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排序方式: 共有526条查询结果,搜索用时 31 毫秒
1.
Appropriate final disposal of sewage sludge (SS) generated by wastewater treatment plants (WWTP) has been considered a serious environmental problem, but also a viable alternative to be applied in agriculture, once SS is rich in organic matter and nutrients. However, SS can be a source of contamination of several toxic agents. Therefore, its use in agriculture requires special care to avoid possible damage to the environment and exposed organisms. Detoxification of toxic wastes can be performed using the monitored natural attenuation, which involves biological, physical and chemical processes that frequently occur in the environment. This study aimed to assess the feasibility of decontaminating SS after different periods of monitored natural attenuation. To this end, samples of SS and associations of soil/SS with proportions of 10, 25 and 50% SS were buried for 0, 2, 6 and 12 months in holes prepared in a place free of contamination. Allium cepa was used as an indicator to assess the efficiency of the natural attenuation process. According to chemical analysis, the SS samples presented a high concentration of m- and p-cresol, especially for samples analyzed after 0 or 2 months of natural attenuation. The microorganisms present in the SS belonged to 17 different genera of bacteria, which varied in the microbial composition among samples. Both, raw SS and aqueous SS extracts induced DNA damage in A. cepa, even when associated with soil. However, this effect was observed to decline during the attenuation period, although significant effects were detected for the highest tested concentration (100% SS) even at the end of this process. These results thus indicated the necessity of applying a stabilization process associating SS and soil for a period of at least 12 months and showed that the studied raw SS is not a viable material for use as a soil reconditioner, even after natural attenuation. A. cepa test proved to be a useful tool to assess the efficiency of SS detoxification process. Therefore, we suggest that the application of SS in agriculture should be approached with caution and that the SS must be previously submitted to methodologies that evaluate its toxic potential. 相似文献
2.
《Nucleosides, nucleotides & nucleic acids》2013,32(5-7):601-605
A novel approach for the synthesis of 5′-capped 2′-O-methyloligoribonucleotides on a disulfide-tethered solid support is described. The key step of the synthesis is ZnCl2 promoted coupling of m7GDP imidazolide to a fully deprotected oligonucleotide 5′-phosphate on-support. By this methodology m7G5′pppm2′Apm2′Upm2′Ap has been prepared. 相似文献
3.
I. D. Bassukas G. Vester B. Maurer-Schultze 《Virchows Archiv. B, Cell pathology including molecular pathology》1990,59(1):251-256
Cell kinetic studies of endothelial cells in the adenocarcinoma EO 771 growing in C57bl/6j mice and after transplantation
into Balb/c-nu/nu mice, as well as of the effect of cyclophosphamide treatment have been carried out. The3H-thymidine labelling index of endothelial cells decreases from about 8% 3–6 days after tumour inoculation to about 3% at
18 days. This decrease parallels that of the labelling index of tumour cells, i.e. there is a positive correlation between
the labelling index of endothelial cells and that of tumour cells. The labelling index of endothelial cells in the tumour
periphery is two to three times as high as that in the tumour centre reflecting corresponding differences in the rate of proliferation.
There is no difference in the proliferation of endothelial cells whether the tumour grows in C57bl/6j or in Balb/c-nu/nu mice.
After treatment with cyclophosphamide the labelling index of endothelial cells decreases within 2 days to 1–2% and remains
that low despite regrowth of the tumour with increased tumour cell proliferation, indicating that tumour relapse does not
depend on tumour angiogenesis. 相似文献
4.
Y. W. Han D. J. Gallagher A. G. Wilfred 《Journal of industrial microbiology & biotechnology》1987,2(4):195-200
Summary Phytase production byAspergillus ficuum was studied using solid state cultivation on several cereal grains and legume seeds. The microbial phytase was used to hydrolyze the phytate in soybean meal and cotton seed meal. Wheat bran, soybean meal, cottonseed meal and corn meal supported good fungal growth and yielded a high level of phytase when an adequate amount of moisture was present. The level of phytase production on solid substrate was higher than that obtained by submerged liquid fermentation. Higher levels of phosphorus (more than 10 mg Pi/100 g substrate) in the growth medium (static culture) inhibited phytase synthesis, and the degree of phosphorus inhibition was less apparent in semisolid medium than in liquid medium. A static cultivation on semisolid substrate produced a higher level of phytase (2-20-fold) than that obtained by agitated cultivation. The minimal amount of water required for growth and enzyme production on those substrates was about 15%, while the optimum level for phytase production was between 25 and 35% and that for cell growth was above 50%. Optimum pH for phytase production was between 4 and 6.A ficuum grew well on raw (unheated) substrate containing a minimal amount of water and produced as much phytase as on heated substrate. About half of the phytic acid in soybean meal and cottonseed meal was hydrolyzed by treatment withA. ficuum phytase. 相似文献
5.
