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61.
Abbas Shockravi Shahram Mehdipour-Ataei Masoomeh Zakeri 《European Polymer Journal》2007,43(2):620-627
A new-type of sulfide containing diacid (1,1′-thiobis(2-naphthoxy acetic acid)) was synthesized from 2-naphthol in three steps. Reaction of 2-naphthol with sulfur dichloride afforded 1,1′-thiobis(2-naphthol) (TBN). 1,1′-Thiobis(2-naphthoxy acetic ester) (TBNAE) was successfully synthesized by refluxing the TBN with methylcholoroacetate in the presence of potassium carbonate. The related diacid was synthesized by basic solution reduction of TBNAE. The obtained diacid was fully characterized and used to prepare novel thermally stable poly(sulfide ether amide)s via polyphosphorylation reaction with different aromatic diamines. The properties of these new polyamides were investigated and compared with similar polyamides. These polyamides showed inherent viscosities in the range of 0.39-0.87 dL g−1 in N,N-dimethylacetamide (DMAc) at 30 °C and at a concentration of 0.5 g dL−1. All the polyamides were readily soluble in a variety of polar solvents such as DMAc and tetrahydrofuran (THF). These polyamides showed glass transition temperature (Tg) between 241-268 °C. Thermogravimetric analysis measurement revealed the decomposition temperature at 10% weight loss (T10) ranging from 441- 479 °C in argon atmosphere. 相似文献
62.
Rostampour Malihe Aboudzadeh Mohammadreza Sadeghi Mahdi Hamidi Saeid Alirezapour Behroz Soltani Naser Aslani Gholamreza 《Journal of Radioanalytical and Nuclear Chemistry》2017,314(3):1759-1766
Excitation functions and theoretical yields via charge particle induced reactions were evaluated using EMPIRE-3.2.2 and ALICE/ASH codes and the obtained results have been discussed and compared with the available reported experimental data. It has been verified that natCu(p,n)65Zn reaction is the optimum 65Zn production route. The 65Zn was produced using natCu(p,xn) 65Zn reaction in the energy range of 16.8 → 12.2 MeV with the thick target yield of 0.15 ± 0.005 MBq/μA h. The 65Zn radionuclide was purified by anion exchange chromatography.
相似文献63.
In this study, a chiral stability-indicating CE assay was developed for the stability evaluation of tramadol (TR) enantiomers in commercial tablets using maltodextrin as chiral selector. To investigate the stability-indicating power of the analytical method as well as stability evaluation of TR enantiomers, active pharmaceutical ingredient and TR tablets were subjected to photolysis, heat, oxidation and hydrolysis to conduct stress testing. Best separation for the TR enantiomers was achieved on an uncoated fused-silica capillary at 20 °C using borate buffer (50 mM, pH 10.2) containing 10% m/v maltodextrin. All determinations were performed by a UV detector at 214 nm. A constant voltage of 20 kV was applied to obtain the separation. The range of quantitation for both enantiomers was 5-100 μg/mL (R>0.996). Intra- and inter-day RSD (n=6) were less than 10%. The percent relevant errors were obtained to be less than 4.0 for both enantiomers. The limits of quantitation and detection for both enantiomers were 5 and 1.5 μg/mL, respectively. Degradation products resulting from the stress studies were the same for both enantiomers and did not interfere with the detection of the enantiomers. 相似文献
64.
Masoumeh Zakeri Majid M. Heravi Mina Saeedi Narges Karimi Hossein A. Oskooie Niloofar Tavakoli‐Hoseini 《中国化学》2011,29(7):1441-1445
An efficient one‐pot condensation of β‐naphthol, aldehydes and cyclic 1,3‐dicarbonyl compound has been achieved with ionic liquids as catalyst, thus a variety of 8,9,10,12‐tetrahydrobenzo[a]xanthen‐11‐one derivatives were prepared in good yields. The present approach offers several advantages such as shorter reaction times, good yields and mild reaction conditions. 相似文献
65.
