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Solute redistribution has been a long-term interest in solidification theoretical study, but its effect on growth rate during solidification is still not completely clear. Models that descript the relationship between growth rate and the alloy concentration remain controversial both qualitatively and quantitatively. This work theoretically analysed and investigated the solute redistribution and its effect on constitutional undercooling during solidification. Systematic analysis on the interaction behaviour between the solid/liquid interface movement and the solute distribution has been performed to clarify the effect of constitutional undercooling on growth rate of solid during solidification. It is demonstrated that the growth rate of crystals conversed to the alloy concentration and the relationship could be quantitatively calculated by the present model by introduction of the interface retardation.

Fractal growth patterns of polyaniline were developed during electropolymerization of aniline using the surfactants sodium dodecyl sulphate (NaDS) and NaDS containing cetyl trimethyl ammonium bromide (CTAB). Growth kinetics was studied and electric potential oscillations were monitored as a function of time. On addition of CTAB polymer growth was inhibited due to coordination of CTAB with the growing polyaniline chain. The average particle size of the polymer aggregate obtained from aniline-NaDS-H₂O system was ~150 nm as evident by Transmission Electron Microscopy (TEM) results. Polymer aggregates were characterized by electrical conductivity measurements, X-ray diffraction (XRD) and Thermogravimetric (TG) studies. An interaction between NaDS and aniline was observed in the absence of electric field as evident by (i) electrical conductivity of aqueous solution of NaDS in the absence and presence of aniline, and (ii) their crystallization patterns on microslides. A mechanism for the development of fractal patterns and electrical potential oscillations is proposed on the basis of diffusion limited aggregation process.

Intermetallic formation at 425°C in the aluminum–copper system has been studied by scanning electron microscopy using welded diffusion couples. Several Al–Cu phases predicted by the equilibrium phase diagram of the elements and voids taking place in the diffusion zone have been detected in the couples. The predominant phases were found to be Al₂Cu₃ and the solid solution of Al in Cu, α. The growth of the intermetallic layer obeyed the parabolic law.

The growth kinetics of the solid solution phase of aluminum in copper in diffusion couples of pure aluminum and copper has been investigated at 425°C using a scanning electron microscope. In the initial stage, the phase layer growth was found to obey the parabolic law, indicating that the rate-controlling process is diffusion. At longer times, the growth rate deviates from the kt^-1/2 behavior of the early stage.

In this work, we discuss the growth of dilute InAsBi nanostructures grown by metalorganic vapor phase epitaxy on GaAs substrates. The surface morphology of InAsBi nanostructures is carefully investigated, as a function of the growth temperature, by scanning electronic microscopy and atomic force microscopy. (004) High-resolution X-ray diffraction configuration has been used to characterize the crystalline quality and Bi incorporation in the InAsBi films. Low temperature and low Bi flow favor the formation of elongated nanostructures during growth. We give a quantitative description of the elemental processes for the formation of these nanostructures. Our description is based on the Tersoff and Tromp theoretical model.

The microstructure resulting from diffusion reactions, at solid-state temperatures, in Ni/Sn couples has been studied by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). The Ni₃Sn₄ phase was the only reaction product which formed in the couples at temperatures from 150${}^{\circ }$C to 220${}^{\circ }$C. The growth kinetics of Ni₃Sn₄ layer followed the parabolic law with an apparent activation energy of 104kJmol${}^{-1}$. The effect of the atmosphere on the microstructure of the interfacial layer was investigated at 220${}^{\circ }$C for a pressure of 10${}^{-8}$atm. A decrease in the growth rate of the phase layer was observed.

It is believed that carbon nanotubes were not able to grow on silicon substrates by chemical vapor deposition from a mixture of ferrocene and xylene. This is because iron particles (formed by the decomposition of ferrocene) reacted quickly with silicon to form a discontinuous layer (> 100 nm) of FeSi₂ and Fe₂SiO₄ particles. We report, in this letter, that by controlling the growth kinetics, aligned carbon nanotubes could be grown on pristine silicon substrates. The reason is that appropriate growth conditions could slow down and suppress the reaction within the very surface region to form an almost continuous thin layer (< 10 nm) of Fe₂SiO₄ particles; thus preventing further reaction and leaving a number of iron particles still active to catalyze the growth of carbon nanotubes. The structure and field emission properties of the nanotubes were also investigated.

