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81.
M. Chandra Sekhar P. Kondaiah S.V. Jagadeesh Chandra G. Mohan Rao S. Uthanna 《Applied Surface Science》2011,258(5):1789
Titanium dioxide (TiO2) films have been deposited on glass and p-silicon (1 0 0) substrates by DC magnetron sputtering technique to investigate their structural, electrical and optical properties. The surface composition of the TiO2 films has been analyzed by X-ray photoelectron spectroscopy. The TiO2 films formed on unbiased substrates were amorphous. Application of negative bias voltage to the substrate transformed the amorphous TiO2 into polycrystalline as confirmed by Raman spectroscopic studies. Thin film capacitors with configuration of Al/TiO2/p-Si have been fabricated. The leakage current density of unbiased films was 1 × 10−6 A/cm2 at a gate bias voltage of 1.5 V and it was decreased to 1.41 × 10−7 A/cm2 with the increase of substrate bias voltage to −150 V owing to the increase in thickness of interfacial layer of SiO2. Dielectric properties and AC electrical conductivity of the films were studied at various frequencies for unbiased and biased at −150 V. The capacitance at 1 MHz for unbiased films was 2.42 × 10−10 F and it increased to 5.8 × 10−10 F in the films formed at substrate bias voltage of −150 V. Dielectric constant of TiO2 films were calculated from capacitance–voltage measurements at 1 MHz frequency. The dielectric constant of unbiased films was 6.2 while those formed at −150 V it increased to 19. The optical band gap of the films decreased from 3.50 to 3.42 eV with the increase of substrate bias voltage from 0 to −150 V. 相似文献
82.
In this paper, we consider the Riemann problem and interaction of elementary waves for a nonlinear hyperbolic system of conservation laws that arises in shallow water theory. This class of equations includes as a special case the equations of classical shallow water equations. We study the bore and dilatation waves and their properties, and show the existence and uniqueness of the solution to the Riemann problem. Towards the end, we discuss numerical results for different initial data along with all possible interactions of elementary waves. It is noticed that in contrast to the p -system, the Riemann problem is solvable for arbitrary initial data, and its solution does not contain vacuum state. 相似文献
83.
Chandra Sekhar Pedamallu Linet Özdamar Tibor Csendes Tamás Vinkó 《Journal of Global Optimization》2008,42(3):369-384
A new efficient interval partitioning approach to solve constrained global optimization problems is proposed. This involves
a new parallel subdivision direction selection method as well as an adaptive tree search. The latter explores nodes (intervals
in variable domains) using a restricted hybrid depth-first and best-first branching strategy. This hybrid approach is also
used for activating local search to identify feasible stationary points. The new tree search management technique results
in improved performance across standard solution and computational indicators when compared to previously proposed techniques.
On the other hand, the new parallel subdivision direction selection rule detects infeasible and suboptimal boxes earlier than
existing rules, and this contributes to performance by enabling earlier reliable deletion of such subintervals from the search
space. 相似文献
84.
Poly(butyl acrylate) (PBA)/sodium silicate (SS) nanocomposites were prepared via emulsifier-free emulsion technique in presence of Cu(II)/glycine chelate complex and ammonium persulfate (APS) initiator. The strongly hydrophobic PBA was intercalated into the hydrophilic SS layer. Since the interlayers of silicate were filled with sodium cations, the hydrophilic properties were enhanced and lead to high degree of swelling. The formation of the PBA/SS nanocomposite was confirmed by infrared spectra (IR). Furthermore, as evidenced by transmission electron microscopy (TEM), the composite so obtained was found to have nanoscale structure. X-ray diffraction (XRD) was used to characterize the nanoscale dispersion of the layer silicate and useful for measurement of d-spacing in interlayer system. It was found from thermogravimetric analysis that PBA/SS nanocomposites had more thermal stability as compared to raw PBA due to intercalation. Burning test of the nanocomposites performance exhibited a flame retardant property, which was also verified from cone calorimeter analysis. For its commercialization, the ecological friendly nature was studied via biodegradation and was found to have better biodegradability than the raw PBA. 相似文献
85.
