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191.
Ebrahim Ghanbari-Adivi Morteza Soltani 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2014,68(11):1-8
Harmonics with the photon energy of up to ~150 eV were studied using extended ablation plumes as the nonlinear media. The application of the ablation pulses of different duration covering the range between a few tens of femtoseconds and a few tens of nanoseconds revealed the advanced features of the extended plasmas produced by the subnanosecond pulses for efficient harmonic generation. The examples of the quasi-phase-matching of a group of harmonics in the plateau range and the advantages of using the two-color pump and cluster-containing plasmas are presented. We analyze the spatial and coherence characteristics of the high-order harmonics produced during propagation of the 64 fs pulse through the extended plasma plume produced by 370 ps pulses. It is shown that the divergence of plasma harmonics in the plateau range is 7 times smaller than the divergence of the driving radiation used for high-order harmonic generation. The measurements of the coherence properties of the lower-order harmonics showed that the visibility of interference fringes in the far field was in the range of 0.54–0.73. 相似文献
192.
A novel and highly efficient approach for the synthesis of aryl amides in high yields by the reaction of carboxylic acids and isocyanides in methanol at ambient temperature is reported. 相似文献
193.
M. A. Mohamed S. A. Halawy M. M. Ebrahim 《Journal of Thermal Analysis and Calorimetry》1994,41(2-3):387-404
The non-isothermal decomposition of cobalt acetate tetrahydrate was studied up to 500°C by means of TG, DTG, DTA and DSC techniques
in different atmospheres of N2, H2 and in air. The complete course of the decomposition is described on the basis of six thermal events. Two intermediate compounds
(i.e. acetyl cobalt acetate and cobalt acetate hydroxide) were found to participate in the decomposition reaction.
IR spectroscopy, mass spectrometry and X-ray diffraction analysis were used to identify the solid products of calcination
at different temperatures and in different atmospheres. CoO was identified as the final solid product in N2, and Co3O4 was produced in air. A hydrogen atmosphere, on the other hand, produces cobalt metal. Scanning electron microscopy was used
to investigate the solid decomposition products at different stages of the reaction. Identification of the volatile gaseous
products (in nitrogen and in oxygen) was performed using gas chromatography. The main products were: acetone, acetic acid,
CO2 and acetaldehyde. The proportions of these products varied with the decomposition temperature and the prevailing atmosphere.
Kinetic parameters (e.g.E and lnA) together with thermodynamic functions (e.g. °H, C
p and °S) were calculated for the different decomposition steps.
In celebration of the 60th birthday of Dr. Andrew K. Galwey 相似文献
194.
On the Fischer-Indole Reaction. II. Thermal and Acid Catalysed Indolization of 1′-Alkenyl-2′-methyl-2′-phenylacetohydrazides Seven different 1′-alkenyl-2′-methyl-2′-phenylacetohydrazides, 6a-g , have been prepared by treatment of the methylphenylhydrazones 7 of appropriate ketones and aldehydes with acetyl chloride in pyridine. At 170° 6a-g are transformed into the N-methylindoles 3a-g and acetamide in moderate yield. N-Methylaniline is the other major reaction product indicating that homolytic cleavage of the weak N, N-bond in 6 is a major primary reaction step. It is likely but not proven that the N-methylindoles 3 are formed in a reaction sequence initiated by an uncatalysed concerted [3, 3]-sigmatropic rearrangement. Upon treatment of 6 with 0.5N dichloroacetic acid in anhydrous acetonitrile at room temperature a quantitative conversion to 3 is observed, interpreted as proceeding by a charge induced [3, 3]-sigmatropic rearrangement of protonated 6 in the rate determining step. The ketone derivatives 6a-e (R1 = alkyl) react 40-1000 times faster with acid than the aldehyde derivatives 6f and 6g (R1 = H). This is rationalized as a consequence of the increased basicity of 6a-e relative to 6f and 6g caused by a steric effect. 相似文献
195.
