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41.
A. Varinlioğlu S. Topcuoğlu A. Köse A. I. Kopya O. Uzun A. Azar H. Karal 《Journal of Radioanalytical and Nuclear Chemistry》1994,187(6):435-440
Moss samples collected from the eastern Black Sea about 6.5 years after the Chernobyl accident have been analyzed for radiocesium activity.134Cs activity was also detected in all the samples beside137Cs radionuclide. The levels of total cesium activity in the mosses proved that the coastal zone in the eastern Black Sea region was highly contaminated. 相似文献
42.
John Ellis Azar Mustafayev Keith A. Olive 《The European Physical Journal C - Particles and Fields》2010,69(1-2):219-233
In the context of phenomenological models in which the soft supersymmetry-breaking parameters of the MSSM become universal at some unification scale, M in, above the GUT scale, M GUT, it is possible that all the scalar mass parameters m 0, the trilinear couplings A 0 and the bilinear Higgs coupling B 0 vanish simultaneously, as in no-scale supergravity. Using these no-scale inputs in a renormalisation-group analysis of the minimal supersymmetric SU(5) GUT model, we pay careful attention to the matching of parameters at the GUT scale. We delineate the region of M in, m 1/2 and tan?β where the resurrection of no-scale supergravity is possible, taking due account of the relevant phenomenological constraints such as electroweak symmetry breaking, m h ,b→s γ, the neutralino cold dark matter density Ω χ h 2 and g μ ?2. No-scale supergravity survives in an L-shaped strip of parameter space, with one side having m 1/2?200 GeV, the second (orthogonal) side having M in?5×1016 GeV. Depending on the relative signs and magnitudes of the GUT superpotential couplings, these may be connected to form a triangle whose third side is a hypotenuse at larger M in, m 1/2 and tan?β, whose presence and location depend on the GUT superpotential parameters. We compare the prospects for detecting sparticles at the LHC in no-scale supergravity with those in the CMSSM and the NUHM. 相似文献
43.
Iman Manavi-Tehrani Mohammad Rabiee Maryam Parviz Mohammad Reza Tahriri Zahra Fahimi 《Macromolecular Symposia》2010,296(1):457-465
In the present research hydrogel films based on polyvinyl alcohol (PVA) and polyacrylic acid (PAA) blend, with various crosslink densities, have been prepared through different thermal treatment. The results of FTIR and DSC confirmed quality and quantity of conclusion on miscibility of PVA/PAA blends, respectively. Besides, biocompatibility of the samples has been proved in cytotoxicity tests using L929 cells, according to ISO10993–5. Water uptake of the hydrogel blends is measured. pH sensitivity properties of blends are studied with and without boiling in NaOH solutions where the effect of swelling in water before boiling has also been investigated. Preswellings in water and NaOH concentration have been found to be mainly effective on pH sensitivity of PVA/PAA blends. Biocompatibility and pH sensitivity behavior make these hydrogels appropriate candidates to orally deliver drugs such as insulin and peptides that can be released in basic pH of intestine. The stability of these films in acidic solutions and its expansion and also the consequent release of drugs in basic solutions have been studied by using Teofilin as a model drug by UV-spectrophotometeric measurements. 相似文献
44.
Parviz Khajeh-Khalili 《Applicable analysis》2013,92(1-3):229-234
In this article we consider asymptotic behavior of some bifurcation curves of the two-point boundary value problem -u′ (x) =λf(u(x)) for 0 < x < 1; u(0) = u(1) = 0. Infact we prove that λ grows linearly with respective to p(p = u(1/2)) for p large 相似文献
45.
Ming-Yuan Wei Leila Famouri Lloyd Carroll Yongkuk Lee Parviz Famouri 《Ultrasonics sonochemistry》2013,20(1):610-617
Gold nanoparticles (NPs) are rapidly and efficiently formed under ambient conditions with a novel and highly-efficient sonochemical promoter. Despite of the presence of free oxygen, 3-glycidoxypropyltrimethoxysilane (GPTMS) showed remarkable efficiency in promoting the reduction rate of Au (III) than that of conventional promoters (primary alcohols). This is likely attributed to the formation of a variety of radical scavengers, which are alcoholic products from sonochemical hydrolysis of the epoxide group and methoxysilane moieties of GPTMS under weakly acidic conditions. Interestingly, the promotion is quenched by amine- or thiol-functionalized alkoxysilane, thereby producing marginal amounts of gold NPs. Furthermore, products of hydrolyzed GPTMS were confirmed to attach on the surface of gold NPs by attenuated total reflectance-Fourier transform infrared spectroscopy. However, according to transmission electron microscopy images, gold NPs that were produced in the presence of GPTMS tend to fuse with each other as condensation of silanols occurs, forming worm- or nugget-like gold nanostructures. The use of long chain surfactants (i.e. polyethylene glycol terminated with hydroxyl or carboxyl) inhibited the fusion, leading to mono-dispersed gold NPs. Additionally, the fact that this approach requires neither an ultrasound source with high frequency nor anaerobic conditions provides a huge advantage. These findings could potentially open an avenue for rapid and large-scale green-synthesis of gold NPs in future work. 相似文献
46.
