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The efficiency of phenol degradation via Fenton reaction using mixture of heterogeneous goethite catalyst with homogeneous ferrous ion was analyzed as a function of three independent variables, initial concentration of phenol (60 to 100 mg /L), weight ratio of initial concentration of phenol to that of H2O2 (1: 6 to 1: 14) and, weight ratio of initial concentration of goethite catalyst to that of H2O2 (1: 0.3 to 1: 0.7). More than 90 % of phenol removal and more than 40% of TOC removal were achieved within 60 minutes of reaction. Two separate models were developed using artificial neural networks to predict degradation percentage by a combination of Fe3+ and Fe2+ catalyst. Five operational parameters were employed as inputs while phenol degradation and TOC removal were considered as outputs of the developed models. Satisfactory agreement was observed between testing data and the predicted values (R2
Phenol = 0.9214 and R2TOC= 0.9082). 相似文献
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TÜNDE TÓTH OTTÓ ZSIROS MIHÁLY KIS GYŐZŐ GARAB LÁSZLÓ KOVÁCS 《Plant, cell & environment》2012,35(12):2075-2086
Despite intense research, the mechanism of Cd2+ toxicity on photosynthesis is still elusive because of the multiplicity of the inhibitory effects and different barriers in plants. The quick Cd2+ uptake in Synechocystis PCC 6803 permits the direct interaction of cadmium with the photosynthetic machinery and allows the distinction between primary and secondary effects. We show that the CO2‐dependent electron transport is rapidly inhibited upon exposing the cells to 40 µm Cd2+ (50% inhibition in ~15 min). However, during this time we observe only symptoms of photosystem I acceptor side limitation and a build of an excitation pressure on the reaction centres, as indicated by light‐induced P700 redox transients, O2 polarography and changes in chlorophyll a fluorescence parameters. Inhibitory effects on photosystem II electron transport and the degradation of the reaction centre protein D1 can only be observed after several hours, and only in the light, as revealed by chlorophyll a fluorescence transients, thermoluminescence and immunoblotting. Despite the marked differences in the manifestations of these short‐ and long‐term effects, they exhibit virtually the same Cd2+ concentration dependence. These data strongly suggest a cascade mechanism of the toxic effect, with a primary effect in the dark reactions. 相似文献
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The biodegradable oil absorption resin (B-PEHA) was prepared by suspension polymerization, and its preparation was confirmed by Fourier transform infrared analysis. The oil absorption capacities of the prepared B-PEHA were: chloroform 30.88, toluene 19.75, xylene, 18.78, THF 15.96, octane 11.43, hexane 9.5, diesel oil 12.80, and kerosene 13.79 g/g. The biodegradation of the prepared B-PEHA was also investigated by determination of reduced sugar produced after enzymatic hydrolysis, thermogravimetric analysis, and incubation with Aspergillus niger. The biodegradation of B-PEHA was ~18%. 相似文献
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Real-time determination of kinetics of adsorption of lead(II) onto palm shell-based activated carbon using ion selective electrode 总被引:2,自引:0,他引:2
In this study, the kinetics of adsorption of Pb(II) from aqueous solution onto palm shell-based activated carbon (PSAC) were investigated by employing ion selective electrode (ISE) for real-time Pb(II) and pH monitoring. Usage of ISE was very appropriate for real-time adsorption kinetics data collection as it facilitated recording of adsorption data at very specific and short time intervals as well as provided consistent kinetics data. Parameters studied were initial Pb(II) concentration and agitation speed. It was found that increases in initial Pb(II) concentration and agitation speed resulted in higher initial rate of adsorption. Pseudo first-order, pseudo second-order, Elovich, intraparticle diffusion and liquid film diffusion models were used to fit the adsorption kinetics data. It was suggested that chemisorption was the rate-controlling step for adsorption of Pb(II) onto PSAC since the adsorption kinetics data fitted both the pseudo second-order and Elovich models well. 相似文献
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PETER BOGNER DENYS N. WHEATLEY CSABA BORBLY ATTILA MISETA 《Cell biology international》1996,20(11):741-749
Exchange of erythrocyte intracellular (i/c) K+for extracellular (e/c) Na+in human erythrocytes treated with sub-CMC concentrations of the non-ionic detergent Brij 58 can be stopped by reincubation in serum or albumin containing solutions. The progressive equilibration of the K+contents of detergent-treated human erythrocytes with the incubation medium was reversed by an albumin-mediated withdrawal of detergent molecules from the cell. Re-establishment of near normal [K+] in terms of K+/kg water proceeds in two ways: (i) a metabolism-dependent net accumulation of K+ions; and (ii) a metabolism-independent shrinkage of erythrocytes, this being the more significant factor. 相似文献
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18S rRNA data indicate that Aschelminthes are polyphyletic in origin and consist of at least three distinct clades 总被引:7,自引:1,他引:6
Winnepenninckx B; Backeljau T; Mackey LY; Brooks JM; De Wachter R; Kumar S; Garey JR 《Molecular biology and evolution》1995,12(6):1132-1137
The Aschelminthes is a collection of at least eight animal phyla,
historically grouped together because the absence of a true body cavity was
perceived as a pseudocoelom. Analyses of 18S rRNA sequences from six
Aschelminth phyla (including four previously unpublished sequences) support
polyphyly for the Aschelminthes. At least three distinct groups of
Aschelminthes were detected: the Priapulida among the protostomes, the
Rotifera-Acanthocephala as a sister group to the protostomes, and the
Nematoda as a basal group to the triploblastic Eumetazoa.
