Ethnobotanical Knowledge Studied in Pocharam Wildlife Sanctuary, Telangana, India

<p class="Continutabstract">A survey was conducted in 31 fringe villages of Pocharam wildlife sanctuary, Telangana, India, during 2010 to 2012, in order to explore and document the ethnobotanical knowledge of Yerukulas and Lambadis communities. There was revealed the use of 173 Angiosperm species. The pattern of the plant use as per habitat (terrestrial/aquatic), habit (growth form), plant part (organ) and taxonomic category (families), nativity and occurrence (wild/cultivated) were established. Dicots contribute more than Monocots to the medicinal and ethnobotanical use. This might be due to the species strength in the region. When the plant use-data were analyzed, trees contributed with 68 uses, followed by herbs (51), climbers (32) and shrubs (22). Perhaps this was a reflection of the floristic composition and the prevailing <em>Phanero-therophytic</em> climate. Out of the 173 plant taxa that were noted as being utilized by the ethnic people in the sanctuary, the greatest number (154; 89.1%) were indigenous and wild. The introduced species were the crops under cultivation and planted. Although the local people use plants for various purposes, they largely serve medicinal scopes (83.24%) and for subsistence (21.96%).</p

Flexible Flowlines: First Installation in Brunei

Shell TechXplorer25Netherland

Determination of strain relaxation in InGaN/GaN nanowalls from quantum confinement and exciton binding energy dependent photoluminescence peak

GaN based nanostructures are being increasingly used to improve the performance of various devices including light emitting diodes and lasers. It is important to determine the strain relaxation in these structures for device design and better prediction of device characteristics and performance. We have determined the strain relaxation in InGaN/GaN nanowalls from quantum confinement and exciton binding energy dependent photoluminescence peak. We have further determined the strain relaxation as a function of nanowall dimension. With a decrease in nanowall dimension, the lateral quantum confinement and exciton binding energy increase and the InGaN layer becomes partially strain relaxed which decreases the piezoelectric polarization field. The reduced polarization field decreases quantum confined Stark effect along the c-axis and increases electron-hole wave-function overlap which further increases the exciton binding energy. The strong dependency of the exciton binding energy on strain is used to determine the strain relaxation in these nanostructures. An analytical model based on fractional dimension for GaN/InGaN/GaN heterostructures along with self-consistent simulation of Schrodinger and Poisson equations are used to theoretically correlate them. The larger effective mass of GaN along with smaller perturbation allows the fractional dimensional model to accurately describe our system without requiring first principle calculations

Strong Size Dependency on the Carrier and Photon Dynamics in InGaN/GaN Single Nanowalls Determined Using Photoluminescence and Ultrafast Transient Absorption Spectroscopy

Here, we have demonstrated strong size dependency of quasi-equilibrium and nonequilibrium carrier and photon dynamics in InGaN/GaN single nanowalls using photoluminescence and transient absorption spectroscopy. We demonstrate that two-dimensional carrier confinement, strain relaxation, and modified density of states lead to a reduced Stokes shift, smaller full width at half-maxima, increased exciton binding energy, and reduced nonradiative recombination. The ultrafast transient spectroscopy shows that carrier capture is a two-step process dominated by optical phonons and carrier–carrier scattering in succession. The carrier capture is a strongly size-dependent process and becomes slower due to modulation of the density of available states for progressively decreasing nanowall sizes. The slowest process is the electron–hole recombination, which is also extremely size-dependent and the rate increases by almost an order of magnitude in comparison to that of quantum-well structures. Electron–hole wave function overlap and modified density of states are among the key aspects in determining all the properties of these structures

