Science.gov

Sample records for iarc reevaluates silica

  1. The IARC monographs: critics and controversy.

    PubMed

    Samet, Jonathan M

    2015-07-01

    The monograph program of the International Agency for Research on Cancer (IARC), which relies on the efforts of volunteer Working Groups, uses a transparent approach to evaluate the carcinogenicity of agents for which scoping has determined that there is sufficient evidence to warrant a review. Because of the potentially powerful implications of the conclusions of the monographs and the sometimes challenging nature of the evidence reviewed, the monographs and the IARC process have been criticized from time to time. This commentary describes the IARC monograph process and addresses recent criticisms of the program, drawing on a recent defense of the program authored by 124 researchers. These authors concluded that the IARC processes are robust and transparent and not flawed and biased as suggested by some critics. PMID:25943987

  2. [IARC evaluations: how are they conducted and what suggestions are derived therefrom?].

    PubMed

    Piolatto, P G; Pira, E

    2007-01-01

    The IARC Monographs on the Evaluation of Carcinogenic Risks to Humans are considered by several Institutions a point of reference for the prevention of adverse effects (namely cancer) of occupational exposures. The conclusions which lead to the Classification of a substance or an industrial process are the results of a vote within a Working Group of experts and are expressed in terms of "evidence" based on both epidemiological and experimental data or "other relevant data". Several points are discussed which include the methods of identification of the experts, the criteria of evaluation of the available data, the meaning of some definitions and finally the impact of IARC conclusions and Classification on Public Health regulations and secondarily on compensation procedures or trial decisions. Three recent examples regarding the Classification of Free Crystalline Silica, Shift-Work and Vinyl Chloride Monomer, which cannot be accepted as such without some criticism, are reported. In conclusion the Authors appreciate the effort of the IARC to provide a source of information which "may assist national and international authorities in making risk assessments and in formulating decisions concerning any necessary preventive measures". However, they suggest that the IARC "overall evaluation" should not be taken as confidently as if no doubt at all would exist on the final statement and the consequent Classification. Some suggestions as to the solution of the question are also provided. PMID:18409257

  3. Man-made mineral (vitreous) fibres: evaluations of cancer hazards by the IARC Monographs Programme.

    PubMed

    Baan, Robert A; Grosse, Yann

    2004-09-01

    Man-made vitreous (glass-like) fibres are non-crystalline, fibrous inorganic substances (silicates) made primarily from rock, slag, glass or other processed minerals. These materials, also called man-made mineral fibres, include glass fibres (used in glass wool and continuous glass filament), rock or stone wool, slag wool and refractory ceramic fibres. They are widely used for thermal and acoustical insulation and to a lesser extent for other purposes. These products are potentially hazardous to human health because they release airborne respirable fibres during their production, use and removal. Man-made mineral fibres and man-made vitreous fibres have been the subject of reviews by IARC Monographs Working Groups in 1987 and 2001, respectively, which resulted in evaluations of the carcinogenic hazard to humans from exposure to these materials. These reviews and evaluations have been published as Volumes 43 and 81 of the IARC Monographs series [IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, vol. 43, Man-made Mineral Fibres and Radon (1988); IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, vol. 81, Man-made Vitreous Fibres (2002)]. The re-evaluation in 2001 was undertaken because there have been substantial improvements in the quality of the epidemiological information available on the carcinogenicity to humans of glass fibres, continuous glass filament and rock/slag wool. The new evaluations have addressed the limitations of earlier cohort studies, particularly concerning the lack of adjustment with respect to concomitant risk factors such as smoking and other sources of occupational exposure. In addition, the evaluation of the evidence for carcinogenicity of glass fibres to experimental animals has been refined, by making a distinction between insulation glass wool and special-purpose glass fibres. The results of the evaluations in 1987 and 2001 are thus different in several aspects. In this paper, the reviews and evaluations

  4. IARC Classification of Cell Phones as “Possible Carcinogen”

    Cancer.gov

    The World Health Organization’s International Agency for Research on Cancer (IARC) today classified mobile phone use and other radiofrequency electromagnetic fields as a possible carcinogen (group 2B). This is neither new research nor at odds with previous findings.

  5. IARC Monographs: 40 Years of Evaluating Carcinogenic Hazards to Humans

    PubMed Central

    Blair, Aaron; Vineis, Paolo; Ahrens, Wolfgang; Andersen, Aage; Anto, Josep M.; Armstrong, Bruce K.; Baccarelli, Andrea A.; Beland, Frederick A.; Berrington, Amy; Bertazzi, Pier Alberto; Birnbaum, Linda S.; Brownson, Ross C.; Bucher, John R.; Cantor, Kenneth P.; Cardis, Elisabeth; Cherrie, John W.; Christiani, David C.; Cocco, Pierluigi; Coggon, David; Comba, Pietro; Demers, Paul A.; Dement, John M.; Douwes, Jeroen; Eisen, Ellen A.; Engel, Lawrence S.; Fenske, Richard A.; Fleming, Lora E.; Fletcher, Tony; Fontham, Elizabeth; Forastiere, Francesco; Frentzel-Beyme, Rainer; Fritschi, Lin; Gerin, Michel; Goldberg, Marcel; Grandjean, Philippe; Grimsrud, Tom K.; Gustavsson, Per; Haines, Andy; Hartge, Patricia; Hansen, Johnni; Hauptmann, Michael; Heederik, Dick; Hemminki, Kari; Hemon, Denis; Hertz-Picciotto, Irva; Hoppin, Jane A.; Huff, James; Jarvholm, Bengt; Kang, Daehee; Karagas, Margaret R.; Kjaerheim, Kristina; Kjuus, Helge; Kogevinas, Manolis; Kriebel, David; Kristensen, Petter; Kromhout, Hans; Laden, Francine; Lebailly, Pierre; LeMasters, Grace; Lubin, Jay H.; Lynch, Charles F.; Lynge, Elsebeth; ‘t Mannetje, Andrea; McMichael, Anthony J.; McLaughlin, John R.; Marrett, Loraine; Martuzzi, Marco; Merchant, James A.; Merler, Enzo; Merletti, Franco; Miller, Anthony; Mirer, Franklin E.; Monson, Richard; Nordby, Karl-Cristian; Olshan, Andrew F.; Parent, Marie-Elise; Perera, Frederica P.; Perry, Melissa J.; Pesatori, Angela Cecilia; Pirastu, Roberta; Porta, Miquel; Pukkala, Eero; Rice, Carol; Richardson, David B.; Ritter, Leonard; Ritz, Beate; Ronckers, Cecile M.; Rushton, Lesley; Rusiecki, Jennifer A.; Rusyn, Ivan; Samet, Jonathan M.; Sandler, Dale P.; de Sanjose, Silvia; Schernhammer, Eva; Costantini, Adele Seniori; Seixas, Noah; Shy, Carl; Siemiatycki, Jack; Silverman, Debra T.; Simonato, Lorenzo; Smith, Allan H.; Smith, Martyn T.; Spinelli, John J.; Spitz, Margaret R.; Stallones, Lorann; Stayner, Leslie T.; Steenland, Kyle; Stenzel, Mark; Stewart, Bernard W.; Stewart, Patricia A.; Symanski, Elaine; Terracini, Benedetto; Tolbert, Paige E.; Vainio, Harri; Vena, John; Vermeulen, Roel; Victora, Cesar G.; Ward, Elizabeth M.; Weinberg, Clarice R.; Weisenburger, Dennis; Wesseling, Catharina; Weiderpass, Elisabete; Zahm, Shelia Hoar

    2015-01-01

    Background: Recently, the International Agency for Research on Cancer (IARC) Programme for the Evaluation of Carcinogenic Risks to Humans has been criticized for several of its evaluations, and also for the approach used to perform these evaluations. Some critics have claimed that failures of IARC Working Groups to recognize study weaknesses and biases of Working Group members have led to inappropriate classification of a number of agents as carcinogenic to humans. Objectives: The authors of this Commentary are scientists from various disciplines relevant to the identification and hazard evaluation of human carcinogens. We examined criticisms of the IARC classification process to determine the validity of these concerns. Here, we present the results of that examination, review the history of IARC evaluations, and describe how the IARC evaluations are performed. Discussion: We concluded that these recent criticisms are unconvincing. The procedures employed by IARC to assemble Working Groups of scientists from the various disciplines and the techniques followed to review the literature and perform hazard assessment of various agents provide a balanced evaluation and an appropriate indication of the weight of the evidence. Some disagreement by individual scientists to some evaluations is not evidence of process failure. The review process has been modified over time and will undoubtedly be altered in the future to improve the process. Any process can in theory be improved, and we would support continued review and improvement of the IARC processes. This does not mean, however, that the current procedures are flawed. Conclusions: The IARC Monographs have made, and continue to make, major contributions to the scientific underpinning for societal actions to improve the public’s health. Citation: Pearce N, Blair A, Vineis P, Ahrens W, Andersen A, Anto JM, Armstrong BK, Baccarelli AA, Beland FA, Berrington A, Bertazzi PA, Birnbaum LS, Brownson RC, Bucher JR, Cantor KP

  6. An IARC evaluation of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans as risk factors in human carcinogenesis.

    PubMed Central

    McGregor, D B; Partensky, C; Wilbourn, J; Rice, J M

    1998-01-01

    The International Agency for Research on Cancer (IARC) Monographs program reevaluated polychlorinated dibenzo-p-dioxins and evaluated polychlorinated dibenzofurans as possible carcinogenic hazards to humans in February 1997, using the most recent epidemiologic data on exposed human populations, experimental carcinogenicity bioassays in laboratory animals, and supporting evidence on relevant mechanisms of carcinogenesis. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) was evaluated as carcinogenic to humans (IARC group 1 classification) on the basis of limited evidence of carcinogenicity to humans derived from follow-up of workers who had been heavily exposed in industrial accidents and sufficient evidence of carcinogenicity in experimental animals. The evaluation also considered the following supporting evidence: TCDD is a multisite carcinogen in experimental animals and has been shown by several lines of evidence to act through a mechanism involving the aryl hydrocarbon receptor; this receptor is highly conserved in an evolutionary sense and functions the same way in humans as in experimental animals; tissue concentrations of TCDD are similar in heavily exposed human populations in which an increased overall cancer risk was observed and in exposed rats that developed tumors in carcinogenicity tests. Other polychlorinated dibenzo-p-dioxins, the nonchlorinated dibenzo-p-dioxin, and polychlorinated dibenzofurans were evaluated as not classifiable as to their carcinogenicity to humans (group 3). PMID:9599727

  7. Research Recommendations for Selected IARC-Classified Agents

    PubMed Central

    Ward, Elizabeth M.; Schulte, Paul A.; Straif, Kurt; Hopf, Nancy B.; Caldwell, Jane C.; Carreón, Tania; DeMarini, David M.; Fowler, Bruce A.; Goldstein, Bernard D.; Hemminki, Kari; Hines, Cynthia J.; Pursiainen, Kirsti Husgafvel; Kuempel, Eileen; Lewtas, Joellen; Lunn, Ruth M.; Lynge, Elsebeth; McElvenny, Damien M.; Muhle, Hartwig; Nakajima, Tamie; Robertson, Larry W.; Rothman, Nathaniel; Ruder, Avima M.; Schubauer-Berigan, Mary K.; Siemiatycki, Jack; Silverman, Debra; Smith, Martyn T.; Sorahan, Tom; Steenland, Kyle; Stevens, Richard G.; Vineis, Paolo; Zahm, Shelia Hoar; Zeise, Lauren; Cogliano, Vincent J.

    2010-01-01

    Objectives There are some common occupational agents and exposure circumstances for which evidence of carcinogenicity is substantial but not yet conclusive for humans. Our objectives were to identify research gaps and needs for 20 agents prioritized for review based on evidence of widespread human exposures and potential carcinogenicity in animals or humans. Data sources For each chemical agent (or category of agents), a systematic review was conducted of new data published since the most recent pertinent International Agency for Research on Cancer (IARC) Monograph meeting on that agent. Data extraction Reviewers were charged with identifying data gaps and general and specific approaches to address them, focusing on research that would be important in resolving classification uncertainties. An expert meeting brought reviewers together to discuss each agent and the identified data gaps and approaches. Data synthesis Several overarching issues were identified that pertained to multiple agents; these included the importance of recognizing that carcinogenic agents can act through multiple toxicity pathways and mechanisms, including epigenetic mechanisms, oxidative stress, and immuno- and hormonal modulation. Conclusions Studies in occupational populations provide important opportunities to understand the mechanisms through which exogenous agents cause cancer and intervene to prevent human exposure and/or prevent or detect cancer among those already exposed. Scientific developments are likely to increase the challenges and complexities of carcinogen testing and evaluation in the future, and epidemiologic studies will be particularly critical to inform carcinogen classification and risk assessment processes. PMID:20562050

  8. Carcinogenicity of the insulation wools: reassessment of the IARC evaluation.

    PubMed

    Brown, R C; Davis, J M; Douglas, D; Gruber, U F; Hoskins, J A; Ilgren, E B; Johnson, N F; Rossiter, C E; Wagner, J C

    1991-08-01

    In assessing the health evidence concerning man-made mineral fibers, the chemical composition, surface activity, durability, and size of fibers have to be taken into account. Special-purpose fine glass fibers need to be separated from the insulation wools (glass, rock, and slag wool). The epidemiological evidence is sufficient to conclude that there has been no mesothelioma risk to workers producing or using glass wool, rock wool, or slag wool. The epidemiological studies have been large and powerful, and they show no evidence of a cause-effect relationship between lung cancer and exposure to glass wool, rock wool, or slag wool fibers. There is some evidence of a small cancer hazard attached to the manufacturing process in slag wool plants 20 to 50 years ago, when asbestos was used in some products and other carcinogenic substances were present. However, this hazard is not associated with any index of exposure to slag wool itself. Animal inhalation studies of ordinary insulation wools also show that there is no evidence of hazard associated with exposure to these relatively coarse, soluble fibers. The evidence of carcinogenicity is limited to experiments with special-purpose fine durable glass fibers or experimental fibers, and only when these fibers are injected directly into the pleural or peritoneal cavity. Multiple chronic inhalation studies of these same special-purpose fine glass fibers have not produced evidence of carcinogenicity. It is suggested that the present IARC evaluation of the carcinogenic risk of insulation wools should be revised to Category 3: not classifiable as to carcinogenicity to humans. PMID:1947241

  9. Classification of man-made vitreous fibers: Comments on the revaluation by an IARC working group.

    PubMed

    Wardenbach, P; Rödelsperger, K; Roller, M; Muhle, H

    2005-11-01

    In 2001, an IARC working group revaluated the carcinogenic risks of man-made vitreous fibers (MMVF). Compared with the IARC evaluation in 1987, the overall evaluations of insulation glass wool, rock (stone) wool, and slag wool were changed from Group 2B to Group 3. These changes ensued from an alteration in the evidence for cancer in humans and in experimental animals: Instead of "sufficient," the evidence for cancer in experimental animals is now looked upon as "limited" if there is a carcinogenic response after intraperitoneal injection but not after recently conducted inhalation experiments. For these studies, it is argued that they did properly address the technological limitations of earlier inhalation experiments. For Maxim and McConnell [Maxim L.D., McConnell E.E., 2001. Interspecies comparisons of the toxicity of asbestos and synthetic vitreous fibers: a weight-of-the-evidence approach. Regul. Toxicol. Pharmacol. 33, 319-342], well-conducted inhalation studies are very sensitive and rats may be more sensitive than humans in detecting the carcinogenic potential of MMVF. However, their arguments are highly questionable. The explanations of the IARC working group for preferring the newer inhalation studies are not sufficiently supported by the published data. Having in mind the higher sensitivity of humans compared to rats after inhalation of asbestos, more emphasis should have been given to the carcinogenic response after intraperitoneal injection. PMID:16099571

  10. Reevaluation. Quick Turn Around (QTA).

    ERIC Educational Resources Information Center

    National Association of State Directors of Special Education, Alexandria, VA.

    This report discusses the results of a survey of 32 states and the Department of Defense Dependent Schools (DODDS) regarding the reevaluation of students who are classified as having a disability under the Individuals with Disabilities Education Act (IDEA). It summarizes provisions governing reevaluation in IDEA, describes the methodology of the…

  11. TP53 Variations in Human Cancers: New Lessons from the IARC TP53 Database and Genomics Data.

    PubMed

    Bouaoun, Liacine; Sonkin, Dmitriy; Ardin, Maude; Hollstein, Monica; Byrnes, Graham; Zavadil, Jiri; Olivier, Magali

    2016-09-01

    TP53 gene mutations are one of the most frequent somatic events in cancer. The IARC TP53 Database (http://p53.iarc.fr) is a popular resource that compiles occurrence and phenotype data on TP53 germline and somatic variations linked to human cancer. The deluge of data coming from cancer genomic studies generates new data on TP53 variations and attracts a growing number of database users for the interpretation of TP53 variants. Here, we present the current contents and functionalities of the IARC TP53 Database and perform a systematic analysis of TP53 somatic mutation data extracted from this database and from genomic data repositories. This analysis showed that IARC has more TP53 somatic mutation data than genomic repositories (29,000 vs. 4,000). However, the more complete screening achieved by genomic studies highlighted some overlooked facts about TP53 mutations, such as the presence of a significant number of mutations occurring outside the DNA-binding domain in specific cancer types. We also provide an update on TP53 inherited variants including the ones that should be considered as neutral frequent variations. We thus provide an update of current knowledge on TP53 variations in human cancer as well as inform users on the efficient use of the IARC TP53 Database. PMID:27328919

  12. Carcinogenic hazards from inhaled carbon black, titanium dioxide, and talc not containing asbestos or asbestiform fibers: recent evaluations by an IARC Monographs Working Group.

    PubMed

    Baan, Robert A

    2007-01-01

    In February 2006, an IARC Monographs Working Group reevaluated the carcinogenic hazards to humans of carbon black, titanium dioxide, and talc, which belong to the group of poorly soluble, low-toxicity particles. The review of the relevant literature and the evaluations by the Working Group will be published in Volume 93 of the IARC Monographs series. This article summarizes the Working Group's conclusions. Epidemiological studies among workers in carbon black production and in the rubber industry provided inadequate evidence of carcinogenicity. The overall data from cancer studies in rodents exposed to carbon black provided sufficient evidence of carcinogenicity. The Working Group evaluated carbon black as possibly carcinogenic to humans, Group 2B. Reviewing the epidemiological studies in the titanium dioxide production industry, the Working Group concluded that there is inadequate evidence of carcinogenicity. Overall, the results from rodent cancer studies with titanium dioxide were considered to provide sufficient evidence. Titanium dioxide was evaluated as possibly carcinogenic to humans, Group 2B. Epidemiological studies on talc miners and millers provided inadequate evidence of carcinogenicity of inhaled talc not containing asbestos or asbestiform fibers. The evidence from rodent cancer studies was considered limited. The Working Group evaluated inhaled talc not containing asbestos or asbestiform fibers as not classifiable as to its carcinogenicity to humans, Group 3. The Working Group noted that prolonged exposure to inhaled particles at sufficiently high concentrations in experimental animals may lead to impairment of normal clearance mechanisms in the alveolar region of the lung, resulting in a continued buildup of particles that eventually leads to excessive lung burdens accompanied by chronic alveolar inflammation. The inflammatory response may give rise to increased generation of reactive oxygen species, cell injury, cell proliferation, fibrosis

  13. Use of mechanistic data in the IARC evaluations of the carcinogenicity of polychlorinated biphenyls and related compounds.

    PubMed

    Lauby-Secretan, Béatrice; Loomis, Dana; Baan, Robert; El Ghissassi, Fatiha; Bouvard, Véronique; Benbrahim-Tallaa, Lamia; Guha, Neela; Grosse, Yann; Straif, Kurt

    2016-02-01

    The IARC Monographs are a series of scientific reviews that identify environmental factors that can increase the risk of cancer in humans. In its first part, the principles and procedures of the IARC Monographs evaluations are summarized. In a second part, we present the most recent IARC evaluation of polychlorinated biphenyls (PCBs) and polybrominated biphenyls (PBBs), performed in February 2013: PCBs and dioxin-like PCBs were both classified into group 1 "carcinogens," while PBBs were evaluated as "probably carcinogenic to humans" (group 2A). Noteworthy is that the relative contributions of different PCB congeners to the carcinogenicity of PCB mixtures are not known. The use of mechanistic data for the classification into a higher category is discussed in the context of the history of the consecutive evaluations of several related polychlorinated compounds. PMID:26077316

  14. Meeting Report: Summary of IARC Monographs on Formaldehyde, 2-Butoxyethanol, and 1-tert-Butoxy-2-Propanol

    PubMed Central

    Cogliano, Vincent James; Grosse, Yann; Baan, Robert A.; Straif, Kurt; Secretan, Marie Béatrice; Ghissassi, Fatiha El

    2005-01-01

    An international, interdisciplinary working group of expert scientists met in June 2004 to develop IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans (IARC Monographs) on formaldehyde, 2-butoxyethanol, and 1-tert-butoxy-2-propanol. Each IARC Monograph includes a critical review of the pertinent scientific literature and an evaluation of an agent’s potential to cause cancer in humans. After a thorough discussion of the epidemiologic, experimental, and other relevant data, the working group concluded that formaldehyde is carcinogenic to humans, based on sufficient evidence in humans and in experimental animals. In the epidemiologic studies, there was sufficient evidence that formaldehyde causes nasopharyngeal cancer, “strong but not sufficient” evidence of leukemia, and limited evidence of sinonasal cancer. The working group also concluded that 2-butoxyethanol and 1-tert-butoxy-2-propanol are not classifiable as to their carcinogenicity to humans, each having limited evidence in experimental animals and inadequate evidence in humans. These three evaluations and the supporting data will be-published as Volume 88 of the IARC Monographs. PMID:16140628

  15. Considerations of circadian impact for defining 'shift work' in cancer studies: IARC Working Group Report.

    PubMed

    Stevens, Richard G; Hansen, Johnni; Costa, Giovanni; Haus, Erhard; Kauppinen, Timo; Aronson, Kristan J; Castaño-Vinyals, Gemma; Davis, Scott; Frings-Dresen, Monique H W; Fritschi, Lin; Kogevinas, Manolis; Kogi, Kazutaka; Lie, Jenny-Anne; Lowden, Arne; Peplonska, Beata; Pesch, Beate; Pukkala, Eero; Schernhammer, Eva; Travis, Ruth C; Vermeulen, Roel; Zheng, Tongzhang; Cogliano, Vincent; Straif, Kurt

    2011-02-01

    Based on the idea that electric light at night might account for a portion of the high and rising risk of breast cancer worldwide, it was predicted long ago that women working a non-day shift would be at higher risk compared with day-working women. This hypothesis has been extended more recently to prostate cancer. On the basis of limited human evidence and sufficient evidence in experimental animals, in 2007 the International Agency for Research on Cancer (IARC) classified 'shift work that involves circadian disruption' as a probable human carcinogen, group 2A. A limitation of the epidemiological studies carried out to date is in the definition of 'shift work.' IARC convened a workshop in April 2009 to consider how 'shift work' should be assessed and what domains of occupational history need to be quantified for more valid studies of shift work and cancer in the future. The working group identified several major domains of non-day shifts and shift schedules that should be captured in future studies: (1) shift system (start time of shift, number of hours per day, rotating or permanent, speed and direction of a rotating system, regular or irregular); (2) years on a particular non-day shift schedule (and cumulative exposure to the shift system over the subject's working life); and (3) shift intensity (time off between successive work days on the shift schedule). The group also recognised that for further domains to be identified, more research needs to be conducted on the impact of various shift schedules and routines on physiological and circadian rhythms of workers in real-world environments. PMID:20962033

  16. Comparison between carcinogenicity and mutagenicity based on chemicals evaluated in the IARC monographs.

    PubMed Central

    Bartsch, H; Tomatis, L

    1983-01-01

    The qualitative relationship between carcinogenicity and mutagenicity (DNA-damaging activity), based on chemicals which are known to be or suspected of being carcinogenic to man and/or to experimental animals, is analyzed using 532 chemicals evaluated in Volumes 1-25 of the IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. About 40 compounds (industrial processes) were found to be either definitely or probably carcinogenic to man, and 130 chemicals have been adequately tested in rodents and most of them also in various short-term assays. For a comparison between the carcinogenicity of a chemical and its behavior in short-term tests, systems were selected that have a value for predicting carcinogenicity. These were divided into mutagenicity in (A) the S. typhimurium/microsome assay, (B) other submammalian systems and (C) cultured mammalian cells; (D) chromosomal abnormalities in mammalian cells; (E) DNA damage and repair; (F) cell transformation (or altered growth properties) in vitro. The following conclusions can be drawn. In the absence of studies in man, long-term animal tests are still today the only ones capable of providing evidence of the carcinogenic effect of a chemical. The development and application of an appropriate combination of short-term tests (despite current limitations) can significantly contribute to the prediction/confirmation of the carcinogenic effects of chemicals in animals/man. Confidence in positive tests results is increased when they are confirmed in multiple short-term tests using nonrepetitive end points and different activation systems. Assays to detect carcinogens which do not act via electrophiles (promoters) need to be developed. The results of a given short-term test should be interpreted in the context of other toxicological data. Increasing demand for quantitative carcinogenicity data requires further examination of whether or not there is a quantitative relationship between the potency of a

  17. The International Agency for Research on Cancer (IARC) evaluation of the carcinogenicity of outdoor air pollution: focus on China

    PubMed Central

    Loomis, Dana; Huang, Wei; Chen, Guosheng

    2014-01-01

    The International Agency for Research on Cancer (IARC) has classified outdoor air pollution and the particulate matter (PM) in outdoor air pollution as carcinogenic to humans, as based on sufficient evidence of carcinogenicity in humans and experimental animals and strong support by mechanistic studies. The data with important contributions to the evaluation are reviewed, highlighting the data with particular relevance to China, and implications of the evaluation with respect to China are discussed. The air pollution levels in Chinese cities are among the highest observed in the world today and frequently exceed health-based national and international guidelines. Data from high-quality epidemiologic studies in Asia, Europe, and North America consistently show positive associations between lung cancer and PM exposure and other indicators of air pollution, which persist after adjustment for important lung cancer risk factors, such as tobacco smoking. Epidemiologic data from China are limited but nevertheless indicate an increased risk of lung cancer associated with several air pollutants. Excess cancer risk is also observed in experimental animals exposed to polluted outdoor air or extracted PM. The exposure of several species to outdoor air pollution is associated with markers of genetic damage that have been linked to increased cancer risk in humans. Numerous studies from China, especially genetic biomarker studies in exposed populations, support that the polluted air in China is genotoxic and carcinogenic to humans. The evaluation by IARC indicates both the need for further research into the cancer risks associated with exposure to air pollution in China and the urgent need to act to reduce exposure to the population. PMID:24694836

  18. 77 FR 59675 - Compliance With Information Request, Flooding Hazard Reevaluation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-28

    ... COMMISSION Compliance With Information Request, Flooding Hazard Reevaluation AGENCY: Nuclear Regulatory... was needed in the areas of seismic and flooding design, and emergency preparedness. In addition to... licensees reevaluate flooding hazards at nuclear power plant sites using updated flooding hazard...

  19. 34 CFR 300.303 - Reevaluations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 2 2010-07-01 2010-07-01 false Reevaluations. 300.303 Section 300.303 Education Regulations of the Offices of the Department of Education (Continued) OFFICE OF SPECIAL EDUCATION AND REHABILITATIVE SERVICES, DEPARTMENT OF EDUCATION ASSISTANCE TO STATES FOR THE EDUCATION OF CHILDREN WITH DISABILITIES Evaluations,...

  20. 14 CFR 161.409 - Required analysis by reevaluation petitioner.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Required analysis by reevaluation... Stage 3 Restrictions § 161.409 Required analysis by reevaluation petitioner. (a) An aircraft operator that has petitioned the FAA to reevaluate a restriction shall assume the burden of analysis for...

  1. Silica nephropathy.

    PubMed

    Ghahramani, N

    2010-07-01

    Occupational exposure to heavy metals, organic solvents and silica is associated with a variety of renal manifestations. Improved understanding of occupational renal disease provides insight into environmental renal disease, improving knowledge of disease pathogenesis. Silica (SiO2) is an abundant mineral found in sand, rock, and soil. Workers exposed to silica include sandblasters, miners, quarry workers, masons, ceramic workers and glass manufacturers. New cases of silicosis per year have been estimated in the US to be 3600-7300. Exposure to silica has been associated with tubulointerstitial disease, immune-mediated multisystem disease, chronic kidney disease and end-stage renal disease. A rare syndrome of painful, nodular skin lesions has been described in dialysis patients with excessive levels of silicon. Balkan endemic nephropathy is postulated to be due to chronic intoxication with drinking water polluted by silicates released during soil erosion. The mechanism of silica nephrotoxicity is thought to be through direct nephrotoxicity, as well as silica-induced autoimmune diseases such as scleroderma and systemic lupus erythematosus. The renal histopathology varies from focal to crescentic and necrotizing glomerulonephritis with aneurysm formation suggestive of polyarteritis nodosa. The treatment for silica nephrotoxicity is non-specific and depends on the mechanism and stage of the disease. It is quite clear that further research is needed, particularly to elucidate the pathogenesis of silica nephropathy. Considering the importance of diagnosing exposure-related renal disease at early stages, it is imperative to obtain a thorough occupational history in all patients with renal disease, with particular emphasis on exposure to silica, heavy metals, and solvents. PMID:23022796

  2. Does the crystal habit modulate the genotoxic potential of silica particles? A cytogenetic evaluation in human and murine cell lines.

