Metal-semiconductor nanojunctions and their rectification characteristics

Junctions of silver-copper oxide and silver-zinc oxide, respectively were prepared within the pores of diameters, 20 nm, in anodic aluminium oxide membranes. Voltage-current characteristics were measured over the temperature range 373-573 K which showed rectification behaviour. Using the standard equation the difference between the work functions of the metal and the semiconductor was calculated. This showed a variation with the temperature of measurement. This is explained as arising due to the effect of pressure generated as a result of thermal expansion of the metallic phases concerned between the electrodes. This is consistent with the theoretical prediction of Fermi level shifting of the semiconductor within the bandgap as a function of pressure

Modulation de l'activité de GSK 3 beta et de la phosphorylation par la kinase PKR

PARIS7-Bibliothèque centrale (751132105) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Metallic behavior of copper sulfide nanowires grown within Na-4 mica

Copper sulfide nanowires of diameter of ~ 1.2 nm were grown within the crystal channels of Na-4 mica. These consist of both CuS and Cu<SUB>2</SUB>S strands. Electrical conduction over the temperature range of 130-300 K was characterized by very low activation energies in the range of 0.008-0.004 eV. The nanocomposites exhibit giant dielectric permittivity of ~ 1617 which has been explained on the basis of one-dimensional metallic nanowires as predicted by the Gorkov-Eliashberg [Sov. Phys. JETP 21, 940 (1965) ] and Rice-Bernasconi [Phys. Rev. Lett. 29, 113 (1972) ] models

Synthesis of two-dimensional metallic silver using sodium beta-alumina crystal channels

Sodium beta-alumina (β-NaAl<SUB>11</SUB>0<SUB>17</SUB>) crystals were grown within a gel containing Na<SUB>2</SUB>O and Al<SUB>2</SUB>O<SUB>3</SUB>. The glass-crystal composite was put through a Na<SUP>+</SUP> ↔ Ag<SUP>+</SUP> ion-exchange reaction. The ion-exchanged glass-crystal was then subjected to an electrodeposition process. Nanosheets of metallic silver were found to have grown within the β-NaAl<SUB>11</SUB>0<SUB>17</SUB> channels which usually contain the mobile sodium ions. The DC electrical resistance of the composites was caused due to charge transport in the two-dimensional crystal planes. The average silver layer thickness was ~0.6 nm and the interlayer separation ~1.13 nm

Electrical properties of compacted assembly of copper oxide nanoparticles

Cu2O nanoparticles with diameters in the range 6.0-8.6 nm were prepared by a chemical method. Both dc and ac electrical properties were measured on a compacted nanoparticle assembly. dc electrical resistivity in the temperature range 140-300 K was found to arise due to a variable range hopping conduction mechanism. The ac resistivity variation as a function of frequency (in the range 10 kHz to 3 MHz) and temperature (range 220-320 K) was explained on the basis of the power-law exponent in percolating clusters. The interfacial amorphous phase of the nanoparticle assembly appears to control the electrical behavior of the system

Intralesional Sclerotherapy with Polidocanol in the Management of Head and Neck Vascular Lesions

Introduction Vascular lesions (Hemangioma or vascular malformation) in the head and neck region are quite common and need therapeutic intervention if they become symptomatic or cosmetically unacceptable. Different therapeutic modalities including cryotherapy, corticosteroids, laser therapy, sclerotherapy, surgery and/or embolization are available. Advances in laser surgery as well as sclerotherapy techniques have improved our ability to treat extensive lesions. Surgical excision sometimes becomes very difficult due to massive per-operative bleeding and proximity to major neurovascular structures. In this study we have tried to find a simpler, easily available, safe and cost-effective therapy to treat these vascular lesions. Materials and Method         A pilot case study was conducted in a tertiary care hospital in Kolkata for a period of one year. Polidocanol was selected as the sclerosing agent for treatment of head and neck vascular lesions for its safety and its local anesthetic effect. 3% Polidocanol was injected in 20 lesions. Result 20 patients with head and neck vascular lesions treated with polidocanol sclerotherapy were followed up for 12 months. The study included 20 patients (12 female and 8 male) with mean age 20.3 years (range 6-62 years). Of these 20 patients 14 had 90% to 100% result and in 6 patients we obtained only mild improvement. Discussion Sclerotherapy is now becoming the first choice of treatment in head and neck vascular lesions. Polidocanol is a mixture of 5% ethyl alcohol and 95% hydroxypolyethoxydodecane, the detergent action of which induces a rapid overhydration of endothelial cells, leading to vascular injury and regression of vascular lesions. As the same time it is a local anesthetic, so treatment is painless. Conclusion It is a less invasive, cost effective, painless OPD based management for head and neck vascular lesions having good functional and aesthetic outcome

Multiferroic properties of NiS nanoplates grown within Na-4 mica

Nanoplates of NiS with thickness 0.6 nm were grown within the crystal channels of Na-4 mica. The thickness of the nanoplates is confirmed by atomic force microscopy. The nanocomposites exhibited multiferroic (both ferromagnetic and ferroelectric) behavior at room temperature. Ferromagnetism was adduced to an increase of surface defects as a result of the two-dimensional configuration of the sample. Ferroelectric behavior was explained as arising due to a small distortion in the crystal structure of NiS grown within the Na-4 mica channels. This was substantiated by the refined values of lattice constants as determined by profile matching of X-ray data by a computer program. A magnetodielectric effect was also observed in this nanocomposite with a change of 0.77% in the dielectric constant for a magnetic field of 0.6 T

Improved laboratory diagnosis of tuberculosis – the Indian experience

Tuberculosis (TB) is the leading cause of death worldwide attributable to a single infectious disease agent. India has more new TB cases annually than any other country. In 2008, India accounted for a fifth of the estimated 9.4 million TB cases globally. There is an overwhelming need for improving TB diagnostics in India through the use of cost effective, patient-friendly methods appropriate to different tiers of the country health system. Substantial progress has been made in India in the field of TB diagnosis and serious efforts have been made to herald the development of diagnostic tests for pulmonary TB, extra pulmonary TB and MDR-TB. Diverse approaches have been attempted towards improving smear microscopy, rapid culture and for differentiation between the Mycobacterium tuberculosis complex and non-tuberculous mycobacteria. Several laboratories have developed in-house PCR assays for diagnosing TB with high accuracy. Approaches for distinguishing M. tuberculosis and/or Mycobacterium bovis infection and disseminated Mycobacterium avium complex infection in HIV-AIDS patients have also been described. Serological tests to detect antigens or antibodies to M. tuberculosis specific components by using cocktails of Excretory/Secretory protein antigens, Ag85 complex antigens, Hsp 65 antigen, RD1 antigens and Rapid Reverse Line Blot Hybridization assays to detect MDR-TB (mutations to rifampicin, isoniazid and streptomycin) have also been developed. Other methods like measurement of adenosine deaminase activity and use of luciferase reporter phages have also been explored for TB diagnosis. These advances in the Indian context are detailed in the present chapter. The validation and application of these methods in laboratory and public health settings is likely to result in improved TB diagnosis and contribute to effective disease management in India