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481.
Mohamed Hilmy Elnagdi Mohamed Ali Elsayed Khalifa Mohamed Kamal Ahmed Ibraheim Mohamed Riffat Hamza Elmoghayar 《Journal of heterocyclic chemistry》1981,18(5):877-879
The reaction of mercaptoacetic acid with nitriles was investigated. Whereas 4-hydroxythiazole derivative could be obtained from the reaction of benzoylacetonitrile and of ethyl cyanoacetate with mercaptoacetic acid, a bithiazole derivative was obtained on treatment of benzonitrile with the same reagent. The behaviour of the synthesised thiazole derivatives towards aromatic aldehydes and hydrazines is reported. 相似文献
482.
A. Z. Nowakowski R. B. Dennis T. Scragg F. H. Hamza S. D. Smith 《Optics & Laser Technology》1976,8(3):133-136
Double beam optical techniques which allow direct spectroscopic measurements using both pulsed and cw tunable spin-flip Raman lasers have been developed. The systems provide a high resolution spectrometer (spectral linewidths 0.03 cm-1 pulsed and 0.003 cm-1 cw) in the range 5.3–6μm. Line frequency measurements are accurate to 0.01 cm-1 and intensity measurements to a few percent. Results of molecular spectroscopy provide a comparison of the relative performance of each system. 相似文献
483.
A.A. Hamza A.E. Belal T.Z.N. Sokkar H.M. EL-Dessouky M.A. Agour 《Optics and Lasers in Engineering》2007,45(1):145-152
Opto-thermal device attached to automate Fizeau interferometer is used to investigate the influence of temperature on opto-thermal properties of multimode graded-index (GRIN) optical fibre in the range from 27 to 54 °C. The effect of temperature on the refractive index profile of fibre is studied. The optical parameters and the opto-thermal coefficient of this fibre are determined. Also the variation of oscillation and dispersion energies, zero dispersion wavelengths, coupling efficiency, normalised frequency, number of propagation modes with the temperature and the material dispersion with the wavelength at different temperatures are calculated. Microinterferograms are given for illustration. 相似文献
484.
Motohiro Yasui Ayano Yamada Chihiro Tsukano Andrea Hamza Imre Ppai Yoshiji Takemoto 《Angewandte Chemie (International ed. in English)》2020,59(32):13479-13483
Although acetalization is a fundamental transformation in organic synthesis, intermolecular asymmetric acetalization remains an unsolved problem. In this study, a thiourea‐ammonium hybrid catalyst was shown to promote the O‐alkylation of enols with a racemic γ‐chlorobutenolide through dynamic kinetic resolution to give chiral acetals with good enantioselectivity. The catalyst simultaneously activates both the nucleophile and electrophile in a multifunctional manner. This method was applied to the asymmetric synthesis of several strigolactones. DFT calculations suggest that hydrogen‐bonding interactions between the chlorine atom of the γ‐chlorobutenolide and the tosylamide hydrogen atom of the catalyst, as well as other types of noncovalent catalyst–substrate interactions, are crucial for achieving high stereoselectivity. 相似文献
485.
Nur Ezwan Anis Muhd Subuhi Salwani Md Saad Nur Nadhirah Mohamad Zain Vuanghao Lim Mazidatulakmam Miskam Sazlinda Kamaruzaman Muggundha Raoov Noorfatimah Yahaya 《Journal of separation science》2020,43(16):3294-3303
In this work, a simple, fast, sensitive, and environmentally friendly method was developed for preconcentration and quantitative measurement of bisphenol A in water samples using gas chromatography with mass spectrometry. The preconcentration approach, namely biosorption‐based dispersive liquid‐liquid microextraction with extractant removal by magnetic nanoparticles was performed based on the formation of microdroplet of rhamnolipid biosurfactant throughout the aqueous samples, which accelerates the mass transfer process between the extraction solvent and sample solution. The process is then followed by the application of magnetic nanoparticles for easy retrieval of the analyte‐containing extraction solvent. Several important variables were optimized comprehensively including type of disperser solvent and desorption solvent, rhamnolipid concentration, volume of disperser solvent, amount of magnetic nanoparticles, extraction time, desorption time, ionic strength, and sample pH. Under the optimized microextraction and gas chromatography with mass spectrometry conditions, the method demonstrated good linearity over the range of 0.5–500 µg/L with a coefficient of determination of R2 = 0.9904, low limit of detection (0.15 µg/L) and limit of quantification (0.50 µg/L) of bisphenol A, good analyte recoveries (84–120%) and acceptable relative standard deviation (1.8–14.9%, n = 6). The proposed method was successfully applied to three environmental water samples, and bisphenol A was detected in all samples. 相似文献
486.
