---

The body chemical composition in aquatic organisms is related to nutrition, habitat, age and sex. On the other hand, knowing the amount of chemical compositions helps to select the appropriate species for human nutrition and food industry. In this study, the change in chemical composition of common carp in different weights was investigated. For this purpose, 25 two-year-old carp were studied during the second year of rearing from different weight groups from 500 g to 1600 g. Protein, fat, ash and dry matter content of fish meat were measured. The results showed that the mean protein content of carp was 10.209 ± 2.106 %, fat was 9.429 ± 0.937%, ash 1.407 ± 198 % and dry matter 21.13 ± 1.62%, respectively. In addition, the results of this study indicate that there is no significant difference between chemical compositions of carp in different weights (P> 0.05). The results of the present study show that there is no relationship between chemical compositions (protein, fat, ash, dry matter) and the weight of common carp and the weight of fish has no effect on the chemical compositions. Therefore, there is no difference in common carp meat chemical compositions in different weights.

---

Aims Hematological and biochemical parameters are valuable indicators for monitoring fish health and physiological responses, nutritional status and environmental conditions affecting fish health. In this study, the comparison of hematological indices and some biochemical and hormonal factors of blood serum in male and female sea carp were investigated.
Materials and Methods For this purpose, blood samples were taken from two groups of male and female broodstock with 14 fish from each group.
Findings The results of this study on hematological factors showed that in terms of  red blood cell (RBC), hematocrit (HCT), hemoglobin (HB), mean red blood cell volume (MCV), mean concentration of hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), white blood cell (WBC), monocyte (Mo) and granulocyte (Gr), there is no statistically significant difference between the two sexes (P> 0.05). The results of this study showed that there was a statistically significant difference between males and females in terms of glucose, cholesterol, calcium and cortisol (P <0.05). The amount of glucose and cholesterol in males and the amount of calcium and cortisol in females were higher. There is no statistically significant difference between males and females in terms of triglyceride, total protein, albumin, sodium and potassium (P> 0.05).
Conclusion The results of this study show that sex in sea carp during maturity has no effect on the hematological parameters of fish but can affect some biochemical factors in the blood serum of carp such as glucose, cholesterol, calcium and cortisol.

---

 Design and optimization of a single crystalline silicon (c-Si) solar cell is performed to achieve the maximum light conversion efficiency. Various parameters such as doping concentration and thicknesses, and geometrical dimension of surface pyramids are studied. The inverted surface pyramid is used to increase the efficiency of the solar cell, and engineered oxide layer is used as the passivation and anti-reflect layer. Semi-analytic modeling of the output parameters of the solar cell, and numerical simulation for the structures are performed for the optimization. Fill factor (FF) of 85.4%, open circuit voltage (V_OC) of 761 mV, short circuit current density (J_SC) of 40.1 mA/cm² and the overall cell efficiency of 26.3% are achieved. The optimization procedure leads to 1.5% efficiency increase in compare with the similar works.