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1.
M. A. Nasseri S. A. Alavi B. Zakeri Nasab 《Journal of the Iranian Chemical Society》2013,10(2):213-219
A versatile, alternative and environmentally benign strategy for the synthesis of a series of pyrazoles has been successfully performed in water using PEG–SO3H as an acidic catalyst. The products are obtained in high yield from the one-pot reaction procedure involving dicarbonyl compounds and hydrazines/hydrazides. This new method totally avoids the use of organic acids and toxic or expensive solvents in this reaction. The catalyst is waste-free, easily prepared, and efficiently re-used. 相似文献
2.
In this paper, general properties of traveling salesman problem has been illustrated, then a model has been introduced to
minimize Make-span (time interval which all of jobs will be done) with considering sequence-dependence setup times and processing
time. Furthermore, fuzzy sets and its characteristics are applied to a Hard-solvable traveling salesman problem with considering
processing times. As it can be seen, traveling salesman problems are NP-hard, so solving problem in huge dimensions is uncontrollably
manageable and in other side these kinds of problems in real-world are unavoidable, so a local search can prove their importance.
(However this Meta-heuristic methods may not reveal exact optimal solution, but they yield a near-exact optimal solution in
undeniable reduced computational time). Here, some of most famous local searches have been explained in their common and normal
form, which are Genetic Algorithm (GA), Tabu Search (TS), Simulated Annealing (SA), Ant Colony System (ACO). In rest, a comprehensive
comparison through these methods has been shown. This normality in methods structure could help the article to hold no-side-taken
and acceptable judgments. In final, point methods analysis and parameter tuning are held. 相似文献
3.
In this paper, the results from a series of rheological tests of fresh pig kidney have been reported. Using a standard strain-controlled
rheometer, the oscillation strain sweep experiment showed a linear viscoelastic strain limit of the order of 0.2% strain.
To determine the components of dynamic moduli in terms of frequency, shear oscillation tests were done at strain 0.2% using
a stress-controlled rheometer. Shear stress relaxation tests were carried out with a fixed strain of 0.2% and 0.02 s rise
time. The model we have developed uses a multi-mode upper convected Maxwell (UCM) model with variable viscosities and time
constants, to which we have added a Mooney hyper-elastic response, both multiplied by a damping function. Different forms
of damping functions that control the non-linearity of strain-stress profile have been tested. The model was fitted to our
experimental data, and matched the entire test data reasonably well with a single set of parameters.
Received: 5 May 2000 Accepted: 16 March 2001 相似文献
4.
Ali Reza Ghiasvand Morasaalsadat Nasseri Sara Farsizaeh Mohammad Hadi Meshkatalsadat Reza Sadeghi-Sarabi Shahriar Shadabi Mohammad Borzoei 《Chromatographia》2011,73(9-10):1031-1035
Ultrasound-assisted headspace solid-phase microextraction (UA-HS-SPME) coupled to gas chromatography–mass spectrometry (GC–MS) has been used for analysis of volatile compounds in dry Tagetes minuta L. The highest extraction efficiency was achieved with a 100-μm polydimethylsiloxane (PDMS) fiber. Different experimental conditions, for example, type of fiber coating, sonication time, extraction time and temperature, and desorption time, were investigated. Thirty compounds were identified by use of this UA-HS-SPME–GC–MS method. Comparison of the method with the commonly used hydrodistillation (HD) method showed that the proposed method is simpler, needs much less sample, requires shorter extraction time and lower temperature, has high trapping ability, and extracts more volatile and thermally sensitive compounds. The major components identified by use of the method were e-ocimenone (10.3%), cis-β-ocimene (4.8%), α-terpinolene (8.4%), trans-caryophyllene (19.7%), germacrene-d (10.0%), and camphor (3.6%). 相似文献
5.
Nasseri Mohammad Ali Ramezani-Moghadam Simin Kazemnejadi Milad Allahresani Ali 《Research on Chemical Intermediates》2020,46(9):4233-4256
Research on Chemical Intermediates - A new multifunctional bimetallic nanocatalyst was prepared by immobilization of Cu/Ni-doped sulfated zirconium oxide on magnetic cadmium ferrite... 相似文献
6.
Chlorophyll b was extracted from Heliotropium europaeum plant, then immobilized on magnetic nanoparticles (Fe3O4@SiO2@Chl-Mg) and found as an efficient and green catalyst for the preparation of a variety of benzimidazoles and spirooxindoles in mild conditions. The catalyst was fully characterized by Fourier-transform infrared (FTIR), ultraviolet–visible (UV–vis) spectroscopy, X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), thermogravimetric (TGA), vibrating sample magnetometer (VSM), transmission electron microscopy (TEM), and dynamic light scattering (DLS) analyses. To prove the catalytic influence of Mg over the reactions, the catalytic activity of the demetalated chlorophyll b as well as some other control experiments was investigated. High to excellent yields were achieved for all entries, whether benzimidazole or spirooxindole derivatives at short reaction times. The catalyst could be recovered and reused for several consecutive runs by a simple external magnetic field without any considerable reactivity loss. The properties of the recovered catalyst were investigated by various analyses. Finally, the reasonable mechanisms were proposed for the reactions based on the literature. 相似文献
7.
