Science.gov

Sample records for natural solution concept

  1. Naturally selecting solutions

    PubMed Central

    Manning, Timmy; Sleator, Roy D; Walsh, Paul

    2013-01-01

    For decades, computer scientists have looked to nature for biologically inspired solutions to computational problems; ranging from robotic control to scheduling optimization. Paradoxically, as we move deeper into the post-genomics era, the reverse is occurring, as biologists and bioinformaticians look to computational techniques, to solve a variety of biological problems. One of the most common biologically inspired techniques are genetic algorithms (GAs), which take the Darwinian concept of natural selection as the driving force behind systems for solving real world problems, including those in the bioinformatics domain. Herein, we provide an overview of genetic algorithms and survey some of the most recent applications of this approach to bioinformatics based problems. PMID:23222169

  2. On the Nature of Concepts.

    ERIC Educational Resources Information Center

    Ninnes, L. E.

    It is difficult to give a precise meaning to the term "concept" because to specify any sense to the term is already to be using concepts. It is impossible to talk about concepts without at the same time having made epistemological and metaphysical commitments. If the epistemological and metaphysical commitments are inadequate, then the…

  3. Concept analysis: some limitations and possible solutions.

    PubMed

    Botes, A

    2002-08-01

    Concepts are the basic building blocks of scientific knowledge or theoretical frameworks for any discipline. The strength of the theories that guide a discipline is dependent on the quality of the concept analysis. Thus, the utilisation of poorly understood concepts in research and theory development will result in questionable reliability and validity. Concept analysis is associated with the research design of philosophical inquiry. The purpose of philosophical inquiry is to perform research using intellectual analysis to clarify meaning. Traditionally, no empirical (qualitative or quantitative) investigations were used to clarify the meaning of concepts. The lack of empirical investigation to clarify concepts, results in certain limitations in the methodology of concept analysis. It seems that methodological innovations for enhancing concept analysis is urgently required. The purpose of this article is to describe the utilisation of qualitative and quantitative strategies with literature review in concept analysis as a possible solution to limitations. This article will firstly, describe the limitations in the traditional Wilsonian methods of concept analysis and will secondly demonstrate how the introduction of qualitative and quantitative methods with literature review can overcome some of the limitations. An example a research study on quality of life (Ferrans, 1997:110) will be used to demonstrate how qualitative and quantitative empirical methods with literature review can enhance the quality of concept analysis.

  4. A natural species concept for prokaryotes

    NASA Technical Reports Server (NTRS)

    Ward, D. M.

    1998-01-01

    Direct molecular analyses of natural microbial populations reveal patterns that should compel microbiologists to adopt a more natural species concept that has been known to biologists for decades. The species debate can be exploited to address a larger issue - microbiologists need, in general, to take a more natural view of the organisms they study.

  5. Childrens' Conceptions of Nature

    ERIC Educational Resources Information Center

    Payne, Phillip

    2014-01-01

    This paper describes a study of sixth grade children's conceptions of nature and the environment. In so doing, it asks that environmental educators pay more attention to children's preconceived notions of environment and nature. Should this occur the theory-practice gap in environmental education may be diminished. Learners' concept…

  6. Missing concepts in natural selection theory reconstructions.

    PubMed

    Ginnobili, Santiago

    2016-09-01

    The concept of fitness has generated a lot of discussion in philosophy of biology. There is, however, relative agreement about the need to distinguish at least two uses of the term: ecological fitness on the one hand, and population genetics fitness on the other. The goal of this paper is to give an explication of the concept of ecological fitness by providing a reconstruction of the theory of natural selection in which this concept was framed, that is, based on the way the theory was put to use in Darwin's main texts. I will contend that this reconstruction enables us to account for the current use of the theory of natural selection. The framework presupposed in the analysis will be that of metatheoretical structuralism. This framework will provide both a better understanding of the nature of ecological fitness and a more complete reconstruction of the theory. In particular, it will provide what I think is a better way of understanding how the concept of fitness is applied through heterogeneous cases. One of the major advantages of my way of thinking about natural selection theory is that it would not have the peculiar metatheoretical status that it has in other available views. I will argue that in order to achieve these goals it is necessary to make several concepts explicit, concepts that are frequently omitted in usual reconstructions.

  7. Nature, Human Nature, and Solutions to Problems.

    ERIC Educational Resources Information Center

    Pedrini, D. T.; Pedrini, B. C.

    This paper promotes an undergraduate course that would discuss the great ideas of Plato, St. Paul, Karl Marx, Sigmund Freud, Jean Paul Sartre, B. F. Skinner, and Konrad Lorenz. This course would help students understand human values and behaviors while focusing on historical, world, and national problems. Tentative solutions would then be…

  8. Student conceptions of the nature of science

    NASA Astrophysics Data System (ADS)

    Talbot, Amanda L.

    Research has shown that students from elementary school to college have major misconceptions about the nature of science. While an appropriate understanding of the nature of science has been an objective of science education for a century, researchers using a variety of instruments, continue to document students' inadequate conceptions of what science is and how it operates as an enterprise. Current research involves methods to improve student understanding of the nature of science. Students often misunderstand the creative, subjective, empirical, and tentative nature of science. They do not realize the relationship between laws and theories, nor do they understand that science does not follow a prescribed method. Many do not appreciate the influence culture, society, and politics; nor do they have an accurate understanding of the types of questions addressed by science. This study looks at student understanding of key nature of science (NOS) concepts in order to examine the impact of implementing activities intended to help students better understand the process of science and to see if discussion of key NOS concepts following those activities will result in greater gains in NOS understanding. One class received an "activities only" treatment, while the other participated in the same activities followed by explicit discussion of key NOS themes relating to the activity. The interventions were implemented for one school year in two high school anatomy and physiology courses composed of juniors and seniors. Student views of the nature of science were measured using the Views of the Nature of Science-Form C (VNOS-C). Students in both classes demonstrated significant gains in NOS understanding. However, contrary to current research, the addition of explicit discussion did not result in significantly greater gains in NOS understanding. This suggests that perhaps students in higher-level science classes can draw the correlations between NOS related activities and

  9. Portable long trace profiler: Concept and solution

    NASA Astrophysics Data System (ADS)

    Qian, Shinan; Takacs, Peter; Sostero, Giovanni; Cocco, Daniele

    2001-08-01

    Since the early development of the penta-prism long trace profiler (LTP) and the in situ LTP, and following the completion of the first in situ distortion profile measurements at Sincrotrone Trieste (ELETTRA) in Italy in 1995, a concept was developed for a compact, portable LTP with the following characteristics: easily installed on synchrotron radiation beam lines, easily carried to different laboratories around the world for measurements and calibration, convenient for use in evaluating the LTP as an in-process tool in the optical workshop, and convenient for use in temporarily installation as required by other special applications. The initial design of a compact LTP optical head was made at ELETTRA in 1995. Since 1997 further efforts to reduce the optical head size and weight, and to improve measurement stability have been made at Brookhaven National Laboratory. This article introduces the following solutions and accomplishments for the portable LTP: (1) a new design for a compact and very stable optical head, (2) the use of a small detector connected to a laptop computer directly via an enhanced parallel port, and there is no extra frame grabber interface and control box, (3) a customized small mechanical slide that uses a compact motor with a connector-sized motor controller, and (4) the use of a laptop computer system. These solutions make the portable LTP able to be packed into two laptop-size cases: one for the computer and one for the rest of the system.

  10. A Review of Solution Chemistry Studies: Insights into Students' Conceptions

    ERIC Educational Resources Information Center

    Calyk, Muammer; Ayas, Alipa; Ebenezer, Jazlin V.

    2005-01-01

    This study has reviewed the last two decades of student conception research in solution chemistry pertaining to aims, methods of exploring students' conception, general knowledge claims, students' conceptions and difficulties, and conceptual change studies. The aims of solution chemistry studies have been to assess students' understanding level of…

  11. Natural tuning: towards a proof of concept

    NASA Astrophysics Data System (ADS)

    Dubovsky, Sergei; Gorbenko, Victor; Mirbabayi, Mehrdad

    2013-09-01

    The cosmological constant problem and the absence of new natural physics at the electroweak scale, if confirmed by the LHC, may either indicate that the nature is fine-tuned or that a refined notion of naturalness is required. We construct a family of toy UV complete quantum theories providing a proof of concept for the second possibility. Low energy physics is described by a tuned effective field theory, which exhibits relevant interactions not protected by any symmetries and separated by an arbitrary large mass gap from the new "gravitational" physics, represented by a set of irrelevant operators. Nevertheless, the only available language to describe dynamics at all energy scales does not require any fine-tuning. The interesting novel feature of this construction is that UV physics is not described by a fixed point, but rather exhibits asymptotic fragility. Observation of additional unprotected scalars at the LHC would be a smoking gun for this scenario. Natural tuning also favors TeV scale unification.

  12. Exploring the folkbiological conception of human nature

    PubMed Central

    Linquist, Stefan; Machery, Edouard; Griffiths, Paul E.; Stotz, Karola

    2011-01-01

    Integrating the study of human diversity into the human evolutionary sciences requires substantial revision of traditional conceptions of a shared human nature. This process may be made more difficult by entrenched, ‘folkbiological’ modes of thought. Earlier work by the authors suggests that biologically naive subjects hold an implicit theory according to which some traits are expressions of an animal's inner nature while others are imposed by its environment. In this paper, we report further studies that extend and refine our account of this aspect of folkbiology. We examine biologically naive subjects' judgments about whether traits of an animal are ‘innate’, ‘in its DNA’ or ‘part of its nature’. Subjects do not understand these three descriptions to be equivalent. Both innate and in its DNA have the connotation that the trait is species-typical. This poses an obstacle to the assimilation of the biology of polymorphic and plastic traits by biologically naive audiences. Researchers themselves may not be immune to the continuing pull of folkbiological modes of thought. PMID:21199848

  13. The natural flow wing-design concept

    NASA Technical Reports Server (NTRS)

    Wood, Richard M.; Bauer, Steven X. S.

    1992-01-01

    A wing-design study was conducted on a 65 degree swept leading-edge delta wing in which the wing geometry was modified to take advantage of the naturally occurring flow that forms over a slender wing in a supersonic flow field. Three-dimensional nonlinear analysis methods were used in the study which was divided into three parts: preliminary design, initial design, and final design. In the preliminary design, the wing planform, the design conditions, and the near-conical wing-design concept were derived, and a baseline standard wing (conventional airfoil distribution) and a baseline near-conical wing were chosen. During the initial analysis, a full-potential flow solver was employed to determine the aerodynamic characteristics of the baseline standard delta wing and to investigate modifications to the airfoil thickness, leading-edge radius, airfoil maximum-thickness position, and wing upper to lower surface asymmetry on the baseline near-conical wing. The final design employed an Euler solver to analyze the best wing configurations found in the initial design and to extend the study of wing asymmetry to develop a more refined wing. Benefits resulting from each modification are discussed, and a final 'natural flow' wing geometry was designed that provides an improvement in aerodynamic performance compared with that of a baseline conventional uncambered wing, linear-theory cambered wing, and near-conical wing.

  14. Natural optical design concepts for highly miniaturized camera systems

    NASA Astrophysics Data System (ADS)

    Voelkel, Reinhard

    1999-08-01

    Microcameras for computers, mobile phones, watches, security system and credit cards is a very promising future market. Semiconductor industry is now able to integrate light reception, signal amplification and processing in a low- power-consuming microchip of a few mm2 size. Active pixel sensors supply each pixel in an image sensor with an individually programmable functionality. Beside the electronic receptor chip, a highly miniaturized lens system is required. Compared to the progress in microelectronics, optics has not yet made a significant step. Today's microcamera lenses are usually a downscaled version of a classical lens system and rarely smaller than 3 mm X 3 mm X 3 mm. This lagging of optics is quite surprising. Biologists have systematically studied all types of natural eye sensors since the 18th Century. Mother Nature provides a variety of highly effective examples for miniaturized imaging system. Single-aperture systems are the appropriate solution if the size is a free design parameter. If the budget is tight and optics limited to size, nature prefers multiple-aperture systems, the so-called compound eyes. As compound eyes are limited in resolution and night view, a cluster of single-aperture eyes, as jumping spiders use, is probably a better solution. The recent development in micro- optics offers the chance to imitate such natural design concepts. We have investigated miniaturized imaging systems based on microlens array and natural optical design concepts. Practical limitations for system design, packaging and assembling are given. Examples for micro-optical components and imaging systems are presented.

  15. Marine geodesy - Problem areas and solution concepts

    NASA Technical Reports Server (NTRS)

    Saxena, N.

    1974-01-01

    This paper deals with a conceptional geodetic approach to solve various oceanic problems, such as submersible navigation under iced seas, demarcation/determination of boundaries in open ocean, resolving sea-level slope discrepancy, improving tsunami warning system, ecology, etc., etc. The required instrumentation is not described here. The achieved as well as desired positional accuracy estimates in open ocean for various tasks are also given.

  16. Naturally selecting solutions: the use of genetic algorithms in bioinformatics.

    PubMed

    Manning, Timmy; Sleator, Roy D; Walsh, Paul

    2013-01-01

    For decades, computer scientists have looked to nature for biologically inspired solutions to computational problems; ranging from robotic control to scheduling optimization. Paradoxically, as we move deeper into the post-genomics era, the reverse is occurring, as biologists and bioinformaticians look to computational techniques, to solve a variety of biological problems. One of the most common biologically inspired techniques are genetic algorithms (GAs), which take the Darwinian concept of natural selection as the driving force behind systems for solving real world problems, including those in the bioinformatics domain. Herein, we provide an overview of genetic algorithms and survey some of the most recent applications of this approach to bioinformatics based problems.

  17. Assessment of future natural gas vehicle concepts

    NASA Astrophysics Data System (ADS)

    Groten, B.; Arrigotti, S.

    1992-10-01

    The development of Natural Gas Vehicles is progressing rapidly under the stimulus of recent vehicle emission regulations. The development is following what can be viewed as a three step progression. In the first step, contemporary gasoline or diesel fueled automobiles are retrofitted with equipment enabling the vehicle to operate on either natural gas or standard liquid fuels. The second step is the development of vehicles which utilize traditional internal combustion engines that have been modified to operate exclusively on natural gas. These dedicated natural gas vehicles operate more efficiently and have lower emissions than the dual fueled vehicles. The third step is the redesigning, from the ground up, of a vehicle aimed at exploiting the advantages of natural gas as an automotive fuel while minimizing its disadvantages. The current report is aimed at identifying the R&D needs in various fuel storage and engine combinations which have potential for providing increased efficiency, reduced emissions, and reductions in vehicle weight and size. Fuel suppliers, automobile and engine manufacturers, many segments of the natural gas and other industries, and regulatory authorities will influence or be affected by the development of such a third generation vehicle, and it is recommended that GRI act to bring these groups together in the near future to begin, developing the focus on a 'designed-for-natural-gas' vehicle.

  18. Feature integration in natural language concepts.

    PubMed

    Hampton, James A; Storms, Gert; Simmons, Claire L; Heussen, Daniel

    2009-12-01

    Two experiments measured the joint influence of three key sets of semantic features on the frequency with which artifacts (Experiment 1) or plants and creatures (Experiment 2) were categorized in familiar categories. For artifacts, current function outweighed both originally intended function and current appearance. For biological kinds, appearance and behavior, an inner biological function, and appearance and behavior of offspring all had similarly strong effects on categorization. The data were analyzed to determine whether an independent cue model or an interactive model best accounted for how the effects of the three feature sets combined. Feature integration was found to be additive for artifacts but interactive for biological kinds. In keeping with this, membership in contrasting artifact categories tended to be superadditive, indicating overlapping categories, whereas for biological kinds, it was subadditive, indicating conceptual gaps between categories. It is argued that the results underline a key domain difference between artifact and biological concepts.

  19. Threshold concepts: implications for the management of natural resources

    USGS Publications Warehouse

    Guntenspergen, Glenn R.; Gross, John

    2014-01-01

    Threshold concepts can have broad relevance in natural resource management. However, the concept of ecological thresholds has not been widely incorporated or adopted in management goals. This largely stems from the uncertainty revolving around threshold levels and the post hoc analyses that have generally been used to identify them. Natural resource managers have a need for new tools and approaches that will help them assess the existence and detection of conditions that demand management actions. Recognition of additional threshold concepts include: utility thresholds (which are based on human values about ecological systems) and decision thresholds (which reflect management objectives and values and include ecological knowledge about a system) as well as ecological thresholds. All of these concepts provide a framework for considering the use of threshold concepts in natural resource decision making.

  20. The nature of dissection: Exploring student conceptions

    NASA Astrophysics Data System (ADS)

    York, Katharine

    The model of conceptual change in science describes the process of learning as a complete restructuring of knowledge, when learners discover or are shown more plausible, intelligent alternatives to existing conceptions. Emotions have been acknowledged as part of a learner's conceptual ecology, but the effects of emotions on learning have yet to be described. This research was conducted to examine the role that emotions have on learning for thirteen high school students, as they dissected cats in a Human Anatomy and Physiology class. The project also investigated whether a student's emotional reactions may be used to develop a sense of connectedness with the nonhuman world, which is defined as ecological literacy. This study utilized a grounded theory approach, in which student responses to interviews were the primary source of data. Interviews were transcribed, and responses were coded according to a constant comparative method of analysis. Responses were compared with the four conditions necessary for conceptual change to occur, and also to five principles of ecological literacy. Students who had negative reactions to dissection participated less in the activity, and demonstrated less conceptual change. Two female students showed the strongest emotional reactions to dissection, and also the lowest amount of conceptual change. One male student also had strong negative reactions to death, and showed no conceptual change. The dissection experiences of the students in this study did not generally reflect ecological principles. The two students whose emotional reactions to dissection were the most negative demonstrated the highest degree of ecological literacy. These results provide empirical evidence of the effects that emotions have on learning, and also supports the opinions of educators who do not favor dissection, because it does not teach students to respect all forms of life.

  1. Solution dynamics of synthetic and natural polyelectrolytes

    NASA Astrophysics Data System (ADS)

    Krause, Wendy E.

    Polyelectrolytes are abundant in nature and essential to life, and used extensively in industry. This work discussed two polyelectrolytes: sodium poly(2-acrylamido-2-methylpropanesulfonate) (NaPAMS), synthetic polyelectrolyte, and sodium hyaluronate (NaHA), a glycosaminoglycan. Rheological data of NaPAMS solutions of variable chain length and concentration were reported. A strong dependence of viscosity eta on chain length: eta ˜ M2.4 was found. The comparison of the rheological data with two proposed scaling theories (Dobrynin 1995, Witten 1987) forces the conclusion that neither theory is correct. A possible interpretation of the viscosity data falling between the predictions of the two scaling theories is that some chain rigidity may persist beyond the correlation length. A sample model for the conductivity of semidilute polyelectrolytes with no added salt was presented. The model correctly describes the logarithmic decrease of specific conductance observed for many polyelectrolytes at low concentration (below ca. 10-2M), and is in good agreement with data from NaPAMS solutions. NaHA in phosphate buffered saline behaves as a typical polyelectrolyte in the high-salt limit, as Newtonian viscosities are observed over a wide range of shear rates. There is no evidence of intermolecular hydrogen bonding causing gel formation in NaHA solutions without protein present. The viscosity of 3 mg/mL NaHA was measured in the presence of the selected anti-inflammatory agents. Of the seven additives investigated only (D)-penicillamine significantly altered the rheology of HA. (D)-Penicillamine dramatically reduced the viscosity of HA, probably by disrupting intramolecular hydrogen bonding. The plasma proteins albumin and gamma-globulins bind to HA in solution to form a weak reversible gel. The rheology and osmotic pressure of the simple model for synovial fluid, consisting of 3mg/mL NaHA, 11 mg/mL albumin, and 7 mg/mL gamma-globulins in phosphate buffered saline, were studied

  2. Wallpaper concept solution fabrication experiences in FGD systems

    SciTech Connect

    Agarwal, D.C.; Flasche, L.H.

    1987-01-01

    In the last few years, a concentrated research effort has led to a better understanding of the corrosion problems in flue gas desulfurization (FGD) systems of coal fired power plants. At first look, operation of a typical limestone FGD system appears very simple, hence the first generation scrubbers of early to mid 70's were designers inspiration. However, the designers inspiration soon turned into a utility's nightmare due to failures of metals and non-metals, both failing in a an embarrassingly short time. A solution was needed which had to be reliable, simple, and cost effective. This objective was met via the application of wallpaper concept, which now has been very well accepted in the industry and is becoming increasingly more popular due to the many successful case histories. This paper describes the wallpaper concept solution, the fabrication techniques, the experiences at certain utilities, the precautions which need to be followed, the associated economics, and some case histories.

  3. Solution Concepts for Distributed Decision-Making without Coordination

    NASA Technical Reports Server (NTRS)

    Beling, Peter A.; Patek, Stephen D.

    2005-01-01

    Consider a single-stage problem in which we have a group N agents who are attempting to minimize the expected cost of their joint actions, without the benefit of communication or a pre-established protocol but with complete knowledge of the expected cost of any joint set of actions for the group. We call this situation a static coordination problem. The central issue in defining an appropriate solution concept for static coordination problems is considering how to deal with the fact that if the agents axe faced with a set of multiple (mixed) strategies that are equally attractive in terms of cost, a failure of coordination may lead to an expected cost value that is worse than that of any of the strategies in the set. In this proposal, we describe the notion of a general coordination problem, describe initial efforts at developing a solution concept for static coordination problems, and then outline a research agenda that centers on activities that will be basis for obtaining a complete understanding of solutions to static coordination problems.

  4. Concepts and implementations of natural language query systems

    NASA Technical Reports Server (NTRS)

    Dominick, Wayne D. (Editor); Liu, I-Hsiung

    1984-01-01

    The currently developed user language interfaces of information systems are generally intended for serious users. These interfaces commonly ignore potentially the largest user group, i.e., casual users. This project discusses the concepts and implementations of a natural query language system which satisfy the nature and information needs of casual users by allowing them to communicate with the system in the form of their native (natural) language. In addition, a framework for the development of such an interface is also introduced for the MADAM (Multics Approach to Data Access and Management) system at the University of Southwestern Louisiana.

  5. Green Extraction of Natural Products: Concept and Principles

    PubMed Central

    Chemat, Farid; Vian, Maryline Abert; Cravotto, Giancarlo

    2012-01-01

    The design of green and sustainable extraction methods of natural products is currently a hot research topic in the multidisciplinary area of applied chemistry, biology and technology. Herein we aimed to introduce the six principles of green-extraction, describing a multifaceted strategy to apply this concept at research and industrial level. The mainstay of this working protocol are new and innovative technologies, process intensification, agro-solvents and energy saving. The concept, principles and examples of green extraction here discussed, offer an updated glimpse of the huge technological effort that is being made and the diverse applications that are being developed. PMID:22942724

  6. "The City Snuffs out Nature": Young People's Conceptions of and Relationship with Nature

    ERIC Educational Resources Information Center

    Pointon, Pam

    2014-01-01

    This paper reports a study of 384 13-14-year olds' written responses to open-ended questions about their understanding of and relationship with "nature." Using constant comparative method the responses were coded, categorised and themed. Most students held scientific conceptions of nature (excluding humans) and a utilitarian relationship…

  7. The Concept of Ecologically Oriented Progress and Natural Resource Preservation

    NASA Astrophysics Data System (ADS)

    Gasanov, M. A.; Kolotov, K. A.; Demidenko, K. A.; Podgornaya, E. A.; Kadnikova, O. V.

    2017-01-01

    The most important issue of scientific and technological progress is considering the environment challenges of industrial development. It means that the progress must be ecologically oriented and environmentally friendly. The most adequate concept for the approach to the issue of “man - society - nature” relations is the ontology of the noosphere - the idea of a common space for human beings and nature. It presents an ideal example of an optimistic attitude towards the coordination between accelerating the scientific and technological development and natural resource saving. However, to maintain the balance between human needs and environmental processes determined by this concept, it is essential to include the lean production training into technological development of society.

  8. A Concept-Centric Framework for Building Natural Language Interfaces

    NASA Astrophysics Data System (ADS)

    Funakoshi, Kotaro; Nakano, Mikio; Hasegawa, Yuji; Tsujino, Hiroshi

    Natural language interfaces are expected to come into practical use in many situations. It is, however, not practical to expect to achieve a universal interface because language use is so diverse. To that end, not only advancements in speech and language technologies but also well-designed development frameworks are required so that developers can build domain-specific interfaces rapidly and easily. This paper proposes KNOLU, a framework for building natural language interfaces of a broad range of applications. Developers using this framework can easily build an interface capable of understanding subsets of natural language expressions just by providing an ontology (a concept hierarchy with semantic frames and a lexicon), an onomasticon (a set of instances and their names) and API functions that provide procedural knowledge required to connect the interface to a target application. To develop an interface using KNOLU, first developers define a concept hierarchy for a target domain. Then they provide other declarative and procedural knowledge components with these knowledge components asscicated to the hierarchy. This developmental flow affords an unobstructed view both for development and maintanance. KNOLU uses an existing general-purpose parser and requires neither grammar rules nor expression patterns. It does not require rules to generate semantic interpretations from parsing results, either. Therefore, developers can build an interface without deep knowledge and experience of natural language processing. We applied KNOLU to two applications and confirmed the effectiveness.

  9. The concept of nature in Islamic science teaching

    NASA Astrophysics Data System (ADS)

    Zarman, Wendi

    2016-02-01

    Science teaching is basically value laden activities. One of the values tells that science is not related to any religion. This secular value is reflected to science teaching in many places, including religious country like Indonesia. However, we argue that in Indonesia science teaching should not be secular as in the Western country since one of the basic aim of National Education according to the Indonesian constitution Undang-Undang Dasar 1945, is to inculcate faith and god-fearing to One God Almighty. As we know, Indonesia is a Moslem country and has many Islamic schools in it too. Thus, it is important to design a science teaching framework base on Islamic teaching to fulfill the basic aim of National Education This paper discusses concept of nature, the key term in science, based on Islamic view that may used as a framework to develop Islamic science teaching. In Islam, science has a strong relation to religion since nature reflects the existence of the Creator. This concept is derived from the analysis of several verses from Qur'an as the main source of Islamic teaching. There are several principle can be derived from this analysis. Firstly, visible world is not the only world, but there is also the unseen world. Secondly, the nature is not merely matter that doesn't have any sacred value, but it is the indication or symbol of God existence and His Nature. Thirdly, The Qur'an and the nature are both Books of Allah that contain messages of Him, so they are complementary to each other

  10. Undergraduate Students' Conceptions of Natural and Anthropogenic Climate Change

    NASA Astrophysics Data System (ADS)

    Trenbath, K. L.

    2011-12-01

    constructed definition removes human-causes from association with the word "climate change", which may influence their climate change understanding. Of the two higher achieving students, one emphasized anthropogenic climate change at the beginning of the semester, but later focused on natural climate change during his interviews. The other high achieving student included tangential environmental topics in her descriptions of climate change throughout the entire semester, thus conflating climate change's definition. These alternative definitions of climate change indicate that the learners constructed hybrid conceptions in order to incorporate class content with their prior ideas. These hybrid conceptions indicate that the students' understandings lie somewhere between misconceptions and conceptual change. Since the students demonstrated these hybrid conceptions at the end of class, perhaps more time is needed for the students to process the information. These case studies identify the gaps the professor should address for conceptual change to fully occur.

  11. What's Natural about Nature? Deceptive Concepts in Socio-Scientific Decision-Making

    ERIC Educational Resources Information Center

    Lindahl, Mats Gunnar; Linder, Cedric

    2015-01-01

    The conflicts between nature and nurture are brought to the fore and challenges socio-scientific decision-making in science education. The multitude of meanings of these concepts and their roles in societal discourses can impede students' development of understanding for different perspectives, e.g. on gene technology. This study problematizes…

  12. Action being character: a promising perspective on the solution concept of game theory.

    PubMed

    Deng, Kuiying; Chu, Tianguang

    2011-05-09

    The inconsistency of predictions from solution concepts of conventional game theory with experimental observations is an enduring question. These solution concepts are based on the canonical rationality assumption that people are exclusively self-regarding utility maximizers. In this article, we think this assumption is problematic and, instead, assume that rational economic agents act as if they were maximizing their implicit utilities, which turns out to be a natural extension of the canonical rationality assumption. Implicit utility is defined by a player's character to reflect his personal weighting between cooperative, individualistic, and competitive social value orientations. The player who actually faces an implicit game chooses his strategy based on the common belief about the character distribution for a general player and the self-estimation of his own character, and he is not concerned about which strategies other players will choose and will never feel regret about his decision. It is shown by solving five paradigmatic games, the Dictator game, the Ultimatum game, the Prisoner's Dilemma game, the Public Goods game, and the Battle of the Sexes game, that the framework of implicit game and its corresponding solution concept, implicit equilibrium, based on this alternative assumption have potential for better explaining people's actual behaviors in social decision making situations.

  13. Quantifying nature: ideological representations in the concept of diversity.

    PubMed

    Nikisianis, Nikos; Stamou, George P

    2011-01-01

    The conflicts around the scientific status of the concept of diversity are considered here as symptoms of hidden, socially originated, ideological representations inherent in the theoretical context of western ecology. Species diversity was coined in the 1940s, as a constant in the statistical models that described the distribution of individuals into different species and, therefore, as the expression of all the parameters that determine ecologically this distribution. The assumption of such a regular distribution is attributed to the influence of organicism and the correlated presuppositions of harmony and homeostasis. Nevertheless, as species diversity was the only unknown parameter in these models, it reversed the direction of the functions and established itself as the main variable under question. After the 1950s, the concept of species diversity was empowered by the strong impact of cybernetics and systems theories; in this context, diversity was considered as a self-regulating mechanism that assures overall stability. Diversity emerges as a natural and one-dimensional measure of community complexity, maturity, and stability. In the perspective of the arising ecological crisis, diversity--because of its property to compare and evaluate--arises as the nodal point of the new scientific/ideological fields of nature conservation and ecosystem management.

  14. Monitoring the Impact of Solution Concepts within a Given Problematic

    NASA Astrophysics Data System (ADS)

    Cavallucci, Denis; Rousselot, François; Zanni, Cecilia

    It is acknowledged that one of the most critical issues facing today’s organizations concerns the substantial leaps required to methodologically structure innovation. Among other published work, some suggest that a complete rethinking of current practices is required. In this article, we propose a methodology aiming at providing controlled R&D choices based on a monitoring of the impact Solution Concepts provoke on a problematic situation. Initially this problematic situation is modeled in a graph form, namely a Problem Graph. It has the objective to assists R&D managers when choosing which activities to support and bring them concrete arguments to defend their choices. We postulate that by improving the robustness of such approaches we help deciders to switch from intuitive decisions (mostly built upon their past experiences, fear regarding risks, and awareness of the company’s level of acceptance of novelties) to thoroughly constructed inventive problem solving strategies. Our approach will be discussed using a computer application that illustrates our hypothesis after being tested in several industrial applications.

  15. Implementation of Lamarckian concepts in a Genetic Algorithm for structure solution from powder diffraction data

    NASA Astrophysics Data System (ADS)

    Turner, Giles W.; Tedesco, Emilio; Harris, Kenneth D. M.; Johnston, Roy L.; Kariuki, Benson M.

    2000-04-01

    Previous implementations of Genetic Algorithms in direct-space strategies for structure solution from powder diffraction data have employed the operations of mating, mutation and natural selection, with the fitness of each structure based on comparison between calculated and experimental powder diffraction patterns (we define fitness as a function of weighted-profile R-factor Rwp). We report an extension to this method, in which each structure generated in the Genetic Algorithm is subjected to local minimization of Rwp with respect to structural variables. This approach represents an implementation of Lamarckian concepts of evolution, and is found to give significant improvements in efficiency and reliability.

  16. Natural Orifice Surgery: Transdouglas Surgery—a New Concept

    PubMed Central

    Stark, Michael

    2008-01-01

    Background: During the 20th century, laparoscopic procedures replaced most traditional abdominal operations and achieved high-quality standards. It seemed that the optimal surgical method had been achieved; however, a new concept, which might possibly become even safer and simpler is now being developed, the concept of Natural Orifice Surgery (NOS). The existing natural openings of the body started to be used for introduction of surgical instruments for diagnostic purposes and surgical procedures, avoiding penetrating the abdominal wall. Parallel to the American Natural Orifice Surgery Consortium for Assessment and Research (NOSCAR) group, is the New European Surgical Academy (NESA) established in Berlin on June 23, 2006. It is the first European-based NOS working group with participation of scientists and surgeons from different disciplines and countries. After the published experimental achievements had been presented and discussed, the working group decided to concentrate mainly on the transvaginal/transdouglas access in women. Database: A new surgical instrument, the Transdouglas Endoscopic Device (TED) has been designed. This is a flexible multichannel instrument enabling single-entry surgical, urological, and gynecological operations. TED respects the anatomy of the pelvis. To get to the upper abdomen, an S-shaped device was designed, bending first to the front, and then backwards. For the lower abdomen, the U-shaped mode of the instrument was designed. The wide diameter of the device (35 mm) and its multichannel design enables simultaneous use of different instruments, therefore avoiding hybrid procedures. Various surgical and gynecological procedures have been successfully simulated, and the manufacturing of the device is in progress. Preclinical studies will start soon. Conclusions: Transvaginal/transdouglas surgery is expected to be a valid alternative to traditional endoscopic procedures in women. It seems that NOS will create a spectrum of innovative

  17. Metabiotics: novel idea or natural development of probiotic conception

    PubMed Central

    Shenderov, Boris A.

    2013-01-01

    Traditionally, probiotics on the base of live microorganisms are considered to be both beneficial and safe. Unfortunately, their effects may have short-term success or are absent or uncertain. Some symbiotic (probiotic) microorganisms with known beneficial health affects may cause opportunistic infections, increase incidence of allergic sensitization and autoimmune disorders, produce microecological imbalance, modify gene expression, transfer antibiotic resistant and virulence genes, cause disorders in epigenome and genome integrity, induce chromosomal DNA damage, and activate signaling pathways associated with cancer and other chronic diseases. The commercially available probiotics should be considered as a first generation means of correcting microecological disorders. Further, their development will include the selection of natural metabiotics and/or working out the synthetic (or semi-synthetic) metabiotics that will be analogies or improved copies of natural bioactives, produced by symbiotic (probiotic) microorganisms. Metabiotics are the structural components of probiotic microorganisms and/or their metabolites and/or signaling molecules with a determined (known) chemical structure that can optimize host-specific physiological functions, regulator, metabolic and/or behavior reactions connected with the activity of host indigenous microbiota. Metabiotics have some advantages because of their exact chemical structure, well dosed, very safe and long shelf-life. Thus, now metabiotics should not consider myth; they are the result of the natural evolution of probiotic conception. PMID:23990841

  18. The Concept of Human Nature in Three Cultures: A Developmental Approach.

    ERIC Educational Resources Information Center

    Oerter, Rolf

    This study compares the concept of human nature in Germany, Java, and the United States. The study assumes cross-cultural similarities in the formal structure of the concept of human nature, while hypothesizing variation in content, for example, in the value systems. Four components of the concept of human nature were presented (personality…

  19. Nature is (a) mine: conceptions of nature in the Dutch ecogenomics community.

    PubMed

    Van der Hout, Sanne

    2014-12-01

    Every field of science, but especially biology, contains particular conceptions of nature. These conceptions are not merely epistemological or ontological, but also have normative dimensions; they provide an ethos, a framework for moral orientation. These normative dimensions, whilst often remaining 'hidden' and inarticulate, influence the way in which biologists practice their profession. In this paper, I explore what happens when different versions of these implicit normative frameworks collide. To do so, I will focus on a case study from the field of ecological genomics as it has evolved in one particular country, namely the Netherlands. During an important inaugural meeting, the director of one of the most sizeable Dutch ecogenomics centres gave a presentation in which he introduced the term 'nature mining'. Part of the audience immediately embraced the term, but others were very reluctant. This mixed response is generally explained as a culmination of growing tension about the future direction of the field: due to new funding demands, a shift had occurred from fundamental research to research more interested in 'valorisation'.In addition to this current interpretation, I will argue that the turmoil caused by the use of the term 'nature mining' also reveals a more fundamental difference between the various parties involved in the Dutch ecogenomics community. This term is part of a vocabulary that emphasises the beneficial 'goods' produced by nature. Whereas part of the audience saw no harm in this commodification of nature, others had difficulties with the reduction of nature to a reservoir to be exploited using the latest technologies. I will conclude by arguing that, although at present, the core of Dutch ecogenomics research reflects a more or less instrumental attitude towards nature, the field also harbours other interpretations of nature as a significant and meaningful order. For instance, ecogenomics might further develop the image of land as a

  20. Photodegradation of triazine herbicides in aqueous solutions and natural waters.

    PubMed

    Evgenidou, E; Fytianos, K

    2002-10-23

    The photodegradation of three triazines, atrazine, simazine, and prometryn, in aqueous solutions and natural waters using UV radiation (lambda > 290 nm) has been studied. Experimental results showed that the dark reactions were negligible. The rate of photodecomposition in aqueous solutions depends on the nature of the triazines and follows first-order kinetics. In the case of the use of hydrogen peroxide and UV radiation, a synergistic effect was observed. The number of photodegradation products detected, using FIA/MS and FIA/MS/MS techniques, suggests the existence of various degradation routes resulting in complex and interconnected pathways.

  1. The science, policy and practice of nature-based solutions: An interdisciplinary perspective.

    PubMed

    Nesshöver, Carsten; Assmuth, Timo; Irvine, Katherine N; Rusch, Graciela M; Waylen, Kerry A; Delbaere, Ben; Haase, Dagmar; Jones-Walters, Lawrence; Keune, Hans; Kovacs, Eszter; Krauze, Kinga; Külvik, Mart; Rey, Freddy; van Dijk, Jiska; Vistad, Odd Inge; Wilkinson, Mark E; Wittmer, Heidi

    2017-02-01

    In this paper, we reflect on the implications for science, policy and practice of the recently introduced concept of Nature-Based Solutions (NBS), with a focus on the European context. First, we analyse NBS in relation to similar concepts, and reflect on its relationship to sustainability as an overarching framework. From this, we derive a set of questions to be addressed and propose a general framework for how these might be addressed in NBS projects by funders, researchers, policy-makers and practitioners. We conclude that: To realise their full potential, NBS must be developed by including the experience of all relevant stakeholders such that 'solutions' contribute to achieving all dimensions of sustainability. As NBS are developed, we must also moderate the expectations placed on them since the precedent provided by other initiatives whose aim was to manage nature sustainably demonstrates that we should not expect NBS to be cheap and easy, at least not in the short-term.

  2. Teaching Concepts of Natural Sciences to Foreigners through Content-Based Instruction: The Adjunct Model

    ERIC Educational Resources Information Center

    Satilmis, Yilmaz; Yakup, Doganay; Selim, Guvercin; Aybarsha, Islam

    2015-01-01

    This study investigates three models of content-based instruction in teaching concepts and terms of natural sciences in order to increase the efficiency of teaching these kinds of concepts in realization and to prove that the content-based instruction is a teaching strategy that helps students understand concepts of natural sciences. Content-based…

  3. Reuse of spent natural gas liquid sweetening solutions

    SciTech Connect

    Hahn, W.J.; McKim, M.N.; Smith, L.S.

    1995-12-01

    Partially spent caustic solutions from natural gas liquids (NGL) sweetening processes can be used as reagent for sulfur dioxide (SO{sub 2}) scrubbing facilities, reducing the costs for purchasing scrubber reagent and eliminating the costs and liabilities associated with waste disposal. This paper discusses: (1) the characteristics of typical spent NGL sweetening solutions, (2) State and Federal regulations governing the disposal of these solutions as wastes, (3) the operational variables affecting reuse of these solutions in SO{sub 2} scrubbers, (4) field and laboratory analytical data from a pilot project conducted to evaluate the reuse of a partially spent NGL sweetening solution as SO{sub 2} scrubber reagent, and (5) economic data from the pilot project. For the pilot project, a partially spent caustic NGL sweetening solution was used in place of soda ash solution as reagent in a SO{sub 2} scrubber serving two steam generators burning sour gas. Emissions testing of the scrubber demonstrated that the solution provided effective removal of oxides of sulfur (SO{sub x}) in both gaseous and particulate phases to meet permitted limits. Data from the pilot project is used in the paper to: (1) quantify SO{sub 2} scrubber performance with partially spent caustic solutions in terms of SO{sub x} removal efficiency, (2) identify the necessary modifications in scrubber operation (reagent feed rate, scrubber liquor pH and specific gravity, blowdown rate) to achieve acceptable performance using partially spent caustic solutions, and (3) describe the effect that the use of partially spent caustic solutions has on physical and chemical properties of scrubber liquor.

  4. [Mouthwash solutions with microencapsuled natural extracts: Efficiency for dental plaque and gingivitis].

    PubMed

    Vervelle, A; Mouhyi, J; Del Corso, M; Hippolyte, M-P; Sammartino, G; Dohan Ehrenfest, D M

    2010-06-01

    Mouthwash solutions are mainly used for their antiseptic properties. They currently include synthetic agents (chlorhexidine, triclosan, etc.) or essential oils (especially Listerine). Many natural extracts may also be used. These associate both antiseptic effects and direct action on host response, due to their antioxidant, immunoregulatory, analgesic, buffering, or healing properties. The best known are avocado oil, manuka oil, propolis oil, grapefruit seed extract, pycnogenol, aloe vera, Q10 coenzyme, green tea, and megamin. The development of new technologies, such as microencapsulation (GingiNat concept), may allow an in situ slow release of active ingredients during several hours, and open new perspectives for mouthwash solutions.

  5. MODELLING OF AGRICHEMICALS IN ENVIRONMENTAL COMPARTMENTS - CONCEPTS, PROBLEMS, AND SOLUTIONS

    EPA Science Inventory

    The potential of plant protection chemicals to migrate away from application sites and expose non-target biota is of continuing interest and concern to regulatory specialists, ecotoxicologists, agriculturalists, and natural resource managers. Regulatory decisions can wait upon ne...

  6. Ammonia removal from leachate solution using natural Chinese clinoptilolite.

    PubMed

    Wang, Yuqiu; Liu, Shijun; Xu, Ze; Han, Tianwei; Chuan, Sun; Zhu, Tan

    2006-08-25

    This paper assesses the potential of natural Chinese clinoptilolite for ammonia removal from the leachate solution of sewage sludge. In batch study the effects of relevant parameters, such as contact time, initial ammonia concentration and particle size of clinoptilolite, were examined respectively. The results show that the data obtained from batch studies were fit to Langmuir and Freundlich isotherms and the Langmuir isotherms reflect more reasonable for ammonium ion uptake onto clinoptilolite; the clinoptilolite adsorption process has been proved effective, at laboratory scale, the maximum adsorption capacity of the clinoptilolite, for ammonium concentration ranging from 11.12 to 115.16 mg NH(4)-N L(-1) in leachate solution, was about 1.74 mg NH(4)-Ng(-1); the time to adsorption equilibrium was 2.5 h in leachate solution and 1.5 h more than for in NH(4)Cl synthetic solution; ammonium adsorption increased with decreasing clinoptilolite particle size; the ammonia removal capacity of clinoptilolite increased with increasing initial ammonia concentration. It is believed that as adsorption agent for NH(4)-N removal from sludge leachate, natural Chinese clinoptilolite can be feasible.

  7. The interstellar conundrum: a survey of concepts and proposed solutions.

    PubMed

    Gilster, Paul A

    2005-12-01

    Once considered intractable, the problem of interstellar flight is slowly yielding to analysis. Although manned missions to the stars are exceedingly improbable in this century, the possibility of interstellar robotic probes should not be ruled out. Recent laboratory work and theoretical analysis suggest several near-term technologies that could, given the development of an adequate space-based infrastructure, provide the needed propulsion. Laser-driven lightsails offer the key advantage of leaving the fuel behind, with the laser beam focused by a large Fresnel lens in the outer Solar System. Perhaps more efficient is the use of a particle beam to boost a spacecraft by interacting with its magnetic sail, the latter a system already under intense scrutiny. Variations on "pellet" propulsion using macroscopic objects continue to surface, their mass converted to energy as they arrive at the departing starship. Interstellar flight will be both difficult and expensive, although it can no longer be considered an impossibility. This paper examines the above concepts and relates them to older ideas, such as the Bussard ramjet, that are currently out of favor. The vibrancy of interstellar flight studies is its syncretism-it was through analysis of the drag problem in fusion ramjet designs that a practical means of decelerating an interstellar probe by deployment of a magnetic sail emerged. The intermingling of such ideas offers the hope of robust hybrid concepts that may make interstellar flight a reality.

  8. High School Biology Students' Transfer of the Concept of Natural Selection: A Mixed-Methods Approach

    ERIC Educational Resources Information Center

    Pugh, Kevin J.; Koskey, Kristin L. K.; Linnenbrink-Garcia, Lisa

    2014-01-01

    The concept of natural selection serves as a foundation for understanding diverse biological concepts and has broad applicability to other domains. However, we know little about students' abilities to transfer (i.e. apply to a new context or use generatively) this concept and the relation between students' conceptual understanding and transfer…

  9. ARPA-E: Creating Practical, Affordable Natural Gas Storage Solutions

    SciTech Connect

    Boysen, Dane; Loukus, Josh; Hansen, Rita

    2014-02-24

    Allowing people to refuel natural gas vehicles at home could revolutionize the way we power our cars and trucks. Currently, our nation faces two challenges in enabling natural gas for transportation. The first is improving the way gas tanks are built for natural gas vehicles; they need to be conformable, allowing them to fit tightly into the vehicle. The second challenge is improving the way those tanks are refueled while maintaining cost-effectiveness, safety, and reliability. This video highlights two ARPA-E project teams with innovative solutions to these challenges. REL is addressing the first challenge by developing a low-cost, conformable natural gas tank with an interconnected core structure. Oregon State University and OnBoard Dynamics are addressing the second challenge by developing a self-refueling natural gas vehicle that integrates a compressor into its engine-using one of the engine's cylinders to compress gas eliminates the need for an expensive at-home refueling system. These two distinct technologies from ARPA-E's MOVE program illustrate how the Agency takes a multi-pronged approach to problem solving and innovation.

  10. ARPA-E: Creating Practical, Affordable Natural Gas Storage Solutions

    ScienceCinema

    Boysen, Dane; Loukus, Josh; Hansen, Rita

    2016-07-12

    Allowing people to refuel natural gas vehicles at home could revolutionize the way we power our cars and trucks. Currently, our nation faces two challenges in enabling natural gas for transportation. The first is improving the way gas tanks are built for natural gas vehicles; they need to be conformable, allowing them to fit tightly into the vehicle. The second challenge is improving the way those tanks are refueled while maintaining cost-effectiveness, safety, and reliability. This video highlights two ARPA-E project teams with innovative solutions to these challenges. REL is addressing the first challenge by developing a low-cost, conformable natural gas tank with an interconnected core structure. Oregon State University and OnBoard Dynamics are addressing the second challenge by developing a self-refueling natural gas vehicle that integrates a compressor into its engine-using one of the engine's cylinders to compress gas eliminates the need for an expensive at-home refueling system. These two distinct technologies from ARPA-E's MOVE program illustrate how the Agency takes a multi-pronged approach to problem solving and innovation.

  11. Solution of naturally-ocurring glasses in the geological environment

    NASA Technical Reports Server (NTRS)

    Glass, B. P.

    1982-01-01

    As part of a study to investigate the feasibility of putting nuclear wastes in glass containers and burying them on land or dumping them in the ocean, the amount of solution experience by naturally occurring glasses from two land sites and thirty-four deep sea sites was studied. The glasses are microtektites from three strewn fields and from the Zhamanshin impact crater. The microtektites range in age from 0.7 to 35 m.y. and have a wide range in composition. The weight percent SiO2, for example, ranges from 44.8 to 81.7. Although several criteria for determining the amount of solution were considered, most of the conclusions are based on two criteria: (1) width of cracks, and (2) elevation of silica rich inclusions above the adjacent microtektite surface. All the measurements were made on scanning electron microscope photomicrographs of the microtektites.

  12. Design Conception of a Solution Ion Source Based Particle Accelerator

    NASA Astrophysics Data System (ADS)

    Ashis, Das

    2004-05-01

    Particle accelerators till date have been based on several ion source principles such as thermal ionization, stripping etc. Such methods of ion source enabling is very limited by high temperature of ionization required in cases of very heavy ions generation. Heavy ions speeding in accelerator may lead to experiments with such ions in both accelerators and colliders, that is believed capable of opening new regimes of particle accelerator studies that is very heavy very heavy collision. Literature indicate that many yet-unknown mysteries of atomic and subnuclear Physics, creation and fate of Universe, new element synthesis all lie in this regime of investigation. In this paper, I outline a simpler and less energetic manner of creating, particularly, speeding very heavy ions using a solution ion stripping source such as with liquid ammonia which has ability to dissolve many heavy metals in form of ammonia-metal ion clusters, that can be led to a specially designed accelerator chamber as detailed in the paper. It is surprising indeed why such easy road to ions source generation was not conceived by particle accelerator Physicists earlier.

  13. Australian Secondary School Students' Concepts Regarding the Nature of Science.

    ERIC Educational Resources Information Center

    Griffiths, Alan K.; Barman, Charles R.

    1993-01-01

    Describes a study in which secondary students (N=32) were interviewed to determine their understanding of the nature of scientific knowledge. Presents some of the strengths and weaknesses of these views and provides cross-cultural comparisons. (DDR)

  14. Photosensitized degradation of amoxicillin in natural organic matter isolate solutions.

    PubMed

    Xu, Haomin; Cooper, William J; Jung, Jinyoung; Song, Weihua

    2011-01-01

    Amoxicillin is a widely used antibiotic and has been detected in natural waters. Its environmental fate is in part determined by hydrolysis, and, direct and indirect photolysis. The hydrolysis rate in distilled water and water to which five different isolated of dissolved organic matter (DOM) was added, were evaluated. In the five different DOM solutions hydrolysis accounted for 5-18% loss of amoxicillin. Direct and indirect photolysis rates were determined using a solar simulator and it appeared that indirect photolysis was the dominant loss mechanism. Direct photolysis, in a solar simulator, accounted for 6-21% loss of amoxicillin in the simulated natural waters. The steady-state concentrations of singlet oxygen, (1)ΔO(2) (∼10(-13) M) and hydroxyl radical, •OH (∼10(-17) M) were obtained in aqueous solutions of five different dissolved organic matter samples using a solar simulator. The bimolecular reaction rate constant of (1)ΔO(2) with amoxicillin was measured in the different solutions, k(ΔO(2)) = 1.44 × 10(4) M(-1) s(-1). The sunlight mediated amoxicillin loss rate with (1)ΔO(2) (∼10(-9) s(-1)), and with •OH (∼10(-7) s(-1)), were also determined for the different samples of DOM. While (1)ΔO(2) only accounted for 0.03-0.08% of the total loss rate, the hydroxyl radical contributed 10-22%. It appears that the direct reaction of singlet and triplet excited state DOM ((3)DOM(∗)) with amoxicillin accounts for 48-74% of the loss of amoxicillin. Furthermore, the pseudo first-order photodegradation rate showed a positive correlation with the sorption of amoxicillin to DOM, which further supported the assumption that excited state DOM∗ plays a key role in the photochemical transformation of amoxicillin in natural waters. This is the first study to report the relative contribution of all five processes to the fate of amoxicillin in aqueous solution.

  15. Developing an instrument for assessing students' concepts of the nature of technology

    NASA Astrophysics Data System (ADS)

    Liou, Pey-Yan

    2015-05-01

    Background:The nature of technology has been rarely discussed despite the fact that technology plays an essential role in modern society. It is important to discuss students' concepts of the nature of technology, and further to advance their technological literacy and adaptation to modern society. There is a need to assess high school students' concepts of the nature of technology. Purpose:This study aims to engage in discourse on students' concepts of the nature of technology based on a proposed theoretical framework. Moreover, another goal is to develop an instrument for measuring students' concepts of the nature of technology. Sample:Four hundred and fifty-five high school students' perceptions of technology were qualitatively analyzed. Furthermore, 530 students' responses to a newly developed questionnaire were quantitatively analyzed in the final test. Design and method:First, content analysis was utilized to discuss and categorize students' statements regarding technology and its related issues. The Student Concepts of the Nature of Technology Questionnaire was developed based on the proposed theoretical framework and was supported by the students' qualitative data. Finally, exploratory factor analysis and reliability analysis were applied to determine the structure of the items and the internal consistency of each scale. Results:Through a process of instrument development, the Student Concepts of the Nature of Technology Questionnaire was shown to be a valid and reliable tool for measuring students' concepts of the nature of technology. This newly developed questionnaire is composed of 29 items in six scales, namely 'technology as artifacts,' 'technology as an innovation change,' 'the current role of technology in society,' 'technology as a double-edged sword,' 'technology as a science-based form,' and 'history of technology.' Conclusions:The Student Concepts of the Nature of Technology Questionnaire has been confirmed as a reasonably valid and reliable

  16. Fuels Containing Methane of Natural Gas in Solution

    NASA Technical Reports Server (NTRS)

    Sullivan, Thomas A.

    2004-01-01

    While exploring ways of producing better fuels for propulsion of a spacecraft on the Mars sample return mission, a researcher at Johnson Space Center (JSC) devised a way of blending fuel by combining methane or natural gas with a second fuel to produce a fuel that can be maintained in liquid form at ambient temperature and under moderate pressure. The use of such a blended fuel would be a departure for both spacecraft engines and terrestrial internal combustion engines. For spacecraft, it would enable reduction of weights on long flights. For the automotive industry on Earth, such a fuel could be easily distributed and could be a less expensive, more efficient, and cleaner-burning alternative to conventional fossil fuels. The concept of blending fuels is not new: for example, the production of gasoline includes the addition of liquid octane enhancers. For the future, it has been commonly suggested to substitute methane or compressed natural gas for octane-enhanced gasoline as a fuel for internal-combustion engines. Unfortunately, methane or natural gas must be stored either as a compressed gas (if kept at ambient temperature) or as a cryogenic liquid. The ranges of automobiles would be reduced from their present values because of limitations on the capacities for storage of these fuels. Moreover, technical challenges are posed by the need to develop equipment to handle these fuels and, especially, to fill tanks acceptably rapidly. The JSC alternative to provide a blended fuel that can be maintained in liquid form at moderate pressure at ambient temperature has not been previously tried. A blended automotive fuel according to this approach would be made by dissolving natural gas in gasoline. The autogenous pressure of this fuel would eliminate the need for a vehicle fuel pump, but a pressure and/or flow regulator would be needed to moderate the effects of temperature and to respond to changing engine power demands. Because the fuel would flash as it entered engine

  17. Turkish Pupils' Conceptions of the Particulate Nature of Matter

    ERIC Educational Resources Information Center

    Boz, Yezdan

    2006-01-01

    The purpose of this research study is to explore year 6, 8 & 11 (13, 15 and 17 years old respectively) Turkish pupils' views about the particulate nature of matter within the context of phase changes. About 300 pupils participated in the study. Questionnaires distributed to year 6, 8 and 11 pupils included 6-item open-ended questions about (a)…

  18. Natural resource valuation: A primer on concepts and techniques

    SciTech Connect

    Ulibarri, C.A.; Wellman, K.F.

    1997-07-01

    Natural resource valuation has always had a fundamental role in the practice of cost-benefit analysis of health, safety, and environmental issues. Today, this role is becoming all the more apparent in the conduct of natural resource damage assessments (NRDA) and cost-benefit analyses of environmental restoration (ER) and waste management (WM) activities. As such, environmental professionals are more interested in how natural resource values are affected by ER and WM activities. This professional interest extends to the use of NRDA values as measures of liability and legal causes of action under such environmental status as the Clean Water Act (CWA); the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA, as amended); and the Oil Pollution Act (OPA) of 1990. Also, environmental professionals are paying closer attention to NRDA values in cost-benefit analyses of risk and pollution-abatement standards, and in meeting environmental and safety standards - for achievable (ALARA). This handbook reviews natural resource valuation techniques that may be applied to resources at DOE sites within the foregoing contexts.

  19. Applying the dark diversity concept to nature conservation.

    PubMed

    Lewis, Rob J; de Bello, Francesco; Bennett, Jonathan A; Fibich, Pavel; Finerty, Genevieve E; Götzenberger, Lars; Hiiesalu, Inga; Kasari, Liis; Lepš, Jan; Májeková, Maria; Mudrák, Ondřej; Riibak, Kersti; Ronk, Argo; Rychtecká, Terezie; Vitová, Alena; Pärtel, Meelis

    2017-02-01

    Linking diversity to biological processes is central for developing informed and effective conservation decisions. Unfortunately, observable patterns provide only a proportion of the information necessary for fully understanding the mechanisms and processes acting on a particular population or community. We suggest conservation managers use the often overlooked information relative to species absences and pay particular attention to dark diversity (i.e., a set of species that are absent from a site but that could disperse to and establish there, in other words, the absent portion of a habitat-specific species pool). Together with existing ecological metrics, concepts, and conservation tools, dark diversity can be used to complement and further develop conservation prioritization and management decisions through an understanding of biodiversity relativized by its potential (i.e., its species pool). Furthermore, through a detailed understanding of the population, community, and functional dark diversity, the restoration potential of degraded habitats can be more rigorously assessed and so to the likelihood of successful species invasions. We suggest the application of the dark diversity concept is currently an underappreciated source of information that is valuable for conservation applications ranging from macroscale conservation prioritization to more locally scaled restoration ecology and the management of invasive species.

  20. The Nature of Science in Science Curricula: Methods and Concepts of Analysis

    ERIC Educational Resources Information Center

    Ferreira, Sílvia; Morais, Ana M.

    2013-01-01

    The article shows methods and concepts of analysis of the nature of science in science curricula through an exemplary study made in Portugal. The study analyses the extent to which the message transmitted by the Natural Science curriculum for Portuguese middle school considers the nature of science. It is epistemologically and sociologically…

  1. Natural resource validation: A primer on concepts and techniques

    SciTech Connect

    Ulibarri, C.A.; Wellman, K.F.

    1997-07-01

    Natural resource valuation has always had a fundamental role in the practice of cost-benefit analysis of health, safety, and environmental issues. The authors provide an objective overview of resource valuation techniques and describe their potential role in environmental restoration/waste management (ER/WM) activities at federal facilities. This handbook considers five general classes of valuation techniques: (1) market-based techniques, which rely on historical information on market prices and transactions to determine resource values; (2) nonmarket techniques that rely on indirect estimates of resource values; (3) nonmarket techniques that are based on direct estimates of resource values; (4) cross-cutting valuation techniques, which combine elements of one or more of these methods; and (5) ecological valuation techniques used in the emerging field of ecological economics. The various valuation techniques under consideration are described by highlighting their applicability in environmental management and regulation. The handbook also addresses key unresolved issues in the application of valuation techniques generally, including discounting future values, incorporating environmental equity concerns, and concerns over the uncertainties in the measurement of natural resource values and environmental risk.

  2. Technology Knowledge: High School Science Teachers' Conceptions of the Nature of Technology

    ERIC Educational Resources Information Center

    Waight, Noemi

    2014-01-01

    In-depth interviews guided by video elicitations examined 30 high school science teachers' conceptions of technology and by extension how these conceptions reflected dimensions of nature of technology. Altogether, 64% of the teachers characterized their schools and departments as aggressive-moderate adopters with generous access and support…

  3. Different Conceptions of the Nature of Science among Preservice Elementary Teachers of Two Countries

    ERIC Educational Resources Information Center

    Park, Do-Yong; Lee, Yong Bok

    2009-01-01

    This study examined the differences of the nature of science (NOS) conceptions portrayed by preservice teachers in Korea (N = 42) and the United States (N = 50). We conducted a survey of preservice elementary science teachers' NOS conceptions followed by interviews in both countries to further investigate their viewpoints. The NOS domains of this…

  4. Investigating the Relationship between Teachers' Nature of Science Conceptions and Their Practice of Inquiry Science

    ERIC Educational Resources Information Center

    Atar, Hakan Yavuz; Gallard, Alejandro

    2011-01-01

    In addition to recommending inquiry as the primary approach to teaching science, developers of recent reform efforts in science education have also strongly suggested that teachers develop a sound understanding of the nature of science. Most studies on teachers' NOS conceptions and inquiry beliefs investigated these concepts of teachers' NOS…

  5. Categorization of novel stimuli in well-known natural concepts: a case study.

    PubMed

    Storms, G; De Boeck, P; Ruts, W

    2001-06-01

    In this study, we investigated to what extent exemplar-based and prototype predictors can be applied to predicting categorization in natural language concepts. Participants categorized novel tropical foods into two well-known natural language concepts: fruits and vegetables. The results indicate that both the prototype predictors and the exemplar predictors contribute significantly in accounting for the categorization choices but that the contribution of the prototype predictor comes from just a limited number of features.

  6. Registered nurses' constructed meaning of concepts of solution and their use in clinical practice

    NASA Astrophysics Data System (ADS)

    Wilkes, Lesley M.; Batts, Judith E.

    1991-12-01

    Since the introduction of nursing into tertiary institutions in Australia in 1975, there has been increasing interest in the teaching of physical science to nurses. Various courses in physical science for nurse students have been developed. They vary in length and content but there is agreement that concepts taught should be closely related to nursing applications. The choice of relevant concepts tends to be made by individual curriculum developers. This paper reports an examination of the use of physical science concepts and their relevance from the perspective of registered nurses practising in general ward areas. Inherent in this study is the premise that for registered nurses to have ideas of the physical science underlying their practice they must have constructed meaning first for these concepts. Specific chemical concepts related to solutions are discussed in these terms.

  7. On the Concept of Information and Its Role in Nature

    NASA Astrophysics Data System (ADS)

    Roederer, Juan G.

    2003-03-01

    In this article we address some fundamental questions concerning information: Can the existing laws of physics adequately deal with the most striking property of information, namely to cause specific changes in the structure and energy flows of a complex system, without the information in itself representing fields, forces or energy in any of their characteristic forms? Or is information irreducible to the laws of physics and chemistry? Are information and complexity related concepts? Does the Universe, in its evolution, constantly generate new information? Or are information and information-processing exclusive attributes of living systems, related to the very definition of life? If that were the case, what happens with the physical meanings of entropy in statistical mechanics or wave function in quantum mechanics? How many distinct classes of information and information processing do exist in the biological world? How does information appear in Darwinian evolution? Does the human brain have unique properties or capabilities in terms of information processing? In what ways does information processing bring about human self-consciousness? We shall introduce the meaning of "information" in a way that is detached from human technological systems and related algorithms and semantics, and that is not based on any mathematical formula. To accomplish this we turn to the concept of interaction as the basic departing point, and identify two fundamentally different classes, with information and information-processing appearing as the key discriminator: force-field driven interactions between elementary particles and ensembles of particles in the macroscopic physical domain, and information-based interactions between certain kinds of complex systems that form the biological domain. We shall show that in an abiotic world, information plays no role; physical interactions just happen, they are driven by energy exchange between the interacting parts and do not require any

  8. Zeta potential of artificial and natural calcite in aqueous solution.

    PubMed

    Al Mahrouqi, Dawoud; Vinogradov, Jan; Jackson, Matthew D

    2017-02-01

    Despite the broad range of interest and applications, controls on calcite surface charge in aqueous solution, especially at conditions relevant to natural systems, remain poorly understood. The primary data source to understand calcite surface charge comprises measurements of zeta potential. Here we collate and review previous measurements of zeta potential on natural and artificial calcite and carbonate as a resource for future studies, compare and contrast the results of these studies to determine key controls on zeta potential and where uncertainties remain, and report new measurements of zeta potential relevant to natural subsurface systems. The results show that the potential determining ions (PDIs) for the carbonate mineral surface are the lattice ions Ca(2+), Mg(2+) and CO3(2-). The zeta potential is controlled by the concentration-dependent adsorption of these ions within the Stern layer, primarily at the Outer Helmholtz Plane (OHP). Given this, the Iso-Electric Point (IEP) at which the zeta potential is zero should be expressed as pCa (or pMg). It should not be reported as pH, similar to most metal oxides. The pH does not directly control the zeta potential. Varying the pH whilst holding pCa constant yields constant zeta potential. The pH affects the zeta potential only by moderating the equilibrium pCa for a given CO2 partial pressure (pCO2). Experimental studies that appear to yield a systematic relationship between pH and zeta potential are most likely observing the relationship between pCa and zeta potential, with pCa responding to the change in pH. New data presented here show a consistent linear relationship between equilibrium pH and equilibrium pCa or pMg irrespective of sample used or solution ionic strength. The surface charge of calcite is weakly dependent on pH, through protonation and deprotonation reactions that occur within a hydrolysis layer immediately adjacent to the mineral surface. The Point of Zero Charge (PZC) at which the surface

  9. Multiple Solutions Approach (MSA): Conceptions and Practices of Primary School Teachers in Ghana

    ERIC Educational Resources Information Center

    Nabie, Michael Johnson; Raheem, Kolawole; Agbemaka, John Bijou; Sabtiwu, Rufai

    2016-01-01

    The study explored the curriculum guidelines and primary school teachers' conceptions and practices of the Multiple Solutions Approach (MSA) in teaching mathematics using basic qualitative research design. Informal conversation interviews (ICIs), observations, video and document analyses were used to collect data. Participants included a purposive…

  10. Investigating the Effectiveness of an Analogy Activity in Improving Students' Conceptual Change for Solution Chemistry Concepts

    ERIC Educational Resources Information Center

    Calik, Muammer; Ayas, Alipasa; Coll, Richard K.

