Studies of nonlinear optical properties of PicoGreen dye using Z-scan technique

In this paper we study the nonlinear optical properties of PicoGreen dye. The investigations involve the single-beam Z-scan technique and measurements were carried out at different incident intensities. Both open and closed aperture Z-scan techniques were performed at 532 nm and it was found that the dye exhibited a reverse saturable absorption with significant nonlinear absorption coefficient and intensity-dependent negative nonlinear refraction coefficient, indicating self-defocusing phenomena. The third-order nonlinear susceptibility and optical limiting threshold were also measured.     

Multiple-magnetic field 139La NMR and density functional theory investigation of the solid lanthanum(III) halides

Results from a solid-state ¹³⁹La NMR spectroscopic investigation of the anhydrous lanthanum(III) halides (LaX₃; X=F, Cl, Br, I) at applied magnetic fields of 7.0, 9.4, 11.7, 14.1, and 17.6 T are presented and highlight the advantages of working at high applied magnetic field strengths. The ¹³⁹La quadrupolar coupling constants are found to range from 15.55 to 24.0 MHz for LaCl₃ and LaI₃, respectively. The lanthanum isotropic chemical shifts exhibit an inverse halogen dependence with values ranging from −135 ppm for LaF₃ to 700 ppm for LaI₃, which represents nearly half of the total lanthanum chemical shift range. The spans of the magnetic shielding tensors also vary widely, from 35 to 650 ppm for the solid LaF₃ through LaI₃. DFT calculations of the ¹³⁹La electric field gradient and magnetic shielding tensors have been performed and provide a qualitative interpretation of the trends observed experimentally.     

Computation of Dispersion in Microstrip Line with Anisotropic Substrate and Overlay

This paper presents an analysis of frequency dependent propagation characteristics of microstrip lines with anisotropic substrate and overlay. The method involves setting up of the Greens functions corresponding to the structure and formulating a dispersion relation in Fourier transform domain. The dispersion relation is constructed in a Galerkins procedure. Numerical results are also presented.     

Behavior of pH-sensitive core shell particles at the air-water interface

In this article, the adsorption of latex core-responsive polymer-shell nanoparticles at the air-water interface is investigated using a Langmuir trough. Phase transition isotherms are used to explore their responsive behavior at the interface as a function of changes in the pH of the subphase. By adjusting the pH of the water prior to particle deposition, we probe the effect of the stabilizing polymer wetting by the water subphase on the stability of these particles at the air-water interface. In addition, by initially compressing a stable film of adsorbed particles and then subsequently changing the pH of the subphase we study desorption of these particles into the water phase.     

The Design of 3D-Printed Polylactic Acid–Bioglass Composite Scaffold: A Potential Implant Material for Bone Tissue Engineering

Bio-based and patient-specific three-dimensional (3D) scaffolds can present next generation strategies for bone tissue engineering (BTE) to treat critical bone size defects. In the present study, a composite filament of poly lactic acid (PLA) and 45S5 bioglass (BG) were used to 3D print scaffolds intended for bone tissue regeneration. The thermally induced phase separation (TIPS) technique was used to produce composite spheres that were extruded into a continuous filament to 3D print a variety of composite scaffolds. These scaffolds were analyzed for their macro- and microstructures, mechanical properties, in vitro cytotoxicity and in vivo biocompatibility. The results show that the BG particles were homogeneously distributed within the PLA matrix and contributed to an 80% increase in the mechanical strength of the scaffolds. The in vitro cytotoxicity analysis of PLA-BG scaffolds using L929 mouse fibroblast cells confirmed their biocompatibility. During the in vivo studies, the population of the cells showed an elevated level of macrophages and active fibroblasts that are involved in collagen extracellular matrix synthesis. This study demonstrates successful processing of PLA-BG 3D-printed composite scaffolds and their potential as an implant material with a tunable pore structure and mechanical properties for regenerative bone tissue engineering.     

Spectrophotometric Determination of Hydrogen Peroxide Using Leucocrystal Violet in Micellar Medium

A simple and sensitive spectrophotometric method for the determination of hydrogen peroxide, based on the increase in color intensity of dye on addition of surfactant, is described. Hydrogen peroxide is first reacted with potassium iodide in acidic medium, in presence of ammonium molybdate to liberate iodine. The liberated iodine oxidizes leucocrystal violet to crystal violet having maximum absorbance at 593 nm. The color of the dye intensifies with the addition of the surfactant, cetyl pyridinium chloride though the absorption maximum remains the same. Beer's law is obeyed in the range 0.05–0.45 µg of hydrogen peroxide per 25 mL of final solution (0.002–0.018 µg mL^?1) with an excellent correlation coefficient (r = 0.9977). The proposed method has been successfully applied for the analysis of hydrogen peroxide in various food products and rainwater.