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Sample records for evolutionary constraints permeate

  1. Functional Sites Induce Long-Range Evolutionary Constraints in Enzymes.

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    Benjamin R Jack

    2016-05-01

    Full Text Available Functional residues in proteins tend to be highly conserved over evolutionary time. However, to what extent functional sites impose evolutionary constraints on nearby or even more distant residues is not known. Here, we report pervasive conservation gradients toward catalytic residues in a dataset of 524 distinct enzymes: evolutionary conservation decreases approximately linearly with increasing distance to the nearest catalytic residue in the protein structure. This trend encompasses, on average, 80% of the residues in any enzyme, and it is independent of known structural constraints on protein evolution such as residue packing or solvent accessibility. Further, the trend exists in both monomeric and multimeric enzymes and irrespective of enzyme size and/or location of the active site in the enzyme structure. By contrast, sites in protein-protein interfaces, unlike catalytic residues, are only weakly conserved and induce only minor rate gradients. In aggregate, these observations show that functional sites, and in particular catalytic residues, induce long-range evolutionary constraints in enzymes.

  2. Peculiarities in the distribution of galactic Wolf-Rayet stars: constraints on evolutionary scenarios

    International Nuclear Information System (INIS)

    Gomez, A.; Lortet, M.-C.; Pitault, A.

    1981-01-01

    The re-examination of the spatial distribution of 158 Wolf-Rayet stars in the Galaxy may help to define different breeds of Wolf-Rayet stars and put constraints on possible evolutionary scenarios. (Auth.)

  3. Constrained Optimization Based on Hybrid Evolutionary Algorithm and Adaptive Constraint-Handling Technique

    DEFF Research Database (Denmark)

    Wang, Yong; Cai, Zixing; Zhou, Yuren

    2009-01-01

    A novel approach to deal with numerical and engineering constrained optimization problems, which incorporates a hybrid evolutionary algorithm and an adaptive constraint-handling technique, is presented in this paper. The hybrid evolutionary algorithm simultaneously uses simplex crossover and two...... mutation operators to generate the offspring population. Additionally, the adaptive constraint-handling technique consists of three main situations. In detail, at each situation, one constraint-handling mechanism is designed based on current population state. Experiments on 13 benchmark test functions...... and four well-known constrained design problems verify the effectiveness and efficiency of the proposed method. The experimental results show that integrating the hybrid evolutionary algorithm with the adaptive constraint-handling technique is beneficial, and the proposed method achieves competitive...

  4. Assessing facial attractiveness: individual decisions and evolutionary constraints

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    Kocsor, Ferenc; Feldmann, Adam; Bereczkei, Tamas; Kállai, János

    2013-01-01

    Background Several studies showed that facial attractiveness, as a highly salient social cue, influences behavioral responses. It has also been found that attractive faces evoke distinctive neural activation compared to unattractive or neutral faces. Objectives Our aim was to design a face recognition task where individual preferences for facial cues are controlled for, and to create conditions that are more similar to natural circumstances in terms of decision making. Design In an event-related functional magnetic resonance imaging (fMRI) experiment, subjects were shown attractive and unattractive faces, categorized on the basis of their own individual ratings. Results Statistical analysis of all subjects showed elevated brain activation for attractive opposite-sex faces in contrast to less attractive ones in regions that previously have been reported to show enhanced activation with increasing attractiveness level (e.g. the medial and superior occipital gyri, fusiform gyrus, precentral gyrus, and anterior cingular cortex). Besides these, females showed additional brain activation in areas thought to be involved in basic emotions and desires (insula), detection of facial emotions (superior temporal gyrus), and memory retrieval (hippocampus). Conclusions From these data, we speculate that because of the risks involving mate choice faced by women during evolutionary times, selection might have preferred the development of an elaborated neural system in females to assess the attractiveness and social value of male faces. PMID:24693356

  5. Assessing facial attractiveness: individual decisions and evolutionary constraints

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    Ferenc Kocsor

    2013-10-01

    Full Text Available Background: Several studies showed that facial attractiveness, as a highly salient social cue, influences behavioral responses. It has also been found that attractive faces evoke distinctive neural activation compared to unattractive or neutral faces. Objectives: Our aim was to design a face recognition task where individual preferences for facial cues are controlled for, and to create conditions that are more similar to natural circumstances in terms of decision making. Design: In an event-related functional magnetic resonance imaging (fMRI experiment, subjects were shown attractive and unattractive faces, categorized on the basis of their own individual ratings. Results: Statistical analysis of all subjects showed elevated brain activation for attractive opposite-sex faces in contrast to less attractive ones in regions that previously have been reported to show enhanced activation with increasing attractiveness level (e.g. the medial and superior occipital gyri, fusiform gyrus, precentral gyrus, and anterior cingular cortex. Besides these, females showed additional brain activation in areas thought to be involved in basic emotions and desires (insula, detection of facial emotions (superior temporal gyrus, and memory retrieval (hippocampus. Conclusions: From these data, we speculate that because of the risks involving mate choice faced by women during evolutionary times, selection might have preferred the development of an elaborated neural system in females to assess the attractiveness and social value of male faces.

  6. NEUTRON STAR MASS–RADIUS CONSTRAINTS USING EVOLUTIONARY OPTIMIZATION

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, A. L.; Morsink, S. M. [Department of Physics, University of Alberta, 4-183 CCIS, Edmonton, AB, T6G 2E1 (Canada); Fiege, J. D. [Department of Physics and Astronomy, University of Manitoba, Winnipeg, MB, R3T 2N2 (Canada); Leahy, D. A. [Department of Physics, University of Calgary, 2500 University Drive NW, Calgary, AB, T2N 1N4 (Canada)

    2016-12-20

    The equation of state of cold supra-nuclear-density matter, such as in neutron stars, is an open question in astrophysics. A promising method for constraining the neutron star equation of state is modeling pulse profiles of thermonuclear X-ray burst oscillations from hot spots on accreting neutron stars. The pulse profiles, constructed using spherical and oblate neutron star models, are comparable to what would be observed by a next-generation X-ray timing instrument like ASTROSAT , NICER , or a mission similar to LOFT . In this paper, we showcase the use of an evolutionary optimization algorithm to fit pulse profiles to determine the best-fit masses and radii. By fitting synthetic data, we assess how well the optimization algorithm can recover the input parameters. Multiple Poisson realizations of the synthetic pulse profiles, constructed with 1.6 million counts and no background, were fitted with the Ferret algorithm to analyze both statistical and degeneracy-related uncertainty and to explore how the goodness of fit depends on the input parameters. For the regions of parameter space sampled by our tests, the best-determined parameter is the projected velocity of the spot along the observer’s line of sight, with an accuracy of ≤3% compared to the true value and with ≤5% statistical uncertainty. The next best determined are the mass and radius; for a neutron star with a spin frequency of 600 Hz, the best-fit mass and radius are accurate to ≤5%, with respective uncertainties of ≤7% and ≤10%. The accuracy and precision depend on the observer inclination and spot colatitude, with values of ∼1% achievable in mass and radius if both the inclination and colatitude are ≳60°.

  7. How Do Severe Constraints Affect the Search Ability of Multiobjective Evolutionary Algorithms in Water Resources?

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    Clarkin, T. J.; Kasprzyk, J. R.; Raseman, W. J.; Herman, J. D.

    2015-12-01

    This study contributes a diagnostic assessment of multiobjective evolutionary algorithm (MOEA) search on a set of water resources problem formulations with different configurations of constraints. Unlike constraints in classical optimization modeling, constraints within MOEA simulation-optimization represent limits on acceptable performance that delineate whether solutions within the search problem are feasible. Constraints are relevant because of the emergent pressures on water resources systems: increasing public awareness of their sustainability, coupled with regulatory pressures on water management agencies. In this study, we test several state-of-the-art MOEAs that utilize restricted tournament selection for constraint handling on varying configurations of water resources planning problems. For example, a problem that has no constraints on performance levels will be compared with a problem with several severe constraints, and a problem with constraints that have less severe values on the constraint thresholds. One such problem, Lower Rio Grande Valley (LRGV) portfolio planning, has been solved with a suite of constraints that ensure high reliability, low cost variability, and acceptable performance in a single year severe drought. But to date, it is unclear whether or not the constraints are negatively affecting MOEAs' ability to solve the problem effectively. Two categories of results are explored. The first category uses control maps of algorithm performance to determine if the algorithm's performance is sensitive to user-defined parameters. The second category uses run-time performance metrics to determine the time required for the algorithm to reach sufficient levels of convergence and diversity on the solution sets. Our work exploring the effect of constraints will better enable practitioners to define MOEA problem formulations for real-world systems, especially when stakeholders are concerned with achieving fixed levels of performance according to one or