    2009-01-01

    This paper reports on an investigation on the use of an analogy activity and seeks to provide evidence of whether the activity enables students to change alternative conceptions towards views more in accord with scientific views for aspects of solution chemistry. We were also interested in how robust any change was and whether these changes in…

  11. Developing an Instrument for Assessing Students' Concepts of the Nature of Technology

    ERIC Educational Resources Information Center

    Liou, Pey-Yan

    2015-01-01

    Background: The nature of technology has been rarely discussed despite the fact that technology plays an essential role in modern society. It is important to discuss students' concepts of the nature of technology, and further to advance their technological literacy and adaptation to modern society. There is a need to assess high school students'…

  12. A Study of Taiwanese Children's Conceptions of and Relation to Nature: Curricular and Policy Implications

    ERIC Educational Resources Information Center

    Dai, Amy Hsin-I

    2011-01-01

    The present study investigated children's conceptions of and relations to nature. Understanding the factors that influence them was the goal. The study used the Contextual Model of Learning as the theoretical framework to structure the research questions and data analysis to understand children's nature learning in the personal, sociocultural, and…

  13. Science Teachers' Conceptions of Nature of Science: The Case of Bangladesh

    ERIC Educational Resources Information Center

    Sarkar, Md. Mahbub Alam; Gomes, Jui Judith

    2010-01-01

    This study explored Bangladeshi science teachers' conceptions of nature of science (NOS) with a particular focus on the nature of (a) scientific knowledge, (b) scientific inquiry and (c) scientific enterprise. The tentative, inferential, subjective and creative NOS, in addition to the myths of the scientific method and experimentation, the nature…

  14. Conceptions of the Nature of Science--Are They General or Context Specific?

    ERIC Educational Resources Information Center

    Urhahne, Detlef; Kremer, Kerstin; Mayer, Juergen

    2011-01-01

    The study investigates the relationship between general and context-specific conceptions of the nature of science (NOS). The categorization scheme by Osborne et al. (J Res Sci Teach 40:692-720, "2003") served as the theoretical framework of the study. In the category "nature of scientific knowledge", the certainty, development, simplicity,…

  15. Segregation of solutes and gases in experimental freezing of dilute solutions: implications for natural glacial systems

    NASA Astrophysics Data System (ADS)

    Killawee, J. A.; Fairchild, I. J.; Tison, J.-L.; Janssens, L.; Lorrain, R.

    1998-12-01

    Low ionic strength waters containing significant calcium and bicarbonate are common in nature, but little literature exists on their behaviour during freezing. Modelling indicates that freezing-induced concentration of solutes (in a closed-system) would lead to progressive increase in calcite saturation index, despite rising partial pressure of CO 2 (PCO 2), but the consequences of CaCO 3 precipitation for the distribution of matter between solid, liquid, and gas phases required experimental investigation. We studied the effects of variations in the rate of advance of an ice-water interface and in the initial degree of saturation for calcite on the behaviour of the system. Downward growth of ice in a 24-cm diameter cylindrical vessel was achieved at a constant linear rate of 3 or 8 mm/h by the progressive cooling of an overlying alcohol reservoir, and the expansion of volume accommodated by regular water sampling through side ports, together with a small expansion chamber. Initial air-saturated solutions (initial PCO 2 in the range 10 -3 to 10 -3.2) were prepared to reflect a range from strongly undersaturated to supersaturated for calcite. Comparative blank experiments were run using deionized water. Ice growth led to enrichment in solutes at the ice-water interface and the creation of a diffusive boundary layer, calculated to be 0.6 mm thick, truncated below by convecting fluid. The first-formed ice (stage 1), was relatively solute-rich because of initial rapid ice nucleation. Where solutions were not strongly supersaturated for calcite this was followed by formation of a solute-poor (stage 2) ice. Ice-interface water segregation coefficients of stage 2 ice were calculated to be 0.0004-0.003 for various solute ions. The relative magnitude of segregation coefficients (Mg 2+ > Ca 2+ > Sr 2+) is attributed to interstitial incorporation (coupled with HCO 3-) in the ice lattice, and controlled by ion size. Air bubbles nucleated once nitrogen supersaturation had

  16. The effect of teachers' language on students' conceptions of the nature of science

    NASA Astrophysics Data System (ADS)

    Zeidler, Dana L.; Lederman, Norman G.

    Conveying an adequate conception of the nature of science to students is implicit in the border context of what has come to be known as scientific literacy. However, it has previously been demonstrated that possession of valid conceptions of the nature of science does not necessarily result in the performance of those teaching behaviors that are related to improved student conceptions. The present study examines the possibility that the language teachers use to communicate science content may provide the context (Realist or Instrumentalist orientations) in which students come to formulate a world view of science. Eighteen high school biology teachers and one randomly selected class from each of their sections (n = 409 students) were administered pre- and posttests at the beginning and end of the fall term using the Nature of Scientific Knowledge Scale (NSKS). Composite scores of the student changes on the Testable, Developmental, and Creative subscales were used to compare those six classes that exhibited the greatest change with those six classes that had the least change on the NSKS. Intensive qualitative observations of each teacher were also conducted over the fall semester, resulting in complete transcripts of teacher-student interactions. Qualitative comparisons of classes with respect to six variables related to Realist and Instrumentalist conceptions of the nature of science were conducted. TEACHERS' ordinary language in the presentation of subject matter was found to have significant impact on students' conceptions of the nature of science. These variables represented different contexts (Realist-Instrumental) teachers used to express themselves, scientific information, and concepts. Determining the extent to which TEACHERS' language has an impact on changes in students' conception of the nature of science has direct bearing on all preservice and inservice science teacher education programs.

  17. Natural conception in HIV-serodiscordant couples with the infected partner in suppressive antiretroviral therapy

    PubMed Central

    Del Romero, Jorge; Baza, María Begoña; Río, Isabel; Jerónimo, Adrián; Vera, Mar; Hernando, Victoria; Rodríguez, Carmen; Castilla, Jesús

    2016-01-01

    Abstract The potential of antiretroviral treatment (ART) to prevent the sexual transmission of HIV has increased the number of serodiscordant couples who are considering natural conception. We aim to describe the results of a protocol for reproductive counseling aimed at HIV serodiscordant couples who desire natural conception, in which the infected partner, the index case, is receiving suppressive antiretroviral treatment. A prospective cohort included all HIV serodiscordant couples attended a counseling program in the period 2002 to 2013 who opted for natural conception and met the following criteria: index case on ART with persistent plasma viral suppression for at least the previous 6 months, ART compliance over 95%, preserved immune status, undetectable HIV viral and proviral load in semen in male index cases, and absence of genitourinary infections and fertility problems in both members of the couple. Of the 161 HIV serodiscordant couples included, 133 with male index cases, 66% achieved at least 1 pregnancy, 18% a second one, and 5% a third pregnancy. A total of 144 natural pregnancies occurred and 107 babies were born. The pregnancy rate was 1.9 for each 100 acts of vaginal intercourse, and the mean time to conception was 6.1 months, both independently of the sex of the index case. No case of sexual or vertical HIV transmission occurred. In the absence of fertility problems and under controlled conditions, natural conception might be a safe and effective reproductive method for those HIV serodiscordant couples who choose this reproductive option. PMID:27472733

  18. Natural Conception May Be an Acceptable Option in HIV-Serodiscordant Couples in Resource Limited Settings.

    PubMed

    Sun, Lijun; Wang, Fang; Liu, An; Xin, Ruolei; Zhu, Yunxia; Li, Jianwei; Shao, Ying; Ye, Jiangzhu; Chen, Danqing; Li, Zaicun

    2015-01-01

    Many HIV serodiscordant couples have a strong desire to have their own biological children. Natural conception may be the only choice in some resource limited settings but data about natural conception is limited. Here, we reported our findings of natural conception in HIV serodiscordant couples. Between January 2008 and June 2014, we retrospectively collected data on 91 HIV serodiscordant couples presenting to Beijing Youan Hospital with childbearing desires. HIV counseling, effective ART on HIV infected partners, pre-exposure prophylaxis (PrEP) and post-exposure prophylaxis (PEP) in negative female partners and timed intercourse were used to maximally reduce the risk of HIV transmission. Of the 91 HIV serodiscordant couples, 43 were positive in male partners and 48 were positive in female partners. There were 196 unprotected vaginal intercourses, 100 natural conception and 97 newborns. There were no cases of HIV seroconversion in uninfected sexual partners. Natural conception may be an acceptable option in HIV-serodiscordant couples in resource limited settings if HIV-positive individuals have undetectable viremia on HAART, combined with HIV counseling, PrEP, PEP and timed intercourse.

  19. An Investigation of Effectiveness of Conceptual Change Text-Oriented Instruction on Students' Understanding of Solution Concepts

    ERIC Educational Resources Information Center

    Pinarbasi, Tacettin; Canpolat, Nurtac; Bayrakceken, Samih; Geban, Omer

    2006-01-01

    This study investigated the effect of conceptual change text-oriented instruction over traditional instruction on students' understanding of solution concepts (e.g., dissolving, solubility, factors affecting solubility, concentrations of solutions, types of solutions, physical properties of solutions) and their attitudes towards chemistry. The…

  20. Employment of Gibbs-Donnan-based concepts for interpretation of the properties of linear polyelectrolyte solutions

    USGS Publications Warehouse

    Marinsky, J.A.; Reddy, M.M.

    1991-01-01

    Earlier research has shown that the acid dissociation and metal ion complexation equilibria of linear, weak-acid polyelectrolytes and their cross-linked gel analogues are similarly sensitive to the counterion concentration levels of their solutions. Gibbs-Donnan-based concepts, applicable to the gel, are equally applicable to the linear polyelectrolyte for the accommodation of this sensitivity to ionic strength. This result is presumed to indicate that the linear polyelectrolyte in solution develops counterion-concentrating regions that closely resemble the gel phase of their analogues. Advantage has been taken of this description of linear polyelectrolytes to estimate the solvent uptake by these regions. ?? 1991 American Chemical Society.

  1. Examining student conceptions of the nature of science from two project-based classrooms

    NASA Astrophysics Data System (ADS)

    Moss, David M.

    The purpose of this research was to develop descriptive accounts of precollege students' conceptions of the nature of science from two project-based classrooms, and track those conceptions over the course of an academic year. A model of the nature of science was developed and served as the criterion by which students' beliefs were evaluated. The model distinguishes between two major categories of science, the nature of the scientific enterprise and the nature of scientific knowledge. Five students were selected from each class and interviewed individually for 30-45 minutes each, six times over the year. Data from semi-structured, formal interviewing consisted of audio-recorded interviews which were transcribed verbatim. All passages were coded using codes which corresponded to the premises of the model of the nature of science. Passages in the transcripts were interpreted to develop a summary of the students' conceptions over the year. Qualitative methodologies, especially formal interviewing in conjunction with participant observation, were effective for uncovering students' conceptions of the nature of science, adding to the knowledge base in this field. The research design of the current study was a significant factor in explaining the inconsistencies seen between findings from this study and the literature. This study finds that participants at both classroom sites held fully formed conceptions of the nature of science for approximately 40 percent of the premises across the model. For two-thirds of the elements which comprise the premises, participants held full understandings. Participants held more complete understandings of the nature of scientific knowledge than the nature of the scientific enterprise. Most participants had difficulty distinguishing between science and non-science and held poor understandings of the role of questions in science. Students' beliefs generally remained unchanged over the year. When their conceptions did evolve, project

  2. College biology students' conceptions related to the nature of biological knowledge: Implications for conceptual change

    NASA Astrophysics Data System (ADS)

    Ameny, Gloria Millie Apio

    Adequate understanding of the nature of science is a major goal of science education. Understanding of the evolutionary nature of biological knowledge is a means of reinforcing biology students' understanding of the nature of science. It provides students with the philosophical basis, explanatory ideals, and subject matter-specific views of what counts as a scientifically-acceptable biological explanation. This study examined 121 college introductory biology and advanced zoology students for their conceptions related to the nature of biological knowledge. A 60-item Likert-scale questionnaire called the Nature of Biological Knowledge Scale and student interviews were used as complementary research instruments. Firstly, the study showed that 80--100% of college biology students have an adequate understanding of scientific methods, and that a similar percentage of students had learned the theory of evolution by natural selection in their biology courses. Secondly, the study showed that at least 60--80% of the students do not understand the importance of evolution in biological knowledge. Yet the study revealed that a statistically significant positive correlation exist among students' understanding of natural selection, divergent, and convergent evolutionary models. Thirdly, the study showed that about 20--58% of college students hold prescientific conceptions which, in part, are responsible for students' lack of understanding of the nature of biological knowledge. A statistically significant negative correlation was found among students' prescientific conceptions about basis of biological knowledge and nature of change in biological processes, and their understanding of natural selection and evolutionary models. However, the study showed that students' characteristics such as gender, age, major, or years in college have no statistically significant influence on students' conceptions related to the nature of biological knowledge. Only students' depth of biological

  3. Representations of Fundamental Chemistry Concepts in Relation to the Particulate Nature of Matter

    ERIC Educational Resources Information Center

    Kirbulut, Zubeyde Demet; Beeth, Michael Edward

    2013-01-01

    This study investigated high school students' understanding of fundamental chemistry concepts - states of matter, melting, evaporation, condensation, boiling, and vapor pressure, in relation to their understanding of the particulate nature of matter. A sample of six students (four females and two males) enrolled in a second year chemistry course…

  4. Representations of Fundamental Chemistry Concepts in Relation to the Particulate Nature of Matter

    ERIC Educational Resources Information Center

    Kirbulut, Zübeyde Demet; Beeth, Michael Edward

    2013-01-01

    This study investigated high school students' understanding of fundamental chemistry concepts--states of matter, melting, evaporation, condensation, boiling, and vapor pressure, in relation to their understanding of the particulate nature of matter. A sample of six students (four females and two males) enrolled in a second year chemistry course at…

  5. Teachers' Knowledge Structures for Nature of Science and Scientific Inquiry: Conceptions and Classroom Practice

    ERIC Educational Resources Information Center

    Bartos, Stephen A.; Lederman, Norman G.

    2014-01-01

    Research on nature of science (NOS) and scientific inquiry (SI) has indicated that a teacher's knowledge of each, however well developed, is not sufficient to ensure that these conceptions necessarily manifest themselves in classroom practice (Lederman & Druger, 1985; Lederman, 2007). In light of considerable research that has examined…

  6. Thai and Bangladeshi In-Service Science Teachers' Conceptions of Nature of Science: A Comparative Study

    ERIC Educational Resources Information Center

    Buaraphan, Khajornsak; Abedin Forhad, Ziaul

    2014-01-01

    Understanding of nature of science (NOS) serves as one of the desirable characteristics of science teachers. The current study explored 55 Thai and 110 Bangladeshi in-service secondary science teachers' conceptions of NOS regarding scientific knowledge, scientific method, scientists' work, and scientific enterprise, by using the Myths of Science…

  7. Thai In-Service Science Teachers' Conceptions of the Nature of Science

    ERIC Educational Resources Information Center

    Buaraphan, Khajornsak

    2009-01-01

    Understanding of the Nature of Science (NOS) serves as one of the desirable characteristics of science teachers. The current study attempted to explore 101 Thai in-service science teachers' conceptions of the NOS, particularly scientific knowledge, the scientific method, scientists' work, and scientific enterprise, by using the Myths of Science…

  8. Test-Enhanced Learning of Natural Concepts: Effects on Recognition Memory, Classification, and Metacognition

    ERIC Educational Resources Information Center

    Jacoby, Larry L.; Wahlheim, Christopher N.; Coane, Jennifer H.

    2010-01-01

    Three experiments examined testing effects on learning of natural concepts and metacognitive assessments of such learning. Results revealed that testing enhanced recognition memory and classification accuracy for studied and novel exemplars of bird families on immediate and delayed tests. These effects depended on the balance of study and test…

  9. Students' Conceptions of the Nature of Science: Perspectives from Canadian and Korean Middle School Students

    ERIC Educational Resources Information Center

    Park, Hyeran; Nielsen, Wendy; Woodruff, Earl

    2014-01-01

    This study examined and compared students' understanding of nature of science (NOS) with 521 Grade 8 Canadian and Korean students using a mixed methods approach. The concepts of NOS were measured using a survey that had both quantitative and qualitative elements. Descriptive statistics and one-way multivariate analysis of variances examined the…

  10. Beyond Exemplars and Prototypes as Memory Representations of Natural Concepts: A Clustering Approach

    ERIC Educational Resources Information Center

    Verbeemen, Timothy; Vanpaemel, Wolf; Pattyn, Sven; Storms, Gert; Verguts, Tom

    2007-01-01

    Categorization in well-known natural concepts is studied using a special version of the Varying Abstraction Framework (Vanpaemel, W., & Storms, G. (2006). A varying abstraction framework for categorization. Manuscript submitted for publication; Vanpaemel, W., Storms, G., & Ons, B. (2005). A varying abstraction model for categorization. In B. Bara,…

  11. Thai Pre-Service Science Teachers' Conceptions of the Nature of Science

    ERIC Educational Resources Information Center

    Buaraphan, Khajornsak; Sung-ong, Sunun

    2009-01-01

    The conceptions of the nature of science (NOS), particularly scientific knowledge, scientific method, scientists' work, and scientific enterprise, of 113 Thai pre-service science teachers were was captured by the Myths of Science Questionnaire (MOSQ) in the first semester of the 2008 academic year. The data was quantitatively and qualitatively…

  12. Students' and Teachers' Conceptions of the Nature of Science: A Review of the Research.

    ERIC Educational Resources Information Center

    Lederman, Norman G.

    1992-01-01

    Reviews research from the past 40 years on students' and teachers' conceptions of the nature of science, clarifies the basic assumptions and logic which have guided earlier research efforts, contrasts the results from qualitative and quantitative research, makes recommendations about research methods, and suggests avenues for future research about…

  13. [Plinius and Greek physicians in Rome: the concept of nature and medical critique in Naturalis Historia].

    PubMed

    Hahn, J

    1991-01-01

    Pliny's historical outline of the development of medicine, in Natural History 29.1-27, is our primary source concerning the reception of scientific medicine at Rome during the later Republic and early Empire. Here, as elsewhere, Pliny handles Greek doctors and their medical practices with vehement disapproval. But this attitude, at first glance anti-Hellene, traditionalistic, and critical of his coevals, arises from more deeply rooted notions: a specific conception of nature which can be shown to be the basis of Pliny's critique of medicine and his own times. Reconstruction of this "Plinean" conception reveals a view of nature marked by Stoic terminology and categories, though in fact derivate from various sources, idiosyncratic and characterized by a genuine love of and respect for nature and her creations. True comprehension of the lessons offered by nature, resulting in concrete mores of behaviour and moral categories, as opposed to theory and speculation, is the proper modus operandi for Pliny. And thus, with regard to the human process of self-discovery in the natural world, medicine plays a decisive role--for providential nature displays herself most clearly in the production of healing substances. Pliny notes among the proponents of scientific medicine, a general disregard for nature and her rules, while he finds just the opposite in traditional medicine. His own accomplishment resides not only in the safeguarding of numberless recipies from the world of folk medicine, but also in the facts that he under-pins these traditional methods of healing, and their basic principles, with a specific conception of nature, and that he marks out an exceptionally important place for traditional methods of healing in the canon of general knowledge.

  14. Liquid absorbent solutions for separating nitrogen from natural gas

    DOEpatents

    Friesen, Dwayne T.; Babcock, Walter C.; Edlund, David J.; Lyon, David K.; Miller, Warren K.

    2000-01-01

    Nitrogen-absorbing and -desorbing compositions, novel ligands and transition metal complexes, and methods of using the same, which are useful for the selective separation of nitrogen from other gases, especially natural gas.

  15. A study of Taiwanese children's conceptions of and relation to nature: Curricular and policy implications

    NASA Astrophysics Data System (ADS)

    Dai, Amy Hsin-I.

    The present study investigated children's conceptions of and relations to nature. Understanding the factors that influence them was the goal. The study used the Contextual Model of Learning as the theoretical framework to structure the research questions and data analysis to understand children's nature learning in the personal, sociocultural, and physical contexts that change over time. Twelve children aged 5 and 6 were prompted to draw a picture of themselves in nature. They were interviewed about the sources of those ideas and living experiences, and if they thought photographs of scenery were nature. These twelve children's parents also participated in a survey to study the family influence. I used interpretational analysis to seek for common patterns and themes. Scoring rubrics, coaxial comparison, constant comparison, and the theoretical framework were used to triangulate and investigate influential factors of children's ideas of nature. The study showed that children at this age already had developed a basic conception of what is nature, but also need to learn about the role of human beings in nature and the interrelations of nature in order to develop environmental education ideas. Most children also had a positive feeling toward nature. Children's definitions of nature were developed mainly from what parents and grandparents had told them and their firsthand exposure to nature. Only during the weekend did the children's families have time to visit nature. It was found that most parents in this study stated that they were inspired by nature and were very willing to take their children to nature settings. The most visited natural places that were reported visited were parks in the city and the mountains surrounding the city. However, very often parents missed teachable opportunities to make the experiences with nature meaningful to children. Implications of the study apply to curriculum designers, educators, urban planners, and parents. It is recommended

  16. Anthropology from a Kantian point of view: toward a cosmopolitan conception of human nature.

    PubMed

    Louden, Robert B

    2008-12-01

    Anthropology was a new field of study when Kant first began lecturing on it in 1772, and Kant himself was the first academic to teach regular courses in this area. As is well known, his own approach to anthropology is self-described as 'pragmatic', and Kant's pragmatic anthropology differs markedly from the anthropologies that other early contributors to the new discipline were advocating. In this essay I focus on a fundamental feature of Kant's anthropology that has been under-appreciated in previous discussions; namely, the particular conception of human nature that he believes anthropology, when pursued properly, leads to. I call this conception a cosmopolitan conception of human nature. In addition to establishing the central importance of this idea for Kant's project in anthropology, I also try in this essay to unravel some of its ambiguities and tensions as well as to highlight its underlying moral motives. The cosmopolitan conception of human nature that is central to Kant's anthropology is a further indication of the significance of his anthropology for ethics.

  17. Student concepts of Natural Selection from a resource-based perspective

    NASA Astrophysics Data System (ADS)

    Benjamin, Scott Shawn

    The past two decades have produced a substantial amount of research about the teaching and learning of evolution; however, recent research often lacks a theoretical foundation. Application of a new theoretical framework could help fill the void and improve research about student concepts of evolution. This study seeks to show that a resource-based framework (Hammer et al., 2005) can improve research into student concepts of natural selection. Concepts of natural selection from urban community college students were assessed via qualitative (interviews, written open-response questions, and write/think aloud procedures) and quantitative methods (coded open response analysis, Concept Inventory for Natural Selection (CINS)(Anderson, Fisher, & Norman, 2002). Results showed that students demonstrate four important aspects of resource-based framework: the multi-faceted construction of concepts, context sensitivity/ concept flexibility, at-the-moment activation of resources, and perceptual frames. In open response assessment, evolutionary-gain responses produced significantly different responses than evolutionary-loss questions with: 1) significantly more correct answers for the gain than loss question (Wilcoxon signed rank test, z = -3.68, p=0.0002); 2) more Lamarckian responses to loss than the gain question (Fisher exact, p=0.0039); and significantly different distributions in expanded need vs basic need answers (Fishers exact, p = 0.02). Results from CINS scores showed significant differences in post activity scores between students that held different naive concepts associated with origin of variation, origin of species, differential reproduction, and limited survival suggesting that some naive ideas facilitate learning. Outcomes also suggest that an everyday or self-experience typological perceptual frame is an underlying source of many incorrect ideas about evolution. Interview and write/think aloud assessments propose four process resources applied by students as

  18. Confronting, Representing, and Believing Counterintuitive Concepts: Navigating the Natural and the Supernatural.

    PubMed

    Lane, Jonathan D; Harris, Paul L

    2014-03-01

    Recent research shows that even preschoolers are skeptical; they frequently reject claims from other people when the claims conflict with their own perceptions and concepts. Yet, despite their skepticism, both children and adults come to believe in a variety of phenomena that defy their first-hand perceptions and intuitive conceptions of the world. In this review, we explore how children and adults acquire such concepts. We describe how a similar developmental process underlies mental representation of both the natural and the supernatural world, and we detail this process for two prominent supernatural counterintuitive ideas-God and the afterlife. In doing so, we highlight the fact that conceptual development does not always move in the direction of greater empirical truth, as described within naturalistic domains. We consider factors that likely help overcome skepticism and, in doing so, promote belief in counterintuitive phenomena. These factors include qualities of the learners, aspects of the context, qualities of the informants, and qualities of the information.

  19. 'Natures' and 'Laws': The making of the concept of law of nature - Robert Grosseteste (c. 1168-1253) and Roger Bacon (1214/1220-1292).

    PubMed

    Kedar, Yael; Hon, Giora

    2017-02-01

    Contemporary scholars set the Greek conception of an immanent natural order in opposition to the seventeenth century mechanistic conception of extrinsic laws imposed upon nature from without. By contrast, we argue that in the process of making the concept of law of nature, forms and laws were coherently used in theories of natural causation. We submit that such a combination can be found in the thirteenth century. The heroes of our claim are Robert Grosseteste who turned the idea of corporeal form into the common feature of matter, and Roger Bacon who described the effects of that common feature. Bacon detached the explanatory principle from matter and rendered it independent and therefore external to natural substances. Our plausibility argument, anchored in close reading of the relevant texts, facilitates a coherent conception of both 'natures' and 'laws'.

  20. Teaching Nature of Science to Preservice Science Teachers: A Phenomenographic Study of Chinese Teacher Educators' Conceptions

    NASA Astrophysics Data System (ADS)

    Wan, Zhi Hong; Wong, Siu Ling; Zhan, Ying

    2013-10-01

    Drawing from the phenomenographic perspective, this study investigated Chinese science teacher educators' conceptions of teaching nature of science (NOS) to preservice science teachers through two semi-structured interviews. The subjects were twenty-four science teacher educators in the developed regions in China. Five key dimensions emerged from the data on the conceptions of teaching NOS, including value of teaching NOS, NOS content to be taught, incorporation of NOS instruction in courses, learning of NOS, and role of the teacher. While some of these dimensions share much similarity with those reported in the studies of conceptions of teaching in general, some are distinctively different, which is embedded in some unique features of teaching NOS to preservice science teachers. These key dimensions can constitute the valuable components of the module or course to train science teachers or teacher educators to teach NOS, provide a framework to interpret the practice of teaching NOS, as well as lay a foundation for probing the conceptions of teaching NOS of other groups of subjects (e.g., school teachers' conceptions of teaching NOS) or in other contexts (e.g., teaching NOS to in-service teacher).

  1. Normality and naturalness: a comparison of the meanings of concepts used within veterinary medicine and human medicine.

    PubMed

    Lerner, Henrik; Hofmann, Bjørn

    2011-12-01

    This article analyses the different connotations of "normality" and "being natural," bringing together the theoretical discussion from both human medicine and veterinary medicine. We show how the interpretations of the concepts in the different areas could be mutually fruitful. It appears that the conceptions of "natural" are more elaborate in veterinary medicine, and can be of value to human medicine. In particular they can nuance and correct conceptions of nature in human medicine that may be too idealistic. Correspondingly, the wide ranging conceptions of "normal" in human medicine may enrich conceptions in veterinary medicine, where the discussions seem to be sparse. We do not argue that conceptions from veterinary medicine should be used in human medicine and vice versa, but only that it could be done and that it may well be fruitful. Moreover, there are overlaps between some notions of normal and natural, and further conceptual analysis on this overlap is needed.

  2. Conceptions of the Nature of Science Held by Undergraduate Pre-Service Biology Teachers in South-West Nigeria

    ERIC Educational Resources Information Center

    Adedoyin, A. O.; Bello, G.

    2017-01-01

    This study investigated the conceptions of the nature of science held by pre-service undergraduate biology teachers in South-West, Nigeria. Specifically, the study examined the influence of their gender on their conceptions of the nature of science. The study was a descriptive research of the survey method. The population for the study comprised…

  3. The Electromagnetic Conception of Nature at the Root of the Special and General Relativity Theories and Its Revolutionary Meaning

    ERIC Educational Resources Information Center

    Giannetto, Enrico R. A.

    2009-01-01

    The revolution in XX century physics, induced by relativity theories, had its roots within the electromagnetic conception of Nature. It was developed through a tradition related to Brunian and Leibnizian physics, to the German "Naturphilosophie" and English XIXth physics. The electromagnetic conception of Nature was in some way realized by the…

  4. Natural solution to antibiotic resistance: bacteriophages 'The Living Drugs'.

    PubMed

    Jassim, Sabah A A; Limoges, Richard G

    2014-08-01

    Antibiotics have been a panacea in animal husbandry as well as in human therapy for decades. The huge amount of antibiotics used to induce the growth and protect the health of farm animals has lead to the evolution of bacteria that are resistant to the drug's effects. Today, many researchers are working with bacteriophages (phages) as an alternative to antibiotics in the control of pathogens for human therapy as well as prevention, biocontrol, and therapy in animal agriculture. Phage therapy and biocontrol have yet to fulfill their promise or potential, largely due to several key obstacles to their performance. Several suggestions are shared in order to point a direction for overcoming common obstacles in applied phage technology. The key to successful use of phages in modern scientific, farm, food processing and clinical applications is to understand the common obstacles as well as best practices and to develop answers that work in harmony with nature.

  5. Natural gas production problems : solutions, methodologies, and modeling.

    SciTech Connect

    Rautman, Christopher Arthur; Herrin, James M.; Cooper, Scott Patrick; Basinski, Paul M.; Olsson, William Arthur; Arnold, Bill Walter; Broadhead, Ronald F.; Knight, Connie D.; Keefe, Russell G.; McKinney, Curt; Holm, Gus; Holland, John F.; Larson, Rich; Engler, Thomas W.; Lorenz, John Clay

    2004-10-01

    Natural gas is a clean fuel that will be the most important domestic energy resource for the first half the 21st centtuy. Ensuring a stable supply is essential for our national energy security. The research we have undertaken will maximize the extractable volume of gas while minimizing the environmental impact of surface disturbances associated with drilling and production. This report describes a methodology for comprehensive evaluation and modeling of the total gas system within a basin focusing on problematic horizontal fluid flow variability. This has been accomplished through extensive use of geophysical, core (rock sample) and outcrop data to interpret and predict directional flow and production trends. Side benefits include reduced environmental impact of drilling due to reduced number of required wells for resource extraction. These results have been accomplished through a cooperative and integrated systems approach involving industry, government, academia and a multi-organizational team within Sandia National Laboratories. Industry has provided essential in-kind support to this project in the forms of extensive core data, production data, maps, seismic data, production analyses, engineering studies, plus equipment and staff for obtaining geophysical data. This approach provides innovative ideas and technologies to bring new resources to market and to reduce the overall environmental impact of drilling. More importantly, the products of this research are not be location specific but can be extended to other areas of gas production throughout the Rocky Mountain area. Thus this project is designed to solve problems associated with natural gas production at developing sites, or at old sites under redevelopment.

  6. Evolvability Is an Evolved Ability: The Coding Concept as the Arch-Unit of Natural Selection

    NASA Astrophysics Data System (ADS)

    Janković, Srdja; Ćirković, Milan M.

    2016-03-01

    Physical processes that characterize living matter are qualitatively distinct in that they involve encoding and transfer of specific types of information. Such information plays an active part in the control of events that are ultimately linked to the capacity of the system to persist and multiply. This algorithmicity of life is a key prerequisite for its Darwinian evolution, driven by natural selection acting upon stochastically arising variations of the encoded information. The concept of evolvability attempts to define the total capacity of a system to evolve new encoded traits under appropriate conditions, i.e., the accessible section of total morphological space. Since this is dependent on previously evolved regulatory networks that govern information flow in the system, evolvability itself may be regarded as an evolved ability. The way information is physically written, read and modified in living cells (the "coding concept") has not changed substantially during the whole history of the Earth's biosphere. This biosphere, be it alone or one of many, is, accordingly, itself a product of natural selection, since the overall evolvability conferred by its coding concept (nucleic acids as information carriers with the "rulebook of meanings" provided by codons, as well as all the subsystems that regulate various conditional information-reading modes) certainly played a key role in enabling this biosphere to survive up to the present, through alterations of planetary conditions, including at least five catastrophic events linked to major mass extinctions. We submit that, whatever the actual prebiotic physical and chemical processes may have been on our home planet, or may, in principle, occur at some time and place in the Universe, a particular coding concept, with its respective potential to give rise to a biosphere, or class of biospheres, of a certain evolvability, may itself be regarded as a unit (indeed the arch-unit) of natural selection.

  7. Evolvability Is an Evolved Ability: The Coding Concept as the Arch-Unit of Natural Selection.

    PubMed

    Janković, Srdja; Ćirković, Milan M

    2016-03-01

    Physical processes that characterize living matter are qualitatively distinct in that they involve encoding and transfer of specific types of information. Such information plays an active part in the control of events that are ultimately linked to the capacity of the system to persist and multiply. This algorithmicity of life is a key prerequisite for its Darwinian evolution, driven by natural selection acting upon stochastically arising variations of the encoded information. The concept of evolvability attempts to define the total capacity of a system to evolve new encoded traits under appropriate conditions, i.e., the accessible section of total morphological space. Since this is dependent on previously evolved regulatory networks that govern information flow in the system, evolvability itself may be regarded as an evolved ability. The way information is physically written, read and modified in living cells (the "coding concept") has not changed substantially during the whole history of the Earth's biosphere. This biosphere, be it alone or one of many, is, accordingly, itself a product of natural selection, since the overall evolvability conferred by its coding concept (nucleic acids as information carriers with the "rulebook of meanings" provided by codons, as well as all the subsystems that regulate various conditional information-reading modes) certainly played a key role in enabling this biosphere to survive up to the present, through alterations of planetary conditions, including at least five catastrophic events linked to major mass extinctions. We submit that, whatever the actual prebiotic physical and chemical processes may have been on our home planet, or may, in principle, occur at some time and place in the Universe, a particular coding concept, with its respective potential to give rise to a biosphere, or class of biospheres, of a certain evolvability, may itself be regarded as a unit (indeed the arch-unit) of natural selection.

  8. A natural compromise: a moderate solution to the GMO & "natural" labeling disputes.

    PubMed

    Amaru, Stephanie

    2014-01-01

    In the United States, genetically modified (GM) foods are labeled no differently from their natural counterparts, leaving consumers with no mechanism for deciphering genetically modified food content. The Food and Drug Administration (FDA) has not formally defined the term "natural," which is frequently used on food labels despite consumer confusion as to what it means. The FDA should initiate a notice and comment rulemaking addressing the narrow issue of whether use of the word "natural" should be permitted oil GM food labels. Prohibition of the use of"natural" on genetically modified foods would mitigate consumer deception regarding genetically modified food content without significantly disadvantaging genetically modified food producers.

  9. Solution--What Does It Mean? Helping Linear Algebra Students Develop the Concept While Improving Research Tools

    ERIC Educational Resources Information Center

    DeVries, David; Arnon, Ilana

    2004-01-01

    Twelve linear algebra students were interviewed about the concept of a Solution of a System of Equations. The interviews were analyzed using APOS tools, in particular the ideas of Action, Process, Object and Schema, and Genetic Decomposition. The analysis of the interviews revealed several misconceptions of Solution. The analysis also revealed…

  10. New concepts, experimental approaches, and dereplication strategies for the discovery of novel phytoestrogens from natural sources.

    PubMed

    Michel, Thomas; Halabalaki, Maria; Skaltsounis, Alexios-Leandros

    2013-05-01

    Phytoestrogens constitute an attractive research topic due to their estrogenic profile and their biological involvement in woman's health. Therefore, numerous studies are currently performed in natural products chemistry area aiming at the discovery of novel phytoestrogens. The main classes of phytoestrogens are flavonoids (flavonols, flavanones), isoflavonoids (isoflavones, coumestans), lignans, stilbenoids as well as miscellaneous chemical groups abundant in several edible and/or medicinal plants, belonging mostly to the Leguminosae family. As for other bioactives, the detection of new structures and more potent plant-derived phytoestrogens typically follows the general approaches currently available in the natural product discovery process. Plant-based approaches selected from traditional medicine knowledge and bioguided concepts are routinely employed. However, these approaches are associated with serious disadvantages such as time-consuming, repeated, and labor intensive processes as well as lack of specificity and reproducibility. In recent years, the natural products chemistry became more technology-driven, and several different strategies have been developed. Structure-oriented procedures and miniaturized approaches employing advanced hyphenated analytical platforms have recently emerged. They facilitate significantly not only the discovery of novel phytoestrogens but also the dereplication procedure leading to the anticipation of major drawbacks in natural products discovery. In this review, apart from the traditional concepts followed in phytochemistry for the discovery of novel biologically active compounds, recent applications in the field of extraction, analysis, fractionation, and identification of phytoestrogens will be discussed. Moreover, specific methodologies combining identification of actives and biological evaluation in parallel, such as liquid chromatography-biochemical detection, frontal affinity chromatography-mass spectrometry and pulsed

  11. Analysis of Saudi Arabian middle and high school science teachers' conceptions of the nature of science

    NASA Astrophysics Data System (ADS)

    Almazroa, Hiya Mohammed

    This study was conducted to explore Saudi middle and high school science teachers' conceptions of the Nature of Science (NOS). It also detected the effects of gender, science content major, and years of teaching experience on teachers' conceptions of the NOS. The study included a sample of 786 science teachers (137 male and 649 female) who were teaching in middle and high schools in Riyadh, Saudi Arabia in the 1995-1996 academic year. The study was conducted using a translated version of the Nature of Science Scale (NOSS) developed by Kimball (1967). The scale contains 29 items ranging from "agree" to "disagree", and the scoring of the items ranged from 29 to 87. The lowest score is 29 (1 x 29) and the highest score possible on the test is 87 (3 x 29 items). The data collected was statistically analyzed using descriptive statistics and Analysis of Variance (ANOVA). The study revealed that Saudi science teachers as a group hold numerous misconceptions about the NOS with a significant difference in understanding the NOS between the male and female teachers. The study also showed that teachers with a major in physics held more adequate views than did teachers with other majors. In addition, novice teachers were found to have more adequate conceptions of the NOS than did experienced teachers.

  12. Sperm quality and its relationship to natural and assisted conception: British Fertility Society guidelines for practice.

    PubMed

    Tomlinson, Mathew; Lewis, Sheena; Morroll, David

    2013-09-01

    Reports on the influence of semen parameters on natural or assisted pregnancy are contradictory, suggesting that the many confounding variables which contribute to outcome have not been taken into account. However, it is possible to derive some consensus for both natural and assisted conception by focussing on studies which use WHO-recommended semen analysis on relatively large populations, applying appropriate statistics and accounting for 'female factors'. The concentration of progressively motile sperm has consistently been shown to be the most predictive factor with regard to outcome. Around 64% of studies suggest that a reasonable chance of success with artificial insemination requires at least 5 × 10⁶ motile sperm and this is supported by the WHO's revised reference range for natural conception. Sperm morphology remains controversial, with a lack of standardisation across centres, the adoption of ever-stricter scoring criteria and changing reference values. Antisperm antibodies do not appear to influence outcome independently of sperm motility and agglutination. Sperm DNA damage appears to be related to sperm quality, embryo development and pregnancy loss, yet there remains no consensus on the best testing procedures, clinical reference values and how patients with an adverse result should be managed. In conclusion, laboratories should continue to focus on reducing the uncertainty and improving the quality of their basic semen analysis.

  13. Rate-Limited Organic Solute Sorption to Natural Soil: Concentration, Organic Matter Content, and Solute Effects

    NASA Astrophysics Data System (ADS)

    Smith, J. A.; Riddle, S. A.; Deitsch, J. J.

    2002-05-01

    Sorption of phenanthrene to two soil types and 1,2-dichlorobenzene (DCB) to three soil types was quantified for different incubation times and for different equilibrium aqueous concentrations using a batch sorption methodology. The organic-carbon contents of the soils studied ranged from 0.5 to 30%. A lognormal distributed rate model was used to simulate the kinetic sorption data. The simulations were conducted to determine the optimal untransformed mean and standard deviation for the lognormal distribution of the water-soil mass-transfer coefficients. The 95% confidence regions for these parameters were also determined. The means of the mass-transfer coefficient distributions between experiments were then compared. For phenanthrene sorption to the Woodburn soil (1.3% organic carbon), and for DCB sorption to the Woodburn and Picatinny sand (0.53% organic carbon) soils, the mean mass-transfer rate increased with increasing solute aqueous equilibrium concentration. For phenanthrene sorption to the Picatinny sand and 1,2-dichlorobenzene sorption to the Picatinny peat soil (30% organic carbon), there was no strong relation between the distribution of mass-transfer coefficients and the equilibrium aqueous concentration of the solute. Second, the mean of the distribution of mass-transfer rate coefficients decreased as the organic-carbon content of the sorbent increased. This effect was observed for both solutes. Third, for a given soil and relative concentration (equilibrium solute concentration normalized to aqueous solubility), the means of the distribution of mass-transfer rate coefficients were consistently greater for phenanthrene than for DCB. The mechanistic implications of these observations will be discussed.

  14. The Nature of Science in Science Curricula: Methods and concepts of analysis

    NASA Astrophysics Data System (ADS)

    Ferreira, Sílvia; Morais, Ana M.

    2013-11-01

    The article shows methods and concepts of analysis of the nature of science in science curricula through an exemplary study made in Portugal. The study analyses the extent to which the message transmitted by the Natural Science curriculum for Portuguese middle school considers the nature of science. It is epistemologically and sociologically grounded with particular emphasis on Bernstein's theory of pedagogic discourse and Ziman's conceptualization of science construction. The study used a mixed methodology and followed a dialectical process between the theoretical and the empirical. The results show that the nature of science has a low status in the curriculum with the exception of the external sociological dimension of science. Intra-disciplinary relations between scientific and metascientific knowledge are mostly absent. Recontextualization processes occurred between the two main parts of the curriculum. These results are discussed and their consequences in terms of scientific learning are explored. The mode of analysis used in the study has the potential of highlighting the level of a science curriculum, in terms of specific aspects of the nature of science.

  15. Eulerian-Lagrangian solution of the convection-dispersion equation in natural co-ordinates.

    USGS Publications Warehouse

    Cheng, R.T.; Casulli, V.; Milford, S.N.

    1984-01-01

    The vast majority of numerical investigations of transport phenomena use an Eulerian formulation for the convenience that the computational grids are fixed in space. An Eulerian-Lagrangian method (ELM) of solution for the convection-dispersion equation is discussed and analyzed. The ELM uses the Lagrangian concept in an Eulerian computational grid system.-from Authors

  16. BOOK REVIEW: Critical Phenomena in Natural Sciences: Chaos, Fractals, Selforganization and Disorder: Concepts and Tools

    NASA Astrophysics Data System (ADS)

    Franz, S.

    2004-10-01

    Since the discovery of the renormalization group theory in statistical physics, the realm of applications of the concepts of scale invariance and criticality has pervaded several fields of natural and social sciences. This is the leitmotiv of Didier Sornette's book, who in Critical Phenomena in Natural Sciences reviews three decades of developments and applications of the concepts of criticality, scale invariance and power law behaviour from statistical physics, to earthquake prediction, ruptures, plate tectonics, modelling biological and economic systems and so on. This strongly interdisciplinary book addresses students and researchers in disciplines where concepts of criticality and scale invariance are appropriate: mainly geology from which most of the examples are taken, but also engineering, biology, medicine, economics, etc. A good preparation in quantitative science is assumed but the presentation of statistical physics principles, tools and models is self-contained, so that little background in this field is needed. The book is written in a simple informal style encouraging intuitive comprehension rather than stressing formal derivations. Together with the discussion of the main conceptual results of the discipline, great effort is devoted to providing applied scientists with the tools of data analysis and modelling necessary to analyse, understand, make predictions and simulate systems undergoing complex collective behaviour. The book starts from a purely descriptive approach, explaining basic probabilistic and geometrical tools to characterize power law behaviour and scale invariant sets. Probability theory is introduced by a detailed discussion of interpretative issues warning the reader on the use and misuse of probabilistic concepts when the emphasis is on prediction of low probability rare---and often catastrophic---events. Then, concepts that have proved useful in risk evaluation, extreme value statistics, large limit theorems for sums of independent

  17. Sperm selection in natural conception: what can we learn from Mother Nature to improve assisted reproduction outcomes?

    PubMed Central

    Sakkas, Denny; Ramalingam, Mythili; Garrido, Nicolas; Barratt, Christopher L.R.

    2015-01-01

    BACKGROUND In natural conception only a few sperm cells reach the ampulla or the site of fertilization. This population is a selected group of cells since only motile cells can pass through cervical mucus and gain initial entry into the female reproductive tract. In animals, some studies indicate that the sperm selected by the reproductive tract and recovered from the uterus and the oviducts have higher fertilization rates but this is not a universal finding. Some species show less discrimination in sperm selection and abnormal sperm do arrive at the oviduct. In contrast, assisted reproductive technologies (ART) utilize a more random sperm population. In this review we contrast the journey of the spermatozoon in vivo and in vitro and discuss this in the context of developing new sperm preparation and selection techniques for ART. METHODS A review of the literature examining characteristics of the spermatozoa selected in vivo is compared with recent developments in in vitro selection and preparation methods. Contrasts and similarities are presented. RESULTS AND CONCLUSIONS New technologies are being developed to aid in the diagnosis, preparation and selection of spermatozoa in ART. To date progress has been frustrating and these methods have provided variable benefits in improving outcomes after ART. It is more likely that examining the mechanisms enforced by nature will provide valuable information in regard to sperm selection and preparation techniques in vitro. Identifying the properties of those spermatozoa which do reach the oviduct will also be important for the development of more effective tests of semen quality. In this review we examine the value of sperm selection to see how much guidance for ART can be gleaned from the natural selection processes in vivo. PMID:26386468

  18. Pharmacognosy and reverse pharmacognosy: a new concept for accelerating natural drug discovery.

    PubMed

    Do, Quoc-Tuan; Bernard, Philippe

    2004-11-01

    Combinatorial chemistry and high-throughput screening (HTS) have led to the identification of numerous agents that are active and selective in vitro. Identifying drugs that are active in vivo, however, remains a challenge. Traditional medicinal cures based on natural materials have proven useful for many populations worldwide, representing huge and disperse tracts of knowledge that are sometimes neglected in Western research due to differences in the concepts of illness. In this review we introduce a new approach, termed 'reverse pharmacognosy' (from diverse molecules to plants), which can be coupled with pharmacognosy (from biodiverse plants to molecules). Reverse pharmacognosy utilizes new techniques, such as HTS, virtual screening and a knowledge database containing the traditional uses of plants. Integrating pharmacognosy and reverse pharmacognosy in the research process may provide an efficient and rapid tool for natural drug discovery.

  19. Preservice Biology Teachers' Conceptions About the Tentative Nature of Theories and Models in Biology

    NASA Astrophysics Data System (ADS)

    Reinisch, Bianca; Krüger, Dirk

    2016-11-01

    In research on the nature of science, there is a need to investigate the role and status of different scientific knowledge forms. Theories and models are two of the most important knowledge forms within biology and are the focus of this study. During interviews, preservice biology teachers (N = 10) were asked about their understanding of theories and models. They were requested to give reasons why they see theories and models as either tentative or certain constructs. Their conceptions were then compared to philosophers' positions (e.g., Popper, Giere). A category system was developed from the qualitative content analysis of the interviews. These categories include 16 conceptions for theories (n tentative = 11; n certain = 5) and 18 conceptions for models (n tentative = 10; n certain = 8). The analysis of the interviews showed that the preservice teachers gave reasons for the tentativeness or certainty of theories and models either due to their understanding of the terms or due to their understanding of the generation or evaluation of theories and models. Therefore, a variety of different terminology, from different sources, should be used in learning-teaching situations. Additionally, an understanding of which processes lead to the generation, evaluation, and refinement or rejection of theories and models should be discussed with preservice teachers. Within philosophy of science, there has been a shift from theories to models. This should be transferred to educational contexts by firstly highlighting the role of models and also their connections to theories.

  20. Students' Conceptions of the Nature of Science: Perspectives from Canadian and Korean Middle School Students

    NASA Astrophysics Data System (ADS)

    Park, Hyeran; Nielsen, Wendy; Woodruff, Earl

    2014-05-01

    This study examined and compared students' understanding of nature of science (NOS) with 521 Grade 8 Canadian and Korean students using a mixed methods approach. The concepts of NOS were measured using a survey that had both quantitative and qualitative elements. Descriptive statistics and one-way multivariate analysis of variances examined the quantitative data while a conceptually clustered matrix classified the open-ended responses. The country effect could explain 3-12 % of the variances of subjectivity, empirical testability and diverse methods, but it was not significant for the concepts of tentativeness and socio-cultural embeddedness of science. The open-ended responses showed that students believed scientific theories change due to errors or discoveries. Students regarded empirical evidence as undeniable and objective although they acknowledged experiments depend on theories or scientists' knowledge. The open responses revealed that national situations and curriculum content affected their views. For our future democratic citizens to gain scientific literacy, science curricula should include currently acknowledged NOS concepts and should be situated within societal and cultural perspectives.

  1. Confronting, Representing, and Believing Counterintuitive Concepts: Navigating the Natural and the Supernatural

    PubMed Central

    Lane, Jonathan D.; Harris, Paul. L.

    2014-01-01

    Recent research shows that even preschoolers are skeptical; they frequently reject claims from other people when the claims conflict with their own perceptions and concepts. Yet, despite their skepticism, both children and adults come to believe in a variety of phenomena that defy their first-hand perceptions and intuitive conceptions of the world. In this review, we explore how children and adults acquire such concepts. We describe how a similar developmental process underlies mental representation of both the natural and the supernatural world, and we detail this process for two prominent supernatural counterintuitive ideas—God and the afterlife. In doing so, we highlight the fact that conceptual development does not always move in the direction of greater empirical truth, as described within naturalistic domains. We consider factors that likely help overcome skepticism, and in doing so promote belief in counterintuitive phenomena. These factors include qualities of the learners, aspects of the context, qualities of the informants, and qualities of the information. PMID:24683418

  2. Advanced onboard storage concepts for natural gas-fueled automotive vehicles

    NASA Technical Reports Server (NTRS)

    Remick, R. J.; Elkins, R. H.; Camara, E. H.; Bulicz, T.

    1984-01-01

    The evaluation of several advanced concepts for storing natural gas at reduced pressure is presented. The advanced concepts include adsorption on high surface area carbon, adsorption in high porosity zeolite, storage in clathration compounds, and storage by dissolution in liquid solvents. High surface area carbons with high packing density are the best low pressure storage mediums. A simple mathematical model is used to compare adsorption storage on a state of the art carbon with compression storage. The model indicates that a vehicle using adsorption storage of natural gas at 3.6 MPa will have 36 percent of the range, on the EPA city cycle, of a vehicle operating on a compression storage system having the same physical size and a peak storage pressure of 21 MPa. Preliminary experiments and current literature suggest that the storage capacity of state of the art carbons could be improved by as much as 50 percent, and that adsorption systems having a capacity equal to compression storage at 14 MPa are possible without exceeding a maximum pressure of 3.6 MPa.

  3. Nature as an engineer: one simple concept of a bio-inspired functional artificial muscle.

    PubMed

    Schmitt, S; Haeufle, D F B; Blickhan, R; Günther, M

    2012-09-01

    The biological muscle is a powerful, flexible and versatile actuator. Its intrinsic characteristics determine the way how movements are generated and controlled. Robotic and prosthetic applications expect to profit from relying on bio-inspired actuators which exhibit natural (muscle-like) characteristics. As of today, when constructing a technical actuator, it is not possible to copy the exact molecular structure of a biological muscle. Alternatively, the question may be put how its characteristics can be realized with known mechanical components. Recently, a mechanical construct for an artificial muscle was proposed, which exhibits hyperbolic force-velocity characteristics. In this paper, we promote the constructing concept which is made by substantiating the mechanical design of biological muscle by a simple model, proving the feasibility of its real-world implementation, and checking their output both for mutual consistency and agreement with biological measurements. In particular, the relations of force, enthalpy rate and mechanical efficiency versus contraction velocity of both the construct's technical implementation and its numerical model were determined in quick-release experiments. All model predictions for these relations and the hardware results are now in good agreement with the biological literature. We conclude that the construct represents a mechanical concept of natural actuation, which is suitable for laying down some useful suggestions when designing bio-inspired actuators.

  4. Professional Development of Elementary and Science Teachers in a Summer Science Camp: Changing Nature of Science Conceptions

    ERIC Educational Resources Information Center

    Karaman, Ayhan

    2016-01-01

    Many countries all over the world have recently integrated nature of science (NOS) concepts into their science education standards. Providing professional support to teachers about NOS concepts is crucially important for successful implementation of the standards. For this purpose, a summer science camp was offered to elementary and science…

  5. The World Atlas of Desertification assessment concept for conscious land use solutions

    NASA Astrophysics Data System (ADS)

    Cherlet, Michael; Ivits, Eva; Kutnjak, Hrvoje; Smid, Marek; Sommer, Stefan; Zucca, Claudio

    2015-04-01

    Land degradation and desertification are complex phenomena that result in environmental damage, economic inefficiency and social inequity and are reflected by a reducing productive capacity of the land and soil. Research indicated that they are driven by a multiple but a limited number of causal aspects that unbalance the capacity of the environment system to sustainably produce ecosystem services and economic value. Competition for land, driven by societal needs or economic opportunities, adds further stress on the land resources. To address these complex global challenges, a monitoring and assessment system offering up-to-date information on the status and trends of land degradation and their causes and effects is needed to provide science-based routes for possible land use solutions. The assessment concept that has been outlined for the compilation of the new World Atlas of Desertification (WAD) confronts this complexity by converging evidence of stress on the land system caused by various issues. These issues relate to sets of dynamics of the human-environment system and include changing agricultural or pastoral land use and management practices, changing population and societal aspects, changing aridity and drought. The WAD describes the issues, spatially documents their change, whenever data is available, highlights the importance of the issues in relation to land degradation processes and illustrates the integrated assessment concepts. The first step is the preparation of solid global data layers that are related to, or express aspects that can be related to, land-system productivity dynamics and status. These can be used for identifying and evaluating the interaction of spatial variables with the land-system productivity dynamics. Initial analysis of the land productivity dynamics within stratified land cover/use areas, such as the global croplands, show substantial differences in the extension, geographic location and possible related causes of potentially

  6. Challenging the Concept of Natural Distributions: Global Change Turns Trees Into Weeds

    NASA Astrophysics Data System (ADS)

    Gleadow, R.; O'Leary, B.; Burd, M.

    2015-12-01

    National parks and nature reserves are set aside to preserve certain ecosystems, reflecting species distributions at a moment in time. Changing climate and fire dynamics can mean that the species most suited to that area are different, leading new tree species to 'invade' the conservation areas. Pittosporum undulatum is an invasive tree native tree species with a natural range from southeast Queensland to Eastern Victoria, Australia. Soon after European settlement this species became a popular ornamental tree in gardens and was planted outside of its natural range across the continent and introduced to the USA (where it is known as Victorian Box), the Hawaiian Islands, Jamaica, southern Africa and the Azores. The reason this is important is because high density of P. undulatum lead to reduced biodiversity and often the complete suppression of regeneration of exiting forest trees. In Australia, changes in fire dynamics have played a major part in its in dominance. New strategies for forest management were proposed by Gleadow an Ashton in the 1980s, but lack of action has led us to predict that the entire Dandenong Ranges, near Melbourne, will be invaded within 25 years resulting in the loss of a major recreational and conservation area. This is a model of the type of problems that can be expected as the climate envelope for species changes in the coming century, challenging the very concept of a "native ".

  7. RMS Titanic and the emergence of new concepts on consortial nature of microbial events.

    PubMed

    Cullimore, D Roy; Pellegrino, Charles; Johnston, Lori

    2002-01-01

    The RMS Titanic sank in 1912 and created a historical event that still ripples through time. Stories were told and lessons learned but the science has only just begun. Today the fading remains of the ship resemble the hanging gardens of Babylon except that it is not plants that drape the walls but complex microbial growths called rusticles. These organisms have been found to be not a species, like plants and animals, but to be structures created by complex communities of bacterial species. Like the discovery of tube worms in the mid-oceanic vents, the nature of these rusticles presents another biological discovery of a fundamental nature. Essentially these microbial consortia on the RMS Titanic have generated structures of a mass that would rival whales and elephants while gradually extracting the iron from the steel. Rusticle-like consortia appear to play many roles within the environment, and it is perhaps the RMS Titanic that is showing that there is a new way to understand the form, function, and nature of microorganisms. This understanding would develop by considering the bacteria not as individual species functioning independently but as consortia of species functioning in community structures within a common habitat. This concept, if adopted, would change dramatically the manner in which a microbial ecologist and any scientist or engineer would view the occurrence of a slime, encrustation, biocolloid, rust flake, iron pan, salt deposit, and perhaps even some of the diseases that remain unexplained as a disease of unknown cause.

  8. 'Normal', 'natural', 'good' or 'good-enough' birth: examining the concepts.

    PubMed

    Darra, Susanne

    2009-12-01

    In the face of increasing intervention in childbirth, 'normal birth' is currently being promoted by the World Health Organization, national governments, professional bodies and other organisations throughout the world. This paper takes a postmodernist stance and explores the idea of the 'normal' before going on to analyse normal childbirth, referring to concepts of the normal and the natural. It refers to historical developments in childbearing and lay organisations along with research relating to women's views of childbirth, to question the appropriateness of using 'normal' to describe the very individual experiences of childbirth. It laments the way in which women have been treated and arguably continue to be 'cared for' in maternity/obstetric services. It adds to the current discussion by recalling psychoanalytical theory and philosophical analysis to conclude with a call for future consideration of the 'good-enough' birth instead of concentrating on promoting normal birth which is very difficult, if not impossible to define in retrospect, or to prospectively promote.

  9. Investigating the Nature of Third Grade Students' Experiences with Concept Maps to Support Learning of Science Concepts

    ERIC Educational Resources Information Center

    Merrill, Margaret L.

    2012-01-01

    To support and improve effective science teaching, educators need methods to reveal student understandings and misconceptions of science concepts and to offer all students an opportunity to reflect on their own knowledge construction and organization. Students can benefit by engaging in scientific activities in which they build personal…

  10. An Investigation into the Relationship between Students' Conceptions of the Particulate Nature of Matter and Their Understanding of Chemical Bonding

    ERIC Educational Resources Information Center

    Othman, Jazilah; Treagust, David F.; Chandrasegaran, A. L.

    2008-01-01

    A thorough understanding of chemical bonding requires familiarity with the particulate nature of matter. In this study, a two-tier multiple-choice diagnostic instrument consisting of ten items (five items involving each of the two concepts) was developed to assess students' understanding of the particulate nature of matter and chemical bonding so…

  11. Solitary wave solutions of nonlinear financial markets: data-modeling-concept-practicing

    NASA Astrophysics Data System (ADS)

    Ma, Jin-Long; Ma, Fei-Te

    2007-07-01

    This paper seeks to solve the difficult nonlinear problem in financial markets on the complex system theory and the nonlinear dynamics principle, with the data-model-concept-practice issue-oriented reconstruction of the phase space by the high frequency trade data. In theory, we have achieved the differentiable manifold geometry configuration, discovered the Yang-Mills functional in financial markets, obtained a meaningful conserved quantity through corresponding space-time non-Abel localization gauge symmetry transformation, and derived the financial solitons, which shows that there is a strict symmetry between manifold fiber bundle and guage field in financial markets. In practical applications of financial markets, we have repeatedly carried out experimental tests in a fluctuant evolvement, directly simulating and validating the existence of solitons by researching the price fluctuations (society phenomena) using the same methods and criterion as in natural science and in actual trade to test the stock Guangzhou Proprietary and the futures Fuel Oil in China. The results demonstrate that the financial solitons discovered indicates that there is a kind of new substance and form of energy existing in financial trade markets, which likely indicates a new science paradigm in the economy and society domains beyond physics.

  12. Dynamics of a Definition: A Framework to Analyse Student Construction of the Concept of Solution to a Differential Equation

    ERIC Educational Resources Information Center

    Raychaudhuri, Debasree

    2008-01-01

    In this note we develop a framework that makes explicit the inherent dynamic structure of certain mathematical definitions by means of the four facets of context-entity-process-object. These facets and their interrelations are then used to capture and interpret specific aspects of student constructions of the concept of solution to first order…

  13. The Electromagnetic Conception of Nature at the Root of the Special and General Relativity Theories and its Revolutionary Meaning

    NASA Astrophysics Data System (ADS)

    Giannetto, Enrico R. A.

    2009-06-01

    The revolution in XX century physics, induced by relativity theories, had its roots within the electromagnetic conception of Nature. It was developed through a tradition related to Brunian and Leibnizian physics, to the German Naturphilosophie and English XIXth physics. The electromagnetic conception of Nature was in some way realized by the relativistic dynamics of Poincaré of 1905. Einstein, on the contrary, after some years, linked relativistic dynamics to a semi-mechanist conception of Nature. He developed general relativity theory on the same ground, but Hilbert formulated it starting from the electromagnetic conception of Nature. Here, a comparison between these two conceptions is proposed in order to understand the conceptual foundations of special relativity within the context of the changing world views. The whole history of physics as well as history of science can be considered as a conflict among different worldviews. Every theory, as well as every different formulation of a theory implies a different worldview: a particular image of Nature implies a particular image of God (atheism too has a particular image of God) as well as of mankind and of their relationship. Thus, it is very relevant for scientific education to point out which image of Nature belongs to a particular formulation of a theory, which image comes to dominate and for which ideological reason.

  14. Toward a new concept of "natural balance" in oral estroprogestin contraception.

    PubMed

    Chabbert-Buffet, Nathalie; Gerris, Jan; Jamin, Christian; Lello, Stefano; Lete, Inaki; Lobo, Paloma; Nappi, Rossella E; Pintiaux, Axelle

    2013-10-01

    The Pill has undergone many changes since its first appearance some 50 years ago. Key developments included the reduction of ethinylestradiol doses and the synthesis of new progestins in order to increase safety, compliance and efficiency. Low-dose combined oral contraceptives (COCs) are currently the preferred option for millions of women. Due to this widespread use, it has been argued that the safety of COCs should be even better, raising the threshold for excellence. Yet in spite of major improvements, there is still an associated risk of venous thromboembolism (VTE). The next step in COCs' evolution should take total estrogenicity and hepatic estro-androgenic balance into account. The focus on the estrogen component--which has not changed in 50 years--has yielded a new class of natural estrogen pills. Following the introduction of a first quadriphasic pill, a monophasic estradiol pill based on the concept of "natural balance" was subsequently made available. These recent achievements could represent a step forward in the evolution of COCs and pave the way for better safety.

  15. Nature of fluid flows in differentially heated cylindrical container filled with a stratified solution

    NASA Technical Reports Server (NTRS)

    Wang, Jai-Ching

    1992-01-01

    Semiconductor crystals such as Hg(1-x)Cd(x)Te grown by unidirectional solidification Bridgmann method have shown compositional segregations in both the axial and radial directions. Due to the wide separation between the liquidus and the solidus of its pseudobinary phase diagram, there is a diffusion layer of higher HgTe content built up in the melt near the melt-solid interface which gives a solute concentration gradient in the axial direction. Because of the higher thermal conductivity in the melt than that in the crystal there is a thermal leakage through the fused silica crucible wall near the melt-solid interface. This gives a thermal gradient in the radial direction. Hart (1971), Thorpe, Hutt and Soulsby (1969) have shown that under such condition a fluid will become convectively unstable as a result of different diffusivities of temperature and solute. It is quite important to understand the effects of this thermosolute convection on the compositional segregation in the unidirectionally solidified crystals. To reach this goal, we start with a simplified problem. We study the nature of fluid flows of a stratified solution in a cylindrical container with a radial temperature gradient. The cylindrical container wall is considered to be maintained at a higher temperature than that at the center of the solution and the solution in the lower gravitational direction has higher solute concentration which decrease linearly to a lower concentration and then remain constant to the top of the solution. The sample solution is taken to be salt water.

