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91.
Minerals such as titanium dioxide, TiO2, and zinc oxide, ZnO, are well known active semiconductor photocatalysts used extensively in heterogeneous photocatalysis to destroy environmental pollutants that are organic in nature. They are also extensively used in sunscreen lotions as active broadband sunscreens that screen both UVB (290-320 nm) and UVA (320-400 nm) sunlight radiation and as high SPF makers. When so photoactivated by UV light, however, these two particular metal oxides are known to generate highly oxidizing radicals (OH and ) and other reactive oxygen species (ROS) such as H2O2 and singlet oxygen, 1O2, which are known to be cytotoxic and/or genotoxic. Hydroxyl (OH) radicals photogenerated from photoactive TiO2 specimens extracted from commercial sunscreen lotions [R. Dunford, A. Salinaro, L. Cai, N. Serpone, S. Horikoshi, H. Hidaka, J. Knowland, FEBS Lett. 418 (1997) 87] induce damage to DNA plasmids in vitro and to whole human skin cells in cultures. Accordingly, the titanium dioxide particle surface was modified to produce TiO2 specimens of considerably reduced photoactivity. Deactivation of TiO2 diminishes considerably, in some cases completely suppresses damage caused to DNA plasmids, to human cells, and to yeast cells compared to non-modified specimens exposed to UVB/UVA simulated solar radiation. The photostabilities of sunscreen organic active agents in neat polar and apolar solvents and in actual commercial formulations have been examined [N. Serpone, A. Salinaro, A.V. Emeline, S. Horikoshi, H. Hidaka, J. Zhao, Photochem. Photobiol. Sci. 1 (2002) 970]. With rare exceptions, the active ingredients undergo photochemical changes (in some cases form free radicals) and the sunscreen lotions lose considerable Sun protection efficacy only after a relatively short time when exposed to simulated sunlight UVB/UVA radiation, confirming the recent findings by Sayre et al. [R.M. Sayre, J.C. Dowdy, A.J. Gerwig, W.J. Shields, R.V. Lloyd, Photochem. Photobiol. 81 (2005) 452]. 相似文献
92.
We demonstrate a novel DNA hybridization detection method with organic thin film transistors. DNA molecules are immobilized directly on the surface of organic semiconductors, producing an unambiguous doping-induced threshold voltage shift upon hybridization. With these shifts, single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) are differentiated successfully. This method is expected to result in higher sensitivity than the main competitive technology, ISFET-based sensors because of the direct exposure of DNA molecules to sensitive layers. Factors that influence sensor sensitivity have been analyzed and optimum conditions have been determined using statistically designed experiments. Under the optimum conditions, the maximum difference between saturation current ratios caused by ssDNA and dsDNA reaches as high as 70%. In order to make DNA detection fast, we also demonstrate rapid on-chip electrically enhanced hybridization using the TFTs. These technologies together will enable the realization of disposable, rapid-turnaround tools for field-deployable genomic diagnosis. 相似文献
93.
The luciferase secreted by the deep-sea shrimp Oplophorus consists of 19 and 35kDa proteins. The 19-kDa protein (19kOLase), the catalytic component of luminescence reaction, was expressed in Escherichia coli using the cold-shock inducted expression system. 19kOLase, expressed as inclusion bodies, was solubilized with 6M urea and purified by urea-nickel chelate affinity chromatography. The yield of 19kOLase was 16 mg from 400 ml of cultured cells. 19kOLase in 6M urea could be refolded rapidly by dilution with 50mM Tris-HCl (pH 7.8)-10mM EDTA, and the refolded protein showed luminescence activity. The luminescence properties of refolded 19kOLase were characterized, in comparison with native Oplophorus luciferase. Luminescence intensity with bisdeoxycoelenterazine as a substrate was stimulated in the presence of organic solvents. The 19kOLase is a thermolabile protein and is 98 % inhibited by 1muM Cu2+. The cysteine residue of 19kOLase is not essential for catalysis of the luminescence reaction. 相似文献
94.
A new organic solvent tolerant protease from <Emphasis Type="Italic">Bacillus pumilus</Emphasis> 115b 总被引:3,自引:0,他引:3
Rahman RN Mahamad S Salleh AB Basri M 《Journal of industrial microbiology & biotechnology》2007,34(7):509-517
Five out of the nine benzene–toulene–ethylbenzene-xylene (BTEX) tolerant bacteria that demonstrated high protease activity
on skim milk agar were isolated. Among them, isolate 115b identified as Bacillus pumilus exhibited the highest protease production. The protease produced was stable in 25% (v/v) benzene and toluene and it was activated
1.7 and 2.5- fold by n-dodecane and n-tetradecane, respectively. The gene encoding the organic solvent tolerant protease was cloned and its nucleotide sequence
determined. Sequence analysis revealed an open reading frame (ORF) of 1,149 bp that encoded a polypeptide of 383 amino acid
residues. The polypeptide composed of 29 residues of signal peptide, a propeptide of 79 residues and a mature protein of 275
amino acids with a calculated molecular mass of 27,846 Da. This is the only report available to date on organic solvent tolerant
protease from B. pumilus. 相似文献
95.
