Thermal effects on electron-phonon interaction in silicon nanostructures

Raman spectra from silicon nanostructures, recorded using excitation laser power density of 1.0 kW/cm^2, is employed here to reveal the dominance of thermal effects at temperatures higher than the room temperature. Room temperature Raman spectrum shows only phonon confinement and Fano effects. Raman spectra recorded at higher temperatures show increase in FWHM and decrease in asymmetry ratio with respect to its room temperature counterpart. Experimental Raman scattering data are analyzed successfully using theoretical Raman line-shape generated by incorporating the temperature dependence of phonon dispersion relation. Experimental and theoretical temperature dependent Raman spectra are in good agreement. Although quantum confinement and Fano effects persists, heating effects start dominating at higher temperatures than room tempaerature.Comment: 9 Pages, 3 Figures and 1 Tabl

Calcium enriched mixture cement: A review

Nothing is more valuable then preservation of the natural tooth, which reflects the general health of the patients. Dental caries is the most prevalent dental disease which needs various endodontic treatment procedures in order to maintain the tooth in healthy condition. With the advancement in material sciences, various new materials had evolved in dentistry.  One such material is calcium enriched mixture cement which is class of dental materials conciliates excellent biocompatibility with high osseoconductivity that render them ideal for endodontic care. The present article gives the overview of   newly developed novel endodontic cement

X-ray study of structural domains in the near-surface region of SrTiO₃ substrates with Y_0.6Pr_0.4Ba₂Cu₃O₇/La_2/3Ca_1/3MnO₃ superlattices grown on top

We investigated with synchrotron x-ray diffraction and reflectometry the formation of structural domains in the near-surface region of single crystalline SrTiO₃ (001) substrates with Y0.6Pr0.4Ba₂Cu₃O₇/La2/3Ca1/3MnO₃ superlattices grown on top. We find that the antiferrodistortive cubic to tetragonal transition, which occurs at TSTO=104  K in the bulk and at a considerably higher temperature of at least 120 K in the surface region of SrTiO₃, has only a weak influence on the domain formation. The strongest changes occur instead in the vicinity of the tetragonal to orthorhombic transition in SrTiO₃ around 65 K where pronounced surface facets develop that reach deep (at least several micrometers) into the SrTiO₃ substrate. These micrometer-sized facets are anisotropic and tilted with respect to one another by up to 0.5° along the shorter direction. Finally, we find that a third structural transition below 30 K gives rise to significant changes in the spread of the c-axis parameters. Overall, our data provide evidence for a strong mutual interaction between the structural properties of the SrTiO₃ surface and the multilayer grown on top

Development of a pyramidal magneto-optical trap for pressure sensing application

Here, we report the development and working of a compact rubidium (Rb) atom magneto-optical trap (MOT) operated with a hollow pyramidal mirror and a single laser beam. This type of compact MOT is suitable for developing portable atom-optic devices, as it works with less number of optical components as compared to conventional MOT setup. The application of this compact MOT setup for pressure sensing has been demonstrated

Exploring the impact of salinity on citrus (Citrus spp.) rootstock seed germination and seedling biomass

An experiment was conducted at the screen house of the Department of Horticulture, CCS Haryana Agricultural University, Hisar, Haryana during 2018–19 and 2019–20 to assess the impact of 5 different salinity levels [0.07 (control), 2.5, 4.0, 5.5, and 7.0 dS/m] on the seed germination and biomass of 9 citrus (Citrus spp.) rootstock seedlings (Rough lemon, Pectinifera, Cleopatra mandarin, Rangpur lime, Alemow, Volkamer lemon, NRCC-4, NRCC-3 and CRH-12). Experiment consisted of 45 treatment combinations and 3 replications in a completely randomized design (CRD). Under the influence of soil salinity, the number of days taken for seed germination, seed germination percentage, fresh and dry root and shoot biomass were adversely affected across all rootstocks compared to the control treatment (0.07 dS/m). Among the tested rootstocks, Volkamer lemon exhibited the highest seed germination rate (57%), followed by Rangpur lime (53%) and CRH-12 (50%). Conversely, Pectinifera showed the lowest seed germination percentage (37%), followed by Alemow (43%) at 7 dS/m. The minimum reduction at 7 dS/m over control in fresh shoot and root and dry shoot and root biomass was observed in Rangpur lime (37.7, 16.2, 27.8 and 27.3%, respectively), followed by Volkamer lemon (38.0, 16.2, 28.3 and 28.5%, respectively). On the other hand, Pectinifera exhibited the highest reduction in biomass (51.9, 40.5, 47.0 and 43.9%, respectively), followed by Alemow (45.7, 30.9, 46.5 and 39.9%, respectively). Among all the rootstocks, Rangpur lime, Volkamer lemon and Cleopatra mandarin displayed better tolerance to salinity, exhibiting relatively lower reduction in biomass at the highest salinity level (7 dS/m) compared to the control. Cleopatra mandarin, Rough lemon and NRCC-3 showed a moderate response, while Pectinifera, NRCC-4, and Alemow were found to be less tolerant, exhibiting higher reduction in terms of count of seed germination days, seed germination percentage, fresh and dry root biomass, and shoot biomass at 7 dS/m compared to the control treatment

An experimental insight of friction stir welding of dissimilar AA 6061/Mg AZ 31 B joints

In the present scenario, aerospace and automobile industries depend on lightweight materials such as magnesium and aluminum alloys because of their great balance between mechanical properties and weight ratio. Despite these benefits during the joining process of these dissimilar materials by welding, many challenges arises. The prominent one is related to the low melting points of these lightweight metals which make it almost impossible the joining using conventional arc welding techniques. To tackle this challenge, Friction Stir Welding (FSW) can be considered as a promising candidate tool. In this study, to demonstrate the FSW performances of joining two dissimilar materials we have investigated the joining of AA 6061 and Mg AZ 31 B using a built-in house a modified milling machine. The dissimilar combinations of AA 6061 and Mg AZ 31 B joints were successfully joined by embedding different welding conditions and varying the offset distance. The mechanical performances were evaluated by conducting specific mechanical tests such as micro-hardness, tensile, and impact tests, respectively. To explain the mechanical results, we have applied optical microscopy observation on the microstructure associated with the bonding location. The results prove that the strength of the Friction Stir Welded joints is much higher as compared to other techniques especially in terms of dissimilar metals