  8. Evolutionary constraints shape caste-specific gene expression across 15 ant species.

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    Morandin, Claire; Mikheyev, Alexander S; Pedersen, Jes Søe; Helanterä, Heikki

    2017-05-01

    Development of polymorphic phenotypes from similar genomes requires gene expression differences. However, little is known about how morph-specific gene expression patterns vary on a broad phylogenetic scale. We hypothesize that evolution of morph-specific gene expression, and consequently morph-specific phenotypic evolution, may be constrained by gene essentiality and the amount of pleiotropic constraints. Here, we use comparative transcriptomics of queen and worker morphs, that is, castes, from 15 ant species to understand the constraints of morph-biased gene expression. In particular, we investigate how measures of evolutionary constraints at the sequence level (expression level, connectivity, and number of gene ontology [GO] terms) correlate with morph-biased expression. Our results show that genes indeed vary in their potential to become morph-biased. The existence of genes that are constrained in becoming caste-biased potentially limits the evolutionary decoupling of the caste phenotypes, that is, it might result in "caste load" occasioning from antagonistic fitness variation, similarly to sexually antagonistic fitness variation between males and females. On the other hand, we suggest that genes under low constraints are released from antagonistic variation and thus more likely to be co-opted for morph specific use. Overall, our results suggest that the factors that affect sequence evolutionary rates and evolution of plastic expression may largely overlap. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

  9. Indirect genetics effects and evolutionary constraint: an analysis of social dominance in red deer, Cervus elaphus.

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    Wilson, A J; Morrissey, M B; Adams, M J; Walling, C A; Guinness, F E; Pemberton, J M; Clutton-Brock, T H; Kruuk, L E B

    2011-04-01

    By determining access to limited resources, social dominance is often an important determinant of fitness. Thus, if heritable, standard theory predicts mean dominance should evolve. However, dominance is usually inferred from the tendency to win contests, and given one winner and one loser in any dyadic contest, the mean proportion won will always equal 0.5. Here, we argue that the apparent conflict between quantitative genetic theory and common sense is resolved by recognition of indirect genetic effects (IGEs). We estimate selection on, and genetic (co)variance structures for, social dominance, in a wild population of red deer Cervus elaphus, on the Scottish island of Rum. While dominance is heritable and positively correlated with lifetime fitness, contest outcomes depend as much on the genes carried by an opponent as on the genotype of a focal individual. We show how this dependency imposes an absolute evolutionary constraint on the phenotypic mean, thus reconciling theoretical predictions with common sense. More generally, we argue that IGEs likely provide a widespread but poorly recognized source of evolutionary constraint for traits influenced by competition. © 2011 The Authors. Journal of Evolutionary Biology © 2011 European Society For Evolutionary Biology.

  10. Molecular Evolutionary Constraints that Determine the Avirulence State of Clostridium botulinum C2 Toxin.

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    Prisilla, A; Prathiviraj, R; Chellapandi, P

    2017-04-01

    Clostridium botulinum (group-III) is an anaerobic bacterium producing C2 toxin along with botulinum neurotoxins. C2 toxin is belonged to binary toxin A family in bacterial ADP-ribosylation superfamily. A structural and functional diversity of binary toxin A family was inferred from different evolutionary constraints to determine the avirulence state of C2 toxin. Evolutionary genetic analyses revealed evidence of C2 toxin cluster evolution through horizontal gene transfer from the phage or plasmid origins, site-specific insertion by gene divergence, and homologous recombination event. It has also described that residue in conserved NAD-binding core, family-specific domain structure, and functional motifs found to predetermine its virulence state. Any mutational changes in these residues destabilized its structure-function relationship. Avirulent mutants of C2 toxin were screened and selected from a crucial site required for catalytic function of C2I and pore-forming function of C2II. We found coevolved amino acid pairs contributing an essential role in stabilization of its local structural environment. Avirulent toxins selected in this study were evaluated by detecting evolutionary constraints in stability of protein backbone structure, folding and conformational dynamic space, and antigenic peptides. We found 4 avirulent mutants of C2I and 5 mutants of C2II showing more stability in their local structural environment and backbone structure with rapid fold rate, and low conformational flexibility at mutated sites. Since, evolutionary constraints-free mutants with lack of catalytic and pore-forming function suggested as potential immunogenic candidates for treating C. botulinum infected poultry and veterinary animals. Single amino acid substitution in C2 toxin thus provides a major importance to understand its structure-function link, not only of a molecule but also of the pathogenesis.

  11. An Adaptive Evolutionary Algorithm for Traveling Salesman Problem with Precedence Constraints

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    Jinmo Sung

    2014-01-01

    Full Text Available Traveling sales man problem with precedence constraints is one of the most notorious problems in terms of the efficiency of its solution approach, even though it has very wide range of industrial applications. We propose a new evolutionary algorithm to efficiently obtain good solutions by improving the search process. Our genetic operators guarantee the feasibility of solutions over the generations of population, which significantly improves the computational efficiency even when it is combined with our flexible adaptive searching strategy. The efficiency of the algorithm is investigated by computational experiments.

  12. Shrimp Feed Formulation via Evolutionary Algorithm with Power Heuristics for Handling Constraints

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    Rosshairy Abd. Rahman

    2017-01-01

    Full Text Available Formulating feed for shrimps represents a challenge to farmers and industry partners. Most previous studies selected from only a small number of ingredients due to cost pressures, even though hundreds of potential ingredients could be used in the shrimp feed mix. Even with a limited number of ingredients, the best combination of the most appropriate ingredients is still difficult to obtain due to various constraint requirements, such as nutrition value and cost. This paper proposes a new operator which we call Power Heuristics, as part of an Evolutionary Algorithm (EA, which acts as a constraint handling technique for the shrimp feed or diet formulation. The operator is able to choose and discard certain ingredients by utilising a specialized search mechanism. The aim is to achieve the most appropriate combination of ingredients. Power Heuristics are embedded in the EA at the early stage of a semirandom initialization procedure. The resulting combination of ingredients, after fulfilling all the necessary constraints, shows that this operator is useful in discarding inappropriate ingredients when a crucial constraint is violated.

  13. Differential Evolutionary Constraints in the Evolution of Chemoreceptors: A Murine and Human Case Study

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    Ricardo D’Oliveira Albanus

    2014-01-01

    Full Text Available Chemoreception is among the most important sensory modalities in animals. Organisms use the ability to perceive chemical compounds in all major ecological activities. Recent studies have allowed the characterization of chemoreceptor gene families. These genes present strikingly high variability in copy numbers and pseudogenization degrees among different species, but the mechanisms underlying their evolution are not fully understood. We have analyzed the functional networks of these genes, their orthologs distribution, and performed phylogenetic analyses in order to investigate their evolutionary dynamics. We have modeled the chemosensory networks and compared the evolutionary constraints of their genes in Mus musculus, Homo sapiens, and Rattus norvegicus. We have observed significant differences regarding the constraints on the orthologous groups and network topologies of chemoreceptors and signal transduction machinery. Our findings suggest that chemosensory receptor genes are less constrained than their signal transducing machinery, resulting in greater receptor diversity and conservation of information processing pathways. More importantly, we have observed significant differences among the receptors themselves, suggesting that olfactory and bitter taste receptors are more conserved than vomeronasal receptors.

  14. Comparison of Multiobjective Evolutionary Algorithms for Operations Scheduling under Machine Availability Constraints

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    M. Frutos

    2013-01-01

    Full Text Available Many of the problems that arise in production systems can be handled with multiobjective techniques. One of those problems is that of scheduling operations subject to constraints on the availability of machines and buffer capacity. In this paper we analyze different Evolutionary multiobjective Algorithms (MOEAs for this kind of problems. We consider an experimental framework in which we schedule production operations for four real world Job-Shop contexts using three algorithms, NSGAII, SPEA2, and IBEA. Using two performance indexes, Hypervolume and R2, we found that SPEA2 and IBEA are the most efficient for the tasks at hand. On the other hand IBEA seems to be a better choice of tool since it yields more solutions in the approximate Pareto frontier.

  15. Characterization of the avian Trojan gene family reveals contrasting evolutionary constraints.

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    Petar Petrov

    Full Text Available "Trojan" is a leukocyte-specific, cell surface protein originally identified in the chicken. Its molecular function has been hypothesized to be related to anti-apoptosis and the proliferation of immune cells. The Trojan gene has been localized onto the Z sex chromosome. The adjacent two genes also show significant homology to Trojan, suggesting the existence of a novel gene/protein family. Here, we characterize this Trojan family, identify homologues in other species and predict evolutionary constraints on these genes. The two Trojan-related proteins in chicken were predicted as a receptor-type tyrosine phosphatase and a transmembrane protein, bearing a cytoplasmic immuno-receptor tyrosine-based activation motif. We identified the Trojan gene family in ten other bird species and found related genes in three reptiles and a fish species. The phylogenetic analysis of the homologues revealed a gradual diversification among the family members. Evolutionary analyzes of the avian genes predicted that the extracellular regions of the proteins have been subjected to positive selection. Such selection was possibly a response to evolving interacting partners or to pathogen challenges. We also observed an almost complete lack of intracellular positively selected sites, suggesting a conserved signaling mechanism of the molecules. Therefore, the contrasting patterns of selection likely correlate with the interaction and signaling potential of the molecules.