Thermally Grown TiO2 and Al2O3 for GaN-Based MOS-HEMTs

We have demonstrated the potential use of thermally grown TiO2 and Al2O3 oxides as gate dielectrics for GaN-based high-electron-mobility-transistors. TiO2 and Al(2)O(3 )are found to provide negative and positive band offsets with AIGaN, respectively. A significant performance improvement on various device characteristics provides evidence for its potential use. The oxides are formed by a combination of predeposition of a thin film and followed by oxidation in pure O-2 environment. The formation and thickness of the oxides are confirmed through the X-ray photoelectron spectroscopy and the transmission electron microscopy. The performance improvement for TiO2- and Al2O3-based oxide gates have been identified in terms of a ideality factor and a reduction in the gate leakage current in comparison with that of control devices. This is further augmented by an increase in the n(s) x mu product. The ON/OFF current ratio and turn-on voltage increase by 2-3 orders of magnitude and 0.3-0.6, respectively, for the Schottky diodes. The negative shift on the capacitance-voltage characteristics is also found to be minimal, indicating higher gate coupling with thermally grown oxides

Synthesis and characterization of magnesium oxide nanocrystallites and probing the vacancy-type defects through positron annihilation studies

International audienceMagnesium oxide nanocrystallites exhibit certain abnormal characteristics when compared to those of other wide band gap oxide semiconductors in the sense they are most prone to water absorption and formation of a hydroxide layer on the surface. The problem can be rectified by heating and pure nanocrystallites can be synthesized with controllable sizes. Inevitably the defect properties are distinctly divided between two stages, the one with the hydroxide layer (region I) and the other after the removal of the layer by annealing (region II). The lattice parameters, the optical band gap and even the positron annihilation characteristics are conspicuous by their distinct behavior in the two stages of the surface configurations of nanoparticles. While region I was specific with the formation of positronium-hydrogen complexes that drastically altered the defect-specific positron lifetimes, pick-off annihilation of orthopositronium atoms marked region II. The vacancy clusters within the nanocrystallites also trapped positrons. They agglomerated due to the effect of the higher temperatures and resulted in the growth of the nanocrystallites. The coincidence Doppler broadening spectroscopic measurements supported these findings and all the more indicated the trapping of positrons additionally into the neutral divacancies and negatively charged trivacancies. This is apart from the Mg2 monovacancies which acted as the dominant trapping centers for positrons

Selective Oxidation of Propylene to Propylene Oxide over Silver-Supported Tungsten Oxide Nanostructure with Molecular Oxygen

Propylene oxide (PO) is a versatile chemical intermediate, and by volume it is among the top 50 chemicals produced in the world. The catalytic conversion of propylene to PO by molecular oxygen with minimum waste production is of high significance from an academic as well as an industrial point of view. We have developed a new synthesis strategy to prepare 2–5 nm metallic silver nanoparticles (AgNPs) supported on tungsten oxide (WO₃) nanorods with diameters between 30 and 40 nm, in the presence of cationic surfactant (cetyltrimethylammonium bromide: CTAB), capping agent (polyvinylpyrrolidone: PVP), and hydrazine. The synergy between the surface AgNPs and WO₃ nanorods facilitates the dissociation of molecular oxygen on the metallic Ag surface to produce silver oxide, which then transfers its oxygen to the propylene to form PO selectively. The catalyst exhibits a PO production rate of 6.1 × 10^–2 mol g_cat^–1h^–1, which is almost comparable with the industrial ethylene-to-ethylene oxide production rate

Optimal PV Panel Reconfiguration Using Wireless Irradiance Distributed Sensing

The aim of this paper is to provide a dynamic reconfiguration method for partially shaded photovoltaic arrays. The implemented strategy is able to increase power production of the array with respect to the initial topology in real time and with any shading pattern. The array is supposed to be made of strings of modules interconnected in parallel and each module is constituted by series-connected photovoltaic cells. Irradiance values are calculated through a closed-form relation given the operating point of the modules, their temperatures, and their equivalent circuit model. This procedure frees the system from the necessity of costly pyranometers. The implemented method has been validated in Matlab environment simulating random shading conditions and implemented on a low-cost 32-bit microcontroller with wireless connectivity capabilities. The results prove the efficiency of the proposed solution