  16. The evolution of cellular computing: nature's solution to a computational problem.

    PubMed

    Landweber, L F; Kari, L

    1999-10-01

    How do cells and nature 'compute'? They read and 'rewrite' DNA all the time, by processes that modify sequences at the DNA or RNA level. In 1994, Adleman's elegant solution to a seven-city directed Hamiltonian path problem using DNA launched the new field of DNA computing, which in a few years has grown to international scope. However, unknown to this field, two ciliated protozoans of the genus Oxytricha had solved a potentially harder problem using DNA several million years earlier. The solution to this problem, which occurs during the process of gene unscrambling, represents one of nature's ingenious solutions to the problem of the creation of genes. RNA editing, which can also be viewed as a computational process, offers a second algorithm for the construction of functional genes from encrypted pieces of the genome.

  17. Children's Conceptions of Air Pressure: Exploring the Nature of Conceptual Change.

    ERIC Educational Resources Information Center

    Tytler, Russell

    1998-01-01

    Constructs case studies of individuals to explore the way conceptions change over time, and the difficulties presented by the concept of atmospheric pressure. Evaluates different structural theories of conceptual change. Contains 62 references. (DDR)

  18. Natural convection in binary gases due to horizontal thermal and solutal gradients

    NASA Technical Reports Server (NTRS)

    Weaver, J. A.; Viskanta, R.

    1991-01-01

    The influence of augmenting and opposing thermal and solutal buoyancy forces on natural convection of binary gases due to horizontal temperature and concentration gradients is examined through comparison of smoke flow visualization and measured temperature and concentration distributions with numerical predictions. The observed flow at the cold wall was unsteady for opposing body forces. The same basic flow structure was observed, but the unsteady flow intensifies as the opposing solutal buoyancy force increases as compared to the thermal buoyancy force. Comparison of predicted and measured temperatures and concentrations is fair overall, but the steady-state analytical model fails to predict the unsteady flow and heat and mass transport for opposing body forces.

  19. Transport of reacting solutes in porous media: Relation between mathematical nature of problem formulation and chemical nature of reactions

    USGS Publications Warehouse

    Rubin, Jacob

    1983-01-01

    Examples involving six broad reaction classes show that the nature of transport-affecting chemistry may have a profound effect on the mathematical character of solute transport problem formulation. Substantive mathematical diversity among such formulations is brought about principally by reaction properties that determine whether (1) the reaction can be regarded as being controlled by local chemical equilibria or whether it must be considered as being controlled by kinetics, (2) the reaction is homogeneous or heterogeneous, (3) the reaction is a surface reaction (adsorption, ion exchange) or one of the reactions of classical chemistry (e.g., precipitation, dissolution, oxidation, reduction, complex formation). These properties, as well as the choice of means to describe them, stipulate, for instance, (1) the type of chemical entities for which a formulation's basic, mass-balance equations should be written; (2) the nature of mathematical transformations needed to change the problem's basic equations into operational ones. These and other influences determine such mathematical features of problem formulations as the nature of the operational transport-equation system (e.g., whether it involves algebraic, partial-differential, or integro-partial-differential simultaneous equations), the type of nonlinearities of such a system, and the character of the boundaries (e.g., whether they are stationary or moving). Exploration of the reasons for the dependence of transport mathematics on transport chemistry suggests that many results of this dependence stem from the basic properties of the reactions' chemical-relation (i.e., equilibrium or rate) equations.

  20. A conceptual change analysis of nature of science conceptions: The deep roots and entangled vines of a conceptual ecology

    NASA Astrophysics Data System (ADS)

    Johnston, Adam Thomas

    This research used theories of conceptual change to analyze learners' understandings of the nature of science (NOS). Ideas regarding the NOS have been advocated as vital aspects of science literacy, yet learners at many levels (students and teachers) have difficulty in understanding these aspects in the way that science literacy reforms advocate. Although previous research has shown the inadequacies in learners' NOS understandings and have documented ways by which to improve some of these understandings, little has been done to show how these ideas develop and why learners' preexisting conceptions of NOS are so resistant to conceptual change. The premise of this study, then, was to describe the nature of NOS conceptions and of the conceptual change process itself by deeply analyzing the conceptions of individual learners. Toward this end, 4 individuals enrolled in a physical science course designed for preservice elementary teachers were selected to participate in a qualitative research study. These individuals answered questionnaires, surveys, direct interview questions, and a variety of interview probes (e.g., critical incidents, responses to readings/videos, reflections on coursework, card sorting tasks, etc.) which were administered throughout the duration of a semester. By utilizing these in-depth, qualitative probes, learners' conceptions were not only assessed but also described in great detail, revealing the source of their conceptions as well as identifying many instances in which a learner's directly stated conception was contradictory to that which was reflected by more indirect probes. As a result of this research, implications regarding NOS conceptions and their development have been described. In addition, various descriptions of conceptual change have been further refined and informed. Especially notable, the influence of a learner's conceptual ecology and its extrarational influences on conceptual change have been highlighted. It is argued that

  1. Microbially-enhanced redox solution reoxidation for sweetening sour natural gas

    SciTech Connect

    Rai, C.

    1995-06-01

    About twenty five percent of natural gas produced in the United States is sour containing significant volumes of hydrogen sulfide and other contaminants. Liquid redox processes remove hydrogen sulfide from natural gas. Aqueous solution of chelated ferric ions oxidize the hydrogen sulfide to elemental sulfur. The reduced iron chelate is then oxidized by contact with air and recycled. This requires expensive equipment for regeneration, costly chemicals and the process is usually energy intensive. Recent studies show that the ferric ion regeneration rates are substantially enhanced in presence of acidophilic bacteria. The specific objectives of this project are to advance the technology and improve the economics of the commercial iron-based chelate processes utilizing biologically-enhanced reoxidation of the redox solutions used in these processes, such as LO-CAT II and SulFerox.

  2. Natural micro-scale heterogeneity induced solute and nanoparticle retardation in fractured crystalline rock.

    PubMed

    Huber, F; Enzmann, F; Wenka, A; Bouby, M; Dentz, M; Schäfer, T

    2012-05-15

    We studied tracer (Tritiated Water (HTO); Tritium replaces one of the stable hydrogen atoms in the H(2)O molecule) and nanoparticle (quantum dots (QD)) transport by means of column migration experiments and comparison to 3D CFD modeling. Concerning the modeling approach, a natural single fracture was scanned using micro computed tomography (μCT) serving as direct input for the model generation. The 3D simulation does not incorporate any chemical processes besides the molecular diffusion coefficient solely reflecting the impact of fracture heterogeneity on mass (solute and nanoparticles) transport. Complex fluid velocity distributions (flow channeling and flowpath heterogeneity) evolve as direct function of fracture geometry. Both experimental and simulated solute and colloidal breakthrough curves show heavy tailing (non-Fickian transport behavior), respectively. Regarding the type of quantum dots and geochemical conditions prevailing (Grimsel ground water chemistry, QD and diorite surface charge, respectively and porosity of the Äspö diorite drill core) experimental breakthrough of the quantum dots always arrives faster than the solute tracer in line with the modeling results. Besides retardation processes like sorption, filtration, straining or matrix diffusion, the results show that natural 3D fracture heterogeneity represents an important additional retardation mechanism for solutes and colloidal phases. This is clearly verified by the numerical simulations, where the 3D real natural fracture geometry and the resulting complex flow velocity distribution is the only possible process causing solute/nanoparticle retardation. Differences between the experimental results and the simulations are discussed with respect to uncertainties in the μCT measurements and experimental and simulation boundary conditions, respectively.

  3. Removal Of Copper From Aqueous Solutions By Using Natural And Fe-Modified Clinoptilolite

    NASA Astrophysics Data System (ADS)

    Lipovský, Marek; Sirotiak, Maroš; Soldán, Maroš

    2015-06-01

    Removal of copper from aqueous solution on the natural and modified clinoptilolite was studied under static conditions. Batch adsorptions of copper were performed to investigate the effects of contact time and initial metal ion concentration. The Freundlich and Langmuir adsorption isotherms were used to analyse the experimental data. The kinetic analyses of the adsorption processes were performed using the pseudo-first-order and pseudo-second-order kinetic models.

  4. The effectiveness of conceptual change texts and concept clipboards in learning the nature of science

    NASA Astrophysics Data System (ADS)

    Çil, Emine; Çepni, Salih

    2016-01-01

    Background: One of the most important goals of science education is to enable students to understand the nature of science (NOS). However, generally regular science teaching in classrooms does not help students improve informed NOS views. Purpose: This study investigated the influence of an explicit reflective conceptual change approach compared with an explicit reflective inquiry-oriented approach on seventh graders' understanding of NOS. Sample: The research was conducted with seventh grade students. A total of 44 students participated in the study. Design and method: The study was an interpretive study because this study focused on the meanings that students attach to target aspects of NOS. Participants were divided into two groups, each consisting of 22 students. One of the groups learned NOS with an explicit reflective conceptual change approach. The requirements of conceptual change were provided through the use of conceptual change texts and concept cartoons. The other group learned NOS with an explicit reflective inquiry-oriented approach. The data were collected through open-ended questionnaires and semi-structured interviews. These instruments were employed in a pre-test, a post-test and a delayed test. Students' views of the aspects of NOS were categorized as naive, transitional and informed. Results: The result of this study indicated that before receiving instruction, most of the participants had transitional views of the tentative, empirical and imaginative and creative aspects of the NOS, and they had naive understandings of the distinction between observation and inference. The instruction in the experimental group led to a 60% - a 25% increase in the number of students who possessed an informed understanding of the tentative, empirical, creative and observation and inference aspect of the NOS. The instruction in the control group led to a 30% - a 15% increase in the informed NOS views. Conclusion: The explicit reflective conceptual change approach

  5. Upscaling solute transport in naturally fractured porous media with the continuous time random walk method

    SciTech Connect

    Geiger, S.; Cortis, A.; Birkholzer, J.T.

    2010-04-01

    Solute transport in fractured porous media is typically 'non-Fickian'; that is, it is characterized by early breakthrough and long tailing and by nonlinear growth of the Green function-centered second moment. This behavior is due to the effects of (1) multirate diffusion occurring between the highly permeable fracture network and the low-permeability rock matrix, (2) a wide range of advection rates in the fractures and, possibly, the matrix as well, and (3) a range of path lengths. As a consequence, prediction of solute transport processes at the macroscale represents a formidable challenge. Classical dual-porosity (or mobile-immobile) approaches in conjunction with an advection-dispersion equation and macroscopic dispersivity commonly fail to predict breakthrough of fractured porous media accurately. It was recently demonstrated that the continuous time random walk (CTRW) method can be used as a generalized upscaling approach. Here we extend this work and use results from high-resolution finite element-finite volume-based simulations of solute transport in an outcrop analogue of a naturally fractured reservoir to calibrate the CTRW method by extracting a distribution of retention times. This procedure allows us to predict breakthrough at other model locations accurately and to gain significant insight into the nature of the fracture-matrix interaction in naturally fractured porous reservoirs with geologically realistic fracture geometries.

  6. Trapping the lead ion in multi-components aqueous solution by natural clinoptilolite.

    PubMed

    Tao, Yu Fei; Qiu, Yue; Fang, Shu Yu; Liu, Zhu Yun; Wang, Ying; Zhu, Jian Hua

    2010-08-15

    To study whether natural clinoptilolite could selectively capture Pb(2+) ion in the aqueous solution containing salt and glycine as well as nitrosamines, the natural zeolite was utilized in the complex solution with pH value of 1.2 in comparison with other porous materials such as zeolite NaZSM-5 and activated carbon. Clinoptilolite exhibited the highest capability in adsorbing Pb(2+) ion in the solution at 37 degrees C, achieving the capacity of 7 mg/g, two times more than that by other zeolites and six times over that by activated carbon, and the adsorption equilibrium could be achieved within 2h. The impacts of solid-liquid ratio, initial concentration of Pb(2+) and the competition of other metal ions or volatile nitrosamines on the adsorption were examined, and the change in Gibbs energy for the ion-exchanged of Pb(2+) ion by clinoptilolite was discussed, through which the ion-exchange process was proven to be spontaneous. Moreover, both the selectivity of clinoptilolite toward Pb(2+) ion in complex solution and the venial toxicity of clinoptilolite on the viability of RAW264.7 cells were investigated in this article.

  7. Outcomes of Nature of Science Instruction along a Context Continuum: Preservice Secondary Science Teachers' Conceptions and Instructional Intentions

    ERIC Educational Resources Information Center

    Bell, Randy L.; Mulvey, Bridget K.; Maeng, Jennifer L.

    2016-01-01

    This investigation examined outcomes associated with nature of science (NOS) instruction along a science-content context continuum on the development of secondary preservice science teachers' conceptions of and plans to teach NOS, moving beyond the common dichotomy of contextualized versus noncontextualized instruction. Participants comprised six…

  8. Using the History of Research on Sickle Cell Anemia to Affect Preservice Teachers' Conceptions of the Nature of Science.

    ERIC Educational Resources Information Center

    Howe, Eric M.

    This paper examines how using a series of lessons developed from the history of research on sickle cell anemia affects preservice teacher conceptions of the nature of science (NOS). The importance of a pedagogy that has students do science through an integral use of the history of science is effective at enriching students' NOS views is presented.…

  9. An Examination of the Documentary Film "Einstein and Eddington" in Terms of Nature of Science Themes, Philosophical Movements, and Concepts

    ERIC Educational Resources Information Center

    Kapucu, Munise Seçkin

    2016-01-01

    This study aims to examine nature of science themes, philosophical movements, and overall concepts covered in the documentary film, "Einstein and Eddington". A qualitative research method was used. In this study, the documentary film "Einstein and Eddington," the viewing time of which is 1 hour and 28 minutes, was used as the…

  10. Changing High School Students' Conceptions of the Nature of Science: The Partnership for Research and Education in Plants (PREP)

    ERIC Educational Resources Information Center

    Brooks, Eric Dwayne

    2011-01-01

    This study investigated whether participation in the Partnership for Research and Education in Plants (PREP), a long-term authentic plant research project, in conjunction with explicit verses implicit instruction can change high school students' conceptions of the nature of science (NOS). The participants included a total of 134 students comprised…

  11. Realist Ontology and Natural Processes: A Semantic Tool to Analyze the Presentation of the Osmosis Concept in Science Texts

    ERIC Educational Resources Information Center

    Spinelli Barria, Michele; Morales, Cecilia; Merino, Cristian; Quiroz, Waldo

    2016-01-01

    In this work, we developed an ontological tool, based on the scientific realism of Mario Bunge, for the analysis of the presentation of natural processes in science textbooks. This tool was applied to analyze the presentation of the concept of osmosis in 16 chemistry and biology books at different educational levels. The results showed that more…

  12. Urban e-Mobility - Challenges and potential solutions using the example of the "E3W" concept vehicle

    NASA Astrophysics Data System (ADS)

    Perterer, M.; Martin, P.; Lochner, H.

    2014-05-01

    Due to the increasing number of people in urban areas, there is a need for affordable individual transportation. Limited space in cities together with the need for a significant reduction of pollution will lead to new mobility concepts in the near future. The aim of these concepts is not replacing the car itself, but to supply an additional personal transportation solution with local zero emission. Therefore, electrical powered vehicle concepts may be used. Due to the limited energy density and high cost of current Li-ion batteries, a significant weight reduction of the vehicle could lead to acceptable range and cost. In order to develop an affordable urban concept, the requirements for this kind of vehicle also have to be adjusted in comparison to conventional cars. This concept, the so called "E3W", combines the advantages of a two-wheeler with those of a four-wheeler, resulting in a lightweight and compact vehicle. This concept accommodates space for two persons with luggage and guarantees a high level of safety including wind and weather protection. The overall measures of this vehicle are smaller than current compact cars and allow therefore better use in cities. In order to fulfill technical and commercial requirements, a load carrying, short fiber reinforced thermoplastic body structure is chosen, combining good weight specific mechanical properties and low production costs. This highly integrated body structure also provides the body cover all in one. Pultruded glass fiber reinforced plastic (GFRP) beams are used as the backbone for the vehicle by carrying the main loads, the front crash structure and the rear swingarm. Finally, two prototypes are built to investigate the driving behavior, proof the concept and the suitability for daily use.

  13. The contribution of nature to people: Applying concepts of values and properties to rate the management importance of natural elements.

    PubMed

    Smith, Michael J; Wagner, Christian; Wallace, Ken J; Pourabdollah, Amir; Lewis, Loretta

    2016-06-15

    An important, and yet unresolved question in natural resource management is how best to manage natural elements and their associated values to ensure human wellbeing. Specifically, there is a lack of measurement tools to assess the contribution of nature to people. We present one approach to overcome this global issue and show that the preferred state of any system element, in terms of realising human values, is a function of element properties. Consequently, natural resource managers need to understand the nature of the relationships between element properties and values if they are to successfully manage for human wellbeing. In two case studies of applied planning, we demonstrate how to identify key element properties, quantify their relationships to priority human values, and combine this information to model the contribution of elements to human wellbeing. In one of the two case studies we also compared the modelling outputs with directly elicited stakeholder opinions regarding the importance of the elements for realising the given priority values. The two, largely congruent outputs provide additional support for the approach. The study shows that rating sets of elements on their relative overall value for human wellbeing, or utility, provides critical information for subsequent management decisions and a basis for productive new research. We consider that the described approach is broadly applicable within the domain of natural resource management.

  14. Designing an Illustrated Food Web to Teach Ecological Concepts: Challenges and Solutions.

    ERIC Educational Resources Information Center

    Godkin, Celia M.

    1999-01-01

    Argues that food webs are an efficient method through which to communicate the core idea of ecology--that all living things are interconnected. Assesses the challenges and solutions to using illustrated food webs. (Author/CCM)

  15. School Students' Conceptions about Biodiversity Loss: Definitions, Reasons, Results and Solutions

    ERIC Educational Resources Information Center

    Kilinc, Ahmet; Yesiltas, Namik Kemal; Kartal, Tezcan; Demiral, Ümit; Eroglu, Baris

    2013-01-01

    Environmental degradation stemming from anthropocentric causes threatens the biodiversity more than ever before, leading scholars to warn governments about the impending consequences of biodiversity loss (BL). At this point, it is of great importance to study the public's conceptions of BL in order to identify significant educational implications.…

  16. Natural Hazard Problem and Solution Definition in the News Media: the Case of Tropical Storm Allison

    NASA Astrophysics Data System (ADS)

    Lindquist, Eric; Mosher-Howe, Katrina

    2010-05-01

    Focusing events such as natural or technological disasters can have significant impacts on public policy and planning in both the near and long term. These impacts can manifest at different temporal scales ranging from the period of immediate attention and disaster relief through the period of recovery and reconstruction and beyond. These impacts and associated decisions can be studied in retrospect and understood as not only short-term reactions, but as long-term components of subsequent natural hazard planning and public policy. By studying in detail how an event was defined, and the policy and planning alternatives that were raised or recommended in response to a disaster event, we can better understand the role that disaster-related focusing events play in the long-term evolution of a community's public policy, infrastructural planning efforts, and responses to natural disasters. This paper will use a focusing event framework to explore the local and regional policy impacts over time of a major urban flood in Houston, Texas, Tropical Storm Allison. Tropical Storm Allison (TSA), dropped 36 inches of rain on Houston over a period of four days in early June 2001, and was responsible for 22 deaths, 70,000 flood damaged homes, and 5 billion in damage to the region. The primary data source for this effort is a database of 500 articles from the major regional newspaper, the Houston Chronicle, over the period of 2001 through 2008. These articles were coded for multiple variables, including, cause, effect and impact (financial and social), blame, problem and solution definition and solution acceptance). This paper focuses primarily on the measures of problem definition (how was TSA, as an event, defined in the media, for example, as an act of God, or as a result of poor planning or decision making, etc), and on solution definition (what solutions were proposed to mitigate or adapt to future storms of this magnitude, how were they linked to the definition of the problem

  17. A simple protocol for the visual discrimination of natural cyclodextrins in aqueous solution using perichromic probes

    NASA Astrophysics Data System (ADS)

    Nandi, Leandro G.; Nicoleti, Celso R.; Stock, Rafaela I.; Barboza, Tainá A.; Andreaus, Jürgen; Machado, Vanderlei G.

    2015-02-01

    Three synthesized compounds, 4-(4-nitrostyryl)phenol, 2,6-dibromo-4-(2,4-dinitrobenzylideneamino)phenol and 2,6-dichloro-4-(2,4-dinitrobenzylideneamino)phenol, were deprotonated to generate the perichromic dyes 2b, 3b and 4b, respectively. These dyes were used as probes to investigate the micropolarity of natural cyclodextrins (CyDs) and it was observed that they interact differently with the CyDs according to the molecular structure of the dye and the diameter of the CyD. The solvatochromic bands of the dyes that interacted with the CyDs were bathochromically shifted, suggesting that the probes were transferred to the hydrophobic interior of the CyD in aqueous solution. Dyes 2b and 4b were found to be very selective for α-CyD and γ-CyD, respectively, while β- and γ-CyD changed the color of the solution of compound 3b. These dyes were then successfully used in a simple assay that allows the naked-eye discrimination of natural CyDs in aqueous solution, without the need for expensive techniques.

  18. The Online Dissemination of Nature-Health Concepts: Lessons from Sentiment Analysis of Social Media Relating to "Nature-Deficit Disorder".

    PubMed

    Palomino, Marco; Taylor, Tim; Göker, Ayse; Isaacs, John; Warber, Sara

    2016-01-19

    Evidence continues to grow supporting the idea that restorative environments, green exercise, and nature-based activities positively impact human health. Nature-deficit disorder, a journalistic term proposed to describe the ill effects of people's alienation from nature, is not yet formally recognized as a medical diagnosis. However, over the past decade, the phrase has been enthusiastically taken up by some segments of the lay public. Social media, such as Twitter, with its opportunities to gather "big data" related to public opinions, offers a medium for exploring the discourse and dissemination around nature-deficit disorder and other nature-health concepts. In this paper, we report our experience of collecting more than 175,000 tweets, applying sentiment analysis to measure positive, neutral or negative feelings, and preliminarily mapping the impact on dissemination. Sentiment analysis is currently used to investigate the repercussions of events in social networks, scrutinize opinions about products and services, and understand various aspects of the communication in Web-based communities. Based on a comparison of nature-deficit-disorder "hashtags" and more generic nature hashtags, we make recommendations for the better dissemination of public health messages through changes to the framing of messages. We show the potential of Twitter to aid in better understanding the impact of the natural environment on human health and wellbeing.

  19. Methods and Devices for Fighting Natural Fires Within a New Concept of Control of Natural and Man-Made Disasters

    NASA Astrophysics Data System (ADS)

    Grishin, A. M.; Zima, V. P.; Kasymov, D. P.

    2014-07-01

    Developments of methods and devices for localization and suppression of natural fires are presented. These developments have been created with account taken of the knowledge on the frame structure. With them, one can destroy, by relatively small energy actions, the most vulnerable parts of the fire front: the zones of pyrolysis and mixing of combustible pyrolysis products with the air oxygen.

  20. Reaction of trace mercury in natural gas with dilute polysulfide solutions in a packed column

    SciTech Connect

    Not Available

    1991-12-01

    This paper reports that the natural gas produced around the world can contain traces of mercury which have to be removed. It is difficult to purify gas to desired mercury levels using conventional techniques. By scrubbing with dilute polysulfide solution, the residual mercury in the gas can be removed from about 0.1 to below 0.01 ppb, a reduction of 90%. In this system, the gas is passed through a packed tower wetted with a solution containing 3 ppm of polysulfide salt. Stainless steel packings are effective for this application. In addition to promoting gas-liquid contact, the stainless steel packings adsorb and concentrate polysulfides which react with Hg in the gas to form insoluble HgS, and thus remove Hg from the gas.

  1. A Resource for Eliciting Student Alternative Conceptions: Examining the Adaptability of a Concept Inventory for Natural Selection at the Secondary School Level

    NASA Astrophysics Data System (ADS)

    Lucero, Margaret M.; Petrosino, Anthony J.

    2016-07-01

    The Conceptual Inventory of Natural Selection (CINS) is an example of a research-based instrument that assesses conceptual understanding in an area that contains well-documented alternative conceptions. Much of the CINS's use and original validation has been relegated to undergraduate settings, but the information learned from student responses on the CINS can also potentially be a useful resource for teachers at the secondary level. Because of its structure, the CINS can have a role in eliciting alternative conceptions and induce deeper conceptual understanding by having student ideas leveraged during instruction. In a first step toward this goal, the present study further investigated the CINS's internal properties by having it administered to a group (n = 339) of students among four different biology teachers at a predominantly Latino, economically disadvantaged high school. In addition, incidences of the concept inventory's use among the teachers' practices were collected for support of its adaptability at the secondary level. Despite the teachers' initial enthusiasm for the CINS's use as an assessment tool in the present study, results from a principal components analysis demonstrate inconsistencies between the original and present validations. Results also reveal how the teachers think CINS items may be revised for future use among secondary student populations.

  2. Darwin's "Imaginary Illustrations": Creatively Teaching Evolutionary Concepts & the Nature of Science

    ERIC Educational Resources Information Center

    Love, Alan C.

    2010-01-01

    An overlooked feature of Darwin's work is his use of "imaginary illustrations" to show that natural selection is competent to produce adaptive, evolutionary change. When set in the context of Darwin's methodology, these thought experiments provide a novel way to teach natural selection and the nature of science.

  3. Student Conceptions of Ionic Compounds in Solution and the Influences of Sociochemical Norms on Individual Learning

    ERIC Educational Resources Information Center

    Warfa, Abdi-Rizak M.

    2013-01-01

    Using the symbolic interactionist perspective that meaning is constituted as individuals interact with one another, this study examined how group thinking during cooperative inquiry-based activity on chemical bonding theories shaped and influenced college students' understanding of the properties of ionic compounds in solution. The analysis…

  4. Innovative Learning Solutions in New Communities: Opportunities and Challenges to Teachers' Conceptions of Workspace

    ERIC Educational Resources Information Center

    Costley, Debra

    2007-01-01

    This article explores the possibilities and opportunities created by large-scale property developers for new ways of learning and working in master-planned communities. The discussion is based on the findings from research of one developer's innovative solutions to learning in newly developed communities and specifically draws on data from one…

  5. Student Learning of Thermochemical Concepts in the Context of Solution Calorimetry.

    ERIC Educational Resources Information Center

    Greenbowe, Thomas J.; Meltzer, David E.

    2003-01-01

    Analyzes student performance on solution calorimetry problems in an introductory university chemistry class. Includes data from written classroom exams for 207 students and an extensive longitudinal interview with a student. Indicates learning difficulties, most of which appear to originate from failure to understand, that net increases and…

  6. Exploring Fundamental Concepts in Aqueous Solution Conductivity: A General Chemistry Laboratory Exercise

    ERIC Educational Resources Information Center

    Nyasulu, Frazier; Stevanov, Kelly; Barlag, Rebecca

    2010-01-01

    Using a conductivity sensor, a temperature sensor, and a datalogger, fundamental factors that affect conductivity are explored. These factors are (i) concentration, (ii) temperature, (iii) ion charge, and (iv) size and or mass of anion. In addition, the conductivities of a number of other solutions are measured. This lab has been designed to…

  7. Water and Solute Transport in the Shallow Subsurface of a Natural Levee

    NASA Astrophysics Data System (ADS)

    Newman, A.; Keim, R.

    2008-12-01

    In riverine wetlands, river channels are separated from backswamps by natural levees that form adjacent to the channel by sediment deposition during floods. The conventional conceptual framework is that backswamp water is impounded and disconnected from surface flow; however, layered sediments, shrink-swell clays, roots and decayed organic matter, and animal burrows likely form preferential pathways for subsurface flow and may substantially affect water and solute exchange between wetlands and river channels. To test the hypothesis that preferential flow is an important pathway of subsurface water movement through natural levees, we measured hydraulic gradients and solute tracers in a 5 x 5 m grid of 19 shallow (2m) monitoring wells within a large representative elementary volume (300 m3) of natural levee in the Atchafalaya Basin, Louisiana. In addition to measuring transient responses to precipitation, we constructed a small reservoir on the backswamp side of the levee to simulate a seasonal hydraulic gradient from the swamp to the adjacent river channel. Results indicate rapid response of water levels in all monitoring wells to the imposed hydraulic gradient as well as rain events, which included two tropical cyclones. In contrast, tracer response was highly variable, both spatially and across events, indicating a complex relationship between subsurface flow processes and water chemistry. Groundwater chemistry indicated spatially variable flowpaths. In some wells, hydraulic response coincided with a chemical shift toward low-conductivity surface water; however, other wells showed similar hydraulic responses but no change in tracer concentrations or even a shift toward higher-conductivity water that was presumably stored in the soil matrix. This spatial variation in tracer response indicates multiple mechanisms of hydraulic response, each of which has important implications for biogeochemical interactions between backswamps and channels in the shallow subsurface

  8. Nature of Science and Science Content Learning - The Relation Between Students' Nature of Science Understanding and Their Learning About the Concept of Energy

    NASA Astrophysics Data System (ADS)

    Michel, Hanno; Neumann, Irene

    2017-01-01

    Besides viewing knowledge about the nature of science (NOS) as important for its own value with respect to scientific literacy, an adequate understanding of NOS is expected to improve science content learning by fostering the ability to interrelate scientific concepts and, thus, coherently acquire scientific content knowledge. However, there is a lack of systematic investigations, which clarify the relations between NOS and science content learning. In this paper, we present the results of a study, conducted to investigate how NOS understanding relates to students' acquisition of a proper understanding of the concept of energy. A total of 82 sixth and seventh grade students received an instructional unit on energy, with 41 of them receiving generic NOS instruction beforehand. This NOS instruction, however, did not result in students having higher scores on the NOS instrument. Thus, correlational analyses were performed to investigate how students' NOS understanding prior to the energy unit related to their learning about science content. Results show that a more adequate understanding of NOS might relate to students' perspective on the concept of energy and might support them in understanding the nature of energy as a theoretical concept. Students with higher NOS understanding, for example, seemed to be more capable of learning how to relate the different energy forms to each other and to justify why they can be subsumed under the term of energy. Further, we found that NOS understanding may also be related to students' approach toward energy degradation—a concept that can be difficult for students to master—while it does not seem to have a substantive impact on students' learning gain regarding energy forms, transformation, or conservation.

  9. Concepts and solutions for future-proof health information systems and health networks.

    PubMed

    Blobel, Bernd

    2003-01-01

    Based on shared care information systems' requirements for high level interoperability, a generic component architecture has been derived. For implementing, running and maintaining acceptable and useable health information systems components, all views of the ISO Reference Model--Open Distributed Processing have to be considered. Following the Model Driven Architecture (MDA) paradigm, a reference model as well as concept-representing domain models both independent of platforms must be specified, which are combined and harmonised as well as automatically transferred into the platform-specific models using appropriate tools.

  10. Supply Chain Based Solution to Prevent Fuel Tax Evasion: Proof of Concept Final Report

    SciTech Connect

    Capps, Gary J; Lascurain, Mary Beth; Franzese, Oscar; Earl, Dennis Duncan; West, David L; McIntyre, Timothy J; Chin, Shih-Miao; Hwang, Ho-Ling; Connatser, Raynella M; Lewis Sr, Samuel Arthur; Moore, Sheila A

    2011-12-01

    The goal of this research was to provide a proof-of-concept (POC) system for preventing non-taxable (non-highway diesel use) or low-taxable (jet fuel) petrochemical products from being blended with taxable fuel products and preventing taxable fuel products from cross-jurisdiction evasion. The research worked to fill the need to validate the legitimacy of individual loads, offloads, and movements by integrating and validating, on a near-real-time basis, information from global positioning system (GPS), valve sensors, level sensors, and fuel-marker sensors.

  11. Using nurses' natural language entries to build a concept-oriented terminology for patients' chief complaints in the emergency department.

    PubMed

    Travers, Debbie A; Haas, Stephanie W

    2003-01-01

    Information about the chief complaint (CC), also known as the patient's reason for seeking emergency care, is critical for patient prioritization for treatment and determination of patient flow through the emergency department (ED). Triage nurses document the CC at the start of the ED visit, and the data are increasingly available in electronic form. Despite the clinical and operational significance of the CC to the ED, there is no standard CC terminology. We propose the construction of concept-oriented nursing terminologies from the actual language used by experts. We use text analysis to extract CC concepts from triage nurses' natural language entries. Our methodology for building the nursing terminology utilizes natural language processing techniques and the Unified Medical Language System.

  12. A new approach to evaluate natural zeolite ability to sorb lead (Pb) from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Drosos, Evangelos I. P.; Karapanagioti, Hrissi K.

    2013-04-01

    Lead (Pb) is a hazardous pollutant commonly found in aquatic ecosystems. Among several methods available, the addition of sorbent amendments to soils or sediments is attractive, since its application is relatively simple, while it can also be cost effective when a low cost and re-usable sorbent is used; e.g. natural zeolites. Zeolites are crystalline aluminosilicates with a three-dimensional structure composed of a set of cavities occupied by large ions and water molecules. Zeolites can accommodate a wide variety of cations, such as Na+, K+, Ca2+, Mg2+, which are rather loosely held and can readily be exchanged for others in an aqueous solution. Natural zeolites are capable of removing cations, such as lead, from aqueous solutions by ion exchange. There is a wide variation in the cation exchange capacity (CEC) of natural zeolites because of the different nature of various zeolites cage structures, natural structural defects, adsorbed ions, and their associated gangue minerals. Naturally occurring zeolites are rarely pure and are contaminated to varying degrees by other minerals, such as clays and feldspars, metals, quartz, or other zeolites as well. These impurities affect the CEC even for samples originated from the same region but from a different source. CEC of the material increases with decreasing impurity content. Potentially exchangeable ions in such impurities do not necessarily participate in ion exchange mechanism, while, in some cases, impurities may additionally block the access to active sites. For zeoliferous rocks having the same percentage of a zeolitic phase, the CEC increases with decreasing Si/Al ratio, as the more Si ions are substituted by Al ions, the more negative the valence of the matrix becomes. Sodium seems to be the most effective exchangeable ion for lead. On the contrary, it is unlikely that the potassium content of the zeolite would be substituted. A pretreatment with high concentration solutions of Na, such as 2 M NaCl, can

  13. New fundamental evidence of non-classical structure in the combination of natural concepts.

    PubMed

    Aerts, D; Sozzo, S; Veloz, T

    2016-01-13

    We recently performed cognitive experiments on conjunctions and negations of two concepts with the aim of investigating the combination problem of concepts. Our experiments confirmed the deviations (conceptual vagueness, underextension, overextension etc.) from the rules of classical (fuzzy) logic and probability theory observed by several scholars in concept theory, while our data were successfully modelled in a quantum-theoretic framework developed by ourselves. In this paper, we isolate a new, very stable and systematic pattern of violation of classicality that occurs in concept combinations. In addition, the strength and regularity of this non-classical effect leads us to believe that it occurs at a more fundamental level than the deviations observed up to now. It is our opinion that we have identified a deep non-classical mechanism determining not only how concepts are combined but, rather, how they are formed. We show that this effect can be faithfully modelled in a two-sector Fock space structure, and that it can be exactly explained by assuming that human thought is the superposition of two processes, a 'logical reasoning', guided by 'logic', and a 'conceptual reasoning', guided by 'emergence', and that the latter generally prevails over the former. All these findings provide new fundamental support to our quantum-theoretic approach to human cognition.

  14. Exploring the Relationship between Secondary Science Teachers' Subject Matter Knowledge and Knowledge of Student Conceptions While Teaching Evolution by Natural Selection

    ERIC Educational Resources Information Center

    Lucero, Margaret M.; Petrosino, Anthony J.; Delgado, Cesar

    2017-01-01

    The fundamental scientific concept of evolution occurring by natural selection is home to many deeply held alternative conceptions and considered difficult to teach. Science teachers' subject matter knowledge (SMK) and the pedagogical content knowledge (PCK) component of knowledge of students' conceptions (KOSC) can be valuable resources for…

  15. Solving problems on base of concepts formalization of language image and figurative meaning of the natural-language constructs

    NASA Astrophysics Data System (ADS)

    Bisikalo, Oleg V.; Cieszczyk, Sławomir; Yussupova, Gulbahar

    2015-12-01

    Building of "clever" thesaurus by algebraic means on base of concepts formalization of language image and figurative meaning of the natural-language constructs in the article are proposed. A formal theory based on a binary operator of directional associative relation is constructed and an understanding of an associative normal form of image constructions is introduced. A model of a commutative semigroup, which provides a presentation of a sentence as three components of an interrogative language image construction, is considered.

  16. Growing three-dimensional biomorphic graphene powders using naturally abundant diatomite templates towards high solution processability

    NASA Astrophysics Data System (ADS)

    Chen, Ke; Li, Cong; Shi, Liurong; Gao, Teng; Song, Xiuju; Bachmatiuk, Alicja; Zou, Zhiyu; Deng, Bing; Ji, Qingqing; Ma, Donglin; Peng, Hailin; Du, Zuliang; Rümmeli, Mark Hermann; Zhang, Yanfeng; Liu, Zhongfan

    2016-11-01

    Mass production of high-quality graphene with low cost is the footstone for its widespread practical applications. We present herein a self-limited growth approach for producing graphene powders by a small-methane-flow chemical vapour deposition process on naturally abundant and industrially widely used diatomite (biosilica) substrates. Distinct from the chemically exfoliated graphene, thus-produced biomorphic graphene is highly crystallized with atomic layer-thickness controllability, structural designability and less noncarbon impurities. In particular, the individual graphene microarchitectures preserve a three-dimensional naturally curved surface morphology of original diatom frustules, effectively overcoming the interlayer stacking and hence giving excellent dispersion performance in fabricating solution-processible electrodes. The graphene films derived from as-made graphene powders, compatible with either rod-coating, or inkjet and roll-to-roll printing techniques, exhibit much higher electrical conductivity (~110,700 S m-1 at 80% transmittance) than previously reported solution-based counterparts. This work thus puts forward a practical route for low-cost mass production of various powdery two-dimensional materials.

  17. On the viscosity of natural hyper-saline solutions and its importance: The Dead Sea brines

    NASA Astrophysics Data System (ADS)

    Weisbrod, Noam; Yechieli, Yoseph; Shandalov, Semion; Lensky, Nadav

    2016-01-01

    The relationship between the density, temperature and viscosity of hypersaline solutions, both natural and synthetic, is explored. An empirical equation of the density-viscosity relationship as a function of temperature was developed for the Dead Sea brine and its dilutions. The viscosity levels of the Dead Sea brine (density of 1.24 ṡ 103 kg/m3; viscosity of 3.6 mPa s at 20 °C) and of the more extremely saline natural brine (density of 1.37 ṡ 103 kg/m3) were found to be ∼3 and ∼10 times greater than that of fresh water, respectively. The combined effect of the above changes in viscosity and density on the hydraulic conductivity is reduction by a factor of 3-7. The chemical composition significantly affects the viscosity of brines with similar densities, whereby solutions with a higher Mg/Na ratio have higher viscosity. This explains the extremely high viscosity of the Dead Sea and related Mg-rich brines in comparison with the much lower values of NaCl and KCl brines with similar density. Possible impacts of the results include reduced settling velocity of grains in hypersaline viscous brines and changing hydraulic dynamics at the freshwater-saltwater and the vicinity of sinkholes.

  18. Growing three-dimensional biomorphic graphene powders using naturally abundant diatomite templates towards high solution processability

    PubMed Central

    Chen, Ke; Li, Cong; Shi, Liurong; Gao, Teng; Song, Xiuju; Bachmatiuk, Alicja; Zou, Zhiyu; Deng, Bing; Ji, Qingqing; Ma, Donglin; Peng, Hailin; Du, Zuliang; Rümmeli, Mark Hermann; Zhang, Yanfeng; Liu, Zhongfan

    2016-01-01

    Mass production of high-quality graphene with low cost is the footstone for its widespread practical applications. We present herein a self-limited growth approach for producing graphene powders by a small-methane-flow chemical vapour deposition process on naturally abundant and industrially widely used diatomite (biosilica) substrates. Distinct from the chemically exfoliated graphene, thus-produced biomorphic graphene is highly crystallized with atomic layer-thickness controllability, structural designability and less noncarbon impurities. In particular, the individual graphene microarchitectures preserve a three-dimensional naturally curved surface morphology of original diatom frustules, effectively overcoming the interlayer stacking and hence giving excellent dispersion performance in fabricating solution-processible electrodes. The graphene films derived from as-made graphene powders, compatible with either rod-coating, or inkjet and roll-to-roll printing techniques, exhibit much higher electrical conductivity (∼110,700 S m−1 at 80% transmittance) than previously reported solution-based counterparts. This work thus puts forward a practical route for low-cost mass production of various powdery two-dimensional materials. PMID:27819652

  19. An inverse problem solution to the flow of tracers in naturally fractured reservoirs

    SciTech Connect

    Jetzabeth Ramirez S.; Fernando Samaniego V.; Fernando Rodriguez; Jesus Rivera R.

    1994-01-20

    This paper presents a solution for the inverse problem to the flow of tracers in naturally fractured reservoirs. The models considered include linear flow in vertical fractures, radial flow in horizontal fractures, and cubic block matrix-fracture geometry. The Rosenbrock method for nonlinear regression used in this study, allowed the estimation of up to six parameters for the cubic block matrix fracture geometry. The nonlinear regression for the three cases was carefully tested against syntetical tracer concentration responses affected by random noise, with the objective of simulating as close as possible step injection field data. Results were obtained within 95 percent confidence limits. The sensitivity of the inverse problem solution on the main parameters that describe this flow problem was investigated. The main features of the nonlinear regression program used in this study are also discussed. The procedure of this study can be applied to interpret tracer tests in naturally fractured reservoirs, allowing the estimation of fracture and matrix parameters of practical interest (longitudinal fracture dispersivity alpha, matrix porosity phi2, fracture half-width w, matrix block size d, matrix diffusion coefficient D2 and the adsorption constant kd). The methodology of this work offers a practical alternative for tracer flow tests interpretation to other techniques.

  20. Radiation effects on bifurcation and dual solutions in transient natural convection in a horizontal annulus

    SciTech Connect

    Luo, Kang; Yi, Hong-Liang Tan, He-Ping

    2014-05-15

    Transitions and bifurcations of transient natural convection in a horizontal annulus with radiatively participating medium are numerically investigated using the coupled lattice Boltzmann and direct collocation meshless (LB-DCM) method. As a hybrid approach based on a common multi-scale Boltzmann-type model, the LB-DCM scheme is easy to implement and has an excellent flexibility in dealing with the irregular geometries. Separate particle distribution functions in the LBM are used to calculate the density field, the velocity field and the thermal field. In the radiatively participating medium, the contribution of thermal radiation to natural convection must be taken into account, and it is considered as a radiative term in the energy equation that is solved by the meshless method with moving least-squares (MLS) approximation. The occurrence of various instabilities and bifurcative phenomena is analyzed for different Rayleigh number Ra and Prandtl number Pr with and without radiation. Then, bifurcation diagrams and dual solutions are presented for relevant radiative parameters, such as convection-radiation parameter Rc and optical thickness τ. Numerical results show that the presence of volumetric radiation changes the static temperature gradient of the fluid, and generally results in an increase in the flow critical value. Besides, the existence and development of dual solutions of transient convection in the presence of radiation are greatly affected by radiative parameters. Finally, the advantage of LB-DCM combination is discussed, and the potential benefits of applying the LB-DCM method to multi-field coupling problems are demonstrated.

  1. [Adsorption of Phosphate by Lanthanum Hydroxide/Natural Zeolite Composites from Low Concentration Phosphate Solution].

    PubMed

    Lin, Jian-wei; Wang, Hong; Zhan, Yan-hui; Chen, Dong-mei

    2016-01-15

    A series of composites of lanthanum hydroxide/natural zeolite ( La( OH) 3/NZ composites) were prepared by co-precipitation method, and these composites were used as adsorbents to remove phosphate from aqueous solution. The phosphate adsorption capacities of different composites prepared with different precipitated pH values were compared in batch mode. The adsorption characteristics of phosphate from aqueous solution on the La(OH)3/NZ composite prepared with the precipitated pH value of 11 was investigated using batch experiments. The results showed that the La(OH)3/NZ composite prepared with the precipitated pH values of 5-7 and 13 had a low adsorption capacity for phosphate in aqueous solution, while the La( OH) 3/NZ composites prepared with the precipitated pH values of 9-12 exhibited much higher phosphate adsorption capacity. The phosphate adsorption capacity of the La (OH)3/NZ composite increased with the increase of the precipitated pH value from 9 to 11, but remained basically unchanged with the increase of the precipitated pH value from 11 to 12. The equilibrium adsorption data of phosphate from aqueous solution on the La ( OH ) 3/NZ composite prepared with the precipitated pH value of 11 could be described by the Langmuir isotherm model with the predicted maximum phosphate adsorption of 44 mg x g(-1) (phosphate solution pH 7 and 30 degrees C). The kinetic data of phosphate adsorption from low concentration phosphate solution on the La(OH)3/NZ composite prepared with the precipitated pH value of 11 well followed a pseudo-second-order model. The presence of Cl- and SO4(2-) in low concentration phosphate solution had no negative effect on phosphate adsorption onto the La(OH)3/NZ composite prepared with the precipitated pH value of 11, while the presence of HCO3- slightly inhibited the adsorption of phosphate. Coexisting humic acid had a negative effect on the adsorption of phosphate at low concentration on the La(OH)3/NZ composite prepared with the

  2. Removal of phosphate from aqueous solutions and sewage using natural and surface modified coir pith.

    PubMed

    Krishnan, K Anoop; Haridas, Ajit

    2008-04-01

    Iron impregnated coir pith (CP-Fe-I) can be effectively used for the removal of phosphate from aqueous streams and sewage. Iron impregnation on natural coir pith was carried out by drop by drop addition method. The effect of various factors such as pH, initial concentration of phosphate, contact time and adsorbent dose on phosphate adsorption was studied by batch technique. The pH at 3.0 favored the maximum adsorption of phosphate from aqueous solutions. The effect of pH on phosphate adsorption was explained by pH(zpc), phosphate speciation in solution and affinity of anions towards the adsorbent sites. A comparative study of the adsorption of phosphate using CP-Fe-I and CP (coir pith) was made and results show that the former one is five to six times more effective than the latter. Kinetic studies revealed that the adsorption process followed a pseudo-second order kinetic model. Adsorption followed Langmuir isotherm model. Column studies were conducted to examine the utility of the investigated adsorbent for the removal of phosphate from continuously flowing aqueous solutions.

  3. Pyrene and phenanthrene sorption to model and natural geosorbents in single- and binary-solute systems.

    PubMed

    Zhang, Jing; Séquaris, Jean-Marie; Narres, Hans-Dieter; Vereecken, Harry; Klumpp, Erwin

    2010-11-01

    Sorption of pyrene and phenanthrene to model (illite and charcoal) and natural (Yangtze sediment) geosorbents were investigated by batch techniques using fluorescence spectroscopy. A higher adsorption of phenanthrene was observed with all sorbents, which is related to the better accessibility of smaller molecules to micropores in the molecular sieve sorbents. In addition, pyrene sorption in binary-solute systems with a constant initial concentration of phenanthrene (0.1 μmol L(-1) or 2 μmol L(-1)) was studied. A 0.1 μmol L(-1) concentration of phenanthrene causes no competitive effect on the pyrene sorption. A 2 μmol L(-1) concentration of phenanthrene significantly suppresses the sorption of pyrene, especially in the low concentration range; nonlinearity of the pyrene sorption isotherms thus decreases. The competitive effect of 2 μmol L(-1) phenanthrene on the pyrene sorption is overestimated by the ideal adsorbed solution theory (IAST) using the fitted single sorption results of both solutes. An adjustment of the IAST application by taking into account the molecular sieve effect is proposed, which notably improves the IAST prediction for the competitive effect.

  4. Multi-period natural gas market modeling Applications, stochastic extensions and solution approaches

    NASA Astrophysics Data System (ADS)

    Egging, Rudolf Gerardus

    This dissertation develops deterministic and stochastic multi-period mixed complementarity problems (MCP) for the global natural gas market, as well as solution approaches for large-scale stochastic MCP. The deterministic model is unique in the combination of the level of detail of the actors in the natural gas markets and the transport options, the detailed regional and global coverage, the multi-period approach with endogenous capacity expansions for transportation and storage infrastructure, the seasonal variation in demand and the representation of market power according to Nash-Cournot theory. The model is applied to several scenarios for the natural gas market that cover the formation of a cartel by the members of the Gas Exporting Countries Forum, a low availability of unconventional gas in the United States, and cost reductions in long-distance gas transportation. 1 The results provide insights in how different regions are affected by various developments, in terms of production, consumption, traded volumes, prices and profits of market participants. The stochastic MCP is developed and applied to a global natural gas market problem with four scenarios for a time horizon until 2050 with nineteen regions and containing 78,768 variables. The scenarios vary in the possibility of a gas market cartel formation and varying depletion rates of gas reserves in the major gas importing regions. Outcomes for hedging decisions of market participants show some significant shifts in the timing and location of infrastructure investments, thereby affecting local market situations. A first application of Benders decomposition (BD) is presented to solve a large-scale stochastic MCP for the global gas market with many hundreds of first-stage capacity expansion variables and market players exerting various levels of market power. The largest problem solved successfully using BD contained 47,373 variables of which 763 first-stage variables, however using BD did not result in

  5. Electromagnetic Field Solutions for the Natural Modes of a Cylindrical Cavity Loaded with Lossy Materials.

    NASA Astrophysics Data System (ADS)

    Manring, Edward Benjamin

    A rigorous solution is presented for the natural mode fields of a circular cylindrical cavity coaxially loaded with homogeneous, isotropic, lossy materials for loads of arbitrary length and distance from the cavity end plates. Field expressions and numerically stable characteristic equations are derived for the coaxially-loaded waveguide, the coaxially-loaded cavity with cavity-length loads (cavity -short type), and the coaxially-loaded cavity with loads of length less than cavity-length (cavity-open type). Cavity -open type solutions are constructed using a mode-matching technique which is shown to be more numerically stable than the mode-matching method previously published for lossless loads. Theoretical and experimental resonant frequency are shown to agree to within 0.2% for a 1" diameter nylon load in a 6" diameter cavity for the cavity-short type configuration and to within 0.06% for all lengths from zero to cavity-length of a 0.5" diameter nylon load in a 6" diameter cavity for the cavity-open type configuration. A solution is included for the azimuthally symmetric TM modes of the cavity-open type configuration for a conducting load; this solution equally applies to the reentrant cavity. Numerical solutions are presented for TE, TM, and hybrid modes of the coaxially-loaded waveguide and the cavity-short type configuration, and the TM modes of the cavity-open type configuration. Complex mode behavior is demonstrated in the waveguide for lossless loads with high dielectric constant. For lossy loads, a backward wave region is discovered in the low frequency range for TM modes. Mode charts presented for the cavity-short type configuration show that mode behavior is highly diverse and that modes cannot be consistently labeled by association with corresponding empty cavity modes which are approached as the load radius becomes small or the dielectric constant approaches unity. Very high loss factor loads are shown to behave like good conductors. It is shown that a

  6. Outcomes of nature of science instruction along a context continuum: preservice secondary science teachers' conceptions and instructional intentions

    NASA Astrophysics Data System (ADS)

    Bell, Randy L.; Mulvey, Bridget K.; Maeng, Jennifer L.

    2016-02-01

    This investigation examined outcomes associated with nature of science (NOS) instruction along a science-content context continuum on the development of secondary preservice science teachers' conceptions of and plans to teach NOS, moving beyond the common dichotomy of contextualized versus noncontextualized instruction. Participants comprised six teacher cohorts (n = 70) enrolled in a two-year Master of Teaching program. Participants were explicitly taught current NOS conceptions using activities that incorporated varied degrees of contextualization and were informed by conceptual change principles during the first program year. Participants' pre- and post-instruction conceptions were assessed using VNOS-C questionnaire written responses and follow-up interviews. Participants' views were classified by degree of alignment (non, partially, or fully aligned) with current NOS conceptions. Interview transcripts were analyzed using analytic induction to verify/refine VNOS responses and to identify patterns in NOS instructional plans and rationales. Wilcoxon signed ranks tests were run to assess possible statistical significance of pre- to post-instruction changes. Participants' responses shifted markedly toward more aligned NOS conceptions post-instruction, with substantial and statistically significant gains for each assessed tenet (all p-values <.001). All participants planned future NOS instruction and most expressed a sophisticated rationale for this choice, including that NOS supported the teaching of key concepts such as evolution. These results indicate that teaching and scaffolding NOS lessons along a context continuum can be effective in eliciting desired changes in preservice teachers' NOS conceptions and instructional intentions within the confines of the science methods course. Future research will examine post-methods course and post-program NOS instruction.

  7. Concepts of Nature and Power: Environmental Ethics of the Northern Ute.

    ERIC Educational Resources Information Center

    Romeo, Stephanie

    1985-01-01

    Describes the approach to resource development of the Northern Ute tribe of Utah. This model preserves the traditional way of life, increases revenues, and minimizes environmental damage. The Ute's historical background and ideology of nature are discussed as well as their fundamental beliefs and moral imperatives associated with natural elements.…

  8. Influence of Teachers' Conceptions of the Nature of Science on Classroom Practice

    ERIC Educational Resources Information Center

    Sarieddine, Diana; BouJaoude, Saouma

    2014-01-01

    Whether teachers' conceptions of NOS are reflected in their instructional planning and classroom practice remains an important research question. Consequently, this study investigated teachers' NOS views and their relationship to their classroom practice and delineated the factors that facilitate or impede this relationship. To achieve this, seven…

  9. Using a Concept Cartoon© Method to Address Elementary School Students' Ideas about Natural Phenomena

    ERIC Educational Resources Information Center

    Minárechová, Michaela

    2016-01-01

    This study investigated the identification and subsequent development or modification of students´ ideas about scientific phenomena by teaching by concept cartoons© method. We found out ideas of students of the fourth grade of primary school by conceptual tasks which were parts of quasi-experiment (pretest and posttest design). For triangulation…

  10. Meaning Making: What Reflective Essays Reveal about Biology Students' Conceptions about Natural Selection

    ERIC Educational Resources Information Center

    Balgopal, Meena M.; Montplaisir, Lisa M.

    2011-01-01

    The process of reflective writing can play a central role in making meaning as learners process new information and connect it to prior knowledge. An examination of the written discourse can therefore be revealing of learners' cognitive understanding and affective (beliefs, feelings, motivation to learn) responses to concepts. Despite reflective…

  11. Effects of radiation damping for biomolecular NMR experiments in solution: a hemisphere concept for water suppression

    PubMed Central

    Ishima, Rieko

    2016-01-01

    Abundant solvent nuclear spins, such as water protons in aqueous solution, cause radiation damping in NMR experiments. It is important to know how the effect of radiation damping appears in high-resolution protein NMR because macromolecular studies always require very high magnetic field strengths with a highly sensitive NMR probe that can easily cause radiation damping. Here, we show the behavior of water magnetization after a pulsed-field gradient (PFG) using nutation experiments at 900 MHz with a cryogenic probe: when water magnetization is located in the upper hemisphere (having +Z component, parallel to the external magnetic field), dephasing of the magnetization by a PFG effectively suppresses residual water magnetization in the transverse plane. In contrast, when magnetization is located in the lower hemisphere (having −Z component), the small residual transverse component remaining after a PFG is still sufficient to induce radiation damping. Based on this observation, we designed 1H-15N HSQC experiments in which water magnetization is maintained in the upper hemisphere, but not necessarily along Z, and compared them with the conventional experiments, in which water magnetization is inverted during the t1 period. The result demonstrates moderate gain of signal-to-noise ratio, 0–28%. Designing the experiments such that water magnetization is maintained in the upper hemisphere allows shorter pulses to be used compared to the complete water flip-back and, thereby, is useful as a building block of protein NMR pulse programs in solution. PMID:27524944

  12. Effects of radiation damping for biomolecular NMR experiments in solution: a hemisphere concept for water suppression.

    PubMed

    Ishima, Rieko

    2015-09-01

    Abundant solvent nuclear spins, such as water protons in aqueous solution, cause radiation damping in NMR experiments. It is important to know how the effect of radiation damping appears in high-resolution protein NMR because macromolecular studies always require very high magnetic field strengths with a highly sensitive NMR probe that can easily cause radiation damping. Here, we show the behavior of water magnetization after a pulsed-field gradient (PFG) using nutation experiments at 900 MHz with a cryogenic probe: when water magnetization is located in the upper hemisphere (having +Z component, parallel to the external magnetic field), dephasing of the magnetization by a PFG effectively suppresses residual water magnetization in the transverse plane. In contrast, when magnetization is located in the lower hemisphere (having -Z component), the small residual transverse component remaining after a PFG is still sufficient to induce radiation damping. Based on this observation, we designed (1)H-(15)N HSQC experiments in which water magnetization is maintained in the upper hemisphere, but not necessarily along Z, and compared them with the conventional experiments, in which water magnetization is inverted during the t1 period. The result demonstrates moderate gain of signal-to-noise ratio, 0-28%. Designing the experiments such that water magnetization is maintained in the upper hemisphere allows shorter pulses to be used compared to the complete water flip-back and, thereby, is useful as a building block of protein NMR pulse programs in solution.

  13. Adsorptive removal of Cd(II) from aqueous solution using natural and modified rice husk.

    PubMed

    Ye, Hengpeng; Zhu, Qing; Du, Dongyun

    2010-07-01

    In this study, the natural and modified rice husk were tested to remove Cd(II) ions from water. The modified rice husk was prepared by being treated with alkali. The results showed the Cd(II) adsorption capacity was 73.96, 125.94 mg/g, respectively, for the natural and modified rice husk. The modified rice husk had faster kinetics and higher adsorption capacities than the natural rice husk, which can be attributed to the surface structural changes of the material. Equilibrium adsorption data are more consistent with the Langmuir isotherm equation than with the Freundlich equation. The Cd(II) adsorption on the two adsorbents tends to increase with the increase of pH. The optimum pH for Cd(II) adsorption is 6.5. Both pseudo-first-order and pseudo-second-order equations were able to describe properly the kinetics of Cd(II) adsorption. The desorbability of Cd(II) is about 95.8-99.1% by 0.1M HCl solution.

  14. Student Knowledge of Scientific and Natural Resource Concepts Concerning Acidic Deposition.

    ERIC Educational Resources Information Center

    Brody, Michael; And Others

    1989-01-01

    Assessed is the level of scientific and natural resource knowledge possessed by fourth-, eighth- and eleventh-grade students. Misconceptions are noted. Discussed are implications for teaching about acidic deposition. (CW)

  15. Assessing explicit and tacit conceptions of the nature of science among preservice elementary teachers

    NASA Astrophysics Data System (ADS)

    Craven, John A., III; Hand, Brian; Prain, Vaughan

    2002-08-01

    This paper reports on the processes and outcomes of practices in a preservice, elementary science methods course designed to: (1) fathom existing student perceptions of the nature of science and (2) move students from holding individually constructed, typically limited views on the nature of science towards more rich, publicly negotiated views. In the course of 15 weeks, 27 preservice elementary students engaged in a series of individual and collaborative exercises that required them to explore their tacit and explicit knowledge about the nature of science. The data were analysed using the interpretative-descriptive approach. Analyses revealed notable, positive changes in the language students used to describe both the nature and structure of the scientific enterprise. The findings of this study support continued efforts in the search for ways of understanding and affecting the views of science that preservice elementary teachers typically hold.

  16. Cell-Mediated Immunity to AAV Vectors, Evolving Concepts and Potential Solutions.

    PubMed

    Basner-Tschakarjan, Etiena; Mingozzi, Federico

    2014-01-01

    Adeno-associated virus (AAV) vectors are one of the most efficient in vivo gene delivery platforms. Over the past decade, clinical trials of AAV vector-mediated gene transfer led to some of the most exciting results in the field of gene therapy and, recently, to the market approval of an AAV-based drug in Europe. With clinical development, however, it became obvious that the host immune system represents an important obstacle to successful gene transfer with AAV vectors. In this review article, we will discuss the issue of cytotoxic T cell responses directed against the AAV capsid encountered on human studies. While over the past several years the field has acquired a tremendous amount of information on the interactions of AAV vectors with the immune system, a lot of questions are still unanswered. Novel concepts are emerging, such as the relationship between the total capsid dose and the T cell-mediated clearance of transduced cells, the potential role of innate immunity in vector immunogenicity highlighted in preclinical studies, and the cross talk between regulatory and effector T cells in the determination of the outcome of gene transfer. There is still a lot to learn about immune responses in AAV gene transfer, for example, it is not well understood what are the determinants of the kinetics of activation of T cells in response to vector administration, why not all subjects develop detrimental T cell responses following gene transfer, and whether the intervention strategies currently in use to block T cell-mediated clearance of transduced cells will be safe and effective for all gene therapy indications. Results from novel preclinical models and clinical studies will help to address these points and to reach the important goal of developing safe and effective gene therapy protocols to treat human diseases.

  17. Natural convection in binary gases driven by combined horizontal thermal and vertical solutal gradients

    NASA Technical Reports Server (NTRS)

    Weaver, J. A.; Viskanta, Raymond

    1992-01-01

    An investigation of natural convection is presented to examine the influence of a horizontal temperature gradient and a concentration gradient occurring from the bottom to the cold wall in a cavity. As the solutal buoyancy force changes from augmenting to opposing the thermal buoyancy force, the fluid motion switches from unicellular to multicellular flow (fluid motion is up the cold wall and down the hot wall for the bottom counterrotating flow cell). Qualitatively, the agreement between predicted streamlines and smoke flow patterns is generally good. In contrast, agreement between measured and predicted temperature and concentration distributions ranges from fair to poor. Part of the discrepancy can be attributed to experimental error. However, there remains considerable discrepancy between data and predictions due to the idealizations of the mathematical model, which examines only first-order physical effects. An unsteady flow, variable thermophysical properties, conjugate effects, species interdiffusion, and radiation were not accounted for in the model.

  18. Solution to Shape Identification of Unsteady Natural Convection Fields to Control Temperature Distribution

    NASA Astrophysics Data System (ADS)

    Katamine, Eiji; Imai, Shinya; Mathmatical design Team; Computational mechanics Team

    2016-11-01

    This paper presents a numerical solution to shape identification of unsteady natural convection fields to control temperature to a prescribed distribution. The square error integral between the actual temperature distributions and the prescribed temperature distributions on the prescribed sub-boundaries during the specified period of time is used as the objective functional. Shape gradient of the shape identification problem is derived theoretically using the Lagrange multiplier method, adjoint variable method, and the formulae of the material derivative. Reshaping is carried out by the traction method proposed as an approach to solving shape optimization problems. Numerical analyses program for the shape identification is developed based on FreeFem++, and the validity of proposed method is confirmed by results of 2D numerical analyses.

  19. Ipomoea dasysperma seed gum: an effective natural coagulant for the decolorization of textile dye solutions.

    PubMed

    Sanghi, Rashmi; Bhattacharya, Bani; Dixit, Awantika; Singh, Vandana

    2006-10-01

    An investigation of dye decolorization from synthetic dye solutions using the non-ionic, water-soluble, high molecular weight seed gums Ipomoea dasysperma and guar gum as coagulants was undertaken. The use of galactomannans derived from plants in this system presents a sustainable method of textile effluent treatment. These natural coagulants extracted from plants proved to be workable alternatives to conventional coagulants like polyaluminum chloride, as they are biodegradable, safe to human health, are cost effective when compared to imported chemicals and have a wider effective dosage range for flocculation of various colloidal suspensions. Coagulant dose and coagulation pH are important factors influencing the mechanism of coagulation. Also the type and chemical structure of the dye plays an important role in the coagulation process. The seed gums alone were found to be effective for decolorization of direct dye and in combination with PAC their coagulation efficiency was well extended even for reactive and acid dyes.

