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63.
Sayed S. Abd El-Rehim Abd-Halim M. Abd El-Halim Magda M. Osman 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1985,35(8):415-425
The electrodeposition of cobalt-nickel alloys has been studied from ammoniacal single-complex baths containing 5–50 CoSo4·7H2O, 5–50 NiCl2·46H2O, 20–50 g dm?3 (NH4)2SO4 and 250–350 cm3 dm?3 NH4OH (20.5% solution). The effects of the plating current density and the concentrations of the bath constituents on the cathodic polarisation, current efficiency and composition of the alloy were investigated. A wide range of alloy compositions with a current efficiency of 60–80% could be obtained from the main baths examined. The alloy plating system interchanged between the normal and the anomalous types depending upon the plating current density and the concentration of NH+4 ion in the bath. Electron microscopic and X-ray diffraction studies proved that the structure of the electrodeposited alloy was controlled by the alloy composition. 相似文献
64.
Shear-induced orientation and the relaxation of orientation after the cessation of shear in 45 and 50 wt% solutions of cholesteric hydroxypropylcellulose (HPC) in m-cresol have been studied in situ by infrared spectroscopy and polarised microscopy. The shearing experiments were conducted at 30-80 °C at shear rates of 1-300 s−1, which covered the director tumbling, wagging and a small part of the steady-state shear rate regimes. The steady-state order parameter was proportional to the shear rate and the proportionality constant increased with increasing HPC concentration and decreasing temperature. The concentrated solutions studied showed steady-state alignment even in the tumbling regime. Three different shear-rate regions with different behaviours of the solutions after the cessation of shear were found in these concentrated HPC solutions. At low shear rates (1-5 s−1, referring to the 50% HPC solution) the polymer remained isotropic during shear but became gradually more oriented a few minutes after the cessation of shear, an observation that was substantiated by polarized microscopy. The order parameter reached a final plateau value and stayed constant at this level for long periods of time (∼24 h). At intermediate shear rates (from 5 to 50 s−1 for the 50% HPC solution), a detectable order parameter was recorded at steady shear and, after the cessation of shear, the structure returned to an almost isotropic state within a few minutes, after which the orientation gradually started to increase to approach a plateau value after about 150 min. At even higher shear rates (∼100 s−1 for to the 50% HPC solution), the initial steady shear order parameter relaxed to an almost isotropic state and remained constant at this level for time periods extending up to 24 h. 相似文献
65.
Wolfgang E.G. Hansal Barbara Tury Magda Lakatos Varsányi Wolfgang Kautek 《Electrochimica acta》2006,52(3):1145-1151
Fundamental electrochemical properties of electrolyte systems are the prerequisite for the development of a successful pulse deposition process. Three different electrolyte systems for the galvanic deposition of nickel cobalt alloys (chloride, Watts and sulfamate type) were investigated in order to reveal underlying deposition mechanisms and rate determining factors. The electrochemical experiments were supported by X-ray fluorescence analyses of the alloy composition in dependence on the current density and the type of bath. A special focus was set on the investigation of the passive (oxide) layer formation by the anodic pulses.The choice of electrolyte system strongly influences the reaction mechanism and thus the alloy deposition. Also the cobalt content within the deposited layer varied strongly in dependence on the electrolyte system used. While sulfamate and Watts baths show an ability for passive layer formation, the chloride bath exhibits a lower proneness to passivation, accompanied by pit formation 相似文献
66.
Magda A. El-Shahawy 《Polymer Bulletin》1993,31(2):199-203
Summary The optical absorption spectra of Co-doped PVA thick films (1 mm) of different concentrations from 0.0 to 30% CoCl2 are obtained at room temperature in the range 190–900 nm. Cobalt (II) is found to exist only in octahedral coordination for concentrations up to 10% with an asymmetrical absorption band located at 511 nm and shifted to longer weve length with increasing CoCl2 content. For higher concentration (>10%) the coexistence of both octahedral and tetrahedral coordinations is indicated by the appearance of a new structured broad band centered at 665 nm. Variations in the obtained spectra suggest a tendency to higher degree of ordering in the amorphous regions of the polymer structure by CoCl2 addition. 相似文献
67.
Ahmed M. HassanAuthor Vitae Magda El-Shenawee Author Vitae 《Journal of Parallel and Distributed Computing》2011,71(7):1011-1023
The diffusion-drift algorithm for calculating the electric signals of growing breast cancerous cells is parallelized based on the Message Passing Interface technique. The parallelized algorithm is analyzed with emphasis on the existing bottlenecks. The model involves the solution of several systems of equations to calculate the biopotentials and ion concentration gradients generated by MCF-7 cells, the most studied breast cancer cell line. The Portable, Extensible Toolkit for Scientific Computation library is investigated for the parallel solution of these systems of equations. The results show that the optimum solver for the biopotential system of equations is the Enhanced Bi-Conjugate Gradient Stabilized (L) solver. Also, it is found that the optimum pre-conditioner is the Additive Schwarz Method coupled with the drop tolerance Incomplete LU factorization. A maximum overall speed up of 15 was achieved using 56 processors with an efficiency of 27%. The electrophysiological activity of a tumor a third of a millimeter in size with just over a thousand cancerous cells is simulated. The numerical values of the biopotential could indicate to breast cancer in very early stages. 相似文献
68.
