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21.
Saeed Golmohammadi Hashem Imani Amin Khalafi Ghader Karimian Ali Rostami 《Fiber and Integrated Optics》2013,32(3):178-191
Abstract Resolution enhancement of a high-speed fiber-optic spectrometer is investigated in this article. The operation of these types spectrometers is based on conversion of the spectral-domain signal into the time domain by a dispersive element. A photonic crystal fiber is used as a dispersive fiber in this spectrometer. Resolution enhancement of considered spectrometer with photonic crystal fibers is studied. The fiber loss and length minimization in this spectrometer are obtained. Simulation results show that an increase in resolution will cause a decrease in the speed of the spectrometer. Trade offs between resolution and speed are studied. 相似文献
22.
Morteza Soltani‐Shahrivar Nashmil Karimian Hanieh Fakhri Ali Hajian Abbas Afkhami Hasan Bagheri 《Electroanalysis》2019,31(12):2455-2465
A novel, stable and sensitive non‐enzymatic sensor was developed with metal‐organic frameworks (MOFs) that have attracted great attention in electrochemical sensors applications in recent years. The pore structures of MIL (Fe)‐101 and MIL (Fe)‐53 are the families of MOFs that were constructed via a simple solvothermal procedure. The 35MIL‐101(Fe)‐reduced graphene oxide nanocomposite has been used for modification of glassy carbon electrode for the determination of carbofuran (CBF) and carbaryl (CBR). The porosity of the composites increased the voltammetric responses significantly for CBF and CBR in a mixed solution that makes the simultaneous determination of both carbamate pesticides possible. Characterization of MIL (Fe)‐101 and MIL (Fe)‐53 were performed with FT‐IR, XRD, BET and SEM. Finally, the introduced sensor under the optimal conditions showed low detection limits of 1.2 and 0.5 nM within the linear ranges of 5.0–200.0 nM and 1.0–300.0 nM for CBF and CBR, respectively. The non‐enzymatic sensor was successfully used to monitoring of carbamates residue in vegetable and fruit samples. 相似文献
23.
The computational cost of numerical methods in microscopic-scales such as molecular dynamics (MD) is a deterrent factor that limits simulations with a large number of particles. Hence, it is desirable to decrease the computational cost and run time of simulations, especially for problems with a symmetrical domain. However, in microscopic-scales, implementation of symmetric boundary conditions is not straight-forward. Previously, the present authors have successfully used a symmetry boundary condition to solve molecular flows in constant-area channels. The results obtained with this approach agree well with the benchmark cases. Therefore, it has provided us with a sound ground to further explore feasibility of applying symmetric solutions of micro-fluid flows in other geometries such as variable-area ducts. Molecular flows are solved for the whole domain with and without the symmetric boundary condition. Good agreement has been reached between the results of the symmetric solution and the whole domain solution. To investigate robustness of the proposed method, simulations are conducted for different values of affecting parameters including an external force, a flow density, and a domain length. The results indicate that the symmetric solution is also applicable to variable-area ducts such as micro-nozzles. 相似文献
24.
Khashayar Karimian Farajolah Mohanazadeh Shaheen Rezai 《Journal of heterocyclic chemistry》1983,20(4):1119-1121
Covalent immobilization of the thiazole nucleus on a chloromethylated polystyrene copolymer results in the formation of a catalytically active thiazolium salt, capable of repeated acyloin and benzoin condensations. The nature of the solvent and the substituents on the thiazolium nucleus has been found to have marked effects of the rate of catalysis. 相似文献
25.
S. Mahdizadeh G. H. Rounaghi M. Mohajeri F. Karimian 《Russian Journal of Inorganic Chemistry》2016,61(6):791-798
The complexation reactions between La3+, Y3+ and Ce3+ cations with the macrocyclic ligand, kryptofix 21, were studied in methanol-acetonitrile (MeOH-AN) and methanol-methylacetate (MeOHMeOAc) binary mixed solvent solutions at different temperatures using the conductometric method. The conductance data show that in most solvent systems, the kryptofix 21 forms a 1: 1 [M: L] complex with La3+, Y3+ and Ce3+ metal cations, but in the case of Y3+ cation in pure methylacetate, in addition of formation of a 1: 1 [ML] complex, 1: 2 [ML2] and 1: 3 [ML3] complexes are formed in solution. In the case of Ce3+cation, a 1: 1 [ML] and also a 1: 2 [ML2] complexes are formed in this solvent system at all studied temperatures. The electrical conductance data in acetonitrile, show that a 1: 1 [ML] and also a 1: 2 [ML2] complexes are formed between the ligand and La3+ and Ce3+ metal cations at different temperatures. The stability constants of the 1: 1 [ML] complexes were determined using the conductometric data and a computer program, GENPLOT. A non-monotonic relationship was observed between logK f of the 1: 1 complexes with the composition of the binary solvent solutions which was discussed in term of solvent-solvent interactions and also preferential solvation of the metal cations and the ligand in solutions. The selectivity order of the ligand for the metal cations in MeOH–AN and MeOH–MeOAc binary solvent solutions, at 25°C was found to be: Y3+ > La3+ > Ce3+ and La3+ > Y3+ > Ce3+, respectively. The values of the standard thermodynamic quantities (ΔH c ° and ΔS c ° ) for formation of the 1: 1 complexes were obtained from temperature dependence of the stability constans of the complexes and the results show that the thermodynamics of the complexation reactions between kryptofix 21 and La3+, Y3+ and Ce3+ cations, is affected by the nature and composition of the mixed solvents systems. 相似文献
26.