B. K. Rana R. M. Tripathi S. K. Sahoo N. K. Sethy V. S. Sribastav A. K. Shukla V. D. Puranik 《Journal of Radioanalytical and Nuclear Chemistry》2010,285(3):711-717
A brief study on dissolved radionuclides in aquatic environment, especially in ground water, constitutes the key aspect for assessment and control of natural exposure. In the present study the distribution of natural uranium and 226Ra concentration were measured in ground water samples collected within a 10 km radius around the Narwapahar uranium mine in the Singhbhum thrust belt of Jharkhand, India in 2007–2008. The natural uranium content in the ground water samples in this region was found to vary from 0.1 to 3.75 μg L?1 with an average of 0.87 ± 0.73 μg L?1 and 226Ra concentration was found to vary from 5.2 to 38.1 mBq L?1 with an average of 13.73 ± 7.34 mBq L?1. The mean annual ingestion dose due to intake of natural uranium and 226Ra through drinking water pathway to male and female adults population was estimated to be 6.55 and 4.78 μSv y?1, respectively, which constitutes merely a small fraction of the reference dose level of 100 μSv y?1 as recommended by WHO. 相似文献
86.
87.
Spatially homogeneous Bianchi types V and VI0 cosmological models are studied with source cosmic cloud strings coupled with electromagnetic field in Rosen’s (Gen. Relativ.
Gravit. 4:435, 1973) bimetric theory of relativity. It is observed that Bianchi type V space time is feasible whereas Bianchi type VI0 is not feasible. In the feasible case different equations of state for cosmic strings with Maxwell fields do not survive
in this theory and the space-time turns out to be flat. 相似文献
88.
Dibakar Sahoo Prosenjit Bhattacharya Hirak Kumar Patra Paulami Mandal Sankar Chakravorti 《Journal of nanoparticle research》2011,13(12):6755-6760
Change of α-helical structure of heme protein (Hb) to a β-sheet and random coil conformation because of the interaction of
glycine capped gold nanoparticles (20–60 nm) as observed from attenuation total reflectance, absorption, Fourier transform
infra red, and Circular Dichroism spectroscopy has been reported in this article. Upon interaction, protein takes a cylindrical
shape of length 12 μm and diameter 0.35 μm as revealed from scanning electron microscopy and transmission electron microscopy.
The Selected-Area Electron beam Diffraction pattern shows change of crystalline structure in GNP to amorphous nature with
the interaction of Hb. 相似文献
89.
MXenes are recently developed two-dimensional layered materials composed of early transition metal carbides and/or nitrides that provide unique characteristics for biosensor applications. This review presents the recent progress made on the usage and applications of MXenes in the field of electrochemical biosensors, including microfluidic biosensors and wearable microfluidic biosensors, and highlights the challenges with possible solutions and future needs. The multilayered configuration and high conductivity make these materials as an immobilization matrix for the biomolecule immobilization with activity retention and to be explored in the fabrication of electrochemical sensors, respectively. First, how the MXene nanocomposite as an electrode modifier affects the sensing performance of the electrochemical biosensors based on enzymes, aptamer/DNA, and immunoassays is well described. Second, recent developments in MXene nanocomposites as wearable biosensing platforms for the biomolecule detection are highlighted. This review pointed out the future concerns and directions for the use of MXene nanocomposites to fabricate advanced electrochemical biosensors with high sensitivity and selectivity. Specifically, possibilities for developing microfluidic electrochemical sensors and wearable electrochemical microfluidic sensors with integrated biomolecule detection are emphasized. 相似文献
90.
Bikash Sahoo 《Central European Journal of Physics》2010,8(3):498-508
The entrained flow of an electrically conducting non-Newtonian, viscoelastic second grade fluid due to an axisymmetric stretching
surface with partial slip is considered. The partial slip is controlled by a dimensionless slip factor, which varies between
zero (total adhesion) and infinity (full slip). Suitable similarity transformations are used to reduce the resulting highly
nonlinear partial differential equation into an ordinary differential equation. The issue of paucity of boundary conditions
is addressed, and an effective numerical scheme has been adopted to solve the obtained differential equation even without
augmenting the boundary conditions. The important findings in this communication are the combined effects of the partial slip,
magnetic interaction parameter and the second grade fluid parameter on the velocity and skin friction coefficient. It is observed
that in presence of slip, the velocity decreases with an increase in the magnetic parameter. That is, the Lorentz force which
opposes the flow leads to enhanced deceleration of the flow. Moreover, it is interesting to find that as slip increases in
magnitude, permitting more fluid to slip past the sheet, the skin friction coefficient decreases in magnitude and approaches
zero for higher values of the slip parameter, i.e., the fluid behaves as though it were inviscid. 相似文献