  16. Characterization of the avian Trojan gene family reveals contrasting evolutionary constraints.

    Science.gov (United States)

    Petrov, Petar; Syrjänen, Riikka; Smith, Jacqueline; Gutowska, Maria Weronika; Uchida, Tatsuya; Vainio, Olli; Burt, David W

    2015-01-01

    "Trojan" is a leukocyte-specific, cell surface protein originally identified in the chicken. Its molecular function has been hypothesized to be related to anti-apoptosis and the proliferation of immune cells. The Trojan gene has been localized onto the Z sex chromosome. The adjacent two genes also show significant homology to Trojan, suggesting the existence of a novel gene/protein family. Here, we characterize this Trojan family, identify homologues in other species and predict evolutionary constraints on these genes. The two Trojan-related proteins in chicken were predicted as a receptor-type tyrosine phosphatase and a transmembrane protein, bearing a cytoplasmic immuno-receptor tyrosine-based activation motif. We identified the Trojan gene family in ten other bird species and found related genes in three reptiles and a fish species. The phylogenetic analysis of the homologues revealed a gradual diversification among the family members. Evolutionary analyzes of the avian genes predicted that the extracellular regions of the proteins have been subjected to positive selection. Such selection was possibly a response to evolving interacting partners or to pathogen challenges. We also observed an almost complete lack of intracellular positively selected sites, suggesting a conserved signaling mechanism of the molecules. Therefore, the contrasting patterns of selection likely correlate with the interaction and signaling potential of the molecules.

  17. A high-resolution map of human evolutionary constraint using 29 mammals.

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    Lindblad-Toh, Kerstin; Garber, Manuel; Zuk, Or; Lin, Michael F; Parker, Brian J; Washietl, Stefan; Kheradpour, Pouya; Ernst, Jason; Jordan, Gregory; Mauceli, Evan; Ward, Lucas D; Lowe, Craig B; Holloway, Alisha K; Clamp, Michele; Gnerre, Sante; Alföldi, Jessica; Beal, Kathryn; Chang, Jean; Clawson, Hiram; Cuff, James; Di Palma, Federica; Fitzgerald, Stephen; Flicek, Paul; Guttman, Mitchell; Hubisz, Melissa J; Jaffe, David B; Jungreis, Irwin; Kent, W James; Kostka, Dennis; Lara, Marcia; Martins, Andre L; Massingham, Tim; Moltke, Ida; Raney, Brian J; Rasmussen, Matthew D; Robinson, Jim; Stark, Alexander; Vilella, Albert J; Wen, Jiayu; Xie, Xiaohui; Zody, Michael C; Baldwin, Jen; Bloom, Toby; Chin, Chee Whye; Heiman, Dave; Nicol, Robert; Nusbaum, Chad; Young, Sarah; Wilkinson, Jane; Worley, Kim C; Kovar, Christie L; Muzny, Donna M; Gibbs, Richard A; Cree, Andrew; Dihn, Huyen H; Fowler, Gerald; Jhangiani, Shalili; Joshi, Vandita; Lee, Sandra; Lewis, Lora R; Nazareth, Lynne V; Okwuonu, Geoffrey; Santibanez, Jireh; Warren, Wesley C; Mardis, Elaine R; Weinstock, George M; Wilson, Richard K; Delehaunty, Kim; Dooling, David; Fronik, Catrina; Fulton, Lucinda; Fulton, Bob; Graves, Tina; Minx, Patrick; Sodergren, Erica; Birney, Ewan; Margulies, Elliott H; Herrero, Javier; Green, Eric D; Haussler, David; Siepel, Adam; Goldman, Nick; Pollard, Katherine S; Pedersen, Jakob S; Lander, Eric S; Kellis, Manolis

    2011-10-12

    The comparison of related genomes has emerged as a powerful lens for genome interpretation. Here we report the sequencing and comparative analysis of 29 eutherian genomes. We confirm that at least 5.5% of the human genome has undergone purifying selection, and locate constrained elements covering ∼4.2% of the genome. We use evolutionary signatures and comparisons with experimental data sets to suggest candidate functions for ∼60% of constrained bases. These elements reveal a small number of new coding exons, candidate stop codon readthrough events and over 10,000 regions of overlapping synonymous constraint within protein-coding exons. We find 220 candidate RNA structural families, and nearly a million elements overlapping potential promoter, enhancer and insulator regions. We report specific amino acid residues that have undergone positive selection, 280,000 non-coding elements exapted from mobile elements and more than 1,000 primate- and human-accelerated elements. Overlap with disease-associated variants indicates that our findings will be relevant for studies of human biology, health and disease.

  18. Structure-based Markov random field model for representing evolutionary constraints on functional sites.

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    Jeong, Chan-Seok; Kim, Dongsup

    2016-02-24

    Elucidating the cooperative mechanism of interconnected residues is an important component toward understanding the biological function of a protein. Coevolution analysis has been developed to model the coevolutionary information reflecting structural and functional constraints. Recently, several methods have been developed based on a probabilistic graphical model called the Markov random field (MRF), which have led to significant improvements for coevolution analysis; however, thus far, the performance of these models has mainly been assessed by focusing on the aspect of protein structure. In this study, we built an MRF model whose graphical topology is determined by the residue proximity in the protein structure, and derived a novel positional coevolution estimate utilizing the node weight of the MRF model. This structure-based MRF method was evaluated for three data sets, each of which annotates catalytic site, allosteric site, and comprehensively determined functional site information. We demonstrate that the structure-based MRF architecture can encode the evolutionary information associated with biological function. Furthermore, we show that the node weight can more accurately represent positional coevolution information compared to the edge weight. Lastly, we demonstrate that the structure-based MRF model can be reliably built with only a few aligned sequences in linear time. The results show that adoption of a structure-based architecture could be an acceptable approximation for coevolution modeling with efficient computation complexity.

  19. Evolutionary constraints in hind wing shape in Chinese dung beetles (Coleoptera: Scarabaeinae.

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    Ming Bai

    Full Text Available This study examines the evolution hindwing shape in Chinese dung beetle species using morphometric and phylogenetic analyses. Previous studies have analyzed the evolution of wing shape within a single or very few species, or by comparing only a few wing traits. No study has analyzed wing shape evolution of a large number of species, or quantitatively compared morphological variation of wings with proposed phylogenetic relationships. This study examines the morphological variation of hindwings based on 19 landmarks, 119 morphological characters, and 81 beetle species. Only one most parsimonious tree (MPT was found based on 119 wing and body characters. To better understand the possible role of the hindwing in the evolution of Scarabaeinae, additional phylogenetic analyses were proposed based on the only body features (106 characters, wing characters excluded. Two MPT were found based on 106 body characters, and five nodes were collapsed in a strict consensus. There was a strong correlation between the morphometric tree and all phylogenetic trees (r>0.5. Reconstructions of the ancestral wing forms suggest that Scarabaeinae hindwing morphology has not changed substantially over time, but the morphological changes that do occur are focused at the base of the wing. These results suggest that flight has been important since the origin of Scarabaeinae, and that variation in hindwing morphology has been limited by functional constraints. Comparison of metric disparity values and relative evolutionary sequences among Scarabaeinae tribes suggest that the primitive dung beetles had relatively diverse hindwing morphologies, while advanced dung beetles have relatively similar wing morphologies. The strong correlation between the morphometric tree and phylogenetic trees suggest that hindwing features reflect the evolution of whole body morphology and that wing characters are suitable for the phylogenetic analyses. By integrating morphometric and cladistic

  20. Beyond the Pleistocene: Using Phylogeny and Constraint to Inform the Evolutionary Psychology of Human Mating

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    Eastwick, Paul W.

