مجله ایرانی علوم و تکنولوژی-الف
سال:1393 | دوره: | شماره: |تعداد مقالات:12

Some partial action properties of a group G on a C*-algebra A are extended to an action of a unital inverse semigroup S on C0(X). Also, invariant and quotient ideals of C0(X)×aS are considered.

In this work, we apply the radial basis functions for solving the time fractional diffusion-wave equation defined by Caputo sense for (1<a£2). The problem is discretized in the time direction based on finite difference scheme and is continuously approximated by using the radial basis functions in the space direction which achieves the semi-discrete solution. Numerical results show the accuracy and efficiency of the presented method.

The first extended zeroth-order connectivity index of a graph G is defined as 0c1(G)=SvÎV(G) D-1/2v where V(G) is the vertex set of G, and DV is the sum of degrees of neighbors of vertex v in G. We give a sharp lower bound for the first extended zeroth-order connectivity index of trees with given numbers of vertices and pendant vertices, and characterize the extremal trees. We also determine the n -vertex trees with the first three smallest first extended zeroth-order connectivity indices.

Using enrichment procedures, 45 organic solvent-tolerant lipase producer bacterial strains were screened from areas contaminated by oil and organic solvents. Among the strains, 15 isolates exhibited extreme stability toward organic solvents and high lipolytic activity. The NEB-1 isolate which was later identified as Pseudomonas sp. strain NEB-1 by biochemical tests and 16S rDNA gene sequence analysis was selected based on extremely high tolerance to organic solvents and maximum lipase production. Biochemical studies revealed that the crude lipase was stable at temperatures between 20 oC and 60 oC and pH ranges of 4 to 11 for 1 h. Optimum pH and temperature of the enzyme were revealed to be 9.5 and 70 oC, respectively. The crude lipase showed remarkable tolerance in presence of different organic solvents with a broad range of hydrophobicity characteristics. The solvent stable lipase showed an attractive potency for application in biocatalysis in non-aqueous systems and biodiesel production.

The present study is aimed at assessing the ability of Pseudomonas sp. AN29 to uptake Hg2+ from the metal contaminated environment. The minimum inhibitory concentration (MICs) of Hg2+ was 500 mg/ml. Pseudomonas sp. AN29 could tolerate Pb2+ (600 mg/ml), Cu2+ (200 mg/ml), Cd2+ (50 mg/ml), Zn2+ (50 mg/ml), Ni2+ (550 mg/ml) and Cr6+ (150 mg/ml). The isolate showed typical growth curve but phases (lag and log) extended in the presence of mercury. Bacterial isolate showed optimum growth at 37oC and at pH of 8. Metal processing ability of the isolate was determined in a medium containing 100 mg/ml of Hg2+. Pseudomonas sp. AN29 could decrease 85% of mercury from the culture medium after 40 hours and was also able to remove Hg2+ 10%, 40%, 50% and 56% from the growth medium after 8, 16, 24 and 32 hours, respectively. Pseudomonas sp. AN29 was also able to uptake 74% of Hg2+ (pellet) from the medium after 24 hours of incubation at 37oC. Excellent metal uptake ability of Pseudomonas sp. AN29 indicates the possibility of using the bacterial strain for the removal of mercury from metal-contaminated wastewater.

Recently, the strong consistency and asymptotic distribution for the maximum consecutive pairwise likelihood estimators (MCPLE) have been established in the linear time series models. In this paper, the weak convergence of the maximum weighted pairwise likelihood estimator (MWPLE) of the parameters of the AR (1) models is established by using the concept of L2 convergence (convergence in mean square).

For the first time, an unusual assemblage of talc-phengite-chlorite-K-feldspar was found in quartz schists from the Sanandaj-Sirjan zone in the Nahavand area in western Iran. The talc-bearing quartz schists occur as small bodies or lenses within pelitic schist layers and contain talc, phengite, chlorite, K-feldspar and quartz as major mineral constituents with subordinate amounts of calcite and graphite. Textural analysis revealed that talc, phengite, chlorite and K-feldspar are in sharp contact and no reaction rims between them were observed. Constructed petrogenetic gird in the K2O-FeO-MgO-Al2O3-SiO2-H2O (KFMASH) model system containing talc, phengite, chlorite, K-feldspar, phlogopite and kyanite with excess quartz and H2O shows that divariant assemblage of talcphengite-chlorite-K-feldspar is stable over a wide P-T range defined by the following two univariant reactions: phengite+talc+quartz=chlorite+K-feldspar+kyanite+H2O and chlorite+phlogopite+quartz=talc+ phengite+K-feldspar+H2O. Constructed Al2O3-KAlO2-MgO+FeO (AKM) compatibility diagrams predict that phengite (XPh=0.280, YPh=0.860), chlorite (XChl=0.570, YChl=0.640), talc (XTlc=0.160, YTlc=0.02) and Kfeldspar are stable at P=11 kbar and T=400oC. This relatively high-pressure assemblage could be formed during the subduction of the Neo-Tethys oceanic plate under Iranian microcontinent.