  20. Microbially-Enhanced Redox Solution Reoxidation for Sour Natural Gas Sweetening

    SciTech Connect

    Kenneth Brezinsky

    2008-01-15

    The specific objective of this project are to advance the technology and improve the economics of the commercial iron-based chelate processes such as LO-CAT II and SulFerox process utilizing biologically enhanced reoxidation of the redox solutions used in these processes. The project is based on the use of chelated ferric iron as the catalyst for the production of elemental sulfur, and then oxidizing bacteria, such as Thiobacillus Ferrooxidans (ATCC 23270) as an oxidizer. The regeneration of Fe{sup 3+} - chelate is accomplished by the use of these same microbes under mild conditions at 25-30 C and at atmospheric pressure to minimize the chelate degradation process. The pH of the redox solution was observed to be a key process parameter. Other parameters such as temperature, total iron concentration, gas to liquid ratio and bacterial cell densities also influence the overall process. The second part of this project includes experimental data and a kinetic model of microbial H{sub 2}S removal from sour natural gas using thiobacillus species. In the experimental part, a series of experiments were conducted with a commercial chelated iron catalyst at pH ranges from 8.7 to 9.2 using a total iron concentration range from 925 ppm to 1050 ppm in the solution. Regeneration of the solution was carried out by passing air through the solution. Iron oxidizing bacteria were used at cell densities of 2.3 x 10{sup 7}cells/ml for optimum effective performance. In the modeling part, oxidation of Fe{sup 2+} ions by the iron oxidizing bacteria - Thiobacillus Ferrooxidans was studied for application to a continuous stirred tank reactor (CSTR). The factors that can directly affect the oxidation rate such as dilution rate, temperature, and pH were analyzed. The growth of the microorganism was assumed to follow Monod type of growth kinetics. Dilution rate had influence on the rate of oxidation of ferrous iron. Higher dilution rates caused washout of the biomass. The oxidation rate was

  1. Ammonium removal from aqueous solutions by using natural Chinese (Chende) zeolite as adsorbent.

    PubMed

    Huang, Haiming; Xiao, Xianming; Yan, Bo; Yang, Liping

    2010-03-15

    This paper presents a study of the removal of ammonium ion from aqueous solutions using natural Chinese (Chende) zeolite. A series of experiments was conducted to examine the effects of solution pH, particle size, contact time, adsorbent dosage, and the presence of other cation- and anion species on ammonium removal. The findings indicated that these parameters named had a significant effect on the removal of ammonium by the zeolite. The effect of other cations on the removal of ammonium followed the order of preference Na(+)>K(+)>Ca(2+)>Mg(2+) at identical mass concentrations, and the effect of the presence of individual anions followed the order of preference carbonate>chloride>sulfate>phosphate at identical mass concentrations of ammonium ions. Kinetic analysis showed that the adsorption of ammonium on zeolite at different ranges of particle size well followed the pseudo-second-order model and followed the intra-particle diffusion model only during the initial 60 min of the adsorption process. Equilibrium isotherm data was fitted to the linear Langmuir- and Freundlich models with the latter model providing the better description of the process (R(2)=0.991-0.997) compared to the former (R(2)=0.902-0.989).

  2. Photoproduction of hydrated electrons from natural organic solutes in aquatic environments

    USGS Publications Warehouse

    Zepp, R.G.; Braun, A.M.; Hoigne, J.; Leenheer, J.A.

    1987-01-01

    Laser flash photolysis was used to investigate the transients formed on absorption of 355-nm light by dissolved organic matter (DOM) from natural water bodies and from soil. Absorption spectra and quenching studies of the transients provided confirming evidence that hydrated electrons were formed by all of the DOM that were studied. The DOM from the Suwannee River in Georgia and from the Greifensee, a Swiss lake, exhibited great variability in light-absorbing properties. Despite this high variability in absorption coefficients, the primary quantum yields for electron ejection from the Greifensee and Suwannee DOM fell in a narrow range (0.005-0.008). Steady-state irradiations (355 nm) of the DOM with 2-chloroethanol (0.02 M) present as an electron scavenger produced chloride ions with quantum yields that were about 2 orders of magnitude lower than the primary quantum yields. This result indicates that most of the photoejected electrons recombine with cations before escaping into bulk solution. Irradiations of DOM solutions under sunlight (April, latitude 34?? N) photoproduced electrons at rates falling in the range of 0.2-0.4 ??mol/[(mg of DOC) h]. These results indicate that hydrated electrons can play a significant role in the environmental photoreduction of persistent, electronegative pollutants but may be relatively unimportant in the environmental production of hydrogen peroxide. ?? 1987 American Chemical Society.

  3. Soil engineering in vivo: harnessing natural biogeochemical systems for sustainable, multi-functional engineering solutions

    PubMed Central

    DeJong, Jason T.; Soga, Kenichi; Banwart, Steven A.; Whalley, W. Richard; Ginn, Timothy R.; Nelson, Douglas C.; Mortensen, Brina M.; Martinez, Brian C.; Barkouki, Tammer

    2011-01-01

    Carbon sequestration, infrastructure rehabilitation, brownfields clean-up, hazardous waste disposal, water resources protection and global warming—these twenty-first century challenges can neither be solved by the high-energy consumptive practices that hallmark industry today, nor by minor tweaking or optimization of these processes. A more radical, holistic approach is required to develop the sustainable solutions society needs. Most of the above challenges occur within, are supported on, are enabled by or grown from soil. Soil, contrary to conventional civil engineering thought, is a living system host to multiple simultaneous processes. It is proposed herein that ‘soil engineering in vivo’, wherein the natural capacity of soil as a living ecosystem is used to provide multiple solutions simultaneously, may provide new, innovative, sustainable solutions to some of these great challenges of the twenty-first century. This requires a multi-disciplinary perspective that embraces the science of biology, chemistry and physics and applies this knowledge to provide multi-functional civil and environmental engineering designs for the soil environment. For example, can native soil bacterial species moderate the carbonate cycle in soils to simultaneously solidify liquefiable soil, immobilize reactive heavy metals and sequester carbon—effectively providing civil engineering functionality while clarifying the ground water and removing carbon from the atmosphere? Exploration of these ideas has begun in earnest in recent years. This paper explores the potential, challenges and opportunities of this new field, and highlights one biogeochemical function of soil that has shown promise and is developing rapidly as a new technology. The example is used to propose a generalized approach in which the potential of this new field can be fully realized. PMID:20829246

  4. Soil engineering in vivo: harnessing natural biogeochemical systems for sustainable, multi-functional engineering solutions.

    PubMed

    DeJong, Jason T; Soga, Kenichi; Banwart, Steven A; Whalley, W Richard; Ginn, Timothy R; Nelson, Douglas C; Mortensen, Brina M; Martinez, Brian C; Barkouki, Tammer

    2011-01-06

    Carbon sequestration, infrastructure rehabilitation, brownfields clean-up, hazardous waste disposal, water resources protection and global warming-these twenty-first century challenges can neither be solved by the high-energy consumptive practices that hallmark industry today, nor by minor tweaking or optimization of these processes. A more radical, holistic approach is required to develop the sustainable solutions society needs. Most of the above challenges occur within, are supported on, are enabled by or grown from soil. Soil, contrary to conventional civil engineering thought, is a living system host to multiple simultaneous processes. It is proposed herein that 'soil engineering in vivo', wherein the natural capacity of soil as a living ecosystem is used to provide multiple solutions simultaneously, may provide new, innovative, sustainable solutions to some of these great challenges of the twenty-first century. This requires a multi-disciplinary perspective that embraces the science of biology, chemistry and physics and applies this knowledge to provide multi-functional civil and environmental engineering designs for the soil environment. For example, can native soil bacterial species moderate the carbonate cycle in soils to simultaneously solidify liquefiable soil, immobilize reactive heavy metals and sequester carbon-effectively providing civil engineering functionality while clarifying the ground water and removing carbon from the atmosphere? Exploration of these ideas has begun in earnest in recent years. This paper explores the potential, challenges and opportunities of this new field, and highlights one biogeochemical function of soil that has shown promise and is developing rapidly as a new technology. The example is used to propose a generalized approach in which the potential of this new field can be fully realized.

  5. A study of elementary teachers' conceptions of nature of science and their beliefs about the developmental appropriateness and importance of nature of science throughout a professional development program

    NASA Astrophysics Data System (ADS)

    Adibelli, Elif

    This qualitative study aimed to explore the changes in elementary science teachers' conceptions of nature of science (NOS) and their beliefs about the developmental appropriateness and importance of NOS after participating in an academic, year-long professional development program (PDP) as well as the factors facilitating these changes. The PDP consisted of two phases. In the first phase, the participants received NOS training designed with an explicit-reflective instructional approach. In the second phase, the participants implemented several NOS training activities in their classrooms. Four elementary science teachers who volunteered and completed all components of the PDP (i.e., the NOS training and the NOS teaching) comprised the participants of the present study. A multiple-embedded case study design was employed to explore the changes in the elementary science teachers' conceptions of NOS and their beliefs about the developmental appropriateness and importance of NOS. The study data were collected from multiple sources. The primary data sources included (a) Views of Nature of Science Elementary School Version 2 (VNOS-D2) questionnaire (Lederman & Khishfe, 2002), (b) Ideas about Science for Early Elementary (K-4) Students questionnaire (Sweeney, 2010), and (c) follow-up semi-structured interviews. The secondary data sources included videotaping of meetings with teachers, reflective field notes, and artifacts produced by teachers and their students. Data were analyzed using Yin's (1994, 2003) analytic tactics of pattern matching, explanation building, and cross-case synthesis. The findings of the study revealed that the elementary science teachers showed gradual, but substantial changes in their conceptions, and beliefs about the developmental appropriateness and importance of the NOS aspects over the course of participation in the PDP. Moreover, the participants identified nine components in the PDP that facilitated these changes in their conceptions, and

  6. Nature of science conceptions, attitudes towards evolution and global climate change, and course achievement in an introductory biology course

    NASA Astrophysics Data System (ADS)

    Carter, Benjamin Elijah

    Many researchers have studied student attitudes toward and knowledge of evolutionary science, attitudes towards global climate change (GCC), conceptions about the nature of science (NOS), and course success. However, at the time of this writing, no studies explicitly link these topics. It is overwhelmingly acknowledged by the scientific community that evolution and global climate change (GCC) are undeniably supported by physical evidence. And yet, both topics remain very politically contentious in the United States. Efforts to mitigate the disconnects between the scientific community and the general public on these issues are imperative to science education. Such undertakings need to examine students' conceptions of the nature of science (NOS), how evidence is treated, how theories are constructed, and how scientific consensus is reached, as these may be key factors in acceptance of evolution and GCC. If students have a more thorough understanding of the weight behind scientific consensus and better tools to discern scientific versus non-scientific arguments, they may become more likely to accept strongly supported scientific ideas. Our study explored this hypothesis guided by the following questions: Do changes in NOS conceptions correlate with changes in attitudes towards evolution or GCC? If there are correlations, are they similar for evolution and GCC? What demographic factors affect these correlations? Further, we asked whether attitudes towards evolution before the course began was a significant predictor of achievement in the course. Previously-developed tools were used to measure students' conceptions of the nature of science and attitudes towards evolution, while national public opinion poll questions were used to measure attitudes towards GCC. Demographic questions were produced to target factors thought to influence attitudes towards evolution or global climate change. Overall sample size was N=620. Principle Components Analysis was used to determine

  7. Suppressing Synonymy with a Homonym: The Emergence of the Nomenclatural Type Concept in Nineteenth Century Natural History.

    PubMed

    Witteveen, Joeri

    2016-02-01

    'Type' in biology is a polysemous term. In a landmark article, Paul Farber (Journal of the History of Biology 9(1): 93-119, 1976) argued that this deceptively plain term had acquired three different meanings in early nineteenth century natural history alone. 'Type' was used in relation to three distinct type concepts, each of them associated with a different set of practices. Important as Farber's analysis has been for the historiography of natural history, his account conceals an important dimension of early nineteenth century 'type talk.' Farber's taxonomy of type concepts passes over the fact that certain uses of 'type' began to take on a new meaning in this period. At the closing of the eighteenth century, terms like 'type specimen,' 'type species,' and 'type genus' were universally recognized as referring to typical, model members of their encompassing taxa. But in the course of the nineteenth century, the same terms were co-opted for a different purpose. As part of an effort to drive out nomenclatural synonymy - the confusing state of a taxon being known to different people by different names - these terms started to signify the fixed and potentially atypical name-bearing elements of taxa. A new type concept was born: the nomenclatural type. In this article, I retrace this perplexing nineteenth century shift in meaning of 'type.' I uncover the nomenclatural disorder that the new nomenclatural type concept dissolved, and expose the conceptual confusion it left in its tracks. What emerges is an account of how synonymy was suppressed through the coinage of a homonym.

  8. Characterization of the hydraulics at natural step crests in step-pool streams via weir flow concepts

    NASA Astrophysics Data System (ADS)

    Dust, David; Wohl, Ellen

    2012-09-01

    The hydraulics of step-pool streams are characterized by rapidly varied flow at the step crest, a hydraulic jump, and gradually varied flow in the pool unit of the step-pool sequence. The flow characteristics at the step crests act as the hydraulic control for the water surface profile within the upstream pool unit. Using both field and flume investigations, we demonstrate the use of weir flow concepts for assessing and categorizing the hydraulic characteristics of natural step-crests in step-pool streams. We categorize the results of our investigations in terms of the crest-clast, planform, longitudinal, and instream wood geometries of the step crests. The broad-crested weir equation can be expressed asQ = C* g0.5Wh3/2, where Q is the flowrate, C* is a dimensionless discharge coefficient, W is the crest width, g is the acceleration of gravity, and h is the upstream flow depth above the step crest. Although the flow over a natural step is generally more complex than for an engineered weir, the results of our investigations indicate that the C*-value for simulated and natural steps increases linearly as a function of the upstream head (h), with C* values ranging from 0.15 to 0.97. As a result, the application of weir flow concepts to natural steps provides means for (1) indirectly estimating flow rates; (2) characterizing the hydraulics for individual steps; (3) defining external and/or internal boundary conditions at step crests for hydraulic model simulations of natural or restored step-pool streams; and (4) estimating the upstream pressure force acting on step-crest clasts.

  9. Developing an Evidence-Based Epilepsy Risk Assessment eHealth Solution: From Concept to Market

    PubMed Central

    Shankar, Rohit; Hanna, Jane; McLean, Brendan; Osland, Alex; Milligan, Cathryn; Ball, Abbie; Jory, Caryn; Walker, Matthew

    2016-01-01

    Introduction Sudden unexpected death in epilepsy (SUDEP) is possibly the most common cause of death as a result of complications from epilepsy. The need to educate and regularly review risk for all patients with epilepsy is paramount, but rarely delivered in actual clinical practice. Evidence suggests that education around SUDEP and modifiable risk variables translate into better self-management of epilepsy. Objective We aimed to develop and implement an eHealth solution to support education and self-management of risks, in epilepsy. Methods We undertook an innovation pathways approach, including problem identification, feasibility assessment, design, implementation, and marketing. People with epilepsy were provided a smartphone-based app (Epilepsy Self-Monitor, EpSMon), which translates the clinical risk assessment tool into an educational and self-monitoring platform, for the self-management of epilepsy. Results Results include the success of the marketing campaign, and in what areas, with an estimated reach of approximately 38 million people. EpSMon has proved a success in academic and clinical circles, attracting awards and nominations for awards. The number of users of EpSMon, after 3 months, turned out to be lower than expected (N=221). A 4-month trial of the app in use in the United Kingdom, and the success of the marketing strategy, point to necessary changes to the model of delivery and marketing, summarized in this paper. These include the marketing message, user cost model, and need for the availability of an Android version. Conclusions EpSMon has proven a success in respect to its reception by academics, clinicians, stakeholder groups, and the patients who use it. There is work needed to promote the model and increase its acceptability/attractiveness, including broadening the marketing message, increasing its availability, and reducing its cost. Future development and promotion of the tool will hopefully inform iterative design of its core features for

  10. Pre-Service and In-Service Science Teachers' Conceptions of the Nature of Science

    ERIC Educational Resources Information Center

    Buaraphan, Khajornsak

    2010-01-01

    The author explores the history of nature of science beliefs among pre-service and in-service teachers primarily in the United States and Thailand and compares this history to findings in a current study being conducted in Thailand. Two research questions were used to guide this current study: What are pre-service and in-service science teachers'…

  11. Student Conceptions of Natural Selection and Its Role in Evolution, Research Series No. l65.

    ERIC Educational Resources Information Center

    Bishop, Beth A.; Anderson, Charles W.

    Pretests and posttests on the topic of evolution through natural selection were administered to students in a college nonmajors' biology course. Analysis of test responses revealed that most students understood evolution as a process in which species respond to environmental conditions by changing gradually over time. Student thinking differed…

  12. Learning Nature of Science Concepts through a Research Apprenticeship Program: A Comparative Study of Three Approaches

    ERIC Educational Resources Information Center

    Burgin, Stephen R.; Sadler, Troy D.

    2016-01-01

    The merits of three approaches (explicit, reflective and implicit) to Nature of Science (NOS) teaching and learning in the context of a summer research experience on high school student participants' NOS ideas were explored in this study. The effectiveness of explicit over implicit approaches has been demonstrated in school contexts, but less…

  13. Exploring the Conceptions of a Science Teacher from Karachi about the Nature of Science

    ERIC Educational Resources Information Center

    Shah, Mir Zaman

    2009-01-01

    The main purpose of this study is to investigate a science teacher's beliefs and understanding of the nature of science (NOS) in order to be able to relate these beliefs about the NOS to classroom practice and therefore student experience. Teachers' beliefs about the NOS are embedded in their experiences of learning and teaching science and hence,…

  14. Undergraduate Students' Conceptions of Natural and Anthropogenic Climate Change: A Case Study Approach

    ERIC Educational Resources Information Center

    Trenbath, Thien-Kim Leckie

    2012-01-01

    This dissertation shows the evolution of five undergraduate students' ideas of natural and anthropogenic climate change throughout a lecture hall course on climate change. This research was informed by conceptual change theory and students' inaccurate ideas of climate change. Subjects represented different levels of climate change understanding at…

  15. Political Nature and Socio-Professional Determinants of the Concept of Quality

    ERIC Educational Resources Information Center

    Olaskoaga-Larrauri, Jon; González-Laskibar, Xabier; Barrenetxea-Ayesta, Miren

    2015-01-01

    This paper is based on the hypothesis that the notions of teaching quality used in the higher education sector have a political nature; in other words, they may describe the approaches agents take as regards the duties they perform in institutions of higher education or the model of governance those institutions should adopt. This paper uses the…

  16. Units of nature or processes across scales? The ecosystem concept at age 75.

    PubMed

    Currie, William S

    2011-04-01

    The ecosystem has served as a central organizational concept in ecology for nearly a half century and continues to evolve. As a level in the biotic hierarchy, ecosystems are often viewed as ecological communities integrated with their abiotic environments. This has always been imperfect because of a mismatch of scales between communities and ecosystem processes as they are made operational for field study. Complexity theory has long been forecasted to provide a renewed foundation for ecosystem theory but has been slow to do so. Partly this has arisen from a difficulty in translating theoretical tenets into operational terms for testing in field studies. Ecosystem science has become an important applied science for studying global change and human environmental impacts. Vigorous and important directions in the study of ecosystems today include a growing focus on human-dominated landscapes and development of the concept of ecosystem services for human resource supply and well-being. Today, terrestrial ecosystems are viewed less as well-defined entities or as a level in the biotic hierarchy. Instead, ecosystem processes are being increasingly viewed as the elements in a hierarchy. These occur alongside landscape processes and socioeconomic processes, which combine to form coupled social-ecological systems across a range of scales.

  17. Investigating inquiry beliefs and nature of science (NOS) conceptions of science teachers as revealed through online learning

    NASA Astrophysics Data System (ADS)

    Atar, Hakan Yavuz

    teachers NOS conceptions. Developing desired understanding of nature of science conceptions and having an adequate experience with inquiry learning is especially important for science teachers because science education literature suggests that the development of teachers' nature of science conceptions is influenced by their experiences with inquiry science (Akerson et. al. 2000) and implementation of science lessons reflect teachers' NOS conceptions (Abd-EL-Khalick & Boujaoude, 1997; Matson & Parsons, 1998; Rosenthal, 1993; Trowbridge, Bybee & Powell, 2000; Turner & Sullenger, 1999). Furthermore, the impediments to successful integration of inquiry based science instruction from teachers' perspective are particularly important, as they are the implementers of inquiry based science education reform. The purpose of this study is to understand the relationship between the teachers' NOS conceptions and their inquiry beliefs and practices in their classrooms and how this relationship impedes or contributes to the implementation of inquiry based science education reform efforts. The participants of this study were in-service teachers who were accepted into the online Masters Program in science education program at a southern university. Three online courses offered in the summer semester of 2005 constituted the research setting of this study: (1) Special Problems in the Teaching of Secondary School Science: Nature of Science & Science Teaching, (2) Curriculum in Science Education, and (3) Colloquium. Multiple data sources were used for data triangulation (Miles & Huberman, 1984; Yin, 1994) in order to understand the relationship between participants' NOS views and their conceptions and beliefs about inquiry-based science teaching. The study revealed that the relationship between the teachers' NOS conceptions and their inquiry beliefs and practices is far from being simple and linear. Data suggests that the teachers' sophistication of NOS conceptions influence their perception of

  18. Biological classification historical case studies: Fostering high school students' conceptions of the nature of science

    NASA Astrophysics Data System (ADS)

    Friedman, Ami J.

    The history of science has long been infused in science education. Research conducted in this area has primarily focused on physics and chemistry classes and few studies examine the effects of historical case studies on shaping female students' perspectives of the nature of science. This study aimed to examine female, high school students' conceptualizations of the nature of science while learning biological classification using historical case studies. To meet this end, this study used qualitative methods to identify and explore a female cohort's conceptualizations of the nature of science. Data collection over eight weeks included audio taped individual interviews, audio tapes of lab groups working together, field notes, artifacts, journal entries, a modified VNOS survey, and final exam essays. These data were subjected to qualitative analysis techniques. Initially, younger cohort students, compared with older cohort students, held more limited views of science, whereas the difference between younger and older cohort students dissipated by the end of the unit. Not only did the cohort express a more comprehensive view of science, but they also conceptualized various aspects of science in multiple ways indicating that grade level was not an issue when developing complex notions of the nature of science at the high school level. In addition, cohort students demonstrated a deep understanding of the nature of science by providing examples that reached beyond the biological classification unit. One lesson from the unit specifically addressed gender issues and science, allowing students to role play what was like to be a naturalist or a naturalist's wife during the Age of Discovery. This lesson provided insights into how girls conceptualize issues related to gender and science. In particular, girls viewed the perceptions, experiences, and opportunities of female scientists as being different from those of male scientists. Finally, the implications of this study were

  19. Undergraduate students' conceptions of natural and anthropogenic climate change: A case study approach

    NASA Astrophysics Data System (ADS)

    Trenbath, Thien-Kim Leckie

    This dissertation shows the evolution of five undergraduate students' ideas of natural and anthropogenic climate change throughout a lecture hall course on climate change. This research was informed by conceptual change theory and students' inaccurate ideas of climate change. Subjects represented different levels of climate change understanding at the beginning of the course and were selected based on their scores on a climate change questionnaire. The study was designed to research how students' ideas changed throughout the course and compare trajectories of lower and higher achieving students. At the beginning, students had different levels of understanding, but as the semester continued, the lower-performing students progressed more than the higher-performing students. At the end of the course, all students described more ideas than they did at the beginning; however some of these ideas were inconsistent with the professors' instruction. Lower-performing students struggled more than the higher-performing students. Struggles included differentiating climate change and its causes, effects, and consequences from other environmental problems. Students also struggled with the idea that climate change is anthropogenic despite it being natural in the past. In order to understand that climate change is impacted by human forcings in addition to natural forcings, students developed the relationship that climate change is natural and humans are "speeding it up." They took time to integrate this relationship into their prior ideas. Three of the students constructed a definition of climate change that was different than the professor's. Two students defined "climate change" as only the natural aspects of climate change and reserved the anthropogenic changes for the term "global warming". For a third student, "climate change" included damming rivers, eutrophication, frog mutations, ozone depletion, and overfishing, which are environmental ailments but not climate change.

  20. Bovine superfetation by natural conception secondary to an embryo transfer pregnancy.

    PubMed

    Hall, W H

    1987-07-01

    There was only one embryo transferred to the recipient female. There was no chance for natural service to occur from 21 days prior to the transfer of the embryo to 31 days after the transfer of the 7 day old blastocyst. The surrogate female was palpated as being 38 days pregnant 31 days after the transfer of a 7 day old embryo by an experienced professional before being exposed to the natural service sire. The second fetus was of a different sex than the first and was approximately 60 days less mature. All other pregnancies within this well managed herd were accounted for and no other cows calved within the area close to that time. The remaining recipients carried pregnancies to the approximate expected calving date. Conclusion. This case report should support earlier evidence that superfetation in the bovine can and does occur.

  1. Using the history of research on sickle-cell anemia to affect preservice teachers' conceptions of the nature of science

    NASA Astrophysics Data System (ADS)

    Howe, Eric M.

    Preservice elementary teachers enrolled in an elective biology course participated in an eight-class unit of instruction based on the history of research in understanding the disease sickle-cell anemia. Students were introduced to the disease as a "mystery" for them to solve, and subsequently developed an understanding of the disease from several disciplines in biology (e.g., genetics, ecology, evolution, molecular biology). The unit involved open-ended problems in which students examined evidence and developed explanations in a manner analogous to the reasoning used by Anthony C. Allison and his colleagues during the early to middle part of the twentieth century. Throughout the unit, students were challenged to explicitly and reflectively connect their work with the historical material to more general conclusions about aspects of the nature of science. These aspects included (a) the nature of scientific theories, (b) the tentative nature of science, (c) the difference between scientific theories and laws, (d) the validity of observational methods in science, and (e) the subjective (theory-laden) nature of science. The research measured students' pre- and post-instruction views by using both an open-ended survey (VNOS) and follow-up, semi-structured interviews. The results indicated that an appreciable number of students underwent a change or enrichment in their views for some of the nature of science aspects. Moreover, change or enrichment in students' views was directly attributable to their work in the sickle-cell unit as evidenced from the specific examples students articulated in their post-instruction responses in support of their more informed views. In general, the findings of this research lend empirical support to the value of having students actively recapitulate the history of science to improve their nature of science conceptions. This is facilitated when the lessons challenge students to explicitly and reflectively develop views of the nature of

  2. Restoring native fish assemblages to a regulated California stream using the natural flow regime concept.

    PubMed

    Kiernan, Joseph D; Moyle, Peter B; Crain, Patrick K

    2012-07-01

    We examined the response of fishes to establishment of a new flow regime in lower Putah Creek, a regulated stream in California, U.S.A. The new flow regime was designed to mimic the seasonal timing of natural increases and decreases in stream flow. We monitored fish assemblages annually at six sample sites distributed over approximately 30 km of stream for eight years before and nine years after the new flow regime was implemented. Our purpose was to determine whether more natural stream flow patterns would reestablish native fishes and reduce the abundances of alien (nonnative) fishes. At the onset of our study, native fishes were constrained to habitat immediately (<1 km) below the diversion dam, and alien species were numerically dominant at all downstream sample sites. Following implementation of the new flow regime, native fishes regained dominance across more than 20 km of lower Putah Creek. We propose that the expansion of native fishes was facilitated by creation of favorable spawning and rearing conditions (e.g., elevated springtime flows), cooler water temperatures, maintenance of lotic (flowing) conditions over the length of the creek, and displacement of alien species by naturally occurring high-discharge events. Importantly, restoration of native fishes was achieved by manipulating stream flows at biologically important times of the year and only required a small increase in the total volume of water delivered downstream (i.e., water that was not diverted for other uses) during most water years. Our results validate that natural flow regimes can be used to effectively manipulate and manage fish assemblages in regulated rivers.

  3. Evaluation of unsupervised semantic mapping of natural language with Leximancer concept mapping.

    PubMed

    Smith, Andrew E; Humphreys, Michael S

    2006-05-01

    The Leximancer system is a relatively new method for transforming lexical co-occurrence information from natural language into semantic patterns in a nunsupervised manner. It employs two stages of co-occurrence information extraction-semantic and relational-using a different algorithm for each stage. The algorithms used are statistical, but they employ nonlinear dynamics and machine learning. This article is an attempt to validate the output of Leximancer, using a set of evaluation criteria taken from content analysis that are appropriate for knowledge discovery tasks.

  4. Adsorption of sulfur dioxide on natural clinoptilolite chemically modified with salt solutions.

    PubMed

    Ivanova, Emilia; Koumanova, Bogdana

    2009-08-15

    Various ion exchange forms of preliminary partly decationised zeolite (hydrogen forms) were obtained by indirect modification with metal salt solutions, as well as by direct treatment of natural clinoptilolite taken from Bulgarian deposits. Direct modification leads to a higher extent of samples enrichment with corresponding ion. Independently of the conditions, the alkaline and alkaline earth metal ions (especially sodium and calcium) were inserted at a greater extent, while the transitional metals-at a comparatively lower extent. The cationic forms of clinoptilolite were used for adsorption and desorption experiments. The breakthrough adsorption curves and the concentration curves at temperature-programmed desorption were obtained and compared. The breakthrough and saturation times, the adsorption capacity, the distribution coefficient, the adsorbed SO(2), the portions desorbed as SO(2) and SO(3), respectively, as well as the not desorbed portion of SO(2), were determined using these curves. It was established that a definite quantity of undesorbed SO(2) has remained in the zeolite forms modified with transitional metal cations. This statement was proved not only by the comparison between the adsorbed and desorbed quantities, but also by three-cycle adsorption-desorption experiments for the Cu(2+)-form. The results demonstrate a decrease in the capacity for each following cycle in an extent similar to the undesorbed SO(2) quantity. It was not observed a visible difference in the values of the distribution coefficients for adsorption on identical cation forms, directly or indirectly obtained. However, the breakthrough time of the samples obtained by ion exchange of the hydrogen form was longer in all cases. Definite quantities of desorbed SO(3) were registered for all forms, except for the natural clinoptilolite and the samples enriched with alkaline and alkaline earth metal cations.

  5. USING POPULATION GENOMICS TO DETECT SELECTION IN NATURAL POPULATIONS: KEY CONCEPTS AND METHODOLOGICAL CONSIDERATIONS

    PubMed Central

    Hohenlohe, Paul A.; Phillips, Patrick C.; Cresko, William A.

    2010-01-01

    Natural selection shapes patterns of genetic variation among individuals, populations, and species, and it does so differentially across genomes. The field of population genomics provides a comprehensive genome-scale view of the action of selection, even beyond traditional model organisms. However, even with nearly complete genomic sequence information, our ability to detect the signature of selection on specific genomic regions depends on choosing experimental and analytical tools appropriate to the biological situation. For example, processes that occur at different timescales, such as sorting of standing genetic variation, mutation-selection balance, or fixed interspecific divergence, have different consequences for genomic patterns of variation. Inappropriate experimental or analytical approaches may fail to detect even strong selection or falsely identify a signature of selection. Here we outline the conceptual framework of population genomics, relate genomic patterns of variation to evolutionary processes, and identify major biological factors to be considered in studies of selection. As data-gathering technology continues to advance, our ability to understand selection in natural populations will be limited more by conceptual and analytical weaknesses than by the amount of molecular data. Our aim is to bring critical biological considerations to the fore in population genomics research and to spur the development and application of analytical tools appropriate to diverse biological systems. PMID:21218185

  6. A new concept of hybrid photovoltaic thermal (PVT) collector with natural circulation

    NASA Astrophysics Data System (ADS)

    Lu, Longsheng; Wang, Xiaowu; Wang, Shuai; Liu, Xiaokang

    2017-02-01

    Hybrid photovoltaic thermal (PVT) technology refers to the integration of a photovoltaic module into a conventional solar thermal collector. Generally, the traditional design of a PVT collector has solar cells fixed on the top surface of an absorber in a flat-plate solar thermal collector. In this work, we presented a new concept of water-based PVT collector in which solar cells were directly placed on the bottom surface of its glass cover. A dynamic numerical model of this new PVT is developed and validated by experimental tests. With numerical analysis, it is found that at same covering factor, the electricity conversion efficiency of solar cells of the new PVT exceed that of the traditional PVT by nearly 10% while its thermal efficiency is approximately 30% lower than that of the traditional PVT. When the covering factor changes from 0.05 to 1, the thermal efficiency of the new PVT drops nearly 70%. The thermal efficiency of both the new PVT and the traditional PVT rise up as the water mass in tank increases. Meanwhile, the final water temperature in tank of the traditional PVT collector declines more than 17 °C, whereas that of the new PVT declines less than 6 °C, when the water mass increases from 100 to 300 kg.

  7. Elucidating elementary science teachers' conceptions of the nature of science: A view to beliefs about both science and teaching

    NASA Astrophysics Data System (ADS)

    Keske, Kristina Palmer

    The purpose of this interpretive case study was to elucidate the conceptions of the nature of science held by seven elementary science teachers. The constructivist paradigm provided the philosophical and methodological foundation for the study. Interviews were employed to collect data from the participants about their formal and informal experiences with science. In addition, the participants contributed their perspectives on four aspects of the nature of science: what is science; who is a scientist; what are the methods of science; and how is scientific knowledge constructed. Data analysis not only revealed these teachers' views of science, but also provided insights into how they viewed science teaching. Four themes emerged from the data. The first theme developed around the participants' portrayals of the content of science, with participant views falling on a continuum of limited to universal application of science as procedure. The second theme dealt with the participants' views of the absolute nature of scientific knowledge. Participants' perceptions of the tentative nature of science teaching provided the basis for the third theme concerning the need for absolutes in practice. The fourth theme drew parallels between participants' views of science and science teaching, with two participants demonstrating a consistency in beliefs about knowledge construction across contexts. This study revealed both personal and contextual factors which impacted how the participants saw science and science teaching. Many of the participants' memories of formal science revolved around the memorization of content and were viewed negatively. All the participants had limited formal training in science. Of the seven participants, only two had chosen to be science teachers at the beginning of their careers. The participants' limited formal experiences with science provided little time for exploration into historical, philosophical, and sociological studies of science, a necessary

  8. Munazza's story: Understanding science teaching and conceptions of the nature of science in Pakistan through a life history study

    NASA Astrophysics Data System (ADS)

    Halai, Nelofer

    In this study I have described and tried to comprehend how a female science teacher understands her practice. Additionally, I have developed some understanding of her understanding of the nature of science. While teaching science, a teacher projects messages about the nature of science that can be captured by observations and interviews. Furthermore, the manner is which a teacher conceptualizes science for teaching, at least in part, depends on personal life experiences. Hence, I have used the life history method to understand Munazza's practice. Munazza is a young female science teacher working in a private, co-educational school for children from middle income families in Karachi, Pakistan. Her stories are central to the study, and I have represented them using a number of narrative devices. I have woven in my own stories too, to illustrate my perspective as a researcher. The data includes 13 life history interviews and many informal conversations with Munazza, observations of science teaching in classes seven and eight, and interviews with other science teachers and administrative staff of the school. Munazza's personal biography and experiences of school and undergraduate courses has influenced the way she teaches. It has also influenced the way she does not teach. She was not inspired by her science teachers, so she has tried not to teach the way she was taught science. Contextual factors, her conception of preparation for teaching as preparation for subject content and the tension that she faces in balancing care and control in her classroom are some factors that influence her teaching. Munazza believes that science is a stable, superior and value-free way of knowing. In trying to understand the natural world, observations come first, which give reliable information about the world leading inductively to a "theory". Hence, she relies a great deal on demonstrations in the class where students "see" for themselves and abstract the scientific concept from the

  9. Ammonium sorption from aqueous solutions by the natural zeolite Transcarpathian clinoptilolite studied under dynamic conditions.

    PubMed

    Sprynskyy, Myroslav; Lebedynets, Mariya; Terzyk, Artur P; Kowalczyk, Piotr; Namieśnik, Jacek; Buszewski, Bogusław

    2005-04-15

    The scope of this study is ammonium-ion uptake from synthetic aqueous solutions onto raw and pretreated forms of the natural zeolite Transcarpathian clinoptilolite under dynamic conditions. Hydrogen ions displaced exchangeable cations on the clinoptilolite in distilled water (sodium ions) and hydrochloric acid (sodium, potassium, and calcium ions) and destroyed the zeolite framework structure in the last case. Ammonium uptake onto the zeolite occurs by exchange with Na(+), Ca(2+), and K(+) ions. Although Na(+) ions were observed to be more easily exchanged for both hydrogen and ammonium ions, the role of Ca(2+) ions increased with zeolite saturation by NH(+)(4) ions. The maximum sorption capacity of the clinoptilolite toward NH(+)(4) ions, estimated under dynamic conditions, is significantly higher than that measured under static conditions; proximity of the values of a distribution coefficient and a retardation factor for different conditions (215-265 dm(3)/kg and 979-1107, respectively) allows us to use these parameters to model ammonium uptake onto the clinoptilolite. Slowing down or interruption in filtration resulted in the improvement of ammonium sorption properties of the zeolite. The ammonium removal improves with use of the finer fractions of the clinoptilolite up to 0.35 mm. A recycling study results confirmed the importance of external diffusion for ammonium sorption by the clinoptilolite. Preliminary treatment of the sorbent confirmed the predominant importance of the ion-exchange mechanism. The advantage of prior NaCl treatment of the clinoptilolite in improvement of ammonium removal over the other techniques was shown.

  10. The removal of heavy metals from aqueous solution using natural Jordanian zeolite

    NASA Astrophysics Data System (ADS)

    Taamneh, Yazan; Sharadqah, Suhail

    2016-02-01

    In this article, the adsorption process of cadmium and copper using natural Jordanian (NJ) zeolite as adsorbent has been experimentally estimated. The samples of NJ zeolite were obtained from Al Mafraq discrete, north east of Jordan. The influence of the bulk concentration (C o), contact time (t) and different adsorbent masses (m) of NJ zeolite on the removal of heavy metal were evaluated. These variables had a considerable function in promoting the sorption process of heavy metal using the NJ zeolite. The initial concentration of heavy metals in the stock solution was extended between 80 and 600 mg/L. The batch adsorption method was employed to investigate the adsorption process. The experimental data were correlated using Freundlich and Langmuir empirical formula. The ability of NJ zeolite to eliminate cadmium and copper was estimated according to Langmuir isotherm empirical formula and found 25.9 and 14.3 mg/g for cadmium and copper, respectively. The kinetics of adsorption of cadmium and copper have been analyzed and correlated by first-order and second-order reaction model. It was noticed that adsorption of cadmium and copper was better correlated with pseudo-second-order kinetic model. The results presented that NJ zeolite is practical adsorbent for removing cadmium and copper ion metal.

  11. Marginal cost of natural gas in developing countries: concepts and applications

    SciTech Connect

    Mashayekhi, A.

    1983-01-01

    Many developing nations are facing complex questions regarding the best strategy for developing their domestic gas reserves. The World Bank has addressed these questions in studies on the cost and prices of gas and its optimal allocation among different markets. Based on the average incremental method, an estimate of the marginal cost of natural gas in 10 developing countries proved to be $0.61-1.79/1000 CF or $3.59-10.54/bbl of oil equivalent, far below the border prices of competing fuels in these nations. Moreover, the cost of gas is not expected to rise in these countries within the next 20 years while the reserves/production ratios remain high. The sample involves a variety of gas compositions and production conditions among the countries of Bangladesh, Cameroon, Egypt, India, Morocco, Nigeria, Pakistan, Tanzania, Thailand, and Tunisia.

  12. Conception de la nature et manuels de sciences au Quebec, en France et au Senegal

    NASA Astrophysics Data System (ADS)

    Astalos, Monique

    This study examines a view of nature in primary science education at the international level. Currently, in international studies of science programs, this aspect has been rarely considered. A better knowledge of science textbooks would give one a better understanding of the cultural variations between countries, and, would bring more precision to the cultural contexts. The study analyzes a view of nature, particularly the relationships between man and animal found in primary science textbooks in Quebec, France and Senegal. One needs to discern if there are any differences between these countries. The assumptions are based on the primary science textbooks view of nature that essentially takes an anthropocentric view, but with some variations between cultures. This research is primarily exploratory since this phenomena has been studied only minimally. The problem is examined within each country. The types of relationships between man and animal have been identified and the textbooks have been compared with each other. Similarities and differences are then presented between textbooks of the countries under study. This section also includes an interpretation phase of the possible origins of the types of relationships between man and animal in the textbooks concerned. The results enable one to update the different types of relationships between man and animal found in the science textbooks under scrutiny. Nine types of relationships have been identified. They are: (1) naturalistic; (2) ecologistic; (3) humanistic; (4) moralistic; (5) scientific; (6) aesthetic; (7) utilitarian; (8) dominionistic; and (9) negativistic. The absence of certain categories in some textbooks raises questions on the universality of the values suggested by Kellert's typology (1985). The pre-eminence of the "scientific" category suggests a definite relation with this type of textbook, but also with the general anthropocentric trend generally found in science education. The differences found in

  13. New concept in natural history and management of diabetes mellitus in thalassemia major.

    PubMed

    Chatterjee, Ratna; Bajoria, Rekha

    2009-01-01

    Diabetes Mellitus is a major endocrinopathy, which occurs due transfusional haemosiderosis and is found in 20-30% of adult patients with beta-thalassaemia worldwide, accounting for significant morbidity. It is multifactorial with iron loading being the dominant cause and its management poses a clinical challenge. Diabetes in thalassaemia patients is distinct from type 2 diabetes. It is peculiar in many aspects including its pathophysiology and occurs due to insulin resistance as well as islet cell insufficiency. This article reviews the natural history of diabetes in this presentation with emphasis on prevention monitoring and management. Use of MRI techniques may be useful for future monitoring as well as biochemical monitoring to prevent complications of diabetes. Early intervention with intensified chelation may reverse pancreatic function and structural changes as evident from MRI.

  14. The chemical protecting group concept applied in crosslinking of natural tissues with glutaraldehyde acetals.

    PubMed

    Goissis, G; Yoshioka, S A; Braile, D M; Ramirez, V D

    1998-03-01

    This work describes the results of the controlled crosslinking of collagen matrices by glutaraldehyde based on a double protection strategy, glutaraldehyde acetals and lysine protonation due to the acidic conditions of acetal formation. Materials crosslinked by this approach were characterized by thermal stability comparable to those obtained by conventional procedures with mechanical properties expected for bioprosthesis manufacture and with a higher stability toward collagenase hydrolysis. The integrity of the microfibrillar structure was confirmed by optical and scanning electronic microscopy. The results indicate that the glutaraldehyde acetals procedure may be of potential use for the crosslinking of bovine pericardium used in the manufacture of bioprosthetic devices. Advantages may be related to the production of materials with homogeneous crosslinking distributions, associated with better definition in the nature of the chemical link that they introduce, due to a better distribution of glutaraldehyde within the tissue matrix before the crosslinking reaction is allowed to occur. As a result, materials with improved biological and mechanical properties are expected.

  15. Evaluation of strategies for nature-based solutions to drought: a decision support model at the national scale

    NASA Astrophysics Data System (ADS)

    Simpson, Mike; Ives, Matthew; Hall, Jim

    2016-04-01

    There is an increasing body of evidence in support of the use of nature based solutions as a strategy to mitigate drought. Restored or constructed wetlands, grasslands and in some cases forests have been used with success in numerous case studies. Such solutions remain underused in the UK, where they are not considered as part of long-term plans for supply by water companies. An important step is the translation of knowledge on the benefits of nature based solutions at the upland/catchment scale into a model of the impact of these solutions on national water resource planning in terms of financial costs, carbon benefits and robustness to drought. Our project, 'A National Scale Model of Green Infrastructure for Water Resources', addresses this issue through development of a model that can show the costs and benefits associated with a broad roll-out of nature based solutions for water supply. We have developed generalised models of both the hydrological effects of various classes and implementations of nature-based approaches and their economic impacts in terms of construction costs, running costs, time to maturity, land use and carbon benefits. Our next step will be to compare this work with our recent evaluation of conventional water infrastructure, allowing a case to be made in financial terms and in terms of security of water supply. By demonstrating the benefits of nature based solutions under multiple possible climate and population scenarios we aim to demonstrate the potential value of using nature based solutions as a component of future long-term water resource plans. Strategies for decision making regarding the selection of nature based and conventional approaches, developed through discussion with government and industry, will be applied to the final model. Our focus is on keeping our work relevant to the requirements of decision-makers involved in conventional water planning. We propose to present the outcomes of our model for the evaluation of nature

  16. Isolation of nonvolatile, organic solutes from natural waters by zeotrophic distillation of water from N,N-dimethylformamide

    SciTech Connect

    Leenheer, J.A.; Brown, P.A.; Stiles, E.A.

    1987-05-01

    Nonvolatile, organic solutes that comprise the dissolved organic carbon (DOC) in saline waters were isolated by removal of the water by distillation from a N,N-dimethylformamide-formic acid-acetonitrile mixture. Salts isolated with the DOC were removed by crystallization of sodium chloride and sodium sulfate from the solvent mixture, removal of silicic acid by acidification and precipitation, removal of boric acid by methylation and volatilization, and removal of phosphate by zinc acetate precipitation. Chemical alteration of the organic solutes was minimized during evaporative concentration steps by careful control of acid concentrations in the solvent mixture and was minimized during drying by conversion of the samples to pyridinium and sodium salts. Recoveries of various hydrophilic organic standards from aqueous salt solutions and recoveries of natural organic solutes from various water samples varied from 60 to 100%. Losses of organic solutes during the isolation procedure were nonselective and related to the number of salt- and precipitate-washing cycles in the procedure.

  17. Isolation of nonvolatile, organic solutes from natural waters by zeotrophic distillation of water from N,N-dimethylformamide

    USGS Publications Warehouse

    Leenheer, J.A.; Brown, P.A.; Stiles, E.A.

    1987-01-01

    Nonvolatile, organic solutes that comprise the dissolved organic carbon (DOC) in saline waters were isolated by removal of the water by distillation from a N,N-dimethylformamideformic acid-acetonitrile mixture. Salts isolated with the DOC were removed by crystallization of sodium chloride and sodium sulfate from the solvent mixture, removal of silicic acid by acidification and precipitation, removal of boric acid by methylation and volatilization, and removal of phosphate by zinc acetate precipitation. Chemical alteration of the organic solutes was minimized during evaporative concentration steps by careful control of acid concentrations in the solvent mixture and was minimized during drying by conversion of the samples to pyridinium and sodium salts. Recoveries of various hydrophilic organic standards from aqueous salt solutions and recoveries of natural organic solutes from various water samples varied from 60 to 100%. Losses of organic solutes during the isolation procedure were nonselective and related to the number of salt- and precipitate-washing cycles in the procedure.

  18. Structure and nature of manganese(II) imidazole complexes in frozen aqueous solutions.

    PubMed

    Un, Sun

    2013-04-01

    A common feature of a large majority of the manganese metalloenzymes, as well as many synthetic biomimetic complexes, is the bonding between the manganese ion and imidazoles. This interaction was studied by examining the nature and structure of manganese(II) imidazole complexes in frozen aqueous solutions using 285 GHz high magnet-field continuous-wave electron paramagnetic resonance (cw-HFEPR) and 95 GHz pulsed electron-nuclear double resonance (ENDOR) and pulsed electron-double resonance detected nuclear magnetic resonance (PELDOR-NMR). The (55)Mn hyperfine coupling and isotropic g values of Mn(II) in frozen imidazole solutions continuously decreased with increasing imidazole concentration. ENDOR and PELDOR-NMR measurements demonstrated that the structural basis for this behavior arose from the imidazole concentration-dependent distribution of three six-coordinate and two four-coordinate species: [Mn(H2O)6](2+), [Mn(imidazole)(H2O)5](2+), [Mn(imidazole)2(H2O)4](2+), [Mn(imidazole)3(H2O)](2+), and [Mn(imidazole)4](2+). The hyperfine and g values of manganese proteins were also fully consistent with this imidazole effect. Density functional theory methods were used to calculate the structures, spin and charge densities, and hyperfine couplings of a number of different manganese imidazole complexes. The use of density functional theory with large exact-exchange admixture calculations gave isotropic (55)Mn hyperfine couplings that were semiquantitative and of predictive value. The results show that the covalency of the Mn-N bonds play an important role in determining not only magnetic spin parameters but also the structure of the metal binding site. The relationship between the isotropic (55)Mn hyperfine value and the number of imidazole ligands provides a quick and easy test for determining whether a protein binds an Mn(II) ion using histidine residues and, if so, how many are involved. Application of this method shows that as much as 40% of the Mn(II) ions in

  19. Multiple Solutions in Natural Convection in an Air Filled Square Enclosure: Fractal Dimension of Attractors

    NASA Astrophysics Data System (ADS)

    Aklouche Benouaguef, S.; Zeghmati, B.; Bouhadef, K.; Daguenet, M.

    In this study, we investigated numerically the transient natural convection in a square cavity with two horizontal adiabatic sides and vertical walls composed of two regions of same size maintained at different temperatures. The flow has been assumed to be laminar and bi-dimensional. The governing equations written in dimensionless form and expressed in terms of stream function and vorticity, have been solved using the Alternating Direction Implicit (ADI) method and the GAUSS elimination method. Calculations were performed for air (Pr = 0.71), with a Rayleigh number varying from 2.5x105 to 3.7x106. We analysed the effect of the Rayleigh number on the route to the chaos of the system. The first transition has been found from steady-state to oscillatory flow and the second is a subharmonic bifurcation as the Rayleigh number is increased further. For sufficiently small Rayleigh numbers, present results show that the flow is characterized by four cells with horizontal and vertical symmetric axes. The attractor bifurcates from a stable fixed point to a limit cycle for a Rayleigh number varying from 2.5x105 to 2.51x105. A limit cycle settles from Ra = 3x105 and persists until Ra = 5x105. At a Rayleigh number of 2.5x105 the temporal evolution of the Nusselt number Nu(t) was stationary. As the Rayleigh number increases, the flow becomes unstable and bifurcates to a time periodic solution at a critical Rayleigh number between 2.5x105 and 2.51x105. After the first HOPF bifurcation at Ra = 2.51x105, the oscillatory flow undergoes several bifurcations and ultimately evolves into a chaotic flow.

  20. Natural vermiculite as an exchanger support for heavy cations in aqueous solution.

    PubMed

    da Fonseca, Maria G; de Oliveira, Michelle M; Arakaki, Luiza N H; Espinola, José G P; Airoldi, Claudio

    2005-05-01

    The natural highly charged lamellar silicate vermiculite was investigated as an exchanger matrix in doubly distilled water solution to exchange magnesium inside the lamella with the heavy cations copper, nickel, cobalt, and lead at the solid/liquid interface. The extension of each exchange reaction was dependent on time of reaction, pH, and cation concentration. The maximum time presented the following order Pb2+ < Ni2+ < Cu2+ < Co2+, which corresponds to 12, 24, 48, and 72 h, respectively. The best performance was observed for nickel, as represented by the exchange capacity Nf, which gave values 0.59, 0.76, 0.84, and 0.93 mmol g(-1) for Pb2+ < Co2+ < Cu2+ < Ni2+, respectively. This capacity is dependent on pH interval variation from 1 to 9, being significantly increased in alkaline condition. The isotherm data were adjusted to a modified Langmuir equation and from the data the spontaneous Gibbs free energy was calculated. Linear correlations were obtained through Gibbs free energy or the maximum capacity against the cationic radius plot, with the lowest values for the largest cation lead. An exponential correlation was also observed for the maximum capacity versus enthalpy of hydration plot, indicating a difficulty of the less hydrated cation, lead, in exchanging with magnesium inside the lamellar space, as suggested by the proposed mechanism. The saturated matrices with cations presented a decrease in interlayer distance in comparison with the original vermiculite, which can be related to the hydrated phases, characteristic for each cation, with a lowest value for lead.

  1. Dimerization of green sensitizing cyanines in solution. A spectroscopic and theoretical study of the bonding nature

    NASA Astrophysics Data System (ADS)

    Baraldi, I.; Caselli, M.; Momicchioli, F.; Ponterini, G.; Vanossi, D.

    2002-01-01

    The bonding nature in cyanine-dye aggregates has been investigated by studying dimerization in solution of 3,3 '-disulfopropyl-4,5,4 ',5 '-dibenzo-9-ethyloxacarbocyanine (D) and three other oxacarbocyanine analogues (E, F, G) used as photographic sensitizers in the green spectral region. Quantitative information on the monomer-dimer equilibrium of dye D in different solvents and of its analogues (E, F, G) in water was obtained by measurement of the absorption spectrum as a function of dye concentration and of temperature. Dimerization was found to be generally driven by enthalpic factors traceable to strong attractive van der Waals interactions between the two large and highly polarizable dye molecules. Entropic contributions to ΔG0 usually favour dissociation but are smaller than the enthalpic ones. The visible absorption spectrum of the dimer consists in a classic two-branched exciton band with a marked splitting ( 1600 cm-1 in water). The experimental observations were the subject of a theoretical study including classical molecular dynamics (MD) and Monte Carlo (MC) calculations of the dimer structure and comparative analysis of monomer and dimer spectra by the CS INDO CI method. Computer simulations led to three similar H-type structures, the most stable of which is characterized by a distance of 4.7 Å between the planes of the chromophores and an endo-endo configuration of the sulfopropyl substituents. The calculated dimer spectrum was clearly interpreted in terms of exciton model but a quantitative agreement with the two-maximum exciton band could be obtained only by assuming substantial deviation of the long molecular axes from parallelism. On the basis of normal coordinate calculations it is suggested that such configurations may occur with a high probability in virtue of twisting vibrational motions of extremely low frequency.

  2. CFD modeling of fluid flow and solute transport in a µXCT scanned natural fracture: Impact of fracture geometry on solute transport

    NASA Astrophysics Data System (ADS)

    Huber, F. M.; Enzmann, F.; Wenka, A.; Dentz, M.; Schaefer, T.

    2010-12-01

    Fluid flow and solute transport through fractures are a key process in both industrial and scientific issues ranging from e.g. geothermal energy production to the disposal of nuclear waste in deep geologic formations. Therefore, a fundamental understanding of the various interdependent processes governing fluid flow and solute transport in fractures over a broad range of length and time scales is of utmost importance. Numerous studies have shown the importance of fracture geometry on flow and solute transport. More recently, significance of so called recirculation zones which are accessible for solutes and colloids through hydrodynamic dispersion and molecular diffusion have been identified [1,2] which can be responsible for pronounced late time solute breakthrough (tailing). Unfortunately, these studies are mostly focused on 2D. Thus, the intention of the prevailing study is to investigate the influence of fracture geometry on solute transport under a broad range of flow conditions (Pe number from 0.1 up to 1000) and as a function of flow direction (that is, reversed flow direction) both in 2D and 3D. We present µXCT measurements with a spatial resolution of 80 µm of a natural single fracture in a diorite drill core from Äspö, Sweden, which serves as direct input for computational mesh generation in order to obtain a realistic 3D model. Besides, a 2D model was produced by projecting the 3D mesh into the x-y-plane to completely exclude the fracture aperture information. Computational fluid dynamic simulations in 2D and 3D have been conducted to study fluid flow and conservative tracer (HTO) transport by means of the finite volume code FLUENT. The natural fracture exhibits a very complex geometry with asperities, rough side walls and a heterogenous aperture distribution. Furthermore, the µXCT data clearly shows that the fracture is not filled with fault gauge material. Simulation results confirm the impact of fracture geometry/roughness on fluid flow causing

  3. New concept of solute distribution around a diffusive crystal-solution interface of a binary Lennard-Jones mixture from the viewpoint of molecular dynamics.

    PubMed

    Maeda, Kouji; Asakuma, Yusuke; Fukui, Keisuke

    2008-01-28

    Directional crystallization from a binary mixture was performed by pseudo-NpT ensemble molecular dynamics. The initial crystal phase having a face-centered-cubic (fcc) structure grew toward the whole cell according to the temperature gradient in the universal cell. The growing crystal phase was not planar even though the solute molecules grew in two-dimensional coordinates because the solvent molecules disturbed the crystallization of the solute molecules at the diffusive crystal-solution interface. This represented the essential phenomenon of solute distribution during crystallization. Consequently, the growing crystal phase still contained solvent molecules having a liquid structure. The time change of the solute composition in the early phase of crystal growth showed an increase in solute composition as the time step proceeded. The resulting solute composition in this early phase was considered at different temperature gradients in the universal cell and it increased as the temperature of the initial crystal-solution interface increased. A new distribution coefficient model was proposed as a function of the difference between the local solute composition and bulk solute composition in the solution around the crystal-solution interface. The impurity-solvent distribution coefficient could be represented by the new model for faster growth of the lower temperature's initial interface. As regards a better distribution coefficient, there was found to be a very dilute solution phase over the crystal phase. The new variable "distribution rate" instead of the ambiguous variable "growth rate" was considered as a function of temperature gradient in the universal cell.

  4. Considering Hans-Georg Gadamer's philosophical hermeneutics as a referent for student understanding of nature-of-science concepts

    NASA Astrophysics Data System (ADS)

    Rashford, Jared M.

    The purpose of this study is to examine philosophical hermeneutics as a referent for student understanding of Nature-of-Science (NOS) concepts. Rather than focus on a prescriptive set of canons used in addressing NOS pedagogy in K-12 schools, this study seeks to explicate a descriptive set of principles based on Hans-Georg Gadamer's theory of interpretation that has the potential for developing dispositions necessary for understanding. Central among these are the concepts of fore-structure, prejudice, temporal distance, and history of effect, all of which constitute part of the whole of the hermeneutic circle as envisaged by Gadamer. As such, Gadamer's hermeneutics is contrasted with Cartesian epistemology and its primacy of method, the Enlightenment's prejudice against prejudice, the modernist/progressive tendency to consider all situations as problems to be solved by relegating all forms of knowledge to techne, and the subjective nature of interpretation inherent in a hermeneutics of suspicion. The implication of such a conceptual analysis for NOS pedagogy is that student understanding is considered not so much as a cognitive outcome dependent on a series of mental functions but rather as an ontological characteristic of Dasein (being-human) that situates learning in the interchange between interpreter and text. In addition, the philosophical foundations implicit in addressing student understanding of NOS found in many curricular reform efforts and pedagogical practices in science education are questioned. Gadamer's hermeneutics affords science education a viable philosophical framework within which to consider student understanding of the development of scientific knowledge and the scientific enterprise.

  5. Improving Students' Understanding of the Connections between the Concepts of Real-Gas Mixtures, Gas Ideal-Solutions, and Perfect-Gas Mixtures

    ERIC Educational Resources Information Center

    Privat, Romain; Jaubert, Jean-Noël; Moine, Edouard

    2016-01-01

    In many textbooks of chemical-engineering thermodynamics, a gas mixture obeying the fundamental law pV[subscript m] = RT is most often called ideal-gas mixture (in some rare cases, the term perfect-gas mixture can be found). These textbooks also define the fundamental concept of ideal solution which in theory, can be applied indifferently to…

  6. Changing Preservice Science Teachers' Views of Nature of Science: Why Some Conceptions May be More Easily Altered than Others

    NASA Astrophysics Data System (ADS)

    Mesci, Gunkut; Schwartz, Renee'S.

    2016-02-01

    The purpose of this study was to assess preservice teachers' views of Nature of Science (NOS), identify aspects that were challenging for conceptual change, and explore reasons why. This study particularly focused on why and how some concepts of NOS may be more easily altered than others. Fourteen preservice science teachers enrolled in a NOS and Science Inquiry course participated in this study. Data were collected by using a pre/post format with the Views of Nature of Science questionnaire (VNOS-270), the Views of Scientific Inquiry questionnaire (VOSI-270), follow-up interviews, and classroom artifacts. The results indicated that most students initially held naïve views about certain aspects of NOS like tentativeness and subjectivity. By the end of the semester, almost all students dramatically improved their understanding about almost all aspects of NOS. However, several students still struggled with certain aspects like the differences between scientific theory and law, tentativeness, and socio-cultural embeddedness. Results suggested that instructional, motivational, and socio-cultural factors may influence if and how students changed their views about targeted NOS aspects. Students thought that classroom activities, discussions, and readings were most helpful to improve their views about NOS. The findings from the research have the potential to translate as practical advice for teachers, science educators, and future researchers.

  7. Dynamics of water solutions of natural polysaccharides by fast field cycling nmr relaxometry

    NASA Astrophysics Data System (ADS)

    Prusova, Alena; Conte, Pellegrino; Kucerik, Jiri; de Pasquale, Claudio; Alonzo, Giuseppe

    2010-05-01

    second hydration shell contains water molecules, also recognized as partly-bound (PBW), which are not directly interacting with the hyaluronan chains but with BW. Finally, water molecules, which dynamics is resembling that of the pure and undisturbed water, are indicated either as a bulk water or free water (FW). As hyaluronan concentration is increased the third FW hydration shell is lost and all water molecules are affected by the presence of hyaluronan molecules. This work showed the great potential of FFC-NMR relaxometry in revealing water nature in polysaccharide solutions and the possibility for future applications on complex biological systems. Acknowledgements A.P. gratefully acknowledges a bilateral Erasmus project between Brno University of Technology and University of Palermo which provided grant sustainment for working in Italy. Ministry of Education of the Czech Republic, project MSM 0021630501 is also acknwledged. This work was partially funded by Ce.R.T.A. s.c.r.l. (Centri Regionali per le Tecnologie Alimentari; Italy). Authors kindly acknowledge Dr. Vladimír Velebný (CPN company, Dolní Dobrouč, Czech Republic) for providing of hyaluronan sample.

  8. The nature of aqueous solutions: insights into multiple facets of chemistry and biochemistry from freezing-point depressions.

    PubMed

    Zavitsas, Andreas A

    2010-05-25

    Contrary to current widely held beliefs, many concentrated aqueous solutions of electrolytes and nonelectrolytes behave ideally. For both, the same simple equation yields mole fractions of water that are equal to the theoretical activities of water. No empirical activity coefficients or ad hoc parameters are needed. Thermodynamic hydration numbers and the number of particles produced per mole of solute are found by searching freezing-point depression measurements, as if asking the water, "How much available water solvent is left and how many solute particles are there?" The results answer questions currently under debate: Do solutes alter the nature of water outside their immediate surroundings? What is the number of ion pairs formed by various electrolytes and what affects extents of their formation? What are some factors that cause precipitation of proteins, latexes, and so forth from aqueous solutions upon addition of other solutes (Hofmeister series)? Which nonelectrolytes form aggregates in water and what are the implications? Why do different solutes affect viscosity differently? How do ion-selective channels in cell membranes function at the molecular level?

  9. Evolution of ion emission yield of alloys with the nature of the solute. 2: Interpretation

    NASA Technical Reports Server (NTRS)

    Blaise, G.; Slodzian, G.

    1977-01-01

    Solid solutions of transition elements in copper, nickel, cobalt, iron, and aluminum matrices were analyzed by observing secondary ion emissions under bombardment with 6.2-keV argon ions. Enchancement of the production of solute-element ions was observed. An ion emission model is proposed according to which the ion yield is governed by the probability of an atom leaving the metal in a preionized state. The energy distribution of the valence electrons of the solute atoms is the bases of the probability calculation.

  10. Development of a model to predict the adsorption of lead from solution on a natural streambed sediment

    USGS Publications Warehouse

    Brown, David Wayne; Hem, John David

    1984-01-01

    Adsorption of solutes by solid mineral surfaces commonly influences the dissolved ionic composition of natural waters. A model based on electrical double-layer theory has been developed which appears to be capable of characterizing the surface chemical behavior of a natural fine-grained sediment containing mostly quartz and feldspar. This variable surface charge-variable surface potential (VSC-VSP) model differs from others in being capable of evaluating more closely the effect of total metal ion activity on the pH-dependent change in electrical potential at the solid surface. The model was tested using 10-4 molar solutions of lead and a silt-size fraction of sediment from the bed of Colma Creek, a small stream in urban northern San Mateo County, California. The average deviation of measured percent adsorption and values calculated from the model was 6.6 adsorption percent from pH 2.0 to pH 7.0.

  11. Improving the integration of recreation management with management of other natural resources by applying concepts of scale from ecology.

    PubMed

    Morse, Wayde C; Hall, Troy E; Kruger, Linda E

    2009-03-01

    In this article, we examine how issues of scale affect the integration of recreation management with the management of other natural resources on public lands. We present two theories used to address scale issues in ecology and explore how they can improve the two most widely applied recreation-planning frameworks. The theory of patch dynamics and hierarchy theory are applied to the recreation opportunity spectrum (ROS) and the limits of acceptable change (LAC) recreation-planning frameworks. These frameworks have been widely adopted internationally, and improving their ability to integrate with other aspects of natural resource management has significant social and conservation implications. We propose that incorporating ecologic criteria and scale concepts into these recreation-planning frameworks will improve the foundation for integrated land management by resolving issues of incongruent boundaries, mismatched scales, and multiple-scale analysis. Specifically, we argue that whereas the spatially explicit process of the ROS facilitates integrated decision making, its lack of ecologic criteria, broad extent, and large patch size decrease its usefulness for integration at finer scales. The LAC provides explicit considerations for weighing competing values, but measurement of recreation disturbances within an LAC analysis is often done at too fine a grain and at too narrow an extent for integration with other recreation and resource concerns. We suggest that planners should perform analysis at multiple scales when making management decisions that involve trade-offs among competing values. The United States Forest Service is used as an example to discuss how resource-management agencies can improve this integration.

  12. Natural solutal convection in magnetic fluids: First-order phase transition aspect

    NASA Astrophysics Data System (ADS)

    Ivanov, Aleksey S.

    2016-10-01

    Concentration stratification of magnetic fluids under the action of external magnetic field can disturb mechanical equilibrium in the system and cause intensive solutal convection. The current paper is devoted to the study of free solutal convection in magnetic fluids undergoing first-order phase transition. Simulation of solutal convection in OpenFOAM package makes it possible to compare numeric results with physical experiment observations. The numeric simulation of convective hydrodynamic flows was carried out in the framework of several theories of first-order phase transition in ferrocolloids. The numerical results are compared with experimental observations in order to choose the theory which predicts most accurately the concentration stratification in magnetic fluids undergoing magneto-controllable first-order phase transition.

