Effects of extrinsic point defects in phosphorene: B, C, N, O and F Adatoms

Phosphorene is emerging as a promising 2D semiconducting material with a direct band gap and high carrier mobility. In this paper, we examine the role of the extrinsic point defects including surface adatoms in modifying the electronic properties of phosphorene using density functional theory. The surface adatoms considered are B, C, N, O and F with a [He] core electronic configuration. Our calculations show that B and C, with electronegativity close to P, prefer to break the sp3 bonds of phosphorene, and reside at the interstitial sites in the 2D lattice by forming sp2 bonds with the native atoms. On the other hand, N, O and F, which are more electronegative than P, prefer the surface sites by attracting the lone pairs of phosphorene. B, N and F adsorption will also introduce local magnetic moment to the lattice. Moreover, B, C, N and F adatoms will modify the band gap of phosphorene yielding metallic transverse tunneling characters. Oxygen does not modify the band gap of phosphorene, and a diode like tunneling behavior is observed. Our results therefore offer a possible route to tailor the electronic and magnetic properties of phosphorene by the adatom functionalization, and provide the physical insights of the environmental sensitivity of phosphorene, which will be helpful to experimentalists in evaluating the performance and aging effects of phosphorene-based electronic devices

Atomically thin group-V elemental films: theoretical investigations of antimonene allotropes

Group-V elemental monolayers including phosphorene are emerging as promising 2D materials with semiconducting electronic properties. Here, we present the results of first principles calculations on stability, mechanical and electronic properties of 2D antimony (Sb), antimonene. Our calculations show that free-standing {\alpha} and \b{eta} allotropes of antimonene are stable and semiconducting. The {\alpha}-Sb has a puckered structure with two atomic sub-layers and \b{eta}-Sb has a buckled hexagonal lattice. The calculated Raman spectra and STM images have distinct features thus facilitating characterization of both allotropes. The \b{eta}-Sb has nearly isotropic mechanical properties while {\alpha}-Sb shows strongly anisotropic characteristics. An indirect-direct band gap transition is expected with moderate tensile strains applied to the monolayers, which opens up the possibility of their applications in optoelectronics

Legal Rights for the Empowerment of Women: An Analytical Study

In India the status of women is very low in comparison to men. They treated as a subordinate in the society. Women in independent India have more rights than their counterparts in many other countries of the world. But most of our women are not very much conscious of their rights. If we talk about rural women, they are totally unaware about their rights due to high intensity of patriarchal values in the family. They are only busy in child bearing and other household activities. Such unawareness and less education make them feeble in comparison to men. Through the present paper the attempt has been made to focus on the status of women in Ancient India and in present India and their legal rights

A method for studying sequential faults on a three phase distribution transformer

A method has been presented for studying sequential faults on opposite sides of a three-phase distribution transformer using the theory of symmetrical components and Alpha, Beta, and Zero components of three-phase systems. The effect of the faults on the distribution system has also been analyzed and improvements in the protection scheme suggested. The sequential faults occurred, one after the other, on the distribution system of the Central Electric Power Cooperative of Jefferson City in the state of Missouri resulting in a double unbalanced fault condition. The data used in the example problem has been supplied through the courtesy of the above Cooperative. The problem has been solved in three stages, namely, for a two line to ground fault, an open conductor and the resulting double fault conditions with grounded transformer as well as with the ungrounded transformer when the grounding wire of the transformer burns out --Abstract, page ii

Degradation of Phosphorene in Air: Understanding at Atomic Level

Phosphorene is a promising two dimensional (2D) material with a direct band gap, high carrier mobility, and anisotropic electronic properties. Phosphorene-based electronic devices, however, are found to degrade upon exposure to air. In this paper, we provide an atomic level understanding of stability of phosphorene in terms of its interaction with O2 and H2O. The results based on density functional theory together with first principles molecular dynamics calculations show that O2 could spontaneously dissociate on phosphorene at room temperature. H2O will not strongly interact with pristine phosphorene, however, an exothermic reaction could occur if phosphorene is first oxidized. The pathway of oxidation first followed by exothermic reaction with water is the most likely route for the chemical degradation of the phosphorene-based devices in air

Phytosociological studies of grasslands in the vicinity of pataratu thermal power, Hazaribagh, Jharkhand

The study was conducted to assess the phytosociological studies of grasslands of Pataratu, Hazaribagh, Jharkhand. The total number of grassland species was recorded to be 17, 12 and 8 on control and 40, 27 and 19 on polluted grasslands in rainy, winter and summer seasons, respectively. Thero-hemicryptophytic life-forms was comparatively higher on both grasslands. Therophyte was higher on both grasslands than other life-forms classes.  The importance value index of Heteropogon contortus was recorded to be maximum as compared to other grasslands species present on both types of grasslands in rainy, winter and summer seasons

Carbon Allotrope Graphene: Superstar In Nano- World

Graphene is a substance made of pure carbon, with atoms arranged in a regular hexagonal pattern similar to graphite, but in a one-atom thick sheet. It is an allotrope of carbon whose structure is a single planar sheet of sp 2 -bonded carbon atoms that are densely packed in a honeycomb crystal lattice. Hence, graphene may be considered as the mother of graphite, fullerene and carbon nanotubes. Graphene can also be considered as the final member of the series of fused polycyclic aromatic hydrocarbons, such as naphthalene, anthracene and coronene It has many exceptional features which make it a superstar in the world of nanotechnology as thinnest material, practically transparent (3,000,000 sheets equal to 1mm), stiffest, strongest (Youngs modulus >0.51 TPa, tensile strength ~130 Gpa) largest surface-to-weight ratio (~2,700 m2/gram) very stretchable (stretch up to 20%), conducts heat and electricity better than any metal, impermeable to gases, large specific surface area, non-toxic, low cost and drug can attach on both sides of its sheet. Graphene can be successfully used as a non-toxic nano carrier for efficient gene transfection, a novel gene delivery, nano- vector with low cytotoxicity and high transfection efficiency, which is promising for future applications in non-viral-based gene therapy. Experimental studies have demonstrated that the shape of carbonaceous nanomaterials plays an extremely important role in how they interact with cells and potentially other biological systems, such as tissues and organisms. The cytotoxicity of graphene depends on the exposure environment and mode of interaction with cells as bacteria came directly contact with graphene, intensive physical interactions between graphene and bacterial cells may cause physical damages on cell membranes, and result in the release of intracellular contents and cytotoxicity and genotoxicity occur