工业固体废弃物的急性生物毒性研究 总被引:7,自引:0,他引:7
工业固体废弃物的急性生物毒性研究谢思琴,顾宗濂,周德智(中国科学院南京土壤研究所,南京210008)Acutebiotoxicityofindustrialsolidwastes¥.XieSiqin;GuZonglianandZhouDezhi(In... 相似文献
6.
7.
The occurrence of Chara connivens (Charophyta, Characeae) and its status in the Baltic Sea may raise controversies regarding its origin and historical dispersal pathways in the area. This study critically revises the protection status of C. connivens in the countries around the Baltic Sea, as well as its status on the red lists of endangered plant species (including the HELCOM Red List). The first reports on the presence of C. connivens in the Baltic Sea area were published in the aftermath of Carl Baenitz’s talks given in the early 1870s. Already then, the scientific community was well aware of the fact that C. connivens had been introduced as a ballast plant to the known Baltic areas of occurrence – the first known record of the species is from 1829. Since Poland is the only country where C. connivens is protected, the historical and contemporary distribution of this charophyte in the Polish coastal waters is presented against the background of the available historical and recent records of the species in the Baltic Sea. Recent reports from the second half of the 20th century and the beginning of the 21st century have confirmed a fairly common occurrence of C. connivens in Estonia, Sweden and Poland. This species still occurs on the German coast and has also been reported from Finland (the Åland archipelago). In recent decades, however, the species was considered rare in the Baltic Sea area. In Poland, C. connivens was even classified as extinct, despite earlier data on its occurrence in the Vistula Lagoon in the 1970s, where it was rediscovered in 2011. It was also found in the Szczecin Lagoon a year later. Both localities well suit Luther’s pattern of C. connivens occurrence in areas with intensive shipping and ballast discharge operations in historical times. Based on this in-depth revision of historical and current distribution, it is postulated that C. connivens, as non-indigenous, should not be red-listed in the Baltic Sea area, following the example of Finland. Moreover, its legal status in Poland of a strictly protected species should be reconsidered. 相似文献
8.
Christian Bonhomme Jocelyne Maquet Jacques Livage Gino Mariotto 《Inorganica chimica acta》1995,230(1-2):85-95
Seven new mono- and/or dimercurated compounds involving acetylacetone (2,4-pentanedione) or ethyl acetoacetate (3-ethyl ketobutanoate) were synthesized in aqueous medium. In all cases, mercuration occurred at methylene carbon atoms. All compounds were carefully analyzed by solid state carbon-13 nuclear magnetic resonance. Assignments were confirmed by using selective sequences, which allowed a total editing of the spectra. It was shown that deshielding of 13C mercurated sites occurred when the rate of mercuration increased. It was also possible to measure direct 1J(199Hg13C) coupling constants. The main bands of the vibrational spectra (infrared and Raman) were assigned. It was proved that v(C = O) and δ(C(γ)-H) could be directly related to the mercuration rate of molecules. 相似文献
9.
Imre Mezö János Seprödi Judit Érchegyi István Teplán Magdolna Kovacs Bela Flerkó 《Peptides》1983,4(2):149-151
Inhibitory analogues of luteinizing hormone-releasing hormone (LH-RH) were prepared with formyl-D-Trp1, acetyl-D-Trp1, valeryl-D-Trp1, tartaryl-D-Trp1, diacetyl-tartaryl-D-Trp1, acetyl-Gly1, and acetyl-Sar1 successively replacing the position one in the analogue [D-Trp1, D-p-Cl-Phe2, D-Trp3, D-Phe6, D-Ala10]-LH-RH. The formyl-D-Trp1 and acetyl-D-Trp1 analogues yielded 100% blockade of ovulation at the 10 μg dose; the others were less potent and inhibited ovulation at the 50 μg dose. The inhibitory potency seems to correlate with the polarity of the acyl group. 相似文献
10.
《Nucleosides, nucleotides & nucleic acids》2013,32(8-9):1523-1526
Resistance to, the hydrophilic drug ara‐C, might be meditated by decreased membrane transport. Lipophillic prodrugs were synthesized to facilitate uptake. These compounds were equally active as ara‐C, while the compounds with the shortest fatty‐acid group and highest number of double bonds were the more active. These compounds also show a better retention profile, their effect is retained longer than for ara‐C. 相似文献