g. h. rahimi

Earthworms are soil organisms commonly used in environmental studies and biological toxicology. Therefore, the present study aimed to investigate the role of Eisenia Fetida  earthworms on the bioavailability of zinc and copper in the  contaminated soils. This study was carried out on a contaminated soil sampled from the Ahangaran mine 26 kilometers far from the city of Malair and its surrounding areas. In this experiment, 12 earthworms with  the average weight of 0.3 -0.6  g were selected for each soil sample. The worms were exposed to a  metal contaminated soil for 42 days. After the test time, Zinc (Zn) and Cupper (Cu) concentrations were measured in different fractions of the soil. The results showed that cow manure, carrot pulp and vermicompost significantly reduced (at the level of 5%) 62.2, 80 and 65.2 mg / kg of the metal zinc concentration in carbonate, respectively,  as compared to the treatment control. Earthworms significantly increased zinc (81.45 mg kg) in the  carbonate fraction. On the other hand, there was a significant increase in the amount of exchangeable copper with the addition of organic fertilizer to  worm, as compared to the control sample. This increase  was significant (at the level of 1%) in the treatment of Vermicompost (1.27 mg / kg) and carrot pulp (1.32 mg / kg), as compared to control.

Currently, composite structures have many applications in various industries including aerospace, automotive, marine, and petrochemicals. In most of these applications, the structure is under dynamic and static loads and it can cause buckling, vibration, and fatigue. Therefore, the static and dynamic analysis of these structures is essential in order to understand their characteristics, including buckling, natural frequency, and the shape of vibrating modes. One of the most important non-destructive methods for predicting the buckling load of the structure is the vibrational correlation technique (VCT), which is based on frequency variations with the axial load. In this study, an experimental study of the buckling load of composite sandwich plates with lozenge core has been investigated. The hand lay-up method has been used for fabrication of the composite sandwich plates. One of the specimens was used for the modal test. In order to verify the results of the VCT, the buckling load of four specimens was calculated by the experimental buckling test. The error of VCT was 2.1 %. Hence, the efficiency of the VCT for composite sandwich plates with lattice core was confirmed. Also, by investigating the effect of applied load percentage on the accuracy of the VCT, it was found that for the applied load of more than 63% of the buckling load, the accuracy of prediction of the vibrational correlation technique is acceptable.

In the following paper, free vibration analysis of two directional FGM circular nano-plate on the elastic medium is investigated. The elastic modulus of plate varies in both radial and thickness directions. Eringen’s theory was employed to the analysis of circular nano-plate with variation in material properties. Simultaneous variations of the material properties in the radial and transverse directions are described by a general function. Ritz functions were utilized to obtain the frequency equations for simply supported and clamped boundary. Differential transform method also used to develop a semi-analytical solution the size-dependent natural frequencies of non-homogenous nano-plates. Both methods reported good results. The validity of solutions was performed by comparing present results with themselves and those of the literature for both classical plate and nano-plate. Effect of non-homogeneity on the nonlocal parameter, geometries, boundary conditions and elastic foundation parameters is examined the paper treats some interesting problems, for the first time.

Due to unique properties, grid stiffened composite cylinder shells are used extensively in aviation, marine and automotive industry. In recent decades, several studies are done to predict the critical buckling load of grid stiffened composite cylinder shells without breakdown or failure. Vibration Correlation Technique (VCT) is one of the most important non-destructive methods that based on nonlinear vibration analysis. The aim of this research is the prediction of the critical buckling load of stiffened composite cylinder shells with lozenge grid by using VCT. For this purpose, linear and nonlinear vibration analysis of composite cylindrical shells were performed in different compressive loads by using finite element software ABAQUS, firstly. In the next step, linear buckling critical load was determined by using numerical methods. Then, non-linear critical buckling load of grid stiffened composite cylinder shells was predicted by using VCT. To validate the results of VCT, five composite cylindrical shells were fabricated by using filament winding method with same conditions and was placed under axial compression test. Finally, the critical buckling load was measured experimentally. The results show that the difference between the critical buckling load of VCT with experimental buckling load is less than 3%. This subject implies that VCT is suitable for prediction of critical buckling load of stiffened composite cylinder shells with lozenge grid with very high accuracy.

