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Opencast coalmine effluent contains higher concentrations of Cd, Cr, Co, Ni and Pb. Biofiltration of these metals has been demonstrated successfully with the help of aquatic macrophytes i.e., E. crassipes, L. minor and A. pinnata. Experiments revealed E. crassipes reduced highest concentration of heavy metals followed by L. minor and A. pinnata on 20th days retention period. Plant tissue analysis revealed higher accumulation of metals in roots than leaves. Highly significant correlations have been noted between removal of heavy metals in effluent and their accumulation in roots and leaves of the experimental sets. Translocation factor also revealed lower transportation of metals from root to leaves. Reduction in chlorophyll and protein content was noted with the accumulation of heavy metals. N, P and K analysis in plant tissues indicated continuous decrease in their concentration with increasing metal concentration. Negative and significant correlations between metal accumulation and N, P and K concentrations in plant tissues showed adverse effects of heavy metals. Analysis of variance (Dunnett t-test) showed significant results (p?<?0.001) for all the metals in different durations. 相似文献
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A toxin was isolated from Bordetella avium grown in a defined medium. The toxin was active for mice but not for turkey poults or Japanese quail. The extraction procedure is described. The toxin was trypsin-sensitive and heat-stable (85 C for 30 min), and its activity was blocked by B. avium hyperimmune serum. 相似文献
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NH Bonadeo J Erland D Gammon D Park DS Katzer DG Steel 《Science (New York, N.Y.)》1998,282(5393):1473-1476
Picosecond optical excitation was used to coherently control the excitation in a single quantum dot on a time scale that is short compared with the time scale for loss of quantum coherence. The excitonic wave function was manipulated by controlling the optical phase of the two-pulse sequence through timing and polarization. Wave function engineering techniques, developed in atomic and molecular systems, were used to monitor and control a nonstationary quantum mechanical state composed of a superposition of eigenstates. The results extend the concept of coherent control in semiconductors to the limit of a single quantum system in a zero-dimensional quantum dot. 相似文献
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KS Johnson JH Thywissen NH Dekker KK Berggren AP Chu R Younkin M Prentiss 《Science (New York, N.Y.)》1998,280(5369):1583-1586
The spatially dependent de-excitation of a beam of metastable argon atoms, traveling through an optical standing wave, produced a periodic array of localized metastable atoms with position and momentum spreads approaching the limit stated by the Heisenberg uncertainty principle. Silicon and silicon dioxide substrates placed in the path of the atom beam were patterned by the metastable atoms. The de-excitation of metastable atoms upon collision with the surface promoted the deposition of a carbonaceous film from a vapor-phase hydrocarbon precursor. The resulting patterns were imaged both directly and after chemical etching. Thus, quantum-mechanical steady-state atom distributions can be used for sub-0.1-micrometer lithography. 相似文献
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The present survey was conducted to isolate and characterize Streptomyces species from common scab lesions of potato in Norway. Bacteria were isolated from scab lesions on tubers sampled in two consecutive years at different locations in Norway spanning ~1400 km from south to north. In total, 957 independent isolations from individual tubers were performed, with 223 putative pathogenic isolates obtained from 29 different potato cultivars and 130 different fields. Streptomyces europaeiscabiei was the most abundant species isolated from common scab lesions (69%), while 31% of the isolates obtained were S. turgidiscabies. Streptomyces scabies was not found. Pathogenicity of selected Streptomyces isolates was tested on potato. The ability of the bacterial isolates to infect potato was consistent with the presence of the txtAB operon. The results revealed no pattern in geographical distribution of S. europaeiscabiei and S. turgidiscabies; both could be found in the same field and even the same lesion. Four different pathogenicity island (PAI) genotypes were detected amongst the txtAB positive isolates: nec1+/tomA+, nec1–/tomA+, nec1+/tomA? and nec1?/tomA?. The current findings demonstrate that there is genetic variability within species and that the species are not spread solely by clonal expansion. This is thought to be the most comprehensive survey of Streptomyces species that cause common scab of potato in a European country. 相似文献
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Aspergillus spp. panophthalmitis with intralenticular invasion in dogs: report of two cases
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This case series describes the ocular, clinical and histologic manifestations of disseminated Aspergillosis in two dogs. Two dogs presented for severe unilateral panophthalmitis and secondary glaucoma with positive Aspergillus spp. titers. Case 1 showed no clinicopathologic systemic symptoms of fungal dissemination, however, case 2 was affected with acute renal failure. The affected eye of case 1 did not respond to medical therapy and was enucleated for comfort. The affected eye of case 2 responded to aggressive topical and systemic medical therapies, however, the patient was euthanized for acute renal failure. Globes were collected for histologic evaluation at the time of death. Histology of both revealed panophthalmitis with presence of significant intraocular hemorrhage, multifocal fungal granulomas, retinal and optic nerve changes consistent with secondary glaucoma, rupture of the anterior lens capsule, and fungal invasion and colonization of the intralenticular space. These cases represent a unique and devastating ocular manifestation of disseminated Aspergillosis. Cases presenting with uveitis and secondary glaucoma of unknown origin, especially with confirmed or suspected lens capsular rupture, should have serologic testing for this infectious agent. 相似文献
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