  13. Evaluating the potential of multi-purpose nature based solutions in peri-urban landscapes - a preliminary assessment

    NASA Astrophysics Data System (ADS)

    Geris, Josie; Wilkinson, Mark; Stutter, Marc; Guenther, Daniel; Soulsby, Chris

    2016-04-01

    Many communities across the world face the increasing challenge of balancing water quantity and quality protection and improvement with accommodating new growth and urban development. Urbanisation is typically associated with detrimental changes in water quality, sediment delivery, and effects on water storage and flow pathways (e.g. increases in flooding). Current mitigation solutions are typically based on isolated design strategies used at specific small scale sites and for storm water only. More holistic catchment scale approaches are urgently required to effectively manage the amount of water flows and protect the raw water quality in peri-urban landscapes. This project aims to provide a better understanding of the connectivity between natural and managed flow pathways, storage, and biogeochemical processes in the peri-urban landscape to eventually aid a more integrated water quantity and quality control design. For an actively urbanising catchment in NE Scotland we seek to understand the spatio-temporal character of the natural flow pathways and associated water quality, and how these may be used to support the design of nature based solutions during urbanisation. We present preliminary findings from a dense and multiscale monitoring network that includes hydrometric, tracer (stable water isotopes) and water quality (turbidity (sediment), nitrate, phosphate) data during a range of contrasting hydroclimatological conditions and at different stages of the development of urban infrastructure. These demonstrate a highly variable nature, both temporally and spatially, with water quality dynamics out of sync with storm responses and depending on management practices. This highlights potential difficulties for managing water quantity and quality simultaneously at the catchment scale, and suggests that a treatment train approach may be required. Well-designed nature based solutions that tackle both water quantity and quality issues will require adaptability and a

  14. Synthesis of hydrochloric acid solution for total mercury determination in natural waters.

    PubMed

    Patel-Sorrentino, Nathalie; Benaim, Jean-Yves; Cossa, Daniel; Lucas, Yves

    2011-01-01

    Total mercury (Hg(T)) determination requires the addition of concentrated hydrochloric acid solution (≥10 mol L(-1) HCl) in relatively high amounts to preserve the samples and to prepare reagent solutions. A method for the preparation of concentrated HCl with Hg(T) concentration of lower than 5 ng L(-1) is described in this article. It is based on the well-known chemical reaction: 2 NH(4)Cl + H(2)SO(4) → (NH(4))(2)SO(4) + 2 HCl. This method is validated thanks to the US Environmental Protection Agency method 1631 and standard reference materials BCR-579 (mercury in coastal seawater).

  15. Employing inquiry-based computer simulations and embedded scientist videos to teach challenging climate change and nature of science concepts

    NASA Astrophysics Data System (ADS)

    Cohen, Edward Charles

    . The students in the video group had marked improvement compared to the non-video group on questions regarding modeling as a tool for representing objects and processes of science modeling aspects as evident by multiple data sources. The findings from the dissertation have potential impacts on improving Nature of Science (NOS) concepts around modeling by efficiently embedding short authentic scientific videos that can be easily used by many educators. Compared to published assessments by the American Association for the Advancement of Science (AAAS), due to the curriculum interventions both groups scored higher than the average United States middle school student on many NOS and climate content constructs.

  16. Employing Inquiry-Based Computer Simulations and Embedded Scientist Videos To Teach Challenging Climate Change and Nature of Science Concepts

    NASA Astrophysics Data System (ADS)

    Cohen, E.

    2013-12-01

    . The students in the video group had marked improvement compared to the non-video group on questions regarding modeling as a tool for representing objects and processes of science modeling aspects as evident by multiple data sources. The findings from the dissertation have potential impacts on improving Nature of Science (NOS) concepts around modeling by efficiently embedding short authentic scientific videos that can be easily used by many educators. Compared to published assessments by the American Association for the Advancement of Science (AAAS), due to the curriculum interventions both groups scored higher than the average United States middle school student on many NOS and climate content constructs.

  17. A Comparison of Numerical and Analytical Radiative-Transfer Solutions for Plane Albedo in Natural Waters

    EPA Science Inventory

    Several numerical and analytical solutions of the radiative transfer equation (RTE) for plane albedo were compared for solar light reflection by sea water. The study incorporated the simplest case, that being a semi-infinite one-dimensional plane-parallel absorbing and scattering...

  18. ON THE DOUBLE NATURED SOLUTIONS OF THE TWO-TEMPERATURE EXTERNAL SOFT PHOTON COMPTONIZED ACCRETION DISKS

    SciTech Connect

    Meirelles Filho, Cesar

    2009-08-01

    We have analyzed pair production in the innermost region of a two-temperature external soft photon Comptonized accretion disk. We have shown that, if the viscosity parameter is greater than a critical value {alpha}{sub c}, the solution to the disk equation is double valued: one, advection dominated, and the other, radiation dominated. When {alpha} {<=} {alpha}{sub c}, the accretion rate has to satisfy m-dot{sub 1}{<=}m-dot{<=}m-dot{sub c} in order to have two steady-state solutions. It is shown that these critical parameters m-dot{sub 1}, m-dot{sub c} are functions of r, {alpha}, and {theta}{sub e}, and {alpha}{sub c} is a function of r and {theta}{sub e}. Depending on the combination of the parameters, the advection-dominated solution may not be physically consistent. It is also shown that the electronic temperature is maximum at the onset of the thermal instability, from which results this inner region. These solutions are stable against perturbations in the electron temperature and in the density of pairs.

  19. A Comparison of Numerical and Analytical Radiative-Transfer Solutions for Plane Albedo of Natural Waters

    EPA Science Inventory

    Three numerical algorithms were compared to provide a solution of a radiative transfer equation (RTE) for plane albedo (hemispherical reflectance) in semi-infinite one-dimensional plane-parallel layer. Algorithms were based on the invariant imbedding method and two different var...

  20. Natural cork agglomerate employed as an environmentally friendly solution for quiet sandwich composites.

    PubMed

    Sargianis, James; Kim, Hyung-ick; Suhr, Jonghwan

    2012-01-01

    Carbon fiber-synthetic foam core sandwich composites are widely used for many structural applications due to their superior mechanical performance and low weight. Unfortunately these structures typically have very poor acoustic performance. There is increasingly growing demand in mitigating this noise issue in sandwich composite structures. This study shows that marrying carbon fiber composites with natural cork in a sandwich structure provides a synergistic effect yielding a noise-free sandwich composite structure without the sacrifice of mechanical performance or weight. Moreover the cork-core sandwich composites boast a 250% improvement in damping performance, providing increased durability and lifetime operation. Additionally as the world seeks environmentally friendly materials, the harvesting of cork is a natural, renewable process which reduces subsequent carbon footprints. Such a transition from synthetic foam cores to natural cork cores could provide unprecedented improvements in acoustic and vibrational performance in applications such as aircraft cabins or wind turbine blades.

  1. Natural Cork Agglomerate Employed as an Environmentally Friendly Solution for Quiet Sandwich Composites

    PubMed Central

    Sargianis, James; Kim, Hyung-ick; Suhr, Jonghwan

    2012-01-01

    Carbon fiber-synthetic foam core sandwich composites are widely used for many structural applications due to their superior mechanical performance and low weight. Unfortunately these structures typically have very poor acoustic performance. There is increasingly growing demand in mitigating this noise issue in sandwich composite structures. This study shows that marrying carbon fiber composites with natural cork in a sandwich structure provides a synergistic effect yielding a noise-free sandwich composite structure without the sacrifice of mechanical performance or weight. Moreover the cork-core sandwich composites boast a 250% improvement in damping performance, providing increased durability and lifetime operation. Additionally as the world seeks environmentally friendly materials, the harvesting of cork is a natural, renewable process which reduces subsequent carbon footprints. Such a transition from synthetic foam cores to natural cork cores could provide unprecedented improvements in acoustic and vibrational performance in applications such as aircraft cabins or wind turbine blades. PMID:22574250

  2. Bridging the Gap between Preservice Early Childhood Teachers' Cultural Values, Perceptions of Values Held by Scientists, and the Relationships of These Values to Conceptions of Nature of Science

    ERIC Educational Resources Information Center

    Akerson, Valarie L.; Buzzelli, Cary A.; Eastwood, Jennifer L.

    2012-01-01

    This study explored preservice teachers' views of their own cultural values, the cultural values they believed scientists hold, and the relationships of these views to their conceptions of nature of science (NOS). Parallel assignments in a foundations of early childhood education and a science methods course required preservice teachers to explore…

  3. Female and Male Teachers' Pro-Environmental Behaviour, Conceptions and Attitudes Towards Nature and the Environment Do Not Differ: Ecofeminism Put to the Test

    ERIC Educational Resources Information Center

    Mc Ewen, B.; Clément, P.; Gericke, N. M.; Nyberg, E.; Hagman, M.; Landström, J.

    2015-01-01

    Teachers' pro-environmental behaviour, conceptions and attitudes towards nature and the environment were investigated using 47 questions from the BIOHEAD-Citizen questionnaire. The sample included 1,109 pre- and in-service teachers from Sweden and France. Analyses showed only few significant differences between female and male teachers. Forty-one…

  4. Pre-Service Teachers' Developing Conceptions about the Nature and Pedagogy of Mathematical Modeling in the Context of a Mathematical Modeling Course

    ERIC Educational Resources Information Center

    Cetinkaya, Bulent; Kertil, Mahmut; Erbas, Ayhan Kursat; Korkmaz, Himmet; Alacaci, Cengiz; Cakiroglu, Erdinc

    2016-01-01

    Adopting a multitiered design-based research perspective, this study examines pre-service secondary mathematics teachers' developing conceptions about (a) the nature of mathematical modeling in simulations of "real life" problem solving, and (b) pedagogical principles and strategies needed to teach mathematics through modeling. Unlike…

  5. Focusing on the Classical or Contemporary? Chinese Science Teacher Educators' Conceptions of Nature of Science Content to Be Taught to Pre-Service Science Teachers

    ERIC Educational Resources Information Center

    Wan, Zhi Hong; Wong, Siu Ling; Wei, Bing; Zhan, Ying

    2013-01-01

    Drawing from the phenomenographic perspective, an exploratory study investigated Chinese teacher educators' conceptions of teaching Nature of Science (NOS) to pre-service science teachers through semi-structured interviews. Five key dimensions emerged from the data. This paper focuses on the dimension, "NOS content to be taught to pre-service…

  6. On the Nature of Singularities in Cosmological Solutions of Einstein's Equations

    NASA Astrophysics Data System (ADS)

    Isenberg, James

    2014-03-01

    The Hawking-Penrose theorems tell us that cosmological solutions of Einstein's equations are generally singular, in the sense of the incompleteness of causal geodesics (the paths of physical observers). These singularities might be marked by the blowup of curvature and therefore crushing tidal forces, or by the breakdown of physical determinism. Penrose has conjectured (in his ``Strong Cosmic Censorship Conjecture'') that it is generically unbounded curvature that causes singularities, rather than causal breakdown. The verification that BKL behavior (marked by the domination of time derivatives over space derivatives) is generically present in a family of solutions has proven to be a useful tool for studying Strong Cosmic Censorship in that family. We discuss what is known about BKL behavior and Strong Cosmic Censorship in families of solutions defined by varying degrees of isometry, and discuss new results which we believe will extend this knowledge and provide new support for Strong Cosmic Censorship. This research has been supported by the NSF under grant PHY 1306441.

  7. On closing the gap between philosophical concepts and their usage in scientific practice: A lesson from the debate about natural selection as mechanism.

    PubMed

    Matthews, Lucas J

    2016-02-01

    In addition to theorizing about the role and value of mechanisms in scientific explanation or the causal structure of the world, there is a fundamental task of getting straight what a 'mechanism' is in the first place. Broadly, this paper is about the challenge of application: the challenge of aligning one's philosophical account of a scientific concept with the manner in which that concept is actually used in scientific practice. This paper considers a case study of the challenge of application as it pertains to the concept of a mechanism: the debate about whether natural selection is a mechanism. By making clear what is and is not at stake in this debate, this paper considers various strategies for dealing with the challenge of application and makes a case for definitional pluralism about mechanism concepts.

  8. Biosorption of cadmium (II) from aqueous solutions by natural and modified non-living leaves of Posidonia oceanica.

    PubMed

    Meseguer, Víctor F; Ortuño, Juan F; Aguilar, M Isabel; Pinzón-Bedoya, Martha L; Lloréns, Mercedes; Sáez, José; Pérez-Marín, Ana B

    2016-12-01

    Natural, HCl-treated, and formaldehyde-treated non-living leaves of Posidonia oceanica, a marine plant, were investigated as potential biosorbents to remove Cd(2+) from aqueous solutions. The studied biosorbents were characterized by elemental analysis and Fourier transform infrared spectroscopy (FTIR) and it was observed that the adsorption capacity of the biosorbents strongly depended on the pH, increasing as the pH rises. The adsorption process was fast. The adsorption kinetic was analyzed using five kinetic models: pseudo-first order, pseudo-second order, Elovich, intraparticle diffusion, and Bangham models. The adsorption isotherms were analyzed by the Langmuir, Freundlich, Dubinin-Radushkevich, Sips, Redlich-Peterson, and Toth models. The maximum biosorption capacity was attained by the biosorbent treated with HCl (1.11 mmol g(-1)). The distribution equilibrium constant and the Gibbs free energy change were calculated. The effects of the presence of Na(+), K(+), Mg(2+), and Ca(2+) ions in the solution on Cd(2+) uptake were studied. Results indicate that non-living leaves of P. oceanica, natural or treated, can be considered as effective and low-cost biosorbents for the removal of cadmium from aqueous solutions.

  9. Sorption of vanadium (V) onto natural soil colloids under various solution pH and ionic strength conditions.

    PubMed

    Luo, Xiuhua; Yu, Lin; Wang, Changzhao; Yin, Xianqiang; Mosa, Ahmed; Lv, Jialong; Sun, Huimin

    2017-02-01

    Batch sorption kinetics and isothermal characteristics of V(V) were investigated on three natural soil colloids (manual loessial soil colloid (MSC), aeolian sandy soil colloid (ASC), and cultivated loessial soil colloid (CSC)) under various solution pH and ionic strength (IS) conditions. Colloids were characterized by atomic force microscopy (AFM), X-ray diffraction (XRD), and fourier transform infrared spectroscopy (FTIR). AFM micrographs showed CSC with an aggregated shape with larger particle diameter as compared with ASC and MSC. XRD spectra revealed the presence of different minerals in natural soil colloids including biotite, kaolinite, calcite and quartz, which might contribute to sorption process. The sorption ability decreased with increase of colloidal particle size. The sorption was mainly attributed to complexation by active carboxylate and alcohol groups of colloidal components. Sorption kinetics and isotherms of V(V) onto natural soil colloids were best fitted with Pseudo-second-order and Freundlich models. Langmuir model indicated that sorption capacity of MSC and ASC was comparable (285.7 and 238.1 mg g(-1)); however, CSC exhibited the lowest sorption capacity (41.5 mg g(-1)) due to its larger particle diameter and aggregated shape. The maximum V(V) sorption capacity reached plateau values at a solution pH ranged between 5.0 and 9.0 for MSC and ASC, and 6.0-8.0 for CSC. Sorption capacity of V(V) onto natural soil colloids decreased with increasing IS. Based on result of this study we can conclude that sorption of V(V) onto natural soil colloids is pH- and IS-dependent. These findings provide insights on the remediation of vanadium-contaminated soils.

  10. The role of food-security solutions in the protection of natural resources and environment of developing countries.

    PubMed

    Lashgarara, Farhad; Mirdamadi, Seyyed Mehdi; Hosseini, Seyyed Jamal Farajollah; Chizari, Mohammad

    2008-10-01

    The majority of the countries of the world, especially developing countries, face environmental problems. Limitations of basic resources (water and soil) and population growth have been the cause of these environmental problems that countries are confronted with. Developing countries have numerous problems, including destruction of forests, vegetable and animal species, and pollution of the environment. Damage to natural resources and the environment can influence the food-security situation. One of the main millennium development goals (MDGs) is protection of the environment and people's health. This cannot obtained unless there is ensured food security. Food security has been defined as a situation when all people, at all times, have physical and economic access to sufficient, safe, and nutritious food needed to maintain a healthy and active life. At the same time, with ensured food security, we can hope to protect the natural resources and environment. The methodology used is descriptive-analytical, and its main purpose is determining the importance and role of food-security solutions in the reduction of environmental hazards and improvement of natural resources and the environmental situation in developing countries. Therefore, some of the most important food-security solutions that can play an important role in this relation were discussed, including conventional research-based technology, biotechnology, information and communication technologies (ICTs), alternative energy sources, and food irradiation.

  11. The ubiquitous nature of accessory calcite in granitoid rocks: Implications for weathering, solute evolution, and petrogenesis

    USGS Publications Warehouse

    White, A.F.; Schulz, M.S.; Lowenstern, J. B.; Vivit, D.V.; Bullen, T.D.

    2005-01-01

    Calcite is frequently cited as a source of excess Ca, Sr and alkalinity in solutes discharging from silicate terrains yet, no previous effort has been made to assess systematically the overall abundance, composition and petrogenesis of accessory calcite in granitoid rocks. This study addresses this issue by analyzing a worldwide distribution of more than 100 granitoid rocks. Calcite is found to be universally present in a concentration range between 0.028 to 18.8 g kg-1 (mean = 2.52 g kg-1). Calcite occurrences include small to large isolated anhedral grains, fracture and cavity infillings, and sericitized cores of plagioclase. No correlation exists between the amount of calcite present and major rock oxide compositions, including CaO. Ion microprobe analyses of in situ calcite grains indicate relatively low Sr (120 to 660 ppm), negligible Rb and 87Sr/86Sr ratios equal to or higher than those of coexisting plagioclase. Solutes, including Ca and alkalinity produced by batch leaching of the granitoid rocks (5% CO2 in DI water for 75 d at 25??C), are dominated by the dissolution of calcite relative to silicate minerals. The correlation of these parameters with higher calcite concentrations decreases as leachates approach thermodynamic saturation. In longer term column experiments (1.5 yr), reactive calcite becomes exhausted, solute Ca and Sr become controlled by feldspar dissolution and 87Sr/ 86Sr by biotite oxidation. Some accessory calcite in granitoid rocks is related to intrusion into carbonate wall rock or produced by later hydrothermal alteration. However, the ubiquitous occurrence of calcite also suggests formation during late stage (subsolidus) magmatic processes. This conclusion is supported by petrographic observations and 87Sr/86Sr analyses. A review of thermodynamic data indicates that at moderate pressures and reasonable CO2 fugacities, calcite is a stable phase at temperatures of 400 to 700??C. Copyright ?? 2005 Elsevier Ltd.

  12. The nature of the sunspot phenomenon. I - Solutions of the heat transport equation

    NASA Technical Reports Server (NTRS)

    Parker, E. N.

    1974-01-01

    It is pointed out that sunspots represent a disruption in the uniform flow of heat through the convective zone. The basic sunspot structure is, therefore, determined by the energy transport equation. The solutions of this equation for the case of stochastic heat transport are examined. It is concluded that a sunspot is basically a region of enhanced, rather than inhibited, energy transport and emissivity. The heat flow equations are discussed and attention is given to the shallow depth of the sunspot phenomenon. The sunspot is seen as a heat engine of high efficiency which converts most of the heat flux into hydromagnetic waves.

  13. Removal of lead from aqueous solutions by using the natural and Fe(III)-modified zeolite

    NASA Astrophysics Data System (ADS)

    Kragović, Milan; Daković, Aleksandra; Sekulić, Živko; Trgo, Marina; Ugrina, Marin; Perić, Jelena; Gatta, G. Diego

    2012-02-01

    In the present study, the sorption of lead by the natural and Fe(III)-modified zeolite (clinoptilolite) is described. The characterization of the natural zeolite-rich rock and the Fe(III)-modified form was performed by chemical analysis, point of the zero charge (pHpzc), X-ray powder diffraction, applying the Rietveld/RIR method for the quantitative phase analysis, and scanning electron microscopy. The effects of sorbents dose and the initial lead concentrations on its sorption by two sorbents were investigated. For both sorbents, it was determined that at lower initial concentrations of lead, ion exchange of inorganic cations in zeolites with lead, together with uptake of hydrogen dominated, while at higher initial lead concentrations beside these processes, chemisorption of lead occurred. Significantly higher sorption of lead was achieved with Fe(III)-modified zeolite. From sorption isotherms, maximum sorbed amounts of lead, under the applied experimental conditions, were 66 mg/g for the natural and 133 mg/g for Fe(III)-modified zeolite. The best fit of experimental data was achieved with the Freundlich model (R2 ≥ 0.94).

  14. Kinetics and mechanism of the degradation of methyl parathion in aqueous hydrogen sulfide solution: investigation of natural organic matter effects.

    PubMed

    Guo, Xiaofen; Jans, Urs

    2006-02-01

    The kinetics of the transformation of methyl parathion have been investigated in aqueous solution containing reduced sulfur species and small concentrations of natural organic matter (NOM) from different sources such as soil, river, and peat. It was shown that NOM mediates the degradation of methyl parathion in aqueous solutions containing hydrogen sulfide. After evaluating and quantifying the effect of the NOM concentration on the degradation kinetics of methyl parathion in the presence of hydrogen sulfide, it was found that the observed pseudo-first-order reaction rate constants (k(obs)) were proportional to NOM concentrations. The influence of pH on the degradation of methyl parathion in the aqueous solutions containing hydrogen sulfide and NOM has been studied. The rate of degradation of methyl parathion was strongly pH dependent. The results indicate k(obs) with a commercially available humic acid has a maximum value at approximately pH 8.3. Two main reaction mechanisms are identified to dominate the degradation of methyl parathion in aqueous solution containing hydrogen sulfide and NOM based on the products aminomethyl parathion and desmethyl methyl parathion. The two mechanisms are nitro-group reduction and nucleophilic attack at the methoxy-carbon. The reduction of the nitro-group is only observed in the presence of NOM. The results of this study form an important base for the evaluation and interpretation of transformation processes of methyl parathion in the environment.

  15. Prevention of degradation of the natural high potency sweetener (2R,4R)-monatin in mock beverage solutions.

    PubMed

    Storkey, Corin; Pattison, David I; Koehler, Jamie A; Gaspard, Dan S; Evans, Jeff C; Hagestuen, Erik D; Davies, Michael J

    2015-04-15

    Exposure of the naturally-occurring sweetener monatin to light and metal ions results in loss of both parent monatin and total indole (monatin plus monatin lactone/lactam) in mock beverage solutions, with an accompanying decrease in sweetness. In this study potential protective strategies to prevent degradation were investigated. Metal ion chelating resin, or the chelators EDTA and desferrioxamine decreased monatin and indole loss for solutions kept either in darkness or exposed to light. Tannic acid and Chinese bayberry extract both afforded protection, but this did not arise from a light filtering effect. Plastics with defined absorbance characteristics provided protection with this being wavelength dependent; yellow transparent PET plastic was most effective. The contribution of these interventions (metal ion removal/binding; antioxidant; light absorption) was additive, with combinations providing the greatest protective effect against monatin and indole loss. These results indicate that it is possible to minimise monatin degradation by appropriate choices of treatments, additives and container.

  16. True molecular solutions of natural cellulose in the binary ionic liquid-containing solvent mixtures.

    PubMed

    Rein, Dmitry M; Khalfin, Rafail; Szekely, Noemi; Cohen, Yachin

    2014-11-04

    Evidence is presented for the first time of true molecular dissolution of cellulose in binary mixtures of common polar organic solvents with ionic liquid. Cryogenic transmission electron microscopy, small-angle neutron-, X-ray- and static light scattering were used to investigate the structure of cellulose solutions in mixture of dimethyl formamide and 1-ethyl-3-methylimidazolium acetate. Structural information on the dissolved chains (average molecular weight ∼ 5 × 10(4)g/mol; gyration radius ∼ 36 nm, persistence length ∼ 4.5 nm), indicate the absence of significant aggregation of the dissolved chains and the calculated value of the second virial coefficient ∼ 2.45 × 10(-2)mol ml/g(2) indicates that this solvent system is a good solvent for cellulose. More facile dissolution of cellulose could be achieved in solvent mixtures that exhibit the highest electrical conductivity. Highly concentrated cellulose solution in pure ionic liquid (27 wt.%) prepared according to novel method, utilizing the rapid evaporation of a volatile co-solvent in binary solvent mixtures at superheated conditions, shows insignificant cellulose molecular aggregation.

  17. Nature of solute loads in the rivers of the Bengal drainage basin, Bangladesh

    NASA Astrophysics Data System (ADS)

    Datta, Dilip K.; Subramanian, V.

    1997-11-01

    The Bengal drainage basin is geologically one of the youngest and tectonically most active denudation regimes of the world, and encompasses the total lower reaches of the Ganges-Brahmaputra-Meghna (GBM) drainage basin. The GBM river system contributes around 4.5% of the total annual global freshwater flux to the oceans. The solute load of the GBM river system is dominated by the carbonate weathering products of the transport-limited denudation regime. However, in the Meghna basin, which drains a mountainous region, silicate weathering is slightly more predominant, and the solute load tends to be more influenced by the atmospheric contribution. The river system represents about 5% (152×10 6 t yr -1) of the annual global chemical flux to the world's oceans. The chemical denudation rate of the GBM system in the Bengal basin, is one of the world's highest (79-114 t km -2 yr -1), suggesting intensive weathering and erosion in the drainage basin both in Bangladesh as well as in the hinterlands of India and China.

  18. Deproteinized natural rubber film forming polymeric solutions for nicotine transdermal delivery.

    PubMed

    Pichayakorn, Wiwat; Suksaeree, Jirapornchai; Boonme, Prapaporn; Amnuaikit, Thanaporn; Taweepreda, Wirach; Ritthidej, Garnpimol C

    2013-01-01

    Film forming polymeric solutions were prepared from DNRL blended with MC, PVA, or SAG, together with dibutylphthalate or glycerine used as plasticizers. These formulations were easily prepared by simple mixing. In a preliminary step, in situ films were prepared by solvent evaporation in a Petri-dish. Their mechanical and physicochemical properties were determined. The in vitro release and skin permeation of nicotine dissolved in these blended polymers were investigated by a modified Franz diffusion cell. The formulations had a white milky appearance, and were homogeneous and smooth in texture. Their pH was suitable for usage in skin contact. The mechanical property of in situ films depended on the ingredients but all compatible films were in an amorphous phase. The DNRL/PVA was shown to be the most suitable mixture to form completed films. The in vitro release and skin permeation studies demonstrated a biphasic release that provided an initial rapid release followed by a constant release rate that fitted the Higuchi's model. Nicotine loaded DNRL/PVA series were selected for the stability test for 3 months. These formulations needed to be kept at 4°C in tight fitting containers. In conclusion, film forming polymeric solutions could be developed for transdermal nicotine delivery systems.

  19. The impact of solution chemistry of electrolyte on the sorption of pentachlorophenol and phenanthrene by natural hematite nanoparticles.

    PubMed

    Zeng, Fanfeng; He, Yan; Lian, Zhenghua; Xu, Jianming

    2014-01-01

    Hematite nanoparticles (NPs) were studied as a sorbent for hydrophobic organic contaminants (OCs) under natural ambient conditions through specially designed contrasting solution chemistry of electrolyte. Ionizable pentachlorophenol (PCP) and non-ionizable phenanthrene (PHE) were selected as representative OCs. The sorption capacities of PCP and PHE were pH-dependent, and a larger amount of PCP was sorbed at pH values below its pKa (4.75). However, the PHE sorption capacity was higher at relatively high or low pHs (e.g. below 4.0 and above 10.0), possibly due to the larger available surface area of the hematite NPs, caused by the higher values of net charges and charge density. Changes in pH might thus affect the sorption of OCs by hematite NPs, through modification of the surface characteristics of the sorbent and the electronic properties of the sorbate molecules. The influence of different ionic strengths indicated that the amounts of PCP and PHE sorbed by hematite NPs decreased as a concentration function of different types of ions (e.g. Na(+), K(+), Mg(2+) and Ca(2+)), with the underlying mechanism possibly being due to four interactions i.e. hydrogen-bonding, competitive sorption by ions in the ambient solution, screening effects and aggregation effects. The results confirmed that the surface chemistry of hematite NPs, the chemical properties of PCP and PHE, and solution chemistry (e.g. pH and ionic strength) of the electrolyte all played an important role in PCP and PHE sorption by hematite NPs. By comparison of both sorption capacity and ecologic advantages, our results suggested that natural hematite NPs would be more competitive and efficient for PCP and PHE sorption than engineered NPs. This finding increases our knowledge regarding the environmental function of natural NPs (such as hematite NPs) for OC remediation through manipulating their interfacial behavior.

  20. Tunable blood compatibility of polysulfobetaine from controllable molecular-weight dependence of zwitterionic nonfouling nature in aqueous solution.

    PubMed

    Shih, Yu-Ju; Chang, Yung

    2010-11-16

    This work describes a tunable blood compatibility of zwitterionic poly(sulfobetaine methacrylate) (polySBMA) polymers at a wide range of high molecular weights from 50 kDa to 300 kDa controlled with a similar polydispersity via homogeneous free-radical polymerization. The control of molecular weights of polySBMA highly regulates the zwitterionic nonfouling nature to resist the adsorption of plasma proteins, the coagulant of human plasma, and the hemolysis of red blood cells. In this study, the upper critical solution temperatures (UCSTs) and hydrodynamic size of prepared polymers are determined to illustrate the correlations between intermolecular zwitterionic associations and blood compatibility of polySBMA suspension in human blood. The polySBMA exhibited clear shifts of UCSTs in the stimuli-responsive control of solution pH and ionic strength, which were strongly associated with the molecular weights of the prepared polymers. Plasma-protein adsorption onto the polySBMA polymers from single-protein solutions and the complex medium of 100% human plasma were measured by dynamic light scattering to determine the nonfouling stability of polySBMA suspension. It was found that the nonfouling nature as well as hydration capability of polySBMA can be effectively controlled via regulated molecular weights of zwitterionic polymers. This work shows that the polySBMA polymer with an optimized molecular weight of about 135 kDa at physiologic temperature is presented high hydration capability to function the best nonfouling character of anticoagulant activity and antihemolytic activity in human blood. The excellent blood compatibility of zwitterionic polySBMA along with their stimuli-responsive phase behavior in aqueous solution suggests their potential for use in blood-contacting targeted delivery and diagnostic applications.

  1. The characterization of the adsorption of cadmium from aqueous solution using natural fibers treated with nanoparticles

    NASA Astrophysics Data System (ADS)

    Rediske, Nicole M.

    The objective of this research was to characterize natural carbon fibers from coconut husks, both bare and impregnated with metallic nanoparticles, in removing cadmium from aqueous media. The adsorbent load, kinetics, isotherm parameters, removal efficiencies, desorption capacity and possible contaminant removal mechanisms were evaluated. It was found that the fibers treated with metallic nanoparticles performed better than the bare fibers in removing cadmium from water. The ideal conditions were found to be neutral pH with low initial cadmium concentrations. Through the kinetic analyses, the adsorption process was first thought to be pseudo first order with two separate adsorption mechanisms apparent. Upon further analysis, it was seen that the first mechanism does not follow the pseudo first order kinetics model. An increase in calcium and magnesium concentrations was observed as the cadmium concentrations decreases. This increase corresponds with first mechanism. This suggests the cadmium removal in the first mechanism is due to ion exchange. The second mechanism's rate constant was consistently lower than the first mechanisms rate constant by an order of magnitude. This led to the hypothesis that the second mechanism is controlled by van de Waals forces, specifically ion-induced dipole interactions, and physical adsorption. It was also found that the cadmium does not effectively desorb from the wasted fibers in DI water. Keywords: Adsorption; kinetics; pseudo first order; cadmium; metallic nanoparticles; natural fibers; removal efficiencies; ion exchange.

  2. Formulation and solution of the delayed gamma dose rate problem using the concept of effective delayed gamma production cross section

    SciTech Connect

    Liew, S.L.; Ku, L.P.

    1989-06-01

    With appropriate approximations, the delayed gamma dose rate problem can be formulated in terms of the effective delayed gamma production cross section. The coupled neutron-delayed-gamma transport equations then take the same form as the coupled neutron-prompt-gamma transport equations and they can, therefore, be solved directly in the same manner. This eliminates the need for the tedious and error prone flux coupling step in conventional calculations. Mathematical formulation and solution algorithms are derived. The advantages of this method are illustrated by an example of its application in the solution of a practical design problem. 62 refs., 10 figs., 1 tab.

  3. A unifying model for elongational flow of polymer melts and solutions based on the interchain tube pressure concept

    NASA Astrophysics Data System (ADS)

    Wagner, Manfred Hermann; Rolón-Garrido, Víctor Hugo

    2015-04-01

    An extended interchain tube pressure model for polymer melts and concentrated solutions is presented, based on the idea that the pressures exerted by a polymer chain on the walls of an anisotropic confinement are anisotropic (M. Doi and S. F. Edwards, The Theory of Polymer Dynamics, Oxford University Press, New York, 1986). In a tube model with variable tube diameter, chain stretch and tube diameter reduction are related, and at deformation rates larger than the inverse Rouse time τR, the chain is stretched and its confining tube becomes increasingly anisotropic. Tube diameter reduction leads to an interchain pressure in the lateral direction of the tube, which is proportional to the 3rd power of stretch (G. Marrucci and G. Ianniruberto. Macromolecules 37, 3934-3942, 2004). In the extended interchain tube pressure (EIP) model, it is assumed that chain stretch is balanced by interchain tube pressure in the lateral direction, and by a spring force in the longitudinal direction of the tube, which is linear in stretch. The scaling relations established for the relaxation modulus of concentrated solutions of polystyrene in oligomeric styrene (M. H. Wagner, Rheol. Acta 53, 765-777, 2014, M. H. Wagner, J. Non-Newtonian Fluid Mech. http://dx.doi.org/10.1016/j.jnnfm.2014.09.017, 2014) are applied to the solutions of polystyrene (PS) in diethyl phthalate (DEP) investigated by Bhattacharjee et al. (P. K. Bhattacharjee et al., Macromolecules 35, 10131-10148, 2002) and Acharya et al. (M. V. Acharya et al. AIP Conference Proceedings 1027, 391-393, 2008). The scaling relies on the difference ΔTg between the glass-transition temperatures of the melt and the glass-transition temperatures of the solutions. ΔTg can be inferred from the reported zero-shear viscosities, and the BSW spectra of the solutions are obtained from the BSW spectrum of the reference melt with good accuracy. Predictions of the EIP model are compared to the steady-state elongational viscosity data of PS

  4. Cobalt (II) removal from aqueous solutions by natural hemp fibers: Batch and fixed-bed column studies

    NASA Astrophysics Data System (ADS)

    Tofan, Lavinia; Teodosiu, Carmen; Paduraru, Carmen; Wenkert, Rodica

    2013-11-01

    Natural hemp fibers were explored as sorbent for the removal of Co(II) ions from aqueous solutions in batch and dynamic conditions. The batch Co(II) sorption capacity increased up to pH 5, reached the maximum (7.5-7.8 mg/g) over the initial pH of 4.5-5. As the initial concentration of metal ion increased (in the range of 25-200 mg/L), the cobalt uptake was enhanced, but the Co(II) removal efficiency decreased. The batch sorption of Co(II) on the tested hemp follows a pseudo-second order model, which relies on the assumption that the chemisorptions may be the rate-controlling step. The Langmuir model better described the Co(II) sorption process on the natural hemp fibers in comparison with the Freundlich model. This finding complies with the results of fixed-bed studies which emphasize that the optimal solution for describing the behavior of the investigated hemp bed column is provided by the Thomas model. The sorption capacity of the hemp fibers column (15.44 mg/g) performed better than that of the Co(II)-hemp batch system (13.58 mg/g). The possibility to use hemp fibers as an alternative in the Co(II) wastewater treatment should be studied under pilot scale applications, so as to complete the studies concerning the removal efficiencies with technical and economic factors that influence process scale-up.

  5. The direct strip casting concept: A low-cost, high-productivity solution for flat products of all steel grades

    SciTech Connect

    Reichelt, W.; Urlau, U.; Burstroem, E.; Nystroem, R.

    1996-12-31

    The Direct Strip Casting concept is characterized by a high degree of flexibility as regards the types of steel to be cast, at the same time guaranteeing a high production rate and low investment costs. It has been planned to cast strips of all steel grades with a thickness of approx. 10 mm. These strips will not be directly transferred to a cold rolling mill but will undergo two or three hot passes before being wound into a coil. A comparison of the economic feasibility of the DSC process with other near net shape casting processes shows that this process is suitable for small as well as large production rates (up to million tpy/strand) because of the low investment and operating costs. Casting and rolling tests performed in a pilot casting machine and in a casting machine for laboratory purposes show potentially that: the crucial element of the DSC process, the belt caster, is sufficiently stable to attain the required final strip geometry already at the time of casting; the hot shaping envisaged in the DSC concept is sufficient to remove a lack of symmetry that may arise during casting; and the rolling passes envisaged in the DSC concept are necessary and yet at the same time adequate for achieving material properties, for example, sufficiently high r-values for deep drawing grades.

  6. Influences of solution chemistry and polymeric natural organic matter on the removal of aquatic pharmaceutical residuals by nanofiltration.

    PubMed

    Zazouli, Mohammad Ali; Susanto, Heru; Nasseri, Simin; Ulbricht, Mathias

    2009-07-01

    This study demonstrates the removal efficiency and the permeate flux behavior during cross-flow nanofiltration (NF) of aqueous solutions of five pharmaceutically active compounds (PhACs). Cephalexin, tetracycline, acetaminophen, indomethacin and amoxicillin were used as models of PhACs, and alginate was selected as model of natural organic matter (NOM). Two commercial composite NF membranes (SR2 and SR3) with different characteristics were used. The highest rejection was observed for tetracycline, i.e., 75-95% for membrane SR 2 and 95-100% for membrane SR 3, while the rejection was least for acetaminophen (32-36% for SR2 and 52-59% for SR3). As the pH of acetaminophen solution was increased (from 6 to 9) the rejection would increase. Changes of ionic content (from 10 to 20mM) lead to increase (from 89 to 93% for SR 3) or decrease (from 100 to 91% for SR2) of cephalexin rejection depending on the membrane used. The permeate flux would decrease with decreasing the pH solution and increasing ionic strength. The addition of alginate in the feed stream decreased the permeate flux, with lower reduction for SR3, and increased the PhAC rejection except for acetaminophen and amoxicillin. Both size and Donnan exclusions seemed to occur, and the effect of Donnan exclusion was more pronounced for the NF membrane having larger effective pore size (SR2).

  7. Feasibility of Topical Applications of Natural High-Concentration Capsaicinoid Solutions in Patients with Peripheral Neuropathic Pain: A Retrospective Analysis

    PubMed Central

    Mouraux, Andre; Deumens, Ronald; Leerink, Marjolein; le Polain de Waroux, Bernard; Joëlle, Quetin-Leclercq

    2016-01-01

    Background. Capsaicin, one of several capsaicinoid compounds, is a potent TRPV1 agonist. Topical application at high concentration (high concentration, >1%) induces a reversible disappearance of epidermal free nerve endings and is used to treat peripheral neuropathic pain (PNP). While the benefit of low-concentration capsaicin remains controversial, the 8%-capsaicin patch (Qutenza®, 2010, Astellas, Netherlands) has shown its effectiveness. This patch is, however, costly and natural high-concentration capsaicinoid solutions may represent a cheaper alternative to pure capsaicin. Methods. In this retrospective study, 149 patients were screened, 132 were included with a diagnosis of neuropathic pain, and eighty-four were retained in the final analyses (median age: 57.5 years [IQR25–75: 44.7–67.1], male/female: 30/54) with PNP who were treated with topical applications of natural high-concentration capsaicinoid solutions (total number of applications: 137). Indications were postsurgical PNP (85.7%) and nonsurgical PNP (14.3%) (posttraumatic, HIV-related, postherpetic, and radicular PNP). Objectives. To assess the feasibility of topical applications of natural high-concentration capsaicinoid solutions for the treatment of PNP. Results. The median treated area was 250 cm2 [IQR25–75: 144–531]. The median amount of capsaicinoids was 55.1 mg [IQR25–75: 28.7–76.5] per plaster and the median concentration was 172.3 μg/cm2 [IQR25–75: 127.6–255.2]. Most patients had local adverse effects on the day of treatment, such as mild to moderate burning pain and erythema. 13.6–19.4% of the patients experienced severe pain or erythema. Following treatment, 62.5% of patients reported a lower pain intensity or a smaller pain surface, and 35% reported a sustained pain relief lasting for at least 4 weeks. Conclusion. Analgesic topical treatment with natural high-concentration capsaicinoid is feasible and may represent a low cost alternative to alleviate PNP in

  8. Adhesion of bacterial pathogens to soil colloidal particles: influences of cell type, natural organic matter, and solution chemistry.

    PubMed

    Zhao, Wenqiang; Walker, Sharon L; Huang, Qiaoyun; Cai, Peng

    2014-04-15

    Bacterial adhesion to granular soil particles is well studied; however, pathogen interactions with naturally occurring colloidal particles (<2 μm) in soil has not been investigated. This study was developed to identify the interaction mechanisms between model bacterial pathogens and soil colloids as a function of cell type, natural organic matter (NOM), and solution chemistry. Specifically, batch adhesion experiments were conducted using NOM-present, NOM-stripped soil colloids, Streptococcus suis SC05 and Escherichia coli WH09 over a wide range of solution pH (4.0-9.0) and ionic strength (IS, 1-100 mM KCl). Cell characterization techniques, Freundlich isotherm, and Derjaguin-Landau-Verwey-Overbeek (DLVO) theory (sphere-sphere model) were utilized to quantitatively determine the interactions between cells and colloids. The adhesion coefficients (Kf) of S. suis SC05 to NOM-present and NOM-stripped soil colloids were significantly higher than E. coli WH09, respectively. Similarly, Kf values of S. suis SC05 and E. coli WH09 adhesion to NOM-stripped soil colloids were greater than those colloids with NOM-present, respectively, suggesting NOM inhibits bacterial adhesion. Cell adhesion to soil colloids declined with increasing pH and enhanced with rising IS (1-50 mM). Interaction energy calculations indicate these adhesion trends can be explained by DLVO-type forces, with S. suis SC05 and E. coli WH09 being weakly adhered in shallow secondary energy minima via polymer bridging and charge heterogeneity. S. suis SC05 adhesion decreased at higher IS 100 mM, which is attributed to the change of hydrophobic effect and steric repulsion resulted from the greater presence of extracellular polymeric substances (EPS) on S. suis SC05 surface as compared to E. coli WH09. Hence, pathogen adhesion to the colloidal material is determined by a combination of DLVO, charge heterogeneity, hydrophobic and polymer interactions as a function of solution chemistry.

  9. Lead removal from aqueous solution by natural and pretreated clinoptilolite: adsorption equilibrium and kinetics.

    PubMed

    Günay, Ahmet; Arslankaya, Ertan; Tosun, Ismail

    2007-07-19

    Adsorption of Pb(II) ions from aqueous solution onto clinoptilolite has been investigated to evaluate the effects of contact time, initial concentration and pretreatment of clinoptilolite on the removal of Pb(II). Experimental data obtained from batch equilibrium tests have been analyzed by four two-parameter (Freundlich, Langmuir, Temkin and Dubinin-Radushkevich), four three-parameter (Redlich-Peterson, Sips, Toth and Khan) isotherm models, and kinetic models including the pseudo-first order, the pseudo-second order and Elovich equations using nonlinear regression technique. Of the two-parameter isotherms, Temkin isotherm was the best to describe the experimental data. Three-parameter isotherms have higher regression coefficients (>0.99) and lower relative errors (<5%) than two-parameter isotherms. The best fitting isotherm was the Sips followed by Toth and Redlich-Peterson isotherm equations. Maximum experimental adsorption capacity was found to be 80.933 and 122.400 mg/g for raw and pretreated clinoptilolite, respectively, for the initial concentration of 400 mg/L. Kinetic parameters; rate constants, equilibrium adsorption capacities and related coefficients for each kinetic model were evaluated according to relative errors and correlation coefficients. Results of the kinetic studies show that best fitted kinetic models are obtained to be in the order: the pseudo-first order, the pseudo-second order and Elovich equations. Using the thermodynamic equilibrium coefficients, Gibbs free energy of the Pb(II)-clinoptilolite system was evaluated. The negative value of change in Gibbs free energy (DeltaG degrees ) indicates that adsorption of Pb(II) on clinoptilolite is spontaneous.

  10. What Makes an Insight Problem? The Roles of Heuristics, Goal Conception, and Solution Recoding in Knowledge-Lean Problems

    ERIC Educational Resources Information Center

    Chronicle, Edward P.; MacGregor, James N.; Ormerod, Thomas C.

    2004-01-01

    Four experiments investigated transformation problems with insight characteristics. In Experiment 1, performance on a version of the 6-coin problem that had a concrete and visualizable solution followed a hill-climbing heuristic. Experiment 2 demonstrated that the difficulty of a version of the problem that potentially required insight for…

  11. Construct Validity: Choosing the Appropriate Factor Analytic Solution for Developing Subscales on a Self-Concept Instrument.

    ERIC Educational Resources Information Center

    Crocker, Linda; Ahmadi, Behrokh

    The subscales of the How I See Myself Scale were originally established by using a principal components analysis on item scores for a sample of 4,217 elementary school children in grades three to six. A re-analysis of the same data using a common factor solution (using test communalities instead of units in the major diagonal of the correlation…

  12. Solutions for VOC and HAPS control on natural gas fired internal combustion engines

    SciTech Connect

    Marcus, J.Z.; Sleigh, S.; Cotherman, R.

    1996-12-31

    Natural gas fired stationary internal combustion engines (IC engines) emit volatile organic compounds (VOC) and hazardous air pollutants (HAP) as part of their normal operations. VOC and HAP emissions are coming under increased scrutiny with the advent of such Clean Air Act Amendments of 1990 regulations as Title I`s Reasonably Available Control Technology (RACT), Title III`s Maximum Achievable Control Technology (MACT) and Title V`s Operating Permit Program (Title V). In addition, many states are imposing more stringent emission limits on these sources. These emissions may also contribute to the reportable chemicals from the total facility under SARA Title III. Numerous facilities nationwide are interested in reducing these emissions in order to comply with current requirements, to opt out of requirements or to reduce reportable chemicals. This paper will examine the source of these emissions, and discuss combustion control technologies and system operating flexibility, end-of-pipe control technologies, and system tuning opportunities which have the potential to reduce VOC and HAP emissions from IC engines. Data will be presented on potential emission reduction efficiencies achievable using the various control options. 7 refs., 4 tabs.

  13. Technology Solutions Case Study: Improving the Field Performance of Natural Gas Furnaces

    SciTech Connect

    2013-11-01

    The objective of this project is to examine the impact that common installation practices and age-induced equipment degradation may have on the installed performance of natural gas furnaces, as measured by steady-state efficiency and AFUE. PARR identified twelve furnaces of various ages and efficiencies that were operating in residential homes in the Des Moines Iowa metropolitan area and worked with a local HVAC contractor to retrieve them and test them for steady-state efficiency and AFUE in the lab. Prior to removal, system airflow, static pressure, equipment temperature rise, and flue loss measurements were recorded for each furnace. After removal from the field the furnaces were transported to the Gas Technology Institute (GTI) laboratory, where PARR conducted steady-state efficiency and AFUE testing. The test results show that steady-state efficiency in the field was 6.4% lower than that measured for the same furnaces under standard conditions in the lab, which included tuning the furnace input and air flow rate. Comparing AFUE measured under ASHRAE standard conditions with the label value shows no reduction in efficiency for the furnaces in this study over their 15 to 24 years of operation when tuned to standard conditions. Further analysis of the data showed no significant correlation between efficiency change and the age or the rated efficiency of the furnace.

  14. Environmental solutions for the sustainable production of bioactive natural products from the marine sponge Crambe crambe.

    PubMed

    Pérez-López, Paula; Ternon, Eva; González-García, Sara; Genta-Jouve, Grégory; Feijoo, Gumersindo; Thomas, Olivier P; Moreira, Ma Teresa

    2014-03-15

    Crambe crambe is a Mediterranean marine sponge known to produce original natural substances belonging to two families of guanidine alkaloids, namely crambescins and crambescidins, which exhibit cytotoxic and antiviral activities. These compounds are therefore considered as potential anticancer drugs. The present study focuses on the environmental assessment of a novel in vivo process for the production of pure crambescin and crambescidin using sponge specimens cultured in aquarium. The assessment was performed following the ISO 14040 standard and extended from the production of the different mass and energy flows to the system to the growth of the sponge in indoor aquarium and further periodic extraction and purification of the bioactive compounds. According to the results, the two stages that have a remarkable contribution to all impact categories are the purification of the bioactive molecules followed by the maintenance of the sponge culture in the aquarium. Among the involved activities, the production of the chemicals (particularly methanol) together with the electricity requirements (especially due to the aquarium lighting) are responsible for up to 90% of the impact in most of the assessed categories. However, the contributions of other stages to the environmental burdens, such as the collection of sponges, considerably depend on the assumptions made during the inventory stage. The simulation of alternative scenarios has led to propose improvement alternatives that may allow significant reductions ranging from 20% to 70%, mainly thanks to the reduction of electricity requirements as well as the partial reuse of methanol.

  15. Application of natural zeolite for phosphorus and ammonium removal from aqueous solutions.

    PubMed

    Karapinar, Nuray

    2009-10-30

    Removal of both nutrients ammonium and phosphorus by natural zeolite has been studied in lab scale by using a mechanically stirred batch system (1000 ml). Zeolite, a mean particle size of 13 microm, was used as an adsorbent for the removal of ammonium and then as a seed material for the precipitation of calcium phosphate. A relationship was established between the uptake of ammonium by zeolite and the ratio of initial ammonium concentration to zeolite dosage. Ammonium uptake of zeolite was almost completed within initial 5 min of adsorption period. There is no pronounced effect of zeolite and ammonium, neither positive nor negative on the amount of calcium phosphate precipitation. The extent of the precipitation of phosphate increased with rising pH. It was also observed that when the system was allowed to relax at constant pH (i.e. under relatively low super saturations), a certain lag time was noted to elapse at the onset of the precipitation. At the pH 7.2, the amount of initial fast precipitation within 5 min and total precipitation within 120 min were around 34% and 93%, respectively. Precipitation of calcium phosphate on to ammonium-loaded zeolite was achieved at low super saturations (< pH 7.5) through secondary nucleation and crystal growth, leading to an increase in particle size.

  16. Adsorption efficiency of natural materials for low-concentration cesium in solution.

    PubMed

    Miura, A; Kubota, T; Hamada, K; Hitomi, T

    2016-01-01

    In this study, several natural materials were investigated in order to clarify their potential use as cesium (Cs) adsorbents in situ. Four materials--carbonized rice hull, beech sawdust, oak sawdust, and charcoal (Japanese cedar)--which were previously shown to have Cs adsorption capabilities, were examined. Cs adsorption experiments were conducted using different initial Cs and adsorbent concentrations. The physical properties, adsorption isotherms, and adsorption processes were then examined, so as to exploit the Cs adsorption characteristics in the field. Based on these findings, carbonized rice hull and beech sawdust were selected as effective Cs adsorbents. It was found that these materials show continuous and stable Cs adsorption rates for different initial Cs concentrations. The adsorption efficiency of these two adsorption materials in combination was considered, and it was shown that the adsorption isotherms for carbonized rice hull and beech sawdust follow the Freundlich model. Furthermore, the beech sawdust adsorption process exhibited better agreement with the calculated values obtained via the adsorption rate model and the adsorption kinetics model than did the carbonized rice hull adsorption.

  17. DETECTING SELECTION IN NATURAL POPULATIONS: MAKING SENSE OF GENOME SCANS AND TOWARDS ALTERNATIVE SOLUTIONS

    PubMed Central

    Haasl, Ryan J.; Payseur, Bret A.

    2016-01-01

    Genomewide scans for natural selection (GWSS) have become increasingly common over the last 15 years due to increased availability of genome-scale genetic data. Here, we report a representative survey of GWSS from 1999 to present and find that (i) between 1999 and 2009, 35 of 49 (71%) GWSS focused on human, while from 2010 to present, only 38 of 83 (46%) of GWSS focused on human, indicating increased focus on nonmodel organisms; (ii) the large majority of GWSS incorporate interpopulation or interspecific comparisons using, for example FST, cross-population extended haplotype homozygosity or the ratio of nonsynonymous to synonymous substitutions; (iii) most GWSS focus on detection of directional selection rather than other modes such as balancing selection; and (iv) in human GWSS, there is a clear shift after 2004 from microsatellite markers to dense SNP data. A survey of GWSS meant to identify loci positively selected in response to severe hypoxic conditions support an approach to GWSS in which a list of a priori candidate genes based on potential selective pressures are used to filter the list of significant hits a posteriori. We also discuss four frequently ignored determinants of genomic heterogeneity that complicate GWSS: mutation, recombination, selection and the genetic architecture of adaptive traits. We recommend that GWSS methodology should better incorporate aspects of genomewide heterogeneity using empirical estimates of relevant parameters and/or realistic, whole-chromosome simulations to improve interpretation of GWSS results. Finally, we argue that knowledge of potential selective agents improves interpretation of GWSS results and that new methods focused on correlations between environmental variables and genetic variation can help automate this approach. PMID:26224644

  18. Bridging the Gap Between Preservice Early Childhood Teachers' Cultural Values, Perceptions of Values Held by Scientists, and the Relationships of These Values to Conceptions of Nature of Science

    NASA Astrophysics Data System (ADS)

    Akerson, Valarie L.; Buzzelli, Cary A.; Eastwood, Jennifer L.

    2011-07-01

    This study explored preservice teachers' views of their own cultural values, the cultural values they believed scientists hold, and the relationships of these views to their conceptions of nature of science (NOS). Parallel assignments in a foundations of early childhood education and a science methods course required preservice teachers to explore their own cultural backgrounds and their perceptions of the cultural backgrounds of scientists. The Schwartz Values Inventory was used to measure preservice teachers' personal cultural values and those they perceived of scientists. The Views of Nature of Science version B questionnaire and interviews assessed teachers' conceptions of NOS. Copies of student work were collected and sought for themes indicating how preservice teachers perceived scientists' cultural values and how those perceptions changed over time. We found that from the beginning to the end of the semester, preservice teachers perceived fewer differences between their own cultural values and those they perceived scientists held, though they did not change their own cultural values. We found that preservice teachers' NOS conceptions improved, and that they were related to both their cultural values and those they perceived scientists held. Preservice teachers who indicated the fewest differences between their own cultural values and those they perceived scientists held the most informed conceptions of NOS.

  19. Concept-Development of a Structure Supported Membrane for Deployable Space Applications - From Nature to Manufacture and Testing

    NASA Technical Reports Server (NTRS)

    Zander, Martin; Belvin, W. K.

    2012-01-01

    Current space applications of membrane structures include large area solar power arrays, solar sails, antennas, and numerous other large aperture devices like the solar shades of the new James Webb Space Telescope. These expandable structural systems, deployed in-orbit to achieve the desired geometry, are used to collect, reflect and/or transmit electromagnetic radiation. This work, a feasibility study supporting a diploma thesis, describes the systematic process for developing a biologically inspired concept for a structure supported (integrated) membrane, that features a rip stop principle, makes self-deployment possible and is part of an ultra-light weight space application. Novel manufacturing of membrane prototypes and test results are presented for the rip-stop concepts. Test data showed that the new membrane concept has a higher tear resistance than neat film of equivalent mass.

  20. Nature of amine-surfactant interactions at the air-solution interface.

    PubMed

    Penfold, J; Thomas, R K; Zhang, X L; Taylor, D J F

    2009-04-07

    significant in the context of understanding the unusual nature of the PEI/surfactant interaction and of using small molecular weight additives rather than much larger molecular weight polymers to manipulate adsorption properties.

  1. Translation of a solution-based biomineralization concept into a carrier-based delivery system via the use of expanded-pore mesoporous silica

    PubMed Central

    Niu, Li-na; Mao, Jing; Huang, Cui; Pashley, David H.; Tay, Franklin R.

    2016-01-01

    Mineralization of collagen fibrils using solution-based systems containing biomimetic analogs of matrix proteins to stabilize supersaturated calcium phosphate solutions have been predictably achieved in-vitro. Solution-based systems have limitations when used for in-situ remineralization of human hypomineralized tissues because periodic replenishment of the mineralizing solution is infeasible. A carrier-based platform designed for delivering mineral precursors would be highly desirable. In the present work, mesoporous silica nanoparticles with expanded pores (eMSN; 14.8 nm) were synthesized. Polyacrylic acid-stabilized amorphous calcium phosphate (PA-ACP) was generated from a supersaturated calcium and phosphate ion-containing solution, and chosen as the model mineralizing phase. After amine functionalization (AF) of the eMSN through a post-grafting method, the positively-charged AF-eMSN enabled loading of PA-ACP by electrostatic interaction. In-vitro cytotoxicity testing indicated that PA-ACP@AF-eMSN was highly biocompatible. The release kinetics of mineralization precursors from PA-ACP@AF-eMSN was characterized by an initial period of rapid calcium and phosphate release that reached a plateau after 120 hr. Intrafibrillar mineralization was examined using a 2-D fibrillar collagen model; successful mineralization was confirmed using transmission electron microscopy. To date, this is the first endeavor that employs expanded-pore mesoporous silica to deliver polymer-stabilized intermediate precursors of calcium phosphate for intrafibrillar mineralization of collagen. The carrier-based delivery system bridges the gap between contemporary solution-based biomineralization concepts and clinical practice, and is useful for in-situ remineralization of bone and teeth. PMID:26657191

  2. 'That's What Scientists Have To Do': Preservice Elementary Teachers' Conceptions of the Nature of Science during a Moon Investigation.

    ERIC Educational Resources Information Center

    Abell, Sandra; Martini, Mariana; George, Melissa

    2001-01-01

    Describes a science methods course for elementary education majors in which students investigated the phases of the moon. Concludes that students did not make direct connections between their science learning activities and the nature of science. Provides a set of recommendations related to the nature of science and moon study. (Contains 27…

  3. Interactions between Mathematics and Physics: The History of the Concept of Function--Teaching with and about Nature of Mathematics

    ERIC Educational Resources Information Center

    Kjeldsen, Tinne Hoff; Lützen, Jesper

    2015-01-01

    In this paper, we discuss the history of the concept of function and emphasize in particular how problems in physics have led to essential changes in its definition and application in mathematical practices. Euler defined a function as an analytic expression, whereas Dirichlet defined it as a variable that depends in an arbitrary manner on another…

  4. The Online Dissemination of Nature–Health Concepts: Lessons from Sentiment Analysis of Social Media Relating to “Nature-Deficit Disorder”

    PubMed Central

    Palomino, Marco; Taylor, Tim; Göker, Ayse; Isaacs, John; Warber, Sara

    2016-01-01

    Evidence continues to grow supporting the idea that restorative environments, green exercise, and nature-based activities positively impact human health. Nature-deficit disorder, a journalistic term proposed to describe the ill effects of people’s alienation from nature, is not yet formally recognized as a medical diagnosis. However, over the past decade, the phrase has been enthusiastically taken up by some segments of the lay public. Social media, such as Twitter, with its opportunities to gather “big data” related to public opinions, offers a medium for exploring the discourse and dissemination around nature-deficit disorder and other nature–health concepts. In this paper, we report our experience of collecting more than 175,000 tweets, applying sentiment analysis to measure positive, neutral or negative feelings, and preliminarily mapping the impact on dissemination. Sentiment analysis is currently used to investigate the repercussions of events in social networks, scrutinize opinions about products and services, and understand various aspects of the communication in Web-based communities. Based on a comparison of nature-deficit-disorder “hashtags” and more generic nature hashtags, we make recommendations for the better dissemination of public health messages through changes to the framing of messages. We show the potential of Twitter to aid in better understanding the impact of the natural environment on human health and wellbeing. PMID:26797628

  5. Natural laccase mediators separated from water-washed solution of steam exploded corn straw by nanofiltration and organic solvent fractionation.

    PubMed

    Qiu, Weihua; Zhang, Wenyan; Chen, Hongzhang

    2014-03-01

    Artificially synthetic mediators of laccase had the limitation of high cost and possible toxicity. The separation of natural laccase mediators from water-washed solution (WWS) of steam exploded corn straw (SECS) was studied using nano-filtration and successive organic solvents extraction. Results indicated that the UV absorption intensity of nano-filtrated WWS was significantly enhanced. The UV absorption intensity of each extractive from WWS could be ranked as ether extractive (EE)>ethyl acetate extractive (EAE)>chloroform extractive (CE). Decoloration of crystal violet catalyzed by laccase/EE was higher than that by laccase/ABTS, which was 66.95% and 61.9% at 8h, respectively. All the decoloration rates of malachite green at 60min using EE, EAE and ABTS as mediator were both more than 80%. This research would benefit for broaden the source of laccase mediator and reduce the using cost of laccase/mediator system.

  6. Heat stability of strawberry anthocyanins in model solutions containing natural copigments extracted from rose (Rosa damascena Mill.) petals.

    PubMed

    Shikov, Vasil; Kammerer, Dietmar R; Mihalev, Kiril; Mollov, Plamen; Carle, Reinhold

    2008-09-24

    Thermal degradation and color changes of purified strawberry anthocyanins in model solutions were studied upon heating at 85 degrees C by HPLC-DAD analyses and CIELCh measurements, respectively. The anthocyanin half-life values increased significantly due to the addition of rose (Rosa damascena Mill.) petal extracts enriched in natural copigments. Correspondingly, the color stability increased as the total color difference values were smaller for anthocyanins upon copigment addition, especially after extended heating. Furthermore, the stabilizing effect of rose petal polyphenols was compared with that of well-known copigments such as isolated kaempferol, quercetin, and sinapic acid. The purified rose petal extract was found to be a most effective anthocyanin-stabilizing agent at a molar pigment/copigment ratio of 1:2. The results obtained demonstrate that the addition of rose petal polyphenols slows the thermal degradation of strawberry anthocyanins, thus resulting in improved color retention without affecting the gustatory quality of the product.

  7. The effectiveness of solution-focused therapy and short- and long-term psychodynamic psychotherapy on self-concept during a 3-year follow-up.

    PubMed

    Lindfors, Olavi; Knekt, Paul; Virtala, Esa; Laaksonen, Maarit A

    2012-11-01

    This study compares the effectiveness of solution-focused therapy (SFT) and short- and long-term psychodynamic psychotherapy (SPP and LPP) on self-concept during a 3-year follow-up. Altogether, 326 patients with mood or anxiety disorder were randomized to SFT, SPP, and LPP in the Helsinki Psychotherapy Study. Outcome was assessed using the Structural Analysis of Social Behavior questionnaire at baseline and 7, 12, 24, and 36 months after. Overall, during the first year of follow-up, self-concept improved more in both SFT and SPP than in LPP, indicated by the primary outcome indicators self-directed affiliation (AF) and self-directed autonomy, as well as by most of the eight secondary cluster scores. After the 3-year follow-up, LPP was more effective than SFT in AF and in the cluster scores self-affirm, self-blame, and self-neglect, whereas no difference was noted between LPP and SPP. Long duration and psychodynamic orientation of therapy may be beneficial for self-concept improvement.

  8. Photocatalytic degradation of humic substances in aqueous solution using Cu-doped ZnO nanoparticles under natural sunlight irradiation.

    PubMed

    Maleki, Afshin; Safari, Mahdi; Shahmoradi, Behzad; Zandsalimi, Yahya; Daraei, Hiua; Gharibi, Fardin

    2015-11-01

    In this study, Cu-doped ZnO nanoparticles were investigated as an efficient synthesized catalyst for photodegradation of humic substances in aqueous solution under natural sunlight irradiation. Cu-doped ZnO nanocatalyst was prepared through mild hydrothermal method and was characterized using FT-IR, powder XRD and SEM techniques. The effect of operating parameters such as doping ratio, initial pH, catalyst dosage, initial concentrations of humic substances and sunlight illuminance were studied on humic substances degradation efficiency. The results of characterization analyses of samples confirmed the proper synthesis of Cu-doped ZnO nanocatalyst. The experimental results indicated the highest degradation efficiency of HS (99.2%) observed using 1.5% Cu-doped ZnO nanoparticles at reaction time of 120 min. Photocatalytic degradation efficiency of HS in a neutral and acidic pH was much higher than that at alkaline pH. Photocatalytic degradation of HS was enhanced with increasing the catalyst dosage and sunlight illuminance, while increasing the initial HS concentration led to decrease in the degradation efficiency of HS. Conclusively, Cu-doped ZnO nanoparticles can be used as a promising and efficient catalyst for degradation of HS under natural sunlight irradiation.

  9. Can simulations quantitatively predict peptide transfer free energies to urea solutions? Thermodynamic concepts and force field limitations.

