168 research outputs found

    Сравнительная характеристика состава продуктов флэш-пиролиза фракций смол и асфальтенов усинской нефти

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    Узкие фракции смол и асфальтенов нефти Усинского месторождения (республика Коми), полученные дробным осаждением асфальтенов и хроматографическим разделением смол, охарактеризованы методами пиролитического анализа в варианте "Rock Eval" и флэш-пиролиза (650 °С, 20 с) с хроматомасс-спектрометрическим анализом летучих продуктов в режиме "on line". Показано, что изученные образцы содержат от 2,3 до 15,3 мас. % низкомолекулярных органических соединений. Продукты флэшпиролиза изученных образцов отличаются относительным содержанием таких типов соединений, как нормальные и изопреноидные алканы, ?-олефины, циклогексаны, хейлантаны и гопаны, гопены, прегнаны и стераны, алкилбензолы, нафталины, фенантрены и антрацены, бензо- и дибензотиофены, а также неидентифицированных коксообразующих фрагментов

    Probabilistic Analysis of Earthquake-Induced Pool Release

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    Wappapello Dam was constructed in 1938 near the New Madrid seismic region. Loose sands in the dam foundation led to concern for liquefaction and embankment sliding if a large earthquake were to occur. However it was also recognized that the operation of the dam for flood control results in relatively low reservoir levels the majority of the time, substantially reducing the risk of earthquake-induced flooding. Because of these factors, a probabilistic analysis was performed to assess the likelihood of the combination of required events leading to an earthquake-induced pool release. Results of such analyses provide better information on which to make both quantitative and qualitative judgements regarding remedial action

    Developing the Community reporting system for foodborne outbreaks.

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    Zonation of Central U. S. Earthquake Sources

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    A variety of analyses are utilized in developing potential earthquake ground shaking at a specific location. Geological procedures for estimating causes of earthquakes are fundamental to the prediction of ground motions. Evaluations of geologic factors compliment mathematical assessments of seismological data. Earthquake potential in the Central United States is predicted using the concept of seismic source zones due to the difficulty of determining active faults. Resolution of these geographic source zones is dependent upon knowledge of historic seismicity, pertinent geologic features, and causative tectonics. Regardless of the method used to delineate source zones, these zones must be geologically and seismologically unique. Statistical testing of historic earthquake catalogues is required for reduction of the data base. The resolution of zones is an iterative process of bounding the zones and determining recurrence rates. Earthquake potential and risk assessment should be understood by the owner and the designer of a facility

    Effect of Intraduodenal Bile and Na-Taurodeoxycholate on Exocrine Pancreatic Secretion and on Plasma Levels of Secretin, Pancreatic Polypeptide, and Gastrin in Man

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    The effect of intraduodenally administered cattle bile (CB) and Na-taurodeoxycholate (TDC) on basal pancreatic secretion and plasma levels of secretin, pancreatic polypeptide (PP), and gastrin were investigated on two separate days in 10 fasting volunteers. Doses of 2-6 g CB and 20&600 mg TDC were given intraduodenally at 65-min intervals. Volume, bicarbonate, lipase, trypsin, amylase, and bilirubin were measured in 10-min fractions of duodenal juice, and GI peptides determined by radioimmunoassay. CB and TDC enhanced significantly and dose-dependently volume, bicarbonate and enzyme secretion, and plasma secretin and PP levels. In contrast, plasma gastrin showed only a marginal increase. We conclude that the hydrokinetic effect of intraduodenal CB and TDC is at least partially mediated by secretin. Gastrin could be ruled out as a mediator of the ecbolic effect, whereas other GI peptides, primarily CCK, and/or neural mechanisms must be considered possible mediators. Both pathways may also play a role in the PP release

    Guidance on date marking and related food information: part 2 (food information)

