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71.
Huijun Guo Wenting Sun Francis M. Haas Tanvir Farouk Frederick L. Dryer Yiguang Ju 《Proceedings of the Combustion Institute》2013,34(1):573-581
H2O2 is one of the most important species in dimethyl ether (DME) oxidation, acting not only as a marker for low temperature kinetic activity but also responsible for the “hot ignition” transition. This study reports, for the first time, direct measurements of H2O2 and CH3OCHO, among other intermediate species concentrations in helium-diluted DME oxidation in an atmospheric pressure flow reactor from 490 to 750 K, using molecular beam electron-ionization mass spectrometry (MBMS). H2O2 measurements were directly calibrated, while a number of other species were quantified by both MBMS and micro gas chromatography to achieve cross-validation of the measurements. Experimental results were compared to two different DME kinetic models with an updated rate coefficient for the H + DME reaction, under both zero-dimensional and two-dimensional physical model assumptions. The results confirm that low and intermediate temperature DME oxidation produces significant amounts of H2O2. Peroxide, as well as O2, DME, CO, and CH3OCHO profiles are reasonably well predicted, though profile predictions for H2/CO2 and CH2O are poor above and below ~625 K, respectively. The effect of the collisional efficiencies for the H + O2 + M = HO2 + M reaction on DME oxidation was investigated by replacing 20% He with 20% CO2. Observed changes in measured H2O2 concentrations agree well with model predictions. The new experimental characterizations of important intermediate species including H2O2, CH2O and CH3OCHO, and a path flux analysis of the oxidation pathways of DME support that kinetic parameters for decomposition reactions of HOCH2OCO and HCOOH directly to CO2 may be responsible for model under-prediction of CO2. The H abstraction reactions for DME and/or CH2O and the unimolecular decomposition of HOCH2O merit further scrutiny towards improving the prediction of H2 formation. 相似文献
72.
N. Farouk M. El-Tawoosy S. Ayoub A. S. El-Bayoumy 《Journal of Radioanalytical and Nuclear Chemistry》2011,290(3):685-690
Celecoxib was labelled effectively with 99mTc. The labeling yield was found to be influenced by the amount of celecoxib, the amount of stannous chloride dihydrate, the
reaction time, the temperature and the pH of the reaction mixture. The importance of stannous chloride dihydrate arises from
its function as a reducing agent for pertechnetate to form complex celecoxib. The suitable amount required to produce high
labeling yield of 99mTc-celecoxib was 500 μg SnCl2·2H2O. The pH of the reaction medium was found to play a significant role in this labeling process. The labeling reaction was
performed at a neutral medium (pH 7). The labeling reaction proceeds well at room temperature (25 ± 1 °C) and the complex
decomposes by heat. The labeled celecoxib (99mTc-celecoxib) showed a good localization in inflamed foci and a good imaging must be taken 4 h post injection. 相似文献
73.
Cartigny D Berhal F Nagano T Phansavath P Ayad T Genêt JP Ohshima T Mashima K Ratovelomanana-Vidal V 《The Journal of organic chemistry》2012,77(10):4544-4556
A general asymmetric hydrogenation of a wide range of 2-alkyl- and 2-aryl-substituted quinoxaline derivatives catalyzed by an iridium-difluorphos complex has been developed. Under mild reaction conditions, the corresponding biologically relevant 2-substituted-1,2,3,4-tetrahydroquinoxaline units were obtained in high yields and good to excellent enantioselectivities up to 95%. With a catalyst ratio of S/C = 1000 and on a gram scale, the catalytic activity of the Ir-difluorphos complex was maintained showing its potential value. Finally, we demonstrated the application of our process in the synthesis of compound (S)-9, which is an inhibitor of cholesteryl ester transfer protein (CETP). 相似文献
74.
H. Aglan S. A. Kandil H. A. Hanafi M. A. Mousa Z. A. Saleh 《Journal of Radioanalytical and Nuclear Chemistry》2009,280(3):533-538
The radiochemical separation of no-carrier-added cerium from proton irradiated lanthanum was studied by solvent extraction
using DEE, TBP and TPPO, the latter reagent being employed for the first time for separation of radiocerium from bulk of lanthanum.
Distribution coefficients of cerium and lanthanum were investigated as a function of equilibrium time and concentration of
HNO3. A mixture of 0.05M K2Cr2O7 and 0.1M H2SO4 was used as an oxidizing agent to improve the separation efficiency of cerium. A comparative study of the three extractants
released that DEE is the best for separation of cerium from bulk of lanthanum oxide. The target was prepared by pressing.
The production of 139Ce of high radionuclidic purity and chemical purity via irradiation of lanthanum oxide target at MGC-20 cyclotron with protons
of energy 14.5 MeV is described. The experimental yield was found to be 153 kBq/μA·h. 相似文献
75.