    2009-01-01

    Evolutionary psychologists explore the adaptive function of traits and behaviors that characterize modern Homo sapiens. However, evolutionary psychologists have yet to incorporate the phylogenetic relationship between modern Homo sapiens and humans' hominid and pongid relatives (both living and extinct) into their theorizing. By considering the…

  1. Investigating evolutionary constraints on the detection of threatening stimuli in preschool children.

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    Zsido, Andras N; Deak, Anita; Losonci, Adrienn; Stecina, Diana; Arato, Akos; Bernath, Laszlo

    2018-04-01

    Numerous objects and animals could be threatening, and thus, children learn to avoid them early. Spiders and syringes are among the most common targets of fears and phobias of the modern word. However, they are of different origins: while the former is evolutionary relevant, the latter is not. We sought to investigate the underlying mechanisms that make the quick detection of such stimuli possible and enable the impulse to avoid them in the future. The respective categories of threatening and non-threatening targets were similar in shape, while low-level visual features were controlled. Our results showed that children found threatening cues faster, irrespective of the evolutionary age of the cues. However, they detected non-threatening evolutionary targets faster than non-evolutionary ones. We suggest that the underlying mechanism may be different: general feature detection can account for finding evolutionary threatening cues quickly, while specific features detection is more appropriate for modern threatening stimuli. Copyright © 2018 Elsevier B.V. All rights reserved.

  2. Evolutionary constraints and the neutral theory. [mutation-caused nucleotide substitutions in DNA

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    Jukes, T. H.; Kimura, M.

    1984-01-01

    The neutral theory of molecular evolution postulates that nucleotide substitutions inherently take place in DNA as a result of point mutations followed by random genetic drift. In the absence of selective constraints, the substitution rate reaches the maximum value set by the mutation rate. The rate in globin pseudogenes is about 5 x 10 to the -9th substitutions per site per year in mammals. Rates slower than this indicate the presence of constraints imposed by negative (natural) selection, which rejects and discards deleterious mutations.

  3. Evolutionary Meta-Analysis of Association Studies Reveals Ancient Constraints Affecting Disease Marker Discovery

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    Dudley, Joel T.; Chen, Rong; Sanderford, Maxwell; Butte, Atul J.; Kumar, Sudhir

    2012-01-01

    Genome-wide disease association studies contrast genetic variation between disease cohorts and healthy populations to discover single nucleotide polymorphisms (SNPs) and other genetic markers revealing underlying genetic architectures of human diseases. Despite scores of efforts over the past decade, many reproducible genetic variants that explain substantial proportions of the heritable risk of common human diseases remain undiscovered. We have conducted a multispecies genomic analysis of 5,831 putative human risk variants for more than 230 disease phenotypes reported in 2,021 studies. We find that the current approaches show a propensity for discovering disease-associated SNPs (dSNPs) at conserved genomic positions because the effect size (odds ratio) and allelic P value of genetic association of an SNP relates strongly to the evolutionary conservation of their genomic position. We propose a new measure for ranking SNPs that integrates evolutionary conservation scores and the P value (E-rank). Using published data from a large case-control study, we demonstrate that E-rank method prioritizes SNPs with a greater likelihood of bona fide and reproducible genetic disease associations, many of which may explain greater proportions of genetic variance. Therefore, long-term evolutionary histories of genomic positions offer key practical utility in reassessing data from existing disease association studies, and in the design and analysis of future studies aimed at revealing the genetic basis of common human diseases. PMID:22389448

  4. Chromospherically active stars. VIII - HD 155638 = V792 Herculis: Observational constraints on evolutionary theory

    International Nuclear Information System (INIS)

    Fekel, F.C.

    1991-01-01

    V792 Her is an eclipsing RS CVn binary with an orbital period of 27.54 days whose components have spectral types of K0 III and F2 IV. New spectroscopic observations combined with existing photometry have resulted in masses of 1.47 + or - 0.003 solar mass and 1.41 + or - 0.003 solar mass for the K giant and F star, respectively. Additional fundamental parameters are derived. Standard evolutionary models were specifically computed by VandenBerg (1990) for the two stars. The best fit occurs if the components are somewhat metal poor with Fe/H/ = - 0.46. Ages of about 2.3 x 10 to the 9th yr derived for the two components differ by less than 3 percent. Thus, standard evolutionary models with no convective overshoot are able to fit the observed parameters of stars as massive as 1.45 solar mass. However, a definitive comparison is not yet possible since the metal abundance of the stars is unknown and metal-poor convective-overshoot tracks in this mass range are needed. 35 refs

  5. Deciding to Cooperate in Northern Ghana: Trust as an Evolutionary Constraint Across Cultural Diversity.

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    Acedo-Carmona, Cristina; Gomila, Antoni

    2015-11-27

    The upper-east and northern regions of Ghana offers a unique opportunity to study the influence of evolutionary social dynamics in making cooperation possible, despite cultural differences. These regions are occupied by several distinct ethnic groups, in interaction, such as the Kussasi, Mamprusi, Bimoba, Konkomba, and Fulani. We will report our fieldwork related to how cooperation takes places there, both within each group and among people from the different groups. Methods included personal networks of cooperation (ego networks), interviews and analysis of group contexts. The most important result is that, while each ethnic group may differ in terms of family and clan structure, a similar pattern can be found in all of them, of cooperation structured around small groups of trust-based close relationships. The study suggests that habitual decisions about cooperation are not strategic or self-interested, but instead are based on unconscious processes sustained by the emotional bonds of trust. These kind of emotional bonds are claimed to be relevant from an evolutionary point of view.

  6. Effects of hybridization and evolutionary constraints on secondary metabolites: the genetic architecture of phenylpropanoids in European populus species.

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    Caseys, Celine; Stritt, Christoph; Glauser, Gaetan; Blanchard, Thierry; Lexer, Christian

    2015-01-01

    The mechanisms responsible for the origin, maintenance and evolution of plant secondary metabolite diversity remain largely unknown. Decades of phenotypic studies suggest hybridization as a key player in generating chemical diversity in plants. Knowledge of the genetic architecture and selective constraints of phytochemical traits is key to understanding the effects of hybridization on plant chemical diversity and ecological interactions. Using the European Populus species P. alba (White poplar) and P. tremula (European aspen) and their hybrids as a model, we examined levels of inter- and intraspecific variation, heritabilities, phenotypic correlations, and the genetic architecture of 38 compounds of the phenylpropanoid pathway measured by liquid chromatography and mass spectrometry (UHPLC-MS). We detected 41 quantitative trait loci (QTL) for chlorogenic acids, salicinoids and flavonoids by genetic mapping in natural hybrid crosses. We show that these three branches of the phenylpropanoid pathway exhibit different geographic patterns of variation, heritabilities, and genetic architectures, and that they are affected differently by hybridization and evolutionary constraints. Flavonoid abundances present high species specificity, clear geographic structure, and strong genetic determination, contrary to salicinoids and chlorogenic acids. Salicinoids, which represent important defence compounds in Salicaceae, exhibited pronounced genetic correlations on the QTL map. Our results suggest that interspecific phytochemical differentiation is concentrated in downstream sections of the phenylpropanoid pathway. In particular, our data point to glycosyltransferase enzymes as likely targets of rapid evolution and interspecific differentiation in the 'model forest tree' Populus.

  7. Effects of hybridization and evolutionary constraints on secondary metabolites: the genetic architecture of phenylpropanoids in European populus species.

    Directory of Open Access Journals (Sweden)

    Celine Caseys

    Full Text Available The mechanisms responsible for the origin, maintenance and evolution of plant secondary metabolite diversity remain largely unknown. Decades of phenotypic studies suggest hybridization as a key player in generating chemical diversity in plants. Knowledge of the genetic architecture and selective constraints of phytochemical traits is key to understanding the effects of hybridization on plant chemical diversity and ecological interactions. Using the European Populus species P. alba (White poplar and P. tremula (European aspen and their hybrids as a model, we examined levels of inter- and intraspecific variation, heritabilities, phenotypic correlations, and the genetic architecture of 38 compounds of the phenylpropanoid pathway measured by liquid chromatography and mass spectrometry (UHPLC-MS. We detected 41 quantitative trait loci (QTL for chlorogenic acids, salicinoids and flavonoids by genetic mapping in natural hybrid crosses. We show that these three branches of the phenylpropanoid pathway exhibit different geographic patterns of variation, heritabilities, and genetic architectures, and that they are affected differently by hybridization and evolutionary constraints. Flavonoid abundances present high species specificity, clear geographic structure, and strong genetic determination, contrary to salicinoids and chlorogenic acids. Salicinoids, which represent important defence compounds in Salicaceae, exhibited pronounced genetic correlations on the QTL map. Our results suggest that interspecific phytochemical differentiation is concentrated in downstream sections of the phenylpropanoid pathway. In particular, our data point to glycosyltransferase enzymes as likely targets of rapid evolution and interspecific differentiation in the 'model forest tree' Populus.

  8. Contrasting patterns of evolutionary constraint and novelty revealed by comparative sperm proteomic analysis in Lepidoptera.

