Micromechanical approach to wood fracture by three-dimensional mixed lattice-continuum model at fiber level

To investigate the fracture behavior of wood, the porosity and heterogeneities of its microstructure should be taken into account. Considering these features of wood microstructure in a continuum-based model is still a difficult problem and the lattice model might be an alternative. In the developed mixed lattice-continuum model, the probable crack propagation volume was modeled by defining a three-dimensional lattice of different beam elements and the other regions were considered as continuum medium. Different beam elements of lattice represented the earlywood fibers, latewood fibers, ray cells and bonding medium between the fibers. The proposed model was used to investigate the mechanism of mode I fracture in a small notched wood specimen in RL orientation. The resulting pre-peak and softening curve and also the crack opening trajectory in both cross-section and longitudinal-section in model were in good agreement with the experimental observations. This model shows the importance of considering the three-dimensional and distributed propagation of microcracks and main cracks in fracture stability. It was also shown that in mode I fracture, RL orientation, the main crack propagates in the earlywood ring.     

Influence of seed nitrogen content and biofertilizer priming on wheat germination in salinity stress conditions

In order to study the effects of seed nitrogen content and biofertilizer priming on germination indices of wheat seeds under salinity stress, a factorial experiment based on a completely randomized design with four replications was conducted in 2009. Experimental factors consisted of: (1) the application of different nitrogen fertilizer rates (0, 55, 110 and 165 kg ha^?1 N) on parent plants; (2) priming of achieved seeds by biofertilizers (Nitragin, Biophosphorus and distilled water); and (3) different levels of salinity produced by NaCl (0, ?0.4, ?0.8 and ?1.2 MPa). Germination percentage, germination rate, mean germination time, germination index, radicle and plumule length, radicle and plumule dry weight and radicle number per seedling were measured. Nitrogen application increased seed nitrogen content in parent plants. All germination indices decreased with increasing in salinity levels. Biofertilizer priming, especially Nitragin, had a positive effect on germination percentage, radicle number and radicle and plumule length in most salinity levels. The highest values for germination factors were related to achieved seeds from parent plants that were treated with 110 kg ha^?1 N. Overall, application of middle levels of N fertilizer (55 and 110 kg ha^?1 N) on parent plants combined with seed priming with Nitragin biofertilizer improved the germination indices of wheat under salinity stress.     

A comparative study of inhibitory effect of human calprotectin on the growth of human gingival fibroblast and foreskin fibroblast

In the present study, cytotoxicity effects of calprotectin on Human Gingival Fibroblast (HGF) and Human Foreskin Fibroblast (HFFF) were compared. For these evaluations, both cells were exposed to the different concentrations of calprotectin, for 24, 48 and 72 h. Cell proliferation was assessed using MTT assay. Our results revealed that growth inhibition of calprotectin on HGF and HFFF occur in a dose- and time-dependent manner. Results of this investigation showed that sensitivity of HGF cells to cytotoxic effect of human calprotectin was more than HFFF. The results indicate that drug resistance process is different for the two kinds of fibroblast cells.     

Interactive effects of dietary Nano selenium and vitamin E on growth,haematology, innate immune responses,antioxidant status and muscle composition of rainbow trout under high rearing density

A 60‐day feeding trial was conducted to evaluate effects and interactions of dietary Nano selenium (Nano Se) and vitamin E on performance of rainbow trout under high rearing density (80 kg/m³). Fish (42.6 ± 2.3 g) were stocked into 12 tanks: Control group fed basal diet and three treatment groups fed basal diet supplemented with 1 mg/kg Nano selenium (Nano Se group), 500 mg/kg vitamin E (Vit E group) and both micronutrients (Combination group). Results showed that growth, feed intake, lysozyme activity and agglutination antibody titre were significantly higher in Vit E and Combination groups. The lowest haematocrit, haemoglobin and cortisol levels and highest serum total protein and muscle crude protein were observed in Combination group. Serum globulin content was higher and albumin: globulin ratio was lower in treatment groups compared with Control. Also, the highest muscle catalase, superoxide dismutase and glutathione peroxidase activities and lowest malondialdehyde content were observed in Combination group compared with Control. In conclusion, combined supplementation of Nano Se and vitamin E provides a synergistic interaction in preventing the immunosuppressive action of oxidative stress caused by high density and significantly improved antioxidant and immune systems, health status and growth of fish under intensive culture.     