Ahmed Farouk J. Batle M. Elhoseny Mosayeb Naseri Muzaffar Lone Alex Fedorov Majid Alkhambashi Syed Hassan Ahmed M. Abdel-Aty 《Frontiers of Physics》2018,13(2):130306
Quantum communication provides an enormous advantage over its classical counterpart: security of communications based on the very principles of quantum mechanics. Researchers have proposed several approaches for user identity authentication via entanglement. Unfortunately, these protocols fail because an attacker can capture some of the particles in a transmitted sequence and send what is left to the receiver through a quantum channel. Subsequently, the attacker can restore some of the confidential messages, giving rise to the possibility of information leakage. Here we present a new robust General Nuser authentication protocol based on N-particle Greenberger–Horne–Zeilinger (GHZ) states, which makes eavesdropping detection more effective and secure, as compared to some current authentication protocols. The security analysis of our protocol for various kinds of attacks verifies that it is unconditionally secure, and that an attacker will not obtain any information about the transmitted key. Moreover, as the number of transferred key bits N becomes larger, while the number of users for transmitting the information is increased, the probability of effectively obtaining the transmitted authentication keys is reduced to zero. 相似文献
76.
Arafa Musa Ehab M. Mostafa Syed Nasir Abbas Bukhari Nasser Hadal Alotaibi Ahmed H. El-Ghorab Amr Farouk AbdElAziz A. Nayl Mohammed M. Ghoneim Mohamed A. Abdelgawad 《Molecules (Basel, Switzerland)》2022,27(4)
For most researchers, discovering new anticancer drugs to avoid the adverse effects of current ones, to improve therapeutic benefits and to reduce resistance is essential. Because the COX-2 enzyme plays an important role in various types of cancer leading to malignancy enhancement, inhibition of apoptosis, and tumor-cell metastasis, an indispensable objective is to design new scaffolds or drugs that possess combined action or dual effect, such as kinase and COX-2 inhibition. The start compounds A1 to A6 were prepared through the diazo coupling of 3-aminoacetophenone with a corresponding phenol and then condensed with two new chalcone series, C7–18. The newly synthesized compounds were assessed against both COX-2 and epidermal growth factor receptor (EGFR) for their inhibitory effect. All novel compounds were screened for cytotoxicity against five cancer cell lines. Compounds C9 and G10 exhibited potent EGFR inhibition with IC50 values of 0.8 and 1.1 µM, respectively. Additionally, they also displayed great COX-2 inhibition with IC50 values of 1.27 and 1.88 µM, respectively. Furthermore, the target compounds were assessed for their cytotoxicity against pancreatic ductal cancer (Panc-1), lung cancer (H-460), human colon cancer (HT-29), human malignant melanoma (A375) and pancreatic cancer (PaCa-2) cell lines. Interestingly, compounds C10 and G12 exhibited the strongest cytotoxic effect against PaCa-2 with average IC50 values of 0.9 and 0.8 µM, respectively. To understand the possible binding modes of the compounds under investigation with the receptor cites of EGFR and COX-2, a virtual docking study was conducted. 相似文献
77.
78.
79.
M. N. H. Comsan M. A. Farouk A. A. El-Kamhawy M. S. M. El-Tahawy A. N. Lvov 《Zeitschrift für Physik A Hadrons and Nuclei》1968,212(1):71-82
Proton gamma angular correlations through the 6.76 and 8.92 MeV excited states of B11 are measured at deuteron bombarding energies from 1.6 to 2.4 MeV. The correlations are measured at laboratory proton scattering angles 35? in both reaction and azimuthal planes. The correlation coefficientA 2 0 and the distortion parameterλ are calculated. A systematic shift of the symmetry axis from the recoil direction is observed. This shift tends to zero asE d→Q. For the 8.92 MeV excited state of B11(Q=0.32 MeV) the distortion parameterλ is close to the plane wave limit. The possible values of incoming channel spins as well as gamma-ray multipole mixing ratio for the 6.76 and 8.92 MeV states are obtained. 相似文献
80.
Dr. M. N. H. Comsan M. A. Farouk A. A. El-Kamhawy M. S. M. El-Tahawy A. N. Lvov 《Zeitschrift für Physik A Hadrons and Nuclei》1968,212(2):122-129
Thep-γ angular correlations in B11(d, p)B12 reaction have been measured in both reaction and azimuthal planes for proton angles 35° at ED=1.60 and 2.40 MeV. The correlation coefficient A 2 0 and the distortion parameterλ were calculated. The obtained values of the shift of the symmetry axis from the recoil direction, Φ0 and the parameterλ are far from there plane wave limits. The anisotropy of the angular correlation gives two possible values, 1+ and 2+, for the spin of the first excited state of B12. 相似文献