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1.
Evaluation of stable isotope tracing for ZnO nanomaterials--new constraints from high precision isotope analyses and modeling 总被引:1,自引:0,他引:1
This contribution evaluates two possible routes of stable isotope tracing for ZnO nanomaterials. For this we carried out the first high precision Zn isotope analyses of commercially available ZnO nanomaterials, to investigate whether such materials exhibit isotope fractionations that can be exploited for tracing purposes. These measurements revealed Zn isotopic compositions (of δ(66/64)Zn = +0.28 to -0.31‰ relative to JMC Lyon Zn) that are indistinguishable from "normal" natural and anthropogenic Zn in environmental samples. Stable isotope tracing therefore requires the application of purpose-made isotopically enriched ZnO nanoparticles. A detailed evaluation identified the most suitable and cost-effective labeling isotopes for different analytical requirements and techniques. It is shown that, using relatively inexpensive (68)Zn for labeling, ZnO nanoparticles can be reliably detected in natural samples with a Zn background of 100 μg/g at concentrations as low as about 5 ng/g, if the isotopic tracing analyses are carried out by high precision mass spectrometry. Stable isotope tracing may also be able to differentiate between the uptake by organisms of particulate ZnO and Zn(2+) ions from the dissolution of nanoparticles. 相似文献
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We concentrate here on decomposition of 2D objects into meaningfulparts of visual form, orvisual parts. It is a simple observation that convex parts of objects determine visual parts. However, the problem is that many significant visual parts are not convex, since a visual part may have concavities. We solve this problem by identifying convex parts at different stages of a proposed contour evolution method in which significant visual parts will become convex object parts at higher stages of the evolution. We obtain a novel rule for decomposition of 2D objects into visual parts, called the hierarchical convexity rule, which states that visual parts are enclosed by maximal convex (with respect to the object) boundary arcs at different stages of the contour evolution. This rule determines not only parts of boundary curves but directly the visual parts of objects. Moreover, the stages of the evolution hierarchy induce a hierarchical structure of the visual parts. The more advanced the stage of contour evolution, the more significant is the shape contribution of the obtained visual parts. 相似文献
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Prof. Dr. Manfred Grote Dipl. Chem.-Ing. Didem Hanim Meriç Dr. Georg Langenkämper Dr. Heiko Hayen Dr. Thomas Betsche Prof. Dr. Mechthild Freitag 《Journal für Verbraucherschutz und Lebensmittelsicherheit》2009,4(3-4):287-304
Investigation on the transfer of pharmacologically active substances used in animal husbandry into leek and cabbage. The potential of leek and cabbage for uptake of highly prescribed veterinary drugs (antibiotics) was tested in hydroponically grown plants. For this purpose the antibiotics sulfadiazine (SFD), enrofloxacine (ENR), tetracycline (TC), chlortetracycline (CTC) and monensine (MON) were chosen. A further aim was to gain data on the situation of vegetables grown in agricultural practise with regard to antibiotic residues. The evident effects of the antibiotics on plants grown hydroponically (each antibiotic was administered at 5 μmol/l nutrient solution) were greatly different: With regard to leek there were no visible effects (MON, SFD), a weak bleaching of the younger leaf sections (CTC), and strong effects of ENR. The (phytotoxic) effects of antibiotics on cabbage were much more distinct. CTC caused a yellowing of the plant vasculature in cabbage. MON induced lesions on some leaves and finally led to leaf wilting. With administration of ENR a nearly complete bleaching of young leaves was observed. Using LC-MS/MS-methods (low-resolution and high-resolution MS) the administered antibiotics, as well as conversion products and metabolites, were separately identified and quantified in various organs of leek (roots, young and old sections of leaves) and cabbage (roots, stalks, young and old leaves). Depending on the type of antibiotic, vegetable species, and plant organ, the detected concentrations of antibiotic residues comprised several orders of magnitude ranging from μg/kg to mg/kg of fresh weight (fw). The highest concentrations of antibiotics were found in roots of both vegetable species: CTC and TC were detected at approximately 10 mg/kg fw in cabbage roots and at approximately 20 mg/kg fw in leek roots and ENR was determined at approximately 12 mg/kg fw in cabbage roots. Low amounts of ENR were metabolised to ciprofloxacine (CIP). ENR occurred at similar concentrations of approximately 7 mg/kg fw in roots and old leaves of cabbage, indicating a high transport rate of this antibiotic in the cabbage plant. In stalks, young and old leaves of cabbage and in young and old leaf sections of leek all administered antibiotics were detected. Within these antibiotics, ENR and CTC and their conversion products, e. g. demeclocycline (DMC) and TC, occurred at the highest concentrations. SFD and MON were found in considerably lower concentrations (<100 μg/kg fw). The results of our experiments in hydroponic cultures, using defined concentrations of antibiotics in the nutrient solution, evidently demonstrate that cabbage and leek have a very high potential for uptake of a number of veterinary antibiotic drugs, especially for tetracycline and ENR. 相似文献
