Spectroscopic study of &#946;-Ni(OH)<SUB>2</SUB> under pressure

Infrared absorption and Raman study of &#946;-Ni(OH)2 has been carried out up to 25 GPa and 33 GPa, respectively. The frequency of A2u internal antisymmetric stretching O-H mode decreases linearly with pressure at a rate of &#8722;0.7 cm&#8722;1/GPa. The FWHM of this mode increases continuously with pressure and reaches a value of ~ 20 cm&#8722;1 around 25 GPa. There was no discernible change observed in the frequency and width of the symmetric stretching A1g O-H Raman mode up to 33 GPa. The constancy of the Raman mode is taken as a signature of the repulsion produced by H-H contacts in this material under pressure. Lack of any discontinuity in these modes suggests that there is no phase transition in this material in the measured pressure range

Influence of defects on the quality and optical studies of sodium p-nitrophenolate dihydrate, a nonlinear optical material

Nonlinear optical material of sodium p-nitrophenolate dihydrate was synthesized by employing the technique of controlled evaporation and the effect of temperature on growth morphology was investigated. Single crystal XRD analysis confirms that the crystals with different morphologies have the same lattice parameters. The high-resolution X-ray diffraction curves recorded by a multicrystal X-ray diffractometer revealed the presence of very low angle tilt boundaries. The green emission band at 524 nm is due to the existence of defects on the crystal which corroborated with HRXRD studies. The wide band gap of the SPND crystals confirms the large transmittance in the visible region

Vibrational spectroscopic studies of Lithium para nitrophenolate trihydrate single crystal suitable for NLO applications

Single crystals of Lithium paranitrophenolate trihydrate have been grown using controlled evaporation technique. The grown crystals have been identified from single crystal XRD analysis. High Resolution X-Ray Diffraction experiments substantiate good crystalline perfection without having any internal structural grain boundaries. The low absorption in the 480 nm-1400 nm range enables it to be an apt candidate for electro-optic and NLO applications. FTIR, FT-Raman and FTNMR spectroscopic techniques have been used to elucidate the molecular structure of the title material

Growth, structural, optical, thermal and mechanical studies of novel semi-organic NLO active single crystal: Heptaaqua-p-nitrophenolato strontium (I) nitrophenol

Novel single crystals of Heptaaqua-4-nitrophenolato strontium(I) nitrophenol (HNSN) were successfully grown using slow evaporation solution growth technique at constant temperature (303 K) with dimensions 40×12×6 mm3. The formation of the new crystal has been confirmed by single-crystal X-ray diffraction, NMR, FT-IR and UV–vis–NIR studies. The crystalline perfection was analyzed by high-resolution X-ray diffraction (HRXRD) rocking curve measurements. Thermal analysis has also been carried out, and the thermal behavior of HNSN crystal has been studied. The dielectric loss and dielectric constant measurements as a function of frequency and temperature were measured for the grown crystal. The mechanical strength of the crystal is estimated by Vicker’s hardness test. The powder second harmonic generation (SHG) has been confirmed by Nd: YAG laser

Crystalline perfection, spectroscopic investigations and transport properties of trisglycine zinc chloride NLO single crystal

Bulk single crystals of trisglycine zinc chloride have been grown from aqueous solution by slow cooling technique. Single crystal and powder XRD analyses confirmed orthorhombic crystal structure with non-centrosymmetric space group Pbn2(1). High resolution X-ray diffraction results have established that the quality of the grown crystal is quite good for device fabrication. The crystal was characterized by FTIR and NMR spectral analyses. Optical absorption studies show that the material has very low absorption in the wavelength range 240-2000 nm. The analysis of absorption coefficient in the absorption region reveals a direct band gap of 4.21 eV. The crystal possesses remarkable thermal stability up to 229 degrees C. Photoconductivity studies of the grown crystal revealed the positive photoconducting nature. The grown crystal exhibited considerable hardness anisotropy with Vicker's hardness tester. Dielectric constant and dielectric loss were calculated by varying frequencies at different temperatures

Predictors of permanent pacemaker insertion after TAVR: A systematic review and updated meta-analysis

OBJECTIVES: The aim of this analysis was to evaluate the predictors associated with increased risk of permanent pacemaker implantation (PPMI) following transcatheter aortic valve replacement (TAVR). BACKGROUND: While TAVR has evolved as the standard of care for patients with severe aortic stenosis, conduction abnormalities leading to the need for PPMI is one of the most common postprocedural complications. METHODS: A systematic literature search was performed to identify relevant trials from inception to May 2020. Summary effects were calculated using a DerSimonian and Laird random-effects model as odds ratio with 95% confidence intervals for all the clinical endpoints. RESULTS: Thirty-seven observational studies with 71 455 patients were identified. The incidence of PPMI following TAVR was 22%. Risk was greater in men and increased with age. Patients with diabetes mellitus, presence of right bundle branch block, baseline atrioventricular conduction block, and left anterior fascicular block were noted to be at higher risk. Other significant predictors include the presence of high calcium volume in the area below the left coronary cusp and noncoronary cusp, use of self-expandable valve over balloon-expandable valve, depth of implant, valve size/annulus size, predilatation balloon valvuloplasty, and postimplant balloon dilation. CONCLUSION: Fourteen factors were found to be associated with increased risk of PPMI after TAVR, suggesting early identification of high-risk populations and targeting modifiable risk factors may aid in reducing the need for this post TAVR PPMI