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71.
Helga Tima Andrea Brückner Csilla Mohácsi-Farkas Gabriella Kiskó 《Food Additives and Contaminants: Part B: Surveillance Communications》2016,9(2):127-131
The Fusarium mycotoxins deoxynivalenol (DON), zearalenone (ZEN) and T-2 frequently contaminate grain crops in Middle and Eastern Europe. In this survey, 116 cereal samples (maize, wheat, barley and oat) were examined for DON, ZEN and T-2 mycotoxins. Samples were collected from different areas in two Hungarian regions (North and South Transdanubia). The method of analysis was indirect competitive ELISA. Maize was the most contaminated grain regarding DON (86%), ZEN (41%) and T-2 (55%) toxins. The average results of the deoxynivalenol and zearalenone tests of maize proved to be significantly higher than those of barley or oat. DON was the most represented Fusarium mycotoxin followed by T-2 and ZEN. The examination of these mycotoxins would be necessary at a larger scale as to re-evaluate permissible levels, so increase of the monitoring programme would be advisable for the future. 相似文献
72.
Williamson Richard A.; Bartels Helga; Murphy Gillian; Freedman Robert B. 《Protein engineering, design & selection : PEDS》1994,7(8):1035-1040
The truncated forms of tissue inhibitor of metalloproteinase-1and -2 (TIMP-1 and -2), comprising the N-terminal active domain,are ideal molecules for structural analysis by intrinsic fluorescenceas each contains a single conserved tryptophan residue. In thispaper we describe studies on their conformational stability,unfolding/refolding kinetics and the environment of the uniquetryptophan as judged by its fluorescence properties in the nativestate and exposure to an external quencher, acrylamide. Twoforms of TIMP-2 were studied: TIMP-2 T21 derived from the full-lengthcDNA clone isolated from a mixed-tumour library, and TIMP-2A21 containing the highly conserved V18IRAK22 sequence. In allthree TIMP proteins the tryptophan environments in the nativestate appeared to be similar, but substantial differences wereseen in their conformational stabilities and refolding kinetics.TIMP-1 was approximately twice as stable as TIMP-2 T21 and 1.4-foldmore stable than TIMP-2 A21. This stability difference betweenTIMP-1 and TIMP-2 was shown to be independent of N-linked glycosylation.TTMP-1 and TIMP-2 A21 both showed simple two-state refoldingkinetics, whereas TIMP-2 T21 refolding was more complex andbiphasic in character. These differences between TIMP-2 T21and A21 suggest that residue 21 is a structurally importantsite in the TIMP protein.All three truncated molecules can beconsidered as stable independent folding domains ideally suitedfor further structural analysis 相似文献
73.
Rescorla Leslie; Achenbach Thomas M.; Ivanova Masha Y.; Dumenci Levent; Almqvist Fredrik; Bilenberg Niels; Bird Hector; Broberg Anders; Dobrean Anca; D?pfner Manfred; Erol Nese; Forns Maria; Hannesdottir Helga; Kanbayashi Yasuko; Lambert Michael C.; Leung Patrick; Minaei Asghar; Mulatu Mesfin S.; Novik Torunn S.; Oh Kyung-Ja; Roussos Alexandra; Sawyer Michael; Simsek Zeynep; Steinhausen Hans-Christoph; Weintraub Sheila; Metzke Christa Winkler; Wolanczyk Tomasz; Zilber Nelly; Zukauskiene Rita; Verhulst Frank 《Canadian Metallurgical Quarterly》2007,75(2):351
In this study, the authors compared ratings of behavioral and emotional problems and positive qualities on the Youth Self-Report (T. M. Achenbach & L. A. Rescorla, 2001) by adolescents in general population samples from 24 countries (N = 27,206). For problem scales, country effect sizes (ESs) ranged from 3% to 9%, whereas those for gender and age ranged from less than 1% to 2%. Scores were significantly higher for girls than for boys on Internalizing Problems and significantly higher for boys than for girls on Externalizing Problems. Bicountry correlations for mean problem item scores averaged .69. For Total Problems, 17 of 24 countries scored within one standard deviation of the overall mean of 35.3. In the 19 countries for which parent ratings were also available, the mean of 20.5 for parent ratings was far lower than the self-report mean of 34.0 in the same 19 countries (d = 2.5). Results indicate considerable consistency across 24 countries in adolescents' self-reported problems but less consistency for positive qualities. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
74.
75.
