Photocatalytic inactivation of Escherischia coli and Pichia pastoris with combustion synthesized titanium dioxide

The photocatalytic inactivation of Escherischia coli and Pichia Pastoris was studied with combustion synthesized titanium dioxide photocatalysts Three different combustion synthesized (CS) catalysts were used viz CS-TiO2 1% Ag substituted in TiO2 and 1% Ag impregnated in TiO2 All the combustion synthesized catalysts showed higher activity as compared to the activity observed with commercial Degussa P-25 TiO2 The effect of various parameters like catalyst loading different catalysts and initial cell concentration was studied At the optimum loading 1% Ag impregnated TiO2 showed the maximum efficiency and complete inactivation of both the microorganisms was observed within an hour of irradiation The morphology of inactivated cells was studied by inverted microscope and SEM From the images obtained it was hypothesized that damage to the cell wall was the main cause of cell inactivation The initial cell concentration had a prominent effect on the inactivation At a low initial cell concentration the complete inactivation of E cob and P pastoris was observed within 10 and 20 min respectively This shows that P pastoris has a stronger resistance towards photocatalytic inactivation than E cols The inactivation reactions were modeled with power law kinetics The order of reaction in case of E colt and P pastoris were determined as 1 20 and 1 08 respectively (C) 2010 Elsevier B V All rights reserved

Characterisation of dynamic recrystallisation in nickel using processing map for hot deformation

The hot deformation behaviour of polycrystalline nickel has been characterised in the temperature range 750-1200-degrees-C and strain rate range 0.0003-100 s-1 using processing maps developed in the basis of the dynamic materials model. The efficiency of power dissipation, given by [2m/(m + 1)]. where m is the strain rate sensitivity, is plotted as a function of temperature and strain rate to obtain a processing map. A domain of dynamic recrystallisation has been identified, with a peak efficiency of 31% occurring at 925-degrees-C and 1 s-1. The published results are in agreement with the prediction of the processing map. The variations of efficiency of power dissipation with temperature and strain rate in the dynamic recrystallisation domain are identical to the corresponding variation of hot ductility. The stress-strain curves exhibited a single peak in a single peak in the dynamic recrystallisation domain, whereas multiple peaks and 'drooping' stress-strain curves were observed at lower and higher strain rates, respectively. The results are explained on the basis of a simple model which considers dynamic recrystallisation in terms of rates of interface formation (nucleation) and migration (growth). It is shown that dynamic recrystallisation in nickel is controlled by the rate of nucleation, which is slower than the rate of migration. The rate of nucleation itself depends on the process of thermal recovery by climb, which in turn depends on self-diffusion.

dc reactive magnetron sputtering of titanium‐structural and optical characterization of TiO2 films

This paper deals with the reactive sputtering of titanium in an argon and oxygen mixture. The variation in cathode potential as a function of oxygen partial pressure has been explained in terms of cathode poisoning effects. The titania films deposited during this process have been studied for their structural and optical characteristics. The effect of substrate temperature (from 25 to 400 °C) and annealing (from 250 to 700 °C) on the packing density, refractive index, extinction coefficient, and crystallinity has been investigated. The refractive index varied from 2.24 to 2.46 and extinction coefficient from 2.6 × 10-3 to 10.4× 10-3 at 500 nm as the substrate temperature increased from 25 to 400 °C. The refractive index increased from 2.19 to 2.35 and extinction coefficient changed from 3.2× 10-3 to 11.6 × 10-3 at 500 nm as the annealing temperature was increased from 250 to 700 °C. Anatase and rutile phases have been observed in the films deposited at 400 °C substrate temperature and annealed at 300 °C. The changes in the optical constants at higher substrate temperature have been attributed to an increase in packing density, oxygen content, and crystallinity of the films.