A useful and green synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones derivatives were achieved by one-pot cyclocondensation between substituted aryl aldehydes, diketone/ketoester, and urea/thiourea using magnetic CoNiFe2O4@Silica-SO3H nanoparticles under solvent-free condition. The choice of this approach showed essential advantages such as short reaction time, simple work-up procedure, high activity of the catalyst, high yield of the reaction products, the magnetic properties of the catalyst, and environmentally amiable conditions. In addition, the catalyst recovered and reused four times without notable loss of its activity. The magnetic CoNiFe2O4@Silica-SO3H nanoparticles were described by Fourier-transform infrared spectroscopy (FT-IR), field emission scanning electron microscope, energy dispersive X-ray spectroscopy, X-ray diffraction spectroscopy, and vibrating sample magnetometer. The products were obtained with excellent yields (88–98%). The formation of the products was confirmed and identified with their physical properties (melting points), the FT-IR, 1H NMR, 13C NMR, mass spectrometry, and the elemental analysis. 相似文献
27.
This review deals with recent advances in the field of electrochemical sensing and biosensing with nanoelectrode ensembles (NEEs) and nanoelectrode arrays (NEAs), focusing mainly on articles published since 2015. At first, a brief introduction on the properties and possible advantages which characterize electroanalytical signals at the NEE/NEA is presented, followed by an overview on the most recent theoretical advances concerning the modeling of relevant electrochemical signals. Novel nanofabrication methods and nanoelectrode materials are discussed together with original (bio)funtionalization procedures, suitable to obtain more sensitive and reliable sensors. Advanced applications of NEE/NEA-based sensors in the biological and biomedical field are presented, including their integration with living cells and application for neurochemical studies. Advances, present limits, and prospects for research in the area are finally discussed. As far as future research trends are concerned, on the one hand, there is a need for development of theoretical models which take into account specific effects that can rule electrochemistry with arrays of nanosized electrodes, such as double layer and quantum mechanical effects. On the other hand, frontier studies concerning the application of the NEE/NEA to the biomedical and neurochemical fields can open new tracks both to fundamental knowledge and application. 相似文献
28.
Zonghua Shi Yousef Mahdavian Yasamin Mahdavian Siavash Mahdigholizad Parisa Irani Mohammad Karimian Naser Abbasi Hori Ghaneialvar Akram Zangeneh Mohammad Mahdi Zangeneh 《Arabian Journal of Chemistry》2021,14(8):103224
Chitosan is a linear polysaccharide and non-toxic bioactive polymer with a wide variety of applications due to its functional properties such as ease of modification, and biodegradability. In this study, a green protocol for supporting of Cu(II) on chitosan-encapsulated magnetic Fe3O4 nanoparticles is described. The morphological and physicochemical features of the material were determined using several advanced techniques like fourier transformed infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), inductively coupled plasma (ICP), vibrating sample magnetometer (VSM) and X-ray photoelectron spectroscopy (XPS). The average diameter of the NPs was approximately 15–25 nm. In addition, the Fe3O/CS/Cu(II) nanocomposite was engaged in biological assays like study of anti-oxidant properties by DPPH mediated free radical scavenging test using BHT as a reference molecule. Thereafter, on having a significant IC50 value in radical scavenging assay, we extended the bio-application of the desired nanocomposite in anticancer study of lung well-differentiated bronchogenic adenocarcinoma, lung moderately differentiated adenocarcinoma, and lung poorly differentiated adenocarcinoma of human lung in-vitro conditions. In the cytotoxicity and anti-human lung studies, the nanocomposite was treated to lung cancer lung well-differentiated bronchogenic adenocarcinoma (HLC-1), lung moderately differentiated adenocarcinoma (LC-2/ad), and lung poorly differentiated adenocarcinoma (PC-14) cell line following MTT assay. The cell viability of malignant lung cell line reduced dose-dependently in the presence of Fe3O/CS/Cu(II) nanocomposite. The recent results suggest that Fe3O/CS/Cu(II) nanocomposite have a suitable anticancer activity against lung cell lines. 相似文献
29.
Bahram Yadollahi Valiollah Mirkhani Shahram Tangestaninejad Davud Karimian 《应用有机金属化学》2011,25(2):83-86
Herein, we want to report a simple and convenient way for protection‐deprotection of alcohols in the presence of ammonium decatungstocerate(IV) {(NH4)8[CeW10O36]·20H2O} as catalyst under ambient temperature in CH3CN. Using 0.002 mmol of the catalyst, various alcohols and phenols were transformed easily to the corresponding TMS ethers in excellent yields. In the second part, various TMS ethers were successfully converted to the parent hydroxyl compounds in the presence of the ammonium decatungstocerate(IV) catalyst. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
30.
Djozan Djavanshir Karimian Ghader Jouyban Abolghasem Iranmanesh Fahime Gorbanpour Hooshangh Alizadeh-Nabil Ali Akbar 《平面色谱法杂志一现代薄层色谱法》2014,27(4):274-280
JPC – Journal of Planar Chromatography – Modern TLC - This paper presents a new method based on thin-layer chromato-graphic separation, and image analysis (TLC-IA) of saffron colorant... 相似文献