Spherulite is an important crystal growth form in many organic and inorganic substances. In the sol-to-gel transition of the N-lauroyl-L-glutamic acid di-n-butylamide (GP-1)/propylene glycol (PG) system, the formation of spherulitic fiber network was observed in situ by optical microscopy. The growth mechanism of the spherulite in the gelation process was examined quantitatively. A constant growth rate along the radial direction of the spherulite was ascribed to the surface kinetics controlling mechanism, in which a constant supersaturation throughout the spherulitic growth may be induced by the topological structure of the densely branching morphology in this gel network. Our results also indicate that the engineering of a fiber gel network can be attained via crystallization strategies, since spherulitic growth is a typical example that construction of supramolecular structure occurs as a consequence of the crystallization from dilute solutions.

Nickel oxide (NiO) nanoparticles were synthesized by calcination at 400°C to 700°C for 8 h of the precursor obtained via mechanochemical reaction of Ni(NO₃)₂ ⋅ 6H₂O with citric acid as a dispersant. The nanoparticles were characterized by thermogravimetric-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The kinetics of different surfaces of the nanocrystals under nonisothermal conditions was investigated. The activation energies for different lattice planes of NiO nanoparticles were determined using the Arrhenius equation, revealing their preferred orientation. The growth of NiO obeyed the general theory that nanoparticles with the largest surface energy tend to form. XRD data reveal that the NiO nanoparticles possess preferred (111) or (200) orientations that reflect their complex activity. The nature of preferred growth orientation was found to be negative diffusion activity among different lattice surfaces, which indicates that oxygen atoms diffuse from low oxygen concentration on the lattice surface to high concentration on the lattice surface.

In this research, the simultaneous growth of Al₃Ni₂ and Al₃Ni on nanocrystalline nickel was investigated. Nanocrystalline nickel samples with mean grain size of about 25 nm were prepared by direct current electroplating. The samples were aluminized for different durations by pack cementation method at 500, 550 and 600 °C. The aluminide phases were identified by SEM, EDS and XRD. In contrast to reported results suggesting the formation single layer of Al₃Ni₂ phase on coarse grained nickel, it was observed that long time aluminizing of nanocrystalline nickel resulted in the formation and simultaneous growth of two distinct layers of Al₃Ni₂ and Al₃Ni phases. The growth of both phases followed the parabolic growth kinetics, but the growth rate constant of Al₃Ni₂ was much greater than Al₃Ni layer. Also, the simultaneous growth of Al₃Ni₂ and Al₃Ni was modeled. Based on this model, the activation energy of the coating growth (total Al₃Ni₂ and Al₃Ni layers) was determined as about of 178 kJ/mol.

The microbial strains used for decontamination of different origin wastewater should not only be highly active to one of the contaminants but they should also be resistant enough to the remainder. Their resistance can be ensured by the degradation activity of the strains used towards most of the waste products present in the wastewater. Trichosporon cutaneum R57 is known as an effective biodegradant able to utilize and thus remove a number of toxic aromatic compounds from the environment. The present paper deals with processes of degradation and utilization of monohydroxyl derivatives of phenol (resorcinol, catechol and hydroquinone), as well as some of the most toxic aromatic pollutants of the environment like 2,6 - dinitrophenol, α-methylstyrene and acetophenone. The basic kinetic parameters for the biodegradation of the listed above compounds are reported. The highest initial concentrations which could be degraded by the investigated strain were as follow: resorcinol – 1.6 g/l; catechol – 1.3 g/l; hydroquinone – 1.2 g/l; 2,6-dinitrophenol – 0.7 g/l; α-methylstyrene and acetophenone – 0.5 g/l. The inhibition coefficients were calculated according to the Haldane-kinetics. The results obtained certainly proved the ability of strain T. cutaneum R57 to degrade wide range toxic contaminants present in industrial production wastewaters.