Investigation of the lead-free double perovskites Cs2AgSbX6 (X= Cl, Br, I) for optoelectronic and thermoelectric applications

Perovskite compounds have the potential to harvest solar energy as well as exploit the thermoelectric potential of a number of available materials. Here, we present the electronic, structural, thermoelectric, and optical properties of Cs2AgSbX6 (X = Cl, Br, I) perovskite with the help of the density functional theory (DFT). The WC-GGA approximation was used to calculate the structural parameters. All these compounds crystalize in a cubic unit cell with lattice constant increasing from 10.65 {\AA} (Cl) to 11.14 {\AA} (Br) to 11.86 {\AA} (I). The mBJ-functional shows a semiconducting nature for these compounds with an indirect band gap lying at the L-X symmetry points. The optical conductivity and absorption coefficient show their peaks in the ultraviolet region, moving towards a lower energy range by inserting large size anion. The band gap of these compounds (2.08, 1.37, 0.64 eV) indicates their potential in single and multijunction solar cells. The value of refractive index at zero energy was evaluated to be 3.1, 2.2, and 1.97 for Cs2AgSbCl6, Cs2AgSbBr6 and Cs2AgSbI6. Effective mass of electrons is smaller than those of holes resulting in higher carrier mobility for electrons. The Seebeck coefficient, power factor, and the figure of merit were computed using the BoltzTrap code. The negative temperature coefficient of resistivity also supports the semiconductor nature of these compounds. The high electrical, small thermal conductivity, positive Seebeck coefficient, and the optimum figure of merit make these compounds suitable for thermoelectric applications.Comment: 11 pages, seven figures. arXiv admin note: text overlap with arXiv:2008.0512

Gold Nanoparticles: Synthesis and Applications in Drug Delivery

This review is focused essentially on the synthesis and applications of gold nanoparticles in the field of medicine and targeted drug delivery. Nanotechnology has become one of the most interesting and advanced areas of research in this field. Among nanoparticles, gold nanoparticles demonstrate special advantages in this field due to their unique properties, small size and high surface area-to-volume ratio. These particles have been widely used in various biomedical applications and drug delivery systems due to their inert nature, stability, high dispersity, non-cytotoxicity and biocompatibility.Keywords: Biosynthesis, Gold nanoparticles, Biomedical applications, Targeted drug delivery,Nanotechnology

Effect of compost addition on arsenic uptake, morphological and physiological attributes of maize plants grown in contrasting soils

Contamination of soils with arsenic (As) represents a global environmental and health issue considering the entrance of toxic As in the human food chain. Although partially understood, addition of compost for the remediation of As-contaminated soils may result in distinct effects on plant growth and physiological attributes depending on compost-mediated potential mobility/sequestration of As in soils. This study explores the role of compost addition (C; 0, 1 and 2.5%) on morphological and gas exchange attributes and photosynthetic pigments (chlorophyll contents) of maize plants under As stress (0, 40, 80, 120 mg kg− 1), as well as soil As immobilization/mobilization in a pot experiment, using two contrasting soils. Results revealed that, in Narwala (sandy loam) soil, the addition of compost decreased shoot As concentration of maize plants (p < 0.05; 4.01–13.7 mg kg− 1 dry weight (DW)), notably at C2.5 treatment, with significant improvement in shoot dry biomass, gas exchange attributes and chlorophyll (a and b) contents, i.e., 1.33–1.82, 1.20–2.65 and 1.34–1.66 times higher, respectively, over C0 at all As levels. Contrastingly, in Shahkot (clay loam) soil, C2.5 treatment increased shoot As concentration (p < 0.05; 7.02–17.3 mg kg− 1 DW), and as such reduced the shoot dry biomass, gas exchange attributes and chlorophyll contents, compared to the control – rather C1 treatment was more effective and exhibited positive effect than C2.5. Considerably, at C2.5 treatment, phosphate extractable (bioavailable) soil As concentration was also found to be greater in the (post-experiment) Shahkot soil than that of Narwala soil (0.40–3.82 vs. 0.19–1.51 mg kg− 1, respectively). This study advanced our understanding to resolve the complex compost-As interactions in As-contaminated soils, which are imperative to understand for developing the effective and soil-specific remediation strategies

Direct Exponent and Scalar Multiplication Classes of an MDS Matrix

An MDS matrix is an important building block adopted by different algorithms that provides diffusion and therefore, has been an area of active research. In this paper, we present an idea of direct exponent and direct square of a matrix. We prove that direct square of an MDS matrix results in an MDS matrix whereas direct exponent may not be an MDS matrix. We also delineate direct exponent class and scalar multiplication class of an MDS matrix and determine the number of elements in these classes. In the end, we discuss the standing of design properties of a cryptographic primitive by replacing MDS matrix by dynamic one