The current study aimed to optimize artificial insemination in aged broiler breeder hens in two experiments. In the first experiment, the effect of (two) different diluted semen temperatures (5 and 25 °C) of Hubbard rooster (40 roosters, 58 weeks of age) on fertility, hatchability and sperm penetration (SP) rate in the perivitelline layer of Hubbard hen (180 hens) were investigated. In the second experiment, three (different) sperm concentrations (100 (C100), 200 (C200), and 400 (C400) million sperm in 0.25 mL per hen) of Hubbard roosters (40 roosters, 62 weeks of age) on fertility, hatchability and SP rate of Hubbard broiler breeder hens (270 hens) were explored. In the first experiment, the results showed that the temperature of 5 °C of diluted semen compared to the 25 °C, increased percentage of hatchability of set eggs, hatchability of fertile eggs, and SP and decreased early embryonic mortality. The results of the second experiment showed the highest percentage of fertility and SP rate were observed at treatment C400. Also, in this experiment that highest percentage of hatchability of set eggs and hatchability of fertile eggs and lowest early embryonic mortality were observed at treatment C400. Return on investment (ROI) of the treatments C200 and C400 was approximately 2.9 and 1.4, respectively. In overall, the results of this study showed that (in attention to ROI and hatchability) to optimize artificial insemination of aged broiler breeder hens we can use a sperm concentration of 200 to 400 million in 0.25 mL per hens at 5 °C.

The accurate prediction of crack initiation and growth in manufacturing processes is crucial for minimizing production costs and enhancing the reliability of components. This study focuses on integrated experimental investigation and fracture modeling approach for ductile metals, particularly addressing the mechanisms of ductile fracture and shear localization. The importance of establishing robust damage criteria for accurate reliable numerical simulations cannot be denied. Current literature reveals a significant lack of data on shear and ductile fracture criteria for materials like stainless steel alloy 304. To address this gap, a series of experimental tests was conducted to extract the necessary coefficients for these criteria. Various sample geometries were analyzed to investigate the effects of different triaxiality stress states and Loading rates on fracture initiation. The triaxiality stress states were chosen within a range of 0.2 to 2 and strain rates were applied at values of 0.02 s-1, 4.5 s-1, and 30 s-1. A set of coefficients for modeling ductile and shear fracture was derived, taking into account the effects of Loading rate and orientation. This research not only provides critical coefficients for fracture modeling but also supports the optimization of manufacturing processes in the automotive industry and other sectors, ultimately contributing to improved material performance and component reliability

Summary Failure mechanism of rocks is one of the fundamental aspects to study rock engineering stability. The macroscopic deformation and failure of rock is a dynamic, gradual and cumulative process of nucleation, growth, penetration, coalescence of micro-cracks, which is a non-equilibrium, non-linear evolutionary process. In the present study, the effect of Loading rate on rock failure mechanism was considered. For this purpose, some experimental tests were conducted on Brazilian disk specimens of a homogeneous and isotropic sandstone at six different Loading rate (0. 3, 0. 6, 1. 2, 2. 4, 4. 8 and 9. 6 mm/min). During the tests, acoustic emission (AE) sensors were used to monitor the fracturing process. AE monitoring showed that micro-crack density induced by the applied loads during different stages of the failure processes increases as Loading rate increases. Also, it is found that Loading rate influences the mode of induced fracture, so that the number of tensile fractures decreases when Loading rate increases.

Rock masses naturally contain joints and fractures and the effect of these fractures needs to be carefully investigated to ensure the stability of rock structures. This is particularly the case when dynamic Loading effects due to earthquakes or rock blasting are involved. In this study, Brazilian synthetic specimens, made of gypsum with initial notches, were loaded in the mode-I fracture. The specimens were 50 mm in diameter and 10 mm in thickness. The pre-existing notch length in the specimens varied from 10 to 40 mm. The nominal tensile strength of the specimens was numerically evaluated using a bonded particle model (BPM) for the synthetic rock material. The dynamic tests were performed using the Split Hopkinson Pressure Bar (SHPB) system which was numerically simulated by the CA3 computer program. CA3 is a computer program for static and dynamic simulation of geomaterials in which a hybrid bonded particle and finite element system can be employed. The rock specimen was represented by the bonded particle model, while the incident and transmission bars in the Hopkinson Pressure Bar system were simulated by the finite element model. The bonded particle system was calibrated to ensure that the elastic properties, uniaxial compressive strength, tensile strength, and fracture toughness of the rock were replicated by the numerical model. The combined effect of Loading rate and initial fracture length on the rock tensile strength was investigated. The results, as expected, suggest that the static nominal tensile strength of the specimens was reduced as the notch length increased. Under dynamic Loading, the material response is more complicated; depending on the applied stress rate, the tensile strength can decrease, remain constant, or increase as the initial notch length increases. It is shown that the speed of the crack tip opening is responsible for this interesting observation of tensile strength changes under dynamic Loading as the notch length varies.

