排序方式: 共有327条查询结果,搜索用时 15 毫秒
311.
Somayeh Dianat Shahram Tangestaninejad Valiollah Mirkhani Majid Moghadam Iraj Mohammadpoor-Baltork 《Journal of the Iranian Chemical Society》2013,10(3):535-544
In this study, photocatalytic activity of InVO4 and InVO4–TiO2 nanoparticles in the degradation of aqueous solutions of industrial textile azo dyes such as Solophenyl Red 3BL, Coperoxon Nevy Blue RL and Black Nilusun 2BC (abbreviated as SR 3BL, CNB RL and BN 2BC, respectively) and also formaldehyde (abbreviated as FAD) under visible light and ultrasonic irradiations has been compared. The effect of various parameters such as pH, temperature, irradiation time, amounts of nanophotocatalyst and nanocomposite, and ultrasonic intensity on degradation rates was investigated. Then based on the Langmuir–Hinshelwood approach, reaction rates and adsorption equilibrium constants were calculated. The nanophotocatalyst and nanocomposite were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM) and UV‐Vis spectroscopic methods. It was observed that InVO4–TiO2 nanopowder was more reactive than pure InVO4 in the degradation of azo dyes under both conditions of visible light and ultrasonic irradiations. It was noticeable that degradation percent was more under ultrasonic irradiation rather than under visible light irradiation. 相似文献
312.
Bimetallic cobalt-ruthenium nano catalysts supported on carbon nanotubes(CNTs)are prepared using microemultion technique with water-to-surfactant ratios of 0.5—1.5.The nano catalysts were extensively characterized by different methods and their activity and selectivity in Fischer-Tropsch synthesis(FTS)have been assessed in a fixed-bed microreactor.The physicochemical properties and performance of the nanocatalysts were compared with the catalyst prepared by impregnation method.Very narrow particle size distribution has been produced by the microemulsion technique at relatively high loadings of active metals(15 wt%Co and 1 wt%Ru).According to TEM images,small Co particles(2—7 nm)were mostly confined inside the CNTs.Comparing with the catalyst prepared by impregnation,the use of microemulsion technique with water to surfactant ratio of 0.5 decreased the average cobalt oxide particle size to 4.8 nm,the dispersion was almost doubled and the reduction increased by 28%.Activity and selectivity were found to be dependent on the catalyst preparation method and water-to-surfactant ratio(as well as cobalt particle sizes).CO conversion increased from 59.1%to 75.1%and the FTS rate increased from 0.291 to0.372 gHC/(gcath).C5+liquid hydrocarbons selectivity decreased from 92.4%to 87.6%. 相似文献
313.
An extensive study of Fischer-Tropsch synthesis on nanostructure supports with high surface area such as nanostructure γ-alumina, single wall carbon nanotubes (SWNTs), and the hybrid of SWNTs/nanostructure γ-alumina has been investigated. The nanostructure γ-alumina was promoted with lanthanum to obtain better performance of catalyst and 15 wt% cobalt loading was the basis of our investigation. Fischer-Tropsch synthesis was performed in a fixed bed reactor under different reaction conditions (220–240 °C, 15–25 bar, H2/CO ratio of 2, GHSV of 900–1400) in order to study the effects of temperature, pressure and gas hourly space velocity (GHSV) changes on hydrocarbon selectivity and catalyst activity. The catalysts were extensively characterized by different methods including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), inductively coupled plasma (ICP), hydrogen (H2) chemisorption and temperature-programmed reduction (TPR). The results showed that the yield of hybrid supported catalyst (55.4%) is higher than that of nanostructure γ-alumina supported catalyst (55.0%) and lower than that of SWNTs supported cobalt catalyst (71.0%). The hybrid supported catalyst showed higher reduction degree and dispersion of cobalt particles. The temperature, pressure and GHSV effects on hybrid supported catalyst were studied and results showed that higher pressure favors the chain growth and temperature increase leads to the increases in methane selectivity and CO conversion. Higher hydrocarbon selectivity and CO conversion showed positive relationship with increasing GHSV while lower hydrocarbon selectivity diminishes. 相似文献
314.
