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排序方式: 共有199条查询结果,搜索用时 15 毫秒
1.
Noli Fotini Papadopoulos Pavlos Kolias Pavlos Tsiridis Eleftherios Papavasiliou Kyriakos Sayegh Fares 《Journal of Radioanalytical and Nuclear Chemistry》2019,322(2):621-628
Determination of metals and trace elements in patients with total knee or hip arthroplasty with CoCrMo alloy was performed. Blood, urine and cerebrospinal fluid (CSF) samples were analyzed and compared with samples from healthy people. Levels of Co, Cr as well as Na, Ca, Fe, Zn, Se, Rb, Sb and Br were determined by means of neutron activation analysis. The values of Cr and Co of the blood and urine measurements were elevated in patients with replacement, and according to the statistical analysis, significant differences of the elements Zn, Br, Co and Sb were found in the CSF (p?<?0.05).
相似文献2.
In this paper, the deconvolution of SIMS profiles analysed at very low primary energy (0.5 keV/O2+) is addressed. The depth resolution function (DRF) of the SIMS analysis in presence of roughness is established and a deconvolution procedure is implemented without or in presence of roughness on samples containing delta-doped layers of boron in silicon. It is shown that the deconvolution procedure can lead to a great improvement of the full width at half maximum (FWHM) of the measured peaks in the case where no roughness in detected in the crater bottom. In the case where it is present, the conditions required to use a deconvolution procedure are discussed, and the deconvolution is implemented using precise and restrictive assumptions. 相似文献
3.
Ramadan Ahmed Mekheimer Kamal Usef Sadek Hisham Ahmed Abd El‐Nabi Afaf Abd El‐Hameid Mohamed Ehab Anwer Ebraheem Michael B. Smith 《Journal of heterocyclic chemistry》2005,42(4):567-574
Ethyl 3‐amino‐4‐chlorothieno[3,2‐c]quinoline‐2‐carboxylate ( 4 ) is a versatile synthon, prepared by reacting an equimolar amount of 2,4‐dichloroquinoline‐3‐carbonitrile ( 1 ) with ethyl mercaptoacetate ( 2 ). Ethyl 5‐alkyl‐5H‐1‐thia‐3,5,6‐triazaaceanfhrylene‐2‐carboxylates 9a‐c , novel perianellated tetracyclic heteroaro‐matics, were prepared by refluxing 4 with excess of primary amines 7a‐c to yield the corresponding amino‐thieno[3,2‐c]quinolines 8a‐c . Subsequent reaction with an excess of triethyl orthoformate (TEO) furnished 9a‐c . Reaction of 4 with TEO in Ac2O at reflux, gave the simple acetylated compounds, thieno[3,2‐c]‐quinolines 12 and 13 . Refluxing 4 with benzylamine ( 7d ) gave 10 , and subsequent treatment with TEO gave the tetracyclic compound 11 . Refluxing 13 with an excess of alkylamines 7a‐d gave the fhieno[3,2‐c]quino‐lines 15 . Refluxing the aminothienoquinolines 8b with an excess of triethyl orthoacetate gave thieno[3,2‐c]quinoline 17 , while heating with Ac2O gave 18 and 19 , with small amounts of 16 . Reaction of 8a,b with ethyl chloroformate and phenylisothiocyanate generated the new 1‐thia‐3,5,6‐triazaaceanthrylenes 20a,b and 21a,b , respectively. Diazotization of 8a‐c afforded the novel tetracyclic ethyl 5‐alkyl‐5H‐1‐fhia‐3,4,5,6‐tetraazaaceanthrylene‐2‐carboxylates 22a‐c in good yields. 相似文献
4.
Mohammad M. Fares Adeeb S. El-Faqeeh 《Journal of Thermal Analysis and Calorimetry》2005,82(1):161-166
Summary Thermal degradation under N2atmosphere and thermoxidative degradation under air atmosphere of increasingly grafting efficiency values (i.e. GE%=0.0 to 35.5) for starch and starch grafted with N-tert-butylacrylamide thermosensitive copolymers (starch-g-BAM) by Ozawa and Kissinger methods using thermogravimetric analysis
(TG) and differential scanning calorimetry techniques (DSC) at 10, 30 and 50% mass losses respectively have been studied.
Influence of physical inter and intra molecular interactions on grafting and consequently on activation energy of degradation
(Ea,d) was investigated using Ozawa's method, whereas linear dependence of Ea,don GE% by scaling relations using Kissinger's method was determined. Furthermore, the thermoxidative degradation induces the possibility
of molecular rearrangement, cyclization and partial crosslinking that is deduced from the activation energy of degradation
(Ea,d) and residual mass of TG profile. Thermal stability of starch does not alter as a result of different grafting efficiency
percentages. 相似文献
5.