Unreinforced mass concrete tensile strength is the most important parameter in concrete dams design. Actually, concrete strength is affected by several factors such as section size, type and rate of Loading, and material and mixture properties. As is well known, concrete member tensile strength tends to decrease when its size increases. Obviously, in concrete dams with large sections, this effect is more pronounced. In this study, we aimed to investigate the major changes in the shape and volume of optimal arch dams designed taking into account the factors mentioned above, especially the structural section size effect on concrete resistance. To this end, the apparent tensile strength proposed by Dungar on the basis of Bazant size effect law was used. The results obtained were compared with the designs based on classic or Raphael tensile resistance criterion. To design the dams, CADSO, the software for optimization of arch dam shape, was used, and its design improved in order to apply the aforementioned resistance equations. The new software is able to determine the optimized shape of dam by meeting various constraints, such as tension limitations, resulting from Loading combination conditions including body weight, water pressure, and seismic status while considering sections size and type and rate of Loading. The results of studies on the great Shahid Rajaee Dam suggest that the optimized design based on the principles of fracture mechanics increases the thickness of sections, especially in the tensile stress concentration positions near the foundation. The process changes the optimal shape pattern of the dam body shell increasing its volume, for the case studied. According to the results mentioned, it appears that there is a serious concern with the conventional design of concrete dams; size effect has to be taken into account for the safe design of concrete dams shape.

In this study, four aerobic sequencing batch reactors (SBRs) were operated under the same conditions for the treatment of milk wastewater at different organic Loading rates (OLRs). Cylindrical Plexiglas reactors were run for 56 days (including 21 days of acclimatization and 35 days of data gathering). effective volume, influent wastewater flowrate, and sludge retention time (SRT) of reactors were 5.5 L, 3.5 L/d, and 10 d, respectively. The average COD removal efficiency for the reactors R1, R2, R3, and R4 with influent OLRave values of 633, 929, 1915, and 3261 gCOD/m3d were 95, 96, 95, and 82 percent, respectively. The average effluent suspended solid (SS) for all reactors was lower than 44 mg/L. Also, except for R4 with an average effluent turbidity of 270 NTU, other reactors met the Iranian wastewater emission standard (50 NTU). In addition, the average sludge volume index of reactors R1 to R3 was found to be lower than 67 mL/g. According to the results, the overall variation of COD removal efficiency versus influent OLR shows a decreasing rate with a correlation factor of 0.8 (R2).

Hypotension associated with spinal anesthesia for cesarean section is still a clinical problem. The role of crystalloid preLoading to prevent hypotension associated with spinal anesthesia in parturients during cesarean section has been challenged. However, studies with crystalloids predict that fluid Loading should be more efficacious if administered immediately after induction of spinal anesthesia. The effects of colloid Loading after spinal anesthesia in cesarean section have not been studied enough. The aim of this study was to compare pre and co-Loading of hetastarch for the prevention of hypotension following spinal anesthesia for cesarean delivery.Materials and Methods: This randomized clinical trial study was performed in 112 parturients (ASA I or II) undergoing elective cesarean section. Patients were randomly allocated to one of the two groups to receive rapid infusion of 500 ml of 6% hydroxyethylstarch (HES) before spinal anesthesia (preLoading group, n=56), or rapid infusion of 500 ml of HES after induction of spinal anesthesia (co-Loading group, n=56). The incidence of hypotension and the amount of vasopressor, (ephedrine 5 mg/mL+phenylephrine 25 micg/mL) were compared in the treatment of hypotension.Results: There was no significant difference in hypotension between the two groups (P=0.58). The preLoading group used 2.2±1 ml of vasopressor mixture compared with 1.7±0.7 ml in the co-Loading group (P=0.04) and the difference was significant.Conclusion: Colloid Loading after induction of spinal anesthesia is as effective as preLoading in reducing hypotension in cesarean section.

The aim of this study was to investigate the effect of exercise-induced fatigue on vertical ground reaction force and Loading rate during crossover landing. To do so, 15 healthy men participated in this study. Peak and landing values of ground reaction forces (GRFs), time to reach them and Loading rate in participants before and after were extracted using Kistler force plate. Results showed that the amplitude of the second vertical peak in force (Fz2) (landing GRFs) reduced at toe contact with the ground but the amplitude of the fourth vertical peak in force (Fz4) (landing GRFs) increased at heel contact with the ground. In the fatigued conditions, subjects had faster time to peak of FZ4. Changing the components of GRF and the time to peak of faster to vertical GRF when contacting feet with your ground as a risk factor in the jump or landing. Therefore, providing strategies for preventing this risk factor can play a very important role. Thus, it is suggested that feedback due to changes in these biomechanical parameters complement the treatment and prevention of these risk factors in the activity and rehabilitation of therapists, physiotherapists and other groups.