    PubMed

    Guidi, P; Nigro, M; Bernardeschi, M; Lucchesi, P; Scarcelli, V; Frenzilli, G

    2015-10-01

    Crystalline silica inhaled from occupational sources has been classified by IARC as carcinogenic to humans; in contrast, for amorphous silica, epidemiological and experimental evidence remains insufficient. The genotoxicity of crystalline silica is still debated because of the inconsistency of experimental results ("variability of silica hazard"), often related to the features of the particle surfaces. We have assessed the role of crystal habit in the genotoxicity of silica powders. Pure quartz (crystalline) and vitreous silica (amorphous), sharing the same surface features, were used in an in vitro study with human pulmonary epithelial (A549) and murine macrophage (RAW264.7) cell lines, representative of occupational and environmental exposures. Genotoxicity was evaluated by the comet and micronucleus assays, and cytotoxicity by the trypan blue method. Cells were treated with silica powders for 4 and 24h. Quartz but not vitreous silica caused cell death and DNA damage in RAW264.7 cells. A549 cells were relatively resistant to both powders. Our results support the view that crystal habit per se plays a pivotal role in modulating the biological responses to silica particles. PMID:26433261

  3. The Need to Reevaluate Nonresponding Ergonomic Patients

    NASA Technical Reports Server (NTRS)

    Scarpa, Philip J.; Field, Steven A.

    1999-01-01

    The Kennedy Space Center (KSC) Environmental Health (EH) contractor performs ergonomic evaluations under its Ergonomic Program. Any KSC employee may request one or the reviewing physician may request one for a patient during a visit to an onsite medical facility. As part of the ergonomic evaluation, recommendations are given to the patient to help reduce any ergonomic problems they experience. The recommendations, if implemented, are successful in the majority of KSC patients; however, a group of patients do not seem to improve. Those who don't improve may be identified by reevaluations, which are performed to implement maximum resolution of ergonomic problems.

  4. Site characterization plan thermal goals reevaluation

    SciTech Connect

    Saterlie, S.F.; Garza, J.C. de la

    1994-12-31

    Because performance standards are not established for the Yucca Mountain Site (the Environmental Protection Agency (EPA) standards have been remanded), it is necessary to define surrogate or derived criteria to evaluate performance. The Site Characterization Plan (SCP) in 1988 attempted to define surrogate criteria that could be used to establish repository performance. Since that time, new knowledge has become available and some additional analyses of thermal loading have been performed. Thus it became clear that the thermal goals established in the SCP should be reevaluated. This paper reports on a two month effort undertaken to reevaluate the SCP thermal goals using an expert Working Group. Fifteen thermal goals identified in various sections of the SCP were evaluated by the Working Group. It was recommended that two goals be deleted: (1) to keep borehole wall temperature < 275 degrees C and keep the mid-drift temperature < 100 degrees C. It was also recommended that one goal be added to establish a thermal loading that would not degrade the Upper Paintbrush Tuff Formation (Lowermost Tiva Canyon; Yucca Mountain; Pah Canyon; and Uppermost Topopah Spring Members) (Vitric nonwelded) (PTn) barrier. Two other thermal goals and a process statement were reworded to afford compatibility with any emplacement mode, not just the vertical borehole. A recommendation was made to increase the conservatism of a goal to limit potential impact on the surface environment by limiting temperature rise to < 2 degrees C rather than < 6 degrees C. This revised set of goals was used in the Thermal Loading Systems Study.

  5. 23 CFR 771.129 - Re-evaluations.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 23 Highways 1 2011-04-01 2011-04-01 false Re-evaluations. 771.129 Section 771.129 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RIGHT-OF-WAY AND ENVIRONMENT ENVIRONMENTAL IMPACT AND RELATED PROCEDURES § 771.129 Re-evaluations. (a) A written evaluation of the draft EIS shall be...

  6. 23 CFR 771.129 - Re-evaluations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 23 Highways 1 2010-04-01 2010-04-01 false Re-evaluations. 771.129 Section 771.129 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RIGHT-OF-WAY AND ENVIRONMENT ENVIRONMENTAL IMPACT AND RELATED PROCEDURES § 771.129 Re-evaluations. (a) A written evaluation of the draft EIS shall be...

  7. In vitro comet and micronucleus assays do not predict morphological transforming effects of silica particles in Syrian Hamster Embryo cells.

    PubMed

    Darne, Christian; Coulais, Catherine; Terzetti, Francine; Fontana, Caroline; Binet, Stéphane; Gaté, Laurent; Guichard, Yves

    2016-01-15

    Crystalline silica particles and asbestos have both been classified as carcinogenic by the International Agency for Research on Cancer (IARC). However, because of the limited data available, amorphous silica was not classifiable. In vitro, the carcinogenic potential of natural crystalline and amorphous silica particles has been revealed by the Syrian Hamster Embryo (SHE) cell transformation assay. On the other hand, the genotoxic potential of those substances has not been investigated in SHE cells. And yet, genotoxicity assays are commonly used for hazard evaluation and they are often used as in vitro assays of reference to predict a possible carcinogenic potential. The main objective of this study was to compare the genotoxic potential and the carcinogenic potential of different crystalline and amorphous silica particles in SHE cells. Three silica samples of different crystallinity were used: natural amorphous silica, partially crystallized silica and quartz silica particles. Their genotoxicity were tested through the in vitro micronucleus assay and the comet assay in SHE, and their carcinogenic potential through the SHE transformation assay. In addition, silica samples were also tested with the same genotoxicity assays in V79 hamster-lung cells, a common in vitro model for particle exposure. Results obtained in the micronucleus and the comet assays show that none of the silica was capable of inducing genotoxic effects in SHE cells and only the amorphous silica induced genotoxic effects in V79 cells. However in the SHE cell transformation assays, the partially crystallized and quartz silica were able to induce morphological cell transformation. Together, these data suggest that, in vitro, the short-term genotoxic assays alone are not sufficient to predict the hazard and the carcinogenic potential of this type of particles; SHE transformation assay appears a more reliable tool for this purpose and should be included in the "in vitro battery assays" for hazard

  8. The personal myth: a re-evaluation.

    PubMed

    Sirois, François

    2014-04-01

    This paper presents a re-evaluation of Kris's personal myth. The notion has been used rather sparingly despite the Delphi Symposium in 1984 on the question of its clinical usefulness. After framing the notion of myth, some difficulties related to the question are identified. A clinical vignette exemplifies some of the ambiguities in its definition but stresses its clinical relevance. A discussion expands on these situations so as to propose three various aspects of personal myths to account for the two variants identified by Kris. The actualization of the underlying fantasy in the character organization is a third form and the technical aspect associated with it is reviewed from a new perspective. The family romance is revisited to reassess its role as the basis of the personal myth in the face of studies favouring an earlier development of the myth. PMID:24580376

  9. Site characterization plan thermal goals reevaluation

    SciTech Connect

    1993-09-08

    The Site Characterization Plan (SCP) (DOE, 1988) attempted to define surrogate criteria that could be used to establish potential repository performance. These criteria or SCP thermal goals were developed from knowledge existing at the time and, as a reference case, emphasized performance for waste emplacement in a vertical borehole. Since that time, new knowledge has become available and some additional analyses of thermal loading have been performed. Additionally, other emplacement modes such as in-drift emplacement are being considered to accommodate larger waste packages. New concepts such as ``extended hot`` are also being considered as possible methods to achieve improved waste isolation. Thus it became clear that the thermal goals established in the SCP should be reevaluated. A Working Group was formed to reassess the SCP thermal goals to determine whether each goal was still valid, if there were goals that needed to be added, and what if any effort was needed to reduce the uncertainty associated with a particular goal. The objectives of the effort were to: (1) provide thermal goals that would support the FY 1993 Thermal Loading Systems Study; (2) help focus the planned testing and analysis efforts; and (3) acquire data that potentially could be used to initiate a change to the project technical baseline. Sixteen thermal goals were evaluated; fifteen were from various sections of the SCP; one goal was added, and another was split into two to include in-drift emplacement. The group`s findings and recommendations are presented.

  10. Reevaluation of compressible-flow Preston tube calibrations

    NASA Technical Reports Server (NTRS)

    Allen, J. M.

    1977-01-01

    Revised zero-pressure-gradient, adiabatic wall skin-friction-balance data covering a Mach number range from 1.6 to 4.6 led to a reevaluation of existing compressible flow Preston tube calibration equations.

  11. 14 CFR 161.407 - Notice of reevaluation.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...) AIRPORTS NOTICE AND APPROVAL OF AIRPORT NOISE AND ACCESS RESTRICTIONS Reevaluation of Stage 3 Restrictions..., operators of aircraft based at the airport, potential new entrants that are known to be interested...

  12. Reevaluation of erythropoietin production by the nephron.

    PubMed

    Nagai, Takanori; Yasuoka, Yukiko; Izumi, Yuichiro; Horikawa, Kahori; Kimura, Miho; Nakayama, Yushi; Uematsu, Takayuki; Fukuyama, Takashi; Yamazaki, Taiga; Kohda, Yukimasa; Hasuike, Yukiko; Nanami, Masayoshi; Kuragano, Takahiro; Kobayashi, Noritada; Obinata, Masuo; Tomita, Kimio; Tanoue, Akito; Nakanishi, Takeshi; Kawahara, Katsumasa; Nonoguchi, Hiroshi

    2014-06-27

    Erythropoietin production has been reported to occur in the peritubular interstitial fibroblasts in the kidney. Since the erythropoietin production in the nephron is controversial, we reevaluated the erythropoietin production in the kidney. We examined mRNA expressions of erythropoietin and HIF PHD2 using high-sensitive in situ hybridization system (ISH) and protein expression of HIF PHD2 using immunohistochemistry in the kidney. We further investigated the mechanism of erythropoietin production by hypoxia in vitro using human liver hepatocell (HepG2) and rat intercalated cell line (IN-IC cells). ISH in mice showed mRNA expression of erythropoietin in proximal convoluted tubules (PCTs), distal convoluted tubules (DCTs) and cortical collecting ducts (CCDs) but not in the peritubular cells under normal conditions. Hypoxia induced mRNA expression of erythropoietin largely in peritubular cells and slightly in PCTs, DCTs, and CCDs. Double staining with AQP3 or AE1 indicated that erythropoietin mRNA expresses mainly in β-intercalated or non α/non β-intercalated cells of the collecting ducts. Immunohistochemistry in rat showed the expression of HIF PHD2 in the collecting ducts and peritubular cells and its increase by anemia in peritubular cells. In IN-IC cells, hypoxia increased mRNA expression of erythropoietin, erythropoietin concentration in the medium and protein expression of HIF PHD2. These data suggest that erythropoietin is produced by the cortical nephrons mainly in the intercalated cells, but not in the peritubular cells, in normal hematopoietic condition and by mainly peritubular cells in hypoxia, suggesting the different regulation mechanism between the nephrons and peritubular cells. PMID:24832733

  13. [Backgrounds for assessing occupational exposure to crystalline silica dust in Poland and worldwide].

    PubMed

    Maciejewska, Aleksandra

    2007-01-01

    Crystalline silica is an agent harmful to human health, and quite frequently present in occupational environments. Occupational groups exposed to crystalline silica dust include mostly workers of the mineral and coal mining as well as metallurgical, chemical and construction industries. In the European Union (EU), the number of those exposed to this agent is estimated at over 2 million persons. In Poland, the number of people employed under conditions of excessive silica dust exposure exceeds 50 thousand. The assessment of occupational exposure to crystalline silica comprises several steps: primarily workplace determinations, quantitative sample analyses and comparisons of the obtained results with admissible values. This work describes a set of instruments that enables direct comparison of the study results with admissible values binding in almost 40 countries. It also highlights the consequences resulting from the classification of quartz and cristobalite, the most common forms of crystalline silica, as carcinogens by the International Agency for Research on Cancer (IARC). A survey of air sampling and dust determination methods used in various countries to measure airborne dust concentrations of crystalline silica in occupational environments are presented along with relevant tables. The GESTIS data base, specifying the methods considered by EU as suitable for measuring and assessing harmful agents, was used as the selection criterion. Particular attention was paid to the methods used to determine crystalline silica; the effect of analytical methods applied, sample preparation procedures, and reference materials on the results of determinations was also analyzed. Main parameters of method validation, such as detection and determination limits, and precision of the analysis were compared. PMID:18041202

  14. What Is Crystalline Silica?

    MedlinePlus

    ... silica, and requires a repirator protection program until engineering controls are implemented. Additionally, OSHA has a National ... silica materials with safer substitutes, whenever possible. ■ Provide engineering or administrative controls, where feasible, such as local ...

  15. Multifunctional mesoporous silica catalyst

    DOEpatents

    Lin, Victor Shang-Yi; Tsai, Chih-Hsiang; Chen, Hung-Ting; Pruski, Marek; Kobayashi, Takeshi

    2015-03-31

    The present invention provides bifunctional silica mesoporous materials, including mesoporous silica nanoparticles ("MSN"), having pores modified with diarylammonium triflate and perfluoroaryl moieties, that are useful for the acid-catalyzed esterification of organic acids with organic alcohols.

  16. FFTF (Fast Flux Test Facility) reactor shutdown system reliability reevaluation

    SciTech Connect

    Pierce, B.F.

    1986-07-01

    The reliability analysis of the Fast Flux Test Facility reactor shutdown system was reevaluated. Failure information based on five years of plant operating experience was used to verify original reliability numbers or to establish new ones. Also, system modifications made subsequent to performance of the original analysis were incorporated into the reevaluation. Reliability calculations and sensitivity analyses were performed using a commercially available spreadsheet on a personal computer. The spreadsheet was configured so that future failures could be tracked and compared with expected failures. A number of recommendations resulted from the reevaluation including both increased and decreased surveillance intervals. All recommendations were based on meeting or exceeding existing reliability goals. Considerable cost savings will be incurred upon implementation of the recommendations.

  17. Silica extraction from geothermal water

    SciTech Connect

    Bourcier, William L; Bruton, Carol J

    2014-09-23

    A method of producing silica from geothermal fluid containing low concentration of the silica of less than 275 ppm includes the steps of treating the geothermal fluid containing the silica by reverse osmosis treatment thereby producing a concentrated fluid containing the silica, seasoning the concentrated fluid thereby producing a slurry having precipitated colloids containing the silica, and separating the silica from the slurry.

  18. 12 CFR 1026.59 - Reevaluation of rate increases.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 8 2013-01-01 2013-01-01 false Reevaluation of rate increases. 1026.59 Section... credit plan. (2) Rate increases imposed between January 1, 2009 and February 21, 2010. For rate increases imposed between January 1, 2009 and February 21, 2010, an issuer must consider the factors described...

  19. 14 CFR 161.403 - Criteria for reevaluation.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...) AIRPORTS NOTICE AND APPROVAL OF AIRPORT NOISE AND ACCESS RESTRICTIONS Reevaluation of Stage 3 Restrictions... shall be based on the divergence of actual noise impact of the restriction from the estimated noise... B of this part that affect Stage 3 aircraft operations. An aircraft operator may submit to the...

  20. 24 CFR 58.47 - Re-evaluation of environmental assessments and other environmental findings.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 24 Housing and Urban Development 1 2011-04-01 2011-04-01 false Re-evaluation of environmental....47 Re-evaluation of environmental assessments and other environmental findings. (a) A responsible entity must re-evaluate its environmental findings to determine if the original findings are still...

  1. 34 CFR 300.305 - Additional requirements for evaluations and reevaluations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., Individualized Education Programs, and Educational Placements Evaluations and Reevaluations § 300.305 Additional requirements for evaluations and reevaluations. (a) Review of existing evaluation data. As part of an initial evaluation (if appropriate) and as part of any reevaluation under this part, the IEP Team and other...

  2. Silica-Ceria Hybrid Nanostructures

    SciTech Connect

    Munusamy, Prabhakaran; Sanghavi, Shail P.; Nachimuthu, Ponnusamy; Baer, Donald R.; Thevuthasan, Suntharampillai

    2012-04-25

    A new hybrid material system that consists of ceria attached silica nanoparticles has been developed. Because of the versatile properties of silica and versatile properties of silica and versatile properties of silica and versatile properties of silica and versatile properties of silica and versatile properties of silica and versatile properties of silica and versatile properties of silica and versatile properties of silica and versatile properties of silica and versatile properties of silica and versatile properties of silica and antioxidant properties of ceria nanoparticles, this material system is ideally suited for biomedical applications. The silica particles of size ~50nm were synthesized by the Stöber synthesis method and ceria nanoparticles of size ~2-3nm was attached to the silica surface using a hetrocoagulation method. The presence of silanol groups on the surface of silica particles mediated homogenous nucleation of ceria which were attached to silica surface by Si-O-Ce bonding. The formations of silica-ceria hybrid nanostructures were characterized by X-photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM). The HRTEM image confirms the formation of individual crystallites of ceria nanoparticles attached to the silica surface. The XPS analysis indicates that ceria nanoparticles are chemically bonded to surface of silica and possess mixture of +3 and +4 chemical states.

  3. Silazane to silica

    NASA Technical Reports Server (NTRS)

    Harvey, Gale A.

    1992-01-01

    Thin film silica and/or methyl silicone were detected on most external surfaces of the retrieved LDEF. Known sources of silicone in or on the LDEF appear inadequate to explain the ubiquitous presence of the silica and silicone films. Hexamethyldisilazane (HMDS) was used as the Challenger tile waterproofing compound for the Challenger/LDEF deployment mission. HMDS releases NH3 which depolymerizes silicone RTV's. Polyurethanes were also attacked. Much of the silica/silicone contamination of LDEF resulted from HMDS.

  4. Silazine to silica

    NASA Technical Reports Server (NTRS)

    Harvey, Gale A.

    1993-01-01

    Thin film silica and/or methyl silicone were detected on most external surfaces of the retrieved LDEF. Both solar ultraviolet radiation and atomic oxygen can convert silicones to silica. Known sources of silicone in or on the LDEF appear inadequate to explain the ubiquitous presence of the silica and silicone films. Hexamethyldisilazane (HMDS) was used as the Challenger tile waterproofing compound for the Challenger/LDEF deployment mission. HMDS is both volatile and chemically reactive at STP. In addition, HMDS releases NH3 which depolymerizes silicone RTV's. Polyurethanes are also depolymerized. Experiments are reported that indicate much of the silicone and silica contamination of LDEF resulted directly or indirectly from HMDS.

  5. Downregulation of cyclin D1-CDK4 protein in human embryonic lung fibroblasts (HELF) induced by silica is mediated through the ERK and JNK pathway.

    PubMed

    Shen, Fuhai; Fan, Xueyun; Liu, Bingci; Jia, Xiaowei; Gao, Ai; Du, Hongju; Ye, Meng; You, Baorong; Huang, Chuanshu; Shi, Xianglin

    2008-10-01

    Silica is a factor in the induction of acute injury and chronic pulmonary fibrosis. In 1996, silica was also listed as a human carcinogen by the International Agency for Research on Cancer (IARC). However, the molecular mechanisms involved in its pathologic effects are not well understood. We found that exposure of human embryonic lung fibroblasts (HELF) to crystalline silica for 2h decreased cyclin D1 and cyclin-dependent kinase 4 (CDK4) expression levels. Extracellular signal-regulated protein kinase (ERKs), c-Jun NH2-terminal amino kinase (JNKs), and p38 kinase, as well as their downstream transcription factor, AP-1, had different effects on the regulation of expression levels of cyclin D1 and CDK4 alterations induced by silica. Silica activates multiple signal transduction pathways involved in coordinating cellular responses to stress. We established the requirements for ERK and JNK, members of the mitogen-activated protein kinase (MAPK) family, in mediating G1 phase arrest of HELF induced by silica. Silica treatment activated ERK in a dose-dependent manner. AG126 (a chemical inhibitor of the ERK signaling pathway) and the dominant negative mutant of ERK2 (a molecular inhibitor of ERK2) prevented decreases in cyclin D1 and CDK4 expression levels. A chemical inhibitor of JNK, SP600125, prevented the decreased expression of both cyclin D1 and CDK4, whereas SB203580, a chemical inhibitor of p38, did not. Interestingly, curcumin prevented the decrease in DK4 expression, but not in cyclin D1. These results demonstrate that ERKs and JNKs are responsible for the decrease of cyclin D1 and CDK4 expression levels in HELF induced by silica. Activator protein-1 (AP-1) was responsible for the decrease of CDK4 expression level, but not that of cyclin D1. The findings help to explain the mechanisms of diseases induced by silica. PMID:18703151

  6. 78 FR 24439 - Compliance With Information Request, Flooding Hazard Reevaluation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-25

    ...The U.S. Nuclear Regulatory Commission (NRC) is issuing draft Japan Lessons-Learned Project Directorate Interim Staff Guidance (JLD- ISG), JLD-ISG-2013-01, ``Guidance for Estimating Flooding Hazards due to Dam Failure.'' This draft JLD-ISG provides guidance acceptable to the NRC staff for reevaluating flooding hazards due to dam failure for the purpose of responding to enclosure 2 of a March......

  7. Silica, Silicosis, and Autoimmunity

    PubMed Central

    Pollard, Kenneth Michael

    2016-01-01

    Inhalation of dust containing crystalline silica is associated with a number of acute and chronic diseases including systemic autoimmune diseases. Evidence for the link with autoimmune disease comes from epidemiological studies linking occupational exposure to crystalline silica dust with the systemic autoimmune diseases systemic lupus erythematosus, systemic sclerosis, and rheumatoid arthritis. Although little is known regarding the mechanism by which silica exposure leads to systemic autoimmune disease, there is a voluminous literature on silica exposure and silicosis that may help identify immune processes that precede development of autoimmunity. The pathophysiology of silicosis consists of deposition of silica particles in the alveoli of the lung. Ingestion of these particles by macrophages initiates an inflammatory response, which stimulates fibroblasts to proliferate and produce collagen. Silica particles are encased by collagen leading to fibrosis and the nodular lesions characteristic of the disease. The steps in the development of silicosis, including acute and chronic inflammation and fibrosis, have different molecular and cellular requirements, suggesting that silica-induced inflammation and fibrosis may be mechanistically separate. Significantly, it is unclear whether silica-induced inflammation and fibrosis contribute similarly to the development of autoimmunity. Nonetheless, the findings from human and animal model studies are consistent with an autoimmune pathogenesis that begins with activation of the innate immune system leading to proinflammatory cytokine production, pulmonary inflammation leading to activation of adaptive immunity, breaking of tolerance, and autoantibodies and tissue damage. The variable frequency of these immunological features following silica exposure suggests substantial genetic involvement and gene/environment interaction in silica-induced autoimmunity. However, numerous questions remain unanswered. PMID:27014276

  8. Silica, Silicosis, and Autoimmunity.

    PubMed

    Pollard, Kenneth Michael

    2016-01-01

    Inhalation of dust containing crystalline silica is associated with a number of acute and chronic diseases including systemic autoimmune diseases. Evidence for the link with autoimmune disease comes from epidemiological studies linking occupational exposure to crystalline silica dust with the systemic autoimmune diseases systemic lupus erythematosus, systemic sclerosis, and rheumatoid arthritis. Although little is known regarding the mechanism by which silica exposure leads to systemic autoimmune disease, there is a voluminous literature on silica exposure and silicosis that may help identify immune processes that precede development of autoimmunity. The pathophysiology of silicosis consists of deposition of silica particles in the alveoli of the lung. Ingestion of these particles by macrophages initiates an inflammatory response, which stimulates fibroblasts to proliferate and produce collagen. Silica particles are encased by collagen leading to fibrosis and the nodular lesions characteristic of the disease. The steps in the development of silicosis, including acute and chronic inflammation and fibrosis, have different molecular and cellular requirements, suggesting that silica-induced inflammation and fibrosis may be mechanistically separate. Significantly, it is unclear whether silica-induced inflammation and fibrosis contribute similarly to the development of autoimmunity. Nonetheless, the findings from human and animal model studies are consistent with an autoimmune pathogenesis that begins with activation of the innate immune system leading to proinflammatory cytokine production, pulmonary inflammation leading to activation of adaptive immunity, breaking of tolerance, and autoantibodies and tissue damage. The variable frequency of these immunological features following silica exposure suggests substantial genetic involvement and gene/environment interaction in silica-induced autoimmunity. However, numerous questions remain unanswered. PMID:27014276

  9. Application of silica nanoparticles for increased silica availability in maize

    NASA Astrophysics Data System (ADS)

    Suriyaprabha, R.; Karunakaran, G.; Yuvakkumar, R.; Prabu, P.; Rajendran, V.; Kannan, N.

    2013-02-01

    Silica nanoparticles were extracted from rice husk and characterised comprehensively. The synthesised silica powders were amorphous in size with 99.7% purity (20-40 nm). Nanosilica was amended with red soil at 15 kg ha-1 along with micron silica. The influence of nanoscale on silica uptake, accumulation and nutritional variations in maize roots were evaluated through the studies such as root sectioning, elemental analysis and physiological parameters (root length and silica content) and compared with micron silica and control. Nanosilica treated soil reveals enhanced silica uptake and elongated roots which make the plant to resist in stress conditions like drought.

  10. [The probability of developing brain tumours among users of cellular telephones (scientific information to the decision of the International Agency for Research on Cancer (IARC) announced on May 31, 2011)].

    PubMed

    Grigor'ev, Iu G

    2011-01-01

    The WHO's International Agency for Research on Cancer (IARC) has made May 31 2011 PRESS RELEASE No 208 which classifies radiofrequency electromagnetic fields as possibly carcinogenic to humans (Group 2B). The decision is based on an increased risk of glioma, i.e., a malignant type of brain cancer associated with the wireless phone use. This paper reports the analysis of the long-term research on the issue in question that had been carried out in many countries around the world before the decision was made. PMID:22279776

  11. New antifouling silica hydrogel.

    PubMed

    Beltrán-Osuna, Ángela A; Cao, Bin; Cheng, Gang; Jana, Sadhan C; Espe, Matthew P; Lama, Bimala

    2012-06-26

    In this work, a new antifouling silica hydrogel was developed for potential biomedical applications. A zwitterionic polymer, poly(carboxybetaine methacrylate) (pCBMA), was produced via atom-transfer radical polymerization and was appended to the hydrogel network in a two-step acid-base-catalyzed sol-gel process. The pCBMA silica aerogels were obtained by drying the hydrogels under supercritical conditions using CO(2). To understand the effect of pCBMA on the gel structure, pCBMA silica aerogels with different pCBMA contents were characterized using scanning electron microscopy (SEM), nuclear magnetic resonance (NMR) spectroscopy, and the surface area from Brauner-Emmet-Teller (BET) measurements. The antifouling property of pCBMA silica hydrogel to resist protein (fibrinogen) adsorption was measured using enzyme-linked immunosorbent assay (ELISA). SEM images revealed that the particle size and porosity of the silica network decreased at low pCBMA content and increased at above 33 wt % of the polymer. The presence of pCBMA increased the surface area of the material by 91% at a polymer content of 25 wt %. NMR results confirmed that pCBMA was incorporated completely into the silica structure at a polymer content below 20 wt %. A protein adsorption test revealed a reduction in fibrinogen adsorption by 83% at 25 wt % pCBMA content in the hydrogel compared to the fibrinogen adsorption in the unmodified silica hydrogel. PMID:22607091

  12. Oxygen configurations in silica

    SciTech Connect

    Chelikowsky, James R.; Chadi, D. J.; Binggeli, N.

    2000-07-15

    We propose a transition state for oxygen in silica. This state is produced by the insertion of an oxygen molecule into the Si-O-Si bond, i.e., it consists of producing a Si-O-O-O-Si bond. This state allows molecular oxygen diffusion in silica without breaking the molecular O{sub 2} bond and it is energetically more stable than a peroxy configuration. This configuration may allow for exchange of molecular oxygen with the oxygen in the silica framework. (c) 2000 The American Physical Society.

  13. Silica Embedded Metal Hydrides

    SciTech Connect

    Heung, L.K.; Wicks, G.G.

    1998-08-01

    A method to produce silica embedded metal hydride was developed. The product is a composite in which metal hydride particles are embedded in a matrix of silica. The silica matrix is highly porous. Hydrogen gas can easily reach the embedded metal hydride particles. The pores are small so that the metal hydride particles cannot leave the matrix. The porous matrix also protects the metal hydride particles from larger and reactive molecules such as oxygen, since the larger gas molecules cannot pass through the small pores easily. Tests show that granules of this composite can absorb hydrogen readily and withstand many cycles without making fines.

