Estimation of compensation ratio by identifying the presence of different hopping conduction mechanisms in SnO2 thin films

WOS: 000287543300044The electrical properties of undoped SnO2 thin films prepared by the sol-gel technique were investigated by conductivity measurements in a temperature range of 50-200 K. Structural characterizations of the films were performed by atomic force microscopy and X-ray diffraction. Optical properties of the samples were also characterized by optical absorption spectroscopy. The different hopping models were used to investigate the characteristics of electrical conduction by hopping in employed temperature range. It was shown that three types of behavior can be expected, nearest-neighbour hopping at high temperatures, the Mott variable-range hopping at low temperatures and Efros-Shklovskii variable-range hopping at lower temperatures. The criteria for the observation of these three regions were established and the transitional behavior of the conductivity was determined. The experimentally determined critical transition temperatures were at the orders of magnitudes with what could be expected based on hopping conduction calculations. Under these analyses, the compensation ratio of the films was determined. (C) 2010 Elsevier B.V. All rights reserved.State of Planning Organization of TurkeyTurkiye Cumhuriyeti Kalkinma Bakanligi [2001K120590]; Ankara University BAPAnkara University [2007-07-45-054]This work is supported by the State of Planning Organization of Turkey under Grant No. 2001K120590 and the Ankara University BAP under Project Number 2007-07-45-054. We would also like to thank Prof. Dr. Yusuf Kagan Kadioglu and Ms. Murat Yavuz for providing XRD and AFM measurements

Ab initio study of bilateral doping within the MoS2-NbS2 system

We present a systematic study on the stability and the structural and electronic properties of mixed molybdenum-niobium disulphides. Using density functional theory we investigate bilateral doping with up to 25 % of MoS2 (NbS2) by Nb (Mo) atoms, focusing on the precise arrangement of dopants within the host lattices. We find that over the whole range of considered concentrations, Nb doping of MoS2 occurs through a substitutional mechanism. For Mo in NbS2 both interstitial and substitutional doping can co-exist, depending upon the particular synthesis conditions. The analysis of the structural and electronic modifications of the perfect bulk systems due to the doping is presented. We show that substitutional Nb atoms introduce electron holes to the MoS2, leading to a semiconductor-metal transition. On the other hand, the Mo doping of Nb2, does not alter the metallic behavior of the initial system. The results of the present study are compared with available experimental data on mixed MoS2-NbS2 (bulk and nanoparticles).Comment: 7 pages, 6 figure

The Minimal Supersymmetric Standard Model: Group Summary Report

CONTENTS: 1. Synopsis, 2. The MSSM Spectrum, 3. The Physical Parameters, 4. Higgs Boson Production and Decays, 5. SUSY Particle Production and Decays, 6. Experimental Bounds on SUSY Particle Masses, 7. References.Comment: 121 pages, latex + epsfig, graphicx, axodraw, Report of the MSSM working group for the Workshop "GDR-Supersym\'etrie",France. Rep. PM/98-4

Outbreak of Parasitic Dinoflagellate Piscinoodinium sp. Infection in an Endangered Fish from India: Arulius Barb (Dawkinsia arulius)

Freshwater velvet disease is caused by the dinoflagellate parasite, Piscinoodinium sp. This parasite has been reported in tropical and subtropical fishes, and it can cause devastating losses. Moreover, Piscinoodinium sp. is identified as one of the least studied finfish parasites, and the available molecular information about this parasite is meager. Recently, Piscinoodinium sp. was responsible for the 100% cumulative mortality of the captive-bred F1 generation of Arulius barb (Dawkinsia arulius), an endangered freshwater fish native to India. The trophont stages of the parasite were observed in the skin and gills of the affected fish. The total DNA was extracted from the trophonts collected from the affected Arulius barb and the partial nucleotide sequence of the rDNA complex region (2334 bp) was amplified using PCR. The amplified PCR product exhibited a high sequence identity (97.61%) with Piscinoodinium sp. In the phylogenetic analysis of the SSU rDNA, Piscinoodinium sp. emerged as a separate clade from other dinoflagellate species. This is the first report of the infection of Piscinoodinium sp. in Arulius barb and the molecular information generated from this study can serve as a baseline to study the diversity of the parasite in India. Furthermore, the impact of this parasite among wild fish stock is not known, and this parasite needs further research focus to generate more molecular information and to understand the host–pathogen interaction