New generation adsorbents for water treatment.

http://nathan.instras.com/documentDB/paper-44.pdf

Surface photovoltage phenomena: theory, experiment, and applications

Tin doped indium oxide (ITO) films are highly transparent in the visible region, exhibiting high reflectance in the infrared region, and having nearly metallic conductivity. Owing to this unusual combination of electrical and optical properties, this material is widely applied in optoelectronic devices. The association of these properties in a single material explains the vast domain of its applicability and the diverse production methods which have emerged. Although the different properties of tin doped indium oxide in the film form are interdependent, this article mainly focuses on the electrical aspects. Detailed description of the conduction mechanism and the main parameters that control the conductivity is presented. On account of the large varieties and differences in the fabrication techniques, the electrical properties of ITO films are discussed and compared within each technique.

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Tin doped indium oxide thin films: Electrical properties

▪ Abstract The synthesis of nanocrystalline diamond films from carbon-containing noble gas plasmas is described. The nanocrystallinity is the result of new growth and nucleation mechanisms, which involve the insertion of C2, carbon dimer, into carbon-carbon and carbon-hydrogen bonds, resulting in hetereogeneous nucleation rates on the order 1010 cm−2 s−1. Extensive characterization studies led to the conclusion that phase-pure diamond is produced with a microstructure consisting of randomly oriented 3–15-nm crystallites. By adjusting the noble gas/hydrogen ratio in the gas mixture, a continuous transition from micro- to nanocrystallinity is achieved. Up to 10% of the total carbon in the nanocrystalline films is located at 2 to 4 atom-wide grain boundaries. Because the grain boundary carbon is π-bonded, the mechanical, electrical, and optical properties of nanocrystalline diamond are profoundly altered. Nanocrystalline diamond films are unique new materials with applications in fields as diverse as tribolo...

Nanocrystalline diamond films1

We analyze theoretically the optical properties of ideal semiconductor crystallites so small that they show quantum confinement in all three dimensions [quantum dots (QD's)]. In the limit of a QD much smaller than the bulk exciton size, the linear spectrum will be a series of lines, and we consider the phonon broadening of these lines. The lowest interband transition will saturate like a two-level system, without exchange and Coulomb screening. Depending on the broadening, the absorption and the changes in absorption and refractive index resulting from saturation can become very large, and the local-field effects can become so strong as to give optical bistability without external feedback. The small QD limit is more readily achieved with narrow-band-gap semiconductors.

Theory of the linear and nonlinear optical properties of semiconductor microcrystallites

Boron nitride films were synthesized by r.f. plasma CVD technique using borane-ammonia, nitrogen and argon as the precursor gases. The films were deposited onto Si (100) and fused silica substrates kept at different substrate temperatures (573–703 K). Hot emissive probe was utilized to measure the ion energy of the radicals bombarding the substrate during deposition. Effects of substrate temperature, ion energy and ion current on the c-BN content in the films were determined. Bombardment of energetic ions during growth has profound effect on the film quality. Initial layer seemed to contain boron rich hexagonal B51–2 N phase.

Effect of ion energy and ion current on the synthesis of c-BN films by r.f. plasma CVD

Silicon doped polycrystalline gallium nitride films have been deposited at temperatures ranging from 300 to 623 K on fused silica and silicon substrates by radio frequency sputtering technique. The films are characterized by optical measurements while the microstructural information is obtained from scanning electron microscopy and atomic force microscopy. X-ray photoelectron spectroscopy studies indicate compositional information in these films. The bonding environment in the film has been revealed from Fourier transformed infrared studies. Grain boundary parameters like density of trap states and barrier height are also evaluated.

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Grain boundary scattering in silicon doped polycrystalline gallium nitride films prepared by rf sputtering

Evolutionary Dynamics of a Single-Species Population Model with Multiple Delays in a Polluted Environment

The paper aims to study the stability behaviour of a predator-prey system in deterministic and stochastic environment. In deterministic environment, we have studied the boundedness of the system, and stability of its equilibrium points. The growth rate of the prey and the death rate of the predator species are perturbed by Gaussian white noises to simulate a random environment. The resulting model is then cultured by the technique of statistical linearization, and criteria for non-equilibrium fluctuation and stability are derived. Computer simulation is carried out to validate our results on the deterministic stability of the interior equilibrium point. The implications of our analytical findings are discussed critically.

A Nonlinear Predator-Prey System in Deterministic and Stochastic Environment

We report a 12 year old boy of Nepalese origin with gastric adenocarcinoma and associated nodular lymphoid hyperplasia of the colon, with hemoglobin E trait and normal serum immunoglobulins The boy underwent a curative resection and is free of recurrence or metastasis nine months after diagnosis

A.K. Pal

Papers

Effect of ion energy and ion current on the synthesis of c-BN films by r.f. plasma CVD

Grain boundary scattering in silicon doped polycrystalline gallium nitride films prepared by rf sputtering

Evolutionary Dynamics of a Single-Species Population Model with Multiple Delays in a Polluted Environment

A Nonlinear Predator-Prey System in Deterministic and Stochastic Environment

Gastric carcinoma in a child associated with nodular lymphoid hyperplasia of the colon.