modern research physics

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Nickelate with general formula La_2-xSr_xNiO₄ (x≈0.33) were synthesized by the sol–gel method. Then by changing the sintering temperature and growth parameters, particles with various sizes were produced. The crystal structure and physical properties of the prepared samples were investigated by X-ray diffraction (XRD), Fourier transform IR spectroscopy (FTIR), Energy dispersive X-ray spectroscopy (EDX) and field emission scanning electron microscopy (FE-SEM) and resistivity measurements from room temperature to low temperatures. The XRD results and investigation of the surface morphology show the lowest temperature to get a single phase tetragonal structure is 920°C. These data confirm the formation of single phase structure in samples sintered at higher temperatures. The particle size increases with increase in sintering temperature. The FE-SEM results show that the particles sizes are in range of 50nm to 2mm. The results of resistivity measurements versus temperature by fourprobe method indicate that the charge ordering transition temperature move to lower temperature with decrease in particle size. 

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In this paper, we studied the electronic conductance and energy gap of a graphene nano-ribbon which is connected to two semi-infinite atomic chains by the atoms located in the opposite sides of nano-ribbon. The numerical calculations were performed using the Green’s function method in the nearest neighbor approximation of tight-binding approach. The conductance curves plotted with respect to incoming electron energy show that for a zigzag graphene nano-ribbon with one benzene ring in its width, there is no gap in the energy band spectra of the system, while for the armchair case, an energy gap always exists around the Fermi energy and its value depends on the size of the nano-ribbon. The results show that the behavior of the graphene nano-ribbons conductance strongly depends on that how and where the leads connect to the nano-ribbon and on the contacts qualities.

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For this purpose 5 sampling stations namely as Astara, Bandar Anzali, Hashtpar, Chaboksar and Bandar Kiashahr were selected along the shoreline of the southwest Caspian. The maximum density was observed in 3-15 m depth. Catch composition from different sampling sites approve this statement. 0.41%, 2.24%, and 2.59% out of total catch was starry goby that came from Bandar Anzali, Chaboksar and Astara sampling stations respectively. This species did not observe in the Hashtpar and Bandar Kiashahr sampling stations. According to the results mean total length was 61.28±16.14 mm and mean weight was 3.16±0.92 gr. 

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In order to understand some physiological mechanism of chilling and cold sensitivity in plants we investigate the effects of chilling and cold stress on chlorophyll and proline content, lipid peroxidation and variable chlorophyll fluorescence (Fv/Fm) of Arabidopsis (thaliana L.) The four weeks-old plants (WT, and four chilling sensitive mutants [chs2-2], [chs2-1], [chs1-2] and [chs1-1]) were subjected to two different low temperature treatments (control (23^̊ C), chilling (13^̊ C) and cold (4^̊ C)), for one week. Fv/Fm and chlorophyll content changed significantly in all mutants except in WT by chilling stress (13^̊ C), compared with control and 4^̊ C treatments. Two out of four mutants, chs1-1 and chs1-2, had lowest chlorophyll content and Fv/Fm value among the tested genotypes. The proline content increased in all mutant genotypes, as well as in WT by chilling stress and 4^̊ C, compared with control. MDA content of shoots changed dramatically in all mutant genotypes except in WT by chilling stress, compared with control and 4^̊  C treatments. Our findings showed that two mutants, chs1-1 and chs1-2, have had highest chilling sensitivity among the tested genotypes and had the highest proline and MDA contents. It is possible that some damages in photosynthetic systems and/or in proline metabolism via mutation cause these plants more sensitive to chilling and cold stress

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During autumn and summer 2010 observed species from Amaranthus genus were studied in segetal and ruderal environments of Hamedan city. In this research, 100 plats randomly were selected and totally 6 species from Amaranthus were identified as neophyte wild elements: A. retroflexus L. A. lividus L., A. chlorostachys Willd, A. albus L., A. viridus L. and A. blitoides S. Watson. Dispersal of mentioned species in many segetal (such as farms and urban green spaces) and ruderal (such as wastelands, beside of walls and etc.) areas with remarkable dispersal, indicates suitable adaptation of this elements with antropogenic biotops. Among collected species, A. retroflexus L. with highest dispersal in farm lands and gardens, with H₅ (&alpha-euhemerob) hemeroby degree as a segetal plant and A. blitoides S. Watson.with H₆ (Polyhemerob) hemeroby degree in pavings and asphalts clef, as a severely ruderal plant are introduced from Hamedan city. other observed species of this genus, with H₄ (b-euhemerob) hemeroby degree more grow in beside of walls, gardens, urban green spaces and et