ABSTRACTIn this paper, lanthanum was used as a chemical modifier for the direct determination of erbium by high-resolution continuum source electrothermal atomic absorption spectrometry. A two-step experimental design was used for optimization, first a full factorial design was conducted for identification of significant factors, and then a central composite design was carried out for final optimization of the significant factors. The optimum parameters were obtained as follows: atomization temperature of 2500°C, pyrolysis temperature of 1600°C, and pyrolysis time of 10?s in the presence of lanthanum as a chemical modifier. Under optimum conditions, the characteristic mass, limit of detection, and limit of quantification were 29?pg, 0.71, and 2.4?µg?L?1, respectively. The precision of the method, estimated as the relative standard deviation for 10 replicate measurements of 50?µg?L?1 of erbium, was 1.8%. The optimized method was applied to determine erbium content in sediments and rock samples. The determined values of erbium in sediment certified reference materials were in satisfactory agreement with the certified values according to the t-test for a 95% confidence level. 相似文献
47.
Mackenzie Kelley Nastaran Abdol Parviz Soroushian Kristina Keating Anagi M. Balachandra Tyler Meldrum 《Journal of polymer science. Part A, Polymer chemistry》2020,58(4):616-623
Adhesively bonded joints using epoxy are widely used in aircraft and aerospace structures. Quality control and defect detection during epoxy curing in such applications is critical. We used single-sided nuclear magnetic resonance (NMR) to nondestructively probe and spatially resolve the change in the characteristic NMR relaxation time (T2) of epoxies during curing on a substrate. Time-dependent T2 values were fit to a Weibull function to model temporal changes in the NMR measurables. Our results demonstrate that the reduction in molecular mobility of various epoxy/curing agent mixtures occurs more rapidly at the interface than in the bulk. Further use of single-sided NMR to acquire spatially resolved T2 data will provide a route for elucidatory epoxy curing studies. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 616–623 相似文献
48.
Seyyed Javad Sabounchei Khadijeh Badpa Mehdi Bayat Roya Karamian Fatemeh Ghasemlou Robert W. Gable Parviz Gohari Derakhshandeh Kristof Van Hecke 《应用有机金属化学》2019,33(3)
The reaction of α‐keto‐stabilized diphosphine ylides [Ph2P(CH2)nPPh2═C(H)C(O)C6H4‐p‐CN] (n = 1 (Y1); n = 2 (Y2)) with dibromo(1,5‐cyclooctadiene) palladium(II)/platinum(II) complexes, [Pd/PtBr2(cod)], in equimolar ratio gave the new cyclometalated Pd(II) and Pt(II) complexes [Br2Pd(κ2‐Y1)] ( 1 ), [Br2Pt(κ2‐Y1)] ( 2 ), [Br2Pd(κ2‐Y2)] ( 3 ) and [Br2Pt(κ2‐Y2)] ( 4 ). These compounds were screened in a search for novel antibacterial agents and characterized successfully using Fourier transfer infrared and NMR (1H, 13C and 31P) spectroscopic methods. Also, the structures of complexes 1 and 2 were characterized using X‐ray crystallography. The results showed that the P,C‐chelated complexes 1 and 2 have structures consisting of five‐membered rings, while 3 and 4 have six‐membered rings, formed by coordination of the ligand through the phosphine group and the ylidic carbon atom to the metal centre. Also, a theoretical study of the structures of complexes 1 – 4 was conducted at the BP86/def2‐SVP level of theory. The nature of metal–ligand bonds in the complexes was investigated using energy decomposition analyses (EDA) and extended transition state combined with natural orbitals for chemical valence analyses. The results of EDA confirmed that the main portions of ΔEint, about 57–58%, in the complexes are allocated to ΔEelstat. 相似文献
49.
50.
Mona Ghoorchibeigi Kambiz Larijani Parviz A. Azar Karim Zare Iraj Mehregan 《Journal of heterocyclic chemistry》2020,57(10):3612-3621
The preparation of pyrazolo pyrimidinone derivatives was performed by using five component reactions of phthalaldehyde, cyanomethylamine, electron deficient acetylenic compounds, isocyanate, hydrazine, and catalytic amounts of ZnO/Fe3O4-magnetic nanoparticles as a high performance catalyst under ultrasonic conditions at ambient temperature in aquause media at room temperature. It should be mentioned that this catalyst was prepared using Spinacia oleracea water extract. In addition, for investigation of antioxidant ability, radical trapping by DPPH and reducing power of ferric ion experiments was performed. As a result, synthesized compounds show excellent radical trapping by DPPH and good reducing ability of ferric ion. The current procedure has the benefits for instance excellent yield of reaction, green media, and easy separation of product and catalyst. 相似文献