  14. Structural polarity in the Chara rhizoid: a reevaluation

    NASA Technical Reports Server (NTRS)

    Kiss, J. Z.; Staehelin, L. A.

    1993-01-01

    The Chara rhizoid is a useful model system to study gravitropism since all phases of gravitropism occur in a single cell. Despite years of study, a complete description of the distinctive ultrastructure of Chara rhizoids is not available. Therefore, in this paper, we reevaluate the ultrastructural features of vertically grown rhizoids, which have a structural polarity consisting of seven distinct zones. We also characterize the apical vesicles and the cell wall in these rhizoids by using antibodies against pectic polysaccharides. These studies demonstrate that the cell wall consists of two pectinaceous domains and that a distinct population of apical vesicles contain methyl esterified pectin.

  15. Cellulose-silica aerogels.

    PubMed

    Demilecamps, Arnaud; Beauger, Christian; Hildenbrand, Claudia; Rigacci, Arnaud; Budtova, Tatiana

    2015-05-20

    Aerogels based on interpenetrated cellulose-silica networks were prepared and characterised. Wet coagulated cellulose was impregnated with silica phase, polyethoxydisiloxane, using two methods: (i) molecular diffusion and (ii) forced flow induced by pressure difference. The latter allowed an enormous decrease in the impregnation times, by almost three orders of magnitude, for a sample with the same geometry. In both cases, nanostructured silica gel was in situ formed inside cellulose matrix. Nitrogen adsorption analysis revealed an almost threefold increase in pores specific surface area, from cellulose aerogel alone to organic-inorganic composite. Morphology, thermal conductivity and mechanical properties under uniaxial compression were investigated. Thermal conductivity of composite aerogels was lower than that of cellulose aerogel due to the formation of superinsulating mesoporous silica inside cellulose pores. Furthermore, composite aerogels were stiffer than each of reference aerogels. PMID:25817671

  16. Crystalline Silica Primer

    USGS Publications Warehouse

    Staff- Branch of Industrial Minerals

    1992-01-01

    substance and will present a nontechnical overview of the techniques used to measure crystalline silica. Because this primer is meant to be a starting point for anyone interested in learning more about crystalline silica, a list of selected readings and other resources is included. The detailed glossary, which defines many terms that are beyond the scope of this publication, is designed to help the reader move from this presentation to a more technical one, the inevitable next step.

  17. Silica, hybrid silica, hydride silica and non-silica stationary phases for liquid chromatography.

    PubMed

    Borges, Endler M

    2015-04-01

    Free silanols on the surface of silica are the "villains", which are responsible for detrimental interactions of those compounds and the stationary phase (i.e., bad peak shape, low efficiency) as well as low thermal and chemical stability. For these reasons, we began this review describing new silica and hybrid silica stationary phases, which have reduced and/or shielded silanols. At present, in liquid chromatography for the majority of analyses, reversed-phase liquid chromatography is the separation mode of choice. However, the needs for increased selectivity and increased retention of hydrophilic bases have substantially increased the interest in hydrophilic interaction chromatography (HILIC). Therefore, stationary phases and this mode of separation are discussed. Then, non-silica stationary phases (i.e., zirconium oxide, titanium oxide, alumina and porous graphitized carbon), which afford increased thermal and chemical stability and also selectivity different from those obtained with silica and hybrid silica, are discussed. In addition, the use of these materials in HILIC is also reviewed. PMID:25234386

  18. 24 CFR 965.407 - Reevaluations of master-meter systems.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 24 Housing and Urban Development 4 2014-04-01 2014-04-01 false Reevaluations of master-meter systems. 965.407 Section 965.407 Housing and Urban Development REGULATIONS RELATING TO HOUSING AND URBAN... Existing PHA-Owned Projects § 965.407 Reevaluations of master-meter systems. Because of changes in the...

  19. 12 CFR 160.172 - Re-evaluation of real estate owned.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 1 2014-01-01 2014-01-01 false Re-evaluation of real estate owned. 160.172... INVESTMENT § 160.172 Re-evaluation of real estate owned. A Federal savings association shall appraise each parcel of real estate owned at the earlier of in-substance foreclosure or at the time of the...

  20. 12 CFR 160.172 - Re-evaluation of real estate owned.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 1 2012-01-01 2012-01-01 false Re-evaluation of real estate owned. 160.172... INVESTMENT § 160.172 Re-evaluation of real estate owned. A Federal savings association shall appraise each parcel of real estate owned at the earlier of in-substance foreclosure or at the time of the...

  1. 12 CFR 560.172 - Re-evaluation of real estate owned.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 6 2012-01-01 2012-01-01 false Re-evaluation of real estate owned. 560.172 Section 560.172 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY LENDING AND INVESTMENT Lending and Investment Provisions Applicable to all Savings Associations § 560.172 Re-evaluation of real estate owned. A...

  2. 12 CFR 390.272 - Re-evaluation of real estate owned.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 5 2014-01-01 2014-01-01 false Re-evaluation of real estate owned. 390.272....272 Re-evaluation of real estate owned. A State savings association shall appraise each parcel of real... apply to any parcel of real estate that is sold and reacquired less than 12 months subsequent to...

  3. 12 CFR 390.272 - Re-evaluation of real estate owned.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 5 2013-01-01 2013-01-01 false Re-evaluation of real estate owned. 390.272....272 Re-evaluation of real estate owned. A State savings association shall appraise each parcel of real... apply to any parcel of real estate that is sold and reacquired less than 12 months subsequent to...

  4. 12 CFR 390.272 - Re-evaluation of real estate owned.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 5 2012-01-01 2012-01-01 false Re-evaluation of real estate owned. 390.272 Section 390.272 Banks and Banking FEDERAL DEPOSIT INSURANCE CORPORATION REGULATIONS AND STATEMENTS OF GENERAL POLICY REGULATIONS TRANSFERRED FROM THE OFFICE OF THRIFT SUPERVISION Lending and Investment § 390.272 Re-evaluation of real estate owned....

  5. 12 CFR 160.172 - Re-evaluation of real estate owned.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 1 2013-01-01 2013-01-01 false Re-evaluation of real estate owned. 160.172... INVESTMENT § 160.172 Re-evaluation of real estate owned. A Federal savings association shall appraise each parcel of real estate owned at the earlier of in-substance foreclosure or at the time of the...

  6. 24 CFR 58.47 - Re-evaluation of environmental assessments and other environmental findings.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... circumstances and environmental conditions which may affect the project or have a bearing on its impact, such as... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false Re-evaluation of environmental....47 Re-evaluation of environmental assessments and other environmental findings. (a) A...

  7. Kinetics of silica polymerization

    SciTech Connect

    Weres, O.; Yee, A.; Tsao, L.

    1980-05-01

    The polymerization of silicic acid in geothermal brine-like aqueous solutions to produce amorphous silica in colloidal form has been studied experimentally and theoretically. A large amount of high quality experimental data has been generated over the temperature rang 23 to 100{sup 0}C. Wide ranges of dissolved silica concentration, pH, and sodium chloride concentration were covered. The catalytic effects of fluoride and the reaction inhibiting effects of aluminum and boron were studied also. Two basic processes have been separately studied: the formation of new colloidal particles by the homogeneous nucleation process and the deposition of dissolved silica on pre-existing colloidal particles. A rigorous theory of the formation of colloidal particles of amorphous silica by homogeneous nucleation was developed. This theory employs the Lothe-Pound formalism, and is embodied in the computer code SILNUC which quantitatively models the homogeneous nucleation and growth of colloidal silica particles in more than enough detail for practical application. The theory and code were extensively used in planning the experimental work and analyzing the data produced. The code is now complete and running in its final form. It is capable of reproducing most of the experimental results to within experimental error. It is also capable of extrapolation to experimentally inaccessible conditions, i.e., high temperatures, rapidly varying temperature and pH, etc.

  8. Silica in alkaline brines

    USGS Publications Warehouse

    Jones, B.F.; Rettig, S.L.; Eugster, H.P.

    1967-01-01

    Analysis of sodium carbonate-bicarbonate brines from closed basins in volcanic terranes of Oregon and Kenya reveals silica contents of up to 2700 parts per million at pH's higher than 10. These high concentrations of SiO 2 can be attributed to reaction of waters with silicates, and subsequent evaporative concentration accompanied by a rise in pH. Supersaturation with respect to amorphous silica may occur and persist for brines that are out of contact with silicate muds and undersaturated with respect to trona; correlation of SiO2 with concentration of Na and total CO2 support this interpretation. Addition of moredilute waters to alkaline brines may lower the pH and cause inorganic precipitation of substantial amounts of silica.

  9. [Study of post marketing safety reevaluation of shenqi fuzheng injection].

    PubMed

    Ai, Qing-Hua; Li, Yuan-Yuan; Xie, Yan-Ming

    2014-09-01

    In order to promote the Shenqifuzheng injection (SQFZ) clinical medication safety, this study reevaluate on SQFZ post marketing safety study systematically. Including multi center large sample registration type safety monitoring research, the analysis based on national spontaneous reporting system data, the analysis based on the 20 national hospital information system data and literature research. Above the analysis, it suggests that SQFZ has good security. The more adverse drug reaction (ADR) as allergic reactions, mainly involved in the damage of skin, appendages and its systemic damage, serious person can appear allergic shock. ADR/E is more common in the elderly, may be related to medication (tumor) populations. Early warning analysis based on SRS data and literature research are of the view that "phlebitis" has a strong association with SQFZ used. PMID:25532410

  10. Re-evaluation of PRRT2 mutations in paroxysmal disorders.

    PubMed

    Guo, Xia Nan; Lu, Qiang; Zhou, Xiang Qin; Liu, Qing; Zhang, Xue; Cui, Li-Ying

    2014-05-01

    Mutations in PRRT2 have recently been identified as the major cause of autosomal dominant benign familial infantile epilepsy (BFIE), infantile convulsions with choreoathetosis syndrome (ICCA), and paroxysmal kinesigenic dyskinesia (PKD). Other paroxysmal disorders like febrile seizures, migraine, paroxysmal exercise-induced dyskinesia, and paroxysmal non-kinesigenic dyskinesia have also been shown to be associated with this gene. We re-evaluated PRRT2 mutations and genetic-clinical correlations in additional cases with PKD/ICCA and other paroxysmal disorders. Two novel mutations in PRRT2 were revealed in PKD/ICCA cases, while no mutations were detected in other diseases, which suggests BFIE and PKD are still core phenotypes of PRRT2-related spectrum disorders. PMID:24609974

  11. Silica Precipitation and Lithium Sorption

    SciTech Connect

    Jay Renew

    2015-09-20

    This file contains silica precipitation and lithium sorption data from the project. The silica removal data is corrected from the previous submission. The previous submission did not take into account the limit of detection of the ICP-MS procedure.

  12. Epoxy Grout With Silica Thickener

    NASA Technical Reports Server (NTRS)

    Mcclung, C. E.

    1984-01-01

    Grout cures quickly, even in presence of hydraulic oil. Grout is mixture of aggregate particles, finely-divided silica, epoxy resin, and triethylenetetramine curing agent, with mixture containing about 85 percent silica and aggregate particle sand 15 percent resin and curing agent. Silica is thickening agent and keeps grout from sagging.

  13. Overexpression of cyclin D1-CDK4 in silica-induced transformed cells is due to activation of ERKs, JNKs/AP-1 pathway.

    PubMed

    Shen, Fuhai; Fan, Xueyun; Liu, Bingci; Jia, Xiaowei; Du, Hongju; You, Baorong; Ye, Meng; Huang, Chuanshu; Shi, Xianglin

    2006-01-25

    Silica has been known to be a factor inducing acute injury and chronic pulmonary fibrosis. Silica has also been listed as a human carcinogen in 1996 by International Agency for Research on Cancer (IARC). However, the molecular mechanisms involved its pathologic effects are not well understood. In these studies, we found that exposure of human embryonic lung fibroblasts (HELF) to crystalline silica could cause increases in activation of extracellular signal-regulated kinases (ERKs), p38K, and c-Jun NH2-terminal amino kinases (JNKs), and HELF transformation. Interestingly, silica-induced transformation of HELF (S-HELF) led to increases in activated levels of ERKs and p46 of JNKs, and decrease in p38K activation, and no effect on activation of p54 of JNKs, as compared with those in parental HELF. Further studies showed that there are differential effects of ERKs, JNKs and p38K, as well as their downstream transcription factor AP-1, in regulation of expression of cyclin D1 and CDK4 and cell cycle alternations induced by silica. Cyclin D1 and CDK4 were increased in S-HELF as compared with those in HELF. Inhibition of ERKs activation by AG126, JNK by SP600125, and AP-1 by curcumin could reduced the induction of cyclin D1 and CDK4. There is no significant difference for cell cycle distribution between groups. These results demonstrate that ERKs and JNKs, but not p38K is responsible for induction of cyclin D1 and CDK4 in S-HELF, suggesting that overexpression of cyclin D1 and CDK4 caused by silica is mediated by ERK, JNK/AP-1signaling pathway. PMID:16125882

  14. Reevaluation of a Suspected Cronobacter sakazakii Outbreak in Mexico.

    PubMed

    Jackson, Emily E; Flores, Julio Parra; Fernández-Escartín, Eduardo; Forsythe, Stephen J

    2015-06-01

    In 2010, two infants became ill at a hospital in Mexico. Subsequently, a range of clinical, environmental, and powdered and rehydrated infant formula isolates were identified by using a combination of phenotyping and PCR probes. The strains were clustered according to pulsed-field gel electrophoresis. The causative agent was reported as Cronobacter sakazakii, with powdered infant formula (PIF) identified as the likely source of the infections. This new study further characterized the isolates from this outbreak by using multilocus sequence typing and whole genome sequencing of selected strains. Though four PIF isolates and one hospital environmental isolate were identified as C. sakazakii sequence type 297 by multilocus sequence typing, they were isolated 6 months prior to the outbreak. Genotypic analyses of patient isolates identified them as Enterobacter hormaechei and Enterobacter spp. The pulsed-field gel electrophoresis profile of the Enterobacter spp. isolates matched those of isolates from previously unopened tins of PIF. E. hormaechei was only isolated from the two infants and not PIF. The reevaluation of this outbreak highlights the need for accurate detection and identification assays, particularly during outbreak investigations in which incorrect identifications may mislead the investigation and attribution of the source. Though the species responsible for the symptoms could not be determined, this outbreak demonstrated the possible transmission of Enterobacter spp. from PIF to infants. These are possibly the first reported cases of Enterobacter spp. infection of infants from bacterial-contaminated PIF. PMID:26038912

  15. Reevaluation of a walleye (Sander vitreus) bioenergetics model

    USGS Publications Warehouse

    Madenjian, Charles P.; Wang, Chunfang

    2013-01-01

    Walleye (Sander vitreus) is an important sport fish throughout much of North America, and walleye populations support valuable commercial fisheries in certain lakes as well. Using a corrected algorithm for balancing the energy budget, we reevaluated the performance of the Wisconsin bioenergetics model for walleye in the laboratory. Walleyes were fed rainbow smelt (Osmerus mordax) in four laboratory tanks each day during a 126-day experiment. Feeding rates ranged from 1.4 to 1.7 % of walleye body weight per day. Based on a statistical comparison of bioenergetics model predictions of monthly consumption with observed monthly consumption, we concluded that the bioenergetics model estimated food consumption by walleye without any significant bias. Similarly, based on a statistical comparison of bioenergetics model predictions of weight at the end of the monthly test period with observed weight, we concluded that the bioenergetics model predicted walleye growth without any detectable bias. In addition, the bioenergetics model predictions of cumulative consumption over the 126-day experiment differed fromobserved cumulative consumption by less than 10 %. Although additional laboratory and field testing will be needed to fully evaluate model performance, based on our laboratory results, the Wisconsin bioenergetics model for walleye appears to be providing unbiased predictions of food consumption.

  16. Reevaluation of lake trout and lake whitefish bioenergetics models

    USGS Publications Warehouse

    Madenjian, Charles P.; Pothoven, Steve A.; Kao, Yu-Chun

    2013-01-01

    Using a corrected algorithm for balancing the energy budget, we reevaluated the Wisconsin bioenergetics model for lake trout (Salvelinus namaycush) in the laboratory and for lake whitefish (Coregonus clupeaformis) in the laboratory and in the field. For lake trout, results showed that the bioenergetics model slightly overestimated food consumption by the lake trout when they were fed low and intermediate rations, whereas the model predicted food consumption by lake trout fed ad libitum without any detectable bias. The slight bias in model predictions for lake trout on restricted rations may have been an artifact of the feeding schedule for these fish, and we would therefore recommend application of the Wisconsin lake trout bioenergetics model to lake trout populations in the field without any revisions to the model. Use of the Wisconsin bioenergetics model for coregonids resulted in overestimation of food consumption by lake whitefish both in the laboratory and in the field by between 20 and 30%, on average. This overestimation of food consumption was most likely due to overestimation of respiration rate. We therefore adjusted the respiration component of the bioenergetics model to obtain a good fit to the observed consumption in our laboratory tanks. The adjusted model predicted the consumption in the laboratory and the field without any detectable bias. Until a detailed lake whitefish respiration study can be conducted, we recommend application of our adjusted version of the Wisconsin generalized coregonid bioenergetics model to lake whitefish populations in the field.

  17. Reevaluation of the significance of sequence information for speech recognition

    NASA Astrophysics Data System (ADS)

    Sarukkai, Ramesh R.; Ballard, Dana H.

    1994-12-01

    A central difficulty with automatic speech recognition is the temporally inaccurate nature of the speech signal. Despite this, speech has been traditionally modeled as a purely sequential (albeit probabilistic) process. The usefulness of accurate sequence information is reevaluated in this paper, both at the acoustic and lexical levels for the task of speech recognition. At the acoustic level, speech segments are quantized into discrete vectors, and converted into set representations as opposed to accurate sequences. Recognition of the quantized vector sets dramatically improved performance as contrasted with the corresponding vector sequence representations. At the lexical level, our study suggests that accurate sequence information is, again, not crucial. In fact locally discarding phoneme sequence information may be useful for coping with errors (such as insertion, substitution). Based on the idea of phone set indexing, a lexical access algorithm is developed. Thus, this work questions the traditional approach of modeling speech as a purely sequential process, and suggests that discarding local sequential information may be a good idea. As an alternative to a purely sequential representation, a set representation seems to be a viable option.

  18. Reevaluation of the quondam dust trend in the middle atmosphere.

    PubMed

    Kocifaj, Miroslav; Horvath, Helmuth

    2005-12-01

    Quondam lunar eclipse photometry data offered valuable information on the optical properties of the middle atmosphere, including dust particles. However, in comparison with nonspherical grains, the simple model of spherical particles has a different effect on solar radiation penetrating horizontally through the atmosphere. It is shown that the systems, in which the smallest size fraction of dust particles dominates, reduce irradiation of the Earth's shadow more efficiently if the grains are of irregular shape. In contrast, the populations contaminated by a certain amount of large particles cause an opposite effect. Depending on the actual form of the size distribution function of the irregular grains, the irradiance within the center of the Earth's shadow may change by 2 orders of magnitude in the visible spectrum. It is therefore evident that dust properties retrieved in the past are eligible candidates for reevaluation to correct a view on the dust trend in the middle atmosphere. Sample calculations are presented for the lunar eclipse observed on 19 January 1954. PMID:16353810

  19. Re-evaluation of monitored retrievable storage concepts

    SciTech Connect

    Fletcher, J.F.; Smith, R.I.

    1989-04-01

    In 1983, as a prelude to the monitored retrievable storage (MRS) facility conceptual design, the Pacific Northwest Laboratory (PNL) conducted an evaluation for the US Department of Energy (DOE) that examined alternative concepts for storing spent LWR fuel and high- level wastes from fuel reprocessing. The evaluation was made considering nine concepts for dry away-from-reactor storage. The nine concepts evaluated were: concrete storage cask, tunnel drywell, concrete cask-in-trench, open-cycle vault, metal casks (transportable and stationary), closed-cycle vault, field drywell, and tunnel-rack vault. The purpose and scope of the re-evaluation did not require a repetition of the expert-based examinations used earlier. Instead, it was based on more detailed technical review by a small group, focusing on changes that had occurred since the initial evaluation was made. Two additional storage concepts--the water pool and the horizontal modular storage vault (NUHOMS system)--were ranked along with the original nine. The original nine concepts and the added two conceptual designs were modified as appropriate for a scenario with storage capacity for 15,000 MTU of spent fuel. Costs, area requirements, and technical and historical data pertaining to MRS storage were updated for each concept.

  20. Reevaluation of a walleye (Sander vitreus) bioenergetics model.

    PubMed

    Madenjian, Charles P; Wang, Chunfang

    2013-08-01

    Walleye (Sander vitreus) is an important sport fish throughout much of North America, and walleye populations support valuable commercial fisheries in certain lakes as well. Using a corrected algorithm for balancing the energy budget, we reevaluated the performance of the Wisconsin bioenergetics model for walleye in the laboratory. Walleyes were fed rainbow smelt (Osmerus mordax) in four laboratory tanks each day during a 126-day experiment. Feeding rates ranged from 1.4 to 1.7% of walleye body weight per day. Based on a statistical comparison of bioenergetics model predictions of monthly consumption with observed monthly consumption, we concluded that the bioenergetics model estimated food consumption by walleye without any significant bias. Similarly, based on a statistical comparison of bioenergetics model predictions of weight at the end of the monthly test period with observed weight, we concluded that the bioenergetics model predicted walleye growth without any detectable bias. In addition, the bioenergetics model predictions of cumulative consumption over the 126-day experiment differed from observed cumulative consumption by less than 10%. Although additional laboratory and field testing will be needed to fully evaluate model performance, based on our laboratory results, the Wisconsin bioenergetics model for walleye appears to be providing unbiased predictions of food consumption. PMID:23124865

  1. An empirical reevaluation of absolute pitch: behavioral and electrophysiological measurements.

    PubMed

    Elmer, Stefan; Sollberger, Silja; Meyer, Martin; Jäncke, Lutz

    2013-10-01

    Here, we reevaluated the "two-component" model of absolute pitch (AP) by combining behavioral and electrophysiological measurements. This specific model postulates that AP is driven by a perceptual encoding ability (i.e., pitch memory) plus an associative memory component (i.e., pitch labeling). To test these predictions, during EEG measurements AP and non-AP (NAP) musicians were passively exposed to piano tones (first component of the model) and additionally instructed to judge whether combinations of tones and labels were conceptually associated or not (second component of the model). Auditory-evoked N1/P2 potentials did not reveal differences between the two groups, thus indicating that AP is not necessarily driven by a differential pitch encoding ability at the processing level of the auditory cortex. Otherwise, AP musicians performed the conceptual association task with an order of magnitude better accuracy and shorter RTs than NAP musicians did, this result clearly pointing to distinctive conceptual associations in AP possessors. Most notably, this behavioral superiority was reflected by an increased N400 effect and accompanied by a subsequent late positive component, the latter not being distinguishable in NAP musicians. PMID:23647515

  2. Arsenic hydrogeochemistry in an irrigated river valley - A reevaluation

    USGS Publications Warehouse

    Nimick, D.A.

    1998-01-01

    Arsenic concentrations in ground water of the lower Madison River valley, Montana, are high (16 to 176 ??g/L). Previous studies hypothesized that arsenic-rich river water, applied as irrigation, was evapoconcentrated during recharge and contaminated the thin alluvial aquifer. Based on additional data collection and a reevaluation of the hydrology and geochemistry of the valley, the high arsenic concentrations in ground water are caused by a unique combination of natural hydrologic and geochemical factors, and irrigation appears to play a secondary role. The high arsenic concentrations in ground water have several causes: direct aquifer recharge by Madison River water having arsenic concentrations as high as 100 ??g/L, leaching of arsenic from Tertiary volcano-clastic sediment, and release of sorbed arsenic where redox conditions in ground water are reduced. The findings are consistent with related studies that demonstrate that arsenic is sorbed by irrigated soils in the valley. Although evaporation of applied irrigation water does not significantly increase arsenic concentrations in ground water, irrigation with arsenic-rich water raises other environmental concerns.

  3. Reevaluating the potency of the memory conformity effect.

    PubMed

    Bodner, Glen E; Musch, Elisabeth; Azad, Tanjeem

    2009-12-01

    Witnesses sometimes report event details that are acquired solely from another witness. We reevaluated the potency of this memory conformity effect. After viewing a crime video, some participants learned about nonwitnessed details via discussion (dyad group), reading another participant's report (read group), or watching another version of the video (both-video group). In Experiment 1, these participants often reported nonwitnessed details, but on a source-judgment test most details were attributed primarily to the actual source rather than to the video. In addition, the dyad group was not more likely than the read or both-video groups to report nonwitnessed details. Participants in Experiment 2 were explicitly discouraged from providing details that were remembered from the secondary source only. These postwarning instructions substantially reduced the memory conformity effect, and a dyad group was not more likely than a read group to report nonwitnessed details. Encouraging source monitoring at test can reduce the negative consequences of co-witness collaboration. PMID:19933452

  4. Modeling vitreous silica bilayers

    NASA Astrophysics Data System (ADS)

    Kumar, Avishek; Wilson, Mark; Sherrington, David; Thorpe, Michael

    2014-03-01

    The recent synthesis and imaging of bilayers of vitreous silica has led to a wealth of new information. We have modeled the experimentally-observed bilayer using a computer assembly procedure to form a network of corner-sharing tetrahedra, which is then mirror-reflected to form a bilayer. We show that the vitreous silica bilayer has additional macroscopic degrees of freedom iff there is a symmetry plane through the center of the bilayer going through the central layer of oxygen ions that join the upper and lower monolayers. We have computer-refined the experimental coordinates to determine the density, and other structural characteristics such as the Si-Si pair distribution function, Si-O-Si bond angle distribution and the Aboav-Weaire law.

  5. Viscoelasticity of silica gels

    SciTech Connect

    Scherer, G.W.

    1995-12-01

    The response of silica gels to mechanical loads depends on the properties of the solid phase and the permeability of the network. Understanding this behavior is essential for modeling of stresses developed during drying or heating of gels. The permeability and the mechanical properties are readily determined from a simple beam-bending experiment, by measuring the load relaxation that occurs at constant deflection. Load decay results from movement of the liquid within the network; in addition, there may be viscoelastic relaxation of the network itself. Silica gel is viscoelastic in chemically aggressive media, but in inert liquids (such as ethanol or acetone) it is elastic. Experiments show that the viscoelastic relaxation time decreases as the concentration and pH of the water in the pore liquid increase. During drying, the permeability decreases and the viscosity increases, both exhibiting a power-law dependence on density of the gel network.

  6. 42 CFR 405.213 - Re-evaluation of a device categorization.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... SERVICES MEDICARE PROGRAM FEDERAL HEALTH INSURANCE FOR THE AGED AND DISABLED Medical Services Coverage Decisions That Relate to Health Care Technology § 405.213 Re-evaluation of a device categorization....

  7. 42 CFR 405.213 - Re-evaluation of a device categorization.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... SERVICES MEDICARE PROGRAM FEDERAL HEALTH INSURANCE FOR THE AGED AND DISABLED Medical Services Coverage Decisions That Relate to Health Care Technology § 405.213 Re-evaluation of a device categorization....

  8. 42 CFR 405.213 - Re-evaluation of a device categorization.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... SERVICES MEDICARE PROGRAM FEDERAL HEALTH INSURANCE FOR THE AGED AND DISABLED Medical Services Coverage Decisions That Relate to Health Care Technology § 405.213 Re-evaluation of a device categorization....

  9. 42 CFR 405.213 - Re-evaluation of a device categorization.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... SERVICES MEDICARE PROGRAM FEDERAL HEALTH INSURANCE FOR THE AGED AND DISABLED Medical Services Coverage Decisions That Relate to Health Care Technology § 405.213 Re-evaluation of a device categorization....

  10. Five-Year NRHP Re-Evaluation of Historic Buildings Assessment

    SciTech Connect

    Ullrich, R A; Heidecker, K R

    2011-09-12

    The Lawrence Livermore National Laboratory (LLNL) 'Draft Programmatic Agreement among the Department of Energy and the California State Historic Preservation Officer Regarding Operation of Lawrence Livermore National Laboratory' requires a review and re-evaluation of the eligibility of laboratory properties for the National Register of Historic Places (NRHP) every five years. The original evaluation was published in 2005; this report serves as the first five-year re-evaluation. This re-evaluation includes consideration of changes within LLNL to management, to mission, and to the built environment. it also determines the status of those buildings, objects, and districts that were recommended as NRHP-eligible in the 2005 report. Buildings that were omitted from the earlier building list, those that have reached 50 years of age since the original assessment, and new buildings are also addressed in the re-evaluation.

