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11.
Zakaria Hassan Abdelwahab Talaat A. Elgarf Abdelhalim Zekry 《Information Security Journal: A Global Perspective》2020,29(6):341-365
ABSTRACT Confidentiality and integrity processes are based on SNOW and ZUC algorithms. These standardized algorithms are designed by the 3rd Generation Partnership Project (3GPP) for advanced mobile communication systems. Each algorithm has two S-boxes in its nonlinear layer structure. This paper proposes three different approaches to enhance the security level of both algorithms. The first approach aims to select the best combination of two S-boxes in the nonlinear part of each algorithm. Results showed that the best randomness properties are achieved by combining the Feistel structure (S1-box) and Rijndael (S2-box) in the SNOW algorithm and New Rijndael (S1-box) and Rijndael (S2-box) in the ZUC algorithm. The second approach aims to increase the nonlinearity and complexity of these algorithms by selecting a strong S-box to cascade the best-existing two S-boxes for both algorithms. The third approach is an extension of the former, based on a dynamic reform of such S-boxes as a function of the “Authentication Token” to increase the computational complexity of the upgraded two algorithms. These proposed upgrades are simulated by C language and tested successfully for their statistical properties using the standard NIST SP 800-22 test suite. 相似文献
12.
Multimedia Tools and Applications - Recently, many concepts in technology has been changed. According to the digital transformation trends, Internet of Things (IoT) represents an interested... 相似文献
13.
Kanaan K. Abdul-Halim M. Talaat M. Balba Eric Senior 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1988,43(2):131-137
The three major polymeric components of Scots Pine sawdust–lignin, hemicellulose and cellulose–represent potential substrates for methanogenic fermentation although, in the absence of physicochemical pretreatment, low digestibility was demonstrated even after protracted incubation (18 months). Acid (H2SO4) and alkali (NaOH) pretreatments mediated different effects although, in general, the rates and percent solubilisations increased with concentration, temperature, pressure and time, either singly or in combination. Individual methanogenic fermentations with the hydrolysates and residual solids showed that although 3.3% more methane resulted from the H2SO4 hydrolysate than the corresponding NaOH hydrolysate, in total, 7% more methane was generated from the two alkali fractions than from the corresponding acid fractions. The results thus exemplified that choice of a specific physicochemical strategy must be made in conjunction with the expected yield from the selected fraction(s). 相似文献
14.
Auger-spectroscopic investigations into pitting corrosion of FeCr, FeMo and FeCrMo alloys A single pit was produced on binary iron-chromium (Fe17Cr), iron-molybdenum (Fe1Mo, Fe3Mo, and Fe5Mo) and ternary iron-chromium-molybdenum alloys (Fe17CrxMo, x = 1, 3, 7 wt.%) in 0.5 M H2SO4 with Cl? additions (0.02 to 0.08 molar) at room temperature. Compositional changes at the bottom of the pit and in the surrounding passive film were determined using high resolution Auger-Electron Spectroscopy (AES). The chromium and molybdenum content of the passive layers are not changed in the presence of Cl? and there is no incorporation of chlorine in the passive film as long as the films were formed in a chlorine-free electrolyte and Cl? was added later. At the bottom of the pits salt films could be determined in all cases after removing the electrolyte with filter paper. These salt films are strongly enriched in chromium, molybdenum and chlorine. The salt film was not detectable for Fe-Cr after rinsing the samples with distilled water, whereas in the case of molybedenum additions the salt film could not be washed away with water. 相似文献
15.
16.
Nanocrystalline titanium films of different thicknesses, sputtered on sapphire substrates, were charged electrochemically with hydrogen. Hydrogen absorption and the thermodynamics of the nanocrystalline Ti–H thin film system were studied using electromotive force (EMF) measurements. The phase boundaries obtained from the EMF–pressure–concentration curves were confirmed by X-ray diffraction, complemented by in situ stress measurements during hydrogen charging. The change in the stress increase with hydrogen concentration was found to be in good agreement with the obtained phase boundaries. In comparison to bulk Ti–H system, considerable changes, such as shifted phase boundaries, and narrowed and sloped miscibility gaps, were observed in Ti–H thin films. These changes vary among the films of different crystalline orientation and are attributed to both microstructural effects and stress contributions. The influence of the initial crystallographic growth orientation of Ti films on the measured thermodynamic isotherms, phase transitions and stress development is discussed in detail. 相似文献
17.