The preparation, characterization and catalytic application of Co (III) salen complex loaded on cobalt ferrite‐silica nanoparticle [CoFe2O4@SiO2@ Co (III) salen complex] are described. Co (III) salen complex loaded on ferrite cobalt‐silica nanoparticles is characterized by transmission electron microscopy, scanning electron microscopy coupled with energy‐dispersive X‐ray, vibrating‐sample magnetometer and Fourier transform‐infrared analyses. The thermal stability of the material is also determined by thermal gravimetric analysis. An average crystallite size is determined from the full‐width at half‐maximum of the strongest reflection by using Scherrer's approximation by powder X‐ray diffractometry. The efficiency of CoFe2O4@SiO2@Co (III) salen complex is investigated in the synthesis of spirooxindoles of malononitrile, various isatins with 1,3‐dicarbonyles. The nanocatalyst demonstrated excellent catalytic activity that gave the corresponding coupling products in good to excellent yields. Moreover, the recoverability and reusability of CoFe2O4@SiO2@Co (III) salen complex is investigated where nanocatalyst could be recovered and reused at least five times without any appreciable decrease in activity and selectivity, which confirmed its high efficiency and high stability under the reaction conditions and during recycling stages. 相似文献
8.
Milad Kazemnejadi Seyyedeh Ameneh Alavi G. Zinat Rezazadeh Mohammad Ali Nasseri Ali Allahresani Mohsen Esmaeilpour 《应用有机金属化学》2020,34(2):e5388
Cu(II) Schiff base complex supported on Fe3O4@SiO2 nanoparticles was employed as a magnetic nanocatalyst (nanocomposite) with a phase transfer functionality for the one-pot preparation of α-aminonitriles (Strecker reaction). The desired α-aminonitriles were obtained from the reaction of aromatic or aliphatic aldehydes, aniline or benzyl amine, NaCN, and 1.6 mol% of the catalyst in water at room temperature and good to excellent yields were obtained for all substrates. The catalyst was characterized analytically and instrumentally including Fourier-transform infrared spectroscopy, X-ray diffraction, thermogravimetric, nuclear magnetic resonance, energy-dispersive X-ray spectroscopy, inductively coupled plasma spectroscopy, vibrating-sample magnetometry analysis, dynamic light scattering, Brunauer–Emmett–Teller surface area, field emission scanning electron microscopy, and transmission electron microscopy analyses. The reaction mechanism was investigated, in which the performance of the catalyst as a phase transition factor seems to be probable. The catalyst showed high activity, high turnover frequency (TOF)s, significant selectivity, and fast performance toward the Strecker synthesis. The nanocatalyst can be readily and quickly separated from the reaction mixture with an external magnet and can be reused for at least seven successive reaction cycles without significant reduction in efficiency. 相似文献
9.
A Mechanism‐Based Approach to Screening Metagenomic Libraries for Discovery of Unconventional Glycosidases
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Seyed Amirhossein Nasseri Dr. Leo Betschart Daria Opaleva Dr. Peter Rahfeld Prof. Stephen G. Withers 《Angewandte Chemie (International ed. in English)》2018,57(35):11359-11364
Functional metagenomics has opened new opportunities for enzyme discovery. To exploit the full potential of this new tool, the design of selective screens is essential, especially when searching for rare enzymes. To identify novel glycosidases that employ cleavage strategies other than the conventional Koshland mechanisms, a suitable screen was needed. Focusing on the unsaturated glucuronidases (UGLs), it was found that use of simple aryl glycoside substrates did not allow sufficient discrimination against β‐glucuronidases, which are widespread in bacteria. While conventional glycosidases cannot generally hydrolyze thioglycosides efficiently, UGLs follow a distinct mechanism that allows them to do so. Thus, fluorogenic thioglycoside substrates featuring thiol‐based self‐immolative linkers were synthesized and assessed as selective substrates. The generality of the approach was validated with another family of unconventional glycosidases, the GH4 enzymes. Finally, the utility of these substrates was tested by screening a small metagenomic library. 相似文献
10.
Zakerinasab B. Nasseri M. A. Hassani H. Samieadel M. M. 《Research on Chemical Intermediates》2016,42(4):3169-3181
Research on Chemical Intermediates - Sulfamic acid supported on Fe3O4@SiO2 superpara magnetic nanoparticles was successfully applied as a recyclable solid acid catalyst with a large density of... 相似文献