Eman Kh. Hamza Nehal A. Hamdy Eman S. Zarie Issa M.I. Fakhr Ahmed H.M. Elwahy Hanem M. Awad 《Journal of heterocyclic chemistry》2020,57(1):182-196
New hybrids of tetralin-pyrazolo[3,4-b]pyridine were synthesized in good yields. The structures of newly synthesized compounds were confirmed by IR, NMR, MS, and elemental analyses. Some of the new compounds were in vitro evaluated as antiproliferative candidates against two human cancer cell lines (HCT116 and MCF-7). Most of the examined derivatives showed promising anticancer activity. 相似文献
487.
Dr. Motohiro Yasui Ayano Yamada Dr. Chihiro Tsukano Dr. Andrea Hamza Prof. Imre Pápai Prof. Yoshiji Takemoto 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(32):13581-13585
Although acetalization is a fundamental transformation in organic synthesis, intermolecular asymmetric acetalization remains an unsolved problem. In this study, a thiourea-ammonium hybrid catalyst was shown to promote the O-alkylation of enols with a racemic γ-chlorobutenolide through dynamic kinetic resolution to give chiral acetals with good enantioselectivity. The catalyst simultaneously activates both the nucleophile and electrophile in a multifunctional manner. This method was applied to the asymmetric synthesis of several strigolactones. DFT calculations suggest that hydrogen-bonding interactions between the chlorine atom of the γ-chlorobutenolide and the tosylamide hydrogen atom of the catalyst, as well as other types of noncovalent catalyst–substrate interactions, are crucial for achieving high stereoselectivity. 相似文献
488.
489.
Hafeez-Ullah Atif M. Firdous S. Mehmood M. S. Hamza M. Y. Imran M. Hussain G. Ikram M. 《Optics and Spectroscopy》2011,110(2):313-319
The purpose of the present study is to determine the optical properties of normal and thermally coagulated chicken liver at
720, 740, 770, 810, 825 and 840 nm wavelengths of laser irradiation. So, we were able to evaluate these optical properties
(absorption and scattering coefficients) with ex-vivo study using Kubelka Munk Model (KMM) from the radial dependence of the diffuse reflectance with femtosecond pulsed laser
in near IR region. These coefficients were significantly increased with coagulation. The penetration depths of the diffused
light have been reported to a maximum value of 8.12 ± 0.36 mm in normal liver and 2.49 ± 0.17 mm in coagulated liver at 840
nm showing increasing behavior towards IR region. The Monte Carlo simulation was used to check the theoretical validation
of measured optical properties of the tissue that showed a good match with our experimental results. We believe that these
differences in optical properties will be helpful for the understanding arid optimal use of laser applications in medicine
and differential diagnosis of tissues by using different optical methods. Especially for the investigation of biological tissue
for photodynamic therapy (PDT), the knowledge of the specific optical properties and their thermo-induced changes is important. 相似文献
490.
The production of charged pion pairs via multiphoton absorption from an intense X-ray laser wave colliding with an ultrarelativistic proton beam is studied. Our calculations include the contributions from both the electromagnetic and hadronic interactions where the latter are described approximately by a phenomenological meson-exchange potential. Order-of-magnitude estimates for π+π− production on the proton by two- and three-photon absorption from the high-frequency laser field are obtained and compared with the corresponding rates for μ+μ− pair creation. 相似文献