One of the most important issues in genomic selection is using a decent method for estimating marker effects and genomic evaluation. Recently, machine learning algorithms which are members of non-parametric and non-linear methods have been extended to genomic evaluation. One of these methods is Random Forest (RF) on which this research was focused. Important parameters in RF algorithm are the number of SNPs selected randomly at each tree node (mtry), the number of trees to grow` (ntree) and the minimum size of terminal nodes of trees (node size) which need to be pre-defined before analyses and for them the model should be tuned. A genome comprised of five chromosomes, one Morgan each, on which 10000 bi-allelic SNP were arrayed was simulated and the efficiency of different combinations of mtry, ntree and node size was tested and the best combination was selected based on comparison of accuracy of predicted genomic value as well as OOB error estimates. For the simulated data in the current study the least OOB error as well as the maximum prediction accuracy was related to a model with 6000 mtry, 1000 ntree and 5 node size. Other combinations did not increase the accuracy of prediction while led to an increase in time of analyses for those which used more trees. Since the accuracy of prediction is a function of mtry, ntree and node size, in genomic evaluation, different combinations of these parameters should be used and the combination which caused the maximum prediction accuracy should be used for genomic evaluation.

Environmental pollution with heavy metals and their transfer to plants is an increasing universal problem. In this study، raw and treated wastewaters were reused for potato cultivation under lysimetric condition. Consequently، a completely randomized test was designed، with four irrigation treatments and three replications. The irrigation treatments were categorized as follows: irrigation with raw wastewater (T1)، treated wastewater (T2)، a combination of 50% raw wastewater and 50% fresh water (T3)، and a combination of 50% treated wastewater and 50% fresh water (T4). The soil of each treatment was sampled in order to assess the Cd، Zn، Cu and Pb pollutions on the basis of the Pollution Index (PI) and to analyze the correlation between the mentioned metals in two soil depths. The results showed that the effects of irrigation treatments on PI of Cd، Pb (p ≤0. 05)، Zn and Cu (p ≤0. 01) amounts were significant. The maximum and minimum values of this index were observed in the T1 and T4 treatments، respectively. The ranking of PI magnitude in all treatments was T1> T3> T2> T4. Also، the results showed that the PI values of the mentioned metals except Cu in the soil depth of 0-10 cm was lower than those in the soil depth of 10-20 cm. The maximum Pearson’s correlation coefficient value was observed between Pb and Cu. Also، the values of this coefficient in soil depth of 0-10 cm were more than those in the depth of 10-20 cm (except the values between Pb and Zn and between Cu and Cd). In this study، the PI values of Pb، Zn and Cu، were lower than 1 and the PI values of Cd were between 2 and 3.

In this study, the reinforcing effect of organically modified layered clay in two epoxy matrices, TETA-cured and F205-cured, was studied. The epoxy resin system is made of a diglycidyl ether of bisphenol A, Epon 828, as the epoxy prepolymer and the two hardeners were Epikure 3234, namely TETA, and Epikure F205. The organically modified clay, Closite 30B, is dispersed into the epoxy system in a 0%, 1.5%, 3% and 5% ratio in weight with respect to the matrix. The state of dispersion was characterized by X-ray diffraction method. In both systems of epoxy resin, the results of XRD show that the clay has been further intercalated by the epoxy matrix. The tensile and flexural properties of the epoxy/clay nanocomposites were investigated according to the standard tests. The results of mechanical tests indicate that the mechanical behavior of two epoxy resin systems reinforced with clay nanoparticles, are different from each other, so that adding clay into the epoxy matrices makes the TETA-cured nanocomposites more brittle and the others cured with F205 more soften. By comparing the results of two epoxy resin systems reinforced with clay nanoparticles, it is concluded that positive effect of presence of the clay nanoparticles is evident on the mechanical properties of the F205-cured epoxy resin.