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In this article‎, ‎the efficient numerical methods for finding solution of the linear and nonlinear Fredholm integral equations of the second kind on base of Bernstein multi scaling functions are being presented‎. ‎In the beginning the properties of these functions‎, ‎which are a combination of block-pulse functions on ‎, ‎and Bernstein polynomials with the dual operational matrix are presented‎. ‎Then these properties are used for the purpose of conversion of the mentioned integral equation to a matrix equation that are compatible to a algebraic equations system‎. ‎The imperative of the Bernstein multi scaling functions are‎, ‎for the proper quantitative value of and have a high accuracy and specifically the relative errors of the numerical solutions will be minimum‎. ‎The presented methods from the standpoint of computation are very simple and attractive and the numerical examples which were presented at the end shows the efficiency and accuracy of these methods‎.

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In this paper, we study the Arens regularity properties of module actions and we extend some proposition from Baker, Dales, Lau and others into general situations. We establish some relationships between the topological centers of module actions and factorization properties of them with some results in group algebras. In 1951 Arens shows that the second dual of Banach algebra endowed with the either Arens multiplications is a Banach algebra, see [1]. The constructions of the two Arens multiplications in lead us to definition of topological centers for with respect to both Arens multiplications. The topological centers of Banach algebras, module actions and applications of them were introduced and discussed in [3, 5, 6, 9, 15, 16, 17, 18, 19, 24, 25]. In this paper, we extend some problems from [3, 5, 6, 16, 22] to the general criterion on module actions with some applications in group algebras. Baker, Lau and Pym in [3] proved that for Banach algebra with bounded right approximate identity, is an ideal of right annihilators in and . In the following, for a Banach , we study the similar discussion on the module actions and for Banach , we show that

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In this paper, a collocation method based on the Bessel polynomials is used for the solution of nonlinear Fredholm-Volterra-Hammerstein integro-differential equations (FVHIDEs) under mixed condition. This method of estimating the solution, transforms the nonlinear (FVHIDEs) to matrix equations with the help of Bessel polynomials of the first kind and collocation points. The matrix equations correspond to a system of nonlinear algebraic equations with the unknown Bessel coefficients. Present results and comparisons demonstrate that our estimate has good degree of accuracy and this method is more valid and useful than other methods.In this paper, a collocation method based on the Bessel polynomials is used for the solution of nonlinear Fredholm-Volterra-Hammerstein integro-differential equations (FVHIDEs) under mixed condition. This method of estimating the solution, transforms the nonlinear (FVHIDEs) to matrix equations with the help of Bessel polynomials of the first kind and collocation points. The matrix equations correspond to a system of nonlinear algebraic equations with the unknown Bessel coefficients. Present results and comparisons demonstrate that our estimate has good degree of accuracy and this method is more valid and useful than other methods.

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Determining the Optimal Complexity of Bipartite Access Structures

Abbas Cneraghi

Abstract

Keywords: Complexity, Secret Sharing Scheme, Access structure.



In a bipartite secret sharing scheme, the set of participants is divided into two parts, and all participants in each part play an equivalent role. The ideal bipartite access structures were characterized by Padro and Saez, but it is not known which is the optimal information rate of non ideal bipartite access structures. Determining the optimal complexity of general access structures is one of the major problems in secret sharing. We study this open problem restricted to the bipartite access structures, obtaining a new method to compute bounds on the optimal complexity. Namely, by using the connection between secret sharing schemes and polymatroids, we show a linear programming problem that determines, for each access structure, a lower bound on the complexity. Moreover, we show new optimal constructions for certain bipartite access structures.

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In this paper, we study the electronic transport of a multi-molecular chain of copper phthalocyanine connected to two metallic leads by using Green’s function method at the tight-binding approach. The results show that in the gaps of this system, the density of states is independent of the number of molecules or the system length. Moreover, increasing of the system length decreases the tunneling conductance and causes the appearance of peaks and dips in the gaps of the conductance spectra and depending on the value of incoming electron energy, the electron tunneling takes place easier, especially in the edges of the gaps.

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In the present study, we investigate DC conduction mechanism of electron beam evaporated   Bromoaluminium phthalocyanine (BrAlPc) thin films using aluminum and gold electrodes. The current-voltage characteristics of sandwich type device are evaluated for the temperature range 298-413K under dark conditions. It is observed that the current passing through the device is increased by increasing temperature at the same voltage in the range of 0-6v. It is found that at lower voltages about 0 to 2v, the current–voltage characteristics demonstrate Ohmic behavior, while the space charge limited current (SCLC) becomes apparent at higher voltages about 2 to 6v, which is restricted by single discrete trapping level. We obtained more than one linear region in the temperature dependence of electrical conductivity. Also, the values of charge carrier mobility and the activation energy of device are evaluated.

