Search Results - (Author, Cooperation:K. Prasad)

2018-01-12

The American Society for Pharmacology and Experimental Therapeutics (ASPET)

0090-9556

1521-009X

Chemistry and Pharmacology

Medicine

2018-07-18

The American Society for Pharmacology and Experimental Therapeutics (ASPET)

0090-9556

1521-009X

Chemistry and Pharmacology

Medicine

2014-08-27

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Arabidopsis/cytology/*growth & development/*metabolism ; Arabidopsis Proteins/*metabolism ; Cell Differentiation ; Cell Movement ; Gene Expression Regulation, Plant ; Gravitropism ; Indoleacetic Acids/*metabolism ; Meristem/growth & development/metabolism ; Mitosis ; Plant Roots/cytology/growth & development/metabolism ; Transcription Factors/*metabolism

1745-6584

Blackwell Publishing Journal Backfiles 1879-2005

Energy, Environment Protection, Nuclear Power Engineering

Geosciences

Determination of aqueous phase diffusion coefficients of solutes through porous media is essential for understanding and modeling contaminant transport. Prediction of diffusion coefficients in both saturated and unsaturated zones requires knowledge of tortuosity and constrictivity factors. No methods are available for the direct measurement of these factors, which are empirical in their definition. In this paper, a new definition for the tortuosity factor is proposed, as the real to ideal interfacial area ratio. We define the tortuosity factor for saturated porous media (τs) as the ratio S/So (specific surface of real porous medium to that of an idealized capillary bundle). For unsaturated media, tortuosity factor (τa) is defined as 2awla (ratio of the specific air-water interfacial area of real and the corresponding idealized porous medium). This tortuosity factor is suitably measured using sorptive tracers (e.g., nitrogen adsorption method) for saturated media and interfacial tracers for unsaturated media. A model based on this new definition of tortuosity factors, termed the interfacial area ratio (IAR) model, is presented for the prediction of diffusion coefficients as a function of the degree of water saturation. Diffusion coefficients and diffusive resistances measured in a number of saturated and unsaturated granular porous media, for solutes in dilute aqueous solutions, agree well with the predictions of the IAR model. A comparison of permeability of saturated sands estimated based on τs and the same based on the Kozeny-Carman equation confirm the usefulness of the τs parameter as a measure of tortuosity.

Electronic Resource

1573-4811

Springer Online Journal Archives 1860-2000

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Electronic Resource

1573-4803

Springer Online Journal Archives 1860-2000

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Abstract Clad 2 mm thick sheets of Russian 1441 grade Al–Li alloys were welded using a gas tungsten arc welding process (GTAW). Comparisons were made between the weld beads obtained under (i) continuous current (CC), (ii) pulsed current (PC), and (iii) arc oscillation (AO) conditions for their macro- and microstructural details. In the case of CC GTAW, sound welds could be produced only under a narrow range of welding parameters. Centre line cracks, which occurred in CC GTAW welds under certain conditions, were halted by switching to PC or AO conditions while the welding was in progress. Microstructural refinement was significant in the case of PC and AO GTA welding.

Electronic Resource

1573-4811

Springer Online Journal Archives 1860-2000

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Electronic Resource

1573-4811

Springer Online Journal Archives 1860-2000

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Electronic Resource

0947-5117

Chemistry ; Polymer and Materials Science

Wiley InterScience Backfile Collection 1832-2000

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Einfluß des Deltaferritgehalts auf die Korrosionsbeständigkeit von mit Stahl 316 plattierten MetallenAustenitische Plattierungen mit Stahl 316 wurden durch Schutzgas-Metall-Lichtbogenschweißen und Unterpulverschweißen mit Elektroden aus 316 L auf niedrig gekohltem Kesselblech (SA 515 Gr 60) hergestellt, wobei Stahl 309 L als Sperrschicht mittels Unterpulverschwei-ßen aufgebracht wurde. Der Wärmeeintrag beim Schweißen wurde variiert, um in der Plattierung unterschiedliche Ferritgehalte einzustellen. Die plattierten Proben wurden nach dem Schweißen wärmebehandelt (650°C, 50 und 200 h). Die oberste Plattierungsschicht wurde abgetragen und die Proben anschließend auf Anfälligkeit für interkristalline Korrosion untersucht (ASTM A-262-75, A, B, C und E, d.h. 10% Oxalsäure, elektrolytisch, Eisensulfat + 50% ige Schwefelsäure; 65%ige Salpetersäure; Kupfer/Kupfersulfat -16%ige Schwefelsäure); außerdem wurde auch ein ätzversuch bei kontrolliertem Potential durchgefüuhrt.Die Untersuchung hat gezeigt, daß der Ferritgehalt der Plattierung mit zunehmender Stromstärke abnimmt. Der Anteil des umgewandelten Ferrits nach der Wärmebehandlung nach dem Schweißen war in den Plattierungen mit niedrigem Wärmeeintrag und hohem Ferritgehalt etwas erhöht. Die Wärmebehandlung im Anschluß an das Schweißen führte zum Sprödbruch von Plattierungen mit hohem Ferritgehalt (〉 als 10%).Der Korrosionsangriff des Ferrits ist abhängig vom jeweiligen Medium: 65% ige Schwefelsäure treibt den Ferrit bevorzugt an, während in Eisensulfat-Schwefelsäure der Ferrit intakt bleibt, der Austenit hingegen angegriffen wird. Keine der untersuchten Proben war im unbehandelten Plattierungszustand oder nach Wärmebehandlung anfällig für interkristalline Korrosion in Kupfer/Kupfersulfat -16% Schwefelsäure. Proben mit niedrigem Ferritgehalt (3,55%), die nach dem Schweißen wärmebehandelt wurde, wiesen an der Grenzfläche zwischen zwei benachbarten Schichten Korngrenzenausscheidungen auf. Im allgemeinen hat sich der Ferrit als günstig für das Korrosions-verhalten von plattierten Metallen nach Wärmebehandlung erwiesen. Der Wärmeeintrag im untersuchten Bereich führte zu keiner wesentlichen Beeinflussung der Korrosionsgeschwindigkeit.