Bardajee Ghasem Rezanejade Zamani Mohammadreza Sharifi Mahdieh Rezanejad Habib Motallebi Mostafa 《Journal of fluorescence》2022,32(5):1959-1967
Journal of Fluorescence - A novel cyanine 3 (Cy3)-based bio-conjugated sensor has been developed to detect target DNA or extracted RNA from COVID -19 samples using the fluorescence resonance energy... 相似文献
66.
A simple, inexpensive, environmentally friendly and efficient route for the acylation of a number of alcohols, phenols and amines using pentafluorophenylammonium triflate (PFPAT) as a catalyst is described. PFPAT organocatalyst is air-stable, cost-effective, easy to handle, and easily removed from the reaction mixtures. 相似文献
67.
Patrick W. Fowler Mohammadreza Jooyandeh Gunnar Brinkmann 《Journal of mathematical chemistry》2012,50(8):2272-2280
According to the face-spiral conjecture, first made in connection with enumeration of fullerenes, a cubic polyhedron can be reconstructed from a face sequence starting from the first face and adding faces sequentially in spiral fashion. This conjecture is known to be false, both for general cubic polyhedra and within the specific class of fullerenes. Here we report counterexamples to the spiral conjecture within the 19 classes of cubic polyhedra with positive curvature, i.e., with no face size larger than six. The classes are defined by triples {p 3, p 4, p 5} where p 3, p 4 and p 5 are the respective numbers of triangular, tetragonal and pentagonal faces. In this notation, fullerenes are the class {0, 0, 12}. For 11 classes, the reported examples have minimum vertex number, but for the remaining 8 classes the examples are not guaranteed to be minimal. For cubic graphs that also allow faces of size larger than 6, counterexamples are common and occur early; we conjecture that every infinite class of cubic polyhedra described by allowed and forbidden face sizes contains non-spiral elements. 相似文献
68.
The train formation plan (TFP) determines routing and frequency of trains, and assigns the demands to trains. In this paper, an improved local branching algorithm is proposed for the TFP model in Iranian railway. This solution strategy is exact in nature, although it is designed to improve the heuristic behavior of the mixed integer programming (MIP) solver at hand. In the local branching algorithm, additional constraints are built in the model for the binary variables, but in the improved local branching algorithm, the additional constraints are built in the model for integer variables. A state-of-the-art method is applied for parameter tuning using design of experiments approach. To evaluate the proposed solution method, we have simulated and solved twenty test problems. The results show the efficiency and effectiveness of the proposed approach. The proposed algorithm is implemented for Iranian Railway network as a case study. 相似文献
69.
Ekaterina Leonova Jekabs Grins Mohammadreza Shariatgorji Leopold L. Ilag Mattias Edn 《Solid state nuclear magnetic resonance》2009,36(1):11-18
We compare 29Si magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectra from the two modifications of silicon nitride, α-Si3N4 and β-Si3N4, with that of a fully (29Si, 15N)-enriched sample 29Si315N4, as well as 15N NMR spectra of Si315N4 (having 29Si at natural abundance) and 29Si315N4. We show that the 15N NMR peak-widths from the latter are dominated by J(29Si–15N) through-bond interactions, leading to significantly broader NMR signals compared to those of Si315N4. By fitting calculated 29Si NMR spectra to experimental ones, we obtained an estimated coupling constant J(29Si–15N) of 20 Hz. We provide 29Si spin-lattice (T1) relaxation data for the 29Si315N4 sample and chemical shift anisotropy results for the 29Si site of β-Si3N4. Various factors potentially contributing to the 29Si and 15N NMR peak-widths of the various silicon nitride specimens are discussed. We also provide powder X-ray diffraction (XRD) and mass spectrometry data of the samples. 相似文献
70.
Milad Jahanshad Mohammadreza Manafi Seyed Mahmoud Mousavi-Safavi Seyed Saied Homami Majid Ghazanfarpour-Darjani 《Tetrahedron letters》2019,60(44):151216
A domino ring opening/cross-coupling reaction of oxiranes with terminal alkynes and aryl iodides has been developed. This transformation serves as a protocol for the synthesis of homo-alkyne ether skeletons from the readily available starting materials. The success of the reaction has dependence on catalyst/ligand system of choice. The synthesis utility of the alkyne ether skeletons in formation of chromane skeleton has also been studied. 相似文献