[en] Short communication

[en] Short communication

[en] Short communication

[en] The notion of a topological quantum mechanical symmetry (topological symmetry, in brief) is introduced. A topological symmetry is a generalization of supersymmetry and involves some topological invariants like Witten index. The algebraic structure of Z₂ graded topological symmetry's of type (m+ , m-) is obtained and it is shown that for topological symmetry's of type (1,1) and (2,1) they are identical to algebraic structure of supersymmetry and p=2 para supersymmetry respectively

[en] The Secondary Standard Dosimetry Laboratories (SSDL s) are the national centers for accurate measurements of X and Gamma radiation, both at therapy and protection levels. In this report, we introduce the Secondary Standard Dosimetry Laboratory of Iran, and then some information regarding the fundamental theories for dosimetry in external radiotherapy is presented. Finally the results of the last annual audits of radiotherapy centers in Iran as well as some quality control considerations in these centers (carried out by SSDL) will be introduced

[en] Since, symbiotic effectiveness is affected by three important factors such as bacteria genotype, plant cultivar and environmental conditions (e.g. soil properties). In this research, simple and interaction effects of the first two factors about symbiosis of three soybean cultivar, which are most commonly cultivated soybean, with several commercial strain of bacteria with three different soils is investigated. For this purpose five Bradyrhizobium japonicum commercial strains (Rhizoking, Helinitro, Goldoat, Biodoz and CB 1809) were taken from soil and water rea search institute. Based on assurance of bacteria strains purity and ineffectiveness with cultivars, for comparison of strains symbiotic effectiveness with soybean cultivars and the best strain selection performed a factorial experiment with RCBD in 24 treatments and 4 replication. The seeds of soybean cultivars were cultivated in Growth chamber under Leonard jar system. The treatment used were 3 levels of soybean cultivar, 5 levels of Bradyrhizobium strains and 3 levels of Nitrogen (0, 35 and 70 PPM). Plants were fed with Brought on and Dil worth solution (1970) for 75 days. Then, plants were harvested and dried. Selective parameters were analysed by MSTATC program. The results indicated that, all bacteria stains were highly effective as far as symbiotic effectiveness is concerned. Eventually Rhizoking, Gold coat and Helinitro stains selected for soybean inoculation. Provided for pot culture, two soil samples from soybean original planting area (in the subregion of Gorgan and Sari cities) and another sample from Karaj countryside were taken with moderate, high and zero symbiont indigenous bacteria levels respectively. For study of interaction and simple effects of Bacteria strain and soybean cultivar in each soil; a factorial experiment with RCBD in 4 replication performed. Factors were contained soybean cultivar (three levels) and three Bacteria strain with a blank treatment for inoculation. In this respect homogenized soil samples were distributed in pots and with consideration of treatment every seed inoculated with 1 ml of special strain inoculum (at Mcfarland's standards no.3). During four months the pots moisture were kept at about Fc 80% with distilled water. Then in reproductive stage 6 (R6) eleven parameters of plant growth in every soil were measured and analysed individually. The results indicated that in Karaj soil considered parameters of Sahar cultivar is higher that other cultivars. In addition all inoculate treatment showed a considerable yield increase in investigated parameters than blank (non inoculated). Results of inoculation with Go and Ri strains were similar but the yield of He strain inoculation was lower. Interaction of cultivar and Bacteria strain was significant too. Calculation of Nitrogen percent (N%) derived from air in this soil for soybean cultivars in symbiosis with Bacteria strains, by using Nitrogen difference method, indicated 80%-9 of plant nitrogen demand were supplied by symbiosis. In Gorgan soil (with intermediate indigenous bacteria level), the soybean cultivar effect on investigated characteristic was signified completely. The best cultivar was Sahar too. The effects of inoculation and also interaction of bacteria strain and soybean cultivar were not significant. In Sari soil (with high indigenous Bacteria level) The cultivar effect (in all measured characteristic) and strain effect (at major of measure characteristic) was significant. Interaction of cultivar and strain on investigated characteristic didn't show to be significant. In this soil, the best bacteria strain for inoculation was Gold coat strain and the best soybean cultivar was Sahar. In general, we can conclude that, in soils without indigenous symbiont bacteria and low nitrogen level, the use of effective and active strain of bacteria inoculum for nitrogen fixing ability and yield enhancement is necessary. In soils with high nitrogen and indigenous bacteria level use of inoculum of strains with high competitiveness and effectiveness can have positive effect on Growth indexes. At last, it is necessary to say that, in application of every kind of bacteria strain as inoculum and also proper plant cultivar for increasing yield, climatic and environmental conditions must be seriously considered