A. P. Stepovik G. V. Mokichev E. P. Magda S. V. Kiryushkin A. N. Kozikov A. L. Semkov A. V. Kurochkin A. V. Lukin D. V. Khmel’nitskii V. P. Popov 《Instruments and Experimental Techniques》2005,48(1):109-111
The use of an updated accelerator of the -12 neutron generator as a high-current implanter of hydrogen ions (protons and deuterons) with energies of 175–210 MeV into wafers made of crystalline silicon is described. The ion-beam scanning system used ensured nonuniformity in the irradiation of wafers with a diameter of 100 mm of <10%, which allowed the production of silicon-on-insulator wafers by the hydrogen splitting technique. The required particle fluence was 1017 cm–2. A slight refinement of the setup allows wafers with diameters of up to 200 mm to be irradiated. The design features of the setup as they apply to different temperature conditions (down to a temperature close to that of liquid nitrogen) of the irradiation of 100-mm-diameter wafers are described.Translated from Pribory i Tekhnika Eksperimenta, No. 1, 2005, pp. 126–129.Original Russian Text Copyright © 2004 by Stepovik, Mokichev, Magda, Kiryushkin, Kozikov, Semkov, Kurochkin, Lukin, Khmelnitskii, Popov. 相似文献
69.
Nelson D. Rodríguez‐Marin Aylin A. Figueroa‐Chaverra Mayerly A. Snchez‐Jimnez Vanessa Orozco‐Orrego Constanza Bohrquez‐Orozco Omar R. García Magda I. Pinzn Leidy T. Snchez Cristian C. Villa 《Journal of texture studies》2019,50(2):148-154
Growing interest in processed frozen products with similar characteristics to natural products has generated the study of new products in the food industry field. The characteristics of each matrix, the process of elaboration, composition, and structure of the additives and the interactions amongst these modify the food's texture, structure, physical and sensory properties and, hence, interfere directly with consumer acceptance. This research studied the effect of adding cryoprotectors during frozen storage on the rheological, physicochemical, structural, and microbiological properties in a Mafafa‐quinoa‐olive oil puree. To carry out the study, the rheological properties were determined through dynamic oscillatory tests and in steady state; likewise, the physicochemical properties (humidity, color, pH, and syneresis) were analyzed. Regarding physicochemical properties, the humidity content in the purees formulated varied between 57 and 74%, without important variation (p > .05) with respect to the formulation, however, in the storage during the freezing/thawing process, this parameter diminished in greater proportion in those purees containing carrageenan as cryoconservant. Both the addition of cryoconservants and the storage time affected significantly (p < .05) the puree's syneresis, with the degree of exudation being lower in the formulation containing xanthan gum at 1% w/w. During the freezing/thawing process, decreased apparent viscosity was noted. Additionally, the analysis of the viscoelastic properties of the purees evidences that already described, given that a significant effect (p < .05) was observed of the formulation of purees in the elastic component G′, in contrast with a notable decrease in the viscous component G″. 相似文献
70.
Magda Corgneau Claire Gaiani Jeremy Petit Yoana Nikolova Sylvie Banon Léa Ritié-Pertusa Doan Thanh Lam Le Joël Scher 《International Journal of Food Science & Technology》2019,54(6):2132-2140
Influence of diverse botanical sources (wheat, maize, waxy maize, cassava, potato, rice or waxy rice) on in vitro native starch digestibility has been investigated. Physicochemical properties (chemical composition, particles size and shape, surface features) of starch granules were determined with a view to explaining digestibility differences between samples. Rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS) contents were measured according to Englyst method. Potato starch was shown to be composed of large rounded granules having smooth surfaces, which explains its slow enzymatic breakdown. Potato starch displayed the highest RS (86%) content and the lowest RDS content (9.9%). Since RS positively influences health and SDS may result in cell, tissue and/or organ damages, potato starch is an ideal starch nutrient. Conversely, waxy rice starch was rich in amylopectin and displayed small diameters and angular shapes, which are both known to facilitate enzymatic starch hydrolysis. It exhibited a near-zero RS content (0.9%) and a high RDS fraction (60%). According to this study, potato starch exhibited the best nutrient profile, followed up in this order by cassava, waxy maize, wheat, maize and waxy rice starches. 相似文献