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131.
The physical and mechanical properties of blends composed of two kinds of epoxy resins of different numbers of functional groups and chemical structure were studied.One of the resins was a bifunctional epoxy resin based on diglycidyl ether ofbisphenol A and the other resin was a multifunctional epoxy novolac resin.Attempt was made to establish a correlation between the structure and the final properties of cured epoxy samples.The blend samples containing high fraction of multifunctional epoxy resin showed higher solvent resistance and lower flexural modulus compared with the blends containing high fraction of bifunctional epoxy resin.The epoxy blends showed significantly higher ductility under bending test than the neat epoxy samples.The compressive modulus and strength increased with increasing of multifunctional epoxy in the samples,probably due to enhanced cross-link density and molecular weight.Morphological analysis revealed the presence of inhomogeneous sub-micrometer structures in all samples.The epoxy blends exhibited significantly higher fracture toughness (by 23% at most) compared with the neat samples.The improvement of the fracture toughness was attributed to the stick-slip mechanism for crack growth and activation of shear yielding and plastic deformation around the crack growth trajectories for samples with higher content of bifunctional epoxy resin as evidenced by fractography study. 相似文献
132.
Morteza Hosseini Mehdi Khoobi Roghayeh Tarasi Mohammad Reza Ganjali 《Research on Chemical Intermediates》2018,44(9):5031-5042
A rhodamine-conjugated coumarin (L) was used in designing a selective fluorescence chemosensor for the determination of trace amounts of Cr3+ ions in acetonitrile–water (MeCN/H2O (90:10, %v/v) solutions. The intensity of the fluoresce emission of the chemosensor is intensified upon addition of Cr3+ ions in MeCN/H2O (90:10, %v/v) solutions, due to the formation of a selective 1:1 complex between L and Cr3+ ions. The fluorescence enhancement versus Cr3+ concentration has been found to be linear from 1.0?×?10?7 to 1.8?×?10?5 M and a detection limit of 7.5?×?10?8 M. The proposed fluorescent probe proved to be highly selective towards Cr3+ ions as compared to other common metal ions and could be successfully applied to the determination of Cr3+ concentrations in some water and wastewater samples. 相似文献
133.
An efficient green approach for the synthesis of N-cyclohexyl-3-aryl-quinoxaline-2-amine derivatives, via a three-component one-pot condensation reaction of o-phenylenediamine, aromatic aldehydes and cyclohexyl isocyanide in the presence of perlite–SO3H nanoparticles (diameter/thickness of platelets <?100 nm) under ultrasound irradiation has been demonstrated. The present method offers advantages such as shorter reaction time, easy work-up, excellent yields, recovery and reusability of catalyst. In addition, the methodology has been prosperous in getting the green chemistry purposes such as natural catalyst, using ultrasound irradiation instead of conventional heating and stirring, and a non-hazardous products in the thus combining the features of both economic and environmental advantages. 相似文献
134.
The solid–liquid equilibria of a poorly water-soluble antioxidant agent namely naringoside were assayed to determine solubility in binary liquid mixtures of water?+?isopropanol (iso-PrOH) between 298.15 K and 320.15 K under atmospheric pressure. The mole fraction solubilities of naringoside in the saturated solution were determined using a combination of static shake-flask and ultraviolet spectrophotometry techniques. The dissolution behavior of naringoside was correlated with three solution models consisting of the van’t Hoff equation, the modified Apelblat equation and the Buchowski-Ksiazczak λH equation. The modified Apelblat equation was more consistent than the two other correlation models. Apparent thermodynamic analysis of naringoside dissolution was also performed at the mean harmonic temperature using the model parameters of the modified Apelblat equation. Furthermore, the Kamlet, Abboud and Taft Linear Solvation Energy Relationship (KAT-LSER) model was applied to analyze the effect of the solute–solvent intermolecular interactions on the solubility of this natural bioactive product. 相似文献
135.