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    A risk-based approach was used to develop guidance to be followed by food business operators (FBOs) when deciding on food information relating to storage conditions and/or time limits for consumption after opening a food package and thawing of frozen foods. After opening the package, contamination may occur, introducing new pathogens into the food and the intrinsic (e.g. pH and aw), extrinsic (e.g. temperature and gas atmosphere) and implicit (e.g. interactions with competing background microbiota) factors may change, affecting microbiological food safety. Setting a time limit for consumption after opening the package (secondary shelf-life) is complex in view of the many influencing factors and information gaps. A decision tree (DT) was developed to assist FBOs in deciding whether the time limit for consumption after opening, due to safety reasons, is potentially shorter than the initial ‘best before’ or ‘use by’ date of the product in its unopened package. For products where opening the package leads to a change of the type of pathogenic microorganisms present in the food and/or factors increasing their growth compared to the unopened product, a shorter time limit for consumption after opening would be appropriate. Freezing prevents the growth of pathogens, however, most pathogenic microorganisms may survive frozen storage, recover during thawing and then grow and/or produce toxins in the food, if conditions are favourable. Moreover, additional contamination may occur from hands, contact surfaces or contamination from other foods and utensils. Good practices for thawing should, from a food safety point of view, minimise growth of and contamination by pathogens between the food being thawed and other foods and/or contact surfaces, especially when removing the food from the package during thawing. Best practices for thawing foods are presented to support FBOs

    St. Louis Area Earthquake Hazards Mapping Project: Seismic and Liquefaction Hazard Maps

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    We present probabilistic and deterministic seismic and liquefaction hazard maps for the densely populated St. Louis metropolitan area that account for the expected effects of surficial geology on earthquake ground shaking. Hazard calculations were based on a map grid of 0.005°, or about every 500 m, and are thus higher in resolution than any earlier studies. To estimate ground motions at the surface of the model (e.g., site amplification), we used a new detailed near-surface shear-wave velocity model in a 1D equivalent- linear response analysis. When compared with the 2014 U.S. Geological Survey (USGS) National Seismic Hazard Model, which uses a uniform firm-rock-site condition, the new probabilistic seismic-hazard estimates document much more variability. Hazard levels for upland sites (consisting of bedrock and weathered bedrock overlain by loess-covered till and drift deposits), show up to twice the ground-motion values for peak ground acceleration (PGA), and similar ground-motion values for 1.0 s spectral acceleration (SA). Probabilistic ground-motion levels for lowland alluvial floodplain sites (generally the 20-40-m-thick modern Mississippi and Missouri River floodplain deposits overlying bedrock) exhibit up to twice the ground-motion levels for PGA, and up to three times the ground-motion levels for 1.0 s SA. Liquefaction probability curves were developed from available standard penetration test data assuming typical lowland and upland water table levels. A simplified liquefaction hazard map was created from the 5%-in-50-year probabilistic ground-shaking model. The liquefaction hazard ranges from low (\u3c40% of area expected to liquefy) in the uplands to severe (\u3e60% of area expected to liquefy) in the lowlands. Because many transportation routes, power and gas transmission lines, and population centers exist in or on the highly susceptible lowland alluvium, these areas in the St. Louis region are at significant potential risk from seismically induced liquefaction and associated ground deformation

    Update of the list of qualified presumption of safety (QPS) recommended microorganisms intentionally added to food or feed as notified to EFSA

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    The qualified presumption of safety (QPS) provides a generic pre-assessment of the safety ofmicroorganisms intended for use in the food or feed chains, to support the work of EFSA’s ScientificPanels. QPS assessment allows a fast track evaluation of strains belonging to QPS taxonomic units(TUs): species for bacteria, yeast, fungi, protists/microalgae and families for viruses. QPS TUs areassessed for their body of knowledge and safety. Safety concerns related to a QPS TU are reflected,when possible, as‘qualifications’, which should be tested at strain and/or product level. Based on thepossession of potentially harmful traits by some strains,filamentous fungi, bacteriophages, oomycetes,streptomycetes,Enterococcus faecium,Escherichia coliandClostridium butyricumare excluded fromthe QPS assessment.Between October 2019 and September 2022, 323 notifications of TUs werereceived, 217 related to feed additives, 54 to food enzymes, food additives andflavourings, 14 to plantprotection products and 38 to novel foods. The list of QPS-recommended TUs is reviewed every6 months following an extensive literature search strategy. Only sporadic infections with a few QPSstatus TUs in immunosuppressed individuals were identified and the assessment did not change theQPS status of these TUs. The QPS list has been updated in relation to the most recent taxonomicinsights and the qualifications were revised and streamlined. The qualification‘absence ofaminoglycoside production ability’was withdrawn forBacillus velezensis. Six new TUs received the QPSstatus:Bacillus paralicheniformiswith the qualification‘absence of toxigenic activity’and‘absence ofbacitracin production ability’;Bacillus circulanswith the qualifications for‘production purposes only’and‘absence of cytotoxic activity’;Haematococcus lacustris(synonymHaematococcus pluvialis) andOgataea polymorpha, both with the qualification‘for production purposes only’;Lactiplantibacillusargentoratensis;Geobacillus thermodenitrificanswith the qualification‘absence of toxigenic activity

