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41.
Dipl.-Geol. A. Musolff Dipl.-Hydrol. S. Leschik Dr. F. Reinstorf Dr. G. Strauch Prof. Dr. habil. M. Schirmer Dr. M. Möder 《Grundwasser》2007,12(3):217-231
Xenobiotics are increasingly being considered as ecotoxicologically relevant for the aquatic environment and human health. Their behaviour and the effects on the environment have not yet been comprehensively investigated and, therefore, are currently the subject of the project WASSER Leipzig initiated by the UFZ. The results of this article are based on groundwater and surface water analyses of a watershed within the town of Leipzig. Here the industrial chemicals bisphenol-A and t-nonylphenol, the polycyclic fragrances galaxolide and tonalide, the antiepileptic drug carbamacepine and caffeine where investigated. Xenobiotics showed ubiquitous occurrence in the rivers, which were contaminated from treated and untreated sewage, as well as in groundwater, contaminated by leaky sewers. Mean concentrations up to several hundred ng/l were found in the rivers, while groundwater concentrations, except for bisphenol-A, tended to be lower. Applying the statistical factor analysis on the hydrochemical measurements, a differentiation of the xenobiotics with regard to their hydrochemical behaviour in groundwater was performed. 相似文献
42.
M Lerm J Selzer A Hoffmeyer UR Rapp K Aktories G Schmidt 《Canadian Metallurgical Quarterly》1999,67(2):496-503
PURPOSE: To examine the relation between grating acuity at age 1 year and Snellen acuity and grating acuity at 5.5 years, in preterm children with birth weights less than 1251 g. METHODS: Subjects were participants in the multicenter study of Cryotherapy for Retinopathy of Prematurity. The Teller acuity card (TAC; Vistech Consultants, Dayton, OH) procedure was used to measure monocular grating acuity in children at ages 1 and 5.5 years. Early-treatment diabetic retinopathy study (ETDRS) charts were used to measure the childrens' monocular recognition (Snellen) acuity at age 5.5 years. Data are presented for 575 eyes with measurable TAC grating acuity at 1 year and 111 eyes that had no measurable acuity at 1 year. RESULTS: Among eyes with normal acuity at 1 year, 86.8% showed normal Snellen acuity, and 94.3% showed normal grating acuity at 5.5 years. Among eyes that were blind (i.e., had no measurable TAC grating acuity) at 1 year, 96.8% showed no quantifiable Snellen acuity, and 89.2% showed no quantifiable grating acuity at 5.5 years. Only 2.4% of eyes had acuity in the range between normal and blind at 1 year (i.e., measurable grating acuity <1.6 cyc/deg); thus, the predictive value of acuity scores in this range could not be determined. Correlation analysis indicated that the relative position within the normal range of an eye's grating acuity score at 1 year was not predictive of the relative position within the normal range of that eye's acuity score at 5.5 years. CONCLUSIONS: Among a large population of low-birth-weight infants, eyes with normal grating acuity at age 1 year generally showed normal Snellen and grating acuity at age 5.5 years, and eyes that had no quantifiable acuity at 1 year remained blind at 5.5 years. Relative position of an eye's acuity score within the normal range was not predictive of the relative position of that eye's later acuity score. 相似文献
43.
44.
The joint research project SAFIRA, which is supported by the Federal Ministry of Science and Education (BMBF), deals with the development of innovative technologies for the in situ remediation of heavily contaminated groundwater at the in situ pilot facility in Bitterfeld. In order to evaluate the new promising technological approaches comprehensively, methodological tools are developed to comparatively address economical, ecological as well as a environmental issues of related remediation scenarios. The design period for innovative technologies can hardly be forecasted and/or its success be guaranteed. To prove a long-term stability as well as to reach a sound economical and ecological evaluation for new approaches an on site operation over extended periods of time is needed. Therefore a variety of technologies are tested and optimized simultaneously, in order to achieve a thorough comparison of technologies at the end of the project. 相似文献
45.
Histamine is a pleiotropic mediator involved in a broad spectrum of (patho)-physiological processes, one of which is the regulation of inflammation. Compounds acting on three out of the four known histamine receptors are approved for clinical use. These approved compounds comprise histamine H1-receptor (H1R) antagonists, which are used to control allergic inflammation, antagonists at H2R, which therapeutically decrease gastric acid release, and an antagonist at H3R, which is indicated to treat narcolepsy. Ligands at H4R are still being tested pre-clinically and in clinical trials of inflammatory diseases, including rheumatoid arthritis, asthma, dermatitis, and psoriasis. These trials, however, documented only moderate beneficial effects of H4R ligands so far. Nevertheless, pre-clinically, H4R still is subject of ongoing research, analyzing various inflammatory, allergic, and autoimmune diseases. During inflammatory reactions in gut tissues, histamine concentrations rise in affected areas, indicating its possible biological effect. Indeed, in histamine-deficient mice experimentally induced inflammation of the gut is reduced in comparison to that in histamine-competent mice. However, antagonists at H1R, H2R, and H3R do not provide an effect on inflammation, supporting the idea that H4R is responsible for the histamine effects. In the present review, we discuss the involvement of histamine and H4R in inflammatory and inflammation-associated diseases of the gut. 相似文献
46.
The method of hierarchical imprinting was used for the first time in order to synthesize polymers with a high affinity for
nisin. The concept of this approach is demonstrated by filling the pores of silica particles, which contain immobilized peptidic
templates, with a mixture of monomers/initiator, followed by polymerization and subsequent dissolution of the silica template.