Austenitic claddings of type 316 were obtained by SMAW (Shielded Metal Arc Welding) and SAW (Submerged Arc Welding) processes, using type 316 L electrodes on low carbon boiler steel (SA 515 Gr 60) with type 309 L as a barrier layer deposited by the SAW process. Welding heat input was changed in order to obtain different ferrite contents in the cladding. The clad samples were post-weld heat treated at 650°C for 50 and 200 h. The top layer of the cladding was removed and the specimens were then subjected to intergranular corrosion tests (ASTM A-262-75, practices A, B, C and E, viz. 10% oxalic acid electrolytic etch; ferric sulfate -50% sulfuric acid; 65% nitric acid and copper-copper sulfate -16% sulfuric acid tests) and controlled potential etching test.The study indicated that the ferrite content of the cladding decreases with increasing current. Ferrite transformed after PWHT (post weld heat treatment) was relatively more in claddings obtained with low heat input and containing high ferrite content in the as-clad condition. PWHT led to brittle fracture of high ferrite claddings (above 10 FN).The corrosion attack of ferrite was found to depend on environment. 65% nitric acid attacked ferrite preferentially, whereas in acid-ferric sulfate, ferrite was intact and austenite was attacked. No sample exhibited susceptibility to intergranular corrosion in the as-clad or PWHT conditions in the copper-copper sulfate -16% acid test. However, PWHT specimens with low ferrite contents (3.55 FN) exhibited grain boundary precipitation at the interface of two adjacent layers. In general, ferrite was found to be beneficial in controlling corrosion rates of clad metals after PWHT. Heat input, within the range studied, did not affect the corrosion rates significantly.

11 Ill.

Electronic Resource

0947-5117

Chemistry ; Polymer and Materials Science

Wiley InterScience Backfile Collection 1832-2000

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Einfluß des Ferritgehalts und der Wärmeeinbringung beim Schweißen auf die Beständigkeit austenitischer Auftragswerkstoffe gegen Spannungsrißkorrosion bei RaumtemperaturAuftragsschweißungen aus austenitischen nichtrostenden Stählen mit unterschiedlichen Ferritgehalten (FN 2, 4, 10 und 12) wurden durch Unterpulveraufschweißen von Blechen erhalten. Um den Einfluß der Wärmeeinbringung zu ermitteln, wurden die Auftragsschweißungen vom Grundmaterial getrennt und mittels WIG umgeschmolzen. Das Verhalten gegen Spannungsrißkorrosion wurde unter Verwendung von gekerbten Zugproben in 5 N Schwefelsäure + 0,5 N NaCl bei Raumtemperatur untersucht. Als Kriterium für die relative Spannungsrißkorrosionanfälligkeit wurde die Belastung gewählt, die innerhalb von 100 h zum Bruch der Proben führte. Der Einfluß des kathodischen Schutzes wurde durch Kontakt der Proben mit Zink untersucht.Die Ergebnisse zeigen, daß zunehmende Ferritgehalte die Widerstandsfähigkeit gegen Spannungsrißkorrosion verringern, wobei das WIG-umgeschmolzene Material höhere Beständigkeit als das unterpulvergeschweißte aufweist. Kathodischer Schutz verbessert die Widerstandsfähigkeit aller Proben. Die Rißbildung ist bedingt durch verformungsunterstützte Ferritauflösung und durch Spannungsrißkorrosion im Austenit, die wiederum durch einen Tunnelmechanismus hervorgerufen wird.

Austenitic stainless steel claddings with different ferrite contents (2, 4, 10, 12 FN) were obtained by the submerged are welding (SAW) strip cladding process. In order to study the effect of heat input the claddings were removed from the base plate and TIG remelted. Stress corrosion cracking (SCC) tests were carried out with notched tensile specimens in 5 N H2SO4 + 0.5 N NaCl at room temperature. A net-section stress required to break the specimen in 100 hours was taken as a criterion of relative SCC susceptibility. The effect of cathodic protection was studied by coupling the specimens with zinc.The results showed that increasing ferrite content decreases SCC resistance. TIG remelted material exhibited better SCC resistance than the SAW specimens. Cathodic protection improves the SCC resistance of all the specimens. Cracking was found to be due to strain-assisted ferrite dissolution and SCC in austenite. SCC in austenite was due to tunnelling mechanism.