Electroless nickel hydroxide: synthesis and characterization

An electroless method of nickel hydroxide synthesis through the complexation-precipitation route which yields a fine particle material having a specific surface area of 178 m2 g–1 has been described. The morphology of this material as revealed by electron microscopy is distinctly different from the turbostratic nature of electrosynthesized nickel hydroxide. While the long range structure as shown by the X-ray diffraction pattern is similar to that of beta-Ni(OH)2, the short range structure as revealed by infrared spectroscopy incorporates characteristics similar to that of agr-Ni(OH)2. Cyclic voltammetry studies show that the electroless nickel hydroxide has a higher coulombic efficiency (>90%), a more anodic reversible potential and a higher degree of reversibility compared to the electrosynthesized nickel hydroxide and conventionally prepared nickel hydroxide.

An unusual anti-markovnikov hydration of alkenes with titanium(III) tetrahydroborates

Titanium(III) tetrahydroborate formed by the reaction of titanium tetrachloride and benzyltriethylammonium borohydride (1:4) reacts with alkenes in dichloromethane (-20-degrees-C) very readily to yield directly the corresponding alcohols in excel lent yields after a simple aqueous work up.

Interaction of solid films of C60 and C70 with nickel

Interaction of varying coverages of Ni metal with solid films of C60 and C70 has been investigated by UV and X-ray photemission spectroscopy. The shifts in the valence bands of C60 (as well as of C70) with increasing Ni coverage accompanied by a shift of the C is level of the fullerene to lower binding energies suggest charge-transfer from the metal to the fullerene as in transition metal complexes of π-systems.

Microstructural features of flow instability in α-titanium cylinders under high strain rate compression at 25°C to 400°C

Cylindrical specimens of commercial pure titanium have been compressed at strain rates in the range of 0.1 to 100 s-1 and temperatures in the range of 25-degrees-C to 400-degrees-C. At strain rates of 10 and 100 s-1, the specimens exhibited adiabatic shear bands. At lower strain rates, the material deformed in an inhomogeneous fashion. These material-related instabilities are examined in the light of the ''phenomenological model'' and the ''dynamic materials mode.'' It is found that the regime of adiabatic shear band formation is predicted by the phenomenological model, while the dynamic materials model is able to predict the inhomogeneous deformation zone. The criterion based on power partitioning is competent to predict the variations within the inhomogeneous deformation zone.

Processing maps for hot working of Cu-Ni-Zn alloys. Part I - Alpha-nickel silver

The constitutive behaviour of agr — nickel silver in the temperature range 700–950 °C and strain rate range 0.001–100 s–1 was characterized with the help of a processing map generated on the basis of the principles of the ldquodynamic materials modelrdquo of Prasadet al Using the flow stress data, processing maps showing the variation of the efficiency of power dissipation (given by 2m/(m+1) wherem is the strain-rate sensitivity) with temperature and strain rate were obtained, agr-nickel silver exhibits a single domain at temperatures greater than 750 °C and at strain rates lower than 1s–1, with a maximum efficiency of 38% occurring at about 950 °C and at a strain rate of 0.1 s–1. In the domain the material undergoes dynamic recrystallization (DRX). On the basis of a model, it is shown that the DRX is controlled by the rate of interface formation (nucleation) which depends on the diffusion-controlled process of thermal recovery by climb. At high strain rates (10 and 100s–1) the material undergoes microstructural instabilities, the manifestations of which are in the form of adiabatic shear bands and strain markings.

Processing maps for hot working of Cu-Ni-Zn alloys Part II Alpha-Beta nickel silver

The constitutive behaviour of agr-beta nickel silver in the temperature range 600�850 °C and strainrate range 0.001�100s�1 was characterized with the help of a processing map generated on the principles of the dynamic materials model. On the basis of the flow-stress data, processing maps showing the variation of the efficiency of power dissipation (given by [2m/(m+1)], wherem is the strain-rate sensitivity) with temperature and strain rate were obtained, agr-beta nickel silver exhibits a single domain at temperatures greater than 700 °C and at strain rates lower than 1 s�1 with a maximum efficiency of power dissipation of about 42% occurring at about 850 °C and at 0.1 s�1. In the domain, the agr phase undergoes dynamic recrystallization and controls the deformation of the alloy, while the beta phase deforms superplastically. Optimum conditions for the processing of agr-beta nickel silver are 850 °C and 0.1 s�1. The material undergoes unstable flow at strain rates of 10 and 100 s�1 and in the temperature range 600�750 °C, manifestated in the form of adiabatic shear bands.

