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Toxicity and LC₅₀ 96-h of Malathion on the Caspian common carp fingerlings, Cyprinuscarpio, and its effects on some blood indices, including hematocrit, glucose, cholesterol and total protein content, were investigated. The median lethal concentration, the lowest effective concentration and the maximum allowable concentration were found to be 1.3, 0.646 and 0.13 mg.L^-1, respectively. Based on the LC₅₀ finding, Malathion can be regarded as “moderately toxic” for this fish.  Significant differences between the hematocrit, glucose, and cholesterol among treatments were evident, but no significant difference in the total protein of blood plasma was observed. The hematocrit level in the control group was lower than the other groups. The lowest levels of cholesterol and glucose were observed in 0.5 mg/L, and the maximum levels were found in 2.5 and 2 mg/L, respectively. Therefore, malathion which is supposed to be ineffective for non-target species at allowable concentrations, can lead to their blood indicies responses and bio-damages.

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Aims: The present study intends to assess the toxicity of CuO and ZnO nanoparticles (NPs) at laboratory conditions on some pathogenic bacteria for the reared fish, as well as, a bioassay on rainbow trout.
Material & Methods: For this purpose, the sensitivity of them to the mentioned NPs with a reference antibiotic (florfenicol) was assayed through the well diffusion method, as well as, minimum inhibitory concentration (MIC) and minimum bacteriocidal concentration (MBC) were determined by microdilution technique. On the other hand, the lethal toxicity test has been accomplished to the calculation of median lethal concentration (LC50) on some rainbow trout (55.3±7.6 g) in static condition for the 96 consecutive hours. We use one-way ANOVA and Probit regression in order to data analysis.
Findings: Results show that NPs of copper oxide and zinc oxide could significantly inhibit the growth of Streptococcus iniae or kill it at 0.18 and 0.24 µg/ml and more, respectively. The comparison between LC50-96h quantities of CuO NP (107.4 µg/l) and ZnO NP (102.3 µg/l) indicated that the CuO NP has more toxic potential.
Conclusion: According to the laboratory findings, the susceptibility of S. iniae and L. garvieae to ZnO NP were close to florfenicol. The mortality in the fish species due to lethal toxicity would occur if the effective concentration of NPs on the bacterial pathogenic agents being used directly.

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The present study intends to assess the effects of Na diformate oral use with citric acid on some skin mucosal immunity indices (total protein, total immunoglobulin (TIg), lysozyme, protease, esterase, and alkaline phosphatase (ALP)) of rainbow trout following experimental challenge with Yersiniosis agent (Yersinia ruckeri). Subsequent to the determination of the 7-day median lethal dose (LD50) of Yersinia ruckeri, fish were stocked in eight groups and two repetitions. The acidifiers separately with a dose of 0.2%, and combined 0.1+0.1% was added to the commercial diet. Five days after inoculation, feeding of fish with acidifiers commenced, and following 15 days, the mucus samples were gathered from the skin of anesthetized fish to measure immune indices. Results showed that the 7-day LD50 of Y. ruckeri was 8.91×105 CFU/ml. In the main experiment, findings indicated the significant effect of Na diformate on the increased levels of mucoid total protein and proteolytic activity of healthy or diseased fish. The acidifiers-contained diet because of potentially having synergistic effect caused inducing the mucus TIg. It seems that the orally use of Na difirmate in 0.2% of the diet separately or combined with citric acid, at least for 15 days, can improve the cutaneous mucus immunological indices that its result is an increase in the survival rate of farmed rainbow trout.

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The electrohydraulic valves are commonly used in the engineering applications. These valves, as the medium elements, prepare the hydraulic systems for the electrical control applications. For the precise performance of these valves, disturbances in the valve elements dynamics will disturb the control process of the system. The electrohydraulic servo valves are greatly affected by the external acceleration, for instance in the aerospace applications. In a two stage flapper- nozzle electrohydraulic valve, the external acceleration changes the pressure of the fluid leaving the nozzles and it affects the flapper and spool of the valve like a virtual force. Thus, when the applied current is zero, the acceleration diverts the spool of the valve from the equilibrium point, and unwanted performance in the valve occurs. In this study the pilot pressures of the spool is modeled in unsteady state condition. The effects of the acceleration on the flapper and the spool of the two stage electrohydraulic valve are investigated. At the end, the obtained model is verified by use of the experimental data.