Raheleh Bakhshi Ebrahim Vasheghani‐Farahani Hamid Mobedi Ahmad Jamshidi Mazyar Khakpour 《先进技术聚合物》2006,17(5):354-359
Biodegradable in situ forming drug delivery systems for naltrexone release are promising for post‐treatment of drug addicts. The effect of two different additives, glycerol and ethyl heptanoate, on the naltrexone hydrochloride release and solvent removal from a poly(DL ‐lactide‐co‐glycolide) (PLGA) injectable implant is presented in this article. The experimental results showed that the in vitro initial release of the drug was decreased in the presence of these additives. Ethyl heptanoate was, however, more effective than glycerol and increasing the amount of additives in PLGA solution up to 5% (w/w) resulted in a decrease of initial naltrexone release rate up to 50%. The morphological evaluation of implants using scanning electron microscopy indicated that the additives generated a less porous structure together with a finger‐like to sponge‐like transition. The solvent removal profiles of injectable implants, which can be well described by thermogravimetric and morphological analysis, were in good agreement with drug release profiles. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
196.
Ahmad Shaabani Ebrahim Soleimani Maria Darvishi 《Monatshefte für Chemie / Chemical Monthly》2007,138(1):43-46
Summary. The three-component condensation of aldehyde, N,N′-dimethylbarbituric acid and alkyl or aryl isocyanide afforded the corresponding furo[2,3-d]pyrimidine-2,4(1H,3H)-diones in 1-butyl-3-methylimidazolium bromide as an ionic liquid in high yields at room temperature within several minutes. 相似文献
197.
The 1:1 intermediate generated by the addition of an isocyanide to a dialkyl acetylenedicarboxylate is trapped by the iminium ion intermediate that forms from the reaction between an aromatic aldehyde and diethylamine. The reactions were completed in the presence of silica gel powder. The product dialkyl 2-[(alkylamino)carbonyl]-3-[(Z)-1-(diethylamino)-1-arylmethylidene]succinates, were produced in acceptable yields. The reactions are completely regio- and stereoselective. 相似文献
198.
Marzieh Anjomshoa Masoud Torkzadeh-Mahani Ebrahim Dashtrazmi Mahboubeh Adeli-Sardou 《Journal of fluorescence》2016,26(2):545-558
The focus of the present work is the preparation of new metal-based nanodrug to overcome limitations of chemotherapy such as poor water solubility of most common chemotherapeutic drugs. The copper(II) complex of 1,2,4-triazine derivatives, [Cu(dppt)2(H2O)2]2+ (dppt is 5,6-diphenyl- 3- (2-pyridyl)-1,2,4-triazine), has been synthesized at nano-size by sonochemical method and characterized by FTIR, zetasizer, and scanning electron microscopy (SEM). The interaction of the complex and nanocomplex with fish sperm DNA (FS–DNA) and BSA have been investigated under physiological conditions by a series of experimental methods. The results have indicated that the complex binds to FS–DNA by two biding modes, viz., electrostatic and intercalates into the base pairs of DNA. The competitive study with ethidium bromide (EB) shows that the complex and nanocomplex competes for the DNA–binding sites with EB. Protein binding studies show that the complex and nanocomplex could bind with BSA. The results of synchronous fluorescence of BSA show that additions of the complex affect the microenvironment of both tyrosine and tryptophan residues during the binding process. The in vitro cytotoxicity of the complex (solution in DMSO) and nanocomplex (colloid in H2O) against the human carcinoma cell lines (MCF-7 and A-549) was evaluated by MTT assay. The results of in vitro cytotoxicity indicate that the complex and nanocomplex have excellent cytotoxicity activity against MCF-7 and A-549. Results of the microscopic analyses of the cancer cells confirm the results of the cytotoxicity. 相似文献
199.
Abbas Shockravi Ali Yousefi Samad Bavili Tabrizi Masoomeh Zakeri Ebrahim Abouzari‐Lotf Hashem Sharghi 《Journal of heterocyclic chemistry》2008,45(2):319-322
200.
Ahmad Shaabani Fahimeh Rezazadeh Ebrahim Soleimani 《Monatshefte für Chemie / Chemical Monthly》2008,139(8):931-933
Ammonium chloride as a very inexpensive and readily available reagent efficiently catalyzes one-pot, three-component Groebke condensation reactions of aldehydes, isocyanides, and 2-aminopyridines or 2-aminopyrimidines in methanol to afford the corresponding
imidazo[1,2-a]pyridines in high yields at room temperature.
Correspondence: Ahmad Shaabani, Department of Chemistry, Shahid Beheshti University, PO Box 19396-4716, Tehran, Iran. 相似文献