The paper is devoted to the computation of shallow-water equations (or Euler equations) in using an approximate Godunov scheme called VFRoe, when the flow may include dry areas (or very low density regions). This is achieved with the help of symmetrizing variables. Overall we are able to insure the discrete preservation of positive variables on interfaces, and at the same time to compute vacuum occurence or propagation of shock waves over a near-vacuum. A short section is also dedicated to the non-conservative hyperbolic equations arising within the setting of one-equation or two-equation turbulent compressible models. Many numerical tests confirm the capabilities of the scheme, and measuring the L1 error norm in particular cases enables us to specify the actual rate of convergence. 相似文献
76.
The effect of oxygen partial pressure on the deposition rate, crystalline structure and optical absorption of thin film titanium suboxides prepared by the reactive sputtering of a titanium metal target is given. A wide variety of films ranging from metallic through semiconducting to dielectric specimens were deposited in a reproducible manner simply by controlling the oxygen content in the sputtering plasma atmosphere. In addition, polycrystalline stable semiconducting TiO2 electrodes were deposited onto heated glass substrates. The spectral response was investigated; a main absorption edge of about 410 nm was obtained. The design of a special substrate table with a unique mask changer that allowed for the fabrication of different geometrical film patterns is also given. 相似文献
77.
The design and operational parameters of a high-power pulser suitable for a photo-impulse ionized laser are presented. The relatively compact device utilizes a ceramic thyratron in a triggered resonant charging circuit. Efficient operation at repetition rates up to 40 kHz, with pulsed powers in excess of 2 MW and average powers of several kilowatts has been achieved. 相似文献
78.
A plethora of research makes it imperative for the scientist to know what has been done in his field and what is being done at present. To avoid duplication of efforts, he may also wish to get information on current grants and intramural projects. He may want to get in touch with fellow researchers whose interests coincide with his own. The Science Information Exchange (SIE) can supply him with this information. The SIE's unique mission is to make available information on current research either in the form of statistical data to agencies or through the investigator's own words, the summary which he has prepared for the Notice of Research Projects. The researcher is requested to omit confidential data, and the recipient of the summary is advised that he must not use the information for quotation or reference without the written permission of the principal investigator. The SIE maintains a professional and clerical staff to cope with the mammoth undertaking of storing and retrieving information on current research. The Exchange provides a valuable tool, but it is up to the scientific community to participate through registration and use, and thus insure maximum coverage of all fields of scientific endeavor. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
79.
We investigated the validity and sensitivity of assessments of the induction of atrazine tolerance in freshwater outdoor mesocosmic phytoplankton communities, using the in vivo fluorescence of chlorophyll a as an endpoint, for monitoring ecotoxicology and for risk assessment programs applied to phytoplankton contaminated by photosystem II herbicides. Atrazine inhibits the photosynthetic process, and so the rise in in-vivo fluorescence could be used as a physiological manifestation of acute toxicity. Short-term tests (1 h) were used, in which increasing concentrations of the herbicide were applied to phytoplankton samples taken every two days from the mesocosms, and used to plot dose-response curves. The concentration at which atrazine increased the fluorescence by 25% relative to control samples was used to demonstrate the sensitivity of the phytoplankton, and the values found were compared for samples from different mesocosms (contaminated and non-contaminated). The taxonomic composition of the phytoplankton was also determined. The data showed that chronic exposure (25 days) to 30 microg/L of atrazine significantly increased the apparent tolerance of the phytoplankton to further contamination by the same compound. The use of in vivo fluorescence of chlorophyll a appears to be a reliable and effective parameter for monitoring the effects of atrazine pollution, and detecting the changes in community tolerance driven by pollution selection pressure. 相似文献
80.
Helga Hornberger Hannah Kissel Birgit Striegl Matthias Kronseder Florian Vollnhals Silke Christiansen 《工业材料与腐蚀》2022,73(1):8-19
In the current research, magnesium and its alloys have been intensively studied as resorbable implant materials. Magnesium materials combine their good mechanical properties with bioactivity, which make them interesting for guided bone regeneration and for the application as barrier membranes. In this study, the in vitro degradation behavior of thin magnesium films was investigated in cell medium and simulated body fluid. Three methods were applied to evaluate corrosion rates: measurements of (i) the gaseous volume evolved during immersion, (ii) volume change after immersion, and (iii) polarization curves. In this comparison, measurements of H2 development in Dulbecco's modified Eagle's medium showed to be the most appropriate method, exhibiting a corrosion rate of 0.5 mm·year?1. Observed oxide and carbon contamination have a high impact on controlled degradation, suggesting that surface treatment of thin foils is necessary. The bioactivity test showed positive results; more detailed tests in this area are of interest. 相似文献