PEYKE NOOR JOURNAL SCIENCE
Year:2008 | Volume:2 | Issue:1|Papers Count:10

Persistent photoconductivity (ppc) has been investigated in detail in a bulk CdTe (Sb) Semiconductor. The relaxation of ppc in CdTe (Sb) is found to follow a power_law, Ippc (t)=t –a, in temperature region 110K< T<295 K, The parameter a as a function of temperature is obtaind.However, the ppc is observed only above 90K, that is contrast to previous reported results on most materials which exhibit PPC effects predominantly at low temperatures. Apossible mechanism is the presence of random local potential fluctuations in the sample, which strongly influence the carrier transport properties. Such fluctuations could be induced either by the compositional fluctuations or the impurity potential.

Vavsar area covers an area of 2413 hectares situated in 53o37'35" -53o43'45" longitude and 36o5'40"-36o10'13" latitude.The vegetation of Vavsar area was studied, using the Braun-Blanquet (Zygmatist) School. Based on the analysis of phytosociological data and by using AFC and CAH methods, 8 associations were recognized.The Following associations constitute the major part of the area: Astragalo caspici-Onobrychidetum cornutae, Stachyetum laxae, Fagetum orientalis, Querco macrantherae-Fagetum orientalis. The distribution of plant associations in the protected areas is mainly affectedby topographic features, including altitude, slop and exposure as well as edaphic factors, such as soil depth and texture.In general, these factors operate in the establishment of plant communities in the different elevation zones and slopes.

Due to high antagonistic activity of Trichoderma viride and Gliocladium virens, isolates T.v.Mo from T.viride and isolates Torbat I and G.v.pro from G. virens were selected and their efficacy was studied on Rhizoctonia solani (caused sugar beet damping-off) in invitro conditions.Antagonistic ability of Trichoderma and Gliocladium isolates was investigated as dual culture on PDA in concomitant and sequential cultures, 48 and 96 hours after R. solani culturing and it was found that all isolates inhibit R. solani mycelial growth. Isolate T.v.Mo in experiment 1 and 2, and isolate Torbat I in all 3 experiments stopped its mycelial growth and sporulated on it. Volatile metabolites of antagonistic isolates had significant inhibitory effect on mycelial growth of the pathogen, among which G.v.pro isolate with inhibition percent of 85.55% had the best effect. In investigation of inhibitory effect of 5 concentrations (10-% 15-% 20-% 25-% 30-%) of culture filtrates of antagonistic isolates in reduction of R. solani mycelial growth, it was found that none of the isolates at the mentioned concentrations had any effect on R. solani mycelial growth. Microscopic observations showedthat these isolates coiled around, penetrated and degenerated hyphae of R. solani, stopped its growth and finally lysed it.

In this paper, using paraformaldehyde and formic acid as reagent in solution phase benzylic oximes with high yields have been converted to the corresponding carbonyl compounds and non benzylic oximes showed no reaction to this reagents. Also, these reactions have been examined in solvent- free conditions which led to the regeneration of carbonyl compounds.

In this work, first, copolymer of butyl acrylate/vinyl acetate (ButAc-co-VAC) was prepared by emulsion polymerization in aqueous medium. In the second step, aniline was polymerized in the copolymer matrix by chemical oxidation polymerization. Polymerization of aniline was carried out in the presece of p-toluene sulfonic acid (PTSA) as do pant.Ammonium per sulfate was used as an initiator. Purified composite material of Polyaniline/ (BuA-VAc) was dissolved in dichlorometane byusing mechanical mixer. The films was prepared by casting method. The four-point conductivity measurements showd that the blend conductivity is 2.8 S. cm-1. Cyclic voltammograms (CV) revealed that the blend materials are electroactive. It was shown that the electrical activity of polyaniline was transfered successfully to the blend. Amount of conductivity compared with various do pant ions. The mechanical properties of the films indicated that the blend could be considered as an elastomer.

One of the most important aims in composite industry is to improve the properties of composite materials. In this research the effects of adding polypropylene Fiber and also the nano silica particles to epoxy resin using hand lay-up technique have been studied. It was found that increasing the polypropylene fiber with lower amount of glass fiber with increasing amount of nano silica up the 0.4 phr improved the impact properties of composites, but these properties showed a decreasing trend when adding over 0.4 phr nano silica. However, the same trend was observed when tensile strength and tensile modulus were determined: In case of bending tests, increasing the amount of polypropylene fiberincreased the bending strength and modulus. But by adding nano silica particles a reverse effect was observed.

The studied area is located in 60km Northwest of Yazd. The area is tectonically situated in Urmya-Dokhtar volcanic belt and central Iran zone. The granitic rocks of this region belong to oligocene-miocene age, and have a composition in range of Syenogranite to Granodiorite.Petrographi studies have shown the various textures such as: granophyric, myrmekitic, antirapakivic and Perthite. Sometimes they have Porphyritic and Cataclacitc antirapakivic and Perthite. Sometimes they have Porphyritic and Cataclacitc texture. According to tectonomagmatic classification, these granites are similar to Cordilleran and active continental margin subduction and emplaced after the collision. Evidences of petrographiy and geochemistry have shown the existence of alkaline metasomatism processes in these rocks.Geochemically, rocks in the area vary in composition from meta to per Aluminus and belongs to high caclo-alkaline potassic Magmatic series and according to the changing of major and trace elements on Harker and Spider diagrams, these graniyic rocks can be assumed as syngenetic volcanic rocks. So central Andean geodynamic model can be suggested for this area. In this model, multi-origin and multu-stage processes supposed to be major in the formation of the magma.

Soaking some of plants on different concentration of IAA from 0-1mg/lit accelerates root formation and increases the number of adventitious roots. Some of woody plants, platanus occidentalis, Malus domestic, Armenia vulgarisdon' t response to these treatments.But some of them response to one of treatments that one of these concentrations is optimum.Monstera deliciosa, Syngonium podophyllum, Nerium oleander, response to these treatments. But no significant difference were between control and other treatments.But inLigustrum vulgare 5×10-1mg/L IAA increases number of roots and fresh and dry weight significantly and inLonicera caprifolium1×10-1 mg/L IAA increases number of roots than control and some treatments.

Industrial and municipal waste water frequently contain metal ions.These metal ions when present in sufficient quantity can be harmful to aquatics life and human health. Current method for such waste water treatment include precipitation, coagulation, flotation, filtration membrane process, electrochemical process, ion exchange process, biological process and chemical reaction. Each method has its merit and limitation in application. Due to high cost of activated carbon, theresearchers have been highlighted the application of lowcost material for metal removal. In this research the ion exchange method for three different metallic ions were experimentally investigated by using the mineral zeolite (clinoptilolite). A pilot of P.V.C. and clinoptilolite bed was designed and construct. The synthetic waste water sample, was prepared that contained the different concentrations of Co2+, Fe2+ and Ni2+ in solution. This solutions was exanimate at different debits where applied on the bed. The result of analysis showed that the clinoptilolite is capable to remove the mentioned heavy metals. The result also shown that the rate of Ni ion removal was slower than Fe and Co ions. The result of analysis of industrial wastewater show that, this type of zeolite, also, can remove the heavy metal ions Fe2+, Ni2+, Cd2+ from these wastewaters. Also, the rate of Ni ion removal in industrial wastewater was slower than that of Fe and Cd ions. This phenomenon was attributed to smaller dimension of Ni ion and its higher electronegativity. The filmy resistance at high debits decrease, by reason of decrease in thickness of static layer.