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1.
Marjan Sedighi-Gilani Homeira Sunderland Parviz Navi 《Wood Science and Technology》2005,39(6):419-430
The pattern and extent of variation of microfibril angle (MFA) in normal and compression tracheids of softwood were investigated
by using confocal laser scanning microscopy technique. All measurements support the idea that the orientation of microfibrils
in single wood tracheids is not uniform. MFA of the radial wall of earlywood tracheids was highly non-uniform and had an approximately
circular form of arrangement around the bordered pits (inside the border). Between the bordered pits the measured MFAs were
less than the other parts of the tracheid. In the latewood tracheids MFA was less variable. The average orientation of simple
pits in the crossfield region was consistent with the mean MFA of the tracheids; however some of the measurements showed a
highly variable arrangement in the areas between the simple pits. In many cases the local measured MFAs of compression wood
tracheids agreed with the orientation of natural helical cavities of compression wood. Comparing the measured results in different
growth rings showed that MFAs in juvenile wood are generally larger than in perfect wood. 相似文献
2.
Micromechanics of wood subjected to axial tension 总被引：5，自引：0，他引：5
Parviz Navi Pramod K. Rastogi Valérie Gresse Ali Tolou 《Wood Science and Technology》1995,29(6):411-429
Summary The behaviour of a small group of wood fibers of Sitka spruce during tensile loading is investigated. The load-extension curves for both early and late wood fibers consist of three distinct segments. The first segment is almost a straight line, at some stage of loading a yield point is observed. Beyond this point the specimen becomes less stiff and undergoes a large, mainly irreversible deformation. As the load is increased further, the curve exhibits the third segment showed by a significant change in slope. These curves look different from those obtained on thick specimens. In this respect, the behaviour of a thin wood specimen subjected to cyclic type tensile loading along its longitudinal direction is also illustrated. Based on wood microstructure, a model is presented to interpret the evolution of the Young's modulus of a wood fiber during tensile loading. The model considers wood as an assembly of cylindrical fibers pasted together in a longitudinal direction. We have assumed the cell wall to comprise only an S2 layer made of a composite material consisting of a lignin and hemicellulose matrix reinforced by helical microfibrils along the fiber. Furthermore, it is assumed that the microfibril angle a in the S2 layer is not uniform along the fiber axis and matrix degradation occurs in the zones where the microfibril angles are bigger. The validity of this assumption is verified by using holographic interferometry to visualize the displacement field of the specimen's surface under tension.The work reported in this paper is supported by a grant from the Swiss National Science Foundation, and its support is gratefully acknowledged 相似文献
3.
Mahdi Naderi Saeed Keyvanshokooh Amir Parviz Salati Alireza Ghaedi 《Fish physiology and biochemistry》2017,43(5):1373-1385
The main aim of the present study was to assess the effects of chronic high stocking density on liver proteome of rainbow trout. Rainbow trout juveniles (42.6 ± 2.3 g average body weight) were randomly distributed into six tanks at two stocking densities (low stocking density (LD) = 20 kg m?3 and high stocking density (HD) = 80 kg m?3). Both treatments were performed in triplicate tanks for a period of 60 days. High stocking density caused a reduction in the growth performance compared with LD fish. Lysozyme activity increased with stocking density, while serum complement activity presented the opposite pattern. Serum cortisol and total protein levels did not show significant differences (P > 0.05) between experimental groups. The fish reared at high stocking density showed significantly lower osmolality and globulin values but higher albumin level. The HD group had significantly higher activities of catalase, glutathione peroxidase and superoxide dismutase, and malondialdehyde content in the liver when compared to the LD group. Comparative proteomics was used to determine the proteomic responses in livers of rainbow trout reared at high stocking density for 60 days. Out of nine protein spots showing altered abundance (>1.5-folds, P < 0.05), eight spots were successfully identified. Two proteins including apolipoprotein A-I-2 precursor and mitochondrial stress-70 protein were found to increase in HD group. The spots found to decrease in the HD group were identified as follows: 2-peptidylprolyl isomerase A, two isoforms of glyceraldehydes-3-phosphate dehydrogenase, an unnamed protein product similar to fructose-bisphosphate aldolase, 78 kDa glucose-regulated protein, and serum albumin 1 protein. 相似文献
4.
5.