    Science.gov (United States)

    Whittington, Emma; Forsythe, Desiree; Borziak, Kirill; Karr, Timothy L; Walters, James R; Dorus, Steve

    2017-12-02

    Rapid evolution is a hallmark of reproductive genetic systems and arises through the combined processes of sequence divergence, gene gain and loss, and changes in gene and protein expression. While studies aiming to disentangle the molecular ramifications of these processes are progressing, we still know little about the genetic basis of evolutionary transitions in reproductive systems. Here we conduct the first comparative analysis of sperm proteomes in Lepidoptera, a group that exhibits dichotomous spermatogenesis, in which males produce a functional fertilization-competent sperm (eupyrene) and an incompetent sperm morph lacking nuclear DNA (apyrene). Through the integrated application of evolutionary proteomics and genomics, we characterize the genomic patterns potentially associated with the origination and evolution of this unique spermatogenic process and assess the importance of genetic novelty in Lepidopteran sperm biology. Comparison of the newly characterized Monarch butterfly (Danaus plexippus) sperm proteome to those of the Carolina sphinx moth (Manduca sexta) and the fruit fly (Drosophila melanogaster) demonstrated conservation at the level of protein abundance and post-translational modification within Lepidoptera. In contrast, comparative genomic analyses across insects reveals significant divergence at two levels that differentiate the genetic architecture of sperm in Lepidoptera from other insects. First, a significant reduction in orthology among Monarch sperm genes relative to the remainder of the genome in non-Lepidopteran insect species was observed. Second, a substantial number of sperm proteins were found to be specific to Lepidoptera, in that they lack detectable homology to the genomes of more distantly related insects. Lastly, the functional importance of Lepidoptera specific sperm proteins is broadly supported by their increased abundance relative to proteins conserved across insects. Our results identify a burst of genetic novelty

  9. Geographical gradients in selection can reveal genetic constraints for evolutionary responses to ocean acidification.

    Science.gov (United States)

    Gaitán-Espitia, Juan Diego; Marshall, Dustin; Dupont, Sam; Bacigalupe, Leonardo D; Bodrossy, Levente; Hobday, Alistair J

    2017-02-01

    Geographical gradients in selection can shape different genetic architectures in natural populations, reflecting potential genetic constraints for adaptive evolution under climate change. Investigation of natural pH/pCO 2 variation in upwelling regions reveals different spatio-temporal patterns of natural selection, generating genetic and phenotypic clines in populations, and potentially leading to local adaptation, relevant to understanding effects of ocean acidification (OA). Strong directional selection, associated with intense and continuous upwellings, may have depleted genetic variation in populations within these upwelling regions, favouring increased tolerances to low pH but with an associated cost in other traits. In contrast, diversifying or weak directional selection in populations with seasonal upwellings or outside major upwelling regions may have resulted in higher genetic variances and the lack of genetic correlations among traits. Testing this hypothesis in geographical regions with similar environmental conditions to those predicted under climate change will build insights into how selection may act in the future and how populations may respond to stressors such as OA. © 2017 The Author(s).

  10. C7 vertebra homeotic transformation in domestic dogs - are Pug dogs breaking mammalian evolutionary constraints?

    Science.gov (United States)

    Brocal, J; De Decker, S; José-López, R; Manzanilla, E G; Penderis, J; Stalin, C; Bertram, S; Schoenebeck, J J; Rusbridge, C; Fitzpatrick, N; Gutierrez-Quintana, R

    2018-05-14

    The number of cervical vertebrae in mammals is almost constant at seven, regardless of their neck length, implying that there is selection against variation in this number. Homebox (Hox) genes are involved in this evolutionary mammalian conservation, and homeotic transformation of cervical into thoracic vertebrae (cervical ribs) is a common phenotypic abnormality when Hox gene expression is altered. This relatively benign phenotypic change can be associated with fatal traits in humans. Mutations in genes upstream of Hox, inbreeding and stressors during organogenesis can also cause cervical ribs. The aim of this study was to describe the prevalence of cervical ribs in a large group of domestic dogs of different breeds, and explore a possible relation with other congenital vertebral malformations (CVMs) in the breed with the highest prevalence of cervical ribs. By phenotyping we hoped to give clues as to the underlying genetic causes. Twenty computed tomography studies from at least two breeds belonging to each of the nine groups recognized by the Federation Cynologique Internationale, including all the brachycephalic 'screw-tailed' breeds that are known to be overrepresented for CVMs, were reviewed. The Pug dog was more affected by cervical ribs than any other breed (46%; P < 0.001), and was selected for further analysis. No association was found between the presence of cervical ribs and vertebral body formation defect, bifid spinous process, caudal articular process hypoplasia/aplasia and an abnormal sacrum, which may infer they have a different aetiopathogenesis. However, Pug dogs with cervical ribs were more likely to have a transitional thoraco-lumbar vertebra (P = 0.041) and a pre-sacral vertebral count of 26 (P < 0.001). Higher C7/T1 dorsal spinous processes ratios were associated with the presence of cervical ribs (P < 0.001), supporting this is a true homeotic transformation. Relaxation of the stabilizing selection has likely occurred, and

  11. Evolutionary constraint and disease associations of post-translational modification sites in human genomes.

    Directory of Open Access Journals (Sweden)

    Jüri Reimand

    2015-01-01

    Full Text Available Interpreting the impact of human genome variation on phenotype is challenging. The functional effect of protein-coding variants is often predicted using sequence conservation and population frequency data, however other factors are likely relevant. We hypothesized that variants in protein post-translational modification (PTM sites contribute to phenotype variation and disease. We analyzed fraction of rare variants and non-synonymous to synonymous variant ratio (Ka/Ks in 7,500 human genomes and found a significant negative selection signal in PTM regions independent of six factors, including conservation, codon usage, and GC-content, that is widely distributed across tissue-specific genes and function classes. PTM regions are also enriched in known disease mutations, suggesting that PTM variation is more likely deleterious. PTM constraint also affects flanking sequence around modified residues and increases around clustered sites, indicating presence of functionally important short linear motifs. Using target site motifs of 124 kinases, we predict that at least ∼180,000 motif-breaker amino acid residues that disrupt PTM sites when substituted, and highlight kinase motifs that show specific negative selection and enrichment of disease mutations. We provide this dataset with corresponding hypothesized mechanisms as a community resource. As an example of our integrative approach, we propose that PTPN11 variants in Noonan syndrome aberrantly activate the protein by disrupting an uncharacterized cluster of phosphorylation sites. Further, as PTMs are molecular switches that are modulated by drugs, we study mutated binding sites of PTM enzymes in disease genes and define a drug-disease network containing 413 novel predicted disease-gene links.

  12. What affects the predictability of evolutionary constraints using a G-matrix? The relative effects of modular pleiotropy and mutational correlation.

    Science.gov (United States)

    Chebib, Jobran; Guillaume, Frédéric

    2017-10-01

    Phenotypic traits do not always respond to selection independently from each other and often show correlated responses to selection. The structure of a genotype-phenotype map (GP map) determines trait covariation, which involves variation in the degree and strength of the pleiotropic effects of the underlying genes. It is still unclear, and debated, how much of that structure can be deduced from variational properties of quantitative traits that are inferred from their genetic (co) variance matrix (G-matrix). Here we aim to clarify how the extent of pleiotropy and the correlation among the pleiotropic effects of mutations differentially affect the structure of a G-matrix and our ability to detect genetic constraints from its eigen decomposition. We show that the eigenvectors of a G-matrix can be predictive of evolutionary constraints when they map to underlying pleiotropic modules with correlated mutational effects. Without mutational correlation, evolutionary constraints caused by the fitness costs associated with increased pleiotropy are harder to infer from evolutionary metrics based on a G-matrix's geometric properties because uncorrelated pleiotropic effects do not affect traits' genetic correlations. Correlational selection induces much weaker modular partitioning of traits' genetic correlations in absence then in presence of underlying modular pleiotropy. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

  13. On Diffusion and Permeation

    KAUST Repository

    Peppin, Stephen S. L.

    2009-01-01

    concentrations they form a nearly rigid porous glass through which the fluid permeates. The theoretically determined pressure drop is nonlinear in the diffusion regime and linear in the permeation regime, in quantitative agreement with experimental measurements

  14. Permeation through graphene ripples

    Science.gov (United States)

    Liang, Tao; He, Guangyu; Wu, Xu; Ren, Jindong; Guo, Hongxuan; Kong, Yuhan; Iwai, Hideo; Fujita, Daisuke; Gao, Hongjun; Guo, Haiming; Liu, Yingchun; Xu, Mingsheng

    2017-06-01

    Real graphene sheets show limited anti-permeation performance deviating from the ideally flat honeycomb carbon lattice that is impermeable to gases. Ripples in graphene are prevalent and they could significantly influence carrier transport. However, little attention has been paid to the role of ripples in the permeation properties of graphene. Here, we report that gases can permeate through graphene ripples at room temperature. The feasibility of gas permeation through graphene ripples is determined by detecting the initial oxidation sites of Cu surface covered with isolated graphene domain. Nudged elastic band (NEB) calculations demonstrate that the oxygen atom permeation occurs via the formation of C-O-C bond, in which process the energy barrier through the rippled graphene lattice is much smaller than that through a flat graphene lattice, rendering permeation through ripples more favorable. Combining with the recent advances in atoms intercalation between graphene and metal substrate for transfer-free and electrically insulated graphene, this discovery provides new perspectives regarding graphene’s limited anti-permeation performance and evokes for rational design of graphene-based encapsulation for barrier and selective gas separation applications through ripple engineering.