  11. A reevaluation of the occurrence of ground water in the Nahiku area, East Maui, Hawaii

    USGS Publications Warehouse

    Meyer, William

    2000-01-01

    A reevaluation of existing hydrologic data indicates the existence of a vertically extensive ground water body in the Nahiku area of Maui rather than a succession of perched water bodies as had been previously assumed.

  12. 21 CFR 182.1711 - Silica aerogel.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Silica aerogel. 182.1711 Section 182.1711 Food and... GENERALLY RECOGNIZED AS SAFE Multiple Purpose GRAS Food Substances § 182.1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam having a minimum silica content of...

  13. 21 CFR 582.1711 - Silica aerogel.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Silica aerogel. 582.1711 Section 582.1711 Food and....1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam having a minimum silica content of 89.5 percent. (b) (c) Limitations, restrictions, or explanation....

  14. 21 CFR 582.1711 - Silica aerogel.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Silica aerogel. 582.1711 Section 582.1711 Food and....1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam having a minimum silica content of 89.5 percent. (b) (c) Limitations, restrictions, or explanation....

  15. 21 CFR 182.1711 - Silica aerogel.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Silica aerogel. 182.1711 Section 182.1711 Food and....1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam having a minimum silica content of 89.5 percent. (b) (c) Limitations, restrictions, or explanation....

  16. 21 CFR 582.1711 - Silica aerogel.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Silica aerogel. 582.1711 Section 582.1711 Food and....1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam having a minimum silica content of 89.5 percent. (b) (c) Limitations, restrictions, or explanation....

  17. 21 CFR 582.1711 - Silica aerogel.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Silica aerogel. 582.1711 Section 582.1711 Food and....1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam having a minimum silica content of 89.5 percent. (b) (c) Limitations, restrictions, or explanation....

  18. 21 CFR 182.1711 - Silica aerogel.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Silica aerogel. 182.1711 Section 182.1711 Food and....1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam having a minimum silica content of 89.5 percent. (b) (c) Limitations, restrictions, or explanation....

  19. 21 CFR 182.1711 - Silica aerogel.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Silica aerogel. 182.1711 Section 182.1711 Food and....1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam having a minimum silica content of 89.5 percent. (b) (c) Limitations, restrictions, or explanation....

  20. Nanoscale plasticity in silica glass

    SciTech Connect

    Glosli, J.N.; Boercker, D.B.; Tesar, A.; Belak, J.

    1993-10-01

    Mechanisms of nano-scale plasticity and damage initiation in silica glass is examined using molecular dynamics simulation. Computer experiments are carried out by indenting a sharp diamond-like tool, containing 4496 atoms, into a silica slab consisting of 12288 atoms. Both elastic and plastic deformation of silica is observed during nanoindentation simulation; this transition occurs at an indentation of 1.25 nm, and the calculated hardness (15GPa for 1.5 nm indentation) agrees with experiment.

  1. Reevaluating the functional implications of Australopithecus afarensis navicular morphology.

    PubMed

    Prang, Thomas C

    2016-08-01

    The longitudinal arch is a unique characteristic of the human foot, yet the timing and pattern of its evolution remain controversial, in part due to the disagreement among researchers over which skeletal traits are the best indicators of its presence or absence. The small size of the human navicular tuberosity has previously been linked to the presence of a longitudinal arch, implying that the large tuberosity of early hominins such as Australopithecus afarensis reflects a flat foot. However, this hypothesis is at odds with other evidence of pedal form and function, such as metatarsal, tarsal, and footprint morphology, which show that a longitudinal arch was probably present in A. afarensis. This study reevaluates the morphometric affinities of the A. afarensis naviculars among other Plio-Pleistocene fossil hominins and anthropoid primates (N = 170). Multivariate cluster analyses show that all fossil hominin naviculars, including those attributed to A. afarensis, are most similar to modern humans. A measure of navicular tuberosity size quantified as the ratio of the tuberosity volume to the surface area of the talar facet shows that Ateles has the largest navicular tuberosity among the anthropoid sample and that there is no difference between highly arboreal and terrestrial taxa in this metric (e.g., Hylobates and Gorilla beringei). Instead, a relatively large navicular tuberosity may reflect the development of leg musculature associated with ankle plantarflexion. The functional inferences derived from the morphology of the A. afarensis naviculars are consistent with the morphology of the Laetoli footprints. PMID:27457546

  2. Carbon in, Carbon out: Reevaluating Carbon Fluxes in Subduction Zones

    NASA Astrophysics Data System (ADS)

    Manning, C. E.; Kelemen, P. B.

    2015-12-01

    Subduction zones exert a fundamental control on the deep carbon cycle. We reevaluated carbon inputs and outputs in convergent margins considering new estimates of C concentration in subducting mantle peridotites, carbonate solubility in aqueous fluids along subduction geotherms, melting and diapirism of carbon-bearing metasediments, and diffuse degassing from arcs. Our updated estimate of carbon inputs to the global subduction system, which includes estimates for C in altered peridotite, is 40-66 megatons carbon/year (MtC/y). We find that estimates of C lost from slabs (14-66 MtC/y) must take into account the high CaCO3 solubility in aqueous fluids, which contributes significant C that must be added to that derived from mineral decarbonation reactions. When taken together with hydrous silicate and carbonatite melts and metasediment diapirs, nearly all C can be scavenged from subducting lithosphere. The return of C to the atmosphere via arc-volcano degassing is only 18-43 MtC/y, but consideration deep volatile saturation of arc magmas, magma ponding in the middle and deep arc crust, and CO2 venting in forearcs can account for the remaining C lost from the slab. Thus, whereas previous studies concluded that about half the subducting carbon is returned to the convecting mantle, we find that relatively little carbon may be recycled. If so, substantial quantities of carbon are stored in the mantle lithosphere and crust and the carbon content of the mantle lithosphere + crust + ocean + atmosphere must be increasing, at least over the last 5-10 My. This is consistent with inferences from noble gas data. Recycled carbon in diamonds is a small fraction of the global carbon inventory.

  3. Reevaluating Assembly Evaluations with Feature Response Curves: GAGE and Assemblathons

    PubMed Central

    Vezzi, Francesco; Narzisi, Giuseppe; Mishra, Bud

    2012-01-01

    In just the last decade, a multitude of bio-technologies and software pipelines have emerged to revolutionize genomics. To further their central goal, they aim to accelerate and improve the quality of de novo whole-genome assembly starting from short DNA sequences/reads. However, the performance of each of these tools is contingent on the length and quality of the sequencing data, the structure and complexity of the genome sequence, and the resolution and quality of long-range information. Furthermore, in the absence of any metric that captures the most fundamental “features” of a high-quality assembly, there is no obvious recipe for users to select the most desirable assembler/assembly. This situation has prompted the scientific community to rely on crowd-sourcing through international competitions, such as Assemblathons or GAGE, with the intention of identifying the best assembler(s) and their features. Somewhat circuitously, the only available approach to gauge de novo assemblies and assemblers relies solely on the availability of a high-quality fully assembled reference genome sequence. Still worse, reference-guided evaluations are often both difficult to analyze, leading to conclusions that are difficult to interpret. In this paper, we circumvent many of these issues by relying upon a tool, dubbed , which is capable of evaluating de novo assemblies from the read-layouts even when no reference exists. We extend the FRCurve approach to cases where lay-out information may have been obscured, as is true in many deBruijn-graph-based algorithms. As a by-product, FRCurve now expands its applicability to a much wider class of assemblers – thus, identifying higher-quality members of this group, their inter-relations as well as sensitivity to carefully selected features, with or without the support of a reference sequence or layout for the reads. The paper concludes by reevaluating several recently conducted assembly competitions and the datasets that have

  4. Re-evaluating the treatment of acute optic neuritis

    PubMed Central

    Bennett, Jeffrey L; Nickerson, Molly; Costello, Fiona; Sergott, Robert C; Calkwood, Jonathan C; Galetta, Steven L; Balcer, Laura J; Markowitz, Clyde E; Vartanian, Timothy; Morrow, Mark; Moster, Mark L; Taylor, Andrew W; Pace, Thaddeus W W; Frohman, Teresa; Frohman, Elliot M

    2015-01-01

    Clinical case reports and prospective trials have demonstrated a reproducible benefit of hypothalamic-pituitary-adrenal (HPA) axis modulation on the rate of recovery from acute inflammatory central nervous system (CNS) demyelination. As a result, corticosteroid preparations and adrenocorticotrophic hormones are the current mainstays of therapy for the treatment of acute optic neuritis (AON) and acute demyelination in multiple sclerosis. Despite facilitating the pace of recovery, HPA axis modulation and corticosteroids have failed to demonstrate long-term benefit on functional recovery. After AON, patients frequently report visual problems, motion perception difficulties and abnormal depth perception despite ‘normal’ (20/20) vision. In light of this disparity, the efficacy of these and other therapies for acute demyelination require re-evaluation using modern, high-precision paraclinical tools capable of monitoring tissue injury. In no arena is this more amenable than AON, where a new array of tools in retinal imaging and electrophysiology has advanced our ability to measure the anatomic and functional consequences of optic nerve injury. As a result, AON provides a unique clinical model for evaluating the treatment response of the derivative elements of acute inflammatory CNS injury: demyelination, axonal injury and neuronal degeneration. In this article, we examine current thinking on the mechanisms of immune injury in AON, discuss novel technologies for the assessment of optic nerve structure and function, and assess current and future treatment modalities. The primary aim is to develop a framework for rigorously evaluating interventions in AON and to assess their ability to preserve tissue architecture, re-establish normal physiology and restore optimal neurological function. PMID:25355373

  5. Re-evaluating the treatment of acute optic neuritis.

    PubMed

    Bennett, Jeffrey L; Nickerson, Molly; Costello, Fiona; Sergott, Robert C; Calkwood, Jonathan C; Galetta, Steven L; Balcer, Laura J; Markowitz, Clyde E; Vartanian, Timothy; Morrow, Mark; Moster, Mark L; Taylor, Andrew W; Pace, Thaddeus W W; Frohman, Teresa; Frohman, Elliot M

    2015-07-01

    Clinical case reports and prospective trials have demonstrated a reproducible benefit of hypothalamic-pituitary-adrenal (HPA) axis modulation on the rate of recovery from acute inflammatory central nervous system (CNS) demyelination. As a result, corticosteroid preparations and adrenocorticotrophic hormones are the current mainstays of therapy for the treatment of acute optic neuritis (AON) and acute demyelination in multiple sclerosis.Despite facilitating the pace of recovery, HPA axis modulation and corticosteroids have failed to demonstrate long-term benefit on functional recovery. After AON, patients frequently report visual problems, motion perception difficulties and abnormal depth perception despite 'normal' (20/20) vision. In light of this disparity, the efficacy of these and other therapies for acute demyelination require re-evaluation using modern, high-precision paraclinical tools capable of monitoring tissue injury.In no arena is this more amenable than AON, where a new array of tools in retinal imaging and electrophysiology has advanced our ability to measure the anatomic and functional consequences of optic nerve injury. As a result, AON provides a unique clinical model for evaluating the treatment response of the derivative elements of acute inflammatory CNS injury: demyelination, axonal injury and neuronal degeneration.In this article, we examine current thinking on the mechanisms of immune injury in AON, discuss novel technologies for the assessment of optic nerve structure and function, and assess current and future treatment modalities. The primary aim is to develop a framework for rigorously evaluating interventions in AON and to assess their ability to preserve tissue architecture, re-establish normal physiology and restore optimal neurological function. PMID:25355373

  6. Biogeochemistry: Silica cycling over geologic time

    NASA Astrophysics Data System (ADS)

    Conley, Daniel J.; Carey, Joanna C.

    2015-06-01

    The Earth's long-term silica cycle is intimately linked to weathering rates and biogenic uptake. Changes in weathering rates and the retention of silica on land have altered silica availability in the oceans for hundreds of millions of years.

  7. ZBLAN, Silica Fiber Comparison

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This graph depicts the increased signal quality possible with optical fibers made from ZBLAN, a family of heavy-metal fluoride glasses (fluorine combined zirconium, barium, lanthanum, aluminum, and sodium) as compared to silica fibers. NASA is conducting research on pulling ZBLAN fibers in the low-g environment of space to prevent crystallization that limits ZBLAN's usefulness in optical fiber-based communications. In the graph, a line closer to the black theoretical maximum line is better. Photo credit: NASA/Marshall Space Flight Center

  8. Silica Fillers for elastomer Reinforement

    SciTech Connect

    Kohls, D.J.; Schaefer, D.W.

    2009-08-26

    This article summarizes recent work on the structure of precipitated silica used in the reinforcement of elastomers. Silica has a unique morphology, consisting of multiple structural levels that can be controlled through processing. The ability to control and characterize the multiple structures of precipitated silica is an example of morphological engineering for reinforcement applications. In this summary of some recent research efforts using precipitated silica, small-angle scattering techniques are described and their usefulness for determining the morphology of silica in terms of primary particles, aggregates, and agglomerates are discussed. The structure of several different precipitated silica powders is shown as well as the mechanical properties of elastomers reinforced with these silica particles. The study of the mechanical properties of filled elastomer systems is a challenging and exciting topic for both fundamental science and industrial application. It is known that the addition of hard particulates to a soft elastomer matrix results in properties that do not follow a straightforward rule of mixtures. Research efforts in this area have shown that the properties of filled elastomers are influenced by the nature of both the filler and the matrix, as well as the interactions between them. Several articles have reviewed the influence of fillers like silica and carbon black on the reinforcement of elastomers. In general, the structure-property relationships developed for filled elastomers have evolved into the following major areas: Filler structure, hydrodynamic reinforcement, and interactions between fillers and elastomers.

  9. Silica Fillers for elastomer Reinforement

    SciTech Connect

    Kohls, D.J.; Schaefer, D.W.

    2012-09-10

    This article summarizes recent work on the structure of precipitated silica used in the reinforcement of elastomers. Silica has a unique morphology, consisting of multiple structural levels that can be controlled through processing. The ability to control and characterize the multiple structures of precipitated silica is an example of morphological engineering for reinforcement applications. In this summary of some recent research efforts using precipitated silica, small-angle scattering techniques are described and their usefulness for determining the morphology of silica in terms of primary particles, aggregates, and agglomerates are discussed. The structure of several different precipitated silica powders is shown as well as the mechanical properties of elastomers reinforced with these silica particles. The study of the mechanical properties of filled elastomer systems is a challenging and exciting topic for both fundamental science and industrial application. It is known that the addition of hard particulates to a soft elastomer matrix results in properties that do not follow a straightforward rule of mixtures. Research efforts in this area have shown that the properties of filled elastomers are influenced by the nature of both the filler and the matrix, as well as the interactions between them. Several articles have reviewed the influence of fillers like silica and carbon black on the reinforcement of elastomers. In general, the structure-property relationships developed for filled elastomers have evolved into the following major areas: Filler structure, hydrodynamic reinforcement, and interactions between fillers and elastomers.

  10. Silaffins in Silica Biomineralization and Biomimetic Silica Precipitation

    PubMed Central

    Lechner, Carolin C.; Becker, Christian F. W.

    2015-01-01

    Biomineralization processes leading to complex solid structures of inorganic material in biological systems are constantly gaining attention in biotechnology and biomedical research. An outstanding example for biomineral morphogenesis is the formation of highly elaborate, nano-patterned silica shells by diatoms. Among the organic macromolecules that have been closely linked to the tightly controlled precipitation of silica in diatoms, silaffins play an extraordinary role. These peptides typically occur as complex posttranslationally modified variants and are directly involved in the silica deposition process in diatoms. However, even in vitro silaffin-based peptides alone, with and without posttranslational modifications, can efficiently mediate biomimetic silica precipitation leading to silica material with different properties as well as with encapsulated cargo molecules of a large size range. In this review, the biomineralization process of silica in diatoms is summarized with a specific focus on silaffins and their in vitro silica precipitation properties. Applications in the area of bio- and nanotechnology as well as in diagnostics and therapy are discussed. PMID:26295401

  11. Silaffins in Silica Biomineralization and Biomimetic Silica Precipitation.

    PubMed

    Lechner, Carolin C; Becker, Christian F W

    2015-08-01

    Biomineralization processes leading to complex solid structures of inorganic material in biological systems are constantly gaining attention in biotechnology and biomedical research. An outstanding example for biomineral morphogenesis is the formation of highly elaborate, nano-patterned silica shells by diatoms. Among the organic macromolecules that have been closely linked to the tightly controlled precipitation of silica in diatoms, silaffins play an extraordinary role. These peptides typically occur as complex posttranslationally modified variants and are directly involved in the silica deposition process in diatoms. However, even in vitro silaffin-based peptides alone, with and without posttranslational modifications, can efficiently mediate biomimetic silica precipitation leading to silica material with different properties as well as with encapsulated cargo molecules of a large size range. In this review, the biomineralization process of silica in diatoms is summarized with a specific focus on silaffins and their in vitro silica precipitation properties. Applications in the area of bio- and nanotechnology as well as in diagnostics and therapy are discussed. PMID:26295401

  12. Reevaluation of upper Jurassic Morrison Formation, Western Interior

    SciTech Connect

    Mantzios, C.

    1989-03-01

    Comparison of the Brushy Basin member of the Upper Jurassic Morrison Formation in the Colorado Plateau with the Upper Jurassic-Lower Cretaceous Morrison-Cloverly sequence in the Bighorn basin, Wyoming, shows great similarities in their depositional environments and stratigraphy. The lower Brushy Basin member is a fluvial deposit composed of channel sandstones and overbank mudstones which display a great number of pedogenic features. Similar depositional setting has been observed in the Morrison Formation in the Bighorn basin, Wyoming, where pedogenic features suggest a distal floodplain setting with low-sinuosity channels cutting through. In both localities the dominant clay mineral is illite. The upper Brushy Basin member in the Colorado Plateau is composed mostly of gray and purpose mudstones rich in montmorillonite. Devitrified tuff beds and bentonite occur in certain levels throughout the unit. Pedogenic features are not conspicuously developed. The Lower Cretaceous Clovery Formation in the Bighorn basin, Wyoming, is strikingly similar in terms of lithological aspects. The depositional environment is interpreted in both localities as a playa deposit. A great variety of nodules is present such as silcretes, septaria, and silica-carbonate nodules. Radiometric dating of bentonites in central Utah revealed that the upper Brushy Basin member is Early Cretaceous in age. Field and geochemical data support these conclusions and aid the understanding of the exact nature of the depositional basin, environments, stratigraphy, and paleotectonics of the Upper Jurassic-Lower Cretaceous interval in the Western Interior.

  13. Silica research in Glasgow

    NASA Astrophysics Data System (ADS)

    Barr, B. W.; Cagnoli, G.; Casey, M. M.; Clubley, D.; Crooks, D. R. M.; Danzmann, K.; Elliffe, E. J.; Goßler, S.; Grant, A.; Grote, H.; Heptonstall, A.; Hough, J.; Jennrich, O.; Lück, H.; McIntosh, S. A.; Newton, G. P.; Palmer, D. A.; Plissi, M. V.; Robertson, D. I.; Robertson, N. A.; Rowan, S.; Skeldon, K. D.; Sneddon, P.; Strain, K. A.; Torrie, C. I.; Ward, H.; Willems, P. A.; Willke, B.; Winkler, W.

    2002-04-01

    The Glasgow group is involved in the construction of the GEO600 interferometer as well as in R&D activity on technology for advanced gravitational wave detectors. GEO600 will be the first GW detector using quasi-monolithic silica suspensions in order to decrease thermal noise significantly with respect to steel wire suspensions. The results concerning GEO600 suspension mounting and performance will be shown in the first section. Section 2 is devoted to the present results from the direct measurement of thermal noise in mirrors mounted in the 10 m interferometer in Glasgow which has a sensitivity limit of 4 × 10-19 m Hz-1/2 above 1 kHz. Section 3 presents results on the measurements of coating losses. R&D activity has been carried out to understand better how thermal noise in the suspensions affects the detector sensitivity, and in section 4 a discussion on the non-linear thermoelastic effect is presented.

  14. Silica aerogel core waveguide.

    PubMed

    Grogan, M D W; Leon-Saval, S G; England, R; Birks, T A

    2010-10-11

    We have selectively filled the core of hollow photonic crystal fibre with silica aerogel. Light is guided in the aerogel core, with a measured attenuation of 0.2 dB/cm at 1540 nm comparable to that of bulk aerogel. The structure guides light by different mechanisms depending on the wavelength. At long wavelengths the effective index of the microstructured cladding is below the aerogel index of 1.045 and guidance is by total internal reflection. At short wavelengths, where the effective cladding index exceeds 1.045, a photonic bandgap can guide the light instead. There is a small region of crossover, where both index- and bandgap-guided modes were simultaneously observed. PMID:20941148

  15. 21 CFR 584.700 - Hydrophobic silicas.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Hydrophobic silicas. 584.700 Section 584.700 Food... DRINKING WATER OF ANIMALS Listing of Specific Substances Affirmed as GRAS § 584.700 Hydrophobic silicas. (a) Product. Amorphous fumed hydrophobic silica or precipitated hydrophobic silica (CAS Reg. No....

  16. 21 CFR 584.700 - Hydrophobic silicas.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Hydrophobic silicas. 584.700 Section 584.700 Food... DRINKING WATER OF ANIMALS Listing of Specific Substances Affirmed as GRAS § 584.700 Hydrophobic silicas. (a) Product. Amorphous fumed hydrophobic silica or precipitated hydrophobic silica (CAS Reg. No....

  17. 21 CFR 584.700 - Hydrophobic silicas.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Hydrophobic silicas. 584.700 Section 584.700 Food... DRINKING WATER OF ANIMALS Listing of Specific Substances Affirmed as GRAS § 584.700 Hydrophobic silicas. (a) Product. Amorphous fumed hydrophobic silica or precipitated hydrophobic silica (CAS Reg. No....

  18. 21 CFR 584.700 - Hydrophobic silicas.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Hydrophobic silicas. 584.700 Section 584.700 Food... DRINKING WATER OF ANIMALS Listing of Specific Substances Affirmed as GRAS § 584.700 Hydrophobic silicas. (a) Product. Amorphous fumed hydrophobic silica or precipitated hydrophobic silica (CAS Reg. No....

  19. 21 CFR 582.1711 - Silica aerogel.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Silica aerogel. 582.1711 Section 582.1711 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam...

  20. 21 CFR 182.1711 - Silica aerogel.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Silica aerogel. 182.1711 Section 182.1711 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN....1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam...

  1. Silica/Polymer and Silica/Polymer/Fiber Composite Aerogels

    NASA Technical Reports Server (NTRS)

    Ou, Danny; Stepanian, Christopher J.; Hu, Xiangjun

    2010-01-01

    Aerogels that consist, variously, of neat silica/polymer alloys and silica/polymer alloy matrices reinforced with fibers have been developed as materials for flexible thermal-insulation blankets. In comparison with prior aerogel blankets, these aerogel blankets are more durable and less dusty. These blankets are also better able to resist and recover from compression . an important advantage in that maintenance of thickness is essential to maintenance of high thermal-insulation performance. These blankets are especially suitable as core materials for vacuum- insulated panels and vacuum-insulated boxes of advanced, nearly seamless design. (Inasmuch as heat leakage at seams is much greater than heat leakage elsewhere through such structures, advanced designs for high insulation performance should provide for minimization of the sizes and numbers of seams.) A silica/polymer aerogel of the present type could be characterized, somewhat more precisely, as consisting of multiply bonded, linear polymer reinforcements within a silica aerogel matrix. Thus far, several different polymethacrylates (PMAs) have been incorporated into aerogel networks to increase resistance to crushing and to improve other mechanical properties while minimally affecting thermal conductivity and density. The polymethacrylate phases are strongly linked into the silica aerogel networks in these materials. Unlike in other organic/inorganic blended aerogels, the inorganic and organic phases are chemically bonded to each other, by both covalent and hydrogen bonds. In the process for making a silica/polymer alloy aerogel, the covalent bonds are introduced by prepolymerization of the methacrylate monomer with trimethoxysilylpropylmethacrylate, which serves as a phase cross-linker in that it contains both organic and inorganic monomer functional groups and hence acts as a connector between the organic and inorganic phases. Hydrogen bonds are formed between the silanol groups of the inorganic phase and the

  2. Skin penetration of silica microparticles.

    PubMed

    Boonen, J; Baert, B; Lambert, J; De Spiegeleer, B

    2011-06-01

    Knowledge about skin penetration of nano- and microparticles is essential for the development of particle-core drug delivery systems and toxicology. A large number of studies have been devoted to metallic particle penetration. However, little work has been published about the importance of chemical material properties of the particles and the skin penetration effect of the applied formulation. Here, we investigated the penetration of 3 microm silica particles in water and in a 65% ethanolic plant extract on ex vivo human skin using scanning electron microscopy. Contrary to most other microsphere skin studies, we observed for the first time that 3 microm silica particles can penetrate the living epidermis. Moreover, when formulated in the ethanolic medium, particles even reach the dermis. The deviating chemical properties of silica compared to previously investigated microparticles (titanium dioxide, zinc oxide) and confounding effect of the formulation in which the silica microparticles are presented, is thus demonstrated. PMID:21699089

  3. 77 FR 73114 - Draft Written Re-Evaluation for Environmental Impact Statement: T.F. Green Airport, Warwick, RI

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-07

    ... Federal Aviation Administration Draft Written Re-Evaluation for Environmental Impact Statement: T.F. Green... to T.F. Green Draft Written Re-Evaluation'' in the subject line Mail: Richard Doucette, Environmental... England, 16 New England Executive Park, Burlington, MA, 781- 238-7613; Warwick Central Library, 600...

  4. 77 FR 43143 - Limitation on Claims for Judicial Review; Re-Evaluation With Respect to the Willits Bypass...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-23

    ...-evaluations were prepared in order to determine whether a supplemental Environmental Impact Statement (SEIS... INFORMATION: Caltrans conducted two Re-evaluations of the Final Environmental Impact Statement (FEIS) issued... properties, and land use. The purpose of the Re-evaluations was to examine potential environmental...

  5. Psychometric Reevaluation of the Scientific Attitude Inventory-Revised (SAI-II)

    ERIC Educational Resources Information Center

    Lichtenstein, Michael J.; Owen, Steven V.; Blalock, Cheryl L.; Liu, Yan; Ramirez, Kacy A.; Pruski, Linda A.; Marshall, Carolyn E.; Toepperwein, Mary Anne

    2008-01-01

    The central purposes of this study were to review the development and evolution of the Scientific Attitude Inventory (SAI) and then reevaluate the psychometric properties of the revised form of the SAI, the Scientific Attitude Inventory II (SAI-II). The SAI-II was administered to a convenience sample of 543 middle and high school students from…

  6. Reevaluation of the Amsterdam Inventory for Auditory Disability and Handicap Using Item Response Theory

    ERIC Educational Resources Information Center

    Hospers, J. Mirjam Boeschen; Smits, Niels; Smits, Cas; Stam, Mariska; Terwee, Caroline B.; Kramer, Sophia E.

    2016-01-01

    Purpose: We reevaluated the psychometric properties of the Amsterdam Inventory for Auditory Disability and Handicap (AIADH; Kramer, Kapteyn, Festen, & Tobi, 1995) using item response theory. Item response theory describes item functioning along an ability continuum. Method: Cross-sectional data from 2,352 adults with and without hearing…

  7. Never Married Elderly as a Social Type: Re-evaluating Some Images.

    ERIC Educational Resources Information Center

    Rubinstein, Robert L.

    1987-01-01

    Uses data from two studies to reevaluate some images about the never married elderly. Data suggest that never married elderly are not necessarily socially isolated, may experience some loneliness, do not have uniform attitude concerning possibility of marriage, and suffer from the effects of loss in late life. (Author/NB)

  8. Loveless Frump as Hip and Sexy Party Girl: A Reevaluation of the Old-Maid Stereotype.

    ERIC Educational Resources Information Center

    Adams, Katherine C.

    2000-01-01

    Argues for a reevaluation of the old-maid stereotype that will allow professionals in the library and information science (LIS) field to embrace digital technology while remaining mindful of their distinctiveness and recognizing the stereotype as an important part of their collective identity and professional history. (Contains 55 references.)…

  9. 42 CFR 405.213 - Re-evaluation of a device categorization.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 2 2011-10-01 2011-10-01 false Re-evaluation of a device categorization. 405.213 Section 405.213 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES MEDICARE PROGRAM FEDERAL HEALTH INSURANCE FOR THE AGED AND DISABLED Medical Services Coverage Decisions That Relate to Health...

  10. 12 CFR 560.172 - Re-evaluation of real estate owned.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 5 2011-01-01 2011-01-01 false Re-evaluation of real estate owned. 560.172... of real estate owned. A savings association shall appraise each parcel of real estate owned at the... under the particular circumstances. The foregoing requirement shall not apply to any parcel of...

