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381.
Alizadeh M. H. Razavi H. Farrash Bamoharram F. Hassanzadeh M. K. Khoshnavazi R. Mohammadi Zonoz F. 《Kinetics and Catalysis》2003,44(4):524-528
Sodium 30-tungstopentaphosphate, the so-called Preyssler's anion with a formula of [NaP5W30O110]14– (I) catalyzes the acetylation of alcohols (C
n
H2n + 1OH, n = 2, 3, 4, 5) with acetic acid. High yield is obtained with I as pure acid or supported on silica. Both homogeneous and heterogeneous catalysts are discussed and compared. H14[NaP5W30O110], abbreviated as H14-P5, under homogeneous conditions, as well as supported on silica (heterogeneous conditions) is found to be an excellent catalyst. Our data indicate that, when the ammonium salt of I is employed as the catalyst, the yield increases as the alcohol carbon-chain is increased. This behavior is found to be quite general. The catalysts can be easily recovered and recycled with retention of their initial structure and activity. 相似文献
382.
A simple and appropriate procedure for the synthesis of 4,5‐dihydro‐5‐hydroxy‐3H‐pyrrole‐3,3‐dicarbonitrile derivatives is reported. The advantages of this method are one‐pot conditions, high yield of products, short reaction times, and no need of metal catalyst. The structures are confirmed spectroscopically (IR, 1H‐ and 13C‐NMR, and EI‐MS) and by elemental analyses. A plausible mechanism for this reaction is proposed (Scheme 2). 相似文献
383.
Development of an ultrasound‐assisted emulsification microextraction method for the determination of chlorpyrifos and organochlorine pesticide residues in honey samples using gas chromatography with mass spectrometry
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Mir‐Michael Mousavi Seyedrafie Arefhosseini Ali Akbar Alizadeh Nabili Mansour Mahmoudpour Mahboob Nemati 《Journal of separation science》2016,39(14):2815-2822
A simple, rapid, and efficient ultrasound‐assisted emulsification microextraction method followed by gas chromatography mass spectrometry in selected ion monitoring mode was developed for the determination of organochlorine pesticides in honey samples. The type and volume of organic extraction solvent, pH, effect of added salt content, and centrifuging time and speed were investigated. Under the optimum extraction conditions, 30 μL of 1, 2‐dibromoethane (extraction solvent) was immersed into an ultrasonic bath for 1 min at 40°C. The limits of detection and quantification for all target pesticides were 0.003–0.06 and 0.01–0.2 ng/g, respectively. The extraction recovery was 91–100% and the enrichment factors were 168–192. The relative standard deviation for the method was <6% for intraday (n = 6) and <8% for interday precision (n = 4). The proposed method was successfully applied for the analysis of organochlorine pesticides in honey samples. 相似文献
384.
Abdus?Saboor Morad?Alizadeh Muhammad?Nauman?KhanEmail author Indranil?Ghosh Gauss?M.?Cordeiro 《Mediterranean Journal of Mathematics》2017,14(2):96
We introduce and study a new distribution called the odd log-logistic modified Weibull (OLLMW) distribution. Various of its structural properties are obtained in terms of Meijer’s G-function, such as the moments, generating function, conditional moments, mean deviations, order statistics and maximum likelihood estimators. The distribution exhibits a wide range of shapes varying skewness and takes all possible forms of hazard rate function. We fit the OLLMW and some competitive models to two data sets and prove empirically that the new model has a superior performance among the compared distributions as evidenced by some goodness-of-fit statistics. 相似文献
385.
386.
Alizadeh Pahlavani M. R. Mohammadpour H. A. Shoulaie A. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2010,38(2):113-120
387.
We present a summary of methods based on semidefinite programming for estimating arrival rate of nonhomogeneous Poisson processes from a finite set of observed data. Both one-dimensional time dependent, and multi-dimensional time and location dependent rates are considered. The arrival rate is a nonnegative function of time (or time and location). We also assume that it is a smooth function with continuous derivatives of up to certain order k. We estimate the rate function by one or multi-dimensional splines, with the additional condition that the underlying rate function is nonnegative. This approach results in an optimization problem over nonnegative polynomials, which can be modeled and solved using semidefinite programming. We also describe a method which requires only linear constraints. Numerical results based on e-mail arrival and highway accidents are presented. 相似文献
388.
Jocelyn J. Tindale Kurtis D. Hartlen Abdolhamid Alizadeh Prof. Mark S. Workentin Prof. Paul J. Ragogna Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(30):9068-9075
The synthesis and characterization of several compounds representing a new class of multitask‐specific phosphonium ionic liquids that contain a maleimide functionality is reported. The maleimide moiety of the ionic liquid (IL) is shown to undergo Michael‐type additions with substrates containing either a thiol or amine moiety, thus, serving as a template to introduce wide structural diversity into the IL. Multitask‐specific ILs are accessible by reaction of the maleimide with Michael donors that are capable of serving some function. As a model example to illustrate this concept, a redox active ferrocenyl thiol was incorporated and examined by cyclic voltammetry. Because the maleimide moiety is highly reactive to additions, the task‐specific ionic liquids (TSILs) are prepared as the furan‐protected Diels–Alder maleimide. The maleimide moiety can then be liberated when required by simple heating. 相似文献
389.
N. Alizadeh S. Ershad H. Naeimi H. Sharghi M. Shamsipur 《Analytical and bioanalytical chemistry》1999,365(6):511-515
A PVC membrane electrode for copper(II) ions based on a recently synthesized naphthol-derivative Schiff’s base as membrane carrier was prepared. The sensor exhibits a Nernstian response for Cu2+ ions over a wide concentration range (5.0 × 10–6–5.0 × 10–2 mol/L) with a detection limit of 3.1 × 10–6 mol/L (0.2 μg/mL). It has a very short response time of about 5 s and can be used for ¶3 months without any divergence in potential. The proposed electrode revealed good selectivities over a wide variety of other cations including alkali, alkaline earth, transition and heavy metal ions and could be used in a pH range of 4.0–7.0. It was successfully applied to the direct determination and potentiometric titration of copper ion. 相似文献
390.
Ebrahim Alizadeh Mousa Farhadi Kurosh Sedighi H.R. Ebrahimi-Kebria Akbar Ghafourian 《Communications in Nonlinear Science & Numerical Simulation》2009,14(3):724-733
The Adomian Decomposition Method is employed in the solution of the two dimensional laminar boundary layer of Falkner–Skan equation for wedge. This work aims at the solution of momentum equation in the case of accelerated flow and decelerated flow with separation. The Adomian Decomposition Method is provided an analytical solution in the form of an infinite power series. The effect of Adomian polynomials terms is considered on accuracy of the results. The velocity profiles in boundary layer are obtained. Results show a good accuracy compared to the exact solution. 相似文献