The effect of various organic solvents on the activity and stability of an extracellular protease produced by the haloalkaliphilic
archaeon Natrialba magadii was tested. This protease was active and stable in aqueous-organic solvent mixtures containing 1.5 M NaCl and glycerol, dimethylsulfoxide
(DMSO), N,N-dimethyl formamide, propylenglycol, and dioxane. Among the solvents tested, DMSO, propylenglycol, and glycerol were effective
in preserving enzyme stability in suboptimal NaCl concentrations. The stabilizing effect of DMSO on this haloalkaliphilic
protease was more efficient at pH 8 than at pH 10, suggesting that DMSO may not substitute for salt to allow halophilic proteins
to withstand the effect of high pH values. These results show that Nab. magadii extracellular protease is a solvent tolerant enzyme and suggest a potential application of this haloalkaliphilic protease
in aqueous-organic solvent biocatalysis. 相似文献
96.
Cereal-legume intercropping plays a vital role in the subsistence food production system that prevails in the arid regions. It not only provides profitable crop productivity for agricultural communities but also plays an important role in improving soil fertility. Therefore, the present research was conducted to assess the effect of the organic and mineral fertilizers on the forage yield and nutritional value in barley-pea intercropping system. The results revealed that the quality of forage grass is significantly influenced by both organic and inorganic fertilizer. Thus, organic fertilizer application has significantly influenced the dry matter (DM), crude ash (CA), crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF). Among the treatments, organic fertilizer added at rate of 35 m−3 ha−1 produced the maximum fresh and dry matter in barley and peas. In addition, the same level of organic fertilizer also improved silage composition by significantly increasing the protein and fiber content and showed highest the values. Based on overall results, it is concluded that organic fertilizer treatment (35 m−3 ha−1) has the potential as an effective strategy to improve the productivity and nutritional quality of the barley-pea intercropping system in arid areas. The results revealed that organic fertilizer can be utilized in sustainable agricultural as a source of nutrients for numerous various crops under arid conditions. 相似文献
97.
Polybrominated diphenyl ethers (PBDEs) are toxic contaminants with a persistent character and adverse effects on humans and wildlife. Therefore, the deposition of these chemicals in vegetation must be carefully controlled. Our objective was to determine PBDE concentrations (BDEs 28, 47, 66, 85, 99, 100, 153, 154, 183 and 209) in Pleurozium schreberi collected in a heavily industrialized urban agglomeration. High PBDE concentrations in the moss confirm the presence of active sources of atmospheric pollution in an area tested. The distribution of these xenobiotics was related to the vegetation cover being lower in sites surrounded by forests which indicates that PBDEs may have a tendency to be trapped from the air by tree leaves and needles. Congener profiles in P. schreberi were dominated by BDE 209 which was for 79% (in case of the coke smelter) to 95% (in case of the chemical plant) part of the total PBDE burden in this moss. The principal component and classification analysis classifying the concentration of PBDEs in P. schreberi allowed us to distinguish the pattern of these compounds characteristic for the origin of pollution. P. schreberi may be used as a bioindicator for PBDEs in areas contaminated with these chemicals. 相似文献
98.
Jan DickoppAuthor Vitae Marian KazdaAuthor VitaeHana ?í?kováAuthor Vitae 《Ecological Engineering》2011,37(11):1647-1653
Waterlogged soils are a challenging environment for plants due to anoxic conditions and enrichment of phytotoxic substances in the rhizosphere. High contents of organic matter in the substrate as present in constructed wetlands (CW) may amplify these effects. The influence of substrate organic matter on the rhizome aeration of Phragmites australis (common reed) was investigated in a CW for sewage treatment on two sites with different organic concentrations: (a) inflow part of the bed with a high organic charge (high-organic site) and (b) outflow zone of the bed with a lower organic charge (low-organic site). Several diurnal oxygen (O2) courses were recorded inside the rhizomes using micro-optodes. Maximum O2 percentages in the rhizomes were generally the same at both sites, but minimum O2 values were lower in the low-organic site than in the high-organic site, leading to higher amplitudes at the low-organic site. The results suggest that oxygen release from the roots is hampered under high-organic compared to low-organic conditions. This observation might be explained by changes in gas conductivity of the roots, but also by alterations in microbial oxygen demand, under different organic burden. 相似文献
99.
The effect of organic loading rate on foam initiation during mesophilic anaerobic digestion of municipal wastewater sludge 总被引:3,自引:0,他引:3
The impact of increasing organic load on anaerobic digestion foaming was studied at both full and bench scale. Organic loadings of 1.25, 2.5 and 5 kg VS m−3 were applied to bench-scale digesters. Foaming was monitored at a full scale digester operated in a comparable organic loading range over 15 months. The bench scale batch studies identified 2.5 kg VS m−3 as a critical threshold for foam initiation while 5 kg VS m−3 resulted in persistent foaming. Investigation of a full scale foaming event corroborated the laboratory observation that foaming may be initiated at a loading rate of ?2.5 kg VS m−3. Experimental findings on foam composition and differences in the quality characteristics between foaming and non-foaming sludges indicated that foam initiation derived from the combined effect of the liquid and gas phases inside a digester and that the solids/biomass ultimately stabilized foaming. 相似文献
100.
A modified Anaerobic Digestion Model No. 1 (ADM1), calibrated on a laboratory digester with a feeding mix of 30% weight of cow manure and 70% weight of corn silage, was implemented, showing its performances of simulation as a decision-making and planning-supporting tool for the anaerobic digestion of agricultural substrates. The virtual fermenter obtained was used to conduct simulations with different feeding compositions and loading rates of cow manure, corn silage, grass silage and rape oil. All simulations were started at the same initial state which was represented by a steady state with an organic loading rate of 2.5 kg ODM/(). The effects of the different feeding combinations on biogas composition and biogas yield were predicted reasonably, and partly verified with the available literature data. Results demonstrated that the simulations could be helpful for taking decisions on agricultural biogas plant operation or experimental set-ups, if used advisedly. 相似文献