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The concept of rotundity is not far from differentiability . Some paper investigate the relation between rotundity and smoothness. In this paper we will explain some new relation between rotundity and very smoothness.
A Banach space is rotund if the midpoint of every two distinct points of unit sphere is in the open unit ball of Banach space. A Banach space is smooth if its norm is Gateaux differentiable at every non zero point of the space and it is very smooth if the norm is very Gateaux differentiable. That is , the norm of Banach space and the norm of second dual of Banach space are Gateaux differentiable at every non zero point of Banach space.

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In this paper rationalized Haar (RH) functions method is applied to approximate the numerical solution of the fractional Volterra integro-differential equations (FVIDEs). The fractional derivatives are described in Caputo sense. The properties of RH functions are presented, and the operational matrix of the fractional integration together with the product operational matrix are used to reduce the computation of FVIDEs into a system of algebraic equations. By using this technique for solving FVIDEs time and computational are small. Numerical examples are given to demonstrate application of the presented method with RH functions base.In this paper rationalized Haar (RH) functions method is applied to approximate the numerical solution of the fractional Volterra integro-differential equations (FVIDEs). The fractional derivatives are described in Caputo sense. The properties of RH functions are presented, and the operational matrix of the fractional integration together with the product operational matrix are used to reduce the computation of FVIDEs into a system of algebraic equations. By using this technique for solving FVIDEs time and computational are small. Numerical examples are given to demonstrate application of the presented method with RH functions base.

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Genus Cerastium belongs to the subfamily Alsinoideae. This genus is represented with about 30 species in two subgenera (subgenus Dichodon and subgenus Cerastium) and three sections (sect. Strephodon, sect. Orthodon and sect. Schizodon) in flora Iranica area, of which 19 species were reported from Iran. The materials in the TARI herbarium were studied. The vegetative and reproductive characteristics of specimens were checked by stereomicroscope. In family Caryophyllaceae, the seeds bear numerous characters which can be used for taxonomic purposes. The ornamentation features of the seed surface and its relief are different from one species to another. The seeds were carefully taken from mature and dehiscent capsules. Pollen grains obtained from flowers bearing mature anthers. In this paper, Cerastium pentandrum (Caryophyllaceae) is reported as a new record from northwest Iran and Iranian plateau. It belongs to the subg. Cerastium sect. Orthodon. In this section teeth of the capsule are elongated, straight or reflexed, with flat or recurved margins. Morphological characteristics of the new record are provided. This taxon is compared with its closest relative C. balearicum. The ultrastructure of seed and pollen is examined by SEM.

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Today, induced pluripotent cells (iPS) have been recognized as a new and good cell source for cell therapy. In this study, we examined whether human iPS cells, cultured on scaffolds, can differentiate into definitive endodermal cells, as precursor for hepatocytes, pancreatic and lung cells. Embryoid bodies (EBs) composed of iPS cells then EBs were seeded on electrospinning nanofiber scaffold (PCL). The cells were differentiated into definitive endoderm by using IDE1(induced definitive endoderm). Expression of definitive endoderm markers including Sox17, FoxA2 and Gsc were confirmed by Immunocytochemistry attaining and RT-PCR analysis. In the present study, cells morphology and cells viability were evaluated by using a scanning electron microscopy and MTT assay respectively.The results of this study demonstrated the positive effect of 3D cultures, by using suitable factors, on definitive endoderm differentiation.definitive endoderm by using IDE1(induced definitive endoderm). Expression of definitive endoderm markers including Sox17, FoxA2 and Gsc were confirmed by Immunocytochemistry attaining and RT-PCR analysis. In the present study, cells morphology and cells viability were evaluated by using a scanning electron microscopy and MTT assay respectively.The results of this study demonstrated the positive effect of 3D cultures, by using suitable factors, on definitive endoderm differentiation.

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To assess nickel-induced toxicity in plants, Zea mays seeds after germination were cultured on hydroponic nutrient solution with nickel concentrations of 0, 50, 100 and 200 micro molar for a period of two weeks. Then its effect on the growth, Hill reaction and photosynthetic pigment's content were investigated. The fresh and dry weight of leaves and roots increased in 50 &muM nickel but decreased in 100 and 200 &muM. The decline in length of root and shoot were observed by increasing Ni concentration.According to results, root and shoot showed differential growth response to varried concentrations of nickel. Ni concentrations up to 100 &muM caused incrtease in the content of chlorophyll a, but it was decreased at 200 &muM Ni. No significant changes in chlorophyll b and carotinoids content observed. The rate of Hill reaction as an ability of chlorophyll a in the reaction center of PSII680 to split water, decreased by increasing Ni concentration.