The effects of a running gravitational coupling and the entropic force on future singularities are considered. Although it is expected that the quantum corrections remove the future singularities or change the singularity type, treating the running gravitational coupling as a function of energy density is found to cause no change in the type of singularity but causes a delay in the time that a singularity occurs. The entropic force is found to replaces the singularity type $II\, \hbox {by} \overline{III} (a=\hbox {const.}, H=\hbox {const.}, \dot{H} \rightarrow \infty , p \rightarrow \infty , \rho \rightarrow \infty )$ which differs from previously known type $III$ and to remove the $w$ -singularity. We also consider an effective cosmological model and show that the types $I$ and $II$ are replaced by the singularity type $III$ . 相似文献
315.
Somayeh Behrouz Mohammad Navid Soltani Rad Saeid Rostami Marzieh Behrouz Elham Zarehnezhad Ali Zarehnezhad 《Molecular diversity》2014,18(4):797-808
The synthesis and biological effects of 15 novel azole-bonded \(\upbeta \) -hydroxypropyl oxime \(O\) -ethers have been described. In this synthesis, the oximation of aromatic ketones followed by an \(O\) -alkylation reaction with epichlorohydrin and/or epibromohydrin led to the corresponding \(O\) -oxime ether adducts. Subsequently, the attained \(O\) -oxime ether adducts were used to synthesize the target molecules after treating them with the appropriate azole derivatives. The in vitro antifungal and antibacterial activities of title compounds were obtained against several pathogenic fungi, Gram-positive and/or Gram-negative bacteria. Benzophenone \(O\) -2-hydroxy-3-(2-phenyl-1 \(H\) -imidazol-1-yl) propyl oxime and 9 \(H\) -fluoren-9-one \(O\) -2-hydroxy-3-(2-phenyl-1 \(H\) -imidazol-1-yl)propyl oxime proved to have considerable antifungal activity against Candida albicans, Candida krusei, Aspergillus niger, and Trichophyton rubrum. These two compounds demonstrated comparable antifungal activity to clotrimazole and fluconazole (standard drugs). All compounds were also tested against Escherichia coli and Staphylococcus aureus as Gram-negative and Gram-positive bacteria, respectively, and their activities were compared to gentamycin and ampicillin (reference drugs). In general, marginal antibacterial activity against tested bacteria was observed for the title compounds. A molecular docking study is also discussed for the two most potent compounds against fungi. The docking study reveals a considerable interaction between the two most potent compounds and the active site of Mycobacterium P450DM. Moreover, these two compounds are much strongly bound to the active site of Mycobacterium P450DM compared to fluconazole. 相似文献
316.
First Report for Electrochemical Determination of Levodopa and Cabergoline: Application for Determination of Levodopa and Cabergoline in Human Serum,Urine and Pharmaceutical Formulations
下载免费PDF全文
![点击此处可从《Electroanalysis》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The electrochemical oxidation of levodopa on the surface of a carbon paste electrode modified with graphene nanosheets, 1‐(4‐bromobenzyl)‐4‐ferrocenyl‐1H‐[1,2,3]‐triazole (1,4‐BBFT) and hydrophilic ionic liquid (n‐hexyl‐3‐methylimidazolium hexafluoro phosphate) as a binder is studied. It has been found that the oxidation of levodopa at the surface of a modified electrode occurs at a potential of about 210 mV less positive than that of an unmodified carbon paste electrode (CPE). The prepared modified electrode exhibits a very good resolution of the voltammetric peaks of levodopa and cabergoline. The electrode has been applied successfully for the determination of levodopa and cabergoline in some real samples. 相似文献
317.
Iranpoor N Firouzabadi H Khalili D Motevalli S 《The Journal of organic chemistry》2008,73(13):4882-4887
The 2,2'-, 3,3'-, and 4,4'-azopyridines (azpy) and their alkyl pyridinium ionic liquids were studied as a new class of electron-deficient reagents for Mitsunobu esterification reactions. Among these compounds, 4,4'-azopyridine was found to be the most suitable one for esterification and thioesterification reactions. This new reagent promises to provide general and complementary solutions for separation problems in Mitsunobu reactions without restricting the reaction scope and facilitates the isolation of its hydrazine byproduct. The pyridine hydrazine byproduct can be simply recycled to its azopyridine by an oxidation reaction. 相似文献
318.
