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1.
H E Shams el Din M el Nasri 《Revue d'élevage et de médecine vétérinaire des pays tropicaux》1990,43(3):323-324
Seventeen isolates (4.27%) were recovered from 398 samples. Twelve isolates (4%) were obtained from 300 donkey nasal swabs, three (4.3%) and two (6.89%) isolates were recovered from 69 horse nasal swabs and 29 mare uterine washings, respectively. Nine isolates were lost during storage at -20 degrees C and the remaining eight were identified as mycoplasmas and their biological, biochemical and serological reactions were investigated. The isolates could be divided into two groups on the basis of glucose fermentation and arginine hydrolysis. The first group neither fermented glucose nor hydrolysed arginine. Organisms in the second group hydrolysed arginine only. 相似文献
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The antifungal activity of onion (Allium cepa L.) on two important dermatophytes, Trichophyton rubrum and Trichophyton mentagrophytes, with special reference to morphological aspects was studied. Growth of both fungi was found to be strongly inhibited by aqueous onion extract (AOE) as a dose-dependent manner. The extract showed fungicidal effect for both fungi at concentrations >3.12% (v/v). The fungus T. mentagrophytes was more affected by the onion as compared to T. rubrum at all concentrations used. Morphological effects of onion exposure were examined in correlation with fungal growth. Corresponding to the growth inhibition, light and electron microscopy observations revealed morphological anomalies in hyphal compartments. The results demonstrated that AOE targets the cell membrane of the fungi as breaking down of both inner and outer membranes with consequent extrution of materials into the surrounding medium. Cytoplasmic membranes and other membranous structures of organelles, such as nuclei and mitochondria, were also disrupted. In correlation to the fungal growth, morphological alterations occurred to a less content for T. rubrum compared with T. mentagrophytes. The hyphae of T. rubrum were found to be mainly affected by converting to resistant forms, i.e., chlamidospores as a consequence of phenotype switching response to AOE. Plasmolysis accompanied by an almost complete depletion and disorganization of cytoplasmic structures were found to be the final event which led to cell death. Ultrastructural evidences obtained from this study strongly support that morphological changes of T. rubrum and T. mentagrophytes caused by AOE are associated with its fungistatic and fungicidal activities. With respect to the morphological results and the preliminary data on fungal biochemistry, a mechanism of action by interacting of AOE with thiol (-SH) groups present in essential compartments of the fungal cells was postulated. 相似文献
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Immobilized microbial cells for the biological treatment have the potential to degrade toxic chemicals faster than conventional wastewater treatment systems. In the present study, suitability of immobilized Pseudomonas fluorescens SM1 strain in calcium alginate beads for remediation of the major toxicants in Indian water bodies was tested by means of GC/HPLC and AAS techniques. Roughly 80% reduction in the concentration of phenols was observed by immobilized SM1 cells compared with 60% by the free cells. Also, in the case of the bioremediation of heavy metals, immobilized SM1 cells were found to be more efficient compared with the free cells. Suspension of P. fluorescens SM1 cells in the test model water for 24 h brought down the concentrations of Cu++, Cd++, Ni++, and Pb++ by more than 75% under free cell state and 7?C9% better efficiency under the immobilized conditions. However, Cr(VI) could show only 44% removal by the cell immobilized system, whereas a mere 35% reduction in the Cr(VI) levels was shown in the test model water by the free SM1 cells under the same conditions. Moreover, a model water containing 2,000 ppb of BHC, 1,248 ppb mancozeb, and 312 ppb 2,4-D passed through the cell immobilized column resulted in the decline in their concentrations up to 362 ppb, 750 ppb, and 126 ppb, respectively. Generally, AAS, HPLC, and GC analyses of treated test model waters with the free and immobilized SM1 cells exhibited high potential of immobilized SM1 in detoxification of test water. From the results, we conclude that immobilized cells of P. fluorescens SM1 strain were quite effective in bioremediation of major toxicants present in Indian water bodies, and we also recommend the use of immobilized bacterial cells rather than the free cells for the bioremediation/detoxification process. 相似文献
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Compressive deformation of wood impregnated with low molecular weight phenol formaldehyde (PF) resin III: effects of sodium chlorite treatment 总被引：1，自引：0，他引：1
To obtain high-strength phenol–formaldehyde (PF) resin-impregnated compressed wood at low pressing pressure, we investigated the effects of sodium chlorite (NaClO2) treatment on wood prior to low molecular weight PF resin impregnation. Sawn veneers of Japanese cedar (Cryptomeria japonica) were treated with 2% aqueous NaClO2 solution at 45°C for 12 h to remove lignin, and the process was repeated up to four times, resulting in weight loss of 21%. NaClO2 treatment has shown considerable potential for high compression of PF resin-impregnated wood at low pressing pressure, especially after adding moisture to a content of 10%–11%. This deformation is further enhanced during pressure holding by creep deformation. The density, Young’s modulus, and bending strength of PF resin-impregnated veneer laminated composites that were treated with NaClO2 four times and compressed at 1 MPa, reached 1.15 g/cm3, 27 GPa, and 280 MPa, respectively. The values in untreated PF resin-impregnated wood reached 0.8 g/cm3, 16 GPa, and 165 MPa, respectively. 相似文献
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Prof. Dr. H. S. Salama M. R. Saleh S. Moawed A. Shams El-Din 《Journal of pest science》1990,63(5):100-102
Field experiments have been carried out to evaluate the potency of the biological control agentBacillus thuringiensis (Dipel), the pyrethroid Fenvalerate and their combinations for the control of the lesser cotton leafwormSpodoptera exigua on soybeans in Qualubia governorate. Molasses was combined with all treatments to enhance their effectiveness. One spray application with either Dipel or Fenvalerate showed an obvious reduction in larval counts ofS. exigua, associated with a significant increase in the crop yield but in varying degrees, in correlation with the tested dose. Treatments with combinations of both biological and chemical insecticides at the lowest tested doses (62 g ofB. t. +50 ml of Fenvalerate/feddan) showed to be highly potential, and caused 2.8 fold increase in the crop yield. It may be recommended that a combination of both preparations may be used for the control ofS. exigua. 相似文献
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Ashmawy Nader A. El-Bebany Ahmed F. Shams Amany H. M. Shoeib Alia A. 《植物病害和植物保护杂志》2020,127(2):141-153
Journal of Plant Diseases and Protection - The bacterial genera Pectobacterium, Dickeya and Enterobacter are plant pathogens that cause soft rot and blackleg of potato. In the present study, 25... 相似文献
8.