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Saponins are secondary metabolites that are found in many plants and some animals. These compounds are high molecular weight glycosides, consisting of a sugar moiety linked to a triterpene or steroid aglycone. Many saponins have detergency properties and give stable foam in water. The genus Silene L. with more than 700 species is one of the largest genera of the family Caryophyllaceae mainly distributed in north hemisphere. Saponins are one of important secondary metabolites in members of the genus. Quantitative and qualitative study of the saponins in the aerial parts and roots of three Silene species, namely S. ginodioca, S. spergulifolia and S. swertiifolia were carried out by spectrophotometry and TLC methods. In this study, 5 fractions were obtained from each plant part and in both parts of three species, fraction 1 contain the highest amounts of saponins. On the other hands, root extracts have a high amount of saponins. In addition, thin layer chromatography (TLC) of the extracts evaluated some saponins spots with different Rf.

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Aliabad Damagh region in southern Hamadan, is located NW of Sanandaj Sirjan Zone. In this region, different metamorphic rocks with a variety of fabric elements are exposed. In this research, metamorphic rocks were investigated based on the microfabric and temperature. In the area deformation occurred along the temperature variations path. Three generations of foliation and four deformation phases are present in the region. Porphyroblasts growth in foliation and microfabric evidence reveal that deformation began during regional metamorphism, while mica and chlorite crystallized as post tectonic minerals compare to S₃ during retrograde metamorphism. The highest grade of this metamorphism is green schist to amphibolite facies.
Deformation elements in granite mylonite and metamorphic rocks in Aliabad Damagh region imply occurrence of regional metamorphism followed by a dynamic metamorphism which cause a widespread ductile shear zone. Deformation elements in carbonate mylonites, confirm the presence of a right lateral shear zone. Based on calcite twinning in mylonitize marbles the temperature of dynamic metamorphism is higher than 200 ˚C. Based on the effect of temperature on lithology, fabric and strain rate, the shear zone in Aliabad Damagh region is ductile to brittle.  

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Garnet-micaschists from Haji Qara high, north of Golpayegan, are part of the metamorphic rocks of the Sanandaj-Sirjan Zone (SSZ). Lepidoporphyroblastic and porphyropoikiloblastic are the main textures and the mineral assemblages consist dominantly of Fe-biotite, muscovite and ferriphengite, metamorphic Fe-Mg chlorites (I-type and IIb), garnet and quartz. Staurolite, andalusite, plagioclase carbon, Fe-oxides and tourmaline are present as accessories. Petrographic evidences as well as mica chemistry along with other paragenesis and thermometric estimations indicate a path change from amphibolites facies to lower pressure and higher temperature gradient suggesting the presence of a local pluton which led to garnet porphyroblast, biotite and muscovite (overprinted in different orientation) and andalusite crystallization. The occurrence of chlorite, ferriphengite and Fe-oxides demonstrate a retrograde metamorphism during uplift and decompressional cooling path in the area.

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Three granitoid bodies, Shirkuh batholith, Kaffe Abad and Ader Bolandan are exposed in NW Yazd, Cutting across the Naiband formation (Upper Triassic), and overlain by Cretaceous formations. Shirkuh batholith is most likely of Jurassic age. It seems to be the first and the most significant episode of magmatism in studied area which occurred in Middle Jurassic (Late Cimmerian) time. On the other hand, contact metamorphism of Cretaceous limestone arround the Kaffe Abad and Ader Bolandan intrusive bodies due to intrusion of granites and dioritic dikes and also the formation of various skarns indicate that the Kaffe Abad and Ader Bolandan intrusive bodies were emplaced during the later orogenic phases. Therefore, Shirkuh granitoid batholith has a wide range of Plutonic activity during Jurassic time, the most important episode of which has occurred in Middle Jurassic. Because of metamorphism of surrounding Cretaceous limestons, the Kaffe Abad and Ader-Bolandan intrusive bodies are at least younger than Lower Cretaceous and it is also possible that they are Oligo Miocene in age. Quartz, plagioclase and orthoclase are the major minerals, while garnet, biotite, pyroxene, amphibole, tourmaline, apatite, zircon, cordierite, andalusite, magnetite and hematite are found as accessory minerals in these rocks. SiO2, Na2O, K2O and CaO content are variable in different parts of the intrusive bodies. Spider diagrams clearly demonstrate Ba, K, Rb enrichment and Ti, Sr, Nb depletion in these rocks. Geochemically, two types of granites, I and S, are recognized, S type granites of which are more abundant in the region. Marble, skarn, Fe Cu Pb Zn. mineralization and non metalic minerals, such as kaolinite exist as economic potentials.