Showing 8 results for علیشاهی
Volume 9, Issue 3 (Summer 2018)
Abstract
Aims: The bio-toxicity of silver nanoparticles (AgNPs) in the aquatic ecosystem and the detection of lethal concentrations of this material are of importance. The aim of this study was in vivo comparative toxicity of silver nanoparticles and bio-productivity in zebrafish (Danio rerio) in embryo and adult stages.
Materials and Methods: The present experimental study was carried out on 30 fertilized eggs and 30 adult zebrafish and the effects of chemical and bio-productivity of AgNPs were evaluated by brown seaweed (Sargassum boveanum) in evolutionary stages of the embryo and adult zebrafish with a control group and in incremental concentrations. The mortality rate was recorded at 24, 48, 72, and 96 hours after exposure and the data were analyzed by EPA Probit Analysis 1.5 and SPSS 19 softwares, using one-way analysis of variance and Duncan's multiple range test.
Findings: The toxicity of both types of AgNPs in both evolutionary stages was increased with increasing concentrations and time (p<0.05). After 96 hours, the lethal concentration 50 (LC50) in adult fish was 0.788mg/l for chemical AgNPs and 0.409mg/l for bio-produced AgNPs. Mortality rate at the highest concentration (3mg/l) of AgNPs at 72 and 96 hours in all groups was 100%.
Conclusion: Comparison of the toxicity result showed that the biosynthesis form of AgNPs is more toxic potential than chemical form of AgNPs. It seems the sensitivity of embryo stage to both of silver nanoparticles more than to mature stage.
Volume 9, Issue 4 (Fall 2018)
Abstract
Aims: In nanoecotoxicology science, fish erythrocyte micronucleus assay for the monitoring genotoxic potential of nanoparticles is a powerful biomarker. This study was conducted with the aim of investigating genotoxicity of magnetic iron oxide (Fe3O4) nanoparticles in red blood cells of common carp (Cyprinus carpio) using micronucleus assay under acute and chronic treatment. Materials and Methods: In the current experimental study, the genotoxit toxicology of Fe3O4 nanoparticles was performed during an acute (96 hours; 5 concentrations including 0, 10, 100, 500, and 1000 mg/l) and chronic (14 days; 3 concentrations including 0, 100, and 500 mg/l) of Fe3O4 nanoparticles in three replications. The data were analyzed by IBM SPSS 19, using two-way ANOVA, and Duncan's new multiple range test.
Findings: Acute exposure to Fe3O4 nanoparticles had no acute toxicity effect juvenile carp (C. carpio). By increasing the concentration of nanoparticles in a 96-hour interval, the frequency of micronucleus (‰) and other abnormal forms around the red blood cell nucleus of juvenile carps showed a significant increase compared to the control group (p<0.05). In the chronic treatment at concentrations of 100 and 500 mg/l of Fe3O4 nanoparticles, the rate of increase in the frequency of micronucleus was similar to the acute functional test of concentration.
Conclusion: Although Fe3O4 nanoparticles do not have acute toxicity effects in common carp and are non-toxic, they tend to induce genotoxic effects by increasing the frequency of micronucleus and other abnormalities of the red blood cell core during a concentration-dependent process. So, it seems that the release of FeO4NPs into the environment, it is probable adverse effects on aquatic ecosystems.
Volume 12, Issue 2 (4-2023)
Abstract
Chitosan (Cs) was extracted from shrimp shell and its derivative forms including N-alkyl (AlkCs) and nanoparticles (CsNPs) were prepared. First, the properties of nanoparticles were determined by dynamic light scattering (DLS) and the morphology of nanoparticles and N-alkylated by scanning electron microscopy (SEM). Then their antibacterial activity was evaluated by the test of minimum inhibitory (MIC) and lethal (MBC) concentration, diffusion on agar by disk, permeability of cell membrane by measurement of cytoplasmic beta-galactosidase release (ONPG). The type of apoptosis cell death was also examined by DAPI staining and changes in cell surface integrity by atomic force microscopy (AFM). The results showed that the nanoparticles are spherical with an average hydrodynamic diameter of 240 nm. N-alkyl had a rough surface structure compared to native chitosan. At the least of MIC (78 μg/ml) and MBC (100 μg/ml) points were observed for CsNPs (P < 0.05). Nanoparticles and N-alkyl of chitosan showed the highest diameter of growth inhibition zone at 1250 concentration compared to other disks (p <0.05). Outer membrane permeability of derivative forms of chitosan showed significant differences with native chitosan and cells of control. DAPI staining test showed higher cell death of chitosan-derived forms. DAPI staining test showed higher cell death of derivative of chitosan. The images obtained from AFM showed a change in the membrane integrity of the treated cells compared to spherical and clustered of control cells. Thus, the antibacterial properties of native chitosan improved by physical and chemical modification.