Maryam Mohebbi Peyman Salehi Morteza Bararjanian Samad N. Ebrahimi 《Journal of the Iranian Chemical Society》2018,15(1):47-53
In this paper, synthesis of two derivatives of noscapine and their application as organocatalysts in the asymmetric addition of diethylzinc to aromatic aldehydes is reported. The first catalyst (2) was synthesized by the reduction of lactone ring of noscapine to form the corresponding diol, and the second one (3) was prepared by tert-butyl dimethyl silylation of the primary hydroxyl group of 2. Excellent yields and high ees up to 95% were obtained by using 3 as the catalyst. To the best of our knowledge, this is the first report on the application of lactone ring opened noscapinoid compounds as organocatalysts in asymmetric reactions. 相似文献
136.
Qamar Salamat Yadollah Yamini Morteza Moradi Meysam Safari Neda Feizi 《Journal of the Iranian Chemical Society》2018,15(2):293-301
In the present study, a simple versatile extraction method based on supramolecular solvent microextraction followed by inductively coupled plasma atomic emission spectrometry was developed for the extraction, separation and determination of zirconium (Zr) from hafnium (Hf). Zr and Hf were complexed with bis(2,4,4-trimethylpentyl) phosphinic acid, to obtain hydrophobic complex, and extracted into supramolecular solvent phase. The effective parameters on the supramolecular solvent microextraction efficiency were studied and optimized by using two different optimization methods: one variable at a time and central composite design. Under the optimum conditions, the linear range of 0.3–200.0 and 2.0–200.0 µg L?1, detection limits (S/N = 3) of 0.1 and 0.6 µg L?1, and precisions (n = 5) of 3.2–4.9% and 3.0–5.1% were obtained for Zr and Hf, respectively. Finally, the proposed method has been successfully applied for the extraction and separation of these cations in zirconium ore sample. 相似文献
137.
Shirazi Milad Shateri Alireza Bayareh Morteza 《Journal of Thermal Analysis and Calorimetry》2018,133(2):1061-1073
Journal of Thermal Analysis and Calorimetry - In the present paper, mixed convection heat transfer of water–Al2O3 nanofluid in the space between two cylinders is investigated numerically. The... 相似文献
138.
Ghobadi Nader Hafezi Fatemeh Naderi Sirvan Amiri Fatemeh Luna Carlos Arman Ali Shakoury Reza Ţălu Ştefan Rezaee Sahar Habibi Maryam Mardani Mohsen 《Semiconductors》2019,53(13):1751-1758
Semiconductors - The purpose of this research is to explore the properties of CoSe nanostructured thin films on glass substrates prepared by a chemical solution deposition method. Special attention... 相似文献
139.
Arezou Ostad‐Sharif Morteza Nikooghadam Dariush Abbasinezhad‐Mood 《International Journal of Communication Systems》2019,32(12)
Wireless body area networks (WBANs) are a network designed to gather critical information about the physical conditions of patients and to exchange this information. WBANs are prone to attacks, more than other networks, because of their mobility and the public channel they use. Therefore, mutual authentication and privacy protection are critical for WBANs to prevent attackers from accessing confidential information of patients and executing undetectable physical attacks. In addition, in the authentication and key agreement process, messages should be transferred anonymously such that they are not linkable. In this paper, we first indicate that one of the most recently introduced authentication protocol is vulnerable to the wrong session key agreement attack and desynchronization attack. Second, we propose a lightweight authentication and key agreement protocol, which can withstand the well‐known attacks and provide the anonymity feature. Eventually, we analyze the security of our proposed protocol using both Automated Validation of Internet Security Protocols and Applications (AVISPA) and random oracle model and compare its performance with the related works. The results demonstrate the superiority of our proposed protocol in comparison with the other protocols. 相似文献
140.
Sivakumar P. Nagaraju Regonda Samanta Debabrata Sivaram M. Hindia Mhd. Nour Amiri Iraj Sadegh 《Wireless Networks》2020,26(4):2317-2328
Wireless Networks - Nowadays, the smart grid has demonstrated a great ability to make life easier and more comfortable given recent advances. This paper studies the above issue from the perspective... 相似文献