  15. Tritium permeation through iron

    International Nuclear Information System (INIS)

    Hagi, Hideki; Hayashi, Yasunori

    1989-01-01

    An experimental method for measuring diffusion coefficients and permeation rates of tritium in metals around room temperature has been established, and their values in iron have been obtained by using the method. Permeation rates of tritium and hydrogen through iron were measured by the electrochemical method in which a tritiated aqueous solution was used as a cathodic electrolyte. Tritium and hydrogen were introduced from one side of a membrane specimen by cathodic polarization, while at the other side of the specimen the permeating tritium and hydrogen were extracted by potentiostatical ionization. The amount of permeated hydrogen was obtained by integrating the anodic current, and that of tritium was determined by measuring the radioactivity of the electrolyte sampled from the extraction side. Diffusion coefficients of tritium (D T ) and hydrogen (D H ) were determined from the time lag of tritium and hydrogen permeation. D T =9x10 -10 m 2 /s and D H =4x10 -9 m 2 /s at 286 K for annealed iron specimens. These values of D T and D H were compared with the previous data of the diffusion coefficients of hydrogen and deuterium, and the isotope effect in diffusion was discussed. (orig.)

  16. On Diffusion and Permeation

    KAUST Repository

    Peppin, Stephen S. L.

    2009-01-01

    Diffusion and permeation are discussed within the context of irreversible thermodynamics. A new expression for the generalized Stokes-Einstein equation is obtained which links the permeability to the diffusivity of a two-component solution and contains the poroelastic Biot-Willis coefficient. The theory is illustrated by predicting the concentration and pressure profiles during the filtration of a protein solution. At low concentrations the proteins diffuse independently while at higher concentrations they form a nearly rigid porous glass through which the fluid permeates. The theoretically determined pressure drop is nonlinear in the diffusion regime and linear in the permeation regime, in quantitative agreement with experimental measurements. © 2009 Walter de Gruyter, Berlin, New York.

  17. Simplified tritium permeation model

    International Nuclear Information System (INIS)

    Longhurst, G.R.

    1993-01-01

    In this model I seek to provide a simplified approach to solving permeation problems addressed by TMAP4. I will assume that there are m one-dimensional segments with thickness L i , i = 1, 2, hor-ellipsis, m, joined in series with an implantation flux, J i , implanting at the single depth, δ, in the first segment. From material properties and heat transfer considerations, I calculate temperatures at each face of each segment, and from those temperatures I find local diffusivities and solubilities. I assume recombination coefficients K r1 and K r2 are known at the upstream and downstream faces, respectively, but the model will generate Baskes recombination coefficient values on demand. Here I first develop the steady-state concentration equations and then show how trapping considerations can lead to good estimates of permeation transient times

  18. Tritium permeation and recovery

    International Nuclear Information System (INIS)

    Bond, R.A.; Hamilton, A.M.

    1987-01-01

    The paper is an appendix to a study of the reactor relevance of the NET design concept. The latter study examines whether the technologies and design principles proposed for NET can be directly extrapolated to a demonstration (DEMO) reactor. In this appendix, tritium transport in the DEMO breeding blanket is considered with emphasis on the permeation rate from the lithium-lead breeder into the coolant. A computational model used to calculate the tritium transport in the breeder blanket is described. Results are reported for the tritium transport in the NET/INTOR type blanket as well as the DEMO blanket in order to provide a comparison. In addition, results are presented for the helium coolant tritium extraction analysis. (U.K.)

  19. In-pile tritium permeation experiment

    International Nuclear Information System (INIS)

    Longhurst, G.R.; Miller, L.G.; Watts, K.D.; Kershner, C.J.; Rogers, M.L.

    1982-01-01

    The experiments in progress are examining various aspects of the permeation of hydrogen isotopes through fusion materials. Of particular importance will be the measurement of permeation due to ion implantation in the presence of a neutron radiation field. Theoretical and early experimental results for these experiments have suggested that sufficient tritium will permeate fusion reactor interior structures that development of a permeation barrier will be needed. (orig.)

  20. In-pile tritium permeation experiment

    Energy Technology Data Exchange (ETDEWEB)

    Longhurst, G.R.; Miller, L.G.; Watts, K.D. (Idaho National Engineering Lab., Idaho Falls (USA)); Kershner, C.J.; Rogers, M.L. (Monsanto Research Corp., Miamisburg, OH (USA). Mound Facility)

    The experiments in progress are examining various aspects of the permeation of hydrogen isotopes through fusion materials. Of particular importance will be the measurement of permeation due to ion implantation in the presence of a neutron radiation field. Theoretical and early experimental results for these experiments have suggested that sufficient tritium will permeate fusion reactor interior structures that development of a permeation barrier will be needed.

  1. Assessment of permeation of lipoproteins in human carotid tissue

    Science.gov (United States)

    Ghosn, Mohamad G.; Syed, Saba H.; Leba, Michael; Morrisett, Joel D.; Tuchin, Valery V.; Larin, Kirill V.

    2010-02-01

    Cardiovascular disease is among the leading causes of death in the United States. Specifically, atherosclerosis is an increasingly devastating contributor to the tally and has been found to be a byproduct of arterial permeability irregularities in regards to lipoprotein penetration. To further explore arterial physiology and molecular transport, the imaging technique of Optical Coherence Tomography (OCT) was employed. With OCT, the permeation of glucose (MW = 180 Da), low density lipoprotein (LDL; MW = 2.1 × 106 Da), and high density lipoprotein (HDL; MW = 2.5 × 105 Da) in human carotid tissue was studied to determine the effect of different molecular characteristics on permeation in atherosclerotic tissues. The permeability rates calculated from the diffusion of the molecular agents into the abnormal carotid tissue samples is compared to those of normal, healthy tissue. The results show that in the abnormal tissue, the permeation of agents correlate to the size constraints. The larger molecules of LDL diffuse the slowest, while the smallest molecules of glucose diffuse the fastest. However, in normal tissue, LDL permeates at a faster rate than the other two agents, implying the existence of a transport mechanism that facilitates the passage of LDL molecules. These results highlight the capability of OCT as a sensitive and specific imaging technique as well as provide significant information to the understanding of atherosclerosis and its effect on tissue properties.

  2. Evolutionary constrained optimization

    CERN Document Server

    Deb, Kalyanmoy

    2015-01-01

    This book makes available a self-contained collection of modern research addressing the general constrained optimization problems using evolutionary algorithms. Broadly the topics covered include constraint handling for single and multi-objective optimizations; penalty function based methodology; multi-objective based methodology; new constraint handling mechanism; hybrid methodology; scaling issues in constrained optimization; design of scalable test problems; parameter adaptation in constrained optimization; handling of integer, discrete and mix variables in addition to continuous variables; application of constraint handling techniques to real-world problems; and constrained optimization in dynamic environment. There is also a separate chapter on hybrid optimization, which is gaining lots of popularity nowadays due to its capability of bridging the gap between evolutionary and classical optimization. The material in the book is useful to researchers, novice, and experts alike. The book will also be useful...

  3. Relative size of the eye and orbit: an evolutionary and craniofacial constraint model for examining the etiology and disparate incidence of juvenile-onset myopia in humans.