10 Ill.

Electronic Resource

2018-04-21

American Chemical Society (ACS)

Chemistry and Pharmacology

1089-7550

AIP Digital Archive

Physics

Schottky diodes were formed on n-GaAs surfaces that had undergone furnace and scanned electron beam (SEB) heat treatments that are similar to those typically used for Ohmic contact formation. The diode parameters of heat-treated samples were inferior to those that were not heat treated. The interface-state density Dit, determined from Tseng and Wu's interfacial layer model, was found to exhibit a strong correlation with the heat treatments, with furnace-annealed samples exhibiting progressively larger Dit values than SEB annealed samples. The presence of a spin-on glass capping layer during heat treatment resulted in reduced Dit values. Photochemical passivation of the GaAs surface before Schottky metal deposition resulted in a reduction in the interface-state density. Controlled etching of a heat-treated GaAs surface revealed that the surface damage caused by heat treatments extends to about 500 nm. Elevated thermal aging studies of Schottky contacts show a monotonic increase in Dit with aging time, irrespective of surface preparation.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Electrical and optical spectroscopic studies of TiO2 anatase thin films deposited by sputtering show that the metastable phase anatase differs in electronic properties from the well-known, stable phase rutile. Resistivity and Hall-effect measurements reveal an insulator–metal transition in a donor band in anatase thin films with high donor concentrations. Such a transition is not observed in rutile thin films with similar donor concentrations. This indicates a larger effective Bohr radius of donor electrons in anatase than in rutile, which in turn suggests a smaller electron effective mass in anatase. The smaller effective mass in anatase is consistent with the high mobility, bandlike conduction observed in anatase crystals. It is also responsible for the very shallow donor energies in anatase. Luminescence of self-trapped excitons is observed in anatase thin films, which implies a strong lattice relaxation and a small exciton bandwidth in anatase. Optical absorption and photoconductivity spectra show that anatase thin films have a wider optical absorption gap than rutile thin films.

Electronic Resource

1471-4159

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Electronic Resource

1471-4159

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Electronic Resource

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

Fission counters have been developed indigenously, using 233U as a sensing material for reactor startup applications. The first model has a counting sensitivity of 0.003 cps/nv in the pulse mode, 1×10−15 A/nv in the dc mode, and 6.4×10−29 A2 Hz/nv in the Campbell mode. A more sensitive counter with about 75 mg of 233U showed an average sensitivity of 0.02 cps/nv. A proposal for 233U in-core miniature dc fission chambers is discussed. A design for high sensitivity (0.5 cps/nv) U-233 pulse counter with transmission line-type readout is also proposed. © 1996 American Institute of Physics.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

Novel ferroelectric bismuth vanadate, Bi2VO5.5 (BVO), thin films have been grown between lattice matched metallic LaNiO3 (LNO) layers deposited on SrTiO3 (STO) by the pulsed laser deposition technique. LNO/BVO/LNO/STO and Au/BVO/LNO/STO trilayer structures exhibited c-oriented (001) growth of BVO. LNO has been found to be a good metallic electrode with sheet resistance ∼20 Ω in addition to aiding c-axis oriented BVO growth. The dielectric constant, εr of LNO/BVO/LNO/STO, at 300 K was about 12. However, when an Au electrode was used on top of BVO/LNO/STO film, it showed a significant improvement in the dielectric constant (εr=123). The ferroelectric properties of BVO thin films have been confirmed by hysteresis behavior with a remnant polarization, Pr=4.6×10−8 C/cm2 and coercive field, Ec=23 kV/cm at 300 K.

Electronic Resource

1365-2044

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Electronic Resource

1360-0443

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Psychology

Background  In spite of a perception that alcohol use is rampant in Nepal, there has been no survey to assess the extent of alcohol dependence in the country.Aims  (i) To assess prevalence of alcohol dependence in the community of Dharan and (ii) to correlate this with various socio-demographic characteristics.Design  The CAGE questionnaire was administered to all adult individuals in houses selected randomly in the township of Dharan.Findings  Among 2344 adults assessed, the prevalence of alcohol dependence was found to be 25.8%. The prevalence of alcohol dependence increased with age to peak in the age group 45–54 years and was more than twice as common in men as in women. Also, alcohol dependence was more common among those with lower level of education, widowers and divorcees and those belonging to the Matwali community. The extent of dependence was influenced by socio-cultural sanctions.Conclusions  The prevalence of alcohol dependence is too high for comfort in Dharan, a town in eastern Nepal. There is an urgent need to formulate a policy for substance abuse in the country taking into account the findings of this study.

Electronic Resource

0003-9861

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Chemistry and Pharmacology

Physics

Electronic Resource