Abbasi H.,Jundi-Shapur University of Technology |
Noghabi K.A.,Iran National Institute of Genetic Engineering and Biotechnology |
Ortiz A.,University of Murcia
Chemistry and Physics of Lipids | Year: 2012
This work presents a biophysical study on the interactions of a monorhamnolipid (monoRL) produced by Pseudomonas aeruginosa MA01 with model phosphatidylcholine membranes. The molecular characterization of the biological activities, including the modulation of phospholipid membranes structure, of this monoRL biosurfactant is of importance for the validation of this particular Pseudomonas aeruginosa strain as a useful biosurfactant producer. The marked amphiphilic structure of monoRL is expected to result in strong interactions with the phospholipid constituents of membrane bilayers. Incorporation of monoRL into DMPC completely abolished the pretransition, and the main gel to liquid-crystalline phase transition was progressively broadened and shifted to lower temperatures, as observed by differential scanning calorimetry. Partial phase diagrams for DPPC and DSPC indicated near-ideal behavior. However, the DMPC diagram indicated fluid phase immiscibility. X-ray diffraction showed and apparent increase in d-value for DPPC containing monoRL, which might be the result of an effective increase in the bilayer thickness, or in the thickness of the hydration layer between bilayers. FTIR indicated that interaction of monoRL with the phospholipid acyl chains did not result in a large additional disordering of the acyl chain region of the fluid bilayer. Analysis of the CO stretching band of DPPC indicated an important effect of monoRL on the interfacial region of phosphatidylcholine bilayers, which might contribute to explain some of the biological activities of this glycolipid. © 2012 Elsevier Ireland Ltd. All rights reserved.
Pourjavadi A.,Sharif University of Technology |
Zeidabadi F.,Sharif University of Technology |
Barzegar Sh.,Jundi-Shapur University of Technology
Journal of Applied Polymer Science | Year: 2010
Novel types of highly swelling hydrogels were prepared by grafting crosslinked polyacrylamide-co-poly-2-acrylamido-2-methylpropane sulfonic acid (PAAm-co-PAMPS) chains onto sodium alginate (Na-Alg) through a free radical polymerization method. The superabsorbent formation was confirmed by Fourier transform infrared spectroscopic (FTIR). The controlled release behavior of diclofenac sodium (DS) from superabsorbent polymer was factinvestigated, and shown that the release profiles of DS from superabsorbent polymer were slow in simulated gastric fluid (SGF, pH 1.2) over 3 h, but nearly all of the initial drug content was released in simulated intestinal fluid (SIF, pH 7.4) within 21 h after changing media. Overall the results demonstrated that biodegradable superabsorbent could successfully deliver a drug to the intestine without losing the drug in the stomach, and could be potential candidates as an orally administrated drug delivery system. © 2010 Wiley Periodicals, Inc.
Tahmasebi N.,Jundi-Shapur University of Technology |
Mahdavi S.M.,Sharif University of Technology
Applied Surface Science | Year: 2015
In this study, colloidal tungsten oxide nanoparticles were fabricated by pulsed laser ablation of tungsten target using the first harmonic of a Nd:YAG laser (1064 nm) in deionized water. After ablation, a 0.33 g/lit HAuCl4 aqueous solution was added into as-prepared colloidal nanoparticles. In this process, Au3+ ions were reduced to decorate gold metallic state (Au0) onto colloidal tungsten oxide nanoparticles surface. The morphology and chemical composition of the synthesized nanoparticles were studied by AFM, XRD, TEM and XPS techniques. UV-Vis analysis reveals a distinct absorption peak at ∼530 nm. This peak can be attributed to the surface plasmon resonance (SPR) of Au and confirms formation of gold state. Moreover, X-ray photoelectron spectroscopy reveals that Au ions' reduction happens after adding HAuCl4 solution into as-prepared colloidal tungsten oxide nanoparticles. Transmission electron microscope shows that an Au shell has been decorated onto colloidal WO3 nanoparticles. Noble metal decorated tungsten oxide nanostructure could be an excellent candidate for photocatalysis, gas sensing and gasochromic applications. Finally, the gasochromic behavior of the synthesized samples was investigated by H2 and O2 gases bubbling into the produced colloidal Au/WO3 nanoparticles. Synthesized colloidal nanoparticles show excellent coloration contrast (∼80%) through NIR spectra. © 2015 Elsevier B.V. All rights reserved.
Keramat A.,Jundi-Shapur University of Technology |
Kolahi A.G.,Shahrood University of Technology |
Ahmadi A.,Shahrood University of Technology
Journal of Fluids and Structures | Year: 2013
Poisson's ratio in viscoelastic materials is a function of time. However, recently developed waterhammer models of viscoelastic pipes consider it constant. This simplifying assumption avoids cumbersome calculations of double convolution integrals which appear if Poisson's ratio is time-dependent. The present research develops a mathematical model taking the time dependency of Poisson's ratio into account for linear viscoelastic pipes. Poisson's ratio is written in terms of relaxation function and bulk modulus which is assumed to be constant. The relaxation function is obtained from creep function given as the viscoelastic property data of pipe material. The results obtained from the present waterhammer model are compared with the experimental data for two different flow rates. The comparison reveals that with the application of the time-dependent Poisson's ratio and unsteady friction, the viscoelastic data of mechanical tests can directly be used for waterhammer analysis with less need for the calibration of the flow configuration. It was also shown that the creep curve calibrated based on the present model is closer to the actual creep curve than that calibrated based on previous models. © 2013.
Maleki B.,Hakim Sabzevari University |
Barzegar S.,Jundi-Shapur University of Technology |
Sepehr Z.,Hakim Sabzevari University |
Kermanian M.,Hakim Sabzevari University |
Tayebee R.,Hakim Sabzevari University
Journal of the Iranian Chemical Society | Year: 2012
A simple, efficient, and environmentally benign route was developed for the preparation of 14-aryl or alkyl- 14H-dibenzo[a,j]xanthene, 1,8-dioxo- octahydroxanthene and 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthene-11-ones from condensation of various aldehydes with (i) β-naphthol, (ii) cyclic 1,3-dicarbonyl compounds and (iii) β-naphthol and cyclic 1,3-dicarbonyl compounds, using novel polymeric catalyst [poly(AMPS-co-AA)] under solvent-free conditions. Use of easily available catalyst, shorter reaction times, better yields, simplicity of the reaction, heterogeneous system, and easy work-up are the advantages of the present method. © Iranian Chemical Society 2012.