Microwave energy has potential for the efficient heating of minerals. Minerals or materials, which couple to microwave energy are called dielectrics and many valuable minerals are found to be dielectric. The mineral ilmenite is one which shows good dielectric heating characteristics. In this paper, the effect of microwave heat energy on the partial reduction of oxidized ilmenite oxidized in a conventional muffle furnace at 900oC for 3 hours is attempted. Carbon as an additive was used for reduction of ilmenite at different time intervals using microwave oven as well as microwave sintering furnace. The results indicate that at one minute, the metallic iron formed contained 0.39% and no observation in mineral phases was observed from microwave oven. At three minutes duration, a partial phase transformation of ilmenite was observed and the metallic iron contained is 1.65%. Interestingly, at six minutes duration a distinct metallic iron phase containing 32% metallic iron is seen in microwave oven. The result of preliminary investigations from microwave sintering furnace indicates that apart from metallic iron phase, the distinct Titania phase was also observed. Further studies are in progress.

Life cycle assessment (LCA) is one of the decision support systems which can be considered for assessing the different approaches of Waste Management. However, it only considers environmental effects and ignores other decision making options such as economic and social effects of solid waste management. In this research, we consider a combination of three decision making options including environmental, economic and social effects to compare current waste management system to six alternative scenarios for selecting the best scenario of solid waste management for Isfahan city where a total of approximately 1000 tons/day of waste is generated. SimaPro7 libraries through Eco-Indictor 99 method were used to obtain background data for the life cycle inventory and assessing mid and end points of environmental impacts. One ton of municipal solid waste of Isfahan was selected as the functional unit. Output of LCA along Economic and social effects were compared with Technique for Order Preference by Similarity to Ideal Solution method. According to Multi-criteria Decision Making, S5 and S1 (recycling, composting and landfilling) were selected as best scenario in terms of lower environmental impacts (human health, ecosystem quality and resources) and finance requirements.

This paper investigates the dynamics and stability properties of a discrete-time Lotka-Volterra type system. We first analyze stability of the fixed points and the existence of local bifurcations. Our analysis shows the presence of rich variety of local bifurcations, namely, stablefixed points; in which population numbers remain constant, periodic cycles; in which population numbers oscillate among afinite number of values; quasi-periodic cycles; which are constraint to stable attractor called invariant closed curve, and chaos, where population numbers change erratically. Our study is based on the numerical continuation method under variation of one and two parameters and computing different bifurcation curves of the system and its iterations. For the all codimension 1 and codimension 2 bifurcation points, we compute the corresponding normal form coefficients to reveal criticality of the corresponding bifurcations as well as to identify different bifurcation curves which emerge around the corresponding bifurcation point. In particular we compute a dense array of resonance Arnol'd tongue corresponding to quasi-periodic invariant circles rooted in weakly resonant Neimark-Sacker associated to multiplier l=e 2pqi with frequency q=2/5 We further perform numerical simulations to characterize qualitatively different dynamical behaviors within each regime of parameter space.

Loess and loess-like deposits cover large areas of Golestan province of Iran, a well-known region in the world for its high incidence rate of esophageal cancer (EC). Despite numerous published works on the possible contributing factors for the observed high incidence rate, very little attention has been given so far to a possible link between the mineralogy of loess deposits in the region and EC incidence rate. This paper tries to investigate in a medical geology context a probable link between the mineralogical composition, grain size distribution, and surface morphology of constituent minerals in loess deposits of Golestan province, and the observed high incidence rate of EC. To achieve this end, loess samples from two districts with high incidence rate of EC, i.e., Dashlibroon and Maravehtappeh were collected, analyzed and compared with the low incidence control area (Gorgan). The results clearly indicate higher quartz and zircon minerals content in Dashlibroon and Maravehtappeh compared with Gorgan control area, revealing a probable link between direct and indirect ingestion of these abrading and lesionforming minerals with EC incidence rate in the area. Gradual decrease of the extent and thickness of loess deposits and resistant heavy minerals content from Maravehtappeh and Dashlibroon towards Gorgan (control area) further confirms the suggested link.

In Statistical quality control a very widely used measure is average run length (ARL) which may be worked out by different methods like integral equation, approximations, and Monte Carlo simulations. The ARL measure and the other related measures are of major significance in every type of production process. An omission in its computation (and hence its related measures such as extra quadratic loss (EQL)) may cause a loss. This necessitates great care in the choice of its evaluation method. This article will deal with this issue using some approximation methods and the Monte Carlo simulations. The discrepancies among the results will be examined to highlight the deficiencies of using approximation methods in quality control techniques.