Volume 14, Issue 7 (10-2014)
Abstract
In this paper, control and guidance system of a spinning flight vehicle with a single plane of dithering canard control fins are investigated. Decreasing the number of actuators, lowering the vehicle weight, and reducing the final cost are outcomes of applying two canard controls; however, the control system will become complicated due to guidance system interaction. Producing asymmetric force and torque in yaw direction is the result of this interaction. Dithering canard is proposed for proper control of this spinning vehicle. Dithering canard adjusts its deflection with respect to the roll attitude of the flight vehicle. In this paper, a method is proposed for control and guidance of this spinning vehicle with dithering canard. This method is investigated in a six DOF flight simulation in presence of IR seeker, autopilot, gyro, actuators. Appropriate simulation results in various flight situations verify the proper performance of this new control method.
Volume 15, Issue 13 (Special Issue 2016)
Abstract
Volume 15, Issue 13 (Special Issue 2016)
Abstract
Volume 16, Issue 91 (September 2019)
Abstract
Celiac disease is an autoimmune disorder in which the patient is permanently exposed to gluten intolerance during their life. The only effective method for celiac disease is strict adherence to a gluten-free diet. So, attention to the high quality food production without gluten is important. The aim of this study is to produce gluten-free bread toast using Nigella sativa Linnconcentrate as an alternative to gluten and potato fiber. The Response Surface Method was used with two variables of potato fiber (2 to 6 %) and Nigella sativa Linnconcentrate (5 to 15 %). With increasing potato fiber and Nigella sativa Linnconcentrate, bread density increased significantly (p˂0.05). Potato fiber resulted in a significant decrease in porosity, but Nigella sativa Linnconcentrate was ineffective (0.01%). Potato fiber and Nigella sativa Linnconcentrate showed a linear effect alone at the level of 0.05. Moisture content decreased with increasing fiber and Nigella sativa Linnconcentrate, but the effect of protein concentrate was not significant (p˃0.05). In addition, moisture content of bread decreased during storage. Potato fiber and protein concentrate had a significant effect on the hardness of bread texture and the texture increased during the four days storage period. The non-fit index for all models was not significant (0.05%). The optimization of bread formulation showed that the toast containing 7.5% of Nigella sativa Linnconcentrate and 2.5% potato fiber had the best quality and is recommended for production.
Volume 17, Issue 12 (2-2018)
Abstract
The intermetallic compound of gamma titanium aluminide is a kind of recently developed material which has outstanding potential for utilization in high temperature structural applications due to higher ratios of strength to density and also elasticity modulus to density. In this study with considering two dielectric fluids of kerosene and de-ionized water, the effects of the most important input parameters of electrical discharge machining including pulse current and pulse on time on the output characteristics of material removal rate, tool wear ratio, some surface integrity criteria such as surface roughness and cracks, are investigated. The results indicate that, rough machining of titanium aluminide in contrary to finishing of this material, is performed efficiently. As the result of more thermal conductivity coefficient of water comparing with kerosene, the energy dissipation or loss and also plasma channel radius expansion in water is noticeably more than kerosene. This issue leads to more concentration and higher rates of thermal energy on the machined surface in the case of kerosene. Consequently, the density of surface cracks, surface roughness and intensity of surface topography alterations for the machined surface in kerosene is more than the samples which are machined in de-ionized water, but in contrary, the material removal rate with kerosene is much more than MRR in de-ionized water and also the tool wear ratio during machining process by means of kerosene is significantly less than the de-ionized water.