Stabilization of α-nickel hydoxide in the presence of organic additives: chemical route to bulk synthesis

Organic molecules such as glucose or lactose mediate the synthesis and stabilize alpha-nickel hydroxide in a simple precipitation reaction, while, in the absence of these additives, beta-nickel hydroxide is formed. The additives are not incorporated in the product phase.

Temperature dependence of hydrogen evolution reaction on nickel oxide electrode in sealed nickel/cadmium cells

The impedance of sealed nickel/cadmium cells around a cell e.m.f. of 0.0 V was measured at five different temperatures between � 10 and +30 °C. The results show that the behaviour is similar at all temperatures. Based on the experimental results, the relation between charge-transfer resistance (Rct) and temperature (T) has been established for the Volmer reaction. Further, the value of cathodic transfer coefficient (?) has been estimated.

Texture evolution and operative mechanisms during large-strain deformation of nanocrystalline nickel

The large-strain deformation of nanocrystalline nickel was investigated at room temperature and cryogenic (liquid N-2) temperature. Deformation mechanisms ranging from grain boundary sliding to slip, operate due to a wide distribution of grain sizes. These mechanisms leave their finger print in the deformation texture evolution during rolling of nanocrystalline nickel. The occurrence and severance of different mechanisms is understood by a thorough characterization of the deformed samples using X-ray diffraction, X-ray texture measurements, electron back-scattered diffraction and transmission electron microscopy. Crystal plasticity-based viscoplastic self-consistent simulations were used to further substantiate the experimental observations. Thus, a comprehensive understanding of deformation behavior of nanocrystalline nickel, which is characterized by simultaneous operation of dislocation-dominated and grain boundary-mediated mechanisms, has been developed.

Texture evolution in commercially pure titanium after warm equal channel angular extrusion

Texture development in commercially pure titanium during equal channel angular extrusion (ECAE) through Routes A, Be and C has been studied up to three passes at 400 C. Textures were measured using X-ray diffraction, while the microstructural analyses were performed using electron back-scattered diffraction as well as transmission electron microscopy. Occurrences of dynamic restoration processes (recovery and recrystallization) were clearly noticed at all levels of deformations. Finally, the textures were simulated using a viscoplastic polycrystal self-consistent (VPSC) model. Simulations were performed incorporating basal, prismatic and pyramidal slip systems as well as tensile and compressive twinning. The simulated textures corroborate well with experimental textures in spite of the occurrence of dynamic restoration processes. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

The Determination of the Surface Tensions of Liquid-Iron, Nickel and Iron-Nickel Alloys using the electromagnetic Oscillating Droplet Technique

An oscillating droplet method combined with electromagnetic levitation has been applied to determine the surface tensions of liquid pure iron, nickel and iron-nickel alloys as a function of the temperature. The natural frequency of the oscillating droplet is evaluated using a Fourier analyser. The theoretical background of this method and the experimental set-up were described, and the influence of magnetic field strength was also discussed. The experimental results were compared with those of other investigators and interpreted using theoretical models (Butler's equation, subregular and perfect solution model for the surface phase).

The Determination of the Surface Tensions of Nickel Sulfur Alloys using the Electromagnetic Oscillating Droplet Technique

An oscillating droplet method combined with electromagnetic levitation technique has been applied to determine the surface tensions of liquid nickel sulphur alloys as a function of the temperature and composition. The natural frequency of the oscillating droplet is evaluated using a Fourier analyser, and the influence of magnetic field strength on the surface tension was considered. Furthermore, the applicability of Butler's equation and subregular solution model for the surface was shown to predict the surface tension of the systems containing the surface active elements.