Zhibiao Xing Xinhua Zhu Jianmin Zhu Zhiguo Liu Talaat Al‐Kassab 《Journal of the American Ceramic Society》2014,97(7):2323-2330
Multiferroic Bi1?xLaxFeO3 [BLFO (x)] ceramics with x = 0.10–0.50 and Mn‐doped BLFO (x = 0.30) ceramics with different doping contents (0.1–1.0 mol%) were prepared by solid‐state reaction method. They were crystallized in a perovskite phase with rhombohedral symmetry. In the BLFO (x) system, a composition (x)‐driven structural transformation (R3c→C222) was observed at x = 0.30. The formation of Bi2Fe4O9 impure phase was effectively suppressed with increasing the x value, and the rhombohedral distortion in the BLFO ceramics was decreased, leading to some Raman active modes disappeared. A significant red frequency shift (~13 cm?1) of the Raman mode of 232 cm?1 in the BLFO ceramics was observed, which strongly perceived a significant destabilization in the octahedral oxygen chains, and in turn affected the local FeO6 octahedral environment. In the Mn‐doped BLFO (x = 0.30) ceramics, the intensity of the Raman mode near 628 cm?1 was increased with increasing the Mn‐doping content, which was resulted from an enhanced local Jahn–Teller distortions of the (Mn,Fe)O6 octahedra. Electron microscopy images revealed some changes in the ceramic grain sizes and their morphologies in the Mn‐doped samples at different contents. Wedge‐shaped 71° ferroelectric domains with domain walls lying on the {110} planes were observed in the BLFO (x = 0.30) ceramics, whereas in the 1.0 mol% Mn‐doped BLFO (x = 0.30) samples, 71° ferroelectric domains exhibited a parallel band‐shaped morphology with average domain width of 95 nm. Dielectric studies revealed that high dielectric loss of the BLFO (x = 0.30) ceramics was drastically reduced from 0.8 to 0.01 (measured @ 104 Hz) via 1.0 mol% Mn‐doping. The underlying mechanisms can be understood by a charge disproportion between the Mn4+ and Fe2+ in the Mn‐doped samples, where a reaction of Mn4+ + Fe2+→Mn3+ + Fe3+ is taken place, resulting in the reduction in the oxygen vacancies and a suppression of the electron hopping from Fe3+ to Fe2+ ions effectively. 相似文献
18.
Esomeprazole was labeled with 99m Tc in high (up to ~98.0%) radiochemical yield. The optimum conditions are as follows: pH 8, 50 μg of SnCl2·2H2O, 30 min, and 2 mg of the substrate. The complex is stable for 8 h. The reaction mixture was separated by gel chromatography using such eluents as NaCl solution and, phosphate, citrate, and carbonate buffer solutions. Free 99m TcO 4 – and the complex were also efficiently separated by reversed-phase HPLC, paper chromatography, and electrophoreses. Intravenous biodistribution studies of 99m Tc-esomeprazole complex showed high uptake in the stomach ulcer, reaching about 30.5% ID/g at 1 h post injection. Such a high 99m Tc-esomeprazole uptake makes this agent promising for stomach ulcer imaging. 相似文献
19.
Jamil K. Salem Talaat M. Hammad S. Kuhn Mohammed Abu Draaz Naser K. Hejazy R. Hempelmann 《Journal of Materials Science: Materials in Electronics》2014,25(5):2177-2182
Cobalt-doped Zinc sulfide (ZnS) nanoparticles were prepared by a simple chemical method using alkyl hydroxyl ethyl dimethyl ammonium chloride (YH) as capping agent. The structural and optical properties of prepared cobalt-doped ZnS nanoparticles have been characterized. X-ray diffraction patterns and transmission electron microscope images reveal pure cubic ZnS phase with size of about 5–2 nm for all cobalt-doped ZnS nanoparticles. The lattice constant of the samples decreases slightly by the introduction of Co2+ The absorption edge of the ZnS:Co2+ nanoparticles is blue-shifted as compared with that of bulk ZnS, indicating the quantum confinement effect. The photoluminescence emission band exhibits a blue shift for Co-doped ZnS nanoparticles as compared to the ZnS nanoparticles. 相似文献
20.
Radiochemistry - Azathioprine, an antitumor agent, was labeled with 99mTc using stannous chloride dihydrate as a reducing agent. Factors such as the amounts of the reducing agent and substrate, pH,... 相似文献