Bandar Abbas, Iran
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Hashempour M.,Hormozgan University
Statistics, Optimization and Information Computing | Year: 2017

In this paper, the statistical evidences in lifetimes of dynamic r-out-of-n systems, which are modelled by sequential order statistics (SOS), are studied. Weak and misleading evidences in SOS for hypotheses concerning the population parameters are derived in explicit expressions and their behaviours with respect to the model parameters are investigated in details. Optimal sample sizes are provided while a minimum desired level for the decisive and the correct probabilities is given. It is shown that the optimal sample size does not depend on some model parameters. © 2017 International Academic Press.

The direct synthesis of 2-azetidinones from imines and carboxylic acids under mild conditions is developed. Dimethyl sulfoxide (DMSO) can be activated by acetic anhydride and the resulting active species is used for the in situ generation of ketenes from carboxylic acids. This method is cheap, simple, convenient, and efficient and the products are easily isolated. © 2014 Elsevier Ltd. All rights reserved.

N-p-Methoxyphenyl, N-p-ethoxyphenyl, N-4-methoxynaphth-1-yl, and N-p-methoxybenzyl 2-azetidinones readily undergo oxidative N-dearylation to afford NH-2-azetidinones using a silver(II)-persulfate complex. The ease of preparation and stability of the reagents, neutrality of the reaction medium, fast conversions, good-to-excellent yields of products, and the mildness of the reaction conditions are some advantages of this method. © 2013 Elsevier Ltd. All rights reserved.

Preparation of new types of modified poly(ether-imide-urethane)s, P O a-c and P S a-c, with good thermal stability and improved solubility was investigated. Two new bis(ether-azide)s bearing benzoxazole or benzothiazole pendent groups were synthesized by treating 2-[3,5-bis(4-trimellitimido-phenoxy)-phenyl]benzoxazole (1 O ), or 2-[3,5-bis(4-trimellitimido-phenoxy)-phenyl]benzothiazole (1 S ) with ethyl chloroformate in the presence of triethylamine, and subsequent by a nucleophilic reaction with sodium azide, respectively. Two series of modified polymers with moderate inherent viscosities between 0.21 and 0.32 dL g -1 were prepared from bis(ether-azide)s 2 O and 2 S with several aromatic diols in dry toluene under refluxing in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO, triethylenediamine) as a catalyst. The polycondensation reaction readily proceeded in desirable yields as one-pot reactions starting from 2 O to 2 S without the separate synthesis of the corresponding bis(ether-isocyanate)s. In addition, the corresponding unsubstituted poly(ether-imide-urethane)s, P R a-c, were prepared under identical experimental conditions for comparative purposes. All of the resulted polymers were thoroughly characterized by spectroscopic methods and thermogravimetry. The solubilities of modified polymer in common organic solvents as well as their thermal stability were enhanced compared to these of the corresponding unmodified polymers. The glass transition temperature, 10 % weight loss temperature and char yields at 800 C were, respectively, 13-28 C, 19-32 C and 3-7 % higher than those of the unmodified polymers. © 2013 Springer-Verlag Berlin Heidelberg.

Homaei A.,Hormozgan University
Journal of Molecular Catalysis B: Enzymatic | Year: 2015

Alkaline phosphatase was purified from Fenneropenaeus merguiensis from Persian Gulf to homogeneity level by using (NH4)2SO4 precipitation, DEAE-cellulose and DEAE-Sephadex anion-exchange chromatography and gel filtration chromatography. The molecular weight of the enzyme was 70 kDa, measured by SDS-PAGE. The alkaline phosphatase showed the strongest affinity with p-NPP as the substrate, and the highest catalytic efficiency for hydrolysis of the substrate at pH 11 and 50 °C. Activation energy (Ea) for catalysis of alkaline phosphatase was 8.3 kcal mol-1 K-1, while temperature quotient (Q10) was 3.25. It exhibited Michaelis-Menten kinetics with kcat of 95 s-1 and Km of 0.3 μM, respectively. Thermodynamic parameters for soluble p-NPP hydrolysis were as follows: ΔH# = 7.7 kcal mol-1 K-1, ΔG# = 14.7 kcal mol-1 K-1, ΔS# = -23.5 cal mol-1 K-1, ΔGE-S#=-0.7 kcal mol-1K-1 and ΔGE-T#=-3.4 kcal mol-1 K-1. Thermodynamic parameters (ΔH∗, ΔG∗, ΔS∗) for irreversible inactivation of alkaline phosphatase at different temperatures (35-50 °C) were also determined. © 2015 Elsevier B.V. All rights reserved.

Haveshki M.,Hormozgan University
Fuzzy Sets and Systems | Year: 2014

Borzooei et al. recently introduced the notion of associative filters in MTL-algebras and studied some of their properties. In this paper we prove that the only proper filter of MTL-algebra L that is associative according to their definition is L\{0}. In fact, in any MTL-algebra L if there exists a proper associative filter F in L then F=L\{0}. © 2013 Elsevier B.V. All rights reserved.

Homaei A.,Hormozgan University
International Journal of Biological Macromolecules | Year: 2015

Immobilization of papain was carried out by covalent attachment on Sepharose 6B activated by using cyanogen bromide. Immobilization process brought about significant enhancement of storage and thermal stability, stability at extreme pHs, and resistance against the inhibitory effects of various bivalent metal ions with respect to papain. The optimum temperature of papain increased by 20°C (from 60 to 80°C) and its optimum pH was shifted from 6.5 to 8.0 upon immobilization. The activation energy of the enzymatic reaction for immobilized papain showed a significant increase as compared with its free form (1.87kcalmol-1K-1 for free and 4.69kcalmol-1K-1 for immobilized enzyme). The kinetic parameters, Km and kcat, were estimated to be 0.62μM and 162×10-4s-1 for free and 0.79μM and 102×10-4s-1 for immobilized papain, respectively. © 2015 Elsevier B.V.

Zarei M.,Hormozgan University
Monatshefte fur Chemie | Year: 2013

The application and versatility of 2-fluoro-1-methylpyridinium p-toluenesulfonate as acid activator in the synthesis of several β-lactams under mild reaction conditions by use of ketene-imine cycloaddition reactions has been investigated. The effects of solvents, molar ratio of reagents, and temperature were considered. The method was also used for preparation of β-lactams substituted in position 3 by electron-withdrawing groups. The products are obtained in good to excellent yields. © 2013 Springer-Verlag Wien.

Zarei M.,Hormozgan University
Bulletin of the Chemical Society of Japan | Year: 2012

An efficient one-pot synthesis of β-lactams by the reaction of imines with acetic acid derivatives in the presence of DMF and benzoyl chloride adduct, a cheap reagent, has been described. Optimization of solvents, temperature, and molar ratio of reagent was also performed. Several types of β-lactams including monocyclic, spirocyclic, N-alkyl, 3-butadienyl, and 3-electron-withdrawing group have been synthesized by this method in good to excellent yields. All steps of the reaction proceed at room temperature. © 2012 The Chemical Society of Japan.

Zarei M.,Hormozgan University
Tetrahedron | Year: 2013

The Staudinger reaction of imines to β-lactams was successfully achieved with substituted acetic acid and phosphonitrilic chloride in one-pot under mild conditions. Several types of β-lactams, especially 3-electron-withdrawing group β-lactams, can be synthesized by this versatile and efficient method in good to excellent yields. This method is simple, clean, and the by-products were removed by simple aqueous work-up. The effects of solvents, molar ratio of reagent, and the temperature were considered. © 2013 Elsevier Ltd. All rights reserved.

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