Effect of compact density and preheating temperature of the Al-Ti-C Preform on the fabrication of in-situ Mg–TiC composites

Magnesium reinforced in-situ TiC particulates was successfully synthesized utilizing the self-propagating high temperature synthesis (SHS) process .The result showed that preform temperature and compact density have a significant effect on the SHS reaction. When the compact density was 68 % of the theoretical density, no SHS reaction was observed. However, with an increase in density from 68 to 72 %, the successful thermal explosion reaction was observed in the Mg- melt. Besides, the effect of pre-heat temperature on the fabrication of Mg/TiC composite was extensively studied and it was found that the preheat temperature of 300 0C failed to give rise to SHS reaction. However, the increased pre-heat temperature of 450, 500 and 550 0C favors the reaction inside the liquid melt, but when the temperature is 600 0C, the ignition reaction occurred in the preheating furnace itself

Genetic Affinities of the Central Indian Tribal Populations

Background: The central Indian state Madhya Pradesh is often called as ‘heart of India ’ and has always been an important region functioning as a trinexus belt for three major language families (Indo-European, Dravidian and Austroasiatic). There are less detailed genetic studies on the populations inhabited in this region. Therefore, this study is an attempt for extensive characterization of genetic ancestries of three tribal populations, namely; Bharia, Bhil and Sahariya, inhabiting this region using haploid and diploid DNA markers. Methodology/Principal Findings: Mitochondrial DNA analysis showed high diversity, including some of the older sublineages of M haplogroup and prominent R lineages in all the three tribes. Y-chromosomal biallelic markers revealed high frequency of Austroasiatic-specific M95-O2a haplogroup in Bharia and Sahariya, M82-H1a in Bhil and M17-R1a in Bhil and Sahariya. The results obtained by haploid as well as diploid genetic markers revealed strong genetic affinity of Bharia (a Dravidian speaking tribe) with the Austroasiatic (Munda) group. The gene flow from Austroasiatic group is further confirmed by their Y-STRs haplotype sharing analysis, where we determined their founder haplotype from the North Munda speaking tribe, while, autosomal analysis was largely in concordant with the haploid DNA results. Conclusions/Significance: Bhil exhibited largely Indo-European specific ancestry, while Sahariya and Bharia showed admixed genetic package of Indo-European and Austroasiatic populations. Hence, in a landscape like India, linguistic labe

Directing Monolayer Tungsten Disulfide Photoluminescence using a Bent Plasmonic Nanowire on a Mirror Cavity

Designing directional optical antennas without compromising the field enhancement requires specially designed optical cavities. Herein, we report on the experimental observations of directional photoluminescence emission from a monolayer Tungsten Disulfide using a bent-plasmonic nanowire on a mirror cavity. The geometry provides field enhancement and directivity to photoluminescence by sandwiching the monolayer between an extended cavity formed by dropcasting bent silver nanowire and a gold mirror. We image the photoluminescence emission wavevectors by using the Fourier plane imaging technique. The cavity out-couples the emission in a narrow range of wavevectors with a radial and azimuthal spreading of only 11.0{\deg} and 25.1{\deg}, respectively. Furthermore, we performed three dimensional finite difference time domain based numerical calculations to corroborate and understand the experimental results. We envisage that the results presented here will be readily harnessed for on-chip coupling applications and in designing inelastic optical antennas

Directional emission from WS2 monolayer coupled to plasmonic Nanowire-on-Mirror Cavity

Influencing spectral and directional features of exciton emission characteristics from 2D transition metal dichalcogenides by coupling it to plasmonic nano-cavities has emerged as an important prospect in nanophotonics of 2D materials. In this paper we experimentally study the directional photoluminescence emission from Tungsten disulfide (WS2) monolayer sandwiched between a single-crystalline plasmonic silver nanowire (AgNW) waveguide and a gold (Au) mirror, thus forming an AgNW-WS2-Au cavity. By employing polarization-resolved Fourier plane optical microscopy, we quantify the directional emission characteristics from the distal end of the AgNW-WS2-Au cavity. Given that our geometry simultaneously facilitates local field enhancement and waveguiding capability, we envisage its utility in 2D material-based, on-chip nanophotonic signal processing, including nonlinear and quantum optical regimes.Comment: To appear in Advanced Photonics Research (2021

Mirror-Coupled Microsphere can narrow the Angular distribution of Photoluminescence from WS2 Monolayers

Engineering optical emission from two dimensional, transition metal dichalcogenides (TMDs) materials such as Tungsten disulphide (WS2) has implications in creating and understanding nanophotonic sources. One of the challenges in controlling the optical emission from 2D materials is to achieve narrow angular spread using a simple photonic geometry. In this paper, we study how the photoluminescence of a monolayer WS2 can be controlled when coupled to film coupled microsphere dielectric antenna. Specifically, by employing Fourier plane microscopy and spectroscopic techniques, we quantify the wavevector distribution in the momentum space. As a result, we show beaming of the WS2 photoluminescence with angular divergence of {\theta}1/2 = 4.6{\deg}. Furthermore, the experimental measurements have been supported by three-dimensional numerical simulations. We envisage that the discussed results can be generalized to a variety of nanophotonic 2D materials, and can be harnessed in nonlinear and quantum technology