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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Materials and structures 28 (1995), S. 345-349 
    ISSN: 1359-5997
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying
    Description / Table of Contents: Resume En raison de l'accroissement des besoins en matériaux de construction et de la demande de calculs analytiques des structures, des caractéristiques sont exigées pour les matériaux, y compris pour ceux qui étaient traditionnel-lement utilisés de façon empirique. Ceci est vrai pour le roseau égyptien. Un programme d'essais a permis de déterminer sa résistance uniaxiale à la traction et à la compression, sa résistance statique et sa résistance à la flexion par choc. Le matériau testé(Arundo phragmite), en provenance d'Egypte, a été pré-stocké sous trois conditions d'humidité différentes: saturé à chaud, à température ambiante, et séché à l'étuve. La résistance à la traction moyenne a été d'environ 118 M Pa, la résistance à la compression de 45 M Pa, la résistance à la flexion de 28 M Pa et l'effort de rupture au choc de 43 kJ m−2. La présence de noeuds dans les roseaux s'est avérée importante pour la résistance à la traction et à la flexion, et moindre pour la résistance à la compression et au choc. On a constaté qu'une augmentation de l'humidité réduit la résistance à la flexion, tandis que la résistance à la traction atteint son maximum au stockage à température ambiante. L'influence de la densité apparente sur la résistance à la compression est faible, tandis que la résistance à la flexion s'accroît avec une densité apparente croissante.
    Notes: Abstract A growing need for building materials and an increasing demand for the analytical calculation of structures mean that data are required about materials which were traditionally used on an empirical basis. This is true for Egyptian reed, and tests are reported on its uniaxial tensile and compressive strength, and its static and impact bending strength.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1475-2743
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. In general, agricultural management has focused on differences between fields or on the gross differences within them. Recent developments in agricultural technology, yield mapping, Global Positioning Systems and variable rate applications, have made it possible to consider managing the considerable variation in soil and other properties within fields. This system is known as precision agriculture. More precise management of fields depends on a better understanding of the factors that affect crop input decisions. This paper examines the spatial variation in crop yield, soil nutrient status and soil pH within two agricultural fields using geostatistics. The observed properties vary considerably within each field. The relation between yield and the measured soil properties appears to be weak in general. However, the range of spatial correlation for yield, shown by the variogram, is similar to that of the soil chemical properties. In addition the latter changed little over two years. This suggests that information on the scale of variation of soil chemical properties can be derived from yield maps, which can also be used as a guide to a suitable sampling interval for soil properties.
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2018-09-08
    Description: In many species of finfish, females exhibit higher growth rates than males and achieve larger sizes. In addition, in some species, males mature before reaching marketable size. Therefore, there is great interest from the fish farmers to produce all-female stocks. In this project tried to reversing the sex of rainbow trout larvae by 17 estradiol and direct method, further more finding the optimum dose of this natural estrogen for endocrine sex reversion of Rainbow trout (O. mykiss). Four experimental treatments were designed with doses of 10, 20, 30 and 40 mg/kgf. Trout which treated with 40 mg/kgf yielded 96% female and greatest growth.
    Keywords: Biology
    Repository Name: Aquatic Commons
    Type: Monograph or Serial Issue , NonPeerReviewed
    Format: application/pdf
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  • 4
    Publication Date: 2018-10-05
    Description: Residual level of 17- Beta Stradiol and progesterone hormones in rainbow trout fish plasma were measured during different period using RIA method. Blood sampling from abdominal aorta were taken from 70 individual of female fishes (100±11 g) which had been exposed to hormone at 0.5, 1,2,4,8,12,24 and 168 h (7 groups) compared with control group which was not exposed to this hormone. Results showed that plasma hormones measurement in different fish groups after exposing had significant differences (P〈0.01) and the highest and lowest 17-Beta Stradiol hormone residue were observed in fishes that exposed 0.5h and 168h to hormone respectively (121±9 ng. ml^-1 and 3±0.9 ng. ml^-1) but there is no any differences between fishes exposed 168h to hormone and control group. Also the highest progesterone hormone level were measured in fishes 0.5 an 1h exposed and the lowest one was in fishes 168 h exposed. The range of progesterone hormone were between 0.3 to 1.1 ng .ml^-1 and significant increasing of this hormone levels were obtained in fishes exposed to hormone 4 to 24h (P〈0.01). As consequence these hormone can not residue in fishes for a long time and maximum after one week the levels back to the normal.
    Keywords: Aquaculture
    Repository Name: Aquatic Commons
    Type: Monograph or Serial Issue , NonPeerReviewed
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  • 5
    Publication Date: 2018-10-05
    Description: Breeding has moved beyond the point of simply propagating random stock. Genetic potential can be improved by establishing and crossing genetically defined strains, crossing species and manipulating gametes. Some of these activities require cryopreservation of semen. Cryopreserved sperm could also be a means of exchange of genetic material between locations and populations when transportation of live fish is restricted. In this study we had a survey on rainbow trout sperm quality in Genetic and Breeding Center for Coldwatwr Fishes, Shahid Motahari, Yasouj. Then Cryopreservation trials on rainbow trout (Oncorhynchus mykiss) sperm were carried out using six basic extenders. Egg batches of 25 g were inseminated with semen frozen in five 0.5-ml straws. Thowing temperature of cryopreserved sperm also was tested. In anather trial we investigate different cryoprotectant. The result showd that the best period for sperm collection in this center was from Novamber to January. The best extender based on sperm motility parameters were extender 2 and 1 with 57.2 and 56.9% fertilisatin rates, respectively. So this two extender were used in the further experiments. The best thowing temperathre was 25°C in 30s. Testing different cryoprotectant, adding 10% methanol to extender 1 gave the highest fertilization rate (64.6%) among cryoprotectant that used with this extender. In the other extender (2) adding 5% DMSO and mixture of 5% DMSO and 1% glycerol gave the highest fertilization rates (64.8% and 67.0%, respectively). In conclusion using extender 1 and 2 with mentioned cryoprotectant and thowing rate of 25°C in 30 s was recammended for rainbow trout sperm cryopreservation.
