proposed to interface a hybrid dielectric-loaded plasmonic waveguide (HDLPW) with a silicon photonic slab waveguide. The HDLPW is firstly designed and optimized to attain the best tradeoff between the mode confinement and the propagation distance. The designed coupler is inspired from the taper configuration and numerically modeled through finite-difference time-domain (FDTD) simulation. The results demonstrate that a high confinement and low loss of the energy is achieved from a silicon photonic slab waveguide into the dielectric slot of area 50×200 nm² in the HDLPW. The transmission attained through the coupler with a compact size of 400 nm is found to be as high as 80% (1 dB). Further, the planar nature of taper configuration makes the coupler easy to fabricate using the state-of-the-art CMOS facilities. The proposed coupler is useful in enabling the integration between photonic and hybrid plasmonic waveguides and thus realizing on-chip hybrid integrated circuits.     

Improving the dielectric constant of Al2O3 by cerium substitution for high-k MIM applications

Process compatible high-k dielectric thin films are one of the key solutions to develop high performance metal–insulator–metal (MIM) structures for future microelectronic devices. Engineered cerium–aluminate (Ce_xAl_2–xO₃) thin films were deposited on titanium nitride metal electrodes by electron-beam co-evaporation of ceria and alumina in a molecular beam deposition chamber. X-ray photoelectron spectroscopy clearly reveals that Ce cations can be stabilized in the 3+ valence state in Ce_xAl_2–xO₃ up to x = 0.7 by accommodation in the alumina host matrix. Higher Ce content was observed to result in cerium dioxide segregation in cerium aluminate matrix, probably due to the chemical tendency of Ce cations to exist rather in the 4+ than in the 3+ state. Electrical characterization of the X-ray amorphous Ce_0.7Al_1.3O₃ films reveals a dielectric constant value of about 11 and leakage current lower than 10^?4 A/cm². No parasitic low-k interface formation between the high-k Ce_0.7Al_1.3O₃ film and the TiN metal electrode is detected.