    PubMed

    Horinek, Dominik; Netz, Roland R

    2011-06-16

    Many proteins denature when they are transferred to concentrated urea solutions. Three mechanisms for urea's denaturing ability have been proposed: (i) direct binding to polar parts of the protein surface, (ii) direct binding to nonpolar parts of the protein surface, and (iii) an indirect effect mediated by modifications of the bulk water properties. The disentanglement of these three processes has been the goal of many experimental and computational studies, yet there is no final agreement on the relative importance of the three contributions. The separation of the two direct mechanisms, albeit conceptually clear, is difficult in experimental studies and in simulations depends subtly on how the discrimination between polar and nonpolar groups is accomplished. Indirect effects, embodied in the change of solution activity as urea is added, are rarely monitored in urea/peptide simulations and thus have remained elusive in numerical studies. In this paper we establish a rigorous separation of all three contributions to the solvation thermodynamics of stretched peptide chains. We contrast this scenario with two commonly used model systems: the air/water interface and the interface between water and a hydrophobic alkane self-assembled monolayer. Together with bulk thermodynamic properties of urea/water mixed solvents, a complete thermodynamic description of the urea/water/peptide system is obtained: urea avoids the air/water interface but readily adsorbs at the oil-water interface and at hydrophobic as well as hydrophilic peptide chains, in accordance with experimental results. Simple thermodynamic arguments show that the indirect contribution to urea's denaturing capability is negligibly small, although urea strongly changes the water bulk properties as judged by the number of hydrogen bonds formed. Urea's tendency to bind to proteins is correctly reproduced with several force field combinations, but the quantitative binding strength as well as the relative importance

  10. Universal reaction mechanism of boronic acids with diols in aqueous solution: kinetics and the basic concept of a conditional formation constant.

    PubMed

    Furikado, Yuki; Nagahata, Tomomi; Okamoto, Takuya; Sugaya, Tomoaki; Iwatsuki, Satoshi; Inamo, Masahiko; Takagi, Hideo D; Odani, Akira; Ishihara, Koji

    2014-10-06

    To establish a detailed reaction mechanism for the condensation between a boronic acid, RB(OH)2, and a diol, H2L, in aqueous solution, the acid dissociation constants (Ka(BL)) of boronic acid diol esters (HBLs) were determined based on the well-established concept of conditional formation constants of metal complexes. The pKa values of HBLs were 2.30, 2.77, and 2.00 for the reaction systems, 2,4-difluorophenylboronic acid and chromotropic acid, 3-nitrophenylboronic acid and alizarin red S, and phenylboronic acid and alizarin red S, respectively. A general and precise reaction mechanism of RB(OH)2 with H2L in aqueous solution, which can serve as a universal reaction mechanism for RB(OH)2 and H2L, was proposed on the basis of (a) the relative kinetic reactivities of the RB(OH)2 and its conjugate base, that is, the boronate ion, toward H2L, and (b) the determined pKa values of HBLs. The use of the conditional formation constant, K', based on the main reaction: RB(OH)2 + H2L (K1)⇌ RB(L)(OH)(-) + H3O(+) instead of the binding constant has been proposed for the general reaction of uncomplexed boronic acid species (B') with uncomplexed diol species (L') to form boronic acid diol complex species (esters, BL') in aqueous solution at pH 5-11: B' + L' (K')⇌ BL'. The proposed reaction mechanism explains perfectly the formation of boronic acid diol ester in aqueous solution.

  11. The Effect of a "Science, Technology and Society" Course on Prospective Teachers' Conceptions of the Nature of Science

    ERIC Educational Resources Information Center

    Celik, Suat; Bayrakceken, Samih

    2006-01-01

    The aim of this study is to assess prospective teachers' views of some aspects of the nature of science (NOS) and the effects of a "Science, Technology and Society" (STS) course embedded with scientific investigation (SI) on these views. A questionnaire consisting of 13 items was given to 212 prospective teachers enrolled in a STS course…

  12. In the Eyes of the Beholder: Beginning Teachers' Conception of the Nature of Science and Science Teaching.

    ERIC Educational Resources Information Center

    Cheung, K. C.; Toh, K. A.

    This paper seeks to explore how beginning elementary school teachers (N=161) in Singapore conceive the scope and nature of science and to understand the relationship between those views and their present approach to, as well as their past experience of, science teaching and learning. Results of an inquiry into the teachers' views indicate that…

  13. Modeling statistics and kinetics of the natural aggregation structures and processes with the solution of generalized logistic equation

    NASA Astrophysics Data System (ADS)

    Maslov, Lev A.; Chebotarev, Vladimir I.

    2017-02-01

    The generalized logistic equation is proposed to model kinetics and statistics of natural processes such as earthquakes, forest fires, floods, landslides, and many others. This equation has the form dN(A)/dA = s dot (1-N(A)) dot N(A)q dot A-α, q>0q>0 and A>0A>0 is the size of an element of a structure, and α≥0. The equation contains two exponents α and q taking into account two important properties of elements of a system: their fractal geometry, and their ability to interact either to enhance or to damp the process of aggregation. The function N(A)N(A) can be understood as an approximation to the number of elements the size of which is less than AA. The function dN(A)/dAdN(A)/dA where N(A)N(A) is the general solution of this equation for q=1 is a product of an increasing bounded function and power-law function with stretched exponential cut-off. The relation with Tsallis non-extensive statistics is demonstrated by solving the generalized logistic equation for q>0q>0. In the case 01q>1 it models sub-additive structures. The Gutenberg-Richter (G-R) formula results from interpretation of empirical data as a straight line in the area of stretched exponent with small α. The solution is applied for modeling distribution of foreshocks and aftershocks in the regions of Napa Valley 2014, and Sumatra 2004 earthquakes fitting the observed data well, both qualitatively and quantitatively.

  14. Nonideal transport of reactive solutes in heterogeneous porous media--4, Analysis of the Cape Cod natural-gradient field experiment

    USGS Publications Warehouse

    Brusseau, Mark L.; Srivastava, Rajesh

    1999-01-01

    One of the largest field studies of reactive-solute transport is the natural-gradient experiment conducted at Cape Cod from 1985 to 1988. Major findings regarding the transport behavior of the reactive solute (lithium) were that the rate of plume displacement decreased with time (temporal increase in effective retardation), the degree of longitudinal spreading was much greater than that observed for bromide for an equivalent travel distance, and the plume was asymmetric, with maximum concentrations located near the leading edges. The objective of our work was to quantitatively analyze the transport of lithium and to attempt to identify the factor or factors that contributed significantly to its observed nonideal transport. We used a mathematical model that accounted for several transport factors, including spatially variable hydraulic conductivity and spatially variable, nonlinear, rate-limited sorption, with all parameter values obtained independently. The transport behavior observed during the first 250 days, corresponding to a transport distance of 60 m, was predicted reasonably well by the simulation that incorporated spatially variable hydraulic conductivity; nonlinear, rate-limited, spatially variable sorption; and uniform water chemistry. However, the larger degree of deceleration observed during the latter stage of the experiment (the filial 20 m) was not. The larger deceleration was successfully simulated by increasing 3-fold the mean sorption capacity of the latter portion of the transport domain. Such a change in sorption capacity is consistent with the potential impact on lithium sorption of measured changes in water chemistry (e.g.,pH increase, reduction in resident Zn)at occur in the zone through which the lithium plume traversed. The results of the analyses suggest that nonlinear sorption and variable water chemistry may have btors responsible for the nonuniform displacement of the lithium plume, with rate-limited sorption/desorption having minimal

  15. Using Multiple Watershed-scale Dye Tracing Tests to Study Water and Solute Transport in Naturally Obstructed Stream Channels

    NASA Astrophysics Data System (ADS)

    Jin, L.; Meeks, J. L.; Hubbard, K. A.; Kurian, L. M.; Siegel, D. I.; Lautz, L. K.; Otz, M. H.

    2007-12-01

    Temporary storage of surface water at channel sides and pools significantly affects water and solute transport downstream in watersheds. Beavers, natural "stream channel engineers", build dams which obstruct stream flow and temporarily store water in small to large ponds within stream channels. These ponds substantially delay water movement and increase the water residence time in the system. To study how water and solutes move through these obstructed stream channels, we did multiple dye tracing tests at Cherry Creek, a main tributary to Red Canyon Creek (Wind River Range, Wyoming). First we surveyed beaver dam distributions in detail within the study reaches. We then introduced dyes four times from July 2nd to 6th, 2007 using a scale-up approach. The observation site was fixed at the mouth of Cherry Creek, and 1.5 grams of Rhodamine WT (RWT) dye was injected sequentially at upstream sites with increasing test reach length. The reach lengths scaled up from 500m to 2.5 km. A field fluorometer recorded RWT concentrations every 15 seconds. The results show non-linear decreases of the peak concentration of the dye tracing cloud as the reach scaled up. Also, the times to 1.) the arrivals of the leading edges (Tl), 2.) the peak concentrations (Tp) and 3.) the tailing edges (Tt) and 4) the durations of the tracer cloud (Td) behaved non-linearly as function of length scale. For example, plots of arrivals of leading edges and tailing edges with scale distance appear to define curves of the form; Tl=27.665e1.07× Distance (r2=0.99) and Tt=162.62e0.8551× Distance (r2=0.99), respectively. The greatest non-linearity occurred for the time of tailing and the least for the time of leading edge. These observations are consistent with what would be expected with greater density of dams and/or storage volumes as the reach length increased upgradient. To come to a first approximation, we are currently modeling the breakthrough curves with the solute transport code OTIS to address

  16. Mechanisms of degradation of the natural high-potency sweetener (2R,4R)-monatin in mock beverage solutions.

    PubMed

    Storkey, Corin; Pattison, David I; Gaspard, Dan S; Hagestuen, Erik D; Davies, Michael J

    2014-04-16

    The sodium, potassium, or mixed sodium/potassium salt of the naturally occurring high-potency sweetener (2R,4R)-monatin, also known by the common name arruva, degrades over time in model beverage solutions in the presence of light. By use of UHPLC, LC-MS/MS, and peroxide assays, it has been demonstrated that degradation is accelerated by UV/visible light and the presence of trace metal ions. Data are presented that are consistent with a role for singlet oxygen (¹O₂), free radicals, and peroxides (both H₂O₂ and organic peroxides) in monatin oxidation. Separation of degradation products by UHPLC/HPLC or LC-MS/MS provided evidence for the formation of hydroxylated and peroxide species formed on the indole ring (mass increases 16 and 32, respectively) as well as multiple ring and side-chain oxidation and scission products. Model oxidation systems using the photosensitizer Rose Bengal as a source of ¹O₂ support the proposed photodegradation pathways.

  17. Direct chemiluminescence detection of nitric oxide in aqueous solutions using the natural nitric oxide target soluble guanylyl cyclase.

    PubMed

    Woldman, Yakov Y; Sun, Jian; Zweier, Jay L; Khramtsov, Valery V

    2009-11-15

    Nitric oxide (NO) is a free radical involved in many physiological processes including regulation of blood pressure, immune response, and neurotransmission. However, the measurement of extremely low, in some cases subnanomolar, physiological concentrations of nitric oxide presents an analytical challenge. The purpose of this methods article is to introduce a new highly sensitive chemiluminescence approach to direct NO detection in aqueous solutions using a natural nitric oxide target, soluble guanylyl cyclase (sGC), which catalyzes the conversion of guanosine triphosphate to guanosine 3',5'-cyclic monophosphate and inorganic pyrophosphate. The suggested enzymatic assay uses the fact that the rate of the reaction increases by about 200 times when NO binds with sGC and, in so doing, provides a sensor for nitric oxide. Luminescence detection of the above reaction is accomplished by converting inorganic pyrophosphate into ATP with the help of ATP sulfurylase followed by light emission from the ATP-dependent luciferin-luciferase reaction. Detailed protocols for NO quantification in aqueous samples are provided. The examples of applications include measurement of NO generated by a nitric oxide donor (PAPA-NONOate), nitric oxide synthase, and NO gas dissolved in buffer. The method allows for the measurement of NO concentrations in the nanomolar range and NO generation rates as low as 100 pM/min.

  18. Seven out of 10 couples treated by IVF achieve parenthood following either treatment, natural conception or adoption.

    PubMed

    Troude, Pénélope; Santin, Gaëlle; Guibert, Juliette; Bouyer, Jean; de La Rochebrochard, Elise

    2016-11-01

    The aim of this study was to explore the achievement of parenthood 8 years after starting IVF, considering multiple pathways to parenthood during and after IVF treatment. Medical data on 6507 couples who began IVF between 2000 and 2002 were obtained from the databases of eight French IVF centres. Information on long-term outcome was available for participants in the 2008-2010 postal survey. Multiple imputation methods were used to account for missing data. Eight years after starting IVF, 71% (95% CI 69 to 74) of treated couples had a child. This included 41% live births after IVF in the IVF centre, 7% live births after another treatment or after IVF in another centre, 12% live births after spontaneous conception and 11% adoptions. This study provides a longitudinal overview of paths to parenthood among couples successfully and unsuccessfully treated by IVF. These results should give hope to infertile couples as seven out of 10 couples finally became parents. However, IVF is not the only path to parenthood, and couples should be informed of the other possible avenues.

  19. Edaq530: A Transparent, Open-End and Open-Source Measurement Solution in Natural Science Education

    ERIC Educational Resources Information Center

    Kopasz, Katalin; Makra, Peter; Gingl, Zoltan

    2011-01-01

    We present Edaq530, a low-cost, compact and easy-to-use digital measurement solution consisting of a thumb-sized USB-to-sensor interface and measurement software. The solution is fully open-source, our aim being to provide a viable alternative to professional solutions. Our main focus in designing Edaq530 has been versatility and transparency. In…

  20. Assessing allergenicity in urban parks: A nature-based solution to reduce the impact on public health.

    PubMed

    Cariñanos, Paloma; Casares-Porcel, Manuel; Díaz de la Guardia, Consuelo; Aira, María Jesús; Belmonte, Jordina; Boi, Marzia; Elvira-Rendueles, Belén; De Linares, Concepción; Fernández-Rodriguez, Santiago; Maya-Manzano, José María; Pérez-Badía, Rosa; Rodriguez-de la Cruz, David; Rodríguez-Rajo, Francisco Javier; Rojo-Úbeda, Jesús; Romero-Zarco, Carlos; Sánchez-Reyes, Estefanía; Sánchez-Sánchez, José; Tormo-Molina, Rafael; Vega Maray, Ana Mª

    2017-02-20

    Urban parks play a key role in the provision of ecosystem services, actively participating in improving the quality of life and welfare of local residents. This paper reports on the application of an index designed to quantify the allergenicity of urban parks in a number of Spanish cities. The index, which records biological and biometric parameters for the tree species growing there, classifies parks in terms of the risk they pose for allergy sufferers, graded as null, low, moderate or high. In this initial phase, the index was applied to 26 green areas in 24 Spanish cities; green areas varied in type (urban park, historical or modern garden, boulevard, square or urban forest), size 1-100 ha), geographical location, species richness, number of trees and tree density (number of trees / ha.). The data obtained were used to calculate the percentage of allergenic species in each park, which varied between 17-67%; density ranged from 100 to 300 trees/ha. The index values recorded ranged from a minimum of .07 to a maximum of .87; a significant correlation was found between index value and both number of trees and tree density. Taking an index value of .30 as the threshold considered sufficient to trigger allergy symptoms in the sensitive population, 12 of the parks studied may be regarded as unhealthy at any time of the year. Corrective measures to mitigate the impact of pollen emissions include the implementation of nature-based solutions at various levels: planning and design, handling and management, and strengthening of urban green-infrastructure elements. The index proved to be a useful tool for environmental analysis, and complies with the principles of portability and scalability central to current and horizon scientific research.

  1. Solution-Focused Approaches in the Practice of UK Educational Psychologists: A Study of the Nature of Their Application and Evidence of Their Effectiveness

    ERIC Educational Resources Information Center

    Stobie, Ingeborg; Boyle, James; Woolfson, Lisa

    2005-01-01

    Solution-focused approaches are increasingly widely used in the practice of the applied educational psychologist (EP) (Ajmal and Rees, 2001; Durrant, 1993; Redpath and Harper, 1999; Rhodes and Ajmal, 1995). Based on a small-scale computer-mediated exploratory survey, this article examines the nature of such practice and investigates whether and…

  2. Ruptured heterotopic pregnancy in a natural conception cycle: a case report at the Yaounde central Hospital (Cameroon)

    PubMed Central

    Fouedjio, Jeanne Hortence; Fouelifack, Florent Ymele; Fouogue, Jovanny Tsuala; Sando, Zacharie

    2013-01-01

    Heterotopic pregnancy is very rare under natural circumstances. We report the case of a 28 year old Gravida2 Para1001 woman at 9 weeks of pregnancy who consulted in emergency for acute pelvic pain following metrorrhagia. Physical exam revealed hemoperitoneum without shock. An emergency ultrasonography revealed two gestational sacs, one intra-uterine and the other extra-uterine. Laparotomy was done and the findings were: a ruptured right tubal pregnancy with 1,300 milliliters of hemoperitoneum, type B left utero-adnexal adhesions and an increased uterus consistent with a 9 weeks pregnancy. Right total salpingectomy was done and the patient did well postoperatively. That intrauterine pregnancy evolved normally under progesterone supply and the woman delivered a termed live female baby weighing 3.1 kilogrammes. In our context where ultrasound is not always available, practitioners carrying out salpingectomy for ruptured ectopic pregnancies should bear in mind the plausibleness of heterotopic pregnancy in order to properly handle the uterus. PMID:24876895

  3. An examination of an aspect of the worldview of female college science teachers as revealed by their concepts of nature

    NASA Astrophysics Data System (ADS)

    Tryon, Lisa A.

    American citizens are confronted every day with scientific issues such as global warming, alternative energy technologies, stem cell research, and the use of genetically modified foods. A scientifically literate adult should be able to understand these issues, see how they relate to their own lives, and make choices that reflect their knowledge of the problems at hand. Research has indicated that the majority of U.S. students are not prepared to take a proactive role in current scientific issues and so undergraduate educators are being charged with the task of improving the relevancy of science to the nonscience student. One method for exploring this problem has been the application of worldview theory, which seeks to analyze the thoughts and attitudes of teachers and students with regard to science in their lives. This qualitative case study sought to uncover the worldviews of female science college professors particularly as they related to nature and to examine how these educators felt their worldviews might influence their students. A series of established card sort activities used in previous worldview studies, in combination with an in-depth interview facilitated the data collection from female science professors teaching at universities in New England.

  4. Hybridization of natural systems with advanced treatment processes for organic micropollutant removals: new concepts in multi-barrier treatment.

    PubMed

    Sudhakaran, Sairam; Maeng, Sung Kyu; Amy, Gary

    2013-07-01

    Organic micropollutants (OMPs) represent a major constraint in drinking water supply. In the past, emphasis has been on individual treatment processes comprising conventional treatment (coagulation, sedimentation, and filtration) followed by advanced treatment processes (adsorption, ion-exchange, oxidation, and membrane separation). With the depletion of water resources and high demand for power and chemical usage, efforts need to be made to judiciously use advanced treatment processes. There is a new interest in multiple barriers with synergies in which two coupled processes can function as a hybrid process. Within the context of this paper, the hybrid processes include a natural treatment process coupled with an advanced process. Pilot/full-scale studies have shown efficient removal of OMPs by these hybrid processes. With this hybridization, the usage of resources such as power and chemicals can be reduced. In this study, coupling/hybridization of aquifer recharge and recovery (ARR) with oxidation (O3), advanced oxidation process which involves OH radicals (AOP), nanofiltration (NF), reverse osmosis (RO) and granular activated carbon (GAC) adsorption for OMP removal was studied. O3 or AOP as a pre-treatment and GAC, NF, RO, or UV/chlorination as a post-treatment to ARR was studied. NF can be replaced by RO for removal of OMPs since studies have shown similar performance of NF to RO for removal of many OMPs, thereby reducing costs and providing a more sustainable approach.

  5. Inferences of body energy reserves on conception rate of suckled Zebu beef cows subjected to timed artificial insemination followed by natural mating.

    PubMed

    Ayres, H; Ferreira, R M; Torres-Júnior, J R S; Demétrio, C G B; Sá Filho, M F; Gimenes, L U; Penteado, L; D'Occhio, M J; Baruselli, P S

    2014-09-01

    The influence of body condition score (BCS), rump fat thickness (RFAT), and live weight (LW), and the changes in these parameters during the interval from 165 of prepartum (i.e., 125 days of prior gestation) to 112 postpartum on first service conception and pregnancy rates were investigated in suckled Zebu (Bos indicus) beef cows (n = 266) subjected to timed artificial insemination (TAI) followed by natural mating. The aforementioned parameters were recorded at 165 ± 14 days (mean ± standard error) prepartum (concurrent with the weaning of previous calf), at parturition, and at 42 ± 7 days (at the onset of the synchronization of ovulation protocol), 82 ± 7 days (30 days after TAI), and 112 ± 7 days (60 days after TAI) postpartum. At the start of the breeding season (BS), cows were subjected to a synchronization of ovulation program for TAI. Bulls were placed with cows 10 days after TAI and remained until the end of the study (112 days postpartum). Cows with the highest BCS at parturition had an increased probability of first service conception rate at 60 days after TAI (P = 0.02) and a reduced probability of occurrence of pregnancy loss (P = 0.05). Also, cows had a greater likelihood of conceiving postpartum if they had greater RFAT and BCS at 165 ± 14 days prepartum (P = 0.01 and P = 0.03, respectively) and at parturition (P = 0.0007 and P = 0.003, respectively). Cows that had an increase in RFAT and BCS during the dry period (i.e., interval from weaning of the previous calf to parturition) also had a greater likelihood of conceiving (P = 0.03 and P = 0.06, respectively) during the BS. Among the different time points, RFAT and BCS at parturition had the largest impact on risk of conception during the BS. The LW was a poor predictor of conception during the BS (P = 0.11-0.68) except for LW at 165 ± 14 days prepartum (P = 0.01). Collectively, the findings indicated that the likelihood of conception during the BS

  6. The influence of the history of science course on pre-service science teachers' understanding of the nature of science concepts

    NASA Astrophysics Data System (ADS)

    Akcay, Behiye

    The purpose of this study was to investigate the influence of a history of science course on pre-service science teachers' understanding of the nature of science concepts. Subjects in the study were divided in two groups: (1) students who enrolled in only in the history of science course, (2) students who enrolled both the meaning of science and the history of science courses. An interpretative-descriptive approach and constant comparative analysis were used to identify similarities and differences among pre-service teachers' views about nature of scientific knowledge prior to and after the history of science course. The results of this study indicate that explicitly addressing certain aspects of the nature of science is effective in promoting adequate understanding of the nature of science for pre-service science teachers. Moreover, the results indicate that a student's prior experience with the history of science helps to improve their understanding of the history and nature of science. The history of science course helped pre-service teachers to develop the following views which are parallel with these advocated in both the Benchmarks (AAAS, 1993) and the National Science Education Standards (NRC, 1996) concerning the nature of scientific knowledge: (1) Scientific knowledge is empirically based and an ongoing process of experimentation, investigation, and observation. (2) Science is a human endeavor. (3) People from different cultures, races, genders, and nationality contribute to science. (4) Scientific knowledge is not based on myths, personal beliefs, and religious values. (5) Science background and prior knowledge have important roles for scientific investigations. (6) Scientific theories and laws represent different kinds of knowledge. (7) Science is affected by political, social, and cultural values. (8) Creativity and imagination are used during all stages of scientific investigations. (9) Theories change because of new evidence and new views of existing

  7. Context, accuracy, and level of inclusion of nature of science concepts in current high school physics textbooks

    NASA Astrophysics Data System (ADS)

    Alshamrani, Saeed Mohammed

    To improve K-12 students' images of the nature of science (NOS) through science textbooks, two issues must be addressed: (a) the level of NOS that ought to be included in science textbooks and (b) the treatment of this level in those textbooks. Science educators achieved a consensus level of agreement regarding what NOS aspects should be taught for K-12 science learners; however, there is a need for more clarification regarding the actual treatment of NOS in science textbooks. The purpose of this study is to investigate the NOS inclusion in high school physics textbooks. To be specific, this study examines the included NOS aspects, the frequency of NOS inclusion, the contexts exist for NOS inclusion, and the accuracy of NOS inclusion. This study utilized 12 science education studies to develop the Master Aspects of Nature of Science [MA-NOS] which includes 12 NOS aspects that ought to be included in K-12 science curriculum. The analyzed textbooks in this study are seven textbooks identified by The American Institute of Physics as the most widely used high school physics textbooks in the United States in 2005. These textbooks were used in teaching five academic levels: (a) Regular First-Year Physics, (b) Physics for Non-Science Students, (c) Honors Physics, (d) AP-B Physics, and (e) AP-C Physics. The researcher selected exclusively physics textbooks because physics is his main interest. To facilitate the content analysis of the selected textbooks, the study developed The Collection Data Coding Guide which includes six parts describing the MA-NOS aspects and the process of identifying and collecting data. For each NOS aspect, a description and one or more selected ideal indicators were provided to facilitate data collecting and judging the accuracy of NOS inclusion. This coding guide was reviewed for its content validity by two science educators who specialize in NOS. However, two types of reliability were conducted to identify the consistency of selecting NOS units

  8. Focusing on the Classical or Contemporary? Chinese Science Teacher Educators' Conceptions of Nature of Science Content to Be Taught to Pre-service Science Teachers

    NASA Astrophysics Data System (ADS)

    Wan, Zhi Hong; Wong, Siu Ling; Wei, Bing; Zhan, Ying

    2013-12-01

    Drawing from the phenomenographic perspective, an exploratory study investigated Chinese teacher educators' conceptions of teaching Nature of Science (NOS) to pre-service science teachers through semi-structured interviews. Five key dimensions emerged from the data. This paper focuses on the dimension, NOS content to be taught to pre-service science teachers. A total of 20 NOS elements were considered by the Chinese science teacher educators to be important ideas to be taught. It was also found that among these educators, whether focusing on the classical or contemporary NOS elements in NOS instruction was a prominent controversy. After explaining the criteria for differentiating between classical and contemporary NOS elements, this paper reports the specific NOS elements suggested by Chinese science teacher educators in this study. Afterward, it describes how all educators in this study were categorized in term of NOS content taught by them to pre-service science teachers. In the end, it discusses three factors influencing the decision on NOS content to be taught, i.e., view of the concept of NOS itself, vision of teaching NOS, and belief in general philosophy.

  9. Nature inspired computational technique for the numerical solution of nonlinear singular boundary value problems arising in physiology.

    PubMed

    Malik, Suheel Abdullah; Qureshi, Ijaz Mansoor; Amir, Muhammad; Haq, Ihsanul

    2014-01-01

    We present a hybrid heuristic computing method for the numerical solution of nonlinear singular boundary value problems arising in physiology. The approximate solution is deduced as a linear combination of some log sigmoid basis functions. A fitness function representing the sum of the mean square error of the given nonlinear ordinary differential equation (ODE) and its boundary conditions is formulated. The optimization of the unknown adjustable parameters contained in the fitness function is performed by the hybrid heuristic computation algorithm based on genetic algorithm (GA), interior point algorithm (IPA), and active set algorithm (ASA). The efficiency and the viability of the proposed method are confirmed by solving three examples from physiology. The obtained approximate solutions are found in excellent agreement with the exact solutions as well as some conventional numerical solutions.

  10. Nature Inspired Computational Technique for the Numerical Solution of Nonlinear Singular Boundary Value Problems Arising in Physiology

    PubMed Central

    Malik, Suheel Abdullah; Qureshi, Ijaz Mansoor; Haq, Ihsanul

    2014-01-01

    We present a hybrid heuristic computing method for the numerical solution of nonlinear singular boundary value problems arising in physiology. The approximate solution is deduced as a linear combination of some log sigmoid basis functions. A fitness function representing the sum of the mean square error of the given nonlinear ordinary differential equation (ODE) and its boundary conditions is formulated. The optimization of the unknown adjustable parameters contained in the fitness function is performed by the hybrid heuristic computation algorithm based on genetic algorithm (GA), interior point algorithm (IPA), and active set algorithm (ASA). The efficiency and the viability of the proposed method are confirmed by solving three examples from physiology. The obtained approximate solutions are found in excellent agreement with the exact solutions as well as some conventional numerical solutions. PMID:24672381

  11. Re-implantation of cryopreserved ovarian cortex resulting in restoration of ovarian function, natural conception and successful pregnancy after haematopoietic stem cell transplantation for Wilms tumour.

    PubMed

    Dunlop, C E; Brady, B M; McLaughlin, M; Telfer, E E; White, J; Cowie, F; Zahra, S; Wallace, W H B; Anderson, R A

    2016-12-01

    With the improvement of long-term cancer survival rates, growing numbers of female survivors are suffering from treatment-related premature ovarian insufficiency (POI). Although pre-treatment embryo and oocyte storage are effective fertility preservation strategies, they are not possible for pre-pubertal girls or women who cannot delay treatment. In these cases, the only available treatment option is ovarian cortex cryopreservation and subsequent re-implantation. A 32-year-old woman had ovarian cortex cryopreserved 10 years previously before commencing high-dose chemotherapy and undergoing a haematopoietic stem cell transplant for recurrent adult Wilms tumour, which resulted in POI. She underwent laparoscopic orthotopic transplantation of cryopreserved ovarian cortex to the original site of biopsy on the left ovary. She ovulated at 15 and 29 weeks post-re-implantation with AMH detectable, then rising, from 21 weeks, and conceived naturally following the second ovulation. The pregnancy was uncomplicated and a healthy male infant was born by elective Caesarean section at 36(+4) weeks gestation. This is the first report of ovarian cortex re-implantation in the UK. Despite the patient receiving low-risk chemotherapy prior to cryopreservation and the prolonged tissue storage duration, the re-implantation resulted in rapid restoration of ovarian function and natural conception with successful pregnancy.

  12. An Application of Ausubel's Learning Theory to Environmental Education: A Study of Concept Mapping in a College Natural Resources Management Course.

    ERIC Educational Resources Information Center

    Bousquet, Woodward Scott

    Based upon Ausubel's theory of meaningful learning, this study focused on the use of concept maps (diagrams that portray relationships among concepts in a given area of study) to help students identify logical relationships between a new concept and concepts already known. Relationships of a learner's prior knowledge and cognitive development to…

  13. When Do Short-Wave Cones Signal Blue or Red? A Solution Introducing the Concept of Primary and Secondary Cone Outputs

    PubMed Central

    2016-01-01

    A recent paper by Oh and Sakata investigates the “incompletely solved mystery” of how the three cone responses map onto perceived hue, and particularly the S cone’s well-known problematic contribution to blueness and redness. Citing previous workers, they argue the twentieth century traditional multistage model does not satisfactorily account for color appearance. In their experiment, increasing S cone excitation with shortening wavelength from about 480–460 nm increased perceived blueness up to the unique Blue point at 470 nm, when (a) it began decreasing and (b) redness perception began increasing. The authors asked, What mechanism can be responsible for such functions? I demonstrate a solution. First, it is shown the problem does not lie in the traditional opponent color chromatic responses yellow-blue, red-green (y-b, r-g, which accurately predict the above functions), but in the traditional multistage model of mapping cone responses to chromatic response functions. Arguably, this is due to the S cone’s hypothetically signaling both blueness and redness by the same mechanism rather than by different, independent, mechanisms. Hence a new distinction or mechanism is proposed for a more accurate model, that introduces the new terms primary and secondary cone outputs. However, this distinction requires that the cones S, M, L each directly produce one of the three spectral chromatic responses b, g, y. Such a model was recently published, based on extremely high correlation of SML cone responsivities with the three spectral (bgy) chromatic responses. This model encodes the former directly onto the latter one-to-one as cone primary outputs, whilst S and L cones have a further or secondary function where each produces one of the two spectral lobes of r chromatic response. The proposed distinction between primary and secondary cone outputs is a new concept and useful tool in detailing cone outputs to chromatic channels, and provides a solution to the above

  14. When Do Short-Wave Cones Signal Blue or Red? A Solution Introducing the Concept of Primary and Secondary Cone Outputs.

    PubMed

    Pridmore, Ralph W

    2016-01-01

    A recent paper by Oh and Sakata investigates the "incompletely solved mystery" of how the three cone responses map onto perceived hue, and particularly the S cone's well-known problematic contribution to blueness and redness. Citing previous workers, they argue the twentieth century traditional multistage model does not satisfactorily account for color appearance. In their experiment, increasing S cone excitation with shortening wavelength from about 480-460 nm increased perceived blueness up to the unique Blue point at 470 nm, when (a) it began decreasing and (b) redness perception began increasing. The authors asked, What mechanism can be responsible for such functions? I demonstrate a solution. First, it is shown the problem does not lie in the traditional opponent color chromatic responses yellow-blue, red-green (y-b, r-g, which accurately predict the above functions), but in the traditional multistage model of mapping cone responses to chromatic response functions. Arguably, this is due to the S cone's hypothetically signaling both blueness and redness by the same mechanism rather than by different, independent, mechanisms. Hence a new distinction or mechanism is proposed for a more accurate model, that introduces the new terms primary and secondary cone outputs. However, this distinction requires that the cones S, M, L each directly produce one of the three spectral chromatic responses b, g, y. Such a model was recently published, based on extremely high correlation of SML cone responsivities with the three spectral (bgy) chromatic responses. This model encodes the former directly onto the latter one-to-one as cone primary outputs, whilst S and L cones have a further or secondary function where each produces one of the two spectral lobes of r chromatic response. The proposed distinction between primary and secondary cone outputs is a new concept and useful tool in detailing cone outputs to chromatic channels, and provides a solution to the above "incompletely

  15. The science knowledge, conceptions of the nature of science, attitudes about teaching science, and science instructional strategies of bilingual and English-only elementary teachers

    NASA Astrophysics Data System (ADS)

    Alegria, Adelina Victoria

    The goal of this study was to explore bilingual and English-only elementary teachers' science knowledge, their conceptions of the nature of science, their attitudes about teaching science, and their self-reported science instructional skills. In this study, a bilingual teacher was defined as a teacher who provides instruction in Spanish and English in core academic subjects and has completed and/or is completing a bilingual certification program. An English-only teacher was defined as a monolingual teacher that only speaks and instructs in English. The principal questions guiding this dissertation investigation were the following: How do bilingual elementary teachers differ from English-only elementary teachers in (a) their science knowledge, (b) their conceptions of the nature of science, (c) their attitude about teaching science, and (d) their self-reported science instructional skills? This dissertation study is a component of a three-year long Eisenhower Project granted to Hueneme School District and the University of California, Santa Barbara Southcoast Science Project. While the Project will last three years (1997--2000), this dissertation study was developed to answer only a subset of questions of the entire project and data was collected in 1998. The research design for this study consisted of a self-administered questionnaire that was given to Hueneme School District elementary teachers that teach science and was developed by reviewing the relevant literature about teachers' science knowledge, their conceptions of the nature of science, their attitudes about teaching science, and the instructional strategies that support science learning. The findings showed that both the bilingual and the English-only respondents demonstrated a similar science knowledge base, which is suggested, by this researcher, to be limited. That both bilingual and English-only teacher respondents demonstrated similar positive attitudes about teaching science and both reported making

  16. Solubilities of methane, nitrogen, carbon dioxide, and a natural gas mixture in aqueous sodium bicarbonate solutions under high pressure and elevated temperature

    SciTech Connect

    Gao, J.; Zheng, D.Q.; Guo, T.M.

    1997-01-01

    The solubility of natural gas mixtures in formation water (brine) plays an important role in estimating the natural gas reserve, the formation/dissociation conditions of methane hydrates in situ, and the interfacial tension of the hydrocarbon-formation water system. However, solubility data at high pressure and elevated temperature conditions for aqueous electrolyte systems are rare. Recently, in the reservoirs found at the South China Sea areas, the main salt species in the formation water is sodium bicarbonate, and the solubility data of gases in aqueous sodium bicarbonate solutions under reservoir conditions have not previously been reported. An apparatus for measuring the solubility of gases in aqueous electrolyte solutions under high pressure and elevated temperature conditions is described. The solubility of methane, carbon dioxide, nitrogen, and a natural gas mixture in aqueous sodium bicarbonate solutions were measured up to 58 MPa and 403 K. The modified Patel-Teja equation of state proposed by Zuo and Guo (1991) for aqueous electrolyte systems was applied to correlate the measured solubility data, and satisfactory results were obtained.

  17. Computing Liquid-Liquid Phase Equilibria: An Exercise for Understanding the Nature of False Solutions and How to Avoid Them

    ERIC Educational Resources Information Center

    Olaya, Maria del Mar; Ibarra, Isabel; Reyes-Labarta, Juan A.; Serrano, Maria Dolores; Marcilla, Antonio

    2007-01-01

    An exercise to compute LLE data is presented to illustrate the problems that can arise when the isoactivity equilibrium condition is used in the LLE calculations. A much more efficient condition is obtained when isoactivity is combined with the common tangent line criterion, avoiding false solutions that correspond with very low values of the…

  18. Plants increase arsenic in solution but decrease the non-specifically bound fraction in the rhizosphere of an alkaline, naturally rich soil.

    PubMed

    Obeidy, Carole; Bravin, Matthieu N; Bouchardon, Jean-Luc; Conord, Cyrille; Moutte, Jacques; Guy, Bernard; Faure, Olivier

    2016-04-01

    We aimed at determining the major physical-chemical processes that drive arsenic (As) dynamic in the rhizosphere of four species (Holcus lanatus, Dittrichia viscosa, Lotus corniculatus, Plantago lanceolata) tested for phytostabilization. Experiments were performed with an alkaline soil naturally rich in As. Composition of the soil solution of planted and unplanted pots was monitored every 15 days for 90 days, with a focus on the evolution of As concentrations in solution and in the non-specifically bound (i.e. easily exchangeable) fraction. The four species similarly increased As concentration in solution, but decreased As concentration in the non-specifically bound fraction. The major part (60%) of As desorbed from the non-specifically bound fraction in planted pots was likely redistributed on the less available fractions of As on the solid phase. A second part (35%) of desorbed As was taken up by plants. The minor part (5%) of desorbed As supplied As increase in solution. To conclude, plants induced a substantial redistribution of As on the less available fractions in the rhizosphere, as expected in phytostabilization strategies. Plants however concomitantly increased As concentration in the rhizosphere solution which may contribute to As transfer through plant uptake and leaching.

  19. Uncertainty of streamwater solute fluxes in five contrasting headwater catchments including model uncertainty and natural variability (Invited)

    NASA Astrophysics Data System (ADS)

    Aulenbach, B. T.; Burns, D. A.; Shanley, J. B.; Yanai, R. D.; Bae, K.; Wild, A.; Yang, Y.; Dong, Y.

    2013-12-01

    There are many sources of uncertainty in estimates of streamwater solute flux. Flux is the product of discharge and concentration (summed over time), each of which has measurement uncertainty of its own. Discharge can be measured almost continuously, but concentrations are usually determined from discrete samples, which increases uncertainty dependent on sampling frequency and how concentrations are assigned for the periods between samples. Gaps between samples can be estimated by linear interpolation or by models that that use the relations between concentration and continuously measured or known variables such as discharge, season, temperature, and time. For this project, developed in cooperation with QUEST (Quantifying Uncertainty in Ecosystem Studies), we evaluated uncertainty for three flux estimation methods and three different sampling frequencies (monthly, weekly, and weekly plus event). The constituents investigated were dissolved NO3, Si, SO4, and dissolved organic carbon (DOC), solutes whose concentration dynamics exhibit strongly contrasting behavior. The evaluation was completed for a 10-year period at five small, forested watersheds in Georgia, New Hampshire, New York, Puerto Rico, and Vermont. Concentration regression models were developed for each solute at each of the three sampling frequencies for all five watersheds. Fluxes were then calculated using (1) a linear interpolation approach, (2) a regression-model method, and (3) the composite method - which combines the regression-model method for estimating concentrations and the linear interpolation method for correcting model residuals to the observed sample concentrations. We considered the best estimates of flux to be derived using the composite method at the highest sampling frequencies. We also evaluated the importance of sampling frequency and estimation method on flux estimate uncertainty; flux uncertainty was dependent on the variability characteristics of each solute and varied for

  20. A review of selected pumping systems in nature and engineering--potential biomimetic concepts for improving displacement pumps and pulsation damping.

    PubMed

    Bach, D; Schmich, F; Masselter, T; Speck, T

    2015-09-03

    The active transport of fluids by pumps plays an essential role in engineering and biology. Due to increasing energy costs and environmental issues, topics like noise reduction, increase of efficiency and enhanced robustness are of high importance in the development of pumps in engineering. The study compares pumps in biology and engineering and assesses biomimetic potentials for improving man-made pumping systems. To this aim, examples of common challenges, applications and current biomimetic research for state-of-the art pumps are presented. The biomimetic research is helped by the similar configuration of many positive displacement pumping systems in biology and engineering. In contrast, the configuration and underlying pumping principles for fluid dynamic pumps (FDPs) differ to a greater extent in biology and engineering. However, progress has been made for positive displacement as well as for FDPs by developing biomimetic devices with artificial muscles and cilia that improve energetic efficiency and fail-safe operation or reduce noise. The circulatory system of vertebrates holds a high biomimetic potential for the damping of pressure pulsations, a common challenge in engineering. Damping of blood pressure pulsation results from a nonlinear viscoelastic behavior of the artery walls which represent a complex composite material. The transfer of the underlying functional principle could lead to an improvement of existing technical solutions and be used to develop novel biomimetic damping solutions. To enhance efficiency or thrust of man-made fluid transportation systems, research on jet propulsion in biology has shown that a pulsed jet can be tuned to either maximize thrust or efficiency. The underlying principle has already been transferred into biomimetic applications in open channel water systems. Overall there is a high potential to learn from nature in order to improve pumping systems for challenges like the reduction of pressure pulsations, increase of jet

  1. Pareto-optimal solutions for environmental flow schemes incorporating the intra-annual and interannual variability of the natural flow regime

    NASA Astrophysics Data System (ADS)

    Shiau, Jenq-Tzong; Wu, Fu-Chun

    2007-06-01

    The temporal variations of natural flows are essential elements for preserving the ecological health of a river which are addressed in this paper by the environmental flow schemes that incorporate the intra-annual and interannual variability of the natural flow regime. We present an optimization framework to find the Pareto-optimal solutions for various flow schemes. The proposed framework integrates (1) the range of variability approach for evaluating the hydrologic alterations; (2) the standardized precipitation index approach for establishing the variation criteria for the wet, normal, and dry years; (3) a weir operation model for simulating the system of flows; and (4) a multiobjective optimization genetic algorithm for search of the Pareto-optimal solutions. The proposed framework is applied to the Kaoping diversion weir in Taiwan. The results reveal that the time-varying schemes incorporating the intra-annual variability in the environmental flow prescriptions promote the ecosystem and human needs fitness. Incorporation of the interannual flow variability using different criteria established for three types of water year further promotes both fitnesses. The merit of incorporating the interannual variability may be superimposed on that of incorporating only the intra-annual flow variability. The Pareto-optimal solutions searched with a limited range of flows replicate satisfactorily those obtained with a full search range. The limited-range Pareto front may be used as a surrogate of the full-range one if feasible prescriptions are to be found among the regular flows.

  2. Clastic dikes of the Hatrurim basin (western flank of the Dead Sea) as natural analogues of alkaline concretes: Mineralogy, solution chemistry, and durability

    NASA Astrophysics Data System (ADS)

    Sokol, E. V.; Gaskova, O. L.; Kozmenko, O. A.; Kokh, S. N.; Vapnik, E. A.; Novikova, S. A.; Nigmatulina, E. N.

    2014-11-01

    This study shows that the mineral assemblages from clastic dikes in areas adjacent to the Dead Sea graben may be considered as natural analogues of alkaline concretes. The main infilling material of the clastic dikes is composed of well-sorted and well-rounded quartz sand. The cement of these hard rocks contains hydroxylapophyllite, tacharanite, calcium silicate hydrates, opal, calcite, and zeolite-like phases, which is indicative of a similarity of the natural cementation processes and industrial alkaline concrete production from quartz sands and industrial alkaline cements. The quartz grains exhibit a variety of reaction textures reflecting the interaction with alkaline solutions (opal and calcium hydrosilicate overgrowths; full replacement with apophyllite or thomsonite + apophyllite). The physicochemical analysis and reconstruction of the chemical composition of peralkaline Ca, Na, and K solutions that formed these assemblages reveal that the solutions evolved toward a more stable composition of zeolite-like phases, which are more resistant to long-term chemical weathering and atmospheric corrosion. The 40Ar/39Ar age of 6.2 ± 0.7 Ma obtained for apophyllite provides conclusive evidence for the high corrosion resistance of the assemblages consisting of apophyllite and zeolite-like phases.

  3. Natural dissolved organic matter mobilizes Cd but does not affect the Cd uptake by the green algae Pseudokirchneriella subcapitata (Korschikov) in resin buffered solutions.

    PubMed

    Verheyen, Liesbeth; Versieren, Liske; Smolders, Erik

    2014-09-01

    Natural dissolved organic matter (DOM) can have contrasting effects on metal bioaccumulation in algae because of complexation reactions that reduce free metal ion concentrations and because of DOM adsorption to algal surfaces which promote metal adsorption. This study was set up to reveal the role of different natural DOM samples on cadmium (Cd) uptake by the green algae Pseudokirchneriella subcapitata (Korschikov). Six different DOM samples were collected from natural freshwater systems and isolated by reverse osmosis. In addition, one (13)C enriched DOM sample was isolated from soil to trace DOM adsorption to algae. Algae were exposed to standardized solutions with or without these DOM samples, each exposed at equal DOM concentrations and at equal non-toxic Cd(2+) activity (∼4 nM) that was buffered with a resin. The DOM increased total dissolved Cd by factors 3-16 due to complexation reactions at equal Cd(2+) activity. In contrast, the Cd uptake was unaffected by DOM or increased maximally 1.6 fold ((13)C enriched DOM). The (13)C analysis revealed that maximally 6% of algal C was derived from DOM and that this can explain the small increase in biomass Cd. It is concluded that free Cd(2+) and not DOM-complexed Cd is the main bioavailable form of Cd when solution Cd(2+) is well buffered.

  4. Solving for Efficiency or Decision Criteria: When the Non-unique Nature of Solutions Becomes a Benefit

    NASA Astrophysics Data System (ADS)

    Pierce, S. A.; Ciarleglio, M.; Dulay, M.; Lowry, T. S.; Sharp, J. M.; Barnes, J. W.; Eaton, D. J.; Tidwell, V. C.

    2006-12-01

    Work in the literature for groundwater allocation emphasizes finding a truly optimal solution, often with the drawback of limiting the reported results to either maximizing net benefit in regional scale models or minimizing pumping costs for localized cases. From a policy perspective, limited insight can be gained from these studies because the results are restricted to a single, efficient solution and they neglect non-market values that may influence a management decision. Conversely, economically derived objective functions tend to exhibit a plateau upon nearing the optimal value. This plateau effect, or non-uniqueness, is actually a positive feature in the behavior of groundwater systems because it demonstrates that multiple management strategies, serving numerous community preferences, may be considered while still achieving similar quantitative results. An optimization problem takes the same set of initial conditions and looks for the most efficient solution while a decision problem looks at a situation and asks for a solution that meets certain user-defined criteria. In other words, the election of an alternative course of action using a decision support system will not always result in selection of the most `optimized' alternative. To broaden the analytical toolset available for science and policy interaction, we have developed a groundwater decision support system (GWDSS) that generates a suite of management alternatives by pairing a combinatorial search algorithm with a numerical groundwater model for consideration by decision makers and stakeholders. Subject to constraints as defined by community concerns, the tabu optimization engine systematically creates hypothetical management scenarios running hundreds, and even thousands, of simulations, and then saving the best performing realizations. Results of the search are then evaluated against stakeholder preference sets using ranking methods to aid in identifying a subset of alternatives for final

  5. Engineering natural language processing solutions for structured information from clinical text: extracting sentinel events from palliative care consult letters.

    PubMed

    Barrett, Neil; Weber-Jahnke, Jens H; Thai, Vincent

    2013-01-01

    Despite a trend to formalize and codify medical information, natural language communications still play a prominent role in health care workflows, in particular when it comes to hand-overs between providers. Natural language processing (NLP) attempts to bridge the gap between informal, natural language information and coded, machine-interpretable data. This paper reports on a study that applies an advanced NLP method for the extraction of sentinel events in palliative care consult letters. Sentinel events are of interest to predict survival and trajectory for patients with acute palliative conditions. Our NLP method combines several novel characteristics, e.g., the consideration of topological knowledge structures sourced from an ontological terminology system (SNOMED CT). The method has been applied to the extraction of different types of sentinel events, including simple facts, temporal conditions, quantities, and degrees. A random selection of 215 anonymized consult letters was used for the study. The results of the NLP extraction were evaluated by comparison with coded sentinel event data captured independently by clinicians. The average accuracy of the automated extraction was 73.6%.

  6. Importance of Solvation in Understanding the Chiroptical Spectra of Natural Products in Solution Phase: Garcinia Acid Dimethyl Ester

    PubMed Central

    Polavarapu, Prasad L.; Scalmani, Giovanni; Hawkins, Edward K.; Rizzo, Carmelo; Jeirath, Neha; Ibnusaud, Ibrahim; Habel, Deenamma; Nair, Divya Sadasivan; Haleema, Simimole

    2013-01-01

    The optical rotatory dispersion (ORD), electronic circular dichroism (ECD), and vibrational circular dichroism (VCD) spectra of (+)-garcinia acid dimethyl ester have been measured and analyzed by comparison with the corresponding spectra predicted by quantum chemical methods for (2S,3S)-garcinia acid dimethyl ester. For solution-phase calculations the recently developed continuous surface charge polarizable continuum model (PCM) has been used. It is found that gas-phase predictions and PCM predictions at the B3LYP/aug-cc-pVDZ level yield nearly mirror-image ECD spectra in the 190–250 nm region for the same absolute configuration and that gas-phase ECD predictions lead to incorrect absolute configuration. At the CAM-B3LYP/aug-cc-pVDZ level, however, gas-phase predictions and PCM predictions of ECD in the 190–250 nm region are not so different, but PCM predictions provide better agreement with the experimental observations. For carbonyl stretching vibrations, the vibrational band positions predicted at the B3LYP/aug-cc-pVDZ level in gas-phase calculations differ significantly from the corresponding experimentally observed band positions, and this discrepancy has also been corrected by the use of PCM. In addition, the solution-phase VCD predictions provided better agreement (with experimental VCD observations) than gas-phase VCD predictions. These observations underscore the importance of including solvent effects in quantum chemical calculations of chiroptical spectroscopic properties. PMID:21114277

  7. Removal of ibuprofen, naproxen and carbamazepine in aqueous solution onto natural clay: equilibrium, kinetics, and thermodynamic study

    NASA Astrophysics Data System (ADS)

    Khazri, Hassen; Ghorbel-Abid, Ibtissem; Kalfat, Rafik; Trabelsi-Ayadi, Malika

    2016-04-01

    This study aimed to describe the adsorption of three pharmaceuticals compounds (ibuprofen, naproxen and carbamazepine) onto natural clay on the basis of equilibrium parameters such as a function of time, effect of pH, varying of the concentration and the temperature. Adsorption kinetic data were modeled using the Lagergren's first-order and the pseudo-second-order kinetic equations. The kinetic results of adsorption are described better using the pseudo-second order model. The isotherm results were tested in the Langmuir, Freundlich and Dubinin-Radushkevich models. The thermodynamic parameters obtained indicate that the adsorption of pharmaceuticals on the clay is a spontaneous and endothermic process.

  8. Radiation crosslinking of carboxymethylcellulose of various degree of substitution at high concentration in aqueous solutions of natural pH

    NASA Astrophysics Data System (ADS)

    Wach, Radoslaw A.; Mitomo, Hiroshi; Nagasawa, Naotsugu; Yoshii, Fumio

    2003-12-01

    Carboxymethylcellulose (CMC) hydrogel formed by ionizing radiation at highly concentrated aqueous solutions was found to undergo swelling depending on the pH of the swelling media. Swelling increases at neutral and basic pH due to ionization of carboxymethyl groups on side chains. The presence of charges develops repulsive forces between polymer chains of the network causing its expansion. Hydrogel in relaxed state as well as dried gel reveals good mechanical properties. It was considered that intermolecular crosslinking reactions occur by a radical route. Radicals placed on anhydroglucose repeating unit as well as on side chains were distinguished from ESR spectra of CMC. A stable doublet signal with 2.0 mT splitting constant belongs to a radical placed on the α-carbon atom of the substituent group, R-O- rad CH-COO -. It was assumed that this species participates in intermolecular crosslinking.

  9. Efficiency of natural and acid-activated clays in the removal of Pb(II) from aqueous solutions.

    PubMed

    Eloussaief, Mabrouk; Benzina, Mourad

    2010-06-15

    The adsorption of Pb(2+) ions onto Tunisian clay in aqueous solution was studied in a batch system. Four samples of clay (RGC, RRC, AGC, and ARC) were used. The raw RGC and RRC clays were sampled in jebel Tejera-Esghira in Medenine area (Southeast of Tunisia). AGC and ARC corresponds respectively to RGC and RRC activated by 6M sulphuric acid. The adsorbents employed were characterized by X-Ray Diffraction, chemical analysis, and the specific surface area was also estimated. The ability of clay samples to remove Pb(2+) ions from aqueous solutions has been studied at different operating conditions: temperature and pH. The optimum pH for lead ions retention was found 7.0 for the four clay samples. The effect of temperature on adsorption phenomenon was also investigated. The results indicated that adsorption is an exothermic process for lead ions removal. The equilibrium adsorption data were analysed using the Langmuir and Freundlich isotherms. The adsorption capacities (X(m)) for RRC, RGC, ARC and AGC were found 17.84, 25.44, 27.15 and 40.75 mg g(-1), respectively. The performance of the red clay after activation was compared to that of silica gel, which has maximum adsorption of 20 mg g(-1). On the other hand, although the performance of activated carbon (88.3 mg g(-1)) is by far higher than that of the green clay after activation, the latter seems to have better performance than that of the silica gel.

  10. Education in the imbalance of Nature

    NASA Astrophysics Data System (ADS)

    Shlafman, L. M.; Kontar, V. A.

    2013-12-01

    There are two concepts understanding of the real Nature: balanced and imbalanced. The traditional balanced concept understanding of Nature was originated in prehistoric times to calm the frightened souls of prehistoric man and manage groups of people. The balanced concept presupposes that Nature is isotropic, balanced, etc. The balanced concept of understanding of Nature gradually has moved to science and technology. The balanced concept of understanding of Nature is dominating from the prehistoric time up to today. But always parallel and opposite was exists the concept imbalanced understanding of Nature, which presupposes that Nature is anisotropy, imbalanced, etc. The balanced concept is much simpler than Imbalanced. The balanced concept has given mankind a lot of rough description of Nature which helped to solve a lot of practical problems but with sufficient accuracy, i.e. approximately, but not with an absolute precision. While people were few, and a lot of resources, person could take from Nature only what Nature gave willingly. During this period, people feared and respected Nature and Nature was able easily compensate the activity of people. The high accuracy of the description of Nature was not needed when resources were plentiful and people were few. But now the situation is completely different. The population has become a very large and growing. Traditional resources are almost run out and the lack of resources escalates. People are not afraid of Nature and bravely try to take by force what Nature does not give voluntarily. People invaded into imbalance Nature, and Nature can no longer compensate activity of people. The era of global change is started, including those that man provokes. In the conditions of global changes is insufficiently of the approximate solutions of the traditional balanced concept. The balanced concept is exhausted, and increasingly misleads people. The balanced concept cannot solve the problems that arise in the global change

  11. Assessing Assessment: How Use of the Concept Inventory of Natural Selection Influences the Instructional Practices of an Experienced Biology Professor and Supplemental Instruction Leader

    ERIC Educational Resources Information Center

    Vanmali, Binaben H.

    2012-01-01

    Assessment has garnered increased interest in recent years. It is seen as critical to enhancing student learning and understanding. Formative assessment tools such as concept inventories could be valuable in moving toward such goals. Concept inventories, a recent addition to biology education, hold much promise for helping faculty to understand…

  12. Mechanisms of gold recovery from aqueous solutions using a novel tannin gel adsorbent synthesized from natural condensed tannin.

    PubMed

    Ogata, Takeshi; Nakano, Yoshio

    2005-11-01

    We report a novel recovery system for gold (Au), which is one of the precious metals contained in electronic scrap, utilizing tannin gel particles. Tannin gel particles were prepared by a process of cross-linking of condensed tannin (wattle tannin), which is a ubiquitous and inexpensive natural material having many hydroxyl groups. The adsorption mechanism of gold onto tannin gel particles was elucidated: the adsorption of gold takes place through the reduction of trivalent gold ions to metallic gold on the surface of tannin gel particles, which is accompanied by the simultaneous oxidization of the hydroxyl groups of tannin gel. Additionally, the adsorption capacity of gold was found to be extremely high, 8000 mg-Au/g-dry gel. The outstanding characteristics of tannin gel particles for gold offers the possibility of efficient recovery of other precious metals.

  13. Wastewater reclamation through a combination of natural systems (infiltration-percolation and constructed wetlands): a solution for small communities.

    PubMed

    Huertas, E; Folch, M; Salgot, M

    2007-01-01

    The decision on technologies used for reclaiming wastewater appears as important as a consequence of the implications on the economic, environmental and health conditions of societies. The problem arises when deciding how to deal with wastewater in small communities, because the costs of implementing and operating small, intensive wastewater treatment plants are unacceptable and can lead to financing and operation problems. Extensive treatment systems can be a good solution, where space is available. This paper presents the combination of two soft technologies (infiltration-percolation and constructed wetlands) to treat and reclaim wastewater. The obtained results show that the infiltration-percolation effluent presents a quality enough to be reused for irrigation of industrial crops, nurseries, fodder, cereals and oleaginous seeds, ornamental flower production; industrial cooling; impoundments, water bodies, and streams for recreational use in which the public's contact with the water is not permitted; and irrigation of forested areas, landscape areas and restricted access areas. Moreover, the combination of infiltration-percolation and constructed wetlands increases the list of final reclamation to the following: irrigation of pasture for milk or meat animals, crops for canning industry, crops not raw-consumed, fruit trees except by sprinkling, aquaculture; and aquifer recharge by localised percolation through the soil.

  14. The self-assemble of natural cyclodextrins in aqueous solutions: Application of miniature permeation studies for critical aggregation concentration (cac) determinations.

    PubMed

    Saokham, Phennapha; Sá Couto, André; Ryzhakov, Alexey; Loftsson, Thorsteinn

    2016-05-30

    Permeation techniques can be applied to determine the critical aggregation concentration (cac) of natural cyclodextrins (CDs) in aqueous solutions although the method is both laborious and time consuming. In the present study, the permeation technique was modified and the influence of osmotic pressure, sampling time, CD concentration and molecular weight-cut off (MWCO) of the membrane were investigated in two different permeation units, that is Franz diffusion cells and Slide-A-Lyzer™ MINI Dialysis. While both the osmotic pressure and CD concentration affect the steady state flux in both permeation units, effects of sampling time and the MWCO of the mounted membrane were only observed in the Franz diffusion cells. The osmotic effect was negligible in the Slide-A-Lyzer™ MINI Dialysis units. The modified permeation technique using Slide-A-Lyzer™ MINI Dialysis units was then used to determine the cac of natural CDs in water. The cac of αCD, βCD and γCD was 1.19±0.17, 0.69±0.05 and 0.93±0.04% (w/v), respectively. The results indicated that the cac values depended on their intrinsic solubility. Moreover, the cac value of γCD in aqueous hydrocortisone/γCD inclusion complex solution was identical to the γCD cac value determined in pure water.

  15. Learning the Rules of the Game: The Nature of Game and Classroom Supports When Using a Concept-Integrated Digital Physics Game in the Middle School Science Classroom

    NASA Astrophysics Data System (ADS)

    Stewart, Phillip Michael, Jr.

    Games in science education is emerging as a popular topic of scholarly inquiry. The National Research Council recently published a report detailing a research agenda for games and science education entitled Learning Science Through Computer Games and Simulations (2011). The report recommends moving beyond typical proof-of-concept studies into more exploratory and theoretically-based work to determine how best to integrate games into K-12 classrooms for learning , as well as how scaffolds from within the game and from outside the game (from peers and teachers) support the learning of applicable science. This study uses a mixed-methods, quasi-experimental design with an 8th grade class at an independent school in southern Connecticut to answer the following questions: 1. What is the nature of the supports for science content learning provided by the game, the peer, and the teacher, when the game is used in a classroom setting? 2. How do the learning gains in the peer support condition compare to the solo play condition, both qualitatively and quantitatively? The concept-integrated physics game SURGE (Scaffolding Understanding through Redesigning Games for Education) was selected for this study, as it was developed with an ear towards specific learning theories and prior work on student understandings of impulse, force, and vectors. Stimulated recall interviews and video observations served as the primary sources and major patterns emerged through the triangulation of data sources and qualitative analysis in the software QSR NVivo 9. The first pattern which emerged indicated that scaffolding from within the game and outside the game requires a pause in game action to be effective, unless that scaffolding is directly useful to the player in the moment of action. The second major pattern indicated that both amount and type of prior gaming experience has somewhat complex effects on both the uses of supports and learning outcomes. In general, a high correlation was found

  16. Effects of dissolved Ca2+, Mg2+, and Na+ ions on the supramolecular aggregation of natural organic matter in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Ahn, W.; Kalinichev, A. G.; Clark, M. M.

    2008-12-01

    The complexation of natural organic matter (NOM) with metal ions, minerals and organic species in soil and water allows NOM to form water-soluble and water-insoluble aggregates of widely differing chemical and biological stabilities. Metal-NOM interaction induces strong correlations between the concentration of natural organic matter and the speciation, solubility and toxicity of many metals in the environment. In water purification and desalination, NOM is also implicated in fouling of nanofiltration and reverse osmosis membranes, either as the primary foulant or as a conditioning layer for microbial attachment ("biofouling"). In this work we investigated the effects of various metal ions on NOM aggregation in aqueous solutions, by a combination of dynamic light scattering (DLS), small angle neutron scattering (SANS) and large-scale molecular dynamics (MD) computer simulations. This allows a detailed molecular-scale statistical analysis of the size and the structural topology of metal-NOM aggregates. The DLS measurements show that Ca2+ ions present in a Suwannee River NOM (SRNOM) solution lead to the formation of a wide range of supramolecular structures with sizes between 100 and 1,000 nm. In contrast, Mg2+ and Na+ do not affect the aggregation of SRNOM as strongly. SANS data are inconclusive but indicate the presence of quite large (>50 nm) fractal particles formed presumably through a cluster-cluster aggregation. MD simulations confirm these observations and show that NOM can aggregate in aqueous solutions by two different mechanisms. On the one hand, NOM molecules can spontaneously aggregate by hydrogen bonding between their functional groups when only Na+ and Mg2+ are present as background cations. This promotes the formation of uniformly shaped NOM clusters. On the other hand, if Ca2+ ions are present in solution, they can more strongly bind two different NOM molecules by co-complexing the carboxylate groups, thus promoting the formation of longer linear and

  17. Reduced Dental Plaque Formation in Dogs Drinking a Solution Containing Natural Antimicrobial Herbal Enzymes and Organic Matcha Green Tea.

    PubMed

    Lindinger, Michael I

    2016-01-01

    The results of an exploratory, multicenter clinical study confirmed the hypothesis that a novel, natural, and safe oral care product (OCP) reduced the rate of plaque formation on teeth of dogs consuming the OCP (antimicrobial plant-derived enzymes, organic matcha green tea, cultured dextrose, sodium bicarbonate, and ascorbic acid) compared to controls. Healthy dogs without periodontitis, of varying breeds, sex, and age, were recruited and enrolled, using nonrandomized stratification methods, into a control and treatment groups. Treatment group dogs drank only water into which OCP was suspended, for 28 days. Control group dogs drank their normal household water. On day 0 all teeth were cleaned by a veterinarian and gingivitis was assessed. On days 14, 21, and 28 plaque index, plaque thickness, gingivitis, freshness of breath, and general health were assessed. Over the 28 days of study, dogs on the OCP had significant reduction in plaque index and plaque thickness compared to controls. By day 14 OCP reduced plaque formation by 37%; the 28-day reduction in plaque index and coverage averaged 22% with no measurable gingivitis or calculus. Conclusion. Using the OCP attenuated dental plaque formation when consumed as normal drinking water and in the absence of other modes of oral care.