Coordination compounds of Fe(III), Zn(II), Ni(II), Co(II), Cu(II), Cd(II) and Mn(II) ions were synthesized from the ligand [4,4′‐((((ethane‐1,2‐diylbis(oxy))bis(2,1‐phenylene))bis(methanylylidene))bis(azanylylidene))diphenol]ethane (H2L) derived from the condensation of bisaldehyde and 4‐aminophenol. Microanalysis, magnetic susceptibility, infrared, 1H NMR and mass spectroscopies, molar conductance, X ray powder diffraction and thermal analysis were used to confirm the structure of the synthesized chelates. According to the data obtained, the composition of the 1:1 metal ion–bis‐Schiff base ligand was found to be [M(H2L)(H2O)2]Cln (M = Zn(II), Ni(II), Co(II), Cu(II), Cd(II) and Mn(II), n = 2; Fe(III), n = 3). Magnetic susceptibility measurements and reflectance spectra suggested an octahedral geometry for the complexes. Central metals ions and bis‐Schiff base coordinated together via O2 and N2 donor sites which as evident from infrared spectra. The Gaussian09 program was applied to optimize the structural formula for the investigated Schiff base ligand. The energy gaps and other important theoretical parameters were calculated applying the DFT/B3LYP method. Molecular docking using AutoDock tools was utilized to explain the experimental behaviour of the Schiff base ligand towards proteins of Bacillus subtilis (5 h67), Escherichia coli (3 t88), Proteus vulgaris (5i39) and Staphylococcus aureus (3ty7) microorganisms through theoretical calculations. The docked protein receptors were investigated and the energies of hydrogen bonding were calculated. These complexes were then subjected to in vitro antibacterial studies against several organisms, both Gram negative (P. vulgaris and E. coli) and Gram positive (S. pyogones and B. subtilis). The ligand and metal complexes exhibited good microbial activity against the Gram‐positive and Gram‐negative bacteria. 相似文献
6.
7.
Osama Abdallah Moustafa El Agamy Ehab Abdelraheem Farag Malhat 《Biomedical chromatography : BMC》2019,33(6)
An analytical method for the determination of buprofezin residues in cabbage and cauliflower was developed and validated using gas chromatography with ion trap mass spectrometry. The analyte protectant d ‐sorbitol was used at a concentration level of 0.5 mg mL?1 in acetonitrile instead of in matrix for constructing the calibration curves of the buprofezin standard. The average recoveries ranged from 91.3 to 96.8%, with an RSD of ≤2.7%. The limits of detection and quantitation of the method in cabbage and cauliflower were 1.3, 1.7 and 4.3, 6.2 μg kg?1, respectively. The residual levels and dissipation kinetics of buprofezin 25% wettabe powder in cabbage and cauliflower cultivated under open field conditions was investigated at the single (T1) and double (T2) recommended rates of application. Half‐life periods were found to be 1.73 and 2.1 days in cabbage, whereas in cauliflower, these values were 1.85 and 2.36 days at T1 and T2, respectively. Based on the dissipation study, and the maximum residue limit value of 0.05 mg kg?1, the proposed pre‐harvest interval of buprofezin in cabbage was 3–6 days and that in cauliflower was 4–10 days. The results showed that buprofezin is safe for application at both recommended application rates. 相似文献
8.
S. U. El-Kameesy S. A. El-fiki M. Ehab W. Rühm 《Isotopes in environmental and health studies》2016,52(6):567-576
Many archaeological sites in Egypt are unique worldwide, such as ancient tombs and pyramids, because they document fundamental developments in human civilization that took place several thousands of years ago. For this reason, these sites are visited by numerous visitors every year. The present work is devoted to provide a pre-operational radiological baseline needed to quantify occupational radiation exposure at the famous Saqqara region in Cairo, Egypt. A hyperpure Ge detector has been used in the γ-ray spectrometric analysis while the 222Rn concentration was measured using a portable radon monitor RTM 1688-2, SARAD. The mean specific activities of 226Ra, 232Th and 40K in the samples collected from the interior walls of the Saqqara tombs were determined and found to show average values of 16, 8.5 and 45 Bq kg?1, respectively. The concentration of radon was measured inside the tombs Serapeum, South tomb and the Zoser Pyramid (fifth level) and an associated average working level of 0.83 WL was obtained. In order to avoid the health hazards associated with the exposure to radon during the long period of work inside these tombs, proposed solutions are introduced. 相似文献
9.
10.
Ehab F. Abadir 《Journal of Thermal Analysis and Calorimetry》2013,114(3):1409-1413
The thermal degradation behaviour of ethylene-propylene-diene (EPDM) elastomer, was examined under non-isothermal conditions at different heating rates (5, 7, 10 and 12 °C/min) using thermogravimetric analysis. Kinetic parameters of degradation were evaluated using the Flynn–Wall–Ozawa isoconversional method, as well as the integral method of Coats and Redfern. A comparison between the two methods showed that the degradation of EPDM follows the Avrami–Erofeev two-dimensional nucleation model. The thermodynamic parameters were also calculated and the effect of the heating rate on each was deduced. 相似文献