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排序方式: 共有154条查询结果,搜索用时 140 毫秒
51.
Pourabdollah K Mokhtari B 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,84(1):22-24
Traditional methods for productivity surveillance of oil wells mainly are consisted of using test-separator units with expensive devices, protections, inspections, operations, facilities, infrastructures and repairing services. The objective of this work is to utilize a novel approach to predict the accurate productivity of oil wells using a single sample point at the line of blend oil. The present method is based upon performing multivariate regression of infrared spectra, which taken from the real samples of Iranian offshore oil wells. The experimental results revealed that the present approach is appropriate for precocious, quick and reliable surveillance of individual oil wells located in an oil field. The model has predicted the accurate productivity of real oil wells with respect to the current expensive techniques since 2010. 相似文献
52.
Novel sulfur-modified niobium(V) oxide nanoparticles (SNON) that firstly exhibited good visible light sensitization were fabricated
by a modified sol–gel technique using a very stable sol containing niobium(V) chloride, oxalic acid, isopropanol as chelating
agent and thiourea as sulfur source. The resulting S-doped Nb2O5 nanomaterials were characterized by cyclic voltammetry (CV), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy
(EDAX), scanning electron microscope (SEM), ultra-violet diffuse reflectance (UV-DRS) and thermogravimetry thermal Analysis
(TG-DTA). As against the response of unmodified niobium(V) oxide nanoparticles (UNON), the doped samples show different electrochemical
response indicating an induced charge transfer across the niobium pentoxide/solution interface, thus forming two anodic peaks
and a cathodic peak. This important observation was confirmed by UV-DRS in terms of band bending due to sulfur doping. Upon
sulfur-modification, the absorption edge extends into the visible light region. The SEM observation shows that the SNPN existed
in the mode of polycrystalline structure and the average grain size 63 nm. The EDAX analysis of undoped Nb2O5 and sulfur doped Nb2O5 shows the Nb2O5 (98%) and S (2%) content of nanopowder. These SNON nanoparticles are expected to be suitable candidates as visible light
niobium(V) oxide nanoparticles sensitization. 相似文献
53.
Bahram Mokhtari Kobra Pourabdollah 《Journal of inclusion phenomena and macrocyclic chemistry》2012,74(1-4):183-189
The novelties of this approach are introducing the self-settled dispersive liquid–liquid microextraction technique to remove the centrifuging step, conducting the dispersive liquid–liquid microextraction in complex organic systems, applicability of water as disperser phase, and inclusion microextraction of charged porphyrins by nano-baskets of calix[4]arenes, which act as the settling agents as well as the inclusion ligands. Diacid p-tert-butylcalix[4]arene in the cone conformation was synthesized and used. The related parameters including ligand concentration, volume of water disperser, salt effect, and extraction time were optimized. The linear range, detection limit (S/N?=?3) and precision (RSD, n?=?6) were determined to be 0.2–50, 0.07?μg?L?1 and 5.3%, respectively. The established method was applied to determine the target compound in five samples of live crude oil, were sampled from an Iranian offshore field. Owing to the overall differences (such as organic media, inclusion extraction, water-soluble ligands, etc.), the comparison of the proposed method with the traditional liquid–liquid microextraction was inapplicable. These results revealed that the new approach is competitive analytical tool and an alternative of the traditional methods in the crude oil and related systems. Moreover, in those systems that the inclusion separation is not requested, it is possible to use a tertiary system including a proper extraction agent/solvent and calixarene phase, as settling agent, along with the aqueous disperser in the organic systems. 相似文献
54.
Bahram Mokhtari Kobra Pourabdollah 《Journal of Thermal Analysis and Calorimetry》2012,110(3):1043-1051
Thirty-four nano-basket derivatives of di-ionizable calix[4]arene conformers in nine scaffolds bearing two pendant groups of N-(R)-sulfonyl carboxamides were synthesized and examined using isothermal titration calorimetry. The binding mechanisms of synthesized conformers toward alkali metal cations were evaluated and two main interactions were assessed including cation?C?? interaction between alkali metal and the aromatic unit of conformer as well as the strong binding ion?Cdipole interaction between nitrogen atoms in the pendant groups and alkali cation. The ITC data revealed that the bindings of cone and partial-cone conformers toward alkali metal cations exhibited one-step mechanism, while both 1,2 alternate conformer bounds the alkali metal cations in a two-step mechanism. 相似文献
55.
A new application of the Mukaiyama reagent for the simple phosphine-free conversion of alcohols into the corresponding alkyl thiocyanates is described. This transformation can be achieved either in acetonitrile or under solvent-free conditions and the products obtained in good to excellent yields. The solvent-free procedure described here is the first report on the solvent-free thiocyanation of alcohols. 相似文献
56.
Nano‐assisted inclusion separation of alkali metals from basic solutions was reported by inclusion‐facilitated emulsion liquid membrane process. The novelty of this study is application of nano‐baskets of calixarene in the selective and efficient separation of alkali metals as both the carrier and the surfactant. For this aim, four derivatives of p‐tert‐calix[4]arene bearing different sulfonamide moieties were synthesized and their inclusion‐extraction parameters were optimized. The selectivity of membrane over more than ten interfering cations was examined and the results reveled that under the optimized operating condition, the degree of inclusion‐extraction of alkali metals was as high as 98‐99%. 相似文献
57.
This article has been retracted. 相似文献
58.
Gillian A. Gehring Marzook S. AlshammariDavid S. Score James R. NealAbbas Mokhtari A. Mark Fox 《Journal of magnetism and magnetic materials》2012
A brief review of the use of magneto-optic methods to study magnetic oxides is given. A simple method to obtain the magnetic circular dichroism (MCD) of a thin film on a transparent substrate is described. The method takes full account of multiple reflections in the film and substrate. Examples of the magneto-optic spectra of Co-doped ZnO, Fe3O4, and GdMnO3 are given. The Maxwell–Garnett method is used to describe the effects of metallic cobalt inclusions in Co:ZnO samples, and the change of the MCD spectra of Fe3O4 at the Verwey temperature is discussed. Data showing different MCD signals at different energies is presented for GdMnO3. 相似文献
59.
F. Mokhtari A. Bouabdallah A. Merah H. Oualli 《Crystal Research and Technology》2012,47(12):1269-1278
The effect of axial magnetic field of different intensities on pressure in silicon Czochralski crystal growth is investigated in cylindrical and hemispherical geometries with rotating crystal and crucible and thermocapillary convection. As one important thermodynamic variable, the pressure is found to be more sensitive than temperature to magnetic field with strong dependence upon the vorticity field. The pressure at the triple point is proposed as a convenient parameter to control the homogeneity of the grown crystal. With a gradual increase of the magnetic field intensity the convection effect can be reduced without thermal fluctuations in the silicon melt. An evaluation of the magnetic interaction parameter critical value corresponding to flow, pressure and temperature homogenization leads to the important result that a relatively low axial magnetic field is required for the spherical system comparatively to the cylindrical one. 相似文献
60.
Mohsen Olyaee Mohammad Bagher Tavakoli Abbas Mokhtari 《Optical and Quantum Electronics》2018,50(11):404
We obtain the calculation of coupling coefficient of plasmonic directional coupler made up of two monolayer waveguides separated in the range of 200 nm for TM mode and we assume each waveguides acts as a perturbation to other waveguide but does not affect the waveguide mode. We simulation the transfer distance respect to normalized frequency in two directions, x and z, values transfer distance a limitation of a bandwidth is suitable for designing of integrated optical circuits and construction of couplers and switches. 相似文献