  18. Reduced Dental Plaque Formation in Dogs Drinking a Solution Containing Natural Antimicrobial Herbal Enzymes and Organic Matcha Green Tea

    PubMed Central

    2016-01-01

    The results of an exploratory, multicenter clinical study confirmed the hypothesis that a novel, natural, and safe oral care product (OCP) reduced the rate of plaque formation on teeth of dogs consuming the OCP (antimicrobial plant-derived enzymes, organic matcha green tea, cultured dextrose, sodium bicarbonate, and ascorbic acid) compared to controls. Healthy dogs without periodontitis, of varying breeds, sex, and age, were recruited and enrolled, using nonrandomized stratification methods, into a control and treatment groups. Treatment group dogs drank only water into which OCP was suspended, for 28 days. Control group dogs drank their normal household water. On day 0 all teeth were cleaned by a veterinarian and gingivitis was assessed. On days 14, 21, and 28 plaque index, plaque thickness, gingivitis, freshness of breath, and general health were assessed. Over the 28 days of study, dogs on the OCP had significant reduction in plaque index and plaque thickness compared to controls. By day 14 OCP reduced plaque formation by 37%; the 28-day reduction in plaque index and coverage averaged 22% with no measurable gingivitis or calculus. Conclusion. Using the OCP attenuated dental plaque formation when consumed as normal drinking water and in the absence of other modes of oral care. PMID:27867678

  19. Cyclic growth and branching phenomena of calcite grown in Mg(2+) containing solutions and in natural systems

    NASA Astrophysics Data System (ADS)

    Wiethoff, Felix; Richter, Detlef K.; Neuser, Rolf D.; Immenhauser, Adrian; Gies, Hermann; Schreuer, Jürgen

    2016-04-01

    Undulosity in calcites (radiaxial fibrous calcite (RFC) and fascicular-optic fibrous calcite (FOFC)) is a common phenomenon in paleozoic and mesozoic limestones. Despite their importance as archives for climate reconstruction the underlying mechanisms and processes of their formation are still poorly understood [1]. To improve the application of such archives for climate reconstruction a better knowledge of their formation and possible alteration scenarios is necessary. In Mg2+ containing gel based growth experiments calcite crystals develop pathological morphologies. The morphology can be described as a product of a geometrical selective branching process at the rhombohedral crystal faces. Multiple sheet like building blocks evolve at the branching crystal face; each slightly tilted in respect to their substrate. The product is a crystal aggregate consisting out of several misoriented sub domains. In polarized light thin section microscopy the extinction behaviour of these sub units resemble the optical undulosity of radiaxial fibrous cements. In a multi method approach the local Mg2+ concentration was measured using EMPA and compared with maps of the local crystal orientation (via electron backscatter diffraction (EBSD)) and thin section microscopy. We found that Mg2+ is enriched at the sub-domain boundaries and deduced that lattice misfit as a consequence of impurity incorporation causes the crystal branching. We propose that this process is cyclic and each new misoriented sheet represents a growth period after a phase of inhibited growth caused by crystal faces covered by Mg2+-ions. In comparison to natural systems we found that radiaxial-fibrous cave cements show a pathological morphology based on the same formation principles. [1] Richter et al. (2011) Sediment. Geol. 239, 23-36 [2] Reeder & Paquette (1989) Sediment. Geol. 65, 239-247 [3] Davis et al. (2004) Am. Min. 89, 714-720

  20. Modelling of the acid-base properties of natural and synthetic adsorbent materials used for heavy metal removal from aqueous solutions.

    PubMed

    Pagnanelli, Francesca; Vegliò, Francesco; Toro, Luigi

    2004-02-01

    In this paper a comparison about kinetic behaviour, acid-base properties and copper removal capacities was carried out between two different adsorbent materials used for heavy metal removal from aqueous solutions: an aminodiacetic chelating resin as commercial product (Lewatit TP207) and a lyophilised bacterial biomass of Sphaerotilus natans. The acid-base properties of a S. natans cell suspension were well described by simplified mechanistic models without electrostatic corrections considering two kinds of weakly acidic active sites. In particular the introduction of two-peak distribution function for the proton affinity constants allows a better representation of the experimental data reproducing the site heterogeneity. A priori knowledge about resin functional groups (aminodiacetic groups) is the base for preliminary simulations of titration curve assuming a Donnan gel structure for the resin phase considered as a concentrated aqueous solution of aminodiacetic acid (ADA). Departures from experimental and simulated data can be interpreted by considering the heterogeneity of the functional groups and the effect of ionic concentration in the resin phase. Two-site continuous model describes adequately the experimental data. Moreover the values of apparent protonation constants (as adjustable parameters found by non-linear regression) are very near to the apparent constants evaluated by a Donnan model assuming the intrinsic constants in resin phase equal to the equilibrium constants in aqueous solution of ADA and considering the amphoteric nature of active sites for the evaluation of counter-ion concentration in the resin phase. Copper removal outlined the strong affinity of the active groups of the resin for this ion in solution compared to the S. natans biomass according to the complexation constants between aminodiacetic and mono-carboxylic groups and copper ions.

  1. Core Concepts of Kinesiology.

    ERIC Educational Resources Information Center

    Hudson, Jackie L.

    1995-01-01

    Core concepts of kinesiology are the basis of communication about movement that facilitate progression of skill levels. The article defines and exemplifies each of 10 core concepts: range of motion, speed of motion, number of segments, nature of segments, balance, coordination, compactness, extension at release/contact, path of projection, and…

  2. Experimental Study on Thermal-Hydraulics During Start-Up in the Natural Circulation Boiling Water Reactor Concept: Effects of System Pressure and Increasing Heat Flux on the Geysering and Density Wave Oscillation

    SciTech Connect

    Hadid Subki, M.; Masanori Aritomi; Noriyuki Watanabe; Chaiwat Muncharoen

    2002-07-01

    The feasibility study in thermal-hydraulics for the future light water reactor concept is carried out. One of the essential studies is the two-phase flow instability during start-up in the natural circulation boiling water reactor (BWR) concept. It is anticipated that the occurrence of the two-phase flow instabilities during start-up significantly affects the feasibility concept, since it would cause the complexity in raising and maneuvering the power output. The purpose of the current study is to experimentally investigate the driving mechanism of the geysering and density wave oscillation in the natural circulation loop, induced by a range of system operating pressure and increasing heat flux in vertical parallel channels. The pressure range of atmospheric up to about 4 bars, and the input heat flux range of 0 up to 577 kW/m{sup 2} are applied in these experiments. An experimental apparatus of twin boiling upflow channels to simulate natural circulation flow loop has been designed, constructed and operated. The natural circulation in the loop occurs due to the density difference between two-phase region in the channels and the single-phase liquid in the downcomer. The objective of the study is to propose a rational start-up procedure in which the geysering and density wave oscillation can be prevented during startup, according to its system pressure and heat flux. Previous studies have clarified that three (3) kinds of thermo-hydraulics instabilities may occur during start-up in the natural circulation BWR depending on its procedure and reactor configuration, which are (1) geysering induced by condensation, (2) natural circulation induced by hydrostatic head fluctuation in steam separator, and (3) density wave oscillation. (authors)

  3. Command and Control Concepts and Solutions for Major Events Safety and Security: Lessons Learned from the Canadian Experience with Vancouver 2010 and G8/G20 Events

    DTIC Science & Technology

    2011-06-01

    This activity involved science and technology (S&T) support for performing ergonomic analysis and workspace design for ISU operations and command...designed and implement a CIS dashboard which was used for daily commander’s briefs. The SharePoint solution is a legacy that was transitioned to JTFP

  4. RADIOCHEMICAL PURITY OF MO AND TC SOLUTION OBTAINED AFTER IRRADIATION AND DISSOLUTION OF MO-100-ENRICHED AND ULTRA-HIGH-PURITY NATURAL MO DISKS

    SciTech Connect

    Tkac, Peter; Gromov, Roman; Chemerisov, Sergey D.; Rotsch, David A.; Vandegrift, George F.

    2016-09-01

    Four irradiations of ultra-high-purity natural Mo targets and one irradiation using 97.4% Mo-100-enriched material were performed. The purpose of these irradiations was to determine whether the presence of Sn stabilizer in the H2O2 used for the dissolution of sintered Mo disks can affect the radiochemical purity of the final K2MoO4 in 5M KOH solution. Results from radiochemical purity tests performed using thin-layer paper chromatography show that even 2– 3× excess of Sn-stabilized H2O2 typically used for dissolution of sintered Mo disks did not affect the radiochemical purity of the final product.

  5. Effects of various competing ligands on the kinetics of trace metal complexes of Laurentian Fulvic Acid in model solutions and natural waters.

    PubMed

    Yapici, Tahir; Fasfous, Ismail I; Zhao, Jiujiang; Chakrabarti, Chuni L

    2009-03-16

    The objective of this work was to study the effects of the following Ligands: Chelex-100, Dowex MAC-3 and Dowex 50WX-8 using Competing Ligand Exchange Method. This objective was achieved by investigating complex dissociation kinetics of trace metals: Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Mn(II) and Pb(II) of a well-characterized Laurentian Fulvic Acid (LFA) in model solutions and in a natural waters of Lake Heva (Québec, Canada). The effects of variation in the competing ligands (including their quantities) on the complex dissociation kinetics were quantitatively characterized by their first-order dissociation rate coefficients. The kinetic lability of the metal complexes varied with the metal-to-LFA ratio, as expected from the theory of metal complexes of the chemically and physically heterogeneous complexants, LFA. The general trend in the metal-binding by the above competing ligands was: Dowex 50WX-8>Chelex-100>Dowex MAC-3. However, no difference was found between the Dowex 50WX-8 and Chelex-100 for Cd(II), Zn(II), and Co(II). The results revealed the importance of the quantity of Chelex-100 as a competing ligand in the metal(II)-LFA complexation, on the dissociation kinetics of these complexes in model solutions. By developing Competing Ligand Exchange Method as an analytical technique, for studying the relative affinities of the above competing ligands for metals complexation in natural waters this work has made a substantial contribution to analytical chemistry.

  6. Removal of nickel(II) ions from aqueous solutions using the natural clinoptilolite and preparation of nano-NiO on the exhausted clinoptilolite

    NASA Astrophysics Data System (ADS)

    Rajic, Nevenka; Stojakovic, Djordje; Jovanovic, Mina; Logar, Natasa Zabukovec; Mazaj, Matjaz; Kaucic, Venceslav

    2010-12-01

    The natural zeolite tuff (clinoptilolite) from a Serbian deposit has been studied as adsorbent for Ni(II) ions from aqueous solutions. Its sorption capacity at 298 K varies from 1.9 mg Ni g -1 (for the initial solution concentration of 100 mg Ni dm -3) to 3.8 mg Ni g -1 (for C0 = 600 mg Ni dm -3) and it increases 3 times at 338 K. The sorption is best described by the Sips isotherm model. The sorption kinetics follows the pseudo-second-order model, the activation energies being 7.44, 5.86, 6.62 and 6.63 kJ mol -1 for C0 = 100, 200, 300 and 400 mg Ni dm -3, respectively. The sorption involves a film diffusion, an intra-particle diffusion, and a chemical cation-exchange between the Na + ions of clinoptilolite and the Ni 2+ ions. The sorption is endothermic (Δ H° being 37.9, 33.4, 30.0, 27.7 and 24.3 kJ mol -1 for C0 = 100, 200, 300, 400 and 600 mg Ni dm -3, respectively) and spontaneous in the 298-338 K temperature range. Thermal treatment of the Ni(II)-loaded clinoptilolite results in the formation of spherical nano-NiO particles of approx. 5 nm in diameter which are randomly dispersed in the clinoptilolite lattice.

  7. The Insidious Nature of 'Hard-Core' Alternative Conceptions: Implications for the constructivist research programme of patterns in high school students' and pre-service teachers' thinking about ionisation energy

    NASA Astrophysics Data System (ADS)

    Taber, Keith S.; Tan, Kim Chwee Daniel

    2011-01-01

    The present study contributes to the constructivist research programme (RP) into learning science by comparing patterns in responses from two groups of learners-senior high school students and pre-service teachers-in the same educational context (Singapore), to a diagnostic instrument relating to the topic of ionisation energies. This topic is currently included in the curriculum for 16- to 19-year-old students studying chemistry in Singapore (and elsewhere). The comparison shows that: (1) although graduate pre-service teachers offered some types of incorrect responses less frequently than high school students; (2) they retained high levels of alternative conceptions commonly found among high school students; and (3) of particular note, certain alternative conceptions were found to be more common among the graduates. This suggests the intuitive appeal of certain alternative conceptions is such that they can readily be reproduced down 'generations' of learners. The findings are explored in terms of a range of conceptual resources that have been developed within the constructivist RP. The analysis suggests that the curriculum sets out inappropriate target knowledge for senior high school students, given the nature of the subject matter and the prior learning of the students. It is also suggested that it may be fruitful to consider conceptual learning in terms analogous to the RP found in science, and that from this perspective certain insidious alternative conceptions can be understood as derived from commitments that are taken for granted and protected from explicit challenge by a protective belt of refutable auxiliary conceptions.

  8. Fe hydroxyphosphate precipitation and Fe(II) oxidation kinetics upon aeration of Fe(II) and phosphate-containing synthetic and natural solutions

    NASA Astrophysics Data System (ADS)

    van der Grift, B.; Behrends, T.; Osté, L. A.; Schot, P. P.; Wassen, M. J.; Griffioen, J.

    2016-08-01

    Exfiltration of anoxic Fe-rich groundwater into surface water and the concomitant oxidative precipitation of Fe are important processes controlling the transport of phosphate (PO4) from agricultural areas to aquatic systems. Here, we explored the relationship between solution composition, reaction kinetics, and the characteristics of the produced Fe hydroxyphosphate precipitates in a series of aeration experiments with anoxic synthetic water and natural groundwater. A pH stat device was used to maintain constant pH and to record the H+ production during Fe(II) oxidation in the aeration experiments in which the initial aqueous P/Fe ratios ((P/Fe)ini), oxygen concentration and pH were varied. In general, Fe(II) oxidation proceeded slower in the presence of PO4 but the decrease of the PO4 concentration during Fe(II) oxidation due to the formation of Fe hydroxyphosphates caused additional deceleration of the reaction rate. The progress of the reaction could be described using a pseudo-second-order rate law with first-order dependencies on PO4 and Fe(II) concentrations. After PO4 depletion, the Fe(II) oxidation rates increased again and the kinetics followed a pseudo-first-order rate law. The first-order rate constants after PO4 depletion, however, were lower compared to the Fe(II) oxidation in a PO4-free solution. Hence, the initially formed Fe hydroxyphosphates also affect the kinetics of continuing Fe(II) oxidation after PO4 depletion. Presence of aqueous PO4 during oxidation of Fe(II) led to the formation of Fe hydroxyphosphates. The P/Fe ratios of the precipitates ((P/Fe)ppt) and the recorded ratio of H+ production over decrease in dissolved Fe(II) did not change detectably throughout the reaction despite a changing P/Fe ratio in the solution. When (P/Fe)ini was 0.9, precipitates with a (P/Fe)ppt ratio of about 0.6 were formed. In experiments with (P/Fe)ini ratios below 0.6, the (P/Fe)ppt decreased with decreasing (P/Fe)ini and pH value. Aeration experiments with

  9. The Concept of "Teachability."

    ERIC Educational Resources Information Center

    Tubbs, Nigel

    2003-01-01

    Asserts that "teachability" is a speculative concept that has for its form and content the absolute, suggesting that its dialectical movement and speculative significance are mis-recognized when the illusionary nature of its constitutive moments is suppressed. The essay outlines the speculative nature of the master/slave relationship in Hegel's…

  10. Concept Mapping

    PubMed Central

    Brennan, Laura K.; Brownson, Ross C.; Kelly, Cheryl; Ivey, Melissa K.; Leviton, Laura C.

    2016-01-01

    Background From 2003 to 2008, 25 cross-sector, multidisciplinary community partnerships funded through the Active Living by Design (ALbD) national program designed, planned, and implemented policy and environmental changes, with complementary programs and promotions. This paper describes the use of concept-mapping methods to gain insights into promising active living intervention strategies based on the collective experience of community representatives implementing ALbD initiatives. Methods Using Concept Systems software, community representatives (n=43) anonymously generated actions and changes in their communities to support active living (183 original statements, 79 condensed statements). Next, respondents (n=26, from 23 partnerships) sorted the 79 statements into self-created categories, or active living intervention approaches. Respondents then rated statements based on their perceptions of the most important strategies for creating community changes (n=25, from 22 partnerships) and increasing community rates of physical activity (n=23, from 20 partnerships). Cluster analysis and multidimensional scaling were used to describe data patterns. Results ALbD community partnerships identified three active living intervention approaches with the greatest perceived importance to create community change and increase population levels of physical activity: changes to the built and natural environment, partnership and collaboration efforts, and land-use and transportation policies. The relative importance of intervention approaches varied according to subgroups of partnerships working with different populations. Conclusions Decision makers, practitioners, and community residents can incorporate what has been learned from the 25 community partnerships to prioritize active living policy, physical project, promotional, and programmatic strategies for work in different populations and settings. PMID:23079266

  11. CONCEPT IDENTIFICATION AS A FUNCTION OF INSTRUCTIONS, LABELS, SEQUENCE, CONCEPT TYPE, AND TEST ITEM TYPE.

    ERIC Educational Resources Information Center

    LYNCH, DANIEL O.

    THE EFFECTS OF INSTRUCTIONS, TYPE OF LABEL, TYPE OF CONCEPT, AND SEQUENCE OF CONCEPTS BY TYPE UPON CONCEPT IDENTIFICATION WERE INVESTIGATED IN THIS STUDY. PERFORMANCE WAS ANALYZED IN TERMS OF FOUR TYPES OF TEST ITEMS. INSTRUCTION, FOCUSING ON THE CONCEPT TO BE ATTAINED AND THE CONCEPT NATURE, WAS FOUND TO FACILITATE CONCEPT IDENTIFICATION…

  12. Geochemical processes and the effects of natural organic solutes on the solubility of selenium in coal-mine backfill samples from the Powder River basin, Wyoming

    USGS Publications Warehouse

    See, R.B.; Reddy, K.J.; Vance, G.F.; Fadlelmawla, A.A.; Blaylock, M.J.

    1995-01-01

    Geochemical processes and the effects of natural organic solutes on the solubility of selenium in coal-mine backfill aquifers were investigated. Backfill and ground-water samples were collected at coal mines in the Powder River Basin, Wyoming. Backfill was generally dominated by aluminum (14,400 to 49,000 mg/kg (milligrams per kilogram)), iron (3,330 to 23,200 mg/kg), and potassium (7,950 to 18,000 mg/kg). Backfill saturated-paste selenium concentrations ranged from 1 to 156 mg/kg (microsiemens per kilogram). Ground-water total selenium concentrations ranged from 3 to 125 mg/L. Dissolved organic carbon in all ground-water samples was dominated by hydrophobic and hydrophilic acids (38 to 84 percent). Selenite sorption/desorption experiments were conducted using background solutions of distilled-deionized water, 0.1 molar calcium chloride, and isolated hydrophobic and hydrophilic acids. Selenite sorption was larger when 0.1 molar calcium chloride was used. The addition of hydrophilic acid decreased selenite sorption more than the addition of hydrophobic acids. Geochemical modelling was used to predict the solid phases controlling dissolved selenium concentrations and to evaluate the effects of dissolved organic carbon on selenium solubility. Results suggested that 55 to 90 percent of selenium in backfill precipitation/dissolution extracts was dominated by magnesium selenate ion pairs. Dissolved organic carbon had little effect on selenium speciation. A redox chamber was constructed to control Eh and pH in water and backfill-core sample suspensions. The response of selenite and selenate in water samples to redox conditions did not follow thermodynamic predictions. Reduction of selenate in water samples did not occur at any of the redox levels tested.

  13. Efficacy and safety of imidacloprid/moxidectin spot-on solution and fenbendazole in the treatment of dogs naturally infected with Angiostrongylus vasorum (Baillet, 1866).

    PubMed

    Willesen, J L; Kristensen, A T; Jensen, A L; Heine, J; Koch, J

    2007-07-20

    A randomized, blinded, controlled multicentre field trial study was conducted to evaluate the efficacy and safety of imidacloprid 10%/moxidectin 2.5% spot-on solution and fenbendazole in treating dogs naturally infected with Angiostrongylus vasorum. Dogs were randomly treated either with a single dose of 0.1 ml/kg bodyweight of imidacloprid 10%/moxidectin 2.5% spot-on solution or with 25 mg/kg bodyweight fenbendazole per os for 20 days. The study period was 42 days with dogs being examined on days 0, 7 and 42. The primary efficacy parameter was the presence of L1 larvae in faecal samples evaluated by a Baermann test from three consecutive days. Thoracic radiographs performed on each visit were being taken as a paraclinical parameter to support the results of the Baermann test. Twenty-seven dogs in the imidacloprid/moxidectin group and 23 dogs in the fenbendazole group completed the study according to protocol. The efficacies of the two treatment protocols were 85.2% (imidacloprid/moxidectin) and 91.3% (fenbendazole) with no significant difference between treatment groups. On radiographic evaluation pulmonary parenchyma showed similar improvement in each group. No serious adverse effects to treatment were recorded: most of the minor adverse effects were gastrointestinal such as diarrhea (nine dogs), vomitus (eight dogs) and salivation (three dogs). In general, these adverse effects were of short duration (1-2 days) within the first few days after treatment start and required little or no treatment. This prospective study demonstrates that both treatment protocols used are efficacious under field conditions, that treatment of mildly to moderately infected dogs with either of these protocols is safe and yields an excellent prognosis for recovering from the infection.

  14. The Lexicography of Scholarly Concepts.

    ERIC Educational Resources Information Center

    McInnis, Raymond G.

    1995-01-01

    Discusses the function of concepts in scholarly discourse. Topics include the genesis of Greenwood Press's concept dictionaries; the origins of modern rhetoric; the prescriptive nature of meaning in scholarly discourse; conceptual change, including logical positivism, introspection, and historicism; and interdisciplinary application of concepts.…

  15. Polyacrylamido-2-methyl-1-propane sulfonic acid-grafted-natural rubber as bio-adsorbent for heavy metal removal from aqueous standard solution and industrial wastewater.

    PubMed

    Phetphaisit, Chor Wayakron; Yuanyang, Siriwan; Chaiyasith, Wipharat Chuachuad

    2016-01-15

    Bio-adsorbent modified natural rubber (modified NR) was prepared, by placing the sulfonic acid functional group on the isoprene chain. This modification was carried out with the aim to prepare material capable to remove heavy metals from aqueous solution. The structures of modified NR materials were characterized by FT-IR and NMR spectroscopies. Thermal gravimetric analysis of modified NR showed that the initial degradation temperature of rubber decreases with increasing amount of polyacrylamido-2-methyl-1-propane sulfonic acid (PAMPS) in the structure. In addition, water uptake of the rubber based materials was studied as a function of time and content of PAMPS. The influence of the amount of PAMPS grafted onto NR, time, pH, concentration of metal ions, temperature, and regeneration were studied in terms of their influence on the adsorption of heavy metals (Pb(2+), Cd(2+) and Cu(2+)). The adsorption isotherms of Pb(2+) and Cd(2+) were fitted to the Freundlich isotherm model, while Cu(2+) was fitted to the Langmuir isotherm. However, the results from these two isotherms resulted in a similar behavior. The adsorption capacity of the modified NR for the various heavy metals was in the following order: Pb(2+)∼Cd(2+)>Cu(2+). The maximum adsorption capacities of Pb(2+), Cd(2+), and Cu(2+) were 272.7, 267.2, and 89.7 mg/g of modified rubber, respectively. Moreover, the modified natural rubber was used for the removal of metal ions in real samples of industrial effluents where the efficiency and regeneration were also investigated.

  16. Electrochemical degradation of PAH compounds in process water: a kinetic study on model solutions and a proof of concept study on runoff water from harbour sediment purification.

    PubMed

    Muff, J; Søgaard, E G

    2010-01-01

    The present study has investigated the possibility to apply electrochemical oxidation in the treatment of polycyclic aromatic hydrocarbon (PAHs) pollutants in water. The reaction kinetics of naphthalene, fluoranthene, and pyrene oxidation have been studied in a batch recirculation experimental setup applying a commercial one-compartment cell of tubular design with Ti/Pt(90)-Ir(10) anode. The rate of oxidation has been evaluated upon variations in current density, electrolyte composition and concentration. All three PAHs were degraded by direct anodic oxidation in 0.10 M Na(2)SO(4) electrolyte, and the removal rates were significantly enhanced by a factor of two to six in 0.10 M NaCl due to contribution from the indirect hypochlorite oxidation. Second order reaction kinetics was observed for the degradation of naphthalene in all electrolytes whereas fluoranthene and pyrene followed first order kinetics. Decreased current densities from 200 to 15 mA cm(-2) in the NaCl electrolyte also decreased the removal rates, but significantly enhanced the current efficiencies of the PAH oxidation, based on a defined current efficiency constant, k(q). This observation is believed to be due to the suppression of the water oxidation side reaction at lower applied voltages. A proof of concept study in real polluted water demonstrated the applicability of the electrochemical oxidation technique for larger scale use, where especially the indirect chloride mediated oxidation approach was a promising technique. However, the risk and extent of by-product formation needs to be studied in greater detail.

  17. Removal of Bisphenol A aqueous solution using surfactant-modified natural zeolite: Taguchi's experimental design, adsorption kinetic, equilibrium and thermodynamic study.

    PubMed

    Genç, Nevim; Kılıçoğlu, Ödül; Narci, Ali Oğuzhan

    2017-02-01

    In this study, surfactant-modified natural zeolite was used to remove Bisphenol A (BPA) from aqueous solutions. Kinetics, equilibrium and thermodynamics of BPA adsorption on the adsorbent surfaces were investigated. The experimental data were described with the Temkin isotherm and the pseudo-second- order kinetic model. Taguchi's robust design approach was used to optimize adsorption of BPA. Experimentation was planned as per Taguchi's L27 orthogonal array. Tests were conducted with different adsorbate amount, pH, time, initial concentration of BPA, temperature and agitation speed. The optimum levels of control factors for maximum total organic carbon removal were defined (adsorbate amount at 0.25 g, pH at 7, time at 30 min, initial concentration of BPA at 50 mg/L, temperature at 30°C and agitation speed at 200 rpm). The ANOVA analysis shown that the most effective control factor is adsorbent dosage; its contribution is 56.4%. Contribution of pH and mixing rate are 7.5% and 7.6%, respectively. A confirmation experiment was conducted to verify the feasibility and effectiveness of the optimal combination. The observed value of S/N (ηobs = 39) ratio is compared with that of the predicted value (ηopt = 48). The prediction error, that is, ηopt - ηobs = 9, is within CI value.

  18. Efficacy and Safety of a Permethrin-Fipronil Spot-On Solution (Effitix®) in Dogs Naturally Infested by Ticks in Europe

    PubMed Central

    Bonneau, Stéphane

    2016-01-01

    Effitix is a new broad spectrum product based on the combination of fipronil 6.1% and permethrin 54.5% in a solution for spot-on application. It has been shown to be safe and efficacious in dogs in controlling tick, flea, sandfly, and mosquito infestations in laboratory conditions. The aim of this controlled, randomised study was to assess its safety and efficacy against natural tick infestations in field conditions. One hundred eighty-two privately owned dogs were included in France and Germany: 123 dogs were treated on day 0 with the permethrin-fipronil combination (Effitix) and 59 with a permethrin-imidacloprid combination (Advantix®). Tick counts were conducted on days 0 (before treatment), 7, 14, 21, and 28. The percentages of efficacy on days 7, 14, 21, and 28 were, respectively, 91.2%, 97%, 98.3%, and 96.7% with Effitix and were 94.8%, 96.9%, 95.7%, and 94.6% with Advantix. Very few adverse events were reported. Most were not serious and/or not related to the treatment with pruritus being the most common. One administration of Effitix was highly effective and safe to treat and control tick infestations for four weeks in field conditions and had a similar efficacy as the permethrin-imidacloprid combination for all visits. PMID:27703984

  19. New insights on the nature of the chemical species involved during the process of dopamine deprotonation in aqueous solution: theoretical and experimental study.

    PubMed

    Corona-Avendaño, Silvia; Alarcón-Angeles, Georgina; Rosquete-Pina, Giselle A; Rojas-Hernández, Alberto; Gutierrez, Atilano; Ramírez-Silva, M Teresa; Romero-Romo, Mario; Palomar-Pardavé, Manuel

    2007-02-22

    Due to dopamine's chemical structure and the fact that it has three pKa values, its deprotonation process, in aqueous solution, may involve different chemical species. For instance, the first deprotonation step, from the fully protonated dopamine molecule (H3DA+) to the neutral one (H2DA), will result in zwitterionic species if a proton from one of the OH groups in the catechol ring is lost or into a neutral species if the proton is lost from the amino group. Given that the interaction of such a product with its environment will be quite different depending on its nature, it is very important, therefore, to have an accurate knowledge of which is the dopamine chemical species that results after each deprotonation step. In order to gain a better understanding of dopamine chemistry and to establish a plausible dopamine deprotonation pathway, the optimized geometries of the aforementioned species were calculated in this work by means of the density functionals theory (B3LYP/6-311+G(d,p)) in both cases: in vacuo and with solvent effect, to assess, among other theoretical criteria, the proton affinities of the different dopamine species. This permitted us to propose the following reaction pathway: [reaction in text]. Moreover, the calculations of the chemical shift (NMR-GIAO) modeling the effect of the solvent with a continuum method (PCM) was in agreement with the 13C NMR experimental spectra, which confirmed even further the proposed deprotonation pathway.

  20. Efficacy and Safety of a Permethrin-Fipronil Spot-On Solution (Effitix®) in Dogs Naturally Infested by Ticks in Europe.

    PubMed

    Navarro, Christelle; Reymond, Nadège; Crastes, Nolwenn; Bonneau, Stéphane

    2016-01-01

    Effitix is a new broad spectrum product based on the combination of fipronil 6.1% and permethrin 54.5% in a solution for spot-on application. It has been shown to be safe and efficacious in dogs in controlling tick, flea, sandfly, and mosquito infestations in laboratory conditions. The aim of this controlled, randomised study was to assess its safety and efficacy against natural tick infestations in field conditions. One hundred eighty-two privately owned dogs were included in France and Germany: 123 dogs were treated on day 0 with the permethrin-fipronil combination (Effitix) and 59 with a permethrin-imidacloprid combination (Advantix®). Tick counts were conducted on days 0 (before treatment), 7, 14, 21, and 28. The percentages of efficacy on days 7, 14, 21, and 28 were, respectively, 91.2%, 97%, 98.3%, and 96.7% with Effitix and were 94.8%, 96.9%, 95.7%, and 94.6% with Advantix. Very few adverse events were reported. Most were not serious and/or not related to the treatment with pruritus being the most common. One administration of Effitix was highly effective and safe to treat and control tick infestations for four weeks in field conditions and had a similar efficacy as the permethrin-imidacloprid combination for all visits.

  1. Reactive extraction of citric acid using tri-n-octylamine in nontoxic natural diluents: part 1--equilibrium studies from aqueous solutions.

    PubMed

    Keshav, Amit; Norge, Prakriti; Wasewar, Kailas L

    2012-05-01

    Use of cheap, nontoxic, and selective solvents could economically provide a solution to the recovery of carboxylic acids produced by the bioroute. In this regard in the present paper, reactive extraction of citric acid was studied. Problems encompassing the recovery of the acid ([H(3)A](aq)(o) = 0.1-0.8) was solved by using tertiary amine (tri-n-octylamine, TOA) in natural diluents (rice bran oil, sunflower oil, soybean oil, and sesame oil). TOA was very effective in removal of acid providing distribution coefficient (D) as high as 18.51 (E% = 95%), 12.82 (E% = 93%), 15.09 (E% = 94%), and 16.28 (E% = 94%) when used with rice bran oil, sunflower oil, soybean oil, and sesame oil, respectively. Overall extraction constants and association numbers for TOA + rice bran oil, TOA + sunflower oil, TOA + soybean oil, and TOA + sesame oil were evaluated to be 35.48 (mol/l)(-1.46), 29.79 (mol/l)(-1.30), 33.79 (mol/l)(-1.51), and 37.64 (mol/l)(-1.65) and 1.46, 1.30, 1.51, and 1.65, respectively. Specific equilibrium complexation constants (K (E(n/m))) were also predicted using mathematical modeling.

  2. Proof of Concept Assessment for the Use of Natural Language Processing to Maintain and Update the DoD Technologies Knowledge Base (DTKB)

    DTIC Science & Technology

    In 2013 the sponsor asked the Institute for Defense Analyses (IDA) to conduct a study regarding possible courses of action in order to answer an...the results obtained pertaining to the use of natural language processing (NLP) technologies to maintain and update a future DTKB.

  3. Effects of Jigsaw Cooperative Learning and Animation Techniques on Students' Understanding of Chemical Bonding and Their Conceptions of the Particulate Nature of Matter

    ERIC Educational Resources Information Center

    Karacop, Ataman; Doymus, Kemal

    2013-01-01

    The aim of this study was to determine the effect of jigsaw cooperative learning and computer animation techniques on academic achievements of first year university students attending classes in which the unit of chemical bonding is taught within the general chemistry course and these students' learning of the particulate nature of matter of this…

  4. A modular framework for biomedical concept recognition

    PubMed Central

    2013-01-01

    Background Concept recognition is an essential task in biomedical information extraction, presenting several complex and unsolved challenges. The development of such solutions is typically performed in an ad-hoc manner or using general information extraction frameworks, which are not optimized for the biomedical domain and normally require the integration of complex external libraries and/or the development of custom tools. Results This article presents Neji, an open source framework optimized for biomedical concept recognition built around four key characteristics: modularity, scalability, speed, and usability. It integrates modules for biomedical natural language processing, such as sentence splitting, tokenization, lemmatization, part-of-speech tagging, chunking and dependency parsing. Concept recognition is provided through dictionary matching and machine learning with normalization methods. Neji also integrates an innovative concept tree implementation, supporting overlapped concept names and respective disambiguation techniques. The most popular input and output formats, namely Pubmed XML, IeXML, CoNLL and A1, are also supported. On top of the built-in functionalities, developers and researchers can implement new processing modules or pipelines, or use the provided command-line interface tool to build their own solutions, applying the most appropriate techniques to identify heterogeneous biomedical concepts. Neji was evaluated against three gold standard corpora with heterogeneous biomedical concepts (CRAFT, AnEM and NCBI disease corpus), achieving high performance results on named entity recognition (F1-measure for overlap matching: species 95%, cell 92%, cellular components 83%, gene and proteins 76%, chemicals 65%, biological processes and molecular functions 63%, disorders 85%, and anatomical entities 82%) and on entity normalization (F1-measure for overlap name matching and correct identifier included in the returned list of identifiers: species 88

  5. Teachers' conceptions of the nature of science: Analyzing the impact of a teacher enhancement program in changing attitudes and perceptions of science and scientific research

    NASA Astrophysics Data System (ADS)

    Govett, Aimee Lee

    The purpose of this study was to determine the efficacy of a residential science research experience in changing participants' attitudes and understanding of the nature of science and their view of themselves as science researchers. Data from interviews, journal writings, classroom observations and two pre-post instruments were used in the evaluation plan. As participants of this study, 16 inservice teachers (K--16) attended a two-week residential institute at the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virginia. The format of the institute featured a scientific research experience designed to arm its participants with the skills needed to model their classroom teaching after scientific research. The program included lessons on the fundamentals of radio astronomy, science talks and interactions with practicing scientists, in-depth tours of the NRAO facilities, and pedagogical instruction for implementing research in the classroom. The WVU College of Education staff and the NRAO staff stressed the importance of the nature of the research experience offered to these teachers. In the Education Sessions the WVU science education staff guided participants through the steps required to turn their experience around, in order to develop student research projects for their classrooms. The results from the Research Self Assessment instrument show significant gains for all participants in being more comfortable doing research. For the Nature of Science and Science Teaching instrument there were only three items that showed significant gains for all participants both in understanding the nature of science and in their views on implementing the Green Bank constructivist learning philosophy. The women, especially the elementary teacher group, showed the greatest change in their understanding of the nature of science as reflected in the interviews as well as in their personal journals. The seven men, who were all in the secondary field, made no significant

  6. Effects of Jigsaw Cooperative Learning and Animation Techniques on Students' Understanding of Chemical Bonding and Their Conceptions of the Particulate Nature of Matter

    NASA Astrophysics Data System (ADS)

    Karacop, Ataman; Doymus, Kemal

    2013-04-01

    The aim of this study was to determine the effect of jigsaw cooperative learning and computer animation techniques on academic achievements of first year university students attending classes in which the unit of chemical bonding is taught within the general chemistry course and these students' learning of the particulate nature of matter of this unit. The sample of this study consisted of 115 first-year science education students who attended the classes in which the unit of chemical bonding was taught in a university faculty of education during the 2009-2010 academic year. The data collection instruments used were the Test of Scientific Reasoning, the Purdue Spatial Visualization Test: Rotations, the Chemical Bonding Academic Achievement Test, and the Particulate Nature of Matter Test in Chemical Bonding (CbPNMT). The study was carried out in three different groups. One of the groups was randomly assigned to the jigsaw group, the second was assigned to the animation group (AG), and the third was assigned to the control group, in which the traditional teaching method was applied. The data obtained with the instruments were evaluated using descriptive statistics, one-way ANOVA, and MANCOVA. The results indicate that the teaching of chemical bonding via the animation and jigsaw techniques was more effective than the traditional teaching method in increasing academic achievement. In addition, according to findings from the CbPNMT, the students from the AG were more successful in terms of correct understanding of the particulate nature of matter.

  7. Cooperative Solutions for Sustainable Resource Management.

    PubMed

    Lejano; Davos

    1999-09-01

    / Many environmental management issues can be defined as allocation problems, e.g., the allocation of rights to use common-pool resources or the allocation of the cost of regional resource development projects. The allocation methods developed in the area of cooperative n-person game theory are most appropriate for these problems because they focus on the conditions for engendering and sustaining the necessary cooperation among the involved stakeholders. These solution concepts seek to ensure that the allocation is based on some norm of equity and, most often, also to minimize the incentive for any player to defect from the cooperative venture. We illustrate these solution concepts with an application to a water resource project in Southern California. We argue how the rigorous mathematical nature of these solution concepts should not hinder their application to actual situations and how, with the use of heuristic rules and inexact notions of comparable worths, we can employ these concepts even in approximate fashion. We remind ourselves that the goal of such an endeavor is to convince stakeholders of the equity of a proposed solution and, in so doing, maximize the prospect of sustained cooperation. The alternative to cooperation, on the other hand, may be endless stalemate.KEY WORDS: Core; Game theory; Equity; Common-pool resources; Sustainabilityhttp://link.springer-ny.com/link/service/journals/00267/bibs/24n2p167.html

  8. Cruise summary for P-1-02-SC: acoustic imaging of natural oil and gas seeps and measurement of dissolved methane concentration in coastal waters near Pt. Conception, California

    USGS Publications Warehouse

    Lorenson, T.D.; Dougherty, Jennifer A.; Ussler, William; Paull, Charles K.

    2003-01-01

    Water-column acoustic anomalies and methane concentrations were documented in coastal waters surrounding Pt. Conception, California, in March 2002. The purpose of this survey, supported by the Minerals Management Service, was to locate active oil and gas seeps in the area as a background for further studies to determine hydrocarbon flux, mainly oil, into the environment. Objectives in reaching this goal are to (1) document the locations and geochemically fingerprint natural seeps within the offshore southern Santa Maria Basin; (2) geochemically fingerprint coastal tar residues and potential sources, both onshore and offshore, in this region; (3) establish chemical correlations between offshore active seeps and coastal residues thus linking seep sources to oil residues; (4) measure the rate of natural seepage of individual seeps and attempt to assess regional natural oil and gas seepage rates; (5) attempt to predict transport pathways of oil from seep sources to the coastline and; (6) interpret the petroleum system history for the natural seeps. This survey, addressing objective 1, focused on the area from offshore Surf Beach to the north and Gaviota to the south in water depths ranging from 20 to 500m. In addition, nine stations were sampled outside this area to provide a regional context. Water-column methane concentrations were measured in water samples collected from the R/V Point Sur with Niskin bottles from various depths. A total of 724 water samples from 94 stations were collected.

  9. Concept Mapping

    ERIC Educational Resources Information Center

    Technology & Learning, 2005

    2005-01-01

    Concept maps are graphical ways of working with ideas and presenting information. They reveal patterns and relationships and help students to clarify their thinking, and to process, organize and prioritize. Displaying information visually--in concept maps, word webs, or diagrams--stimulates creativity. Being able to think logically teaches…

  10. Co-production of ethanol, biogas, protein fodder and natural fertilizer in organic farming--evaluation of a concept for a farm-scale biorefinery.

    PubMed

    Oleskowicz-Popiel, Piotr; Kádár, Zsófia; Heiske, Stefan; Klein-Marcuschamer, Daniel; Simmons, Blake A; Blanch, Harvey W; Schmidt, Jens Ejbye

    2012-01-01

    The addition of a biorefinery to an organic farm was investigated, where ethanol was produced from germinated rye grains and whey, and the effluent was separated into two streams: the protein-rich solid fraction, to be used as animal feed, and the liquid fraction, which can be co-digested with clover grass silage to produce biogas. A method for ethanol production from rye was applied by utilizing inherent amylase activity from germination of the seed. Biogas potential of ethanol fermentation effluent was measured through anaerobic digestion trials. The effluent from the trials was assumed to serve as natural fertilizer. A technoeconomic analysis was also performed; total capital investment was estimated to be approximately 4 M USD. Setting a methane selling price according to available incentives for "green electricity" (0.72 USD/m(3)) led to a minimum ethanol selling price of 1.89 USD/L (project lifetime 25 yr, at a discount rate 10%).

  11. Students' Alternative Conceptions and Scientifically Acceptable Conceptions about Gravity.

    ERIC Educational Resources Information Center

    Palmer, David

    2001-01-01

    Identifies students' conceptions that could be categorized as scientifically acceptable and investigates the nature of any possible relationship between these concepts. Investigates 6th and 10th grade students' ideas on whether gravity acted upon a series of moving or non-moving objects in everyday situations. (Contains 41 references.) (Author/YDS)

  12. The Concept of Action Research.

    ERIC Educational Resources Information Center

    Altrichter, Herbert; Kemmis, Stephen; McTaggart, Robin; Zuber-Skerritt, Ortrun

    2002-01-01

    Explains why definition of action research is problematic and presents working definitions developed internationally that indicate its nature, philosophy, and methodology. Suggests that pragmatic approaches to definition serve communication purposes without narrowly confining the concept. (SK)

  13. The concept of a bilayer hydrosphere: From the origins to the methodological approaches

    NASA Astrophysics Data System (ADS)

    Shaporenko, S. I.

    2016-08-01

    This paper considers the results of development of the bilayer hydrosphere concept of the Earth offered by the author in 2000. The bilayering concept is logically based on the classical works in the field of geochemistry and is in the context of mid-twentieth century studies on the structure of the biosphere. The research methods based on this concept are interdisciplinary in nature and make it possible to unify and thereby to facilitate the solution of many problems in the field of oceanology, hydrology and other geographic sciences related to geochemistry.

  14. ULTRACENTRIFUGATION STUDIES ON THE ELEMENTARY BODIES OF VACCINE VIRUS : II. THE INFLUENCE OF SUCROSE, GLYCEROL, AND UREA SOLUTIONS ON THE PHYSICAL NATURE OF VACCINE VIRUS.

    PubMed

    Smadel, J E; Pickels, E G; Shedlovsky, T

    1938-09-30

    ULTRACENTRIFUGAL STUDIES OF THE CL DERMAL STRAIN OF VACCINE VIRUS WARRANT THE FOLLOWING CONCLUSIONS: 1. When suspended in increasing concentrations of sucrose, glycerol, or urea solutions, elementary bodies of vaccinia show variations in sedimentation rate which indicate changes in the density or size of the particles. For a given change in the density of the medium these changes are smallest with sucrose and most marked with urea. The normal rate of sedimentation of Paschen bodies may be restored by resuspending them in dilute buffer solution. 2. The density of elementary bodies of vaccinia suspended in dilute buffer solutions is estimated to be 1.16 gm. per cc. Higher values for the density are found if the particles are suspended in solutions containing sucrose, glycerol, or urea. In 53 per cent sucrose, for example, the density is 1.25 gm. per cc. 3. Paschen bodies appear to be quite permeable to water and urea, less so to glycerol, and only slightly, if at all, to sucrose. 4. The increased density of the elementary bodies of vaccinia in sucrose solutions may be accounted for by an osmotic extraction of water from the particles. On this basis the water which can be thus extracted corresponds to at least a third of the original volume of the particles.

  15. Influence of the nature of the alcohol on the principles of the photocatalytic liberation of hydrogen from aqueous-organic solutions of europium salts

    SciTech Connect

    Myakon'kii, A.G.; Rozenkevich, M.B.; Potapova, G.V.

    1988-09-01

    The process of photocatalytic liberation of hydrogen from aqueous alcohol (ROH - CH/sub 3/OH, C/sub 2/H/sub 5/OH, C/sub 3/H/sub 7/OH, iso-C/sub 3/H/sub 7/OH) solutions of europium salts was investigated. In solutions containing sodium formate as a second organic component, HCOONa and ROH take part in the photoreduction of Eu(III), whereas the main role in the photooxidation of Eu(II) is played by ROH molecules. Such behavior of the system is explained by transfer of an electron in these reactions according to outer- and inner-sphere mechanism, respectively.

  16. Concept Overview.

    ERIC Educational Resources Information Center

    Sandmann, B. J.

    1988-01-01

    Four teaching techniques were used to enhance conceptual learning and to increase student performance in a course in physical-chemical principles at the School of Pharmacy of the University of Missouri-Kansas City. One of the techniques, "concept overview," is described. (MLW)

  17. [Concepts of rational taxonomy].

    PubMed

    Pavlinov, I Ia

    2011-01-01

    The problems are discussed related to development of concepts of rational taxonomy and rational classifications (taxonomic systems) in biology. Rational taxonomy is based on the assumption that the key characteristic of rationality is deductive inference of certain partial judgments about reality under study from other judgments taken as more general and a priory true. Respectively, two forms of rationality are discriminated--ontological and epistemological ones. The former implies inference of classifications properties from general (essential) properties of the reality being investigated. The latter implies inference of the partial rules of judgments about classifications from more general (formal) rules. The following principal concepts of ontologically rational biological taxonomy are considered: "crystallographic" approach, inference of the orderliness of organismal diversity from general laws of Nature, inference of the above orderliness from the orderliness of ontogenetic development programs, based on the concept of natural kind and Cassirer's series theory, based on the systemic concept, based on the idea of periodic systems. Various concepts of ontologically rational taxonomy can be generalized by an idea of the causal taxonomy, according to which any biologically sound classification is founded on a contentwise model of biological diversity that includes explicit indication of general causes responsible for that diversity. It is asserted that each category of general causation and respective background model may serve as a basis for a particular ontologically rational taxonomy as a distinctive research program. Concepts of epistemologically rational taxonomy and classifications (taxonomic systems) can be interpreted in terms of application of certain epistemological criteria of substantiation of scientific status of taxonomy in general and of taxonomic systems in particular. These concepts include: consideration of taxonomy consistency from the

  18. Exact closed-form solutions for the natural frequencies and stability of elastically connected multiple beam system using Timoshenko and high-order shear deformation theory

    NASA Astrophysics Data System (ADS)

    Stojanović, Vladimir; Kozić, Predrag; Janevski, Goran

    2013-02-01

    A general procedure for the determination of the natural frequencies and buckling load for a set of beam system under compressive axial loading is investigated using Timoshenko and high-order shear deformation theory. It is assumed that the set beams of the system are simply supported and continuously joined by a Winkler elastic layer. The model of beam includes the effects of axial loading, shear deformation and rotary inertia. In the special case of identical beams, explicit expressions for the natural frequencies and the critical buckling load are determined using a trigonometric method. The influences of the compressive axial loading and the number of beams in the system on the natural frequencies and the critical buckling load are discussed. These results are of considerable practical interest and have wide application in engineering practice of frameworks.

  19. The effects of the level of inquiry of situated secondary science laboratory activities on students' understanding of concepts and the nature of science, ability to use process skills and attitudes toward problem solving

    NASA Astrophysics Data System (ADS)

    Dana, Lisa Ann

    Although there has been over thirty years of studies on the effects of inquiry-based science instruction on students' understanding of concepts and the nature of science, ability to use process skills, and attitudes toward problem solving and subsequent meta-analyses of these studies, little is conclusive because of the inability of researchers to adequately describe the various levels of inquiry-based science instruction being utilized. In many of these past studies inquiry-based science instruction was vaguely defined. Past descriptions of inquiry have mainly focused on the teacher vs. student responsibility in the parts of a laboratory activity (Herron 1971, Pella, 1961, and Schwab, 1962) and although others have since focused on other various aspects (Luft, 1999; Priestley, Priestley, Sutman, Schumuckler, Hilosky, & White 1998), none have been complete in scope to describe the classroom interactions between teacher and student, before, during and after manipulation of laboratory materials and to clearly define the various levels of inquiry-based science instruction occurring in a classroom. Utilizing some of these previous theoretical frameworks, this study created the Situated Laboratory Activity Instrument (SLAI) that clearly defines various levels of inquiry based upon specific categories of teacher-student behaviors. The term, situated laboratory activities, more clearly represents the time before, during and after the actual manipulation of material. Validity and reliability were established for the SLAI. The instrument was derived from both historical and current instruments for looking at inquiry. The data for the creation and revision of this instrument were collected through initial reliability measures and observing the situated laboratory activities in four secondary physics classrooms during the study. The SLAI was utilized in a preliminary study in a public high school of the effects of various levels of inquiry teaching on students' understanding

  20. Transient rheological behavior of natural polysaccharide xanthan gum solutions in start-up shear flow fields: An experimental study using a strain-controlled rheometer

    NASA Astrophysics Data System (ADS)

    Lee, Ji-Seok; Kim, Yong-Seok; Song, Ki-Won

    2015-08-01

    The objective of the present study is to experimentally investigate the transient rheological behavior of concentrated xanthan gum solutions in start-up shear flow fields. Using a strain-controlled rheometer, a number of constant shear rates were suddenly imposed to aqueous xanthan gum solutions with different concentrations and the resultant shear stress responses were measured with time. The main findings obtained from this study can be summarized as follows: (1) For all shear rates imposed, however low it may be, the shear stress is rapidly increased with time (stress overshoot) upon inception of steady shear flow before passing through the maximum stress value and then gradually decreased with time (stress decay) until reaching a steady state flow. (2) As the imposed shear rate is increased, a more pronounced stress overshoot takes place and the maximum stress value becomes larger, whereas both times at which the maximum stress is observed and needed to reach a steady state flow are shortened. (3) The maximum shear stress is linearly increased with shear rate in a double logarithmic scale and becomes larger with increasing concentration at equal shear rates. In addition, the time at which the maximum stress occurs exhibits a linear relationship with the inverse of shear rate in a double logarithmic scale for all xanthan gum solutions, regardless of their concentrations. (4) The shear stress is sharply increased with an increase in strain until reaching the maximum stress at small range of deformations. The maximum stress is observed at similar strain values, irrespective of the imposed shear rates lower than 10 1/s. (5) The Bird-Leider model can be successfully used with regard to quantitatively predicting the transient behavior of concentrated xanthan gum solutions. However, this model has a fatal weakness in terms of describing a decrease in shear stress (stress decay).

  1. Role of natural organic solutes on the sorption of selenium by coal mine backfill-core samples from the Powder River Basin, Wyoming

    SciTech Connect

    Vance, G.F.; Fadlelmawia, A.A.; Reddy, K.J.

    1995-09-01

    Concentrations of dissolved selenium (Se) as large as 330 {mu}gL{sup -1} have been detected in water samples from backfill aquifers in the southern Powder River Basin (PRB) of northeastern Wyoming. During surface coal mining, rock material overlying the coal is redistributed in relation to its original stratigraphic position; exposure of the previously buried material to surface oxidizing conditions decreases the stability of sulfides and organic matter containing Se, increasing Se concentrations in associated ground waters. Ground-water and backfill-core samples were collected from three sites located at two active mines in the PRB. Dissolved organic carbon (DOC) in the ground-water samples was dominated by the acid fraction (sum of hydrophobic and hydrophilic acids) at 38 to 84% of the DOC; the neutral fraction (sum of hydrophobic and hydrophilic neutrals) ranged from 10 to 55% and the base fraction (sum of hydrophobic and hydrophilic bases) was generally less than 10%. Three sorption experiments were conducted to investigate selenite sorption on backfill-core samples. Selenite concentration in these experiments ranged from 0 to 11 mg kg{sup -1} in backfill-core samples. The first experiment determined the selenite sorption capacity of the backfill-core samples with selenite in distilled-deionized water as a background solution. In the third experiment, hydrophobic and hydrophilic acid fractions, isolated and concentrated from ground-water samples, were added to the selenite background solutions. Results of the three experiments indicated that backfill-core samples have a high sorption capacity for Se (generally, greater than 90% of the added Se) and can sorb as much as 99% of Se added as selenite. A substantial decrease in selenite sorption rates occurred in the presence of individual organic-solute fractions. Hydrophilic acids caused the largest decrease in Se sorption by the backfill-core samples.

  2. Current Concepts in Conception Control

    PubMed Central

    Ringrose, C. A. Douglas

    1963-01-01

    The progressive increase in world population has become a most urgent global problem in recent years. Man has, however, been interested in controlling his reproductivity at the family level for many centuries. Historical aspects of this saga are reviewed. The modern era of conception control was ushered in by Makepeace et al. in 1937 when ovulation inhibition by progesterone was demonstrated. Confirmation of this by Pincus and associates, and development of the potent oral progestational agents, the 19-norsteroids, have made efficient reliable contraception a reality. Experience with one of these agents (Ortho-Novum, 2 mg.) in 115 patients through 805 cycles is presented. Conception control was 100% effective at this dosage. Side effects were minimal. Only three of the women discontinued the tablets because of these effects. All but five in this group of 115 preferred the oral contraceptives to methods previously employed. PMID:13973987

  3. Competition between Reaction and Intramolecular Energy Redistribution in Solution. Observation and Nature of Nonstatistical Dynamics in the Ozonolysis of Vinyl Ethers

    PubMed Central

    Quijano, Larisa Mae M.; Singleton, Daniel A.

    2011-01-01

    Experimental product ratios in ozonolyses of alkyl vinyl ethers in solution do not fit with expectations from statistical rate theories. The selectivity among cleavage pathways increases with the size of the alkyl group but to an extent that is far less than RRKM theory would predict. Trajectory studies account for the observed selectivities and support a mechanism involving a competition between cleavage of the primary ozonide and intramolecular vibrational energy redistribution. An approximate statistical model is presented that assumes that RRKM theory holds for a molecular subset of the primary ozonides, allowing estimates of the rates of energy loss from the primary ozonides based on the observed product ratios. PMID:21812422

  4. Learning to use scientific concepts

    NASA Astrophysics Data System (ADS)

    Wells, Gordon

    2008-07-01

    In responding to the research on conceptual change, this article attempts to make two points. First, scientific concepts are not possessed by individuals; rather, they are part of a culture's resources, which individuals learn to use for their own or for group purposes. Second, particular concepts are most effectively mastered when the learner is deeply engaged in solving a problem for which they function as effective semiotic tools in achieving a solution. On these grounds, it is argued that the mastering of scientific concepts is best achieved through learning to use them in motivated inquiry.

  5. Mild extraction methods using aqueous glucose solution for the analysis of natural dyes in textile artefacts dyed with Dyer's madder (Rubia tinctorum L.).

    PubMed

    Ford, Lauren; Henderson, Robert L; Rayner, Christopher M; Blackburn, Richard S

    2017-03-03

    Madder (Rubia tinctorum L.) has been widely used as a red dye throughout history. Acid-sensitive colorants present in madder, such as glycosides (lucidin primeveroside, ruberythric acid, galiosin) and sensitive aglycons (lucidin), are degraded in the textile back extraction process; in previous literature these sensitive molecules are either absent or present in only low concentrations due to the use of acid in typical textile back extraction processes. Anthraquinone aglycons alizarin and purpurin are usually identified in analysis following harsh back extraction methods, such those using solvent mixtures with concentrated hydrochloric acid at high temperatures. Use of softer extraction techniques potentially allows for dye components present in madder to be extracted without degradation, which can potentially provide more information about the original dye profile, which varies significantly between madder varieties, species and dyeing technique. Herein, a softer extraction method involving aqueous glucose solution was developed and compared to other back extraction techniques on wool dyed with root extract from different varieties of Rubia tinctorum. Efficiencies of the extraction methods were analysed by HPLC coupled with diode array detection. Acidic literature methods were evaluated and they generally caused hydrolysis and degradation of the dye components, with alizarin, lucidin, and purpurin being the main compounds extracted. In contrast, extraction in aqueous glucose solution provides a highly effective method for extraction of madder dyed wool and is shown to efficiently extract lucidin primeveroside and ruberythric acid without causing hydrolysis and also extract aglycons that are present due to hydrolysis during processing of the plant material. Glucose solution is a favourable extraction medium due to its ability to form extensive hydrogen bonding with glycosides present in madder, and displace them from the fibre. This new glucose method offers an

  6. Sorption of hydrophobic organic compounds on natural sorbents and organoclays from aqueous and non-aqueous solutions: a mini-review.

    PubMed

    Moyo, Francis; Tandlich, Roman; Wilhelmi, Brendan S; Balaz, Stefan

    2014-05-09

    Renewed focus on the sorption of hydrophobic organic chemicals (HOCs) onto mineral surfaces and soil components is required due to the increased and wider range of organic pollutants being released into the environment. This mini-review examines the possibility of the contribution and mechanism of HOC sorption onto clay mineral sorbents such as kaolinite, and soil organic matter and the possible role of both in the prevention of environmental contamination by HOCs. Literature data indicates that certain siloxane surfaces can be hydrophobic. Therefore soils can retain HOCs even at low soil organic levels and the extent will depend on the structure of the pollutant and the type and concentration of clay minerals in the sorbent. Clay minerals are wettable by nonpolar solvents and so sorption of HOCs onto them from aqueous and non-aqueous solutions is possible. This is important for two reasons: firstly, the movement and remediation of soil environments will be a function of the concentration and type of clay minerals in the soil. Secondly, low-cost sorbents such as kaolinite and expandable clays can be added to soils or contaminated environments as temporary retention barriers for HOCs. Inorganic cations sorbed onto the kaolinite have a strong influence on the rate and extent of sorption of hydrophobic organic pollutants onto kaolinite. Structural sorbate classes that can be retained by the kaolinite matrix are limited by hydrogen bonding between hydroxyl groups of the octahedral alumosilicate sheet and the tetrahedral sheet with silicon. Soil organic carbon plays a key role in the sorption of HOCs onto soils, but the extent will be strongly affected by the structure of the organic soil matter and the presence of soot. Structural characterisation of soil organic matter in a particular soil should be conducted during a particular contamination event. Contamination by mining extractants and antibiotics will require renewed focus on the use of the QSAR approaches in the

  7. The kinetic and thermodynamic sorption and stabilization of multiwalled carbon nanotubes in natural organic matter surrogate solutions: the effect of surrogate molecular weight.

    PubMed

    Li, Tingting; Lin, Daohui; Li, Lu; Wang, Zhengyu; Wu, Fengchang

    2014-03-01

    Styrene sulfonate (SS) and polystyrene sulfonates (PSSs) were used as surrogates of natural organic matter to study the effect of molecular weight (from 206.2 to 70,000 Da) on their sorption by a multiwalled carbon nanotube (MWCNT) and an activated carbon (AC) and on their stabilization of MWCNT suspension. Results indicate that surface-diffusion through the liquid-sorbent boundary was the rate-controlling step of the kinetic sorption of both MWCNTs and AC, and surface-occupying and pore-filling mechanisms respectively dominated the thermodynamic sorption of MWCNTs and AC. Sorption rates and capacities of MWCNTs and AC in molecular concentration of SS and PSS decreased with increasing molecular weight. The PSSs but not SS facilitated the stabilization of MWCNT suspension because of the increased electrosteric repulsion. The PSSs with more monomers had greater capabilities to stabilize the MWCNT suspension, but the capabilities were comparable after being normalized by the total monomer number.

  8. Sorption of Hydrophobic Organic Compounds on Natural Sorbents and Organoclays from Aqueous and Non-Aqueous Solutions: A Mini-Review

    PubMed Central

    Moyo, Francis; Tandlich, Roman; Wilhelmi, Brendan S.; Balaz, Stefan

    2014-01-01

    Renewed focus on the sorption of hydrophobic organic chemicals (HOCs) onto mineral surfaces and soil components is required due to the increased and wider range of organic pollutants being released into the environment. This mini-review examines the possibility of the contribution and mechanism of HOC sorption onto clay mineral sorbents such as kaolinite, and soil organic matter and the possible role of both in the prevention of environmental contamination by HOCs. Literature data indicates that certain siloxane surfaces can be hydrophobic. Therefore soils can retain HOCs even at low soil organic levels and the extent will depend on the structure of the pollutant and the type and concentration of clay minerals in the sorbent. Clay minerals are wettable by nonpolar solvents and so sorption of HOCs onto them from aqueous and non-aqueous solutions is possible. This is important for two reasons: firstly, the movement and remediation of soil environments will be a function of the concentration and type of clay minerals in the soil. Secondly, low-cost sorbents such as kaolinite and expandable clays can be added to soils or contaminated environments as temporary retention barriers for HOCs. Inorganic cations sorbed onto the kaolinite have a strong influence on the rate and extent of sorption of hydrophobic organic pollutants onto kaolinite. Structural sorbate classes that can be retained by the kaolinite matrix are limited by hydrogen bonding between hydroxyl groups of the octahedral alumosilicate sheet and the tetrahedral sheet with silicon. Soil organic carbon plays a key role in the sorption of HOCs onto soils, but the extent will be strongly affected by the structure of the organic soil matter and the presence of soot. Structural characterisation of soil organic matter in a particular soil should be conducted during a particular contamination event. Contamination by mining extractants and antibiotics will require renewed focus on the use of the QSAR approaches in the

  9. A study on the physicochemical properties of hydroalcoholic solutions to improve the direct exfoliation of natural graphite down to few-layers graphene

    NASA Astrophysics Data System (ADS)

    Fedi, Filippo; Miglietta, Maria Lucia; Polichetti, Tiziana; Ricciardella, Filiberto; Massera, Ettore; Ninno, Domenico; Di Francia, Girolamo

    2015-03-01

    Straightforward methods to produce pristine graphene flakes in large quantities are based on the liquid-phase exfoliation processes. These one-step physical transformations of graphite into graphene offer many unique advantages. To date, a large number of liquids have been employed as exfoliation media exploiting their thermodynamic and chemical features as compared to those of graphene. Here, we pursued the goal of realizing water based mixtures to exfoliate graphite and disperse graphene without the aid of surfactants. To this aim, aqueous mixtures with suitable values of surface tension and Hansen solubility parameters (HSPs), were specifically designed and used. The very high water surface tension was decreased by the addition of solvents with lower surface tensions such as alcohols, obtaining, in this way, more favourable HSP distances. The specific role of each of these thermodynamic features was finally investigated. The results showed that the designed hydroalcoholic solutions were effective in both the graphite exfoliation and dispersion without the addition of any surfactants or other stabilizing agents. Stable graphene suspensions were obtained at concentration comparable to those produced with low-boiling solvents and water/surfactants.

  10. Advanced Gas Storage Concepts: Technologies for the Future

    SciTech Connect

    Freeway, Katy; Rogers, R.E.; DeVries, Kerry L.; Nieland, Joel D.; Ratigan, Joe L.; Mellegard, Kirby D.

    2000-02-01

    This full text product includes: 1) A final technical report titled Advanced Underground Gas Storage Concepts, Refrigerated-Mined Cavern Storage and presentations from two technology transfer workshops held in 1998 in Houston, Texas, and Pittsburgh, Pennsylvania (both on the topic of Chilled Gas Storage in Mined Caverns); 2) A final technical report titled Natural Gas Hydrates Storage Project, Final Report 1 October 1997 - 31 May 1999; 3) A final technical report titled Natural Gas Hydrates Storage Project Phase II: Conceptual Design and Economic Study, Final Report 9 June - 10 October 1999; 4) A final technical report titled Commerical Potential of Natural Gas Storage in Lined Rock Caverns (LRC) and presentations from a DOE-sponsored workshop on Alternative Gas Storage Technologies, held Feb 17, 2000 in Pittsburgh, PA; and 5) Phase I and Phase II topical reports titled Feasibility Study for Lowering the Minimum Gas Pressure in Solution-Mined Caverns Based on Geomechanical Analyses of Creep-Induced Damage and Healing.