    Update of the list of QPS-recommended biological agents intentionally added to food or feed as notified to EFSA 15: suitability of taxonomic units notified to EFSA until September 2021

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    The qualified presumption of safety (QPS) approach was developed to provide a generic pre-evaluation of the safety of biological agents. The QPS approach is based on an assessment of published data for each agent, with respect to its taxonomic identity, the body of relevant knowledge and safety concerns. Safety concerns are, where possible, confirmed at the species/strain or product level and reflected by ‘qualifications’. The QPS list was updated in relation to the revised taxonomy of the genus Bacillus, to synonyms of yeast species and for the qualifications ‘absence of resistance to antimycotics’ and ‘only for production purposes’. Lactobacillus cellobiosus has been reclassified as Limosilactobacillus fermentum. In the period covered by this statement, no new information was found that would change the status of previously recommended QPS taxonomic units (TU)s. Of the 70 microorganisms notified to EFSA, 64 were not evaluated: 11 filamentous fungi, one oomycete, one Clostridium butyricum, one Enterococcus faecium, five Escherichia coli, one Streptomyces sp., one Bacillus nakamurai and 43 TUs that already had a QPS status. Six notifications, corresponding to six TUs were evaluated: Paenibacillus lentus was reassessed because an update was requested for the current mandate. Enterococcus lactis synonym Enterococcus xinjiangensis, Aurantiochytrium mangrovei synonym Schizochytrium mangrovei, Schizochytrium aggregatum, Chlamydomonas reinhardtii synonym Chlamydomonas smithii and Haematococcus lacustris synonym Haematococcus pluvialis were assessed for the first time. The following TUs were not recommended for QPS status: P. lentus due to a limited body of knowledge, E. lactis synonym E. xinjiangensis due to potential safety concerns, A. mangrovei synonym S. mangrovei, S. aggregatum and C. reinhardtii synonym C. smithii, due to lack of a body of knowledge on its occurrence in the food and feed chain. H. lacustris synonym H. pluvialis is recommended for QPS status with the qualification ‘for production purposes only’

    Update of the list of QPS-recommended biological agents intentionally added to food or feed as notified to EFSA 12: suitability of taxonomic units notified to EFSA until March 2020

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    The qualified presumption of safety (QPS) was developed to provide a generic safety evaluation for biological agents to support EFSA's Scientific Panels. It is based on an assessment of the taxonomic identity, the body of knowledge, safety concerns and antimicrobial resistance. Safety concerns identified for a taxonomic unit (TU) are where possible to be confirmed at strain or product level, reflected by \u2018qualifications\u2019. No new information was found that would change the previously recommended QPS TUs of the 39 microorganisms notified to EFSA between October 2019 and March 2020, 33 were excluded, including five filamentous fungi, five Escherichia coli, two Enterococcus faecium, two Streptomyces spp. and 19 TUs already evaluated. Six TUs were evaluated. Akkermansia muciniphila was not recommended for QPS status due to safety concerns. Clostridium butyricum was not recommended because some strains contain pathogenicity factors. This TU was excluded for further QPS evaluation. Galdieria sulphuraria and Pseudomonas chlororaphis were also rejected due to a lack of body of knowledge. The QPS status of Corynebacterium ammoniagenes (with the qualification \u2018for production purposes only\u2019) and of Komagataella pastoris (with the qualification \u2018for enzyme production\u2019) was confirmed. In relation to the taxonomic revision of the Lactobacillus genus, previously designated Lactobacillus species will be reassigned to the new species and both the old and new names will be retained in the QPS list
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