Stress and its effect is a significant problem in all organizations; therefore employees and even human are living with it in recent decade. The purpose of present study was to investigate and rank stressor factors on employees’ job performance in Urmia University of Medical Sciences. To simplify and analyze the proposal، we classified stressor factors into 3 groups; personal، occupational and organizational. Personal factors included gender، lack of social support، lack of sense of control and type A personality. Occupational factors involved role overload and under load، role conflict، role ambiguity and organizational factors consist of lack of job security، payroll policies، technology and changing workplace. The results indicated that occupational، personal and organizational stressor factors have had significant effect on job performance respectively. With regard to the personal factors، over the 90% of respondents had sense of control and social support، 23% of them had type A personality and in terms of gender، women job performance was higher than men. Referring to occupational factors، 18% of respondents had role conflict and role ambiguity، 26% of them had role overload and 40% of them have been faced with role underload. Finally، considering to organizational factors، 75% of respondents had job security، 94% of them had compatible sense with job technology، 59% had satisfied with payroll policies and only 23% of respondents had been faced with changing workplace. These results show that the above mentioned stressor factors had positive effect on employees’ job performance and they were free from stress. We suggest that future scholars focus on other stressor factors that have not been investigated in this research.

In this paper, an experimental and numerical investigation into the effect of the hoop welding in metallic pressure vessel is presented. In the experimental manufacturing, hoop welding was used to attach the cylindrical body of the vessel, and the effect of welding into stress and strain distribution is carried out. Experimental strains are obtained by using the strain gauges attached to predetermined places and stresses calculated by using Hook’s law in composite materials. The results of the two methods are compared with each other.

Color is considered as a key element in fields such as painting and architecture. In Iranian poetry color is also of high importance. Having wide range of artistic words and also high poetic talent the poet depicts wonderful and imaginative pictures and decorates them with colorful elements of nature. Old age and Youth are examples of concepts which have been the focus of many poets’ attention and Nezami in particular. These concepts have been beautifully depicted in Nezami’s poems through the color element. The poet has beautifully depicted the young and old generation’s appearance characteristics using his poetic talent and colorful elements of nature. On one hand, white, black and red are examples of the colors used to describe young generation directly or indirectly. On the other hand, old age is described with respect to yellow and white colors. Nezami’s description of youth and old age is well elaborated in this research with aims at analyzing these concepts with regard to the element of color.

Exact methods for major gene detection have been based on using molecular information. Special mating designs with high costing are needed for production of this type information that, without basic research for optimization of production and using them, it would be very challenging and difficult for developing country such as Iran. So, before applying these methods it would be better to, by using statistical methods, segregation of these genes is detected. Some of detected major genes that are using in developed countries animal breeding programs were detected firstly by statistical methods. In this research, using statistical methods, major genes that affecting four economically important recorded traits in two breeding centers, including age at first laying, body weight, egg weight and number of laid eggs, were detected. With deleting outlier and Box-Cox transformation on adjusted data, false positive results were controlled. Normality test on adjusted records of four traits in two centers confirmed that major genes are segregating for these traits. Bartlett test for homogeneity of variance in paternal half-sib families indicated that these variances were not homogeny and χ2 statistics were significant (P<0.01) for all traits. Fain test also confirmed the curvilinear relationship between means and variances of half-sib families and both of these two methods detected segregation of major genes for recorded traits. Mixture test as the most powerful method among all statistical methods for major gene detection in animal population, detected that the best distribution for most of traits is mixed distribution and this is due to of major gene segregation that affecting these traits and different means of major gene locus's genotypes.

In order to detect genetic variation of native fowls in Mazandaran native Fowls breeding station, blood samples were collected from 100 male and female of birds (1:11). The DNA of the blood samples was extracted according to an optimized salting out protocol. The extracted DNA was amplified through polymerase chain reaction (PCR). Of the twenty random primers (10 mer) were used in this study, fourteen yielded satisfactory PCR. The total 63 polymorphic and 77 monomorphic bands were detected for the 14 primers. The number of bands displayed for each primer ranged from 4 to 16 with 200-2100 base pairs. The highest and lowest percentages of polymorphism band were observed for primer 9 (72%) and primer 14 (16%) respectively. The band sharing frequency was calculated for each primer, which ranged from 79 to 96. The genetic similarity within population and genetic variation were estimated as 89 and 11 percentage respectively. In conclusion, the existence of high level of polymorphism after ten generation of selection may indicate the accuracy of genetic evaluation program, suitable selection strategies and also large enough effective population size in this breeding flock.