  11. 12 CFR 560.172 - Re-evaluation of real estate owned.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 6 2013-01-01 2012-01-01 true Re-evaluation of real estate owned. 560.172... of real estate owned. A savings association shall appraise each parcel of real estate owned at the... under the particular circumstances. The foregoing requirement shall not apply to any parcel of...

  12. 12 CFR 560.172 - Re-evaluation of real estate owned.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 6 2014-01-01 2012-01-01 true Re-evaluation of real estate owned. 560.172... of real estate owned. A savings association shall appraise each parcel of real estate owned at the... under the particular circumstances. The foregoing requirement shall not apply to any parcel of...

  13. 12 CFR 560.172 - Re-evaluation of real estate owned.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Re-evaluation of real estate owned. 560.172... of real estate owned. A savings association shall appraise each parcel of real estate owned at the... under the particular circumstances. The foregoing requirement shall not apply to any parcel of...

  14. Re-Evaluation Co-Counseling: A Method of Peer Self Help.

    ERIC Educational Resources Information Center

    Rockman, Ilene F.

    The college and university counseling center traditionally employs standard techniques in helping students, faculty, and staff in overcoming problems of mental stress (Berman, 1972). A technique suitable to both individual and group sessions, but rarely utilized is Re-Evaluation Co-Counseling or R.C. For the past twenty years, R.C. has gained an…

  15. 75 FR 49930 - Stakeholder Meeting Regarding Re-Evaluation of Currently Approved Total Coliform Analytical Methods

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-16

    ... Methods AGENCY: Environmental Protection Agency (EPA). ACTION: Notice. SUMMARY: The Environmental...) analytical methods. At these meetings, stakeholders will be given an opportunity to discuss potential elements of a method re-evaluation study, such as developing a reference coliform/non-coliform library...

  16. Reevaluating the Aims of Modern Dance Training in Korea: Toward a Whole Dancer

    ERIC Educational Resources Information Center

    Kim, Na-ye

    2013-01-01

    This study reevaluates modern dance training in Korea and attempts to identify possible improvements. This study is based on the rationale that Korean modern dance training must recover its nature of a holistic connection between body and mind. A qualitative methodology was used to interpret data from in-depth interviews and open-ended…

  17. 34 CFR 602.19 - Monitoring and reevaluation of accredited institutions and programs.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 34 Education 3 2011-07-01 2011-07-01 false Monitoring and reevaluation of accredited institutions and programs. 602.19 Section 602.19 Education Regulations of the Offices of the Department of Education (Continued) OFFICE OF POSTSECONDARY EDUCATION, DEPARTMENT OF EDUCATION THE SECRETARY'S RECOGNITION OF ACCREDITING AGENCIES The Criteria...

  18. 34 CFR 602.19 - Monitoring and reevaluation of accredited institutions and programs.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... institution it has accredited that offers distance education or correspondence education. If any such... 34 Education 3 2012-07-01 2012-07-01 false Monitoring and reevaluation of accredited institutions and programs. 602.19 Section 602.19 Education Regulations of the Offices of the Department...

  19. 34 CFR 602.19 - Monitoring and reevaluation of accredited institutions and programs.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... institution it has accredited that offers distance education or correspondence education. If any such... 34 Education 3 2013-07-01 2013-07-01 false Monitoring and reevaluation of accredited institutions and programs. 602.19 Section 602.19 Education Regulations of the Offices of the Department...

  20. 34 CFR 602.19 - Monitoring and reevaluation of accredited institutions and programs.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 3 2010-07-01 2010-07-01 false Monitoring and reevaluation of accredited institutions and programs. 602.19 Section 602.19 Education Regulations of the Offices of the Department of Education (Continued) OFFICE OF POSTSECONDARY EDUCATION, DEPARTMENT OF EDUCATION THE SECRETARY'S RECOGNITION OF ACCREDITING AGENCIES The Criteria...

  1. 34 CFR 602.19 - Monitoring and reevaluation of accredited institutions and programs.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... institution it has accredited that offers distance education or correspondence education. If any such... 34 Education 3 2014-07-01 2014-07-01 false Monitoring and reevaluation of accredited institutions and programs. 602.19 Section 602.19 Education Regulations of the Offices of the Department...

  2. 34 CFR 300.305 - Additional requirements for evaluations and reevaluations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 2 2010-07-01 2010-07-01 false Additional requirements for evaluations and reevaluations. 300.305 Section 300.305 Education Regulations of the Offices of the Department of Education (Continued) OFFICE OF SPECIAL EDUCATION AND REHABILITATIVE SERVICES, DEPARTMENT OF EDUCATION ASSISTANCE TO STATES FOR THE EDUCATION OF CHILDREN...

  3. Educational Reevaluation, Political Transformation: Québec and Higher Education

    ERIC Educational Resources Information Center

    Unger, Zoe

    2013-01-01

    This paper considers the history of Québec's higher education system and the reforms that have contributed to the role of education in the province. Québec's education system has repeatedly been a site for social and political transformation; most recently, reevaluation of education's role in the province has revealed a tension…

  4. Silica-volatile interaction and the geological cause of the Xuan Wei lung cancer epidemic

    SciTech Connect

    David J. Large; Shona Kelly; Baruch Spiro; Linwei Tian; Longyi Shao; Robert Finkelman; Mingquan Zhang; Chris Somerfield; Steve Plint; Yasmin Ali; Yiping Zhou

    2009-12-01

    Parts of Xuan Wei County, Yunnan Province, China have the highest known lung cancer mortality in nonsmoking women. This high mortality displays a clear spatial relationship to the mines producing coal from the uppermost Permian. Geochemical, petrographic, and grain size analyses were undertaken on a set of coal samples from Xuan Wei. Results demonstrate that the single geochemical property that makes this coal unusual is its high concentration of quartz (13.5 wt %) of which 35-55% occurs as < 10 {mu}m grains. We propose the potential for silica-volatile interaction (PSVI) as a new method for assessing the combined influence of silica and volatile organic matter and use this as a basis for re-evaluating existing ecological data. Published lung cancer mortality values are more strongly correlated with PSVI values for Xuan Wei coal than with volatiles or silica alone and the PSVI values measured are distinct from those of other coals. Finally we propose that the localization of this epidemic to Xuan Wei results from enhanced weathering of the local Emeishan basalts as a consequence of geochemical perturbations at the Permo-Triassic Boundary.

  5. Simulation of Peptide Binding to Silica and Silica Mineralization

    NASA Astrophysics Data System (ADS)

    Emami, F. S.; Heinz, H.; Berry, R. J.; Varshney, V.; Farmer, B. L.; Naik, R. R.; Patwardhan, S. V.; Perry, C. C.

    2009-03-01

    The purpose of this study is to identify the nature of the interaction of peptides with silica surfaces and their effect on mineralization. Classical force fields (CVFF, PCFF) have been extended for silica aiming at the computation of surface properties in quantitative agreement with experiment, taking explicitly into account water molecules, pH, and surface coverage with peptides. We focus on the interaction of five short peptides (pep1, pep4, 82-4, H4, R5) identified by biopanning with regular and amorphous silica surfaces (Q3 and Q2) to understand the relation between peptide sequence and affinity to the surface. Results of the atomistic molecular dynamics simulation indicate adsorption energies, binding constants and conformational changes upon adsorption. The comparison of NMR chemical shifts in solution and on the surface in computation and experiment further aids in understanding the mechanism of binding.

  6. [The evaluation of biological effects of exposure to respirable crystalline silica in building industry].

    PubMed

    Pira, E; Piolatto, P G

    2012-01-01

    The building industry entails the exposure to Respirable Crystalline Silica (RCS), though there is a large variability among different sectors. The environmental values reported for the current conditions seem to be relatively low. For example the mean exposure estimated by IOM for all industrial sectors in the EU is 0.07 mg/m3. There are few studies in the building sector which show similar values. This is obviously not representative of past exposure. Moreover, the problems of sampling and analysis techniques are still at issue. The well known effect of RCS exposure is silicosis. The carcinogenicity of RCS is still under debate, especially regarding the question of whether RCS is carcinogenic "per se" or whether the risk of developing lung cancer is mediated by silicosis. Although the IARC includes RCS in the Group I (human carcinogen), the reference should be the CLP regulation, of which carcinogen definition criteria allow to state that today there are not sufficient data to classify RCS as a carcinogen and that it seems more appropriate to include RCS in different STOT.RE categories. This is valid for building industry as well as for the other industrial sectors. In Italy the recommended exposure limit is the ACGIH value of 0.025 mg/m3. At EU level it is still debated which is the best choice, based on cost/benefits evaluation, among the following limit values: 0.2, 0.1 and 0.05 respectively. The authors obviously believe that the most protective value should be adopted. PMID:23213807

  7. Surface modification of silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Ranjan, Rajesh

    Surface modification of nanosized silica particles by polymer grafting is gaining attention. This can be attributed to the fact that it provides a unique opportunity to engineer the interfacial properties of these modified particles; at the same time the mechanical and thermal properties of the polymers can be improved. Controlled free radical polymerization is a versatile technique which affords control over molecular weight, molecular weight distribution, architecture and functionalities of the resulting polymer. Three commonly used controlled free radical polymerizations include nitroxide-mediated polymerization (NMP), atom transfer radical polymerization (ATRP) and reversible addition fragmentation transfer (RAFT) polymerization. ATRP and RAFT polymerization were explored in order to modify the silica surface with well-defined polymer brushes. A novel click-functionalized RAFT chain transfer agent (RAFT CTA) was synthesized which opened up the possibility of using RAFT polymerization and click chemistry together in surface modification. Using this RAFT CTA, the surface of silica nanoparticles was modified with polystyrene and polyacrylamide brushes via the "grafting to" approach. Both tethered polystyrene and polyacrylamide chains were found in the brush regime. The combination of ATRP and click chemistry was also explored for surface modification. A combination of RAFT polymerization and click chemistry was also studied to modify the surface via the "grafting from" approach. Our strategy included the (1) "grafting from" approach for brush formation (2) facile click reaction to immobilize the RAFT agent (3) synthesis of R-supported chain transfer agent and (4) use of the more active trithiocarbonate RAFT agent. Grafting density obtained by this method was significantly higher than reported values in the literature. Polystyrene (PS) grafted silica nanoparticles were also prepared by a tandem process that simultaneously employs reversible addition fragmentation

  8. Precipitated silica as flow regulator.

    PubMed

    Müller, Anne-Kathrin; Ruppel, Joanna; Drexel, Claus-Peter; Zimmermann, Ingfried

    2008-08-01

    Flow regulators are added to solid pharmaceutical formulations to improve the flow properties of the powder mixtures. The primary particles of the flow regulators exist in the form of huge agglomerates which are broken down into smaller aggregates during the blending process. These smaller aggregates adsorb at the surface of the solid's grains and thus diminish attractive Van-der-Waals-forces by increasing the roughness of the host's surface. In most cases amorphous silica is used as flow additive but material properties like particle size or bond strength influence the desagglomeration tendency of the agglomerates and thus the flow regulating potency of each silica. For some silica types we will show that the differences in their flow regulating potency are due to the rate and extent by which they are able to cover the surface of the host particles. Binary powder mixtures consisting of a pharmaceutical excipient and an added flow regulator were blended in a Turbula mixer for a defined period of time. As pharmaceutical excipient corn starch was used. The flow regulators were represented by a selection of amorphous silicon dioxide types like a commercial fumed silica and various types of SIPERNAT precipitated silica provided by Evonik-Degussa GmbH, Hanau, Germany. Flowability parameters of the mixtures were characterized by means of a tensile strength tester. The reduction of tensile strength with the blending time can be correlated with an increase in fragmentation of the flow regulator. PMID:18595668

  9. Exposure to crystalline silica in abrasive blasting operations where silica and non-silica abrasives are used.

    PubMed

    Radnoff, Diane L; Kutz, Michelle K

    2014-01-01

    Exposure to respirable crystalline silica is a hazard common to many industries in Alberta but particularly so in abrasive blasting. Alberta occupational health and safety legislation requires the consideration of silica substitutes when conducting abrasive blasting, where reasonably practicable. In this study, exposure to crystalline silica during abrasive blasting was evaluated when both silica and non-silica products were used. The crystalline silica content of non-silica abrasives was also measured. The facilities evaluated were preparing metal products for the application of coatings, so the substrate should not have had a significant contribution to worker exposure to crystalline silica. The occupational sampling results indicate that two-thirds of the workers assessed were potentially over-exposed to respirable crystalline silica. About one-third of the measurements over the exposure limit were at the work sites using silica substitutes at the time of the assessment. The use of the silica substitute, by itself, did not appear to have a large effect on the mean airborne exposure levels. There are a number of factors that may contribute to over-exposures, including the isolation of the blasting area, housekeeping, and inappropriate use of respiratory protective equipment. However, the non-silica abrasives themselves also contain silica. Bulk analysis results for non-silica abrasives commercially available in Alberta indicate that many contain crystalline silica above the legislated disclosure limit of 0.1% weight of silica per weight of product (w/w) and this information may not be accurately disclosed on the material safety data sheet for the product. The employer may still have to evaluate the potential for exposure to crystalline silica at their work site, even when silica substitutes are used. Limited tests on recycled non-silica abrasive indicated that the silica content had increased. Further study is required to evaluate the impact of product recycling

  10. Staged re-evaluation of non-culprit lesions in ST segment elevation myocardial infarction: a retrospective study

    PubMed Central

    Thim, Troels; Egholm, Gro; Olesen, Kevin Kris Warnakula; Kaltoft, Anne; Terkelsen, Christian Juhl; Krusell, Lars Romer; Kristensen, Steen Dalby; Bøtker, Hans Erik; Christiansen, Evald Høj; Maeng, Michael

    2016-01-01

    Objective It remains unknown whether complete revascularisation is optimally performed in patients with ST segment elevation myocardial infarction (STEMI) during the index or at staged procedures. The aims of this study were to quantify the number of primary percutaneous coronary intervention (PCI) procedures in which non-culprit lesions needed further evaluation, to determine the consequence of the re-evaluation and to quantify adverse cardiac events during the waiting time for re-evaluation and intervention. Methods The study was observational and retrospective and included all patients with STEMI treated with primary PCI during 1 year at our centre. Results Among the 507 patients with STEMI, 374 were considered sufficiently treated with culprit lesion PCI only. Complete primary multivessel revascularisation was performed in 11 patients. Non-culprit lesion re-evaluation was planned for 122 patients (24%). Of these 122 patients, 3 patients died during their index admission. Follow-up data were not available for 3 patients. Among the 116 patients, 187 non-culprit lesions were re-evaluated and 77 patients (66.4%) underwent revascularisation with treatment of 119 lesions (63.3%). Re-evaluation was performed after a median of 30 days (25th centile: 9 days, 75th centile: 35 days). During the waiting time for re-evaluation, two patients underwent a new primary PCI due to stent thrombosis of the index culprit lesion. Conclusions Staged re-evaluation of non-culprit lesions observed in patients with STEMI was required in 24% of a primary PCI cohort. Intervention was performed in 66.4% of patients scheduled for re-evaluation. We observed no adverse events related to the non-culprit lesions during the waiting time for a staged re-evaluation or intervention. PMID:27403331

  11. Admicellar polymerization of precipated silica

    SciTech Connect

    Reynolds, J.L.; Grady, B.P.; Harwell, J.H.

    1996-10-01

    The tendency of a surfactant molecule to adsorb at a solid-liquid interface is the basis for an in situ surface modification process, termed admicellar polymerization. The four-step admicellar polymerization process includes: (1) adsorption of surfactant at the solid-liquid interface, (2) adsolubilization of monomer into the surfactant bilayer, (3) polymerization using free-radical initiators and heat, (4) removal of excess surfactant to expose the polymer modified surface. The process is used to apply polymer to precipitated silica to enhance the compatibility of the silica when added to filled rubber. The adsorption isotherms were first determined for particular surfactant/silica combinations to find the surfactant concentration that would sufficiently adsolubilize the monomer, while remaining below the critical micelle concentration. A series of experiments were then devised for the polymerization reactions in which the surfactant and monomer amounts were varied over three levels to establish the optimal combination.

  12. 21 CFR 584.700 - Hydrophobic silicas.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...: (i) Amorphous fumed hydrophobic silica: Not less than 99.0 percent silicon dioxide after ignition... dichlorodimethylsilane. (ii) Precipated hydrophobic silica: Not less than 94.0 percent silicon dioxide after...

  13. Physisorbed Water on Silica at Mars Temperatures

    NASA Technical Reports Server (NTRS)

    Sutter, B.; Sriwatanapongse, W.; Quinn, R.; Klug, C.; Zent, A.

    2002-01-01

    The usefulness of nuclear magnetic resonance spectroscopy in probing water interactions on silica at Mars temperatures is discussed. Results indicate that two types of water occur with silica at Mars temperatures. Additional information is contained in the original extended abstract.

  14. Optothermal nonlinearity of silica aerogel

    NASA Astrophysics Data System (ADS)

    Braidotti, Maria Chiara; Gentilini, Silvia; Fleming, Adam; Samuels, Michiel C.; Di Falco, Andrea; Conti, Claudio

    2016-07-01

    We report on the characterization of silica aerogel thermal optical nonlinearity, obtained by z-scan technique. The results show that typical silica aerogels have nonlinear optical coefficient similar to that of glass (≃10-12 m2/W), with negligible optical nonlinear absorption. The nonlinear coefficient can be increased to values in the range of 10-10 m2/W by embedding an absorbing dye in the aerogel. This value is one order of magnitude higher than that observed in the pure dye and in typical highly nonlinear materials like liquid crystals.

  15. Silica Precursors Derived From TEOS

    NASA Technical Reports Server (NTRS)

    Philipp, Warren H.

    1993-01-01

    Two high-char-yield polysiloxane polymers developed. Designated as TEOS-A and TEOS-B with silica char yields of 55% and 22%, respectively. These free-flowing polymers are Newtonium liquids instead of thick gels. Easily synthesized by controlled hydrolysis of inexpensive tetraethoxysilane (TEOS). Adhesive properties of TEOS-A suggest its use as binder for fabrication of ceramic articles from oxide powders. Less-viscous and more-fluid lower-molecular-weight TEOS-B used to infiltrate already-formed porous ceramic compacts to increase densities without effecting shrinkage. Also used as paint to coat substrate with silica, and to make highly pure silicate powders.

  16. The properties of silica-gelatin composites

    NASA Astrophysics Data System (ADS)

    Stavinskaya, O. N.; Laguta, I. V.

    2010-06-01

    Silica-gelatin composites with various silica-to-gelatin ratios were obtained. The influence of high-dispersity silica on the swelling of composites in water and desorption of pyridoxine and thiamine vitamins incorporated into the material was studied. The addition of silica to gelatin was shown to increase the time of the dissolution of the materials in aqueous medium and decelerate the desorption of vitamins.

  17. Removal of dissolved and colloidal silica

    DOEpatents

    Midkiff, William S.

    2002-01-01

    Small amorphous silica particles are used to provide a relatively large surface area upon which silica will preferentially adsorb, thereby preventing or substantially reducing scaling caused by deposition of silica on evaporative cooling tower components, especially heat exchange surfaces. The silica spheres are contacted by the cooling tower water in a sidestream reactor, then separated using gravity separation, microfiltration, vacuum filtration, or other suitable separation technology. Cooling tower modifications for implementing the invention process have been designed.

  18. Determination of 1,3-butadiene in workplace air: reevaluation of NIOSH (National Institute for Occupational Safety and Health) Method S91 and development of NIOSH Method 1024

    SciTech Connect

    Lunsford, R.A.; Gagnon, Y.T.

    1988-08-24

    NIOSH Method S91 for the determination of 1,3-butadiene in air was reevaluated, and a new method was developed. Limitations to Method S91 included the fact that the lower quantitation limit appeared to be about 3.4 parts per million (ppm) and the packed-column gas-chromatographic analysis was subject to interference. The new method developed, Method 1024, employed collection on tandem coconut-shell charcoal tubes, desorption with methylene chloride, and high-resolution gas-chromatographic analysis. Evaluation of Method 1024 indicated that it should be useful for determining full-shift time-weighted average exposures in humid air at concentrations ranging from 0.4 to 10 ppm. The sampler's capacity should permit quantitation of levels up to 100 ppm if desorbed samples are diluted so that they fall in the calibration range. In the chromatographic process, the combination of backflushable precolumn and aluminum oxide fused-silica capillary analytical columns offered the advantages of enhanced sensitivity enabling detection down to 0.005 ppm in 25 liters, and enhanced selectivity, limiting the need for confirmatory techniques.

  19. Comparison of silica-core optical fibers

    NASA Astrophysics Data System (ADS)

    McCann, Brian P.

    1991-07-01

    Silica-core optical fibers have become a standard vehicle to remotely deliver high-power laser energy from surgical lasers operating between 200 and 2400 nm. The three primary types of silica-core fibers: plastic-clad; hard-clad; and silica-clad; are discussed. The performance advantages of each are addressed and actual general-surgery medical applications are provided.

  20. Re-evaluating the northeastern Minnesota moose decline and the role of wolves

    USGS Publications Warehouse

    Mech, L. David; Fieberg, John

    2014-01-01

    We re-evaluated findings from Lenarz et al. (2009) that adult moose (Alces alces) survival in northeastern Minnesota was related to high January temperatures and that predation by wolves (Canis lupus) played a minor role. We found significant inverse relationships between annual wolf numbers in part of the moose range and various moose demographics from 2003 to 2013 that suggested a stronger role of wolves than heretofore believed. To re-evaluate the temperature findings, we conducted a simulation study, mimicking the approach taken by Lenarz et al. (2009), to explore the potential for concluding a significant relationship exists between temperature and survival, when no association exists. We found that the high R2s and low probabilities associated with the regression models in Lenarz et al. (2009) should be viewed cautiously in light of the large number of fitted models (m = 45) and few observations (n = 6 for each of 5 response variables).

  1. Reevaluating nuclear safety and security in a post 9/11 era.

    SciTech Connect

    Booker, Paul M.; Brown, Lisa M.

    2005-07-01

    This report has the following topics: (1) Changing perspectives on nuclear safety and security; (2) Evolving needs in a post-9/11 era; (3) Nuclear Weapons--An attractive terrorist target; (4) The case for increased safety; (5) Evolution of current nuclear weapons safety and security; (6) Integrated surety; (7) The role of safety and security in enabling responsiveness; (8) Advances in surety technologies; and (9) Reevaluating safety.

  2. Orphan caribou, Rangifer tarandus, calves: A re-evaluation of overwinter survival data

    USGS Publications Warehouse

    Joly, Kyle

    2000-01-01

    Low sample size and high variation within populations reduce power of statistical tests. These aspects of statistical power appear to have affected an analysis comparing overwinter survival rates of non-orphan and orphan Caribou (Rangifer tarandus) calves by an earlier study for the Porcupine Caribou Herd. A re-evaluation of the data revealed that conclusions about a lack of significant difference in the overwinter survival rates between orphan and non-orphan calves were premature.

  3. Silica optical fibers: technology update

    NASA Astrophysics Data System (ADS)

    Krohn, David A.; McCann, Brian P.

    1995-05-01

    Silica-core optical fibers have long been the standard delivery medium for medical laser delivery systems. Their high strength, excellent flexibility, and low cost continue to make them the fiber of choice for systems operating from 300 to 2200 nm. An overview of the current fiber constructions available to the industry is reviewed. Silicone-clad fibers, hard- fluoropolymer clad fibers and silica-clad fibers are briefly compared in terms of mechanical and optical properties. The variety of fiber coatings available is also discussed. A significant product development of silica fiber delivery systems has been in side-firing laser delivery systems for Urology. These devices utilize silica-core fibers to project the laser energy at a substantial lateral angle to the conventional delivery system, typically 40 to 100 degrees off axis. Many unique distal tips have been designed to meet the needs of this potentially enormous application. There are three primary technologies employed in side-firing laser delivery systems: reflection off of an attached medium; reflection within an angle-polished fiber through total internal reflection; and reflection from both an angle-polished fiber and an outside medium. Each technology is presented and compared on the basis of operation modality, transmission efficiency, and power-handling performance.

  4. The Phagocytosis and Toxicity of Amorphous Silica

    PubMed Central

    Costantini, Lindsey M.; Gilberti, Renée M.; Knecht, David A.

    2011-01-01

    Background Inhalation of crystalline silica is known to cause an inflammatory reaction and chronic exposure leads to lung fibrosis and can progress into the disease, silicosis. Cultured macrophages bind crystalline silica particles, phagocytose them, and rapidly undergo apoptotic and necrotic death. The mechanism by which particles are bound and internalized and the reason particles are toxic is unclear. Amorphous silica has been considered to be a less toxic form, but this view is controversial. We compared the uptake and toxicity of amorphous silica to crystalline silica. Methodology/Principal Findings Amorphous silica particles are phagocytosed by macrophage cells and a single internalized particle is capable of killing a cell. Fluorescent dextran is released from endo-lysosomes within two hours after silica treatment and Caspase-3 activation occurs within 4 hours. Interestingly, toxicity is specific to macrophage cell lines. Other cell types are resistant to silica particle toxicity even though they internalize the particles. The large and uniform size of the spherical, amorphous silica particles allowed us to monitor them during the uptake process. In mCherry-actin transfected macrophages, actin rings began to form 1-3 minutes after silica binding and the actin coat disassembled rapidly following particle internalization. Pre-loading cells with fluorescent dextran allowed us to visualize the fusion of phagosomes with endosomes during internalization. These markers provided two new ways to visualize and quantify particle internalization. At 37°C the rate of amorphous silica internalization was very rapid regardless of particle coating. However, at room temperature, opsonized silica is internalized much faster than non-opsonized silica. Conclusions/Significance Our results indicate that amorphous and crystalline silica are both phagocytosed and both toxic to mouse alveolar macrophage (MH-S) cells. The pathway leading to apoptosis appears to be similar in both

  5. [Research about re-evaluation of screening of traditonal Chinese medicine symptoms item of post-marketing medicine Xuezhikang].

    PubMed

    He, Wei; Xie, Yanming; Wang, Yongyan

    2011-10-01

    The purpose of post-marketing Chinese medicine re-evaluation is to identify Chinese medicine clinical indications, while designing scientific and rational of Chinese medicine symptoms items are important to the result of symptoms re-evaluation. This study give screening of traditional Chinese medicine(TCM) symptoms item of post-marketing medicine Xuezhikang re-evaluation as example that reference to principle dyslipidemia clinical research, academic dissertations, Xuezhikang directions, clinical expert practice experience etc. while standardization those symptom names and screening 41 dyslipidemia common symptoms. Furthermore, this paper discuss about the accoerdance and announcements when screening symptoms item, so as to providing a research thread to manufacture PRO chart for post-marketing medicine re-evaluation. PMID:22292395

  6. Status report and FY95 plans -- Re-evaluation of NOAA Dobson spectrophotometer total ozone data. 1994 annual report

    SciTech Connect

    1994-12-31

    The goal of this project was to re-evaluate NOAA/CMDL Dobson spectrophotometer total ozone data during FY94 from the stations Haute Provence, France; Lauder, New Zealand; Perth, Australia; and Poker Flat, Alaska and the Umkehr data from Boulder, Colorado and Mauna Loa, Hawaii. During the second year the authors planned to re-evaluate total ozone data from Byrd, Hallett and South Pole, Antarctica; Fairbanks, Alaska; Puerto Montt, Chile; Huancayo, Peru and Umkehr data from Huancayo.