  11. Study of Chemical Surface Structure of Natural Sorbents Used for Removing of Pb2+ Ions from Model Aqueous Solutions (part Ii)

    NASA Astrophysics Data System (ADS)

    Bożęcka, Agnieszka; Bożęcki, Piotr; Sanak-Rydlewska, Stanisława

    2014-03-01

    This article presents the results of the chemical structure research of organic sorbent surface such as walnut shells, plums stones and sunflower hulls with using such methods as infrared spectrometry (FTIR) and elemental analysis. Based on the IR spectra identification of functional groups present on the surface of studied materials has been done as well as determination of their effect on the sorption mechanism of Pb2+ ions from aqueous model solutions W artykule przedstawiono wyniki badań chemicznej struktury powierzchni sorbentów organicznych takich jak: łupiny orzecha włoskiego, pestki śliwek oraz łuski słonecznika z wykorzystaniem metody spektrometrii w podczerwieni (FTIR) oraz analizy elementarnej. W oparciu o uzyskane widma IR dokonano identyfikacji grup funkcyjnych obecnych na powierzchni tych materiałów i określono ich wpływ na mechanizm sorpcji jonów Pb2+ z modelowych roztworów wodnych. Analiza elementarna wykazała, że spośród badanych sorbentów, największą zawartość węgla (49,91%) i wodoru (5,93%) mają pestki śliwek. Najwięcej azotu (1,59%) zawierają łuszczyny słonecznika (tabela 1). Zawartość siarki we wszystkich badanych materiałach jest znikoma, dlatego nie udało się jej oznaczyć tą metodą. Obecność pozostałych pierwiastków może świadczyć o istnieniu zarówno alifatycznych jak i aromatycznych połączeń organicznych. Potwierdzeniem tego są również zarejestrowane widma IR (rysunki 1-3). W oparciu o uzyskane wyniki można przypuszczać także, iż udział procesu wymiany jonowej w sorpcji ołowiu z roztworów wodnych jest znaczący. Świadczą o tym m.in. intensywności pasm na widmach IR dla próbek badanych materiałów po ich kontakcie z roztworami jonów Pb2+ (rysunki 4-6).

  12. The Precision Field Lysimeter Concept

    NASA Astrophysics Data System (ADS)

    Fank, J.

    2009-04-01

    respectively. The different soil horizons in the lysimeters are equipped with sensors to measure soil temperature, water content and soil tension. Suction cups are used to get soil water samples. The lower boundary of the lysimeter is designed to maintain equilibrium between the suction applied to the leachate collection system and soil matrix potential thus the suction applied may vary depending on natural conditions - measured using tensiometers - in the field. The lysimeters are built in directly in a test area of 1000 m2 with the same vegetation to prevent island effects on evotranspiration. The topmost part of the lysimeter is realized as a removable ring that mechanical cultivation is possible in the same manner as at the test field. In this presentation the concept and the implementation of the Precision Field Lysimeter is shown. First results on water and solute balances of a 4 years investigation period are discussed.

  13. Technium concept

    NASA Astrophysics Data System (ADS)

    Clement, Marc; Davies, Stephen

    2002-05-01

    Traditionally the economy of Wales has been based on the coal and steel industries. Recently, Wales has elected its own National Assembly and together with the Welsh Development Agency (WDA) and through a Regional Technology Plan, has prioritized the creation and development of a knowledge based economy. The culture of Wales has always placed emphasis on education and for a small nation, has a University sector with an excellent reputation for advanced research. The WDA and the University of Wales Swansea came together to establish Technium, which is an unique concept designed to bridge the gap between advanced University research and commercial exploitation. Technium was co-funded by the WDA and the European Regional Development Fund. The project is seen as the first phase of creating a network of sector specific Techniums across the country, all linked via state of the art telecomm-infrastructure to University centers of research excellence. This paper will describe two case studies, both in the Optics/Photonics field, of research centers being established in Technium by blue chip international companies. Those companies having located in Technium specifically because of the links to high quality university research. One company is Agilent Technologies Inc., USA) a global leader in Optoelectronic components. The second company, ICN Pharmaceuticals Inc, design and develop optical devices to be used in conjunction with pharmaceuticals for the treatment of a range of diseases. Working closely with the WDA and the University of Wales Swansea, these and other companies will pursue product development, sponsor postgraduate research and generate intellectual capital that will benefit the company, students and the region alike.

  14. Water laws and concepts

    USGS Publications Warehouse

    Thomas, H.E.

    1970-01-01

    Throughout human history various laws and customs have developed concerning the individual rights and rights in common to the waters of the earth. Many existing laws and concepts are clearly influenced by the environment in which they originated and reflect the relative abundance or scarcity of water. Many concepts reflect the people's original interests in the water and once established have been passed from generation to generation with little modification. Some laws and concepts have been carried by people in their migrations and colonial expansions to vastly different environments, with rather curious consequences. In many places water laws that had been well adapted to the natural environment have become less tenable because of man's activities in modifying that environment, or because of increasing use of water: Increasing consumptive use shifts the water economy toward lesser abundance or increasing deficiency; increasing nonconsumptive use results in pollution of the water resources, so that they become less suitable for other users. The water-rights systems in the United States vary from State to State: some are reasonably fitted to their environment, some have outlived their place in history, some are wasteful of water, some show favoritism to certain special interests or segments of the population. Water-use rights are universally recognized as real property, with constitutional protection against deprivation without due process of law.

  15. Community concepts.

    PubMed

    Yeung, Thomas; Bates, Tony

    2004-03-01

    Since the publication of "Sustainable Communities--building for the future", Government attention has focused largely on high-density affordable housing in the four "growth areas": Thames Gateway; Ashford; Milton Keynes--South Midlands, and London--Stansted--Cambridge. In this article, Thomas Yeung and Tony Bates suggest that a greater and more sustainable impact would be achieved if architects, planners, and developers considered the potential for community-based water and waste management and on-site energy generation and distribution right from the start of the project. In particular, they consider that the communal nature of hospitals, universities, and public/community housing provides a great opportunity for on-site renewable CHP and/or distributed heating, which could combine global environmental benefits with improved local amenities. They describe a simple model for prioritising energy management in the built environment, and draw on lessons learnt at ETRCL in Dagenham and BedZED in Surrey to offer a few recommendations for Government and developers. Tony Bates is the business development manager for Scott Wilson in the South East and is responsible for the promotion of sustainable communities through relationships with architects, developers, land owners and local authorities. Thomas Yeung leads the Energy Infrastructure Technologies group in Scott Wilson. This team offers an integrated approach to clean community-based energy generation, energy management, waste and water management, sustainable transport, and sustainable buildings/communities.

  16. Calculation of amorphous silica solubilities at 25° to 300°C and apparent cation hydration numbers in aqueous salt solutions using the concept of effective density of water

    USGS Publications Warehouse

    Fournier, Robert O.; Williams, Marshall L.

    1983-01-01

    The solubility of amorphous silica in aqueous salt solutions at 25° to 300°C can be calculated using information on its solubility in pure water and a model in which the activity of water in the salt solution is defined to equal the effective density. pe, of “free” water in that solution. At temperatures of 100°C and above, pe closely equals the product of the density of the solution times the weight fraction of water in the solution. At 25°C, a correction parameter must be applied to pe that incorporates a term called the apparent cation hydration number, h. Because of the many assumptions and other uncertainties involved in determining values of h, by the model used here, the reported numbers are not necessarily real hydration numbers even though they do agree with some published values determined by activity and diffusion methods. Whether or not h is a real hydration number, it would appear to be useful in its inclusion within a more extensive activity coefficient term that describes the departure of silica solubilities in concentrated salt solutions from expected behavior according to the model presented here. Values of h can be calculated from measured amorphous silica solubilities in salt solutions at 25°C provided there is no complexing of dissolved silica with the dissolved salt, or if the degree of complexing is known. The previously postulated aqueous silica-sulfate complexing in aqueous Na2SO4 solutions is supported by results of the present effective density of water model

  17. The role of integrating natural and social science concepts for risk governance and the design of people-centred early warning systems. Case study from the German-Indonesian Tsunami Early Warning System Project (GITEWS)

    NASA Astrophysics Data System (ADS)

    Gebert, Niklas; Post, Joachim

    2010-05-01

    . This requires the integration of natural / spatial and social science concepts, methods and data: E.g. a scenario based approach for tsunami inundation modeling was developed to provide decision makers with options to decide up to what level they aim to protect their people and territory, on the contrary household surveys were conducted for the spatial analysis of the evacuation preparedness of the population as a function of place specific hazard, risk, warning and evacuation perception; remote sensing was applied for the spatial analysis (land-use) of the socio-physical conditions of a city and region for evacuation; and existing social / population statistics were combined with land-use data for the precise spatial mapping of the population exposed to tsunami risks. Only by utilizing such a comprehensive assessment approach valuable information for risk governance can be generated. The results are mapped using GIS and designed according to the specific needs of different end-users, such as public authorities involved in the design of warning dissemination strategies, land-use planners (shelter planning, road network configuration) and NGOs mandated to provide education for the general public on tsunami risk and evacuation behavior. The case study of the city of Padang (one of the pilot areas of GITEWS), Indonesia clearly show, that only by intersecting social (vulnerability) and natural hazards research a comprehensive picture on tsunami risk can be provided with which risk governance in the early warning context can be conducted in a comprehensive, systemic and sustainable manner.

  18. The Theory of Figural Concepts.

    ERIC Educational Resources Information Center

    Fischbein, Efraim

    1993-01-01

    The main thesis of the paper is that geometry deals with mental entities (the so-called geometrical figures) which possess simultaneously conceptual and figural characters. The paper analyzes the internal tensions which may arise in figural concepts because of their double nature, developmental aspects, and didactical implications. (Author/MDH)

  19. Web life: Ask Nature

    NASA Astrophysics Data System (ADS)

    2012-11-01

    Ask Nature is a site devoted to biomimicry, an interdisciplinary field in which practitioners study how animals and plants solve problems, and then use those solutions to develop better human technologies.

  20. Self-assembly concepts for multicompartment nanostructures.

    PubMed

    Gröschel, André H; Müller, Axel H E

    2015-07-28

    Compartmentalization is ubiquitous to many biological and artificial systems, be it for the separate storage of incompatible matter or to isolate transport processes. Advancements in the synthesis of sequential block copolymers offer a variety of tools to replicate natural design principles with tailor-made soft matter for the precise spatial separation of functionalities on multiple length scales. Here, we review recent trends in the self-assembly of amphiphilic block copolymers to multicompartment nanostructures (MCNs) under (semi-)dilute conditions, with special emphasis on ABC triblock terpolymers. The intrinsic immiscibility of connected blocks induces short-range repulsion into discrete nano-domains stabilized by a third, soluble block or molecular additive. Polymer blocks can be synthesized from an arsenal of functional monomers directing self-assembly through packing frustration or response to various fields. The mobility in solution further allows the manipulation of self-assembly processes into specific directions by clever choice of environmental conditions. This review focuses on practical concepts that direct self-assembly into predictable nanostructures, while narrowing particle dispersity with respect to size, shape and internal morphology. The growing understanding of underlying self-assembly mechanisms expands the number of experimental concepts providing the means to target and manipulate progressively complex superstructures.

  1. Self-assembly concepts for multicompartment nanostructures

    NASA Astrophysics Data System (ADS)

    Gröschel, André H.; Müller, Axel H. E.

    2015-07-01

    Compartmentalization is ubiquitous to many biological and artificial systems, be it for the separate storage of incompatible matter or to isolate transport processes. Advancements in the synthesis of sequential block copolymers offer a variety of tools to replicate natural design principles with tailor-made soft matter for the precise spatial separation of functionalities on multiple length scales. Here, we review recent trends in the self-assembly of amphiphilic block copolymers to multicompartment nanostructures (MCNs) under (semi-)dilute conditions, with special emphasis on ABC triblock terpolymers. The intrinsic immiscibility of connected blocks induces short-range repulsion into discrete nano-domains stabilized by a third, soluble block or molecular additive. Polymer blocks can be synthesized from an arsenal of functional monomers directing self-assembly through packing frustration or response to various fields. The mobility in solution further allows the manipulation of self-assembly processes into specific directions by clever choice of environmental conditions. This review focuses on practical concepts that direct self-assembly into predictable nanostructures, while narrowing particle dispersity with respect to size, shape and internal morphology. The growing understanding of underlying self-assembly mechanisms expands the number of experimental concepts providing the means to target and manipulate progressively complex superstructures.

  2. Concept empiricism: a methodological critique.

    PubMed

    Machery, Edouard

    2007-07-01

    Thanks to Barsalou's, Damasio's, Glenberg's, Prinz' and others' work, neo-empiricism is gaining a deserved recognition in the psychology and philosophy of concepts. I argue, however, that neo-empiricists have underestimated the difficulty of providing evidence against the amodal approach to concepts and higher cognition. I highlight three key problems: the difficulty of sorting out amodal predictions from neo-empiricist predictions, the difficulty of finding experimental tasks that are not best solved by imagery and the difficulty of generalizing findings concerning a given cognitive process in a given context to other cognitive processes or other contexts. Finally, solutions to these three problems are considered.

  3. Curious Play: Children's Exploration of Nature

    ERIC Educational Resources Information Center

    Gurholt, Kirsti Pedersen; Sanderud, Jostein Rønning

    2016-01-01

    This article explores the concept of "curious play" as a theoretical framework to understand and communicate children's experiences of free play in nature. The concept emerged interactively from three sources of inspiration: an ethnographically inspired study of children playing in nature; as a critique of the concept of "risky…

  4. On Novice Loop Boundaries and Range Conceptions

    ERIC Educational Resources Information Center

    Ginat, David

    2004-01-01

    The paper presents a study of novice difficulties with range conceptions in loop design. CS2 students were asked to solve four related enumeration tasks, which required various loop boundary specifications. The student solutions varied considerably in conciseness and efficiency. The solution diversity reveals significant differences in range…

  5. Medicinal plants: conception / contraception.

    PubMed

    Chaing, H S; Merino-chavez, G; Yang, L L; Wang, F N; Hafez, E S

    1994-01-01

    Researchers have conducted considerable experiments on the effectiveness and therapeutic values of Chinese herbs and parts of plants. We should not ignore the significance of natural medicine. The Chinese have been perfecting medicinal therapy based on the raw ingredients of plants/herbs and their derivatives for thousands of years. Chinese practitioners of traditional medicine prescribe medicines based on yin and yang. Traditional medicine is communicated in a verb or written form. Natural resources used in traditional medicine to treat diseases are not limited to just medicinal plants but also include animals, shell fish, and minerals. Parts of plants used in traditional medicine are leaves, stems, flowers, bark, and root. Chinese medicine is the world's oldest continuous surviving tradition. The Chinese experimented with local plants, often resulting in mild to violent reactions. This process allowed them to become familiar with poisonous plants and those that could relieve pain or successfully treat illness. Current allopathic medicines are composed of synthetic compounds copied from natural chemical derivatives, which tend to be more potent than the original compound. Some medicinal plants used to effect conception/contraception include Striga astiatica (contraceptive); Eurycoma longifolia (male virility); and a mixture of lengkuas, mengkudu masak, black pepper seeds, ginger, salt, and 2 eggs (increase libido). Women in Malaysia take jamu to preserve their body shape and to provide nutrition during pregnancy. Praneem causes local cell-mediated immunity in the uterus. Clinical trials of Praneem with or without the hCG vaccine are planned.

  6. Concept mapping: a road to critical thinking.

    PubMed

    St Cyr, Sheila K; All, Anita C

    2009-01-01

    Graduate nurses entering the workforce today are, at times, lacking in the area of critical thinking. Giving graduate nurses a concept map would provide a tool to guide their critical thinking until it becomes inherent or second nature. The concept map, a graphic illustration of key points, guides the focus of patient problems using a body system approach. This article details the use of a concept map in the application of knowledge to practice.

  7. Teaching and Learning Economic Creativity: How to Overcome Uncertainty in Realizing Creative New Concepts That Have a Value? How the CRAP System--Coordination & Registration of Action Points--and External Assessment Generates Possible Solutions to Create Value of New Concepts

    ERIC Educational Resources Information Center

    Roelofs, Henk; Nieuwenhuis, Adriaan

    2016-01-01

    How do we identify tools that can overcome uncertainty in realizing value with students using their "idea creativity" in generating and developing ideas in new concepts? Tools that better fit in the mindset of the new generations. The major question of idea creativity, especially in an educational environment is: How to determine and…

  8. Adolescents' Conceptions of Ability and Intelligence.

    ERIC Educational Resources Information Center

    Nicholls, John G.

    Adolescents' developing sense of competence is based on two domains, ability and intelligence. Intelligence testing generally presumes a conception of ability as current capacity that limits the extent to which effort can improve performance. Conceptions of intelligence, and other skills, involve implications about the nature of different forms of…

  9. Student Teachers' Conceptions of Teaching Biology

    ERIC Educational Resources Information Center

    Subramaniam, Karthigeyan

    2014-01-01

    The purpose of this qualitative study was to investigate prospective biology teachers' conceptions of teaching biology and identify how these conceptions revealed their strategies for helping their future students' learning of biology. The study utilized drawings, narratives and interviews to investigate the nature of the prospective biology…

  10. Education for Sustainable Living: A Useful Concept?

    ERIC Educational Resources Information Center

    le Grange, L.

    2002-01-01

    Discusses some emerging discourses on environmental education and how "sustainability" has been used within different discourses. Asserts that the contested nature of the concept does not mean that it cannot be usefully adopted within environmental education processes. Focuses on how the concept has been adopted by students in a…

  11. Number Concepts with "Number Worlds": Thickening Understandings

    ERIC Educational Resources Information Center

    Liljedahl, Peter; Sinclair, Nathalie; Zazkis, Rina

    2006-01-01

    This study focuses on the nature of preservice elementary school teachers' understandings of several concepts in elementary number theory that are evoked by a computer-based microworld called "Number Worlds". In particular, the focus is on the concepts of factor, multiple and prime number. The notion of "thickness" is examined with respect to…

  12. SCIENCE BRIEF: ADVANCED CONCEPTS

    EPA Science Inventory

    Research on advanced concepts will evaluate and demonstrate the application of innovative infrastructure designs, management procedures and operational approaches. Advanced concepts go beyond simple asset management. The infusion of these advanced concepts into established wastew...

  13. Nature and Nationhood: Danish Perspectives

    ERIC Educational Resources Information Center

    Schnack, Karsten

    2009-01-01

    In this paper, I shall discuss Danish perspectives on nature, showing the interdependence of conceptions of "nature" and "nationhood" in the formations of a particular cultural community. Nature, thus construed, is never innocent of culture and cannot therefore simply be "restored" to some pristine, pre-lapsarian…

  14. AXTAR: Mission Design Concept

    NASA Technical Reports Server (NTRS)

    Ray, Paul S.; Chakrabarty, Deepto; Wilson-Hodge, Colleen A.; Philips, Bernard F.; Remillard, Ronald A.; Levine, Alan M.; Wood, Kent S.; Wolff, Michael T.; Gwon, Chul S.; Strohmayer, Tod E.; Briggs, Michael S.; Capizzo, Peter; Fabisinski, Leo; Hopkins, Randall C.; Hornsby, Linda S.; Johnson, Les; Maples, C. Dauphne; Miernik, Janie H.; Thomas, Dan; DeGeronimo, Gianluigi

    2010-01-01

    The Advanced X-ray Timing Array (AXTAR) is a mission concept for X-ray timing of compact objects that combines very large collecting area, broadband spectral coverage, high time resolution, highly flexible scheduling, and an ability to respond promptly to time-critical targets of opportunity. It is optimized for sub-millisecond timing of bright Galactic X-ray sources in order to study phenomena at the natural time scales of neutron star surfaces and black hole event horizons, thus probing the physics of ultra-dense matter, strongly curved spacetimes, and intense magnetic fields. AXTAR s main instrument, the Large Area Timing Array (LATA) is a collimated instrument with 2 50 keV coverage and over 3 square meters effective area. The LATA is made up of an array of super-modules that house 2-mm thick silicon pixel detectors. AXTAR will provide a significant improvement in effective area (a factor of 7 at 4 keV and a factor of 36 at 30 keV) over the RXTE PCA. AXTAR will also carry a sensitive Sky Monitor (SM) that acts as a trigger for pointed observations of X-ray transients in addition to providing high duty cycle monitoring of the X-ray sky. We review the science goals and technical concept for AXTAR and present results from a preliminary mission design study

  15. Multi-pack Disposal Concepts for Spent Fuel (Rev. 0)

    SciTech Connect

    Hadgu, Teklu; Hardin, Ernest; Matteo, Edward N.

    2015-12-01

    At the initiation of the Used Fuel Disposition (UFD) R&D campaign, international geologic disposal programs and past work in the U.S. were surveyed to identify viable disposal concepts for crystalline, clay/shale, and salt host media (Hardin et al., 2012). Concepts for disposal of commercial spent nuclear fuel (SNF) and high-level waste (HLW) from reprocessing are relatively advanced in countries such as Finland, France, and Sweden. The UFD work quickly showed that these international concepts are all “enclosed,” whereby waste packages are emplaced in direct or close contact with natural or engineered materials . Alternative “open” modes (emplacement tunnels are kept open after emplacement for extended ventilation) have been limited to the Yucca Mountain License Application Design (CRWMS M&O, 1999). Thermal analysis showed that, if “enclosed” concepts are constrained by peak package/buffer temperature, waste package capacity is limited to 4 PWR assemblies (or 9-BWR) in all media except salt. This information motivated separate studies: 1) extend the peak temperature tolerance of backfill materials, which is ongoing; and 2) develop small canisters (up to 4-PWR size) that can be grouped in larger multi-pack units for convenience of storage, transportation, and possibly disposal (should the disposal concept permit larger packages). A recent result from the second line of investigation is the Task Order 18 report: Generic Design for Small Standardized Transportation, Aging and Disposal Canister Systems (EnergySolution, 2015). This report identifies disposal concepts for the small canisters (4-PWR size) drawing heavily on previous work, and for the multi-pack (16-PWR or 36-BWR).

  16. A systematic process for adaptive concept exploration

    NASA Astrophysics Data System (ADS)

    Nixon, Janel Nicole

    Complex systems design is currently undergoing a paradigm shift toward Design for Capability. In this new paradigm, fewer vehicles are called on to perform a greater number of missions than ever before. As a result, solutions must be more robust to operational uncertainties while maintaining the ability to perform a greater number of tasks. Due to the nature of this goal, top-level needs are well known while specific vehicle requirements are poorly defined. This presents a combinatorial problem in which there are unlimited potential solutions from which to choose a subset of assets that can meet the stated needs. In order to downselect from the vast number of alternative solutions, designers often rely on qualitative methods because there are simply not enough resources available to thoroughly investigate all the potential solutions. However, qualitative information is often based on preconceived notions about what the design should look like, or partial derivatives. With this kind of static information, there is no reliable way to extrapolate how a particular solution might behave in a different environment or in uncertain operating conditions. For this reason, the ideal is to base concept selection on parametric, quantitative data so that informed, unbiased decisions can be made. However, this kind of information can be expensive and difficult to obtain, which is one reason quantitative analyses are traditionally reserved for optimization or more detailed design after a concept has been selected. This thesis presents a method for streamlining the process of obtaining and interpreting quantitative data for the purpose of creating a low-fidelity modeling and simulation environment. By providing a more efficient means for obtaining such information, quantitative analyses become much more practical for decision-making in the very early stages of design. However, in capability-based design, where the solution space is essentially unrestricted, we are faced with

  17. Natural convection: Fundamentals and applications

    NASA Astrophysics Data System (ADS)

    Kakac, S.; Aung, W.; Viskanta, R.

    Among the topics discussed are: stability solutions for laminar external boundary region flows; natural convection in plane layers and cavities with volumetric energy sources; and turbulence modelling equations. Consideration is also given to: natural convection in enclosures containing tube bundles; natural limiting behaviors in porous media cavity flows; numerical solutions in laminar and turbulent natural convection; and heat transfer in the critical region of binary mixtures. Additional topics discussed include: natural convective cooling of electronic equipment; natural convection suppression in solar collectors; and laser induced buoyancy and forced convection in vertical tubes.

  18. Concepts in Change

    ERIC Educational Resources Information Center

    Rusanen, Anna-Mari; Poyhonen, Samuli

    2013-01-01

    In this article we focus on the concept of concept in conceptual change. We argue that (1) theories of higher learning must often employ two different notions of concept that should not be conflated: psychological and scientific concepts. The usages for these two notions are partly distinct and thus straightforward identification between them is…

  19. Concepts in Communication.

    ERIC Educational Resources Information Center

    Trent, Jimmie D.; And Others

    This book is a collection of ideas and information, gathered from various sources, which should aid college students in formulating their own methods of improving communication. The four main sections of the book are "Concepts of Communication,""Concepts of Source and Message,""Concepts of Communication Criticism," and "Concepts of Interpersonal…

  20. Structural Characteristics of University Engineering Students' Conceptions of Energy.

    ERIC Educational Resources Information Center

    Liu, Xiufeng; Ebenezer, Jazlin; Fraser, Duncan M.

    2002-01-01

    Examines structural characteristics of university engineering students' conceptions of energy elicited through paragraph writing and their relations with categories of their conceptions specific to energy in solution processes identified through interviews. Reports that structures of students' conceptions are characterized primarily by…

  1. Reintroducing the Concept of Complementarity into Psychology.

    PubMed

    Wang, Zheng; Busemeyer, Jerome

    2015-01-01

    Central to quantum theory is the concept of complementarity. In this essay, we argue that complementarity is also central to the emerging field of quantum cognition. We review the concept, its historical roots in psychology, and its development in quantum physics and offer examples of how it can be used to understand human cognition. The concept of complementarity provides a valuable and fresh perspective for organizing human cognitive phenomena and for understanding the nature of measurements in psychology. In turn, psychology can provide valuable new evidence and theoretical ideas to enrich this important scientific concept.

  2. Reintroducing the Concept of Complementarity into Psychology

    PubMed Central

    Wang, Zheng; Busemeyer, Jerome

    2015-01-01

    Central to quantum theory is the concept of complementarity. In this essay, we argue that complementarity is also central to the emerging field of quantum cognition. We review the concept, its historical roots in psychology, and its development in quantum physics and offer examples of how it can be used to understand human cognition. The concept of complementarity provides a valuable and fresh perspective for organizing human cognitive phenomena and for understanding the nature of measurements in psychology. In turn, psychology can provide valuable new evidence and theoretical ideas to enrich this important scientific concept. PMID:26640454

  3. Nature's style: Naturally trendy

    USGS Publications Warehouse

    Cohn, T.A.; Lins, H.F.

    2005-01-01

    Hydroclimatological time series often exhibit trends. While trend magnitude can be determined with little ambiguity, the corresponding statistical significance, sometimes cited to bolster scientific and political argument, is less certain because significance depends critically on the null hypothesis which in turn reflects subjective notions about what one expects to see. We consider statistical trend tests of hydroclimatological data in the presence of long-term persistence (LTP). Monte Carlo experiments employing FARIMA models indicate that trend tests which fail to consider LTP greatly overstate the statistical significance of observed trends when LTP is present. A new test is presented that avoids this problem. From a practical standpoint, however, it may be preferable to acknowledge that the concept of statistical significance is meaningless when discussing poorly understood systems.

  4. Translating concepts of complexity to the field of ergonomics.

    PubMed

    Walker, Guy H; Stanton, Neville A; Salmon, Paul M; Jenkins, Daniel P; Rafferty, Laura

    2010-10-01

    Since 1958 more than 80 journal papers from the mainstream ergonomics literature have used either the words 'complex' or 'complexity' in their titles. Of those, more than 90% have been published in only the past 20 years. This observation communicates something interesting about the way in which contemporary ergonomics problems are being understood. The study of complexity itself derives from non-linear mathematics but many of its core concepts have found analogies in numerous non-mathematical domains. Set against this cross-disciplinary background, the current paper aims to provide a similar initial mapping to the field of ergonomics. In it, the ergonomics problem space, complexity metrics and powerful concepts such as emergence raise complexity to the status of an important contingency factor in achieving a match between ergonomics problems and ergonomics methods. The concept of relative predictive efficiency is used to illustrate how this match could be achieved in practice. What is clear overall is that a major source of, and solution to, complexity are the humans in systems. Understanding complexity on its own terms offers the potential to leverage disproportionate effects from ergonomics interventions and to tighten up the often loose usage of the term in the titles of ergonomics papers. STATEMENT OF RELEVANCE: This paper reviews and discusses concepts from the study of complexity and maps them to ergonomics problems and methods. It concludes that humans are a major source of and solution to complexity in systems and that complexity is a powerful contingency factor, which should be considered to ensure that ergonomics approaches match the true nature of ergonomics problems.

  5. Essentialism, word use, and concepts.

    PubMed

    Braisby, N; Franks, B; Hampton, J

    1996-06-01

    The essentialist approach to word meaning has been used to undermine the fundamental assumptions of the cognitive psychology of concepts. Essentialism assumes that a word refers to a natural kind category in virtue of category members possessing essential properties. In support of this thesis, Kripke and Putnam deploy various intuitions concerning word use under circumstances in which discoveries about natural kinds are made. Although some studies employing counterfactual discoveries and related transformations appear to vindicate essentialism, we argue that the intuitions have not been investigated exhaustively. In particular, we argue that discoveries concerning the essential properties of whole categories (rather than simply of particular category members) are critical to the essentialist intuitions. The studies reported here examine such discovery contexts, and demonstrate that words and concepts are not used in accordance with essentialism. The results are, however, consistent with "representational change" views of concepts, which are broadly Fregean in their motivation. We conclude that since essentialism is not vindicated by ordinary word use, it fails to undermine the cognitive psychology of concepts.

  6. Non-uniform Solute Segregation at Semi-Coherent Metal/Oxide Interfaces

    NASA Astrophysics Data System (ADS)

    Choudhury, Samrat; Aguiar, Jeffery A.; Fluss, Michael J.; Hsiung, Luke L.; Misra, Amit; Uberuaga, Blas P.

    2015-08-01

    The properties and performance of metal/oxide nanocomposites are governed by the structure and chemistry of the metal/oxide interfaces. Here we report an integrated theoretical and experimental study examining the role of interfacial structure, particularly misfit dislocations, on solute segregation at a metal/oxide interface. We find that the local oxygen environment, which varies significantly between the misfit dislocations and the coherent terraces, dictates the segregation tendency of solutes to the interface. Depending on the nature of the solute and local oxygen content, segregation to misfit dislocations can change from attraction to repulsion, revealing the complex interplay between chemistry and structure at metal/oxide interfaces. These findings indicate that the solute chemistry at misfit dislocations is controlled by the dislocation density and oxygen content. Fundamental thermodynamic concepts - the Hume-Rothery rules and the Ellingham diagram - qualitatively predict the segregation behavior of solutes to such interfaces, providing design rules for novel interfacial chemistries.

  7. Non-uniform solute segregation at semi-coherent metal/oxide interfaces

    SciTech Connect

    Choudhury, Samrat; Aguiar, Jeffery A.; Fluss, Michael J.; Hsiung, Luke L.; Misra, Amit; Uberuaga, Blas P.

    2015-08-26

    The properties and performance of metal/oxide nanocomposites are governed by the structure and chemistry of the metal/oxide interfaces. Here we report an integrated theoretical and experimental study examining the role of interfacial structure, particularly misfit dislocations, on solute segregation at a metal/oxide interface. We find that the local oxygen environment, which varies significantly between the misfit dislocations and the coherent terraces, dictates the segregation tendency of solutes to the interface. Depending on the nature of the solute and local oxygen content, segregation to misfit dislocations can change from attraction to repulsion, revealing the complex interplay between chemistry and structure at metal/oxide interfaces. These findings indicate that the solute chemistry at misfit dislocations is controlled by the dislocation density and oxygen content. As a result, fundamental thermodynamic concepts – the Hume-Rothery rules and the Ellingham diagram – qualitatively predict the segregation behavior of solutes to such interfaces, providing design rules for novel interfacial chemistries.

  8. Reinventing Natural Selection

    ERIC Educational Resources Information Center

    Geraedts, Caspar L.; Boersma, Kerst Th.

    2006-01-01

    Although many research studies report students' Lamarckian misconceptions, only a few studies present learning and teaching strategies that focus on the successful development of the concept of natural selection. The learning and teaching strategy for upper secondary students (aged 15-16) presented in this study conducted in The Netherlands is…

  9. Electromarking solution

    DOEpatents

    Bullock, Jonathan S.; Harper, William L.; Peck, Charles G.

    1976-06-22

    This invention is directed to an aqueous halogen-free electromarking solution which possesses the capacity for marking a broad spectrum of metals and alloys selected from different classes. The aqueous solution comprises basically the nitrate salt of an amphoteric metal, a chelating agent, and a corrosion-inhibiting agent.

  10. Finite solutions of fully fuzzy linear system

    NASA Astrophysics Data System (ADS)

    Malkawi, Ghassan; Ahmad, Nazihah; Ibrahim, Haslinda

    2014-12-01

    The solution of Fully Fuzzy Linear System (FFLS) is normally categorized as unique, finite and infinitely many solutions. However, in the case of more than one solution, the finite or alternative solution is not detected when linear programming is considered. Therefore this paper aims to provide a method of using min-max system and absolute system to append new concept for the consistency of FFLS, which is called finite solution of FFLS, where the FFLS have more than two solutions, and not only an infinite solution.

  11. Systems evaluation of thermal bus concepts

    NASA Technical Reports Server (NTRS)

    Stalmach, D. D.

    1982-01-01

    Thermal bus concepts, to provide a centralized thermal utility for large, multihundred kilowatt space platforms, were studied and the results are summarized. Concepts were generated, defined, and screened for inclusion in system level thermal bus trades. Parametric trade studies were conducted in order to define the operational envelope, performance, and physical characteristics of each. Two concepts were selected as offering the most promise for thermal bus development. All of four concepts involved two phase flow in order to meet the required isothermal nature of the thermal bus. Two of the concepts employ a mechanical means to circulate the working fluid, a liquid pump in one case and a vapor compressor in another. Another concept utilizes direct osmosis as the driving force of the thermal bus. The fourth concept was a high capacity monogroove heat pipe. After preliminary sizing and screening, three of these concepts were selected to carry into the trade studies. The monogroove heat pipe concept was deemed unsuitable for further consideration because of its heat transport limitations. One additional concept utilizing capillary forces to drive the working fluid was added. Parametric system level trade studies were performed. Sizing and weight calculations were performed for thermal bus sizes ranging from 5 to 350 kW and operating temperatures in the range of 4 to 120 C. System level considerations such as heat rejection and electrical power penalties and interface temperature losses were included in the weight calculations.

  12. State of ions in electrolyte solutions in the ionic-plasma approximation

    SciTech Connect

    Baldanov, M.M.; Mokhosoev, M.V.

    1986-04-01

    This paper examines the state of ions in the framework of the concept of an ionic plasma. Results are presented of the evaluations of the equivalent conductivity of lithium chloride in aqueous solutions at 18 C. The Debye-Falkenhagne effect and the Wien effect are discussed. The proposed interpretation of the state of ions in electrolyte solutions gives a more natural and more systematic explanation for such factors as the Debye-Falkenhagen dispersion of the electrical conductivity, the Wien effect, and the activity coefficients of electrolytes.

  13. Creative Concept Mapping.

    ERIC Educational Resources Information Center

    Brown, David S.

    2002-01-01

    Recommends the use of concept mapping in science teaching and proposes that it be presented as a creative activity. Includes a sample lesson plan of a potato stamp concept mapping activity for astronomy. (DDR)

  14. MCCB warm adjustment testing concept

    NASA Astrophysics Data System (ADS)

    Erdei, Z.; Horgos, M.; Grib, A.; Preradović, D. M.; Rodic, V.

    2016-08-01

    This paper presents an experimental investigation in to operating of thermal protection device behavior from an MCCB (Molded Case Circuit Breaker). One of the main functions of the circuit breaker is to assure protection for the circuits where mounted in for possible overloads of the circuit. The tripping mechanism for the overload protection is based on a bimetal movement during a specific time frame. This movement needs to be controlled and as a solution to control this movement we choose the warm adjustment concept. This concept is meant to improve process capability control and final output. The warm adjustment device design will create a unique adjustment of the bimetal position for each individual breaker, determined when the testing current will flow thru a phase which needs to trip in a certain amount of time. This time is predetermined due to scientific calculation for all standard types of amperages and complies with the IEC 60497 standard requirements.

  15. Subnational variations in conceptions.

    PubMed

    Wood, R

    1996-01-01

    Conception statistics are derived from information collected at the registration of live births, still births, and legal abortions. This article looks at how conception rates vary across England and Wales using the 1991 ONS area classification of DHAs (Population Trends 79). A comparison is made between age-specific conception rates for different area classification groups in 1993, and changes between 1983 and 1993 are examined. Correlations between certain social and economic factors and conception rates are also analysed.

  16. Conceptions of Ability.

    ERIC Educational Resources Information Center

    Jagacinski, Carolyn M.; Nicholls, John G.

    Two different conceptions of ability are proposed. The first conception of ability is more differentiated and generally employed by adults and older children. Here ability level is defined with reference to the performance of others assuming that optimum effort was employed. High ability means higher than others. The second conception of ability…

  17. Threshold Concepts in Biochemistry

    ERIC Educational Resources Information Center

    Loertscher, Jennifer

    2011-01-01

    Threshold concepts can be identified for any discipline and provide a framework for linking student learning to curricular design. Threshold concepts represent a transformed understanding of a discipline, without which the learner cannot progress and are therefore pivotal in learning in a discipline. Although threshold concepts have been…

  18. Concept Image Revisited

    ERIC Educational Resources Information Center

    Bingolbali, Erhan; Monaghan, John

    2008-01-01

    Concept image and concept definition is an important construct in mathematics education. Its use, however, has been limited to cognitive studies. This article revisits concept image in the context of research on undergraduate students' understanding of the derivative which regards the context of learning as paramount. The literature, mainly on…

  19. The Meritocratic Conception of Educational Equality: Ideal Theory Run Amuck

    ERIC Educational Resources Information Center

    Howe, Kenneth R.

    2015-01-01

    The dominant conception of educational equality in the United States is meritocratic: an individual's chances of educational achievements should track only (natural) talent and effort, not social class or other morally irrelevant factors. The meritocratic conception must presuppose that natural talent and effort can be isolated from social…

  20. Reconceptualizing the "Nature" of Childhood

    ERIC Educational Resources Information Center

    Taylor, Affrica

    2011-01-01

    This interdisciplinary article draws upon human geography to bring fresh new perspectives to the relationship between two commonly conflated concepts: "childhood" and "nature". Childhood studies scholars have gone a long way towards retheorizing childhood beyond the "natural" and the "universal" by pointing to its historical and cultural…

  1. Associative concept learning in animals.

    PubMed

    Zentall, Thomas R; Wasserman, Edward A; Urcuioli, Peter J

    2014-01-01

    Nonhuman animals show evidence for three types of concept learning: perceptual or similarity-based in which objects/stimuli are categorized based on physical similarity; relational in which one object/stimulus is categorized relative to another (e.g., same/different); and associative in which arbitrary stimuli become interchangeable with one another by virtue of a common association with another stimulus, outcome, or response. In this article, we focus on various methods for establishing associative concepts in nonhuman animals and evaluate data documenting the development of associative classes of stimuli. We also examine the nature of the common within-class representation of samples that have been associated with the same reinforced comparison response (i.e., many-to-one matching) by describing manipulations for distinguishing possible representations. Associative concepts provide one foundation for human language such that spoken and written words and the objects they represent become members of a class of interchangeable stimuli. The mechanisms of associative concept learning and the behavioral flexibility it allows, however, are also evident in the adaptive behaviors of animals lacking language.

  2. ASSOCIATIVE CONCEPT LEARNING IN ANIMALS

    PubMed Central

    Zentall, Thomas R.; Wasserman, Edward A.; Urcuioli, Peter J.

    2014-01-01

    Nonhuman animals show evidence for three types of concept learning: perceptual or similarity-based in which objects/stimuli are categorized based on physical similarity; relational in which one object/stimulus is categorized relative to another (e.g., same/different); and associative in which arbitrary stimuli become interchangeable with one another by virtue of a common association with another stimulus, outcome, or response. In this article, we focus on various methods for establishing associative concepts in nonhuman animals and evaluate data documenting the development of associative classes of stimuli. We also examine the nature of the common within-class representation of samples that have been associated with the same reinforced comparison response (i.e., many-to-one matching) by describing manipulations for distinguishing possible representations. Associative concepts provide one foundation for human language such that spoken and written words and the objects they represent become members of a class of interchangeable stimuli. The mechanisms of associative concept learning and the behavioral flexibility it allows, however, are also evident in the adaptive behaviors of animals lacking language. PMID:24170540

  3. Hydrophobic Solvation: Aqueous Methane Solutions

    ERIC Educational Resources Information Center

    Konrod, Oliver; Lankau, Timm

    2007-01-01

    A basic introduction to concept of a solvation shell around an apolar solute as well as its detection is presented. The hydrophobic solvation of toluene is found to be a good teaching example which connects macroscopic, phenomenological thermodynamic results with an atomistic point of view.

  4. Solid Solutions

    NASA Astrophysics Data System (ADS)

    Lee, Go-Eun; Kim, Il-Ho; Lim, Young Soo; Seo, Won-Seon; Choi, Byeong-Jun; Hwang, Chang-Won

    2014-06-01

    Since Bi2Te3 and Bi2Se3 have the same crystal structure, they form a homogeneous solid solution. Therefore, the thermal conductivity of the solid solution can be reduced by phonon scattering. The thermoelectric figure of merit can be improved by controlling the carrier concentration through doping. In this study, Bi2Te2.85Se0.15:D m (D: dopants such as I, Cu, Ag, Ni, Zn) solid solutions were prepared by encapsulated melting and hot pressing. All specimens exhibited n-type conduction in the measured temperature range (323 K to 523 K), and their electrical conductivities decreased slightly with increasing temperature. The undoped solid solution showed a carrier concentration of 7.37 × 1019 cm-3, power factor of 2.1 mW m-1 K-1, and figure of merit of 0.56 at 323 K. The figure of merit ( ZT) was improved due to the increased power factor by I, Cu, and Ag dopings, and maximum ZT values were obtained as 0.76 at 323 K for Bi2Te2.85Se0.15:Cu0.01 and 0.90 at 423 K for Bi2Te2.85Se0.15:I0.005. However, the thermoelectric properties of Ni- and Zn-doped solid solutions were not enhanced.

  5. Concepts for Intuitive and Abbreviated Planning Procedures

    DTIC Science & Technology

    2005-12-01

    developing a military planning process that is easier to perform, more effective, and more consistent with natural human reasoning capabilities than...eleven specific concepts that should be considered in development of an abbreviated, intuitive planning process . This report also presents a...prototype process to serve as a framework in which to consider how intuitive planning concepts might be synthesized with existing planning procedures

  6. Précis of doing without concepts.

    PubMed

    Machery, Edouard

    2010-06-01

    Although cognitive scientists have learned a lot about concepts, their findings have yet to be organized in a coherent theoretical framework. In addition, after twenty years of controversy, there is little sign that philosophers and psychologists are converging toward an agreement about the very nature of concepts. Doing without Concepts (Machery 2009) attempts to remedy this state of affairs. In this article, I review the main points and arguments developed at greater length in Doing without Concepts.

  7. Perspectives on culture and concepts.

    PubMed

    ojalehto, Bethany l; Medin, Douglas L

    2015-01-03

    The well-respected tradition of research on concepts uses cross-cultural comparisons to explore which aspects of conceptual behavior are universal versus culturally variable. This work continues, but it is being supplemented by intensified efforts to study how conceptual systems and cultural systems interact to modify and support each other. For example, cultural studies within the framework of domain specificity (e.g., folkphysics, folkpsychology, folkbiology) are beginning to query the domains themselves and offer alternative organizing principles (e.g., folksociology, folkecology). Findings highlight the multifaceted nature of both concepts and culture: Individuals adopt distinct conceptual construals in accordance with culturally infused systems such as language and discourse, knowledge and beliefs, and epistemological orientations. This picture complicates questions about cognitive universality or variability, suggesting that researchers may productively adopt a systems-level approach to conceptual organization and cultural epistemologies. Related implications for diversity in cognitive science are discussed.

  8. Mimicking natural bio-mineralization processes: a new tool for osteochondral scaffold development.

    PubMed

    Tampieri, Anna; Sprio, Simone; Sandri, Monica; Valentini, Federica

    2011-10-01

    In recent years, the concept of regenerative medicine has gained great importance, particularly in the field of orthopaedics, in which current solutions are based mainly on the replacement of damaged tissues with devices that function only as structural replacements with limited regenerative capacity. New regenerative solutions can be obtained by taking inspiration from nature, which surrounds us with a multitude of organisms endowed with extraordinary performance. In particular, bio-mineralization, which is the basis of the formation of load-bearing structures in vertebrate and invertebrate organisms, can be exploited to achieve innovative devices for the repair and reconstruction of bone and osteo-cartilaginous tissues.

  9. Specialization: A Detriment to Problem Conception

    ERIC Educational Resources Information Center

    Siller, Thomas J.; Johnson, Gearold R.

    2010-01-01

    Specialization is an agent of separation, both between competing specialists and between technology and society. Specialization is not an agent of integration. In the problem conception phase of the engineering design process, the emphasis must be on formulating and developing the questions that will frame the ultimate design solution. Using…

  10. Mentoring concepts applied to clinical practice.

    PubMed

    Parker, D

    1992-08-01

    An alternative to traditional forms of orientation using mentoring or related concepts is one possible solution to motivate and inspire nurses during a time when this profession is faced with nursing shortages and burnout. This article will address the advantages and disadvantages to mentoring based on a literature review and personal experience.

  11. Promoting Conceptual Understanding via Adaptive Concept Maps

    ERIC Educational Resources Information Center

    Moore, Jacob P.

    2013-01-01

    The purpose of this study is to explore the feasibility and effectiveness of a scalable concept map based navigation system for a digital textbook. A literature review has been conducted to identify possible methods to promote conceptual understanding in the context of a digital textbook, and these hypothesized solutions will be evaluated through…

  12. Influence of the ionic strength and solid/solution ratio on Ca(II)-for-Na+ exchange on montmorillonite. Part 2: Understanding the effect of the m/V ratio. Implications for pore water composition and element transport in natural media.

    PubMed

    Tertre, E; Ferrage, E; Bihannic, I; Michot, L J; Prêt, D

    2011-11-01

    The aim of the present paper is to clarify previous results showing that selectivity coefficients determined for the exchange of Na(+) for Ca(2+) in montmorillonite were dependent on the solid/solution ratio. The organization of montmorillonite suspensions upon Na(+)/Ca(II) exchange was analyzed by combining optical microscopy, small-angle X-ray scattering and X-ray diffraction. All samples displayed flocculated characteristics, eliminating the possibility of contrasting accessibility of sorption sites with the solid/solution ratio. Modeling of experimental X-ray diffraction patterns was used to quantify the relative proportions of interlayer Ca(2+) and Na(+) cations along the exchange isotherm. The results further confirmed the influence of the solid/solution ratio on the degree of interlayer Ca(II)-for-Na(+) exchange, and specific selectivity coefficients for interlayer sites were determined. The effect of the solid/solution ratio was finally interpreted by the resulting local changes in the solution chemistry. We demonstrated that by accounting for the Donnan effect, the different data can be interpreted using a single selectivity coefficient. The obtained Kc constant was successfully applied to interpret existing hydrogeochemical data on a natural aquitard. This most likely represents a more constrained and valid approach for the modeling of reactive element transport in natural media than does the poorly defined Kd parameter.

  13. -Saturated Solutions

    NASA Astrophysics Data System (ADS)

    Eliyan, Faysal Fayez; Alfantazi, Akram

    2014-11-01

    This paper presents an electrochemical study on the corrosion behavior of API-X100 steel, heat-treated to have microstructures similar to those of the heat-affected zones (HAZs) of pipeline welding, in bicarbonate-CO2 saturated solutions. The corrosion reactions, onto the surface and through the passive films, are simulated by cyclic voltammetry. The interrelation between bicarbonate concentration and CO2 hydration is analyzed during the filming process at the open-circuit potentials. In dilute bicarbonate solutions, H2CO3 drives more dominantly the cathodic reduction and the passive films form slowly. In the concentrated solutions, bicarbonate catalyzes both the anodic and cathodic reactions, only initially, after which it drives a fast-forming thick passivation that inhibits the underlying dissolution and impedes the cathodic reduction. The significance of the substrate is as critical as that of passivation in controlling the course of the corrosion reactions in the dilute solutions. For fast-cooled (heat treatment) HAZs, its metallurgical significance becomes more comparable to that of slower-cooled HAZs as the bicarbonate concentration is higher.

  14. Sound Solutions

    ERIC Educational Resources Information Center

    Starkman, Neal

    2007-01-01

    Poor classroom acoustics are impairing students' hearing and their ability to learn. However, technology has come up with a solution: tools that focus voices in a way that minimizes intrusive ambient noise and gets to the intended receiver--not merely amplifying the sound, but also clarifying and directing it. One provider of classroom audio…

  15. Polymer solutions

    DOEpatents

    Krawczyk, Gerhard Erich; Miller, Kevin Michael

    2011-07-26

    There is provided a method of making a polymer solution comprising polymerizing one or more monomer in a solvent, wherein said monomer comprises one or more ethylenically unsaturated monomer that is a multi-functional Michael donor, and wherein said solvent comprises 40% or more by weight, based on the weight of said solvent, one or more multi-functional Michael donor.

  16. A system model to integrate the “Green Manufacturing” concept in Romanian manufacturing organisation

    NASA Astrophysics Data System (ADS)

    Tilină, D. I.; Zapciu, M.; Mohora, C.

    2015-11-01

    In Romania, the large majorities of the manufacturing companies consume natural resources and energy in an unsustainable manner. Over the years, the emissions of greenhouse gases have led not only to many environmental problems but also to important social and economic problems. A real solution to help the Romanian manufacturing companies to adapt to the new legislative requirements is the green manufacturing implementation. Considering the current situation, the purpose of this paper is to present a model that will integrate the green manufacturing concept at the organizational level based on the practices identified in the Romanian manufacturing companies at the operational level in the context of sustainable development.

  17. Linking social, ecological, and physical science to advance natural and nature-based protection for coastal communities.

    PubMed

    Arkema, Katie K; Griffin, Robert; Maldonado, Sergio; Silver, Jessica; Suckale, Jenny; Guerry, Anne D

    2017-03-30

    Interest in the role that ecosystems play in reducing the impacts of coastal hazards has grown dramatically. Yet the magnitude and nature of their effects are highly context dependent, making it difficult to know under what conditions coastal habitats, such as saltmarshes, reefs, and forests, are likely to be effective for saving lives and protecting property. We operationalize the concept of natural and nature-based solutions for coastal protection by adopting an ecosystem services framework that propagates the outcome of a management action through ecosystems to societal benefits. We review the literature on the basis of the steps in this framework, considering not only the supply of coastal protection provided by ecosystems but also the demand for protective services from beneficiaries. We recommend further attention to (1) biophysical processes beyond wave attenuation, (2) the combined effects of multiple habitat types (e.g., reefs, vegetation), (3) marginal values and expected damage functions, and, in particular, (4) community dependence on ecosystems for coastal protection and co-benefits. We apply our approach to two case studies to illustrate how estimates of multiple benefits and losses can inform restoration and development decisions. Finally, we discuss frontiers for linking social, ecological, and physical science to advance natural and nature-based solutions to coastal protection.

  18. Lesson "Balance in Nature

    NASA Astrophysics Data System (ADS)

    Chapanova, V.

    2012-04-01

    Lesson "Balance in Nature" This simulation game-lesson (Balance in Nature) gives an opportunity for the students to show creativity, work independently, and to create models and ideas. It creates future-oriented thought connected to their experience, allowing them to propose solutions for global problems and personal responsibility for their activities. The class is divided in two teams. Each team chooses questions. 1. Question: Pollution in the environment. 2. Question: Care for nature and climate. The teams work on the chosen tasks. They make drafts, notes and formulate their solutions on small pieces of paper, explaining the impact on nature and society. They express their points of view using many different opinions. This generates alternative thoughts and results in creative solutions. With the new knowledge and positive behaviour defined, everybody realizes that they can do something positive towards nature and climate problems and the importance of individuals for solving global problems is evident. Our main goal is to recover the ecological balance, and everybody explains his or her own well-grounded opinions. In this work process the students obtain knowledge, skills and more responsible behaviour. This process, based on his or her own experience, dialogue and teamwork, helps the participant's self-development. Making the model "human↔ nature" expresses how human activities impact the natural Earth and how these impacts in turn affect society. Taking personal responsibility, we can reduce global warming and help the Earth. By helping nature we help ourselves. Teacher: Veselina Boycheva-Chapanova " Saint Patriarch Evtimii" Scholl Str. "Ivan Vazov"-19 Plovdiv Bulgaria

  19. Resilience - A Concept

    DTIC Science & Technology

    2016-04-05

    Image designed by Diane Fleischer Resilience—A CONCEPT Col Dennis J. Rensel, USAF (Ret.) Resilience takes on many definitions and ideas depending...2015, Vol. 22 No. 3 : 294–324 A Publication of the Defense Acquisition University http://www.dau.mil Resilience as a term has as many definitions as...people who talk about it. What if resiliency is treated as a concept? How do you measure a concept? In reviewing many definitions , “each [ definition

  20. Machine learning-based coreference resolution of concepts in clinical documents

    PubMed Central

    Ware, Henry; Mullett, Charles J; El-Rawas, Oussama

    2012-01-01

    Objective Coreference resolution of concepts, although a very active area in the natural language processing community, has not yet been widely applied to clinical documents. Accordingly, the 2011 i2b2 competition focusing on this area is a timely and useful challenge. The objective of this research was to collate coreferent chains of concepts from a corpus of clinical documents. These concepts are in the categories of person, problems, treatments, and tests. Design A machine learning approach based on graphical models was employed to cluster coreferent concepts. Features selected were divided into domain independent and domain specific sets. Training was done with the i2b2 provided training set of 489 documents with 6949 chains. Testing was done on 322 documents. Results The learning engine, using the un-weighted average of three different measurement schemes, resulted in an F measure of 0.8423 where no domain specific features were included and 0.8483 where the feature set included both domain independent and domain specific features. Conclusion Our machine learning approach is a promising solution for recognizing coreferent concepts, which in turn is useful for practical applications such as the assembly of problem and medication lists from clinical documents. PMID:22582205

  1. Evolving Ethical Concepts

    ERIC Educational Resources Information Center

    Potter, Van Rensselaer

    1977-01-01

    Discusses the role of the scientist in changing ethical concepts from simple interpersonal and theological imperatives towards "survival imperatives that must form the core of environmental bioethics." (CS)

  2. Natural Xanthones

    NASA Astrophysics Data System (ADS)

    Denisova-Dyatlova, O. A.; Glyzin, V. I.

    1982-10-01

    The available information on the abundance of natural xanthones in nature and the methods for the determination of their structure, biogenesis, and pharmacological properties is surveyed and described systematically. The bibliography includes 151 references.

  3. The Nature of Natural Hazards Communication (Invited)

    NASA Astrophysics Data System (ADS)

    Kontar, Y. Y.

    2013-12-01

    Some of the many issues of interest to natural hazards professionals include the analysis of proactive approaches to the governance of risk from natural hazards and approaches to broaden the scope of public policies related to the management of risks from natural hazards, as well as including emergency and environmental management, community development and spatial planning related to natural hazards. During the talk we will present results of scientific review, analysis and synthesis, which emphasize same new trends in communication of the natural hazards theories and practices within an up-to-the-minute context of new environmental and climate change issues, new technologies, and a new focus on resiliency. The presentation is divided into five sections that focus on natural hazards communication in terms of education, risk management, public discourse, engaging the public, theoretical perspectives, and new media. It includes results of case studies and best practices. It delves into natural hazards communication theories, including diffusion, argumentation, and constructivism, to name a few. The presentation will provide information about: (1) A manual of natural hazards communication for scientists, policymakers, and media; (2) An up-to-the-minute context of environmental hazards, new technologies & political landscape; (3) A work by natural hazards scientists for geoscientists working with social scientists and communication principles; (4) A work underpinned by key natural hazards communication theories and interspersed with pragmatic solutions; (5) A work that crosses traditional natural hazards boundaries: international, interdisciplinary, theoretical/applied. We will further explore how spatial planning can contribute to risk governance by influencing the occupation of natural hazard-prone areas, and review the central role of emergency management in risk policy. The goal of this presentation is to contribute to the augmentation of the conceptual framework

  4. Hamiltonian inclusive fitness: a fitter fitness concept

    PubMed Central

    Costa, James T.

    2013-01-01

    In 1963–1964 W. D. Hamilton introduced the concept of inclusive fitness, the only significant elaboration of Darwinian fitness since the nineteenth century. I discuss the origin of the modern fitness concept, providing context for Hamilton's discovery of inclusive fitness in relation to the puzzle of altruism. While fitness conceptually originates with Darwin, the term itself stems from Spencer and crystallized quantitatively in the early twentieth century. Hamiltonian inclusive fitness, with Price's reformulation, provided the solution to Darwin's ‘special difficulty’—the evolution of caste polymorphism and sterility in social insects. Hamilton further explored the roles of inclusive fitness and reciprocation to tackle Darwin's other difficulty, the evolution of human altruism. The heuristically powerful inclusive fitness concept ramified over the past 50 years: the number and diversity of ‘offspring ideas’ that it has engendered render it a fitter fitness concept, one that Darwin would have appreciated. PMID:24132089

  5. "Disease entity" as the key theoretical concept of medicine.

    PubMed

    Hucklenbroich, Peter

    2014-12-01

    Philosophical debates about the concept of disease, particularly of mental disease, might benefit from reconsideration and a closer look at the established terminology and conceptual structure of contemporary medical pathology and clinical nosology. The concepts and principles of medicine differ, to a considerable extent, from the ideas and notions of philosophical theories of disease. In medical theory, the concepts of disease entity and pathologicity are, besides the concept of disease itself, of fundamental importance, and they are essentially connected to the concepts cause of disease or etiological factor, natural course or natural history of disease, and pathological disposition. It is the concept of disease entity that is of key importance for understanding medical pathology and theory of disease. Its central role is shown by a short reconstruction of its main features and its intrinsic connection to the concept of pathologicity. The meaning of pathologicity is elucidated by explicating the underlying criteria.

  6. Solving Solutions: Exploring Unknowns through Chemistry.

    ERIC Educational Resources Information Center

    Burns, John; Yoshina, Granville; Goodding, Debbie; Streitberger, Eric

    2000-01-01

    Presents a chemistry activity that introduces students to one type of chemical bond by developing the integer operation concept of zero pairs. Leads to an activity of combining drops of 0.3 molar solutions to form six different colored precipitates from five solutions. (ASK)

  7. Illustrating Chemical Concepts through Food Systems: Introductory Chemistry Experiments.

    ERIC Educational Resources Information Center

    Chambers, E., IV; Setser, C. S.

    1980-01-01

    Demonstrations involving foods that illustrate chemical concepts are described, including vaporization of liquids and Graham's law of diffusion, chemical reaction rates, adsorption, properties of solutions, colloidal dispersions, suspensions, and hydrogen ion concentration. (CS)

  8. A Concept Study for the Mars Atmosphere Experiment for Ceramic Oxygen Generation (MAXCOG)

    NASA Astrophysics Data System (ADS)

    Christian, J. A.; Sabolsky, E.; Rohschneider, R.; Gerdes, K.; Mebane, D.; Zondlo, J. W.; Liu, X.; Unruh, B.; Hanel, J.; Kleinhenz, J.

    2014-07-01

    MAXCOG is an ISRU precursor concept that matures enabling technologies for future exploration missions to Mars. This concept uses a Solid-Oxide Electrolysis Cell (SOEC)-based solution to produce propellant-grade oxygen from the martian atmosphere.

  9. Special solutions to Chazy equation

    NASA Astrophysics Data System (ADS)

    Varin, V. P.

    2017-02-01

    We consider the classical Chazy equation, which is known to be integrable in hypergeometric functions. But this solution has remained purely existential and was never used numerically. We give explicit formulas for hypergeometric solutions in terms of initial data. A special solution was found in the upper half plane H with the same tessellation of H as that of the modular group. This allowed us to derive some new identities for the Eisenstein series. We constructed a special solution in the unit disk and gave an explicit description of singularities on its natural boundary. A global solution to Chazy equation in elliptic and theta functions was found that allows parametrization of an arbitrary solution to Chazy equation. The results have applications to analytic number theory.

  10. The Self Concept.

    ERIC Educational Resources Information Center

    Fitzgibbon, Ann

    The purpose of this paper is to increase awareness of the self concept as a variable, to indicate what is known about the self concept from existing research, to discuss its importance to the school and its effect on learning, and to offer a method of assessment which is tied to a definition arbitrarily made as a starting point for researchers. A…

  11. Avionics technology - system concepts

    NASA Technical Reports Server (NTRS)

    Bull, J. S.; Huntoon, R. B.

    1984-01-01

    Avionics System Concepts to meet technology needs of advanced helicopter integrated cockpit design are identified. Specific avionics system concepts which should be conducted and/or support by NASA to most effectively aid industry in advanced helicopter integrated cockpit design are also identified. Candidate Missions and Mission Requirements to meet technology needs are considered.

  12. Values Concepts and Techniques.

    ERIC Educational Resources Information Center

    National Education Association, Washington, DC.

    This book contains 29 articles for elementary and secondary teachers dealing with fundamental concepts and teaching techniques in values education. Part one of the book deals with concepts. Louis E. Raths examines valuing and its relationship to freedom and intelligence. The cognitive developmental approach to moral education is discussed by…

  13. New Concepts of Work.

    ERIC Educational Resources Information Center

    Canadian Council on Social Development, Ottawa (Ontario).

    The two-day Canadian conference focused on the topics: "Why are new concepts of work emerging?" and "How can we encourage desirable new work concepts in our society?" Following an introductory summary by David P. Ross, Stephen Peitchinis (Dean, School of Business Administration, University of Calgary) presented the economic…

  14. Learning Our Concepts

    ERIC Educational Resources Information Center

    Laverty, Megan J.

    2009-01-01

    Richard Stanley Peters appreciates the centrality of concepts for everyday life, however, he fails to recognize their pedagogical dimension. He distinguishes concepts employed at the first-order (our ordinary language-use) from second-order conceptual clarification (conducted exclusively by academically trained philosophers). This distinction…

  15. Integral Fast Reactor concept

    SciTech Connect

    Till, C.E.; Chang, Y.I.

    1986-01-01

    The Integral Fast Reactor (IFR) is an innovative LMR concept, being developed at Argonne National Laboratory, that fully exploits the inherent properties of liquid metal cooling and metallic fuel to achieve breakthroughs in economics and inherent safety. This paper describes key features and potential advantages of the IFR concept, technology development status, fuel cycle economics potential, and future development path.

  16. Data Transmission Concepts.

    ERIC Educational Resources Information Center

    Christenson, Chris

    1995-01-01

    Introduces some basic concepts related to the transmission of data from a computer to its peripherals to help distance educators make decisions regarding computer equipment purchases for their institutions. The following data transmission concepts are described: cables, serial and parallel, synchronous and asynchronous, bandwidth, and analog and…

  17. Thinking to Learn Concepts.

    ERIC Educational Resources Information Center

    Parker, Walter C.

    1988-01-01

    States that programs which link the teaching of thinking with content have the greatest instructional value. Presents a concept formation lesson, based on the works of Taba (1967) and Ehrenberg (1978), which requires students to learn a concept by studying several examples and noting their similarities and differences. Includes a sample…

  18. Teach Concepts, Not Words.

    ERIC Educational Resources Information Center

    Williamson, Leon E.

    Since concepts are the mental divisions man makes among the concrete and abstract phenomena of his environment so he may generate, maneuver, and control their relationships in a manner ot satisfy his physical, emotional, social, and aesthetic needs, concepts should be the vortex of intelligence. Too often students are taught as if they lack a…

  19. [Electronic documentation in medicine; flexible concepts versus isolated solutions].

    PubMed

    Ganslandt, T; Krieglstein, C F; Müller, M L; Senninger, N; Prokosch, H U

    2000-01-01

    Computer-based medical documentation so far proved advantageous especially through standardization of data entry and increased access speed. Additional benefits can be achieved through the implementation of integrated, cross-project documentation tools and their integration into the clinical work-flow, which allow data to be used for a wide variety of applications (e.g. quality management, clinical research, clinic management). The presence of incompatible documentation software often complicates the realization of these goals. Implementation of new documentation tools therefore should consider flexibility and multiple-use of data as primary design goals. In the presented paper requirements for flexible documentation tools are introduced. The Entity-Attribute-Value-Model is described as a possible means of implementation. Practical experiences made with a prototype application are reported.

  20. Developing Corrosion Prevention Coating Solutions for the Canadian SCWR Concept

    NASA Astrophysics Data System (ADS)

    Huang, Xiao

    2016-02-01

    The development of coating materials and processes was carried out with the objective to reduce material degradation in supercritical water. Based on the test results of bulk coating alloys (FeCrAlY and NiCrAl), two coating processes, plasma spray of dense NiCrAlY and pack aluminizing, have been developed to apply coatings to candidate stainless steels and Ni-based alloys. The SCW test results and microstructure characterization of both coating alloys and coated candidate alloys are presented in this short paper.