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1.
The increasing use of Ultraviolet (UV) light in medicine, industrial environments, for cosmetic use, and even in consumer products necessitates that greater attention be paid to the potential hazards of this type of electromagnetic radiation. To avoid any adverse effects of exposure to this type of radiation, four suitable protection filters were produced to block three UV bands (UVA, UVB, and UVC). The design structure of the required dielectric multilayer filters was done by optical thin film technology using the absorbing property of UV radiation for the substrates and dielectric materials. The computer analyses of the multilayer filter formulas were prepared using Macleod Software for the production processes. The deposition technique was achieved on optical substrates (Glass BK-7 and Infrasil 301) by dielectric material combinations including Titanium dioxide (Ti2O3), Hafnium dioxide (HfO2), and Lima (mixture of oxides SiO2/Al2O3); deposition being achieved using an electron beam gun. The output results of the theoretical and experimental transmittance values for spectral band from 200 nm to 800 nm were discussed in four processes. To analyze the suitability for use in ‘real world’ applications, the test pieces were subjected to the durability tests (adhesion, abrasion resistance, and humidity) according to Military Standard MIL-C-675C and MIL-C-48497A. 相似文献
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3.
Abdel-Aziz Y. El-Sayed 《Fresenius' Journal of Analytical Chemistry》1994,349(12):830-832
A new catalytic method was described for the determination of ruthenium(III) based on its catalytic effect on the oxidation of hematoxylin by hydrogen peroxide in weakly acidic medium. The reaction was followed spectrophotometrically by measuring the absorbance of hematoxylin at 440 nm. Under the optimum conditions, ruthenium(III) can be determined in the range 5–120 ng/ml with a relative standard deviation of 1.1%. The mean value of reaction rate constant was 0.012±0.04 min–1 and the activation energy was 10.45 kJ/mol. The method was tested for the determination of ruthenium(III) in some synthetic mixtures. 相似文献
4.
Salama Tarek A. El-Ahl Abdel-Aziz S. Khalil Abdel-Galil M. Girges Margret M. Lackner Bernd Steindl Christian Elmorsy Saad S. 《Monatshefte für Chemie / Chemical Monthly》2003,134(9):1241-1252
Summary. Several new 1-aryl-, aralkyl-, and heteroaryl-5-(4-phenylbuta-1,3-dienyl)tetrazole derivatives and annulated tetrazole derivatives were efficiently and regiospecifically prepared in nearly quantitative yield via a facile one step reaction of dienones with a combination of tetrachlorosilane and sodium azide in acetonitrile under mild conditions. A complete structure assignment of three representative examples of the tetrazoles was achieved by advanced 2D NMR measurements including COSY, TOCSY, HSQC, HMBC, NOESY, and ROESY experiments.Received March 17, 2003; accepted March 18, 2003
Published online July 28, 2003 相似文献
5.
Tarek A. Salama Abdel-Aziz S. El-Ahl Abdel-Galil M. Khalil Margret M. Girges Bernd Lackner Christian Steindl Saad S. Elmorsy 《Monatshefte für Chemie / Chemical Monthly》2003,20(5):1241-1252
Several new 1-aryl-, aralkyl-, and heteroaryl-5-(4-phenylbuta-1,3-dienyl)tetrazole derivatives and annulated tetrazole derivatives were efficiently and regiospecifically prepared in nearly quantitative yield via a facile one step reaction of dienones with a combination of tetrachlorosilane and sodium azide in acetonitrile under mild conditions. A complete structure assignment of three representative examples of the tetrazoles was achieved by advanced 2D NMR measurements including COSY, TOCSY, HSQC, HMBC, NOESY, and ROESY experiments. 相似文献
6.
Alaa A.-M. Abdel-Aziz Serry A.A. El Bialy Takehisa Kunieda 《Tetrahedron letters》2004,45(43):8073-8077
An enantioselective synthesis of sterically congested 1,2-di-tert-butyl and 1,2-di-(1-adamantyl)ethylenediamines has been developed. Thus, diastereomerically pure trans-1-apocamphanecarbonyl-4,5-dimethoxy-2-imidazolidinones 6 and 7 were successfully prepared by optical resolution of (±)-trans-4,5-dimethoxy-2-imidazolidinone using apocamphanecarbonyl chloride (MAC-Cl) followed by stereospecific and stepwise substitution of the dimethoxyl groups using tert-butyl or 1-adamantyl cuprates to provide (4S,5S)-4,5-di-tert-butyl and (4R,5R)-4,5-di-(1-adamantyl)-2-imidazolidinones 12 and 15, respectively. Furthermore, N-acetyl 4,5-di-tert-butyl and 4,5-di-(1-adamantyl)-2-imidazolidinones 16a,b were enantioselectively deacetylated using a catalytic oxazaborolidine system to provide enantiopure 1-p-tolylsulfonyl-4,5-di-tert-butyl-2-imidazolidinones 12 and 19 and 1-p-tolylsulfonyl-4,5-di-(1-adamantyl)-2-imidazolidinones 18 and 20, respectively. Finally, N-p-tolylsulfonyl-2-imidazolidinones 12 and 15 were treated with 30 equiv of Ba(OH)2·8H2O to achieve ring cleavage and to provide (1S,2S)-1,2-di-tert-butylethylenediamine 3 and (1R,2R)-1,2-di-(1-adamantyl)ethylenediamine 4. 相似文献
7.
A method is presented for the simultaneous determination of chromium, iron, cobalt and zinc in samples of uranium concentrates, oxides and metallic uranium by neutron-activation analysis. The method involves adequate decontamination of gross fission product activities by adsorption on silica gel, removal of uranium by solvent extraction, separation of most carrier-free rare-earth activities by coprecipitation with aluminium chloride, and, finally, fractional separation of the elements concerned by ion-exchange chromatography. The method can assay ppm of such elements in limited quantities of samples by scintillation gamma-ray spectrometric analysis with a reproducibility of 10-15%. 相似文献
8.
Hatem A. Abdel-Aziz Mashooq A. Bhat Mohamed Ghazzali 《Phosphorus, sulfur, and silicon and the related elements》2013,188(9):1328-1336
AbstractThe reaction of thiosemicarbazides 1a–h with hydrazonoyl chlorides 2a–g at ambient temperature, in the presence of triethylamine yielded, in each case, two products. The structure of these compounds was confirmed as 1,3,4-oxadiazoles 14a–h and hydrazonothioates 15a–g. The structure of 15b was confirmed through single crystal X-ray diffraction. A mechanism was proposed for this cyclodesulfurization reaction. 相似文献
9.
Abdel-Aziz S. El-Ahl Fatty A. Amer Akram H. Elbeheery 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):2226-2235
Abstract Unprecedented high-yield simple and mild conversion of primary aliphatic and aromatic thioamides into 5-substituted tetrazoles on treatment with a combination of tetrachlorosilane and sodium azide in refluxing acetonitrile has been achieved. Secondary acyclic, cyclic, and heterocyclic thioamides could also be transformed in high yields into 1-substituted, 1,5-disubstituted, or annulated tetrazoles under the same reaction condition. GRAPHICAL ABSTRACT 相似文献
10.