  7. Uranium incorporation into amorphous silica.

    PubMed

    Massey, Michael S; Lezama-Pacheco, Juan S; Nelson, Joey M; Fendorf, Scott; Maher, Kate

    2014-01-01

    High concentrations of uranium are commonly observed in naturally occurring amorphous silica (including opal) deposits, suggesting that incorporation of U into amorphous silica may represent a natural attenuation mechanism and promising strategy for U remediation. However, the stability of uranium in opaline silicates, determined in part by the binding mechanism for U, is an important factor in its long-term fate. U may bind directly to the opaline silicate matrix, or to materials such as iron (hydr)oxides that are subsequently occluded within the opal. Here, we examine the coordination environment of U within opaline silica to elucidate incorporation mechanisms. Precipitates (with and without ferrihydrite inclusions) were synthesized from U-bearing sodium metasilicate solutions, buffered at pH ∼ 5.6. Natural and synthetic solids were analyzed with X-ray absorption spectroscopy and a suite of other techniques. In synthetic amorphous silica, U was coordinated by silicate in a double corner-sharing coordination geometry (Si at ∼ 3.8-3.9 Å) and a small amount of uranyl and silicate in a bidentate, mononuclear (edge-sharing) coordination (Si at ∼ 3.1-3.2 Å, U at ∼ 3.8-3.9 Å). In iron-bearing synthetic solids, U was adsorbed to iron (hydr)oxide, but the coordination environment also contained silicate in both edge-sharing and corner-sharing coordination. Uranium local coordination in synthetic solids is similar to that of natural U-bearing opals that retain U for millions of years. The stability and extent of U incorporation into opaline and amorphous silica represents a long-term repository for U that may provide an alternative strategy for remediation of U contamination. PMID:24984107

  8. Adsorption of organic molecules on silica surface.

    PubMed

    Parida, Sudam K; Dash, Sukalyan; Patel, Sabita; Mishra, B K

    2006-09-13

    The adsorption behaviour of various organic adsorbates on silica surface is reviewed. Most of the structural information on silica is obtained from IR spectral data and from the characteristics of water present at the silica surface. Silica surface is generally embedded with hydroxy groups and ethereal linkages, and hence considered to have a negative charged surface prone to adsorption of electron deficient species. Adsorption isotherms of the adsorbates delineate the nature of binding of the adsorbate with silica. Aromatic compounds are found to involve the pi-cloud in hydrogen bonding with silanol OH group during adsorption. Cationic and nonionic surfactants adsorb on silica surface involving hydrogen bonding. Sometimes, a polar part of the surfactants also contributes to the adsorption process. Styryl pyridinium dyes are found to anchor on silica surface in flat-on position. On modification of the silica by treating with alkali, the adsorption behaviour of cationic surfactant or polyethylene glycol changes due to change in the characteristics of silica or modified silica surface. In case of PEG-modified silica, adsolubilization of the adsorbate is observed. By using a modified adsorption equation, hemimicellization is proposed for these dyes. Adsorptions of some natural macromolecules like proteins and nucleic acids are investigated to study the hydrophobic and hydrophilic binding sites of silica. Artificial macromolecules like synthetic polymers are found to be adsorbed on silica surface due to the interaction of the multifunctional groups of the polymers with silanols. Preferential adsorption of polar adsorbates is observed in case of adsorbate mixtures. When surfactant mixtures are considered to study competitive adsorption on silica surface, critical micelle concentration of individual surfactant also contributes to the adsorption isotherm. The structural study of adsorbed surface and the thermodynamics of adsorption are given some importance in this review

  9. Organically Modified Silicas on Metal Nanowires

    PubMed Central

    2010-01-01

    Organically modified silica coatings were prepared on metal nanowires using a variety of silicon alkoxides with different functional groups (i.e., carboxyl groups, polyethylene oxide, cyano, dihydroimidazole, and hexyl linkers). Organically modified silicas were deposited onto the surface of 6-μm-long, ∼300-nm-wide, cylindrical metal nanowires in suspension by the hydrolysis and polycondensation of silicon alkoxides. Syntheses were performed at several ratios of tetraethoxysilane to an organically modified silicon alkoxide to incorporate desired functional groups into thin organosilica shells on the nanowires. These coatings were characterized using transmission electron microscopy, X-ray photoelectron spectroscopy, and infrared spectroscopy. All of the organically modified silicas prepared here were sufficiently porous to allow the removal of the metal nanowire cores by acid etching to form organically modified silica nanotubes. Additional functionality provided to the modified silicas as compared to unmodified silica prepared using only tetraethoxysilane precursors was demonstrated by chromate adsorption on imidazole-containing silicas and resistance to protein adsorption on polyethyleneoxide-containing silicas. Organically modified silica coatings on nanowires and other nano- and microparticles have potential application in fields such as biosensing or nanoscale therapeutics due to the enhanced properties of the silica coatings, for example, the prevention of biofouling. PMID:20715881

  10. Synthesis of mesoporous silica nanoparticles.

    PubMed

    Wu, Si-Han; Mou, Chung-Yuan; Lin, Hong-Ping

    2013-05-01

    Good control of the morphology, particle size, uniformity and dispersity of mesoporous silica nanoparticles (MSNs) is of increasing importance to their use in catalyst, adsorption, polymer filler, optical devices, bio-imaging, drug delivery, and biomedical applications. This review discusses different synthesis methodologies to prepare well-dispersed MSNs and hollow silica nanoparticles (HSNs) with tunable dimensions ranging from a few to hundreds of nanometers of different mesostructures. The methods include fast self-assembly, soft and hard templating, a modified Stöber method, dissolving-reconstruction and modified aerogel approaches. In practical applications, the MSNs prepared by these methods demonstrate good potential for use in high-performance catalysis, antireflection coating, transparent polymer-MSNs nanocomposites, drug-release and theranostic systems. PMID:23403864

  11. Gain functionalization of silica microresonators.

    PubMed

    Yang, Lan; Vahala, K J

    2003-04-15

    Erbium-doped solgel films are applied to the surface of silica microspheres to create low-threshold microactivity lasers. This gain functionalization can be applied by use of a number of different dopants, thereby extending the wavelength range of this class of device. Also, by varying the doping concentration and thickness of the applied solgel layer, one can vary the laser dynamics so that both continuous-wave and pulsating modes of operation are possible. PMID:12703910

  12. Silica exposure and systemic vasculitis.

    PubMed Central

    Mulloy, Karen B

    2003-01-01

    Work in Department of Energy (DOE) facilities has exposed workers to multiple toxic agents leading to acute and chronic diseases. Many exposures were common to numerous work sites. Exposure to crystalline silica was primarily restricted to a few facilities. I present the case of a 63-year-old male who worked in DOE facilities for 30 years as a weapons testing technician. In addition to silica, other workplace exposures included beryllium, various solvents and heavy metals, depleted uranium, and ionizing radiation. In 1989 a painful macular skin lesion was biopsied and diagnosed as leukocytoclastic vasculitis. By 1992 he developed gross hematuria and dyspnea. Blood laboratory results revealed a serum creatinine concentration of 2.1 mg/dL, ethrythrocyte sedimentation rate of 61 mm/hr, negative cANCA (antineutrophil cytoplasmic antibody cytoplasmic pattern), positive pANCA (ANCA perinuclear pattern), and antiglomerular basement membrane negative. Renal biopsy showed proliferative (crescentric) and necrotizing glomerulonephritis. The patient's diagnoses included microscopic polyangiitis, systemic necrotizing vasculitis, leukocytoclastic vasculitis, and glomerulonephritis. Environmental triggers are thought to play a role in the development of an idiopathic expression of systemic autoimmune disease. Crystalline silica exposure has been linked to rheumatoid arthritis, scleroderma, systemic lupus erythematosus, rapidly progressive glomerulonephritis and some of the small vessel vasculitides. DOE workers are currently able to apply for compensation under the federal Energy Employees Occupational Illness Compensation Program (EEOICP). However, the only diseases covered by EEOICP are cancers related to radiation exposure, chronic beryllium disease, and chronic silicosis. PMID:14644669

  13. Non-occupational exposure to silica dust

    PubMed Central

    Bhagia, L. J.

    2012-01-01

    Occupational exposure to silica occurs at workplaces in factories like quartz crushing facilities (silica flour milling), agate, ceramic, slate pencil, glass, stone quarries and mines, etc., Non-occupational exposure to silica dust can be from industrial sources in the vicinity of the industry as well as non-industrial sources. Recently, public concern regarding non-occupational or ambient exposure to crystalline silica has emerged making it important to gather information available on non-occupational exposures to silica dust and non-occupational silicosis. This paper reviews various non-occupational exposures reported in literature including some studies by the author. Methodology used in assessment of non-occupational exposures, standards for non-occupational exposures to silica dust and indirect estimation of cumulative risk % are also discussed. PMID:23776316

  14. Silica Extraction at Mammoth Lakes, California

    SciTech Connect

    Bourcier, W; Ralph, W; Johnson, M; Bruton, C; Gutierrez, P

    2006-06-07

    The purpose of this project is to develop a cost-effective method to extract marketable silica (SiO{sub 2}) from fluids at the Mammoth Lakes, California geothermal power plant. Silica provides an additional revenue source for the geothermal power industry and therefore lowers the costs of geothermal power production. The use of this type of ''solution mining'' to extract resources eliminates the need for acquiring these resources through energy intensive and environmentally damaging mining technologies. We have demonstrated that both precipitated and colloidal silica can be produced from the geothermal fluids at Mammoth Lakes by first concentrating the silica to over 600 ppm using reverse osmosis (RO). The RO permeate can be used in evaporative cooling at the plant; the RO concentrate is used for silica and potentially other resource extraction (Li, Cs, Rb). Preliminary results suggest that silica recovery at Mammoth Lakes could reduce the cost of geothermal electricity production by 1.0 cents/kWh.

  15. Characterization of diatomaceous silica by Raman spectroscopy.

    PubMed

    Yuan, P; He, H P; Wu, D Q; Wang, D Q; Chen, L J

    2004-10-01

    The network characteristic of a selection of diatomaceous silica derived from China has been investigated using Raman spectroscopy. Before any thermal treatment of the sample, two prominent bands of 607 and circa 493 cm(-1) are resolved in the Raman spectra of diatomaceous silica, corresponding to the (SiO)3-ring breathing mode of D2-line and the O3SiOH tetrahedral vibration mode of D1-line, respectively. This is more similar to the pyrogenic silica rather than the silica gel. For the latter, to obtain a (SiO)3-ring, the sample must be heated between 250 and 450 degrees C. Significant difference is also found between the diatomaceous silica and other natural silicas, e.g. in the Raman spectra of sedimentary and volcanic opals, neither D1 nor D2 band is detected in previous reports. PMID:15350933

  16. Characterization of diatomaceous silica by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Yuan, P.; He, H. P.; Wu, D. Q.; Wang, D. Q.; Chen, L. J.

    2004-10-01

    The network characteristic of a selection of diatomaceous silica derived from China has been investigated using Raman spectroscopy. Before any thermal treatment of the sample, two prominent bands of 607 and circa 493 cm -1 are resolved in the Raman spectra of diatomaceous silica, corresponding to the (SiO) 3-ring breathing mode of D 2-line and the O 3SiOH tetrahedral vibration mode of D 1-line, respectively. This is more similar to the pyrogenic silica rather than the silica gel. For the latter, to obtain a (SiO) 3-ring, the sample must be heated between 250 and 450 °C. Significant difference is also found between the diatomaceous silica and other natural silicas, e.g. in the Raman spectra of sedimentary and volcanic opals, neither D 1 nor D 2 band is detected in previous reports.

  17. Sealed silica pressure ampoules for crystal growth

    NASA Technical Reports Server (NTRS)

    Holland, L. R.

    1984-01-01

    The properties of vitreous silica and the mechanics of thick walled pressure vessels are reviewed with regard to the construction of sealed silica crucibles such as are used in the growth of mercury-cadmium telluride crystals. Data from destructive rupture tests are reported, failure modes discussed, and recommendations for design given. Ordinary commercial clear vitreous silica from flame fused quartz can withstand a surface stress of 20 MPa or more in this application.

  18. Process for preparing polymer reinforced silica aerogels

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann B. (Inventor); Capadona, Lynn A. (Inventor)

    2011-01-01

    Process for preparing polymer-reinforced silica aerogels which comprises a one-pot reaction of at least one alkoxy silane in the presence of effective amounts of a polymer precursor to obtain a silica reaction product, the reaction product is gelled and subsequently subjected to conditions that promotes polymerization of the precursor and then supercritically dried to obtain the polymer-reinforced monolithic silica aerogels.

  19. Mesoporous Silica: A Suitable Adsorbent for Amines

    PubMed Central

    2009-01-01

    Mesoporous silica with KIT-6 structure was investigated as a preconcentrating material in chromatographic systems for ammonia and trimethylamine. Its adsorption capacity was compared to that of existing commercial materials, showing its increased adsorption power. In addition, KIT-6 mesoporous silica efficiently adsorbs both gases, while none of the employed commercial adsorbents did. This means that KIT-6 Mesoporous silica may be a good choice for integrated chromatography/gas sensing micro-devices. PMID:20628459

  20. Re-evaluation of classical prognostic factors in resectable ductal adenocarcinoma of the pancreas.

    PubMed

    Åkerberg, Daniel; Ansari, Daniel; Andersson, Roland

    2016-07-28

    Pancreatic ductal adenocarcinoma carries a poor prognosis with annual deaths almost matching the reported incidence rates. Surgical resection offers the only potential cure. Yet, even among patients that undergo tumor resection, recurrence rates are high and long-term survival is scarce. Various tumor-related factors have been identified as predictors of survival after potentially curative resection. These factors include tumor size, lymph node disease, tumor grade, vascular invasion, perineural invasion and surgical resection margin. This article will re-evaluate the importance of these factors based on recent publications on the topic, with potential implications for treatment and outcome in patients with pancreatic cancer. PMID:27605878

  1. A re-evaluation of Scinaia (Nemaliales, Rhodophyta) in the Azores

    NASA Astrophysics Data System (ADS)

    León-Cisneros, K.; Riosmena-Rodríguez, R.; Neto, A. I.

    2011-06-01

    The genus Scinaia in the Azores is re-evaluated based on historical and recent collections. A combination of morphological and anatomical diagnostic characters was used for species segregation, and a key for Azorean species determination is presented. Anatomical information associated to the hair development is described for the first time for the genus. The occurrence of S. furcellata and S. interrupta is confirmed for the archipelago. The presence of S. acuta is reported for the first time in the Azores, representing a spread from Australia to the N-Atlantic and specifically into the Macaronesian region. Its occurrence in the archipelago and the Canaries is discussed as a possible introduction.

  2. Source-term reevaluation for US commercial nuclear power reactors: a status report

    SciTech Connect

    Herzenberg, C.L.; Ball, J.R.; Ramaswami, D.

    1984-12-01

    Only results that had been discussed publicly, had been published in the open literature, or were available in preliminary reports as of September 30, 1984, are included here. More than 20 organizations are participating in source-term programs, which have been undertaken to examine severe accident phenomena in light-water power reactors (including the chemical and physical behavior of fission products under accident conditions), update and reevaluate source terms, and resolve differences between predictions and observations of radiation releases and related phenomena. Results from these source-term activities have been documented in over 100 publications to date.

  3. Re-evaluation of classical prognostic factors in resectable ductal adenocarcinoma of the pancreas

    PubMed Central

    Åkerberg, Daniel; Ansari, Daniel; Andersson, Roland

    2016-01-01

    Pancreatic ductal adenocarcinoma carries a poor prognosis with annual deaths almost matching the reported incidence rates. Surgical resection offers the only potential cure. Yet, even among patients that undergo tumor resection, recurrence rates are high and long-term survival is scarce. Various tumor-related factors have been identified as predictors of survival after potentially curative resection. These factors include tumor size, lymph node disease, tumor grade, vascular invasion, perineural invasion and surgical resection margin. This article will re-evaluate the importance of these factors based on recent publications on the topic, with potential implications for treatment and outcome in patients with pancreatic cancer. PMID:27605878

  4. A Pd/silica composite with highly uniform Pd nanoparticles on silica lamella via layered silicate

    NASA Astrophysics Data System (ADS)

    Hao, Jing; Cui, Zhi-Min; Cao, Chang-Yan; Song, Weiguo

    2016-08-01

    Pd nanoparticles was loaded on silica lamella via layered silicate through a simple ion-exchange and in situ reduction method. The obtained Pd/silica composite has Pd nanoparticles with highly uniform size dispersed well on the silica lamella. The Pd/silica composite is active and recoverable catalyst for the hydrogenation reaction and the reaction can be completed in a short time of 2 h at room temperature and 1 atm H2 pressure.

  5. Cellular membrane trafficking of mesoporous silica nanoparticles

    SciTech Connect

    Fang, I-Ju

    2012-01-01

    This dissertation mainly focuses on the investigation of the cellular membrane trafficking of mesoporous silica nanoparticles. We are interested in the study of endocytosis and exocytosis behaviors of mesoporous silica nanoparticles with desired surface functionality. The relationship between mesoporous silica nanoparticles and membrane trafficking of cells, either cancerous cells or normal cells was examined. Since mesoporous silica nanoparticles were applied in many drug delivery cases, the endocytotic efficiency of mesoporous silica nanoparticles needs to be investigated in more details in order to design the cellular drug delivery system in the controlled way. It is well known that cells can engulf some molecules outside of the cells through a receptor-ligand associated endocytosis. We are interested to determine if those biomolecules binding to cell surface receptors can be utilized on mesoporous silica nanoparticle materials to improve the uptake efficiency or govern the mechanism of endocytosis of mesoporous silica nanoparticles. Arginine-glycine-aspartate (RGD) is a small peptide recognized by cell integrin receptors and it was reported that avidin internalization was highly promoted by tumor lectin. Both RGD and avidin were linked to the surface of mesoporous silica nanoparticle materials to investigate the effect of receptor-associated biomolecule on cellular endocytosis efficiency. The effect of ligand types, ligand conformation and ligand density were discussed in Chapter 2 and 3. Furthermore, the exocytosis of mesoporous silica nanoparticles is very attractive for biological applications. The cellular protein sequestration study of mesoporous silica nanoparticles was examined for further information of the intracellular pathway of endocytosed mesoporous silica nanoparticle materials. The surface functionality of mesoporous silica nanoparticle materials demonstrated selectivity among the materials and cancer and normal cell lines. We aimed to determine

  6. Self-Reevaluation as a Critical Component in Sustained Viral Load Change for HIV+ Adults with Alcohol Problems

    PubMed Central

    Longmire-Avital, Buffie; Golub, Sarit A.

    2010-01-01

    Self-reevaluation is one of the ten processes of change in the transtheoretical model and involves cognitive reappraisal of how behavior change is part of one’s identity. Although self-reevaluation is a critical motivator for individuals in the contemplation stage of change, few studies have examined its impact on disease progression associated with sustained behavior change. This study investigated the contribution of self-reevaluation on sustained viral load improvement among 143 participants in a randomized controlled trial testing an eight-session intervention (Project Positive Living through Understanding and Support) designed to improve treatment adherence among HIV+ adults with alcohol problems. Participants’ self-reevaluation scores at 3 months emerged as significant and independent predictors of sustained improvement in viral load at 6 months, over and above self-reported HAART dose adherence (p<0.05). Results underscore the role of self-reevaluation as a critical factor in behavioral interventions and highlight its role in sustained change necessary to slow disease progression. PMID:20668976

  7. HEALTH EFFECTS OF INHALED CRYSTALLINE AND AMORPHOUS SILICA

    EPA Science Inventory

    Recently, public concern regarding nonoccupational or ambient silica exposure, mainly to crystalline silica, has emerged making it important to evaluate background and ambient concentrations. Ambient emissions of silica rarely are estimated or measured in air pollution studies of...

  8. Moisture Transport in Silica Gel Particle Beds: I. Theoretical Study

    SciTech Connect

    Pesaran, A. A.; Mills, A. F.

    1986-08-01

    Diffusion mechanisms of moisture within silica gel particles are investigated. It is found that for microporous silica gel surface diffusion is the dominant mechanism of moisture transport, while for macroporous silica gel both Knudsen and surface diffusion are important.

  9. Sulphur-doped silica fibres

    SciTech Connect

    Gerasimova, V I; Rybaltovskii, A O; Chernov, P V; Mashinsky, V M; Sazhin, O D; Medvedkov, O I; Rybaltovsky, A A; Khrapko, R R

    2003-01-31

    An optical fibre with low optical losses is manufactured from a sulphur-doped quartz glass. Optical absorption spectra are measured for various parts of the fibre core. Most of the bands of these spectra are assigned to oxygen-deficient centres and colour centres containing sulphur atoms. The photosensitivity of glasses exposed to laser radiation at wavelengths of 193 and 244 nm is investigated to estimate the possibility of their application for producing photorefracting devices. A Bragg grating of the refractive index with {Delta}n = 7.8 x 10{sup -4} is written in a sulphur-doped silica fibre. (fibre optics)

  10. Nanoscale control of silica particle formation via silk-silica fusion proteins for bone regeneration.

    PubMed

    Mieszawska, Aneta J; Nadkarni, Lauren D; Perry, Carole C; Kaplan, David L

    2010-10-26

    The biomimetic design of silk/silica fusion proteins was carried out, combining the self assembling domains of spider dragline silk (Nephila clavipes) and silaffin derived R5 peptide of Cylindrotheca fusiformis that is responsible for silica mineralization. Genetic engineering was used to generate the protein-based biomaterials incorporating the physical properties of both components. With genetic control over the nanodomain sizes and chemistry, as well as modification of synthetic conditions for silica formation, controlled mineralized silk films with different silica morphologies and distributions were successfully generated; generating 3D porous networks, clustered silica nanoparticles (SNPs), or single SNPs. Silk serves as the organic scaffolding to control the material stability and multiprocessing makes silk/silica biomaterials suitable for different tissue regenerative applications. The influence of these new silk-silica composite systems on osteogenesis was evaluated with human mesenchymal stem cells (hMSCs) subjected to osteogenic differentiation. hMSCs adhered, proliferated, and differentiated towards osteogenic lineages on the silk/silica films. The presence of the silica in the silk films influenced osteogenic gene expression, with the upregulation of alkaline phosphatase (ALP), bone sialoprotein (BSP), and collagen type 1 (Col 1) markers. Evidence for early bone formation as calcium deposits was observed on silk films with silica. These results indicate the potential utility of these new silk/silica systems towards bone regeneration. PMID:20976116

  11. DNA Binding to the Silica Surface.

    PubMed

    Shi, Bobo; Shin, Yun Kyung; Hassanali, Ali A; Singer, Sherwin J

    2015-08-27

    We investigate the DNA-silica binding mechanism using molecular dynamics simulations. This system is of technological importance, and also of interest to explore how negatively charged DNA can bind to a silica surface, which is also negatively charged at pH values above its isoelectric point near pH 3. We find that the two major binding mechanisms are attractive interactions between DNA phosphate and surface silanol groups and hydrophobic bonding between DNA base and silica hydrophobic region. Umbrella sampling and the weighted histogram analysis method (WHAM) are used to calculate the free energy surface for detachment of DNA from a binding configuration to a location far from the silica surface. Several factors explain why single-stranded DNA (ssDNA) has been observed to be more strongly attracted to silica than double-stranded (dsDNA): (1) ssDNA is more flexible and therefore able to maximize the number of binding interactions. (2) ssDNA has free unpaired bases to form hydrophobic attachment to silica while dsDNA has to break hydrogen bonds with base partners to get free bases. (3) The linear charge density of dsDNA is twice that of ssDNA. We devise a procedure to approximate the atomic forces between biomolecules and amorphous silica to enable large-scale biomolecule-silica simulations as reported here. PMID:25966319

  12. Reusable silica surface-insulation material

    NASA Technical Reports Server (NTRS)

    Goldstein, H. E.; Smith, M.; Leiser, D.

    1973-01-01

    Material was specifically developed for manufacture of insulating tiles, but it can be molded into other shapes as required. Basic raw materials are high-purity silica fiber, fumed-silica powder, and reagent-grade starch. Only purest materials are used, and care must be taken to avoid contamination during processing.

  13. Biomimetic silica encapsultation of living cells

    NASA Astrophysics Data System (ADS)

    Jaroch, David Benjamin

    Living cells perform complex chemical processes on size and time scales that artificial systems cannot match. Cells respond dynamically to their environment, acting as biological sensors, factories, and drug delivery devices. To facilitate the use of living systems in engineered constructs, we have developed several new approaches to create stable protective microenvironments by forming bioinspired cell-membrane-specific silica-based encapsulants. These include vapor phase deposition of silica gels, use of endogenous membrane proteins and polysaccharides as a site for silica nucleation and polycondensation in a saturated environment, and protein templated ordered silica shell formation. We demonstrate silica layer formation at the surface of pluripotent stem-like cells, bacterial biofilms, and primary murine and human pancreatic islets. Materials are characterized by AFM, SEM and EDS. Viability assays confirm cell survival, and metabolite flux measurements demonstrate normal function and no major diffusion limitations. Real time PCR mRNA analysis indicates encapsulated islets express normal levels of genetic markers for β-cells and insulin production. The silica glass encapsulant produces a secondary bone like calcium phosphate mineral layer upon exposure to media. Such bioactive materials can improve device integration with surrounding tissue upon implantation. Given the favorable insulin response, bioactivity, and long-term viability observed in silica-coated islets, we are currently testing the encapsulant's ability to prevent immune system recognition of foreign transplants for the treatment of diabetes. Such hybrid silica-cellular constructs have a wide range of industrial, environmental, and medical applications.

  14. Chemically-bound xenon in fibrous silica.

    PubMed

    Kalinowski, Jaroslaw; Räsänen, Markku; Gerber, R Benny

    2014-06-21

    High-level quantum chemical calculations reported here predict the existence and remarkable stability, of chemically-bound xenon atoms in fibrous silica. The results may support the suggestion of Sanloup and coworkers that chemically-bound xenon and silica account for the problem of "missing xenon" (by a factor of 20!) from the atmospheres of Earth and Mars. So far, the host silica was assumed to be quartz, which is in contradiction with theory. The xenon-fibrous silica molecule is computed to be stable well beyond room temperature. The calculated Raman spectra of the species agree well with the main features of the experiments by Sanloup et al. The results predict computationally the existence of a new family of noble-gas containing materials. The fibrous silica species are finite molecules, their laboratory preparation should be feasible, and potential applications are possible. PMID:24807740

  15. Sample Desorption/Onization From Mesoporous Silica

    DOEpatents

    Iyer, Srinivas; Dattelbaum, Andrew M.

    2005-10-25

    Mesoporous silica is shown to be a sample holder for laser desorption/ionization of mass spectrometry. Supported mesoporous silica was prepared by coating an ethanolic silicate solution having a removable surfactant onto a substrate to produce a self-assembled, ordered, nanocomposite silica thin film. The surfactant was chosen to provide a desired pore size between about 1 nanometer diameter and 50 nanometers diameter. Removal of the surfactant resulted in a mesoporous silica thin film on the substrate. Samples having a molecular weight below 1000, such as C.sub.60 and tryptophan, were adsorbed onto and into the mesoporous silica thin film sample holder and analyzed using laser desorption/ionization mass spectrometry.

  16. High purity silica reflecting heat shield development

    NASA Technical Reports Server (NTRS)

    Congdon, W.

    1974-01-01

    A reflecting heat shield composed of fused silica in which the scattering results from the refractive index mismatch between silica particles and the voids introduced during the fabrication process is developed. Major considerations and conclusions of the development are: the best material to use is Type A, which is capable of ultra-high-purity and which does not show the 0.243 micrometer absorption band; the reflection efficiency of fused silica is decreased at higher temperatures due to the bathochromic shift of the ultraviolet cut-off; for a given silica material, over the wavelength region and particle sizes tested, the monodisperse particle size configurations produce higher reflectances than continuous particle size configurations; and the smaller monodisperse particle size configurations give higher reflectance than the larger ones. A reflecting silica configuration that is an efficient reflector of shock layer radiation at high ablation temperatures is achieved by tailoring the matrix for optimum scattering and using an ultra-high-purity material.

  17. Fire effects on silica fractionation

    NASA Astrophysics Data System (ADS)

    Unzué-Belmonte, Dácil; Schaller, Jörg; Vandevenne, Floor; Barao, Lúcia; Struyf, Eric; Meire, Patrick

    2015-04-01

    Fire events are expected to increase due to climate change, both in number and intensity Effects range from changes in soil biogeochemistry up to the whole ecosystem functioning and morphology. While N, P and C cycling have received quite some attention, little attention was paid to fire effects on the biogeochemical Si cycle and the consequences after a fire event. The Si cycle is a globally important biogeochemical cycle, with strong connections to other biogeochemical cycles, including C. Dissolved silica is taken up by plants to form protective structures called phytoliths, which become a part of the soil and contribute strongly to soil Si cycling upon litter burial. Different silica fractions are found in soils, with phytoliths among the most easily soluble, especially compared to silicate minerals. A whole set of secondary non-biogenic fractions exist, that also have a high reactivity (adsorbed Si, reactive secondary minerals…). Biogenic and other pedogenic secondary Si stocks form an important filter between weathering of mineral silicates and eventual transport of dissolved Si to rivers and the coastal zone. We used a new method to analyze the different reactive fractions of silica in the litter layer of 3 ecosystems after different fire treatments. Using a continuous extraction of Si and Al in 0.5M NaOH at 85°C, biogenic and non-biogenic alkaline reactive Si fractions can be separated based on their Si/Al ratios and their reactivity. We analyzed the silica fractionation after two burning treatments (no heating, 350°C and 550°C) from three types of litter (spruce forest, beech forest and Sphagnum peat). Reactive Si from litter of spruce and beech forest was purely biogenic, based on the observed Si/Al ratio. Beech litter (~2.2 % BSi) had two different biogenic silica pools, one reactive and one more refractory. Spruce litter (~1.5% BSi) showed only one fraction of biogenic Si. There was negligible biogenic Si present in the peat samples (<0.1%). While

  18. Fluid diffusion in porous silica

    NASA Astrophysics Data System (ADS)

    McCann, Lowell I.