In this study, the effects of different background colours on growth performance and physiological parameters of Epinephelus coioides were investigated. One hundred eighty E. coioides (average weight 18.16 ± 0.07 g) were distributed in black, white and blue 300‐L tanks and fed to satiation for 60 days. The tank colour had no significant effect on the weight gain, condition factor, hepatosomatic index and specific growth rate (p > .05). The lowest amount of viscerosomatic index and the highest carcass protein were recorded in the white tank (p < .05). Daily food intake, feed conversion ratio and plasma glucose were significantly higher in the blue tank (p < .05). The highest levels of haematocrit and plasma triglyceride were observed in the white tank, while the total protein and albumin were higher in the black tank compared to the other tanks. The tank colour had no significant effects on the plasma cortisol level (p > .05). Our findings showed that colours used in this study did not evoke stress and thus had no effect on growth, but some metabolic adaptation occurred in each colour to achieve optimum growth. 相似文献
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7.
Fatemeh Ranjbar Parviz Rezvani Moghaddam Alireza Koocheki 《Communications in Soil Science and Plant Analysis》2017,48(7):801-807
Essential oil content and concentration of anise plant planted in different times under various sources of nitrogen was evaluated in this study. The experiment was conducted in a split plot based on a randomized complete block (RCB) design (different sources of fertilizer as the main plot and planting dates as subplots) with three replications in the Agricultural Research Station at Ferdowsi University of Mashhad in 2015–2016. Treatments included: planting times (sub plot factor): (27th of October, 27th of November, 1st of March, 10th of March, and 8th of April) and nutritional sources (main plot factor): (Cow Manure, Chemical Fertilizer, and mixture of Cow Manure + Chemical Fertilizer). The results showed that the anise plant essential oil qualitative characteristics were significantly influenced by treatments. Also, interaction between the fertilizer treatments and planting dates on the essential oil content and concentration of the plants were significant. The highest percentage of plant essential oil (3.71%) was found in the cow manure treatment, and the lowest percentage of essential oil (2.95%) was obtained in the chemical fertilizer. The highest essential oil yield (16.09 kg/ha) was found in the mixed treatment of the cow manure and the chemical fertilizer, and the chemical fertilizer treatment had the lowest rate of essential oil yield (11.41 kg/ha). The highest percentages of the plant oil (14.31%) and the plant oil yield (77.46 kg/ha) were found in the integrated treatment of the cow manure and the chemical fertilizers. The lowest amounts of the plant oil (12.19%) and the plant oil yield (41.28 kg/ha) were found in the chemical fertilizer. According to the percentage and the yield of the essential oil, the best planting time and fertilizer treatment was the one on 10th of March and using integrated cow manure and chemical fertilizer. 相似文献
8.
Bahareh Azimi Parviz Nourpanah Mohammad Rabiee Shahram Arbab 《Iranian Biomedical Journal》2014,18(1):34-40
Background: Progress in the field of biology and biochemistry has led to the discovery of numerous bioactive peptides and proteins in the last few decades. Delivery of therapeutic proteins/peptides has received a considerable amount of attention in recent years. Methods: In this study, a two-step desolvation method was used to produce biodegradable hydrophilic gelatin nanoparticles (GNP) as a delivery system of protein model (BSA). The size and shape of the nanoparticles were examined by dynamic light scattering and scanning electron microscopy. Results: Particles with a mean diameter of 200-300 nm were produced and the percentage of entrapment efficiency was found to be 87.4. The optimum amount of theoretical BSA loading was obtained, the release of BSA was monitored in vitro, and the mechanism of release was studied. The BSA release profile showed a biphasic modulation characterized by an initial, relatively rapid release period, followed by a slower release phase. Conclusion: Results show that the two-step desolvation is an appropriate method for preparing GNP as a delivery vehicle for BSA. Key Words: Gelatin, Nanoparticles, Bovine serum albumin 相似文献
9.
大豆叶部病害研究的简易离体叶片培养技术 总被引：6，自引：0，他引：6
为寻找简易有效的大豆叶部病害研究方法,利用大豆离体叶片,进行了相关试验.试验结果表明,大豆离体复叶培养30 d,新根长达16.8～41.2 cm,平均根长》24 cm,移至营养杯30 d后,叶色及叶片仍保持完好.经离体叶片法和整株法接种大豆锈病病原菌后,不同品种和不同菌株表达出不同的病斑反应型;接种大豆白粉病病原菌,也同样表达出在不同品种和不同接种浓度条件下,大豆白粉病发生程度不同;两种接种方试验结果一致.本方法试验条件可控、易控,省时,省空间,因此可考虑应用于大豆叶部病害研究的各种试验. 相似文献
10.
Journal of Plant Diseases and Protection - Remote detection of aerial parasitic plants in forests is imperative in precision forestry, as it can help to manage tree stands and to monitor forest... 相似文献