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E. Westkämper 《CIRP Annals》2003,52(2):579-588
Industrial companies change the paradigms of business operations from optimisation of manufacturing processes to optimisation of products life cycles in order to activate the value of products, taking into account the potentials of product services in all phases of each product's life. From design to the end of their life capital intensive products, like manufacturing or assembly systems, are linked to a manufacturer network by global communication systems. This network allows special services even in the phases of usage and recycling. For this new paradigm it is necessary to develop strategies, methods and technologies to manage the business processes and the information and knowledge required in all phases of a product's life and to industrialise the processes of design, assembly, usage, service and remanufacturing by disassembly and recycling. It is the objective of this paper to define the processes for management of life cycle with a focus on assembly, service and disassembly of capital intensive products. 相似文献
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T. Tawakoli E. Westkmper M. Rabiey A. Rasifard 《International Journal of Machine Tools and Manufacture》2007,47(5):734-739
Oil and emulsion are two main grinding coolant lubricants (CLs) used in grinding processes with CBN tools. A comparison of these two CLs was performed as part of the long systematic research made by KSF. The comparison criteria presented in this paper are grinding forces and G-ratio. The results show that oil presents better function almost in every case for the selected grinding parameters and workpiece. However, it should be noted that the results could probably be different with other types of oil and emulsion. 相似文献
8.
W Hiddemann M Unterhalt R Herrmann HH W?ltjen ED Kreuser L Trümper M Reuss-Borst E Terhardt-Kasten M Busch A Neubauer U Kaiser RD Hanrath H Middeke G Helm M Freund H Stein M Tiemann R Parwaresch 《Canadian Metallurgical Quarterly》1998,16(5):1922-1930
PURPOSE: To compare mantle-cell lymphomas (MCLs) and follicle-center lymphomas (FCLs) for their features of clinical presentation, response to chemotherapy, and prognosis on the basis of a prospective randomized clinical trial. PATIENTS AND METHODS: Patients with MCL and FCL who entered onto the prospective randomized comparison of cyclophosphamide, vincristine, and prednisone (COP) versus prednimustine and mitoxantrone (PmM) followed by a second randomization for interferon (IFN) maintenance versus observation only. RESULTS: One hundred sixty-five of 234 patients had FCL and 45 of 234 patients had MCL. With FCL, both sexes were equally affected (men, 47%); patients with MCL were predominantly men (78%; P < .0004) and had a higher median age (64 v 53 years; P < .0001). Patients with MCL also had more widespread disease, reflected by the proportion of patients with two or greater extranodal manifestations (43% v 21%; P < .005) and nine or greater involved nodal areas (64% v 45%; nonsignificant [NS]). Response to chemotherapy was significantly lower in patients with MCL (complete remission [CR] + partial remission [PR], 69% v 88%; P < .05) and occurred at a slower pace. Patients with MCL also had a shorter event-free interval (median, 8 v 24 months; P < .0001) and overall survival (median, 28 v 77 months; P < .0001). In both subtypes, however, patients with less than two residual lymphoma manifestations in remission experienced a relatively good prognosis with an estimated 5-year survival of greater than 60% for MCL and greater than 75% for FCL. CONCLUSION: MCL and FCL differ substantially in their features of presentation, response to chemotherapy, and long-term prognosis. The extent of residual disease after completion of chemotherapy discriminates patients with different prognosis and may be used for the stratification of postremission strategies. 相似文献
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G Rehk?mper 《Canadian Metallurgical Quarterly》1997,81(2):171-192
It is argued that Darwin's concept of evolutionary change is primarily based on the idea of functional adaptation. Genealogical aspects are seen as a secondary consequence of this hypothesis. Unfortunately, the reception of Darwin's work was concentrated on the genealogical aspects from the very beginning (Huxley, Haeckel) and thus channeled future development of evolutionary morphology in a very one-sided way. This direction of development led to the adoption of cladism as a very sophisticated concept of comparative morphology. Though cladism claims to contribute to our understanding of evolution, it is demonstrated that it suffers in this regard because of the incompatibility of "pure morphology" with the demands of functional thinking as an integrative part of Darwin's proposition. 相似文献