    Keywords: Aquaculture
    Repository Name: Aquatic Commons
    Type: Monograph or Serial Issue , NonPeerReviewed
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  • 6
    Publication Date: 2018-10-13
    Description: Considering the importance of rainbow trout (Oncorhynchus mykiss) in supplying required protein of people and effort to increase the efficiency of these fish reproduction, some related factors such as sperm quality and potential fertility of male are necessary. The aim of this study was to find out the effects of different dosages of Arginine on the biochemical parameters (including LDH, AST, ALT, ALP, iron, magnesium, phosphorous, chloride, calcium, sodium, Potassium, cholesterol, uric acid, urea, fructose, glucose, total protein and pH) of rainbow trout seminal plasma. For this purpose, five practical diets (each consisting of 3 triplicates) were supplemented with Arginine at 0.00 (Control), 0.50, 1.00, 1.50 and 2.00%. Broodstock feed last for 90 days. At the end of the feeding period one fish was captured from each replicate in order to collect their semen. Results indicate that there were no significant differences in LDH, ALP, Fe^2+ and P content among different treatments. The lowest level of AST and ALT and the highest level of Ca^2+ and Mg^2+ ions were observed in the treatment fed with 1.50% of Arginine which showed significant differences with other treatments (p〈0.05). Moreover, the amount of Cl^-, Na^+ and K^+ ions were significantly increased in the seminal plasma in fish which were fed on diets containing arginine in comparison to control. As the amount of Arginine were increased, the levels of uric acid stepped up significantly in contrast to the urea and glucose. The highest amounts of cholesterol, fructose and total protein were observed in the treatments fed on 2.00, 0.50 and 1.00% of Arginine, respectively, that showed significant differences with other treatments (p〈0.05). The highest pH value was assayed in the 1.50% of Arginine treatment. The results of the Pearson correlation coefficient showed a significant positive correlation between Ca^2+ and Mg^2+ ions and Na^+ with K^+ and Clions (r=0.750, r=0.769 and r= 0.938, p〈0.01), respectively. On the other hand, a significant negative correlation between cholesterol with Cl^-, Na^+, K^+, ALT and LDH (r=- 0.764, r=-0.724 and r=-0.728, p〈0.01) and (r=-0.531 and r=-0.560, p〈0.05) and also a significant positive correlation between K^+ and Clions (r=0.836, p〈0.01) were observed. Finally, it can be expressed that the levels of most of the ions were increased and there was a reduction in the levels of enzymes in seminal plasma of fish which were fed with practical diet including 1.5% of Arginine. So it can be recommended that adding this value of Arginine to the diets of rainbow trout broodstock, would improve the sperm quality which results in the enhancement of efficiency in rainbow trout reproduction.
    Keywords: Aquaculture
    Repository Name: Aquatic Commons
    Type: Monograph or Serial Issue , NonPeerReviewed
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  • 7
    Publication Date: 2018-10-13
    Description: The sex reversal technique in fish is widespread in many countries. The development of these techniques is desirable because rainbow trout males reach their gonad maturity earlier compared to the females. Rainbow trout alevins were treated with 17α-methyltestosterone incorporated in the diet (0.5. 1.5, 3, 6 and 10 mg/kg) for 60 days from the beginning of first feeding. Sex was determined at 180 and 680 dpf by sampling fish (n = 20) from each group and examining gross gonadal morphology under a dissecting microscope. Also sex reversal ratio and growth performance were determined in hormone-treated groups. These sex reversed functional males were reared for brood stock until they attained sexual maturity. At the end of experiment, normal rainbow trout eggs were fertilized with the sperms taken from sex reversed males for producing all-female populations. Examination of the results showed that 17α- methyltestosterone was effective in all treatment. The highest sex reversal ratio with 100% was observed in group treated with 0.5, 1.5 and 3 mg/kg 17α- methyltestosterone. The highest live weight ratios were observed in groups fed with 6, 0.5 17α-methyltestosterone and control group. Female progeny produced from the sex reversed males were 100 % in all males that sired offspring. All female trout stocks produced by this method have advantage in rainbow trout culture since the fish is not meant for direct human consumption and is used to generate brood stock, therefore, difference of growth parameters do not influence the success.
    Keywords: Aquaculture ; Biology
    Repository Name: Aquatic Commons
    Type: Monograph or Serial Issue , NonPeerReviewed
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  • 8
    Publication Date: 2008-04-01
    Print ISSN: 0377-2217
    Electronic ISSN: 1872-6860
    Topics: Mathematics , Economics
    Published by Elsevier
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  • 9
    Publication Date: 2020-03-01
    Print ISSN: 0378-4371
    Electronic ISSN: 1873-2119
    Topics: Physics
    Published by Elsevier
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