    Fluid motion in porous media has received a great deal of theoretical and experimental attention due to its importance in systems as diverse as ground water aquifers, catalytic processes, and size separation schemes. Often, the motion of interest is the random thermal motion of molecules in a fluid undergoing no net flow. This diffusive motion is particularly important when the size of the pores is nearly the same as the size of the molecules. In this study, fluid diffusion is measured in several varieties of porous silica whose pore structure is determined by the process by which it is made. The samples in this study have porosities (φ, the ratio of the pore volume to the total sample volume) that vary from 0.3 to 0.75 and average pore radii that range from approximately 15 to 120 A. Determining the effect of the pore structure on the diffusion of a liquid in a porous material is complicated by the chemical interactions between the diffusing molecules and the pore surface. In this study, ions in a hydrophilic fluid are used to block the adsorption of the diffusing dye molecules to the hydroxyl groups covering the silica surface. This technique is unlike typical surface treatments of silica in that it does not permanently alter the pore geometry. In this work, fluid diffusion is measured with a transient holographic grating technique where interfering laser beams create a periodic refractive index modulation in the fluid. The diffraction of a third laser off this grating is monitored to determine how quickly the grating relaxes, thereby determining the diffusion coefficient of the molecules in the fluid. Varying the grating periodicity controls the length scale of the diffusion measurement from 1.2 to 100 μm which is much larger than the average pore sizes of the samples. Therefore, over these large scales, we measure 'normal' diffusion, where the mean squared displacement of a diffusing particle varies linearly with time. In one particular type of porous silica

  19. A reevaluation of the literature regarding the health assessment of diesel engine exhaust.

    PubMed

    Bunn, William B; Hesterberg, Thomas W; Valberg, Peter A; Slavin, Thomas J; Hart, Georgia; Lapin, Charles A

    2004-12-15

    While the International Agency for Research on Cancer (IARC) classified diesel exhaust (DE) as a"probable"carcinogen in 1989 based primarily on"sufficient"animal data, other investigators have since concluded that the lung tumors found in the rat studies were a result of particle overloading. Subsequent health risk assessments of DE have not used the rat cancer data. The U.S. Environmental Protection Agency (EPA), in developing its 2002 Health Assessment Document (HAD) for DE, primarily considered the epidemiology studies of railroad workers and truck drivers to develop health risk assessments of DE. However, both sets of epidemiology studies have serious weaknesses that make them unsuitable for cancer risk assessment. Major shortcomings were the lack of contemporaneous measurements of exposures to DE, difficulties with exposure history reconstruction, and adequately accounting for other exposures such as gasoline exhaust and cigarette smoke. To compound these problems, there was not, and there is still not, a specific exposure marker for DE. Interestingly, in the underground mining industry, where diesel exposures are much higher than observed in railroad workers and truck drivers, there was no increase in lung cancer. These problems and concerns led the U.S. EPA to conclude that while DE was a"likely"carcinogen, a unit risk value or range of risk cannot be calculated from existing data and that the risk could be zero. In addition, the DE emissions have changed and continue to change with the implementation of new emission control technologies. The HAD recognized this fact and noted that further studies are needed to assess new diesel engine emissions. Recent chemical characterization studies on low-emitting diesel engines with catalyzed particulate filters have shown emissions rates for several chemicals of concern that are even lower than comparable compressed natural gas (CNG)-fueled engines. With lower emissions, better fire safety, and improved cost

  20. Modified Mesoporous Silica for Efficient Siloxane Capture.

    PubMed

    Jafari, Tahereh; Jiang, Ting; Zhong, Wei; Khakpash, Nasser; Deljoo, Bahareh; Aindow, Mark; Singh, Prabhakar; Suib, Steven L

    2016-03-15

    In this study, octamethylcyclotetrasiloxane (D4) was removed by using a novel modified solid adsorbent of mesoporous silica. The adsorbent was synthesized using inverse micelles with some modifications in the synthesis process (temperature of gelation) and in the post treatment conditions (calcination temperature and heating rate) with a concomitant improvement of D4 uptake. This is the first report on regulating the textural properties of the mesoporous silica material UCT-14 to develop an active silica adsorbent. These adjustments resulted in an increase of the silica surface area from 391 to 798 m(2)·g(-1), which leads to a high capacity (686 mg·g(-1)) of D4-capture for the silica synthesized at 80 °C, calcined at 450 °C with the heating rate of 100 °C·min(-1) (Si-Syn80). This adsorbent showed comparable adsorption performance with the widely used commercial silica gel under dry and humid condition. Recyclability tests on the commercial silica gel and mesoporous silica synthesized at 120 °C and calcined at 450 °C with a heating rate of 100 °C·min(-1) (called Si-Syn120 or Si-450 or Si-100 °C·min(-1)) indicated that the Si-Syn120 (capacity drop 10%) is more efficient than silica gel (capacity drop 15%) after three cycles. Although, the presence of moisture (25%) in the nitrogen gas stream led to capacity reduction in both Si-Syn120 and commercial silica gel, the modified UCT-14 shows slightly better resistance to humid condition. PMID:26890152

  1. THE 2005 WORLD HEALTH ORGANIZATION RE-EVALUATION OF HUMAN AND MAMMALIAN TOXIC EQUIVALENCY FACTORS FOR DIOXINS AND DIOXIN-LIKE COMPOUNDS

    EPA Science Inventory

    In June 2005 a WHO-IPCS expert meeting was held in Geneva during which the toxic equivalency factors (TEFs) for dioxin like compounds, including some polychlorinated biphenyls (PCBs), were re-evaluated. For this re-evaluation process the refined TEF database recently published by...

  2. Encapsulation of silica nanoparticles by redox-initiated graft polymerization from the surface of silica nanoparticles.

    PubMed

    Wang, Huijun; Peng, Mao; Zheng, Jun; Li, Peng

    2008-10-01

    This study describes a facile and versatile method for preparing polymer-encapsulated silica particles by 'grafting from' polymerization initiated by a redox system comprising ceric ion (Ce(4+)) as an oxidant and an organic reductant immobilized on the surface of silica nanoparticles. The silica nanoparticles were firstly modified by 3-aminopropyltriethoxysilane, then reacted with poly(ethylene glycol) acrylate through the Michael addition reaction, so that hydroxyl-terminated poly(ethylene glycol) (PEG) were covalently attached onto the nanoparticle surface and worked as the reductant. Poly(methyl methacrylate) (PMMA), a common hydrophobic polymer, and poly(N-isopropylacrylamide) (PNIPAAm), a thermosensitive polymer, were successfully grafted onto the surface of silica nanoparticles by 'grafting from' polymerization initiated by the redox reaction of Ce(4+) with PEG on the silica surface in acid aqueous solutions. The polymer-encapsulated silica nanoparticles (referred to as silica@PMMA and silica@PNIPAAm, respectively) were characterized by infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy. On the contrary, graft polymerization did not occur on bare silica nanoparticles. In addition, during polymerization, sediments were observed for PMMA and for PNIPAAm at a polymerization temperature above its low critical solution temperature (LCST). But the silica@PNIPAAm particles obtained at a polymerization temperature below the LCST can suspend stably in water throughout the polymerization process. PMID:18684468

  3. Antenatal Supervision—A Review of Obstetrical Care with Suggestions for Reevaluation

    PubMed Central

    Fox, Leon Parrish

    1964-01-01

    Studies by California Maternal Mortality Study Committees over a period of six years have revealed many avoidable inadequacies in the care of pregnant patients. Other reviews have shown a high incidence of non-fatal complications arising early in pregnancy when care is often inadequate. Since antenatal care is justly credited with the vast improvement of the incidence of maternal mortality, maternal morbidity and perinatal salvage, it is time for a reevaluation and upgrading of present-day practices. Responsibility is shared by the medical and auxiliary professions and the community. The public as well as those who care for the expectant mother must have improved educational exposure to achieve better results. PMID:14199085

  4. Re-Evaluating Sexual Violence Prevention Through Bystander Education: A Latent Growth Curve Approach.

    PubMed

    Shaw, Jessica; Janulis, Patrick

    2016-10-01

    Recently, there has been a call for more advanced analytic techniques in violence against women research, particularly in community interventions that use longitudinal designs. The current study re-evaluates experimental evaluation data from a sexual violence bystander intervention program. Using an exploratory latent growth curve approach, we were able to model the longitudinal growth trajectories of individual participants over the course of the entire study. Although the results largely confirm the original evaluation findings, the latent growth curve approach better fits the demands of "messy" data (e.g., missing data, varying number of time points per participant, and unequal time spacing within and between participants) that are frequently obtained during a community-based intervention. The benefits of modern statistical techniques to practitioners and researchers in the field of sexual violence prevention, and violence against women more generally, are further discussed. PMID:25888503

  5. Reply to "Comment on `Reevaluation of the parton distribution of strange quarks in the nucleon'"

    NASA Astrophysics Data System (ADS)

    Aschenauer, E. C.; Jackson, H. E.; Joosten, S.; Rith, K.; Schnell, G.; van Hulse, C.; HERMES Collaboration

    2015-11-01

    A Comment on the recently published reevaluation of the polarization-averaged parton distribution of strange quarks in the nucleon using final data on the multiplicities of charged kaons in semi-inclusive deep-inelastic scattering (DIS) is reviewed. Important features of the comparison of one-dimensional projections of the multidimensional HERMES data are pointed out. A test of the leading-order extraction of xB S (xB) using the difference between charged-kaon multiplicities is repeated. The results are consistent with leading-order predictions within the uncertainties in the input data, and do not invalidate the earlier extraction of xB S (xB) .

  6. Re-evaluation of the 1962 Mark VI-B dynamic tests regarding reactivity coefficients

    SciTech Connect

    Burnett, T.

    1991-06-01

    The 1962 Mark VI-B rod tests have been re-evaluated. A significantly lower (more negative) coolant coefficient is now ascribed to that test, {minus}1 pcm/Deg-C vs the previously reported +2 pcm/Deg-C. The change from the previous value is because of revisions to delayed neutron constants and accounting for spatial effects. The new value is in reasonable agreement with the currently calculated value of {minus}2 pcm/Deg-C, considering measurement and calculational uncertainties. Therefore, the authors conclude that the current analytic models for physics and transient analysis methodology (GLASS, GRIMHX & TRIMHX, AND MARY) are fully consistent with 1962 test observations, and that there is no basis for assigning a calculational bias or increasing uncertainty allowances.

  7. Reevaluation of an individual's radiation exposure at NTS in 1963-64. [FRAN reactor

    SciTech Connect

    Myers, D.S.

    1983-02-25

    The FRAN prompt burst reactor began operation at NTS on November 1, 1962 and continued in use until April 1965. From January 2, 1963 to August 12, 1964, an individual periodically performed maintenance and troubleshooting functions on various components of the FRAN reactor system. In June, 1980, the individual requested a review of the radiation dose that he received from his involvement with the FRAN reactor. An evaluation of the individual's radiation dose associated with the FRAN reactor operation was performed. This report details the reevaluation of the individual's estimated radiation dose from the FRAN reactor assembly, as derived from computer calculations, GODIVA-IV measurements, personnel dosimetry results, and a reconstruction of work scenarios.

  8. Reevaluating the tectonic uplift of western Mount Carmel, Israel, since the middle Pleistocene

    NASA Astrophysics Data System (ADS)

    Zviely, Dov; Galili, Ehud; Ronen, Avraham; Salamon, Amos; Ben-Avraham, Zvi

    2009-03-01

    Reevaluation of geological and archaeological evidence from western Mount Carmel constrains its maximal tectonic uplift since the Middle Pleistocene. Tabun Cave, presently 45 m above sea level (asl), revealed human occupation from about 600 ka to 90 ka before present. The 25 m thick archaeological strata at Tabun are composed of laminated fine sand, silt and clays. Moreover, no marine deposits were found in Tabun or nearby caves. Since sea level in the last 600 ka reached a maximal of 5 to 10 m asl, Tabun Cave could not have been uplifted since then by more than 35 to 40 m, that is a maximal average rate of 58 to 67 mm/ka.

  9. A reevaluation of Stogryn's apparent temperature theory over the sea surface

    NASA Technical Reports Server (NTRS)

    Fung, A. K.; Eom, H. J.

    1984-01-01

    The emission theory for the sea surface by Stogryn has been reevaluated. Results agree with Stogryn's paper except for small nadir angles where the apparent temperature versus wind speed behavior is in reverse of what was reported by Stogryn. By plotting the change in contributions by the sea surface emission and sky temperature scattered toward the radiometer as a function of nadir angle at two different wind speeds, it is found that the sky temperature effect is dominating at small nadir angles, while the change in surface emission becomes increasingly more important at larger nadir angles. It is also found that at nadir higher emission is associated with the polarization where E(arrow) field is aligned along the upwind direction than the one along the crosswind direction.

  10. Reevaluation of the macroseismic effects of the 23 January 1838 Vrancea earthquake

    NASA Astrophysics Data System (ADS)

    Rogozea, M.; Marmureanu, Gh.; Radulian, M.

    2012-04-01

    The aim of this paper is to analyze the great event that occurred on 23 January 1838 (magnitude 7.5 in the Romanian catalogue). Valuable information has been collected from original or compiled historical sources, such as chronicles and manuscripts on that time, and related books and reports. The historical data are critically analyzed and, on the basis of our investigation, we showed the degree of significance of the earthquake parameters, as resulted from the effect distribution. The pattern of the intensity data points as reevaluated for this historical earthquake is compared with the pattern of instrumentally recorded major earthquake of 4 March 1977, the two events assumed to be similar as hypocenter location, source parameters and rupture propagation. We make also a comparative investigation for the attenuation relationship in case of Vrancea earthquakes, using historical data vs. instrumental data. Implications for the seismic hazard assessment are finally discussed.

  11. Metal-silica sol-gel materials

    NASA Technical Reports Server (NTRS)

    Stiegman, Albert E. (Inventor)

    2002-01-01

    The present invention relates to a single phase metal-silica sol-gel glass formed by the co-condensation of a transition metal with silicon atoms where the metal atoms are uniformly distributed within the sol-gel glass as individual metal centers. Any transition metal may be used in the sol-gel glasses. The present invention also relates to sensor materials where the sensor material is formed using the single phase metal-silica sol-gel glasses. The sensor materials may be in the form of a thin film or may be attached to an optical fiber. The present invention also relates to a method of sensing chemicals using the chemical sensors by monitoring the chromatic change of the metal-silica sol-gel glass when the chemical binds to the sensor. The present invention also relates to oxidation catalysts where a metal-silica sol-gel glass catalyzes the reaction. The present invention also relates to a method of performing oxidation reactions using the metal-silica sol-gel glasses. The present invention also relates to organopolymer metal-silica sol-gel composites where the pores of the metal-silica sol-gel glasses are filled with an organic polymer polymerized by the sol-gel glass.

  12. Light-Induced Surface Patterning of Silica.

    PubMed

    Kang, Hong Suk; Lee, Seungwoo; Choi, Jaeho; Lee, Hongkyung; Park, Jung-Ki; Kim, Hee-Tak

    2015-10-27

    Manipulating the size and shape of silica precursor patterns using simple far-field light irradiation and transforming such reconfigured structures into inorganic silica patterns by pyrolytic conversion are demonstrated. The key concept of our work is the use of an azobenzene incorporated silica precursor (herein, we refer to this material as azo-silane composite) as ink in a micromolding process. The moving direction of azo-silane composite is parallel to light polarization direction; in addition, the amount of azo-silane composite movement can be precisely determined by controlling light irradiation time. By exploiting this peculiar phenomenon, azo-silane composite patterns produced using the micromolding technique are arbitrarily manipulated to obtain various structural features including high-resolution size or sophisticated shape. The photoreconfigured patterns formed with azo-silane composites are then converted into pure silica patterns through pyrolytic conversion. The pyrolytic converted silica patterns are uniformly formed over a large area, ensuring crack-free formation and providing high structural fidelity. Therefore, this optical manipulation technique, in conjunction with the pyrolytic conversion process, opens a promising route to the design of silica patterns with finely tuned structural features in terms of size and shape. This platform for designing silica structures has significant value in various nanotechnology fields including micro/nanofluidic channel for lab-on-a-chip devices, transparent superhydrophobic surfaces, and optoelectronic devices. PMID:26389813

  13. Crystalline silica: risks and policy.

    PubMed Central

    Hardy, T S; Weill, H

    1995-01-01

    Since the International Agency for Research on Cancer labeled crystalline silica a probable carcinogen in 1988, government regulations have required sand and other products to contain warning labels and researchers have attempted to quantitatively assess low-exposure risks. The uncertainties are unlikely to diminish any time soon, and little value exists in calculating such risks, as low exposures to this ubiquitous mineral are commonplace in both urban and rural areas due to many uncontrollable activities. What is certain is that regulatory resources targeted at continuing high-level occupational exposures would be much more likely to have beneficial public health consequences than continued attempts to assess low-exposure risks quantitatively. Images p152-a PMID:7737062

  14. 41 CFR 301-70.602 - How often must we reevaluate the payment of transportation and subsistence expenses to a...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 41 Public Contracts and Property Management 4 2012-07-01 2012-07-01 false How often must we reevaluate the payment of transportation and subsistence expenses to a threatened law enforcement/investigative employee? 301-70.602 Section 301-70.602 Public Contracts and Property Management Federal Travel Regulation System TEMPORARY DUTY (TDY)...

  15. [Post-marketing reevaluation for potential quality risk and quality control in clinical application of traditional Chinese medicines].

    PubMed

    Li, Hong-jiao; He, Li-yun; Liu, Bao-yan

    2015-06-01

    The effective quality control in clinical practices is an effective guarantee for the authenticity and scientificity of the findings. The post-marketing reevaluation for traditional Chinese medicines (TCM) focuses on the efficacy, adverse reaction, combined medication and effective dose of drugs in the market by expanded clinical trials, and requires a larger sample size and a wider range of patients. Therefore, this increases the difficulty of quality control in clinical practices. With the experience in quality control in clinical practices for the post-marketing reevaluation for Kangbingdu oral for cold, researchers in this study reviewed the study purpose, project, scheme design and clinical practice process from an overall point of view, analyzed the study characteristics of the post-marketing reevaluation for TCMs and the quality control risks, designed the quality control contents with quality impacting factors, defined key review contents and summarized the precautions in clinical practices, with the aim to improve the efficiency of quality control of clinical practices. This study can provide reference to clinical units and quality control-related personnel in the post-marketing reevaluation for TCMs. PMID:26591543

  16. Re-evaluation of broiler carcass scalding protocols for impact on the recovery of Campylobacter from breast skin after defeathering

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This research re-evaluated the impact of scalding protocols on the recovery of Campylobacter from breast skin following defeathering after preliminary processing trials detected Campylobacter from breast skin for 4/8 carcasses that had vents plugged and sutured prior to scalding. Published research...

  17. Re-evaluation of Non-regulatory Asbestos Group Minerals for Regulatory Agencies

    NASA Astrophysics Data System (ADS)

    Dogan, M.; Dogan, A.

    2013-05-01

    There are established rules and regulations for some asbestos group minerals - amphibole group minerals of actinolite, amosite, anthophyllite, crocidolite, tremolite; and serpentine group minerals of chrysotile- called "regulatory". There are also "non-regulatory" naturally occurring asbestos (NOA) group minerals as constituent of rocks and soil, including richterite, winchite, fluoro-edenite, balangeroite, carlosturanite, gageite, arfvedsonite, and magnesio-arfvedsonite. Strong evidences for carcinogenicity of these NOA minerals in later cohorts of cancer patients demonstrated the risks associated with these minerals. In addition, although the chrysotile asbestos regulated by some organizations such as WHO, World Trade Organization, United Nations, US EPA, International Labour Organization, and EU Countries; however, controversies still continue surrounding the use of chrysotile. Determinations of polymineralic fibrous veins, mixed particles, amphibole cleavage fragments, and genetic predisposition are also important issues (i.e. Dogan et al., 2006).Therefore, accurate characterizations of chemical composition, morphology, structure, and defects are necessary in order to find out mechanism(s) of carcinogenicity of all asbestos group minerals. Calculation methods of chemical composition are still under debate because of assumption of no vacancies at any sites and intergrowth of minerals. Substitution(s) may cause deviations from the ideal chemical formula and wide variations in chemical compositions. Detail morphological and chemical quantification of individual asbestos group minerals in micro- and nano-scale may help to evaluate its true carcinogenetic mechanism(s), and consequently prevention and possibly treatment of related diseases. we propose that nonregulatory asbestos minerals and the chrysotile should be re-evaluated. The amount of fibers inhaled, in terms of weight percent and number, need also be re-evaluated by mineralogists. Finally, Regulatory

  18. Inverse melting in stressed fused silica

    NASA Astrophysics Data System (ADS)

    Bouchut, Philippe

    2012-12-01

    The emissive properties of proton implanted fused silica surfaces have been studied by laser beam annealing. When submitted to a high thermal step from a focused CO2 laser, an intense near infra-red thermoluminescence peak rises at a heating rate threshold. The in plane tensile stress relaxes and silica melts. We show that in the irreversible inverse melting of stressed fused silica, the protons exo-diffuse through internal modes coupling. The heat and mass transfer is one entropy flux whose dynamics are regulated by the mass transport. Inverse melting is the thermodynamic process that initiates the glass transition when heating.

  19. Fluorine-Based DRIE of Fused Silica

    NASA Technical Reports Server (NTRS)

    Yee, Karl; Shcheglov, Kirill; Li, Jian; Choi, Daniel

    2007-01-01

    A process of deep reactive-ion etching (DRIE) using a fluorine-based gas mixture enhanced by induction-coupled plasma (ICP) has been demonstrated to be effective in forming high-aspect-ratio three-dimensional patterns in fused silica. The patterns are defined in part by an etch mask in the form of a thick, high-quality aluminum film. The process was developed to satisfy a need to fabricate high-aspect-ratio fused-silica resonators for vibratory microgyroscopes, and could be used to satisfy similar requirements for fabricating other fused-silica components.

  20. Nonporous Silica Nanoparticles for Nanomedicine Application

    PubMed Central

    Tang, Li; Cheng, Jianjun

    2013-01-01

    Summary Nanomedicine, the use of nanotechnology for biomedical applications, has potential to change the landscape of the diagnosis and therapy of many diseases. In the past several decades, the advancement in nanotechnology and material science has resulted in a large number of organic and inorganic nanomedicine platforms. Silica nanoparticles (NPs), which exhibit many unique properties, offer a promising drug delivery platform to realize the potential of nanomedicine. Mesoporous silica NPs have been extensively reviewed previously. Here we review the current state of the development and application of nonporous silica NPs for drug delivery and molecular imaging. PMID:23997809

  1. Fused Silica and Other Transparent Window Materials

    NASA Technical Reports Server (NTRS)

    Salem, Jon

    2016-01-01

    Several transparent ceramics, such as spinel and AlONs are now being produced in sufficient large areas to be used in space craft window applications. The work horse transparent material for space missions from Apollo to the International Space Station has been fused silica due in part to its low coefficient of expansion and optical quality. Despite its successful use, fused silica exhibits anomalies in its crack growth behavior, depending on environmental preconditioning and surface damage. This presentation will compare recent optical ceramics to fused silica and discuss sources of variation in slow crack growth behavior.

  2. Silica burp in the Eocene ocean

    NASA Astrophysics Data System (ADS)

    McGowran, Brian

    1989-09-01

    The Eocene was a time of greatly increased silica accumulation in the ocean, and the peak was in the early middle Eocene at about 50 Ma. The responsible geohistorical configuration included the following elements: extensive volcanism about 4 m.y. earlier, as part of the Chron 24 plate reorganization; early Eocene warming, with deep weathering to high latitudes and accumulation of the released silica in a sluggish ocean; and sharp cooling in the earliest middle Eocene, stimulating oceanic upwelling and biosilicification. It is possible, on the evidence of carbon and oxygen isotopic patterns, that the trigger for the exhalation of silica was a reverse greenhouse effect.

  3. Preparing mesoporous carbon and silica with rosin-silica composite gel.

    PubMed

    Liu, Haidi; Du, Shangfeng; Chen, Yunfa

    2009-02-01

    Mesoporous carbon and mesoporous silica were prepared respectively with a same rosin-silica nanocomposite gel which was synthesized by cogelating tetra-ethyl-oxy-silane (silica source) and rosin (carbon source). Carbonizing the gel in nitrogen and then etching away silica with alkaline solution, mesoporous carbon with specific surface area larger than 800 m2/g was obtained. If calcining the gel at high temperature in air for given time, porous silica with surface area higher than 700 m2/g was done. BET measurement was employed to investigate the pore distribution and surface area of the samples. Most of the pores in both the porous carbon and porous silica were mesoscale, which makes the materials potential in enzyme supports for bio-catalyzed reaction or adsorbents for contaminants with large molecular size. PMID:19441395

  4. Self-Assembled Silica Nanostructures: Simultaneous Discrimination of Handedness, Pitch and Diameter of Helical Silica Nanotubes.

    PubMed

    Oh, C Y; Kim, D Y; Jin, S M; Kim, T K; Kim, J P; Jeong, E D; Hyun, M H; Sim, E K; Lee, Y C; Jin, J S

    2016-02-01

    The left- and right-handed helical silica nanostructures were obtained with the aid of organic templates, the formation of the nanostructures might follow a co-operation self-assembly mechanism. The chirality of the organogel self-assemblies was successfully transcribed in to the silica. The helical pitch and pore size of the silica nanotubes sensitively depended on the optical purity of the neutral gelator in the reaction mixtures. PMID:27433714

  5. Fungus-mediated biotransformation of amorphous silica in rice husk to nanocrystalline silica.

    PubMed

    Bansal, Vipul; Ahmad, Absar; Sastry, Murali

    2006-11-01

    Rice husk is a cheap agro-based waste material, which harbors a substantial amount of silica in the form of amorphous hydrated silica grains. However, there have been no attempts at harnessing the enormous amount of amorphous silica present in rice husk and its room-temperature biotransformation into crystalline silica nanoparticles. In this study, we address this issue and describe how naturally deposited amorphous biosilica in rice husk can be bioleached and simultaneously biotransformed into high value crystalline silica nanoparticles. We show here that the fungus Fusarium oxysporum rapidly biotransforms the naturally occurring amorphous plant biosilica into crystalline silica and leach out silica extracellularly at room temperature in the form of 2-6 nm quasi-spherical, highly crystalline silica nanoparticles capped by stabilizing proteins; that the nanoparticles are released into solution is an advantage of this process with significant application and commercial potential. Calcination of the silica nanoparticles leads to loss of occluded protein and to an apparently porous structure often of cubic morphology. The room-temperature synthesis of oxide nanomaterials using microorganisms starting from potential cheap agro-industrial waste materials is an exciting possibility and could lead to an energy-conserving and economically viable green approach toward the large-scale synthesis of oxide nanomaterials. PMID:17061888

  6. Procedure to prepare transparent silica gels

    NASA Technical Reports Server (NTRS)

    Barber, Patrick G. (Inventor); Simpson, Norman R. (Inventor)

    1987-01-01

    This invention relates to the production of silica gels and in particular to a process for the preparation of silica gels which can be used as a crystal growth medium that simulates the convectionless environment of space to produce structurally perfect crystals. Modern utilizations of substances in electronics, such as radio transmitters and high frequency microphones, often require single crystals with controlled purity and structural perfection. The near convectionless environment of silica gel suppresses nucleation, thereby reducing the competitive nature of crystal growth. This competition limits the size and perfection of the crystal; and it is obviously desirable to suppress nucleation until, ideally, only one crystal grows in a predetermined location. A silica gel is not a completely convectionless environment like outer space, but is the closest known environment to that of outer space that can be created on Earth.

  7. Silica precipitation with synthetic silaffin peptides.

    PubMed

    Wieneke, Ralph; Bernecker, Anja; Riedel, Radostan; Sumper, Manfred; Steinem, Claudia; Geyer, Armin

    2011-08-01

    Silaffins are highly charged proteins which are one of the major contributing compounds that are thought to be responsible for the formation of the hierarchically structured silica-based cell walls of diatoms. Here we describe the synthesis of an oligo-propyleneamine substituted lysine derivative and its incorporation into the KXXK peptide motif occurring repeatedly in silaffins. N(ε)-alkylation of lysine was achieved by a Mitsunobu reaction to obtain a protected lysine derivative which is convenient for solid phase peptide synthesis. Quantitative silica precipitation experiments together with structural information about the precipitated silica structures gained by scanning electron microscopy revealed a dependence of the amount and form of the silica precipitates on the peptide structure. PMID:21674108

  8. Nanoparticle-doped radioluminescent silica optical fibers

    NASA Astrophysics Data System (ADS)

    Mrazek, J.; Nikl, M.; Kasik, I.; Podrazky, O.; Aubrecht, J.; Beitlerova, A.

    2014-05-01

    This contribution deals with the preparation and characterization of the silica optical fibers doped by nanocrystalline zinc silicate. The sol-gel approach was employed to prepare colloidal solution of zinc silicate precursors. Prepared sol was thermally treated to form nanocrystalline zinc silicate disperzed inside amorphous silica matrix or soaked inside the porous silica frit deposed inside the silica substrate tube which was collapsed into preform and drawn into optical fiber. Single mode optical fiber with the core diameter 15 μm and outer diamer 125 μm was prepared. Optical and waveguiding properties of the fiber were analyzed. Concentration of the zinc silicate in the fiber was 0.93 at. %. Radioluminescence properties of nanocrystalline zinc silicate powder and of the prepared optical fiber were investigated. The nanoparticle doped samples appear a emission maximum at 390 nm.