    Science.gov (United States)

    Masters, Michael P

    2012-05-01

    The principal aim of this research is to provide a new model for investigating myopia in humans, and contribute to an understanding of the degree to which modern variation and evolutionary change in orbital and overall craniofacial morphology may help explain the common eye form association with this condition. Recent research into long and short-term evolution of the human orbit reveals a number of changes in this feature, and particularly since the Upper Paleolithic. These include a reduction in orbital depth, a decrease in anterior projection of the upper and lower orbital margins, and most notably, a reduction in orbital volume since the Holocene in East Asia. Reduced orbital volume in this geographic region could exacerbate an existing trend in recent hominin evolution toward larger eyes in smaller orbits, and may help explain the unusually high frequency of myopia in East Asian populations. The objective of the current study is to test a null hypothesis of no relationship between a ratio of orbit to eye volume and spherical equivalent refractive error (SER) in a sample of Chinese adults, and examine how relative size of the eye within the orbit relates to SER between the sexes and across the sample population. Analysis of the orbit, eye, and SER reveals a strong relationship between relative size of the eye within the orbit and the severity of myopic refractive error. An orbit/eye ratio of 3 for females and 3.5 for males (or an eye that occupies approximately 34% and 29% of the orbit, respectively), designates a clear threshold at which myopia develops, and becomes progressively worse as the eye continues to occupy a greater proportion of the orbital cavity. These results indicate that relative size of the eye within the orbit is an important factor in the development of myopia, and suggests that individuals with large eyes in small orbits lack space for adequate development of ocular tissues, leading to compression and distortion of the lithesome globe

  4. Hydrogen permeation preventive structural materials

    International Nuclear Information System (INIS)

    Fukushima, Kimichika; Nakahigashi, Shigeo; Imura, Masashi; Terasawa, Michitaka; Ebisawa, Katsuyuki.

    1986-01-01

    Purpose: To provide highly practical wall materials for use in thermonuclear reactors capable of effectively preventing the permeation of hydrogen isotopes such as tritium thereby preventing the contamination of coolants. Constitution: Helium gas is injected into or at the surface of base materials comprising stainless steel plates to form a helium gas region. Alternatively, boron, nitrogen or the compound thereof having a greater helium forming nuclear reaction cross section than that of the base materials is mixed or injected into the base material to form the helium gas region through (n,α) reaction under neutron irradiation. Since the helium gas region constitutes a diffusion barrier for the tritium as the hydrogen isotope, the permeation amount of tritium is significantly suppressed. Helium gas bubbles or lattice defects are formed in the helium gas region under the neutron irradiation, by which the hydrogen isotope capturing effect can also be effected. In this way, permeation of the hydrogen isotope, contamination of the coolants, etc. can be prevented to provide great practical effectives. (Kawakami, Y.)

  5. DEEP MIPS OBSERVATIONS OF THE IC 348 NEBULA: CONSTRAINTS ON THE EVOLUTIONARY STATE OF ANEMIC CIRCUMSTELLAR DISKS AND THE PRIMORDIAL-TO-DEBRIS DISK TRANSITION

    International Nuclear Information System (INIS)

    Currie, Thayne; Kenyon, Scott J.

    2009-01-01

    We describe new, deep MIPS photometry and new high signal-to-noise optical spectroscopy of the 2.5 Myr old IC 348 Nebula. To probe the properties of the IC 348 disk population, we combine these data with previous optical/infrared photometry and spectroscopy to identify stars with gas accretion, to examine their mid-IR colors, and to model their spectral energy distributions. IC 348 contains many sources in different evolutionary states, including protostars and stars surrounded by primordial disks, two kinds of transitional disks, and debris disks. Most disks surrounding early/intermediate spectral-type stars (>1.4 M sun at 2.5 Myr) are debris disks; most disks surrounding solar and subsolar-mass stars are primordial disks. At the 1-2 σ level, more massive stars also have a smaller frequency of gas accretion and smaller mid-IR luminosities than lower-mass stars. These trends are suggestive of a stellar mass-dependent evolution of disks, where most disks around high/intermediate-mass stars shed their primordial disks on rapid, 2.5 Myr timescales. The frequency of MIPS-detected transitional disks is ∼15%-35% for stars plausibly more massive than 0.5 M sun . The relative frequency of transitional disks in IC 348 compared to that for 1 Myr old Taurus and 5 Myr old NGC 2362 is consistent with a transition timescale that is a significant fraction of the total primordial disk lifetime.

  6. Deuterium permeation through Flibe facing materials

    International Nuclear Information System (INIS)

    Fukada, S.; Anderl, R.A.; Smolik, G.R.

    2004-01-01

    Experiment of deuterium permeation through Ni facing with purified Flibe is being carried out under the Japan-US joint research project (JUPITER-II). The experiment has been proceeding in the following phases; (i) fabrication and assembly of a dual-probe permeation apparatus, (ii) a single-probe Ni/D 2 , permeation experiment without Flibe, (iii) a dual-probe Ar/Ni/D 2 permeation experiment without Flibe, (iv) Flibe chemical purification by HF/H 2 gas bubbling, (v) physical purification by Flibe transport through a porous Ni filter, (vi) Ar/Ni/Flibe/Ni/D 2 permeation experiment using the dual Ni probe, and (vii) Ar/Ni/Flibe/Ni/HT permeation experiment. The present paper describe results until the Ar/Ni/Flibe/Ni/D 2 permeation experiment in detail. (author)

  7. Permeation behavior of deuterium implanted into beryllium

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Hirofumi; Hayashi, Takumi; O' hira, Shigeru; Nishi, Masataka [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-09-01

    Study on Implantation Driven Permeation (IDP) behavior of deuterium through pure beryllium was investigated as a part of the research to predict the tritium permeation through the first wall components ITER (International Thermonuclear Experimental Reactor). The permeation experiments were carried out with two beryllium specimens, one was an unannealed specimen and the other was that annealed at 1173 K. The permeation flux was measured as a function of specimen temperature and incident ion flux. Surface analysis of specimen was also carried out after the permeation experiment. Permeation was observed only with the annealed specimen and no significant permeation was observed with unannealed specimen under the present experimental condition (maximum temperature: 685 K, detection limit: 1x10{sup 13} D atoms/m{sup 2}s). It could be attributed that the intrinsic lattice defects, which act as diffusion preventing site, decreased with the specimen annealing. Based on the result of steady and transient permeation behavior and surface analysis, it was estimated that the deuterium permeation implanted into annealed beryllium was controlled by surface recombination due to the oxide layer on the surface of the permeated side. (author)

  8. Evolutionary constraints on equid domestication: Comparison of flight initiation distances of wild horses (Equus caballus ferus) and plains zebras (Equus quagga).

    Science.gov (United States)

    Brubaker, Alexali S; Coss, Richard G

    2015-11-01

    Habituation to humans was an essential component of horse (Equus caballus ferus) domestication, with the nondomestication of zebras (Equus quagga) possibly reflecting an adaptive constraint on habituation. We present the human hunting hypothesis, arguing that ancestral humans hunted African animals, including zebras, long enough to promote a persistent wariness of humans, whereas a briefer period of hunting horses in Central Asia influenced by glacial cycles was unlikely to produce an equally persistent wariness. An alternative habituation to humans hypothesis, prompted by field observations, posits that zebras can habituate well to nonthreatening humans given sufficient exposure. If so, other factors must account for zebra nondomestication. To examine these hypotheses, we compared the flight initiation distances (FIDs) of wild horses in the United States and plains zebras in Africa to a human approaching on foot (N = 87). We compared the flight behavior of both species at sites with low and high exposure to humans (mean humans/acre = .004 and .209, respectively). Analyses revealed a significant interaction (p = .0001) between equid species and level of human exposure. The mean FIDs of horses (146 m) and zebras (105 m) with low human exposure did not differ appreciably (p = .412), but these distances were substantially longer (p < .0001) than those of horses (17 m) and zebras (37 m) with high human exposure that did differ significantly (p < .0001). The finding that plains zebras habituate less completely to humans than horses do might reflect an adaptive response to historical hunting and partly explain their resistance to domestication. (c) 2015 APA, all rights reserved).

  9. Hydrogen permeation through metallic foils

    International Nuclear Information System (INIS)

    Bernardi, M.I.B.; Rodrigues, J.A.

    1987-01-01

    The process of electrolytic permeation of hydrogen through metallic foils is studied. A double electrolytic cell, in glass, in which the two compartments of reaction are separated by a metallic foil to be studied, was built. As direct result, the hydrogen diffusion coefficient in the metal is obtained. The hydrogen diffusion coefficients in the palladium and, in austenitic stainless steels 304 and 304 L, used in the Angra-1 reactor, were obtained. Samples of stainless steels with and without welding, were used. (Author) [pt

  10. Tritium permeation in fusion reactors: INTOR

    International Nuclear Information System (INIS)

    Baskes, M.I.; Bauer, W.; Kerst, R.A.; Swansiger, W.A.; Wilson, K.L.

