Iranian Journal of science and Technology (A: Siences)
Volume:36 Issue: 2, Spring 2012

In this paper, we introduce a considerable machinery which permits us to characterize a number of special (fuzzy) subsets in AG -groupoids. Generalizing the concepts of (,q) -fuzzy bi-ideals (interior ideal), we define (,) k q -fuzzy bi-ideals, (,) -fuzzy left (right)-ideals and (,) k q -fuzzy interior ideals in AG -groupoids and discuss some fundamental aspects of these ideals in AG -groupoids. We further define (,) k q -fuzzy bi-ideals and (,) k q -fuzzy interior ideals and give some of their basic properties in AG -groupoids. In the last section, we define lower/upper parts of (,) k q -fuzzy left (resp. right) ideals and investigate some characterizations of regular and intera-regular AG -groupoids in terms of the lower parts of (,) kq -fuzzy left (resp. right) ideals and (,) kq -fuzzy bi-ideal of AG -groupoids.

A method has been presented for finding the solution surface of the NPDE: u  c, bounded by a general space curve. The method is based on the geometric characteristics of the surface, and is called the “Cone-Slot Method”. It has been shown that such a surface can be obtained by movement of a cone inside the slot formed by the boundary space curve. An algorithm has been suggested on the basis of mathematics of these considerations. In previous methods the boundary curve had to be level. They obtain the surface as an assembly of its contour curves. In this method however, the solution surface is obtained as an assembly of its characteristics. The boundary curve can also be a general unlevel skew space curve. The method requires no mesh for calculation and allows the area of the integral surface and underneath volume to be readily determined.

Maji et al. introduced the concept of fuzzy soft sets as a generalization of the standard soft sets and presented an application of fuzzy soft sets in a decision making problem. In this paper, we apply fuzzy soft sets to  - hyperrings. The concept of (, q) -fuzzy soft  -hyperideals of  -hyperrings is first introduced. Some new characterizations are investigated. In particular, a kind of new  -hyperrings by congruence relations is obtained.

In this paper, the use of weighted pairwise likelihood instead of the full likelihood in estimating the parameters of the multivariate AR(1) is investigated. A closed formula for typical elements of the Godambe information (sandwich information) is presented. Some efficiency calculations are also given to discuss the feasibility and computational advantages of the weighted pairwise likelihood approach relative to the full likelihood approach.

In this paper, we introduce a new type of almost statistical convergence of generalized difference sequences of fuzzy numbers. We give the relations between the strongly almost Cesàro type convergence and almost statistical convergence in these spaces. Furthermore, we study some of their properties like completeness, solidity, symmetricity etc. We also give some inclusion relations related to these classes.

In the present work we use the negativity to study the effect of Rashba parameter on the thermal entanglement of electronic spin and subband states inside a quasi-one-dimensional Rashba nanowire, in a perpendicular uniform magnetic field. We assume that the nanowire is held at a temperature T, so that both spin and subband states, with definite probabilities, are present. The partially transposed density matrix is shown to be block diagonal, whose eigenvalues are readily obtained. By analyzing these eigenvalues, it is shown that, even at high temperatures there always exist negative eigenvalues, so that the system of electronic spin and subbands inside a Rashba nanowire is never separable. Moreover, we show that the negativity, at certain temperatures, exhibits maxima. The temperatures at which the entanglement is maximal strongly depend upon the Rashba parameter. We further present graphs of negativity as functions of temperature for different Rashba parameters, showing that the maximal entanglement occurs at lower temperatures for larger Rashba parameters. The novel results in the present article shows how the behavior of spin-subband thermal entanglement depends upon an externally controllable agent.

The chemical speciation of heavy metals (arsenic, chromium, copper, lead, zinc and tin) in the sediments of former tin mining catchment Bestari Jaya, Peninsular Malaysia was determined by using the latest version of the Community Bureau of Reference, usually called the BCR 3-step sequential extraction procedure. Furthermore, a fourth step was introduced for digestion and analysis of the residue. The analysis of total metal content was carried out by using microwave acid digestion. The percentage of each metal obtained from the 4 step extraction (acidsoluble + reducible + oxidizable + residual) is in good agreement with the percentage of total metal content obtained from microwave digestion, which implies the accuracy of the procedure. The degree of pollution in catchment sediments was assessed using geoaccumulation index Igeo and pollution intensity IPOLL. The results indicate that (1) the sediments have been polluted with arsenic (8.8%), chromium (12.9%), copper 17.4%), lead (19.5%), zinc (14.9%) and tin (33.8%) and have high anthropogenic influences; (2) the calculation of geoaccumulation index suggests that catchment sediments have the background concentration for all studied metals (Igeo < 0); (3) High IPOLL showed that all of these heavy metals pose high environmental risk. (4) the mobility order of metals in sediments at S1 and S2 was Sn>Pb>Zn>Cr >Cu >As, whereas at S3, S4 and S5, Cu>Pb>Zn>Cr>Sn>As; In conclusion, acidic pH, total organic carbon, scavenging ability and co precipitation (inclusion, occlusion and adsorption) of studied metals with non-metals could account for change in the geochemistry of the catchment sediments.

