مجله علوم جمهوری اسلامی ایران
سال:1381 | دوره:13 | شماره:2 |تعداد مقالات:9

A novel quaternary ammonium-based cationic gemini surfactant (S6) having 1, 6 dibromo hexane as a spacer, have been used and its interaction with insulin in aqueous solution (pH, 7. 40) was investigated by several methods including fluorescence spectroscopy, UV-Vis spectroscopy, circular dichroism, dynamic light scattering, ζ-potential measurements, conductivity and transmission electron microscopy. Conductometry and fluorescence studies confirmed the complex formation between S6 and insulin. TEM micrographs revealed that the S6 micelles were of spherical shape with size distribution between 101-140 nm. The critical micelle concentration and some physicochemical properties were determined by conductance measurements. Fluorescence quenching studies in the presence of acrylamide indicated that in the protein-surfactant interaction the solvent accessibility of Tyr residues is reduced. Furthermore CD experiments (far-and near-UV CD) showed that, the content of alphahelix increases with increasing S6 concentration and some conformational changes occur in protein structure. The results from dynamic light scattering and ζ-potential measurements showed that insulin charge neutralization and hexamer dissociation take place in the presence of surfactant. Altogether, the S6 cationic Gemini surfactant can be considered as a candidate for insulin delivery.

A simple and green chemical procedure was reported for the synthesis of dihydropyrimidinones from various aldehydes, ethyl acetoacetate and urea or thiourea using holmium chloride as catalyst. The reactions were performed under solvent free conditions with ultrasound irradiation as the energy source. The advantages of this protocol include the excellent yield, operational simplicity, short time and the avoidance of the use of organic solvents and friendly preparation. Products were identified by mp. and IR, NMR and Mass spectroscopies.

A new magnetic nanocatalyst has been prepared using immobilization of vanadate onto aminopropyl functionalized SiO2/Fe3O4(VO3-/NH3 +-SiO2/Fe3O4). The obtained magnetic catalyst was characterized by FT-IR, XRD, VSM and SEM techniques and used for sulfoxidation of sulfide compounds to the correspondingsulfoxides in presence of H2O2 as oxidant at room temperature. The optimum of reaction conditions and reusability of catalyst have been investigated.

The spatangoid genus Schizaster Agassiz is recorded, for the first time, from the Lutetian (Middle Eocene) deposits of Sargaz area, south of Kerman, Iran. The Lutetian sediments of Sargaz region contain a rich and divers echinoid fauna represented by Cidaridae, Conoclypeidae, Echinolampadidae, Toxopneustidae, Phymosomatidae and Schizasteridae. Schizasteroid echinoids are an important component of this fauna. Five Schizasteroid echinoids assigned to genus Schizaster are described and illustrated in the present paper. The Schizaster species are Schizaster ambulacrum, S. archiaci, S. globulus, S. lucidus and S. spado. The Schizaster specimens occur in association with a rich nummulitids and alveolinids fauna, and macro-invertebrates consisting of bivalves and gastropods, which suggest a Lutetian age for the sediment. Associated micro-macro fauna also indicate a warm and shallow water environment was prevailed during the deposition of the sediments.

Marbles containing high-pressure mineral assemblage was found from the Sanandaj-Sirjan metamorphic belt in the Nahavand area in western Iran. The high-pressure marbles occur as small bodies or lenses within pelitic schist layers and show compositional banding of carbonate-and silicate-rich bands. Textural analysis revealed two metamorphic stages. The early stage is testified by relicts of the minerals such as rounded jadeite-bearing diopside, epidote (clinozoisite), amphibole 1 (pargasite-edenite) and titanite 1. The second stage (main stage) documented to have phlogopite, chlorite, amphibole 2 (tremolite) and titanite 2. P-T-XCO2 estimates for the early stage of metamorphism give an average pressure, temperature and XCO2 of 13. 5 kbar, 670 º C and 0. 35, whereas the second stage has been constrained at P=3. 8 kbar, T=500 º C and XCO2=0. 45. The high-pressure mineral assemblage documented in the Nahavand area, were formed during the subduction stage, while the second metamorphic blastesis were recorded during the exhumation event.

In this paper, we present an edge detection method based on wavelet transform and Hessian matrix of image at each pixel. Many methods which based on wavelet transform, use wavelet transform to approximate the gradient of image and detect edges by searching the modulus maximum of gradient vectors. In our scheme, we use wavelet transform to approximate Hessian matrix of image at each pixel, too. The main idea of our methods lies in the fact that, the direction of largest surface curvature is the eigenvector of the Hessian matrix corresponding to the largest absolute eigenvalue. Infact, we use the Hessian matrix's information to increase or decrease the effect of wavelet transform in and directions.

Suppose that G is a finite group. Then the set of all prime divisors of G is denoted by  (G) and the set of element orders of G is denoted by ( ) e  G. Suppose that ( ) e k   G. Then the number of elements of order k in G is denoted by k m and the sizes of the set of elements with the same order is denoted by nse  G ; that is,    : ( ) k e nse G  m k   G. In this paper, we prove that if G is a group such that nse  G  nse(Sz(n)), where n  32, 128 , then G  Sz(n). Here Sz(n) denotes the family of Suzuki simple groups, n  22k 1, k   . This proves that the second and third member of the family of Suzuki simple groups are characterizable by the set of the number of the same element order.

In this paper we introduce a generalization of M-small modules and discuss about the torsion theory cogenerated by this kind of modules in category  [M]. We will use the structure of the radical of a module in  [M] and get some suitable results about this class of modules. Also the relation between injective hull in  [M] and this kind of modules will be investigated in this article. For a module N   [M] we show that N is M-Rad if and only if ) ˆ (N Rad N  ; where Nˆ is the M-injective hull of N. We will show that for a   cohereditary module M, R[M] is closed under extension. Let M be a module and N   [M], the torsion theory cogenerated by R[M] is the reject of R[M] in N, defined as ( ) = { | } [ ] is M Rad X Re N X N N R M    . In this paper we study about the property of this torsion theory. We show that = ( ) [ ] N Re N R M if and only if for every nonzero homomorphism f: N  K in  [M], Im( f )  Rad(K). Another attractive result is = ( ) [ ] N Re N R M if and only if  (N, A) = 0, for all A  [M]. For a module N   [M] we show that if ( ) K Rad N K L  for some K  L  N, then the inclusion K  L is M-coRad and also if N  R[M] , then for every submodule L of N and McoRad inclusion K  L, we have ( ) K Rad N K L  . Finally for a pseudo projective module M we show that every N   [M] with Hom(M, N) = 0 is M-Rad and if moreover M  R[M] , then R[M] ={N   [M]| Hom(M, N) = 0}.