Mohammad Navid Soltani Rad Somayeh Behrouz Ali Khalafi-Nezhad 《Tetrahedron letters》2008,49(7):1115-1120
An efficient and selective method for esterification of alcohols using N-(p-toluenesulfonyl)imidazole (TsIm) is described. In this method, alcohols are refluxed with a mixture of RCO2Na (R: alkyl and aryl), TsIm, and triethylamine in the presence of catalytic amounts of tetra-n-butylammonium iodide (TBAI) in DMF to afford the corresponding esters in good yields. This methodology is highly efficient for various structurally diverse alcohols with selectivity for ROH: 1° > 2° > 3°. 相似文献
319.
Use of volatile organic solvents in headspace liquid‐phase microextraction by direct cooling of the organic drop using a simple cooling capsule
下载免费PDF全文
![点击此处可从《Journal of separation science》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Ali Reza Ghiasvand Fatemeh Yazdankhah Somayeh Hajipour 《Journal of separation science》2016,39(15):3011-3018
A low‐cost and simple cooling‐assisted headspace liquid‐phase microextraction device for the extraction and determination of 2,6,6‐trimethyl‐1,3 cyclohexadiene‐1‐carboxaldehyde (safranal) in Saffron samples, using volatile organic solvents, was fabricated and evaluated. The main part of the cooling‐assisted headspace liquid‐phase microextraction system was a cooling capsule, with a Teflon microcup to hold the extracting organic solvent, which is able to directly cool down the extraction phase while the sample matrix is simultaneously heated. Different experimental factors such as type of organic extraction solvent, sample temperature, extraction solvent temperature, and extraction time were optimized. The optimal conditions were obtained as: extraction solvent, methanol (10 μL); extraction temperature, 60°C; extraction solvent temperature, 0°C; and extraction time, 20 min. Good linearity of the calibration curve (R2 = 0.995) was obtained in the concentration range of 0.01–50.0 μg/mL. The limit of detection was 0.001 μg/mL. The relative standard deviation for 1.0 μg/mL of safranal was 10.7% (n = 6). The proposed cooling‐assisted headspace liquid‐phase microextraction device was coupled (off‐line) to high‐performance liquid chromatography and used for the determination of safranal in Saffron samples. Reasonable agreement was observed between the results of the cooling‐assisted headspace liquid‐phase microextraction high‐performance liquid chromatography method and those obtained by a validated ultrasound‐assisted solvent extraction procedure. 相似文献
320.
Characterizations of B and N heteroatoms as substitutional doping on structure,stability, and aromaticity of novel heterofullerenes evolved from the smallest fullerene cage C20: a density functional theory perspective
下载免费PDF全文
![点击此处可从《Journal of Physical Organic Chemistry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Somayeh Soleimani Amiri Maryam Koohi Behrooz Mirza 《Journal of Physical Organic Chemistry》2016,29(10):514-522
The structural stabilities and electronic properties of C20 fullerene and some its incorporated boron and nitrogen derivatives are probed at B3LYP/AUG‐cc‐pVTZ level of theory. According to density functional theory results, the topology of inserted B or N heteroatoms in [20]‐fullerene perturbs strongly the stability, energy, geometry, charge, polarity, nucleus‐independent chemical shifts, aromaticity, and highest‐occupied molecular orbital and lowest‐unoccupied molecular orbital (HOMO–LUMO) gap of the resulting heterofullerenes. Vibrational frequency (υmin) calculations show that except N10C10, all other BbNnC20‐(b + n) heterofullerenes with b, and n = 0, 4, 5, 8, and 10 are true minima. The calculated band gaps (?EHOMO–LUMO) of B8C12, and N8C12 (2.86 eV), show them the most stable heterofullerenes against electronic excitations. While 10 B substituting in equatorial position increase the conductivity of B10C10 through decreasing its band gaps, 10 N doping in equatorial position enhance stability of N10C10 against electronic excitations via increasing its band gaps. High natural bond orbital and Mulliken charge transfer on the surfaces of B atoms, especially B5N5C10with five B–N bonds in the equatorial position, provokes further investigation on its possible application for hydrogen storage. Nucleus‐independent chemical shift values show that B5N5C10 is the most aromatic species. The calculated heat of atomization per carbon (ΔHat/C) of B8C12 shows it the most thermodynamic stable heterofullerenes of each. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献