Effects of dietary green tea (Camellia sinensis L) on acute stress responses in sturgeon hybrid (Huso huso ♂ × Acipenser ruthenus ♀)

In aquaculture practices, fish commonly confront environmental alterations and unavoidable stresses. Thus, any substance that could attenuate stress responses could be potentially used in aquaculture. A total number of 90 hybrid sturgeons (Huso huso ♂ × Acipenser ruthenus ♀) with an average weight of 212.6 ± 0.7 g were fed experimental diets containing 0, 50 and 100 mg kg^?1 green tea (Camellia sinensis L) for 6 weeks. Subsequently 15 fish from each treatment were exposed to air for 5 min prior to transfer to the recovery tank. Followed by blood sampling after 1, 2, 5 and 12 h, Serum cortisol increased in all treatments, but the intensity was significantly lower in fish fed green tea compared to the control group. Similarly, the green tea diet attenuated the increase in serum levels of glucose and lactate in comparison to the control. Our results showed that green tea could be added to fish diet to attenuate stress responses in Sturgeon hybrid (Huso huso ♂ × Acipenser ruthenus ♀).     

Changes of vitellogenin and Lipase in captive Sterlet sturgeon <Emphasis Type="Italic">Acipenser ruthenus</Emphasis> females during previtellogenesis to early atresia

Plasma chemistry, lipid metabolism and vitellogenin gene expression of captive Sterlet sturgeon Acipenser ruthenus were studied in different maturity stages. A total of 32 fish were sampled, and maturity stages were identified on the basis of histological criteria and direct observation. Females were classified to four groups: previtellogenic, vitellogenic, post-vitellogenic, and atresia. Blood, gonad and liver tissue samples were taken through non-lethal biopsy. Our results showed that plasma levels of glucose, cholesterol, triacylglycerol, high-density lipoprotein, low-density lipoprotein, very low-density lipoprotein, calcium, phosphorus, alkaline phosphatase activity, albumin and total protein increased during ovarian development and were highest at post-vitellogenic stage. The lowest amounts in atresia stage demonstrate that lipid and energy imbalance was related to reabsorption and digestion of the yolk. These results suggested that the VLDL was the main plasma lipoprotein component of Sterlet. We determined that lipoprotein lipase and hepatic lipase activity increased during vitellogenesis process which suggested the role of lipase enzymes in regulating blood lipid metabolism. RT-PCR analysis indicates that Vitellogenin (VTG) mRNA could be detected both in livers and ovaries of female Sterlet. Throughout the study, the expression level of VTG gene showed an increase both in ovaries and in livers reaching its peak at late vitellogenesis stage. This strongly indicated a relation between VTG mRNA and ovarian development.     

A new PCR-RFLP method for detection of <Emphasis Type="Italic">Anaplasma marginale</Emphasis> based on 16S rRNA

Species of the genus Anaplasma (Rickettsiales: Anaplasmataceae) are obligate intracellular tick borne pathogens. Three species of Anaplasma that infect cattle and sheep (A. marginale, A. centrale and A. ovis) are well recognized. Of these erythrocytic Anaplasma, A. marginale can cause diseases in the livestock with high economical losses. Species-specific PCR based on 16S rRNA gene is commonly used for detection of Anaplasma species but can not differentiate A. marginale, A. centrale and A. ovis because of sequence similarity. In this study DNA extraction was performed on 50 blood samples with presence of Anaplasma spp. in marginal point of erythrocytes in their blood smears. The extracted DNA from blood cells was analyzed by PCR and PCR-RFLP using primers derived from 16S rRNA gene and restriction endonuclease Bst1107 I. The restriction endonuclease Bst1107I only recognizes the sequence (GTATAC) in corresponding PCR product of A. marginale and cut it. The nucleotide sequence of the A. marginale 16S rRNA gene was determined and compared with the sequences of A. marginale in GenBank. The 16S rRNA of A. marginale in Iran was completely similar to the related sequence deposited in GenBank at accession number of M60313. In the present study we propose a new PCR-restriction fragment length polymorphism analysis (RFLP) method based on 16S rRNA gene for specific detection of A. marginale.