相似文献
8.
Chimpanzee fetal G gamma and A gamma globin gene nucleotide sequences provide further evidence of gene conversions in hominine evolution 总被引:5,自引:0,他引:5
The fetal globin genes G gamma and A gamma from one chromosome of a
chimpanzee (Pan troglodytes) were sequenced and found to be closely similar
to the corresponding genes of man and the gorilla. These genes contain
identical promoter and termination signals and have exons 1 and 2 separated
by the conserved short intron 1 (122 bp) and exons 2 and 3 separated by the
more rapidly evolving, larger intron 2 (893 bp and 887 bp in chimpanzee G
gamma and A gamma, respectively). Each intron 2 has a stretch of simple
sequence DNA (TG)n serving possibly as a "hot spot" for recombination. The
two chimpanzee genes encode polypeptide chains that differ only at position
136 (glycine in G gamma and alanine in A gamma) and that are identical to
the corresponding human chains, which have aspartic acid at position 73 and
lysine at 104 in contrast to glycine and arginine at these respective
positions of the gorilla A gamma chain. Phylogenetic analysis by the
parsimony method revealed four silent (synonymous) base substitutions in
evolutionary descent of the chimpanzee G gamma and A gamma codons and none
in the human and gorilla codons. These Homininae (Pan, Homo, Gorilla)
coding sequences evolved at one-tenth the average mammalian rate for
nonsynonymous and one-fourth that for synonymous substitutions. Three
sequence regions that were affected by gene conversions between chimpanzee
G gamma and A gamma loci were identified: one extended 3' of the hot spot
with G gamma replaced by the A gamma sequence, another extended 5' of the
hot spot with A gamma replaced by G gamma, and the third conversion
extended from the 5' flanking to the 5' end of intron 2, with G gamma
replaced here by the A gamma sequence. A conversion similar to this third
one has occurred independently in the descent of the gorilla genes. The
four previously identified conversions, labeled C1-C4 (Scott et al. 1984),
were substantiated with the addition of the chimpanzee genes to our
analysis (C1 being shared by all three hominines and C2, C3, and C4 being
found only in humans). Thus, the fetal genes from all three of these
hominine species have been active in gene conversions during the descent of
each species.
相似文献
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A simple and rapid photometric method was developed in order to evaluate the growth responses of cells to various factors in vitro. Cells of Asparagus officinalis L. were mixed with autoclaved agar at 40°C and 90 l drops were dispensed into several Petri dishes. After the drops solidified, they were covered with a liquid growth medium and incubated on a gyratory shaker. Growth was measured every 2 or 3 days by two methods. In the first, the agar drop was placed under a stereomicroscope with substage illumination and the light passing through the embedded cells was measured by a light-meter. Growth, expressed by the increase in cell density, was inversely proportional to the intensity of transmitted light. In the second method, the agar drop was melted in a microwave oven and the packed cell volume was measured. The correlation between the two methods showed that the photometric method can be used to assess growth response of immobilized cells, during the first two weeks of culture. This method was used to evaluate growth responses to the toxin fusaric acid and to gamma radiation. The photometric method requires a small amount of inoculum, standard microscopic equipment and can be used to determine the effect of various factors on the growth of intact plant cells in vitro without disruption.Abbreviations FA
fusaric acid
- NAA
naphthyl-1-acetic acid
- CH
casein hydrolysate
- 2-i,P
N6-(2-isopentyl) adenine
- 2,4-D
2,4-dichloro-phenoxy acetic acid
- PCV
packed cell volume
- gy
grey 相似文献
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