  9. Silica Transport and Cementation in Quartz Aggregates

    NASA Astrophysics Data System (ADS)

    Pebble, C.; Farver, J.; Onasch, C.; Winslow, D.

    2008-12-01

    Silica transport and cementation in quartz aggregates have been experimentally investigated. Starting materials include a natural quartz arenite (Pocono sandstone), sized clasts of synthetic quartz, and sized grains of disaggregated natural sandstones. Experimental charges consisted of amorphous silica powder (~25 mg), AlCl3 powder (~3 mg), 25 wt% NaCl brine solution (~20 mg), and the starting material (~150 mg). The charges were weld-sealed in gold capsules and run in cold-seal pressure vessels at 300°C to 600°C at 150 MPa confining pressure for up to 4 weeks. Detailed calibrations of the furnaces indicate the maximum temperature variation across the length of the sample charges (3-7mm) was <5°C, and typically <3°C. After the experiments, samples were vacuum impregnated with epoxy containing a blue dye and sawn in half along the long axis of the sample charge. The nature and amount of silica transport and cementation in the samples was determined by a combination of Cathodoluminescence (CL), Light Microscopy (LM), and Scanning Electron Microscopy (SEM). Photomosaics of the samples were collected and the amount of cement, porosity, and average grain sizes were determined by point-counting. The cement was easily recognized from the quartz grains by the difference in luminescence. The experiments indicate that the presence of amorphous silica results in rapid silica cementation in quartz aggregates (e.g., up to 12% cement by volume in 4 weeks at 450°C). The amount of cementation is a function of substrate type, time, temperature, and ionic strength of the brine. The rate of silica transport through the length of the experimental charge appears to be limited by the silica solubility and its rapid depletion by cementation. Although most of the cement was derived from the amorphous silica, evidence for local dissolution-precipitation was observed. The experiments demonstrate that the mobility of silica, and consequent precipitation of cement, does not require a

  10. OCCUPATIONAL SILICA EXPOSURE AND CHRONIC KIDNEY DISEASE

    PubMed Central

    Vupputuri, Suma; Parks, Christine G.; Nylander-French, Leena A.; Owen-Smith, Ashli; Hogan, Susan L.; Sandler, Dale P.

    2012-01-01

    Introduction Occupational exposure to silica may be associated with chronic kidney disease (CKD). Most studies have been conducted in occupational cohorts with high levels of exposure but small numbers of cases. We analyzed data from a population-based case-control study of occupational silica exposure and CKD. Methods Cases were hospital patients with newly diagnosed CKD and community controls were selected using random digit dialing and frequency matched by age, gender, race and proximity to the hospital. Silica exposure estimates were assigned by industrial hygiene review of lifetime job history data and weighted for certainty and intensity. Conditional logistic regression was used to estimate the odds ratios (ORs) for CKD conditioned on demographic, lifestyle and clinical variables. Results The mean age of participants was 62 years (range, 30-83 years), 56% were male and 54% were white. Any silica exposure (compared to none) was associated with a 40% increased risk of CKD (OR=1.40, 95% confidence interval [CI]: 1.04, 1.89) in a multivariable adjusted model. The mean cumulative duration of silica exposure was significantly higher in exposed cases than in exposed controls (33.4 vs. 24.8 years, respectively). Overall, compared to non-exposed participants, the ORs (95% CI) for those below and above the median duration of silica exposure were 1.20 (95% CI: 0.77, 1.86) and 1.76 (95% CI: 1.14, 2.71), respectively. Conclusions We found a positive relationship between occupational silica exposure and CKD. A dose-response trend of increasing CKD risk with increasing duration of silica exposure was observed and was particularly strong among non-whites. PMID:22032652

  11. Silica Aerogel Captures Cosmic Dust Intact

    NASA Technical Reports Server (NTRS)

    Tsou, P.

    1994-01-01

    The mesostructure of silica aerogel resembles stings of grapes, ranging in size from 10 to 100 angstrom. This fine mesostructure transmits nearly 90 percent of incident light in the visible, while providing sufficiently gentle dissipation of the kinetric energy of hypervelocity cosmic dust particles to permit their intact capture. We introduced silica aerogel in 1987 as capture medium to take advantage of its low density, fine mesostruicture and most importantly, its transparency, allowing optical location of captured micron sized particles.

  12. Optical shock waves in silica aerogel.

    PubMed

    Gentilini, S; Ghajeri, F; Ghofraniha, N; Di Falco, A; Conti, C

    2014-01-27

    Silica aerogels are materials well suited for high power nonlinear optical applications. In such regime, the non-trivial thermal properties may give rise to the generation of optical shock waves, which are also affected by the structural disorder due to the porous solid-state gel. Here we report on an experimental investigation in terms of beam waist and input power, and identify various regimes of the generation of wave-breaking phenomena in silica aerogels. PMID:24515173

  13. Grazers: biocatalysts of terrestrial silica cycling.

    PubMed

    Vandevenne, Floor Ina; Barão, Ana Lúcia; Schoelynck, Jonas; Smis, Adriaan; Ryken, Nick; Van Damme, Stefan; Meire, Patrick; Struyf, Eric

    2013-12-01

    Silica is well known for its role as inducible defence mechanism countering herbivore attack, mainly through precipitation of opaline, biogenic silica (BSi) bodies (phytoliths) in plant epidermal tissues. Even though grazing strongly interacts with other element cycles, its impact on terrestrial silica cycling has never been thoroughly considered. Here, BSi content of ingested grass, hay and faeces of large herbivores was quantified by performing multiple chemical extraction procedures for BSi, allowing the assessment of chemical reactivity. Dissolution experiments with grass and faeces were carried out to measure direct availability of BSi for dissolution. Average BSi and readily soluble silica numbers were higher in faeces as compared with grass or hay, and differences between herbivores could be related to distinct digestive strategies. Reactivity and dissolvability of BSi increases after digestion, mainly due to degradation of organic matrices, resulting in higher silica turnover rates and mobilization potential from terrestrial to aquatic ecosystems in non-grazed versus grazed pasture systems (2 versus 20 kg Si ha(-1) y(-1)). Our results suggest a crucial yet currently unexplored role of herbivores in determining silica export from land to ocean, where its availability is linked to eutrophication events and carbon sequestration through C-Si diatom interactions. PMID:24107532

  14. Grazers: biocatalysts of terrestrial silica cycling

    PubMed Central

    Vandevenne, Floor Ina; Barão, Ana Lúcia; Schoelynck, Jonas; Smis, Adriaan; Ryken, Nick; Van Damme, Stefan; Meire, Patrick; Struyf, Eric

    2013-01-01

    Silica is well known for its role as inducible defence mechanism countering herbivore attack, mainly through precipitation of opaline, biogenic silica (BSi) bodies (phytoliths) in plant epidermal tissues. Even though grazing strongly interacts with other element cycles, its impact on terrestrial silica cycling has never been thoroughly considered. Here, BSi content of ingested grass, hay and faeces of large herbivores was quantified by performing multiple chemical extraction procedures for BSi, allowing the assessment of chemical reactivity. Dissolution experiments with grass and faeces were carried out to measure direct availability of BSi for dissolution. Average BSi and readily soluble silica numbers were higher in faeces as compared with grass or hay, and differences between herbivores could be related to distinct digestive strategies. Reactivity and dissolvability of BSi increases after digestion, mainly due to degradation of organic matrices, resulting in higher silica turnover rates and mobilization potential from terrestrial to aquatic ecosystems in non-grazed versus grazed pasture systems (2 versus 20 kg Si ha−1 y−1). Our results suggest a crucial yet currently unexplored role of herbivores in determining silica export from land to ocean, where its availability is linked to eutrophication events and carbon sequestration through C–Si diatom interactions. PMID:24107532

  15. Transport of colloidal silica in unsaturated sand: Effect of charging properties of sand and silica particles.

    PubMed

    Fujita, Yosuke; Kobayashi, Motoyoshi

    2016-07-01

    We have studied the transport of colloidal silica in various degrees of a water-saturated Toyoura sand column, because silica particles are widely used as catalyst carriers and abrasive agents, and their toxicity is reported recently. Since water-silica, water-sand, and air-water interfaces have pH-dependent negative charges, the magnitude of surface charge was controlled by changing the solution pH. The results show that, at high pH conditions (pH 7.4), the deposition of colloidal silica to the sand surface is interrupted and the silica concentration at the column outlet immediately reaches the input concentration in saturated conditions. In addition, the relative concentration of silica at the column outlet only slightly decreases to 0.9 with decreasing degrees of water saturation to 38%, because silica particles are trapped in straining regions in the soil pore and air-water interface. On the other hand, at pH 5 conditions (low pH), where sand and colloid have less charge, reduced repulsive forces result in colloidal silica attaching onto the sand in saturated conditions. The deposition amount of silica particles remarkably increases with decreasing degrees of water saturation to 37%, which is explained by more particles being retained in the sand column associated with the air-water interface. In conclusion, at higher pH, the mobility of silica particles is high, and the air-water interface is inactive for the deposition of silica. On the other hand, at low pH, the deposition amount increases with decreasing water saturation, and the particle transport is inhibited. PMID:27045635

  16. Silica ecosystem for synergistic biotransformation

    PubMed Central

    Mutlu, Baris R.; Sakkos, Jonathan K.; Yeom, Sujin; Wackett, Lawrence P.; Aksan, Alptekin

    2016-01-01

    Synergistical bacterial species can perform more varied and complex transformations of chemical substances than either species alone, but this is rarely used commercially because of technical difficulties in maintaining mixed cultures. Typical problems with mixed cultures on scale are unrestrained growth of one bacterium, which leads to suboptimal population ratios, and lack of control over bacterial spatial distribution, which leads to inefficient substrate transport. To address these issues, we designed and produced a synthetic ecosystem by co-encapsulation in a silica gel matrix, which enabled precise control of the microbial populations and their microenvironment. As a case study, two greatly different microorganisms: Pseudomonas sp. NCIB 9816 and Synechococcus elongatus PCC 7942 were encapsulated. NCIB 9816 can aerobically biotransform over 100 aromatic hydrocarbons, a feat useful for synthesis of higher value commodity chemicals or environmental remediation. In our system, NCIB 9816 was used for biotransformation of naphthalene (a model substrate) into CO2 and the cyanobacterium PCC 7942 was used to provide the necessary oxygen for the biotransformation reactions via photosynthesis. A mathematical model was constructed to determine the critical cell density parameter to maximize oxygen production, and was then used to maximize the biotransformation rate of the system. PMID:27264916

  17. Silica ecosystem for synergistic biotransformation.

    PubMed

    Mutlu, Baris R; Sakkos, Jonathan K; Yeom, Sujin; Wackett, Lawrence P; Aksan, Alptekin

    2016-01-01

    Synergistical bacterial species can perform more varied and complex transformations of chemical substances than either species alone, but this is rarely used commercially because of technical difficulties in maintaining mixed cultures. Typical problems with mixed cultures on scale are unrestrained growth of one bacterium, which leads to suboptimal population ratios, and lack of control over bacterial spatial distribution, which leads to inefficient substrate transport. To address these issues, we designed and produced a synthetic ecosystem by co-encapsulation in a silica gel matrix, which enabled precise control of the microbial populations and their microenvironment. As a case study, two greatly different microorganisms: Pseudomonas sp. NCIB 9816 and Synechococcus elongatus PCC 7942 were encapsulated. NCIB 9816 can aerobically biotransform over 100 aromatic hydrocarbons, a feat useful for synthesis of higher value commodity chemicals or environmental remediation. In our system, NCIB 9816 was used for biotransformation of naphthalene (a model substrate) into CO2 and the cyanobacterium PCC 7942 was used to provide the necessary oxygen for the biotransformation reactions via photosynthesis. A mathematical model was constructed to determine the critical cell density parameter to maximize oxygen production, and was then used to maximize the biotransformation rate of the system. PMID:27264916

  18. Silica ecosystem for synergistic biotransformation

    NASA Astrophysics Data System (ADS)

    Mutlu, Baris R.; Sakkos, Jonathan K.; Yeom, Sujin; Wackett, Lawrence P.; Aksan, Alptekin

    2016-06-01

    Synergistical bacterial species can perform more varied and complex transformations of chemical substances than either species alone, but this is rarely used commercially because of technical difficulties in maintaining mixed cultures. Typical problems with mixed cultures on scale are unrestrained growth of one bacterium, which leads to suboptimal population ratios, and lack of control over bacterial spatial distribution, which leads to inefficient substrate transport. To address these issues, we designed and produced a synthetic ecosystem by co-encapsulation in a silica gel matrix, which enabled precise control of the microbial populations and their microenvironment. As a case study, two greatly different microorganisms: Pseudomonas sp. NCIB 9816 and Synechococcus elongatus PCC 7942 were encapsulated. NCIB 9816 can aerobically biotransform over 100 aromatic hydrocarbons, a feat useful for synthesis of higher value commodity chemicals or environmental remediation. In our system, NCIB 9816 was used for biotransformation of naphthalene (a model substrate) into CO2 and the cyanobacterium PCC 7942 was used to provide the necessary oxygen for the biotransformation reactions via photosynthesis. A mathematical model was constructed to determine the critical cell density parameter to maximize oxygen production, and was then used to maximize the biotransformation rate of the system.

  19. Silica-metal core-shell nanostructures.

    PubMed

    Jankiewicz, B J; Jamiola, D; Choma, J; Jaroniec, M

    2012-01-15

    Silica-metal nanostructures consisting of silica cores and metal nanoshells attract a lot of attention because of their unique properties and potential applications ranging from catalysis and biosensing to optical devices and medicine. The important feature of these nanostructures is the possibility of controlling their properties by the variation of their geometry, shell morphology and shell material. This review is devoted to silica-noble metal core-shell nanostructures; specifically, it outlines the main methods used for the preparation and surface modification of silica particles and presents the major strategies for the formation of metal nanoshells on the modified silica particles. A special emphasis is given to the Stöber method, which is relatively simple, effective and well verified for the synthesis of large and highly uniform silica particles (with diameters from 100 nm to a few microns). Next, the surface chemistry of these particles is discussed with a special focus on the attachment of specific organic groups such as aminopropyl or mercaptopropyl groups, which interact strongly with metal species. Finally, the synthesis, characterization and application of various silica-metal core-shell nanostructures are reviewed, especially in relation to the siliceous cores with gold or silver nanoshells. Nowadays, gold is most often used metal for the formation of nanoshells due to its beneficial properties for many applications. However, other metals such as silver, platinum, palladium, nickel and copper were also used for fabrication of core-shell nanostructures. Silica-metal nanostructures can be prepared using various methods, for instance, (i) growth of metal nanoshells on the siliceous cores with deposited metal nanoparticles, (ii) reduction of metal species accompanied by precipitation of metal nanoparticles on the modified silica cores, and (iii) formation of metal nanoshells under ultrasonic conditions. A special emphasis is given to the seed

  20. Skeletal silica characterization in porous-silica low-dielectric-constant films by infrared spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Takada, Syozo; Hata, Nobuhiro; Seino, Yutaka; Fujii, Nobutoshi; Kikkawa, Takamaro

    2005-06-01

    Porous-silica low-dielectric-constant (low-k) films were prepared using a sol-gel method based on the self-assembly of surfactant templates. No change in the refractive index at 633 nm nor in the infrared-absorption intensities of C-H and O-H stretching vibrations at around 2900 and 3400cm-1 of porous-silica low-k films were observed after annealing at each temperature from 523 to 723 K. On the other hand, the Young's elastic modulus and hardness increased with the increase of annealing temperature. The structure in the complex dielectric function of porous-silica low-k films observed in between 1000 and 1400cm-1 is assigned as the asymmetric stretching vibration mode of the Si-O-Si bond. By applying the effective-medium theory by Bruggeman to the experimental results from infrared spectroscopic ellipsometry, we analyzed the skeletal silica structures. The peak positions of transverse (ωTO) and longitudinal (ωLO) vibration modes for Si-O-Si network in the silica skeleton of porous-silica films changed from 1061 to 1068cm-1 and from 1219 to 1232cm-1, respectively, with the annealing temperature. It is shown that the ωLO2/ωTO2 of skeletal silica correlates with Young's elastic modulus of porous-silica low-k films.

  1. The Management of Silica in Los Alamos National Laboratory Tap Water - A Study of Silica Solubility

    SciTech Connect

    Wohlberg, C.; Worland, V.P.; Kozubal, M.A.; Erickson, G.F.; Jacobson, H.M.; McCarthy, K.T.

    1999-07-01

    Well water at Los Alamos National Laboratory (LANL) has a silica (SiO{sub 2}) content of 60 to 100 mg/L, with 4 mg/L of magnesium, 13 mg/L calcium and lesser concentrations of other ions. On evaporation in cooling towers, when the silica concentration reaches 150 to 220 mg/L, silica deposits on heat transfer surfaces. When the high silica well water is used in the reprocessing of plutonium, silica remains in solution at the end of the process and creates a problem of removal from the effluent prior to discharge or evaporation. The work described in this Report is divided into two major parts. The first part describes the behavior of silica when the water is evaporated at various conditions of pH and in the presence of different classes of anions: inorganic and organic. In the second part of this work it was found that precipitation (floccing) of silica was a function of solution pH and mole ratio of metal to silica.

  2. Synthesis and Characterization of Bionanoparticle-Silica Composites and Mesoporous Silica with Large Pores

    SciTech Connect

    Niu, Z.; Yang, L.; Kabisatpathy, S.; He, J.; Lee, A.; Ron, J.; Sikha, G.; Popov, B.N.; Emrick, T.; Russell, T. P.; Wang. Q.

    2009-03-24

    A sol-gel process has been developed to incorporate bionanoparticles, such as turnip yellow mosaic virus, cowpea mosaic virus, tobacco mosaic virus, and ferritin into silica, while maintaining the integrity and morphology of the particles. The structures of the resulting materials were characterized by transmission electron microscopy, small angle X-ray scattering, and N{sub 2} adsorption-desorption analysis. The results show that the shape and surface morphology of the bionanoparticles are largely preserved after being embedded into silica. After removal of the bionanoparticles by calcination, mesoporous silica with monodisperse pores, having the shape and surface morphology of the bionanoparticles replicated inside the silica, was produced,. This study is expected to lead to both functional composite materials and mesoporous silica with structurally well-defined large pores.

  3. Comparative Investigation on Thermal Insulation of Polyurethane Composites Filled with Silica Aerogel and Hollow Silica Microsphere.

    PubMed

    Liu, Chunyuan; Kim, Jin Seuk; Kwon, Younghwan

    2016-02-01

    This paper presents a comparative study on thermal conductivity of PU composites containing open-cell nano-porous silica aerogel and closed-cell hollow silica microsphere, respectively. The thermal conductivity of PU composites is measured at 30 degrees C with transient hot bridge method. The insertion of polymer in pores of silica aerogel creates mixed interfaces, increasing the thermal conductivity of resulting composites. The measured thermal conductivity of PU composites filled with hollow silica microspheres is estimated using theoretical models, and is in good agreement with Felske model. It appears that the thermal conductivity of composites decreases with increasing the volume fraction (phi) when hollow silica microsphere (eta = 0.916) is used. PMID:27433652

  4. Silica-based cationic bilayers as immunoadjuvants

    PubMed Central

    Lincopan, Nilton; Santana, Mariana RA; Faquim-Mauro, Eliana; da Costa, Maria Helena B; Carmona-Ribeiro, Ana M

    2009-01-01

    Background Silica particles cationized by dioctadecyldimethylammonium bromide (DODAB) bilayer were previously described. This work shows the efficiency of these particulates for antigen adsorption and presentation to the immune system and proves the concept that silica-based cationic bilayers exhibit better performance than alum regarding colloid stability and cellular immune responses for vaccine design. Results Firstly, the silica/DODAB assembly was characterized at 1 mM NaCl, pH 6.3 or 5 mM Tris.HCl, pH 7.4 and 0.1 mg/ml silica over a range of DODAB concentrations (0.001–1 mM) by means of dynamic light scattering for particle sizing and zeta-potential analysis. 0.05 mM DODAB is enough to produce cationic bilayer-covered particles with good colloid stability. Secondly, conditions for maximal adsorption of bovine serum albumin (BSA) or a recombinant, heat-shock protein from Mycobacterium leprae (18 kDa-hsp) onto DODAB-covered or onto bare silica were determined. At maximal antigen adsorption, cellular immune responses in vivo from delayed-type hypersensitivity reactions determined by foot-pad swelling tests (DTH) and cytokines analysis evidenced the superior performance of the silica/DODAB adjuvant as compared to alum or antigens alone whereas humoral response from IgG in serum was equal to the one elicited by alum as adjuvant. Conclusion Cationized silica is a biocompatible, inexpensive, easily prepared and possibly general immunoadjuvant for antigen presentation which displays higher colloid stability than alum, better performance regarding cellular immune responses and employs very low, micromolar doses of cationic and toxic synthetic lipid. PMID:19152701

  5. Hard magnetism in structurally engineered silica nanocomposite.

    PubMed

    Song, Hyon-Min; Zink, Jeffrey I

    2016-09-21

    Creation of structural complexity by simple experimental control will be an attractive approach for the preparation of nanomaterials, as a classical bottom-up method is supplemented by a more efficient and more direct artificial engineering method. In this study, structural manipulation of MCM-41 type mesoporous silica is investigated by generating and imbedding hard magnetic CoFe2O4 nanoparticles into mesoporous silica. Depending on the heating rate and target temperature, mesoporous silica undergoes a transformation in shape to form hollow silica, framed silica with interior voids, or melted silica with intact mesostructures. Magnetism is governed by the major CoFe2O4 phase, and it is affected by antiferromagnetic hematite (α-Fe2O3) and olivine-type cobalt silicate (Co2SiO4), as seen in its paramagnetic behavior at the annealing temperature of 430 °C. The early formation of Co2SiO4 than what is usually observed implies the effect of the partial substitution of Fe in the sites of Co. Under slow heating (2.5 °C min(-1)) mesostructures are preserved, but with significantly smaller mesopores (d100 = 1.5 nm). In addition, nonstoichiometric CoxFe1-xO with metal vacancies at 600 °C, and spinel Co3O4 at 700 °C accompany major CoFe2O4. The amorphous nature of silica matrix is thought to contribute significantly to these structurally diverse and rich phases, enabled by off-stoichiometry between Si and O, and accelerated by the diffusion of metal cations into SiO4 polyhedra at an elevated temperature. PMID:27537252

  6. Subsurface defect characterization and laser-induced damage performance of fused silica optics polished with colloidal silica and ceria

    NASA Astrophysics Data System (ADS)

    Xiang, He; Gang, Wang; Heng, Zhao; Ping, Ma

    2016-04-01

    This paper mainly focuses on the influence of colloidal silica polishing on the damage performance of fused silica optics. In this paper, nanometer sized colloidal silica and micron sized ceria are used to polish fused silica optics. The colloidal silica polished samples and ceria polished samples exhibit that the root-mean-squared (RMS) average surface roughness values are 0.7 nm and 1.0 nm, respectively. The subsurface defects and damage performance of the polished optics are analyzed and discussed. It is revealed that colloidal silica polishing will introduce much fewer absorptive contaminant elements and subsurface damages especially no trailing indentation fracture. The 355-nm laser damage test reveals that each of the fused silica samples polished with colloidal silica has a much higher damage threshold and lower damage density than ceria polished samples. Colloidal silica polishing is potential in manufacturing high power laser optics.

  7. Re-evaluation of total and Umkehr ozone data from NOAA-CMDL Dobson spectrophotometer observatories. Final report

    SciTech Connect

    Komhyr, W.D.; Quincy, D.M.; Grass, R.D.; Koenig, G.L. |

    1995-12-01

    This report describes work to improve the quality of total ozone and Umkehr data obtained in the past at the NOAA Climate Monitoring and Diagnostics Laboratory and the Dobson spectrophotometer ozone observatories. The authors present results of total ozone data re-evaluations for ten stations: Byrd, Antarctica; Fairbanks, Alaska; Hallett, Antarctica; Huancayo, Peru; Haute Provence, France; Lauder, New Zealand; Perth, Australia; Poker Flat, Alaska; Puerto Montt, Chile; and South Pole, Antarctica. The improved data will be submitted in early 1996 to the World Meteorological Organization (WMO) World Ozone Data Center (WODC), and the Atmospheric Environment Service for archiving. Considerable work has been accomplished, also, in reevaluating Umkehr data from seven of the stations, viz., Huancayo, Haute Provence, Lauder, Perth, Poker Flat, Boulder, Colorado; and Mauna Loa, Hawaii.

  8. A re-evaluation of the Moyuta geothermal system, Southern Guatemala

    SciTech Connect

    Goff, F.; Adams, A.; Trujillo, P.E.; Counce, D. ); Janik, C.; Fahlquist, L. ); Roldan, A.; Revolorio, M. . Unidad de Desarollo Geotermico)

    1991-01-01

    Chemical and isotopic data from four fumarole sites combined with prefeasibility assessments obtained in the 1970s have resulted in a re-evaluation of the Moyuta geothermal system. Moyuta consists of an east-west trending complex of Quaternary andesite/dacite domes and flows cut by north-trending faults. Areas of fumaroles, acid springs, and bicarbonate-rich thermal springs flank the north and south sides of the volcanic complex. Chloride-rich thermal springs discharge along rivers at lower elevations around the Moyuta highland. The distribution of thermal features indicates that deep reservoir fluid rises convectively near the axis of volcanism. Geochemical data suggest that there are two subsystems having temperatures of about 210{degrees}C (north flank) and 170{degrees}C (south flank). Exploration wells sited near the most northerly fumarole (Azulco) achieved temperatures of {le}113{degrees}C at 1004 m depth. We suggest the fumaroles occur above hydrothermal outflow plumes confined to vertical, fault-controlled conduits. Better drilling sites occur closer to the intersections of the north trending faults and the Quaternary volcanic axis. 21 refs., 7 figs., 2 tabs.

  9. Re-evaluation and updating of the seismic hazard of Lebanon

    NASA Astrophysics Data System (ADS)

    Huijer, Carla; Harajli, Mohamed; Sadek, Salah

    2016-01-01

    This paper presents the results of a study undertaken to evaluate the implications of the newly mapped offshore Mount Lebanon Thrust (MLT) fault system on the seismic hazard of Lebanon and the current seismic zoning and design parameters used by the local engineering community. This re-evaluation is critical, given that the MLT is located at close proximity to the major cities and economic centers of the country. The updated seismic hazard was assessed using probabilistic methods of analysis. The potential sources of seismic activities that affect Lebanon were integrated along with any/all newly established characteristics within an updated database which includes the newly mapped fault system. The earthquake recurrence relationships of these sources were developed from instrumental seismology data, historical records, and earlier studies undertaken to evaluate the seismic hazard of neighboring countries. Maps of peak ground acceleration contours, based on 10 % probability of exceedance in 50 years (as per Uniform Building Code (UBC) 1997), as well as 0.2 and 1 s peak spectral acceleration contours, based on 2 % probability of exceedance in 50 years (as per International Building Code (IBC) 2012), were also developed. Finally, spectral charts for the main coastal cities of Beirut, Tripoli, Jounieh, Byblos, Saida, and Tyre are provided for use by designers.

  10. Re-evaluation of the culture condition of polymorphonuclear cells for the study of apoptosis induction.

    PubMed

    Hiroi, M; Tajima, M; Shimojima, T; Kashimata, M; Miyata, T; Sakagami, H

    1998-01-01

    The culture conditions of human peripheral blood polymorphonuclear leukocytes (PMN) in the study of apoptosis induction were re-evaluated. The changes in the relative viable cell number of PMNs after tumor necrosis factor (TNF) treatment were colorimetrically investigated using a cell counting kit. The relative potency of PMNs to produce the superoxide anion (O2-) was measured as the reduction of color intensity by addition of superoxide dismutase (SOD). When the PMNs were cultured in conventional RPMI1640 medium supplemented with 10% fetal bovine serum (FBS), the stimulation effect of TNF on O2- generation by PMNs was observed only for the first 6 hours. When FBS was replaced with human serum, the effect of TNF was maintained for longer incubation periods. Prolonged incubation of PMNs spontaneously produced large DNA fragments, and the extent of DNA fragmentation was relatively smaller in human serum-containing medium. TNF, LPS, hyperthermia or potassium thiocyanate slightly accelerated the production of large DNA fragments, as well as the induction of trace amounts of internucleosomal DNA cleavage in PMNs, which became detectable only after concentration by fractional isopropanol precipitation. The present study suggests the importance of the use of human serum rather than conventional FBS for the study of apoptosis induction in PMNs. PMID:9673409