This method leaves imprinted polymers with binding sites located at the surface that are capable of recognizing larger molecules
with the same immobilized epitope. The results of the high-performance liquid chromatography analyses illustrate that the
highest retention factors and imprinting factors of nisin on nisin C-terminal analogously imprinted polymers could be obtained
with acetonitrile/water mixtures containing more than 80% water. Furthermore, nisin was strongly retained on polymers that
were imprinted with a longer amino acid sequence because of better sterical accessibility of the binding sites for the C terminus
of nisin. The retention of nisin (k = 21.65) under aqueous elution conditions results from selective ionic interactions and hydrophobic interactions. Furthermore,
the polymers exhibited selectivity for the template Lys-Ala and the structurally related dipeptide Ala-Lys. The results of
the present work show that these hierarchically imprinted polymers could be used for the chromatographic separation of the
polypeptide nisin in aqueous solutions. 相似文献
47.
M Knöbel FJ Busser A Rico-Rico NI Kramer JL Hermens C Hafner K Tanneberger K Schirmer S Scholz 《Environmental science & technology》2012,46(17):9690-9700
The zebrafish embryo toxicity test has been proposed as an alternative for the acute fish toxicity test, which is required by various regulations for environmental risk assessment of chemicals. We investigated the reliability of the embryo test by probing organic industrial chemicals with a wide range of physicochemical properties, toxicities, and modes of toxic action. Moreover, the relevance of using measured versus nominal (intended) exposure concentrations, inclusion of sublethal endpoints, and different exposure durations for the comparability with reported fish acute toxicity was explored. Our results confirm a very strong correlation of zebrafish embryo to fish acute toxicity. When toxicity values were calculated based on measured exposure concentrations, the slope of the type II regression line was 1 and nearly passed through the origin (1 to 1 correlation). Measured concentrations also explained several apparent outliers. Neither prolonged exposure (up to 120 h) nor consideration of sublethal effects led to a reduced number of outliers. Yet, two types of compounds were less lethal to embryos than to adult fish: a neurotoxic compound acting via sodium channels (permethrin) and a compound requiring metabolic activation (allyl alcohol). 相似文献
48.
Predicting concentrations of organic chemicals in fish by using toxicokinetic models 总被引:1,自引:0,他引:1
Quantification of chemical toxicity continues to be generally based on measured external concentrations. Yet, internal chemical concentrations have been suggested to be a more suitable parameter. To better understand the relationship between the external and internal concentrations of chemicals in fish, and to quantify internal concentrations, we compared three toxicokinetic (TK) models with each other and with literature data of measured concentrations of 39 chemicals. Two one-compartment models, together with the physiologically based toxicokinetic (PBTK) model, in which we improved the treatment of lipids, were used to predict concentrations of organic chemicals in two fish species: rainbow trout (Oncorhynchus mykiss) and fathead minnow (Pimephales promelas). All models predicted the measured internal concentrations in fish within 1 order of magnitude for at least 68% of the chemicals. Furthermore, the PBTK model outperformed the one-compartment models with respect to simulating chemical concentrations in the whole body (at least 88% of internal concentrations were predicted within 1 order of magnitude using the PBTK model). All the models can be used to predict concentrations in different fish species without additional experiments. However, further development of TK models is required for polar, ionizable, and easily biotransformed compounds. 相似文献
49.
Hering JG Hoehn E Klinke A Maurer M Peter A Reichert P Robinson C Schirmer K Schirmer M Stamm C Wehrli B 《Environmental science & technology》2012,46(1):112-118
Switzerland provides an example of successful management of water infrastructure and water resources that was accomplished largely without integration across sectors. Limitations in this approach have become apparent; decisions that were formerly based only on technical and economic feasibility must now incorporate broader objectives such as ecological impact. In addition, current and emerging challenges relate to increasingly complex problems that are likely to demand more integrated approaches. If such integration is to be of benefit, it must be possible to redirect resources across sectors, and the synergies derived from integration must outweigh the additional cost of increased complexity. 相似文献
50.
Lanthanum hexaaluminate—a new material for atmospheric plasma spraying of advanced thermal barrier coatings 总被引:1,自引:0,他引:1
One of the main application fields of the thermal spraying process is thermal barrier coatings (TBCs). Today, partially stabilized
zirconia (YSZ or MSZ) is mainly used as a TBC material. At temperatures above 1000 °C, zirconia layers age distinctively,
including phenomena shrinkage and microcrack formation. Therefore, there is a considerable interest in TBCs for higher temperature
applications. In this paper, lanthanum hexaaluminate, a newly developed TBC material with long-term stability up to 1400 °C,
is presented. It ages significantly more slowly at these high temperatures than commercial zirconia-based TBCs. Its composition
favors the formation of platelets, which prevent a densification of the coating by postsintering. It consists of La2O3, Al2O3, and MgO. Its crystal structure corresponds to a magnetoplumbite phase. Lanthanum hexaaluminate powders were produced using
two different fabrication routes, one based on salts and the other one based on oxides. To optimize the granulate, various
raw materials and additives were tested. The slurry was spray dried in a laboratory spray drier and calcined at 1650 °C. Using
these two powders, coatings were produced by atmospheric plasma spraying (APS). The residual stresses of the coatings were
measured by the hole drilling method, and the deposition process was optimized with respect to the residual stresses in the
TBC. The coatings were extensively analyzed regarding phase composition, thermal expansion, and long-term stability, as well
as microstructural properties. 相似文献