- River barrier removal is used increasingly as a conservation tool to restore lotic habitat and river connectivity, but evidence of its efficacy is incomplete. This study used a before–after methodology to determine the effects of removing a tidal-limit barrier on the fishes, macroinvertebrates, and habitats of an English coastal stream.
- Following barrier removal, habitat diversity increased immediately upstream and remained similar downstream. Mobilized silt altered the substrate composition immediately downstream, but this was temporary as silt was flushed out the following winter. Changes to macroinvertebrate communities occurred upstream and downstream of the former barrier but these were transient.
- A dramatic and sustained increase in fish density occurred immediately upstream of the barrier after its removal, but effects downstream were minor. The fish community upstream changed, largely due to rapid recruitment and dispersal of endangered European eel (Anguilla anguilla). Eel density in the formerly impounded zone increased from 0.5 per 100 m2 before barrier removal to 32.5 per 100 m2 5 months after removal. By 17 months after barrier removal there was no difference in eel density across the six sections sampled.
- Although resident stream fishes such as bullhead (Cottus gobio species complex, protected under the European Habitats Directive) were abundant in middle and upper-stream sections, brown trout (Salmo trutta, a listed species for biodiversity conservation in England and Wales) density remained low during the study and recruitment was poor. This suggests that although colonization access for anadromous trout was available, habitat upstream may have been unsuitable for reproduction, indicating that wider catchment management is required to complement the restoration of connectivity.
- These findings suggest that tidal barrier removal is an effective method of restoring lotic habitats and connectivity, and can be beneficial for resident and migratory fishes including those of conservation importance (e.g. European eel) in coastal streams.
9.
The effects of molecular weight of PF resin on the deformation behaviour of NaClO2 treated resin-impregnated wood during compression were investigated. Blocks of Japanese cedar were subjected to 2% NaClO2 aqueous solution. This was repeated up to four times resulting in a weight loss of 28%. Treated and untreated samples were
impregnated with PF resin having different molecular weight. With increasing molecular weight, weight gain and volume gain
decreased for untreated PF resin-impregnated wood, while NaClO2 treated wood impregnated with high molecular weight PF resin showed almost double the weight gain compared to untreated condition.
NaClO2 treatment has shown considerable potential for high compression of PF resin-impregnated wood at lower pressing pressure regardless
of the molecular weight of the resin. Low to high molecular weight resin was shown to penetrate into NaClO2 treated wood as estimated by weight gain contributing to the plasticization of cell wall considerably and thus resulting
in cell wall collapse at low pressing pressure. The density of NaClO2 treated wood impregnated with high molecular weight resin attained a value of over 0.8 g/cm3 which is close to the density of untreated wood impregnated with low molecular weight resin. Such compressed wood exhibited
high dimensional stability after boiling for 3 h. Thus, the penetration of resin into wood contributes to highly compressed
dimensional stable resin-impregnated wood at low pressing pressure. 相似文献
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Mostafakamal Shams Massoumeh Abbassi Niasar Ehsan Zandi Esfahan 《Archives of Agronomy and Soil Science》2013,59(8):1115-1124
Different amounts of nitrogen (N) and copper (Cu) in the forms of urea and copper sulfate (CuSO4·5H2O) were applied and their effects on diosgenin production and dry matter yield in fenugreek were investigated under farm cultivation conditions. High-performance liquid chromatography (HPLC) was employed to analyze diosgenin content. Diosgenin contents were measured in 25, 45 and 65 day-old leaves and in leaves at flowering stage and in fruits. The maximum diosgenin content was obtained in 45 day-old leaves. The results showed that simultaneous addition of Cu and N and the level of supply had significant effects on diosgenin production in leaves, fruits and dry matter yield. Simultaneous use of urea (100 kg ha?1) and copper sulfate (30 kg ha?1) increased diosgenin production and dry matter yield in 45 day-old leaves for 7.72 and 1.32 times, respectively, compared to unfertilized control group. But, the use of higher amounts of urea and copper showed a decrease in diosgenin production. 相似文献