[en] One of the most important natural hazards, that is effective on human life, is earthquake. Iran is one of the seismic zones in the world, so all of facilities and structures should have resistance capability against earthquake. Because of more necessity after earthquake, lifeline have special importance. In this work, seismic investigation of buried concrete pipes, as a part of lifeline, is done. These pipes have diameter more than 1.5 m and joints between pipe segments, have special shapes with special rubber gasket. Pipe segments are modelled as 3-D beams and joint between them are explained by axial and rotational springs. Pipe-soil interaction is expressed as springs and dash-pot in three directions. A nonlinear dynamic analysis of a six segments model is done and the effect of different parameters on pipe-soil interaction, pipe strain and pipe curvature, relative joint displacement and relative joint rotation is studied. The concluded results show that soil incontinuously along the pipeline, incident wave frequency, joint stiffness and soil stiffness are effective parameters in seismic response of pipes

[en] The international wetland of Shadegan with an area of 400 thousands hector is located in south of Khosestan which from south part is connected to Persian Gulf and correlated to it. During the oil-war in Persian Gulf region and discharging crude oil from Kuwait's oil wells into wetland of Shadegan, almost 20% of vegetation coverage in this wetland which is vital for livestock food without any cost, has been extensively damaged. Experts estimated that it takes about 10 years (1370-1380) to recovering the lost of vegetation coverage in this area. Economical evaluation base on effects of oil pollution on vegetation coverage in wetland of Shadegan has been studied by compensation trade upon cost and interest economical Technic. Price of barley as a provender given by governmental agencies to dairy farmers was used as a cost evaluation technic. As a first step, types of vegetation base on cost and quality of nutrient value were classified and then according to these classification, some coefficient for them were determined. By multiplying these coefficients to price of barley (as a dry-provender and best quality) related to year of 1370 until 1379, the money worth (in Rials) of each vegetation community was calculated. For actual economical determination lost of vegetation coverage in wetland of Shadegan it is necessary to multiplying amounts of vegetation lost for each community per year (in hector) to amounts of provender consumed by domestic animals (in ton), which this determines the quantity of vegetation and their types. then by multiplying these quantity to equivalent money worth (in Rials) which is related to amount of vegetation lost per year, will be the actual vegetation lost for each community per year

[en] In this project initially the corrosion behavior of carbon steel was studied in the Bushehr soil, using weight loss and polarization methods. In the next step three types of coatings; P.V.C tape, Polyethylene tape and Coal ar epoxy were applied to cast iron, Rst 37 and 1.4571 steel samples. the thicknesses of the coatings were determined and later resistance to cathodic dis bonding were compared. Also the potential of various holes under coating at backside of sample at different from holiday were evaluated at constant cathodic protection potential of-1380 mv. The results of both polarization and weight loss studies show that the corrosion rate of Rst 37 steel was se creased by exposure time. It was also noticed that the corrosion rate of Rst 37 steel is more than 1.4571 steel. The investigation of cathodic dis bonding tests on coatings indicates that; the maximum resistance to cathodic dis bonding was optioned on 1.4571 steel pipe with PET coating, and the minimum on Rst 37 steel with CT E coating. It was also noticed that with increasing the applied potential and temperature dis bonded area increased in all the cases. Also suggests that an interruption or the removal of cathodic protection from a holiday and along a crevice could ca sue the Ph of the crevice potentials to shift to their more positive rest potential

[en] From the standpoint of processing, hard chromium layer plate may be applied to steels, cast iron, aluminium and nickel base alloys. Cast iron can be plated provided that the surface is capable of conducting the required current and is reasonably free of voids, pits, f ross silicate inclusions, and massive segregations. There are many difficulties arising from graphite phase and deposition of hydrogen on the surface of gray cast iron . To obtain desired hard chromium coating with acceptable adhesion, special pretreatments should be used. In this paper the surfaces of gray cost iron. were prepared in sulphuric acid, chromic acid + SO₄- by anodic etching phosphoric acid + sulphuric acid solution by electropolishing and sulphuric acid + fluoridric solution by dipping in the different conditions. The best results for removal of graphite from the surface of specimens are obtained after anodic etching in 60% H₂SO₄ solution