A total of 48 female spirlins Alburnoides sp. from the Kesselian stream (South Caspian Sea basin, northern Iran) were examined during a period from July 2008 to June 2009 to obtain data on fecundity, and to determine the spawning season of this carp. The mean absolute fecundity of females spirlin was 1722.92 (653.88) eggs. The fecundity has positive correlation with the size of the female. The mean of the monthly GSI index and ova diameters shows that spirlin spawn once in a year during the months of June-July. GSI of 6.88 was considered as the indicator of sexual maturity for the females. The highest peak of relative condition factor (Kn) was 0.126 during the month of June. The stages of gonads maturation of Caspian spirlin have been classified as: I, immature; II, early developing; III, late developing; IV, mature; V, ripe (spawning)

Oxidative coupling of methane has been studied over (Mn+A+W)/SiO2 catalysts in a continuous–flow micro reactor, where A represents an alkali ion of Li, Na, K or Cs having different weight percents. The main aim of this study is to find the role of alkali ions in interaction between Mn and W species with SiO2 to make a proper structure for catalyzing oxidative coupling of methane (OCM) reaction. The catalysts were characterized by XRD, SEM, FTIR, TPR and also the electrical conductivity was measured in air and under OCM reaction. It was found that for the formation of crystallized catalyst, the amount of alkali ion should be such that the catalyst containing tungsten transforms into A2WO4. Using a smaller amount of alkali ions does not result in crystalline catalyst by calcination under the same condition of temperature and atmosphere. However, under the OCM reaction condition the catalyst gradually turns into a crystalline structure and its catalytic performance, i.e. conversion and selectivity, for the OCM reaction is almost similar to the (Mn+A2WO4)/SiO2 catalyst. The transformation of the catalyst containing alkali ions from amorphous to crystalline one indicates a kind of structural flexibility of the catalyst under OCM atmosphere. The structural flexibility of the catalyst under the OCM reaction is considered to be the main chemical role of the alkali ions.

Plants are potent biochemists; biologically active compounds present in the medicinal plants have always been of great interest to scientists working in this field. Thus, the aim of the current study was to screen the antimicrobial activity of Acacia nilotica, Ziziphus mauritiana, Bauhinia variegate and Lantana camara against some selected clinical isolated strains. Although previous studies have documented the antimicrobial properties of these plants, this work is designed to evaluate the specific antibacterial activity of different extracts of these plants against tested microorganisms, in order to know the best extract against specific microorganisms. In this study the fresh parts (leaves, barks & pods) of the test medicinal plant were collected and methanol, ethanol and ethyl acetate extracts were prepared. Antibacterial susceptibility test was done by using Agar diffusion assay method. Statistical analysis was carried out with SPSS 17.0 Windows version. The results of the current study showed that a total of 8 extracts from 4 different plant species were investigated including pods of ethyl acetate extracts of Lantana camara, which showed the highest antimicrobial activity against tested clinical isolates (Bacillus subtilus 2±0.1mm, Bacillus circulans 2.6±0.2mm, Bacillus sphaericius 2±0.1mm, Staphylococcus aureus 2.5±. , and Serratia liquefaciens 2.2±0.1mm), followed by its ethyl acetate extracts of leaves. Bark extracts of four testedmedicinal plants possess a lower zone on inhibitory activity as compared to the leaves extracts of these plants. Noticeably no antimicrobial activity was found in the methonolic bark extract of Acacia nilotica against the tested bacteria except Bacillu ciurlans. The results of the present investigation clearly indicate that the antibacterial activity varies with the species of the plants and plant material used. Thus, the study ascertains the value of plants used in ayurveda, which could be of considerable interest to the development of new drugs. Studies are in progress to further evaluate the mechanisms of action of these active test extracts on study organisms associated with certain human diseases.