    1981-12-01

    Tritium permeation through the first wall of advanced fusion reactors is examined. A fraction of the D-T which bombards the first wall as charge exchange neutral particles will permeate through the first wall and enter the coolant. Calculations of the steady state permeation rate for the US INTOR Tokamak design result in values of less than or equal to 0.002 grams of tritium per day under the most favorable conditions. For unfavorable surface conditions the rate is greater than or equal to 0.1 g/day. The magnitude of these permeation rates is critically dependent on the temperatures and surface conditions of the wall. The introduction of permeation barriers at the wall-coolant interface can significantly reduce permeation rates and hence may be desirable for reactor applications

  11. Water permeation through anion exchange membranes

    Science.gov (United States)

    Luo, Xiaoyan; Wright, Andrew; Weissbach, Thomas; Holdcroft, Steven

    2018-01-01

    An understanding of water permeation through solid polymer electrolyte (SPE) membranes is crucial to offset the unbalanced water activity within SPE fuel cells. We examine water permeation through an emerging class of anion exchange membranes, hexamethyl-p-terphenyl poly (dimethylbenzimidazolium) (HMT-PMBI), and compare it against series of membrane thickness for a commercial anion exchange membrane (AEM), Fumapem® FAA-3, and a series of proton exchange membranes, Nafion®. The HMT-PMBI membrane is found to possess higher water permeabilities than Fumapem® FAA-3 and comparable permeability than Nafion (H+). By measuring water permeation through membranes of different thicknesses, we are able to decouple, for the first time, internal and interfacial water permeation resistances through anion exchange membranes. Permeation resistances on liquid/membrane interface is found to be negligible compared to that for vapor/membrane for both series of AEMs. Correspondingly, the resistance of liquid water permeation is found to be one order of magnitude smaller compared to that of vapor water permeation. HMT-PMBI possesses larger effective internal water permeation coefficient than both Fumapem® FAA-3 and Nafion® membranes (60 and 18% larger, respectively). In contrast, the effective interfacial permeation coefficient of HMT-PMBI is found to be similar to Fumapem® (±5%) but smaller than Nafion®(H+) (by 14%).

  12. Introduction to Evolutionary Algorithms

    CERN Document Server

    Yu, Xinjie

    2010-01-01

    Evolutionary algorithms (EAs) are becoming increasingly attractive for researchers from various disciplines, such as operations research, computer science, industrial engineering, electrical engineering, social science, economics, etc. This book presents an insightful, comprehensive, and up-to-date treatment of EAs, such as genetic algorithms, differential evolution, evolution strategy, constraint optimization, multimodal optimization, multiobjective optimization, combinatorial optimization, evolvable hardware, estimation of distribution algorithms, ant colony optimization, particle swarm opti

  13. Evolutionary Nephrology.

    Science.gov (United States)

    Chevalier, Robert L

    2017-05-01

    Progressive kidney disease follows nephron loss, hyperfiltration, and incomplete repair, a process described as "maladaptive." In the past 20 years, a new discipline has emerged that expands research horizons: evolutionary medicine. In contrast to physiologic (homeostatic) adaptation, evolutionary adaptation is the result of reproductive success that reflects natural selection. Evolutionary explanations for physiologically maladaptive responses can emerge from mismatch of the phenotype with environment or evolutionary tradeoffs. Evolutionary adaptation to a terrestrial environment resulted in a vulnerable energy-consuming renal tubule and a hypoxic, hyperosmolar microenvironment. Natural selection favors successful energy investment strategy: energy is allocated to maintenance of nephron integrity through reproductive years, but this declines with increasing senescence after ~40 years of age. Risk factors for chronic kidney disease include restricted fetal growth or preterm birth (life history tradeoff resulting in fewer nephrons), evolutionary selection for APOL1 mutations (that provide resistance to trypanosome infection, a tradeoff), and modern life experience (Western diet mismatch leading to diabetes and hypertension). Current advances in genomics, epigenetics, and developmental biology have revealed proximate causes of kidney disease, but attempts to slow kidney disease remain elusive. Evolutionary medicine provides a complementary approach by addressing ultimate causes of kidney disease. Marked variation in nephron number at birth, nephron heterogeneity, and changing susceptibility to kidney injury throughout life history are the result of evolutionary processes. Combined application of molecular genetics, evolutionary developmental biology (evo-devo), developmental programming and life history theory may yield new strategies for prevention and treatment of chronic kidney disease.

  14. Gas permeation process for post combustion CO2 capture

    International Nuclear Information System (INIS)

    Pfister, Marc

    2017-01-01

    CO 2 Capture and Storage (CCS) is a promising solution to separate CO 2 from flue gas, to reduce the CO 2 emissions in the atmosphere, and hence to reduce global warming. In CCS, one important constraint is the high additional energy requirement of the different capture processes. That statement is partly explained by the low CO 2 fraction in the inlet flue gas and the high output targets in terms of CO 2 capture and purity (≥90%). Gas permeation across dense membrane can be used in post combustion CO 2 capture. Gas permeation in a dense membrane is ruled by a mass transfer mechanism and separation performance in a dense membrane are characterized by component's effective permeability and selectivity. One of the newest and encouraging type of membrane in terms of separation performance is the facilitated transport membrane. Each particular type of membrane is defined by a specific mass transfer law. The most important difference to the mass transfer behavior in a dense membrane is related to the facilitated transport mechanism and the solution diffusion mechanism and its restrictions and limitations. Permeation flux modelling across a dense membrane is required to perform a post combustion CO 2 capture process simulation. A CO 2 gas permeation separation process is composed of a two-steps membrane process, one drying step and a compression unit. Simulation on the energy requirement and surface area of the different membrane modules in the global system are useful to determine the benefits of using dense membranes in a post combustion CO 2 capture technology. (author)

  15. Implanted-tritium permeation experiments

    International Nuclear Information System (INIS)

    Longhurst, G.R.; Holland, D.F.; Casper, L.A.; Hsu, P.Y.; Miller, L.G.; Schmunk, R.E.; Watts, K.D.; Wilson, C.J.; Kershner, C.J.; Rogers, M.L.

    1982-04-01

    In fusion reactors, charge exchange neutral atoms of tritium coming from the plasma will be implanted into the first wall and other interior structures. EG and G Idaho is conducting two experiments to determine the magnitude of permeation into the coolant streams and the retention of tritium in those structures. One experiment uses an ion gun to implant deuterium. The ion gun will permit measurements to be made for a variety of implantation energies and fluxes. The second experiment utilizes a fission reactor to generate a tritium implantation flux by the 3 He(n,p) 3 H reaction. This experiment will simulate the fusion reactor radiation environment. We also plan to verify a supporting analytical code development program, in progress, by these experiments

  16. Permeation Tests on Polypropylene Fiber Materials

    Science.gov (United States)

    2018-03-16

    Permeation Tests on Polypropylene Fiber Materials Brandy J. White Martin H. Moore Brian J. Melde Laboratory for the Study of Molecular Interfacial...ABSTRACT Permeation Tests on Polypropylene Fiber Materials Brandy J. White, Martin H. Moore, Brian J. Melde Center for Bio/Molecular Science

  17. Evolutionary Nephrology

    Directory of Open Access Journals (Sweden)

    Robert L. Chevalier

    2017-05-01

    Full Text Available Progressive kidney disease follows nephron loss, hyperfiltration, and incomplete repair, a process described as “maladaptive.” In the past 20 years, a new discipline has emerged that expands research horizons: evolutionary medicine. In contrast to physiologic (homeostatic adaptation, evolutionary adaptation is the result of reproductive success that reflects natural selection. Evolutionary explanations for physiologically maladaptive responses can emerge from mismatch of the phenotype with environment or from evolutionary tradeoffs. Evolutionary adaptation to a terrestrial environment resulted in a vulnerable energy-consuming renal tubule and a hypoxic, hyperosmolar microenvironment. Natural selection favors successful energy investment strategy: energy is allocated to maintenance of nephron integrity through reproductive years, but this declines with increasing senescence after ∼40 years of age. Risk factors for chronic kidney disease include restricted fetal growth or preterm birth (life history tradeoff resulting in fewer nephrons, evolutionary selection for APOL1 mutations (which provide resistance to trypanosome infection, a tradeoff, and modern life experience (Western diet mismatch leading to diabetes and hypertension. Current advances in genomics, epigenetics, and developmental biology have revealed proximate causes of kidney disease, but attempts to slow kidney disease remain elusive. Evolutionary medicine provides a complementary approach by addressing ultimate causes of kidney disease. Marked variation in nephron number at birth, nephron heterogeneity, and changing susceptibility to kidney injury throughout the life history are the result of evolutionary processes. Combined application of molecular genetics, evolutionary developmental biology (evo-devo, developmental programming, and life history theory may yield new strategies for prevention and treatment of chronic kidney disease.

  18. Permeation of hydrogen through metal membranes

    International Nuclear Information System (INIS)

    Wienhold, P.; Rota, E.; Waelbroeck, F.; Winter, J.; Banno, Tatsuya.

    1986-08-01

    Experiments show that the permeant flux of hydrogen through a metal membrane at low driving pressures ( r is introduced into the model as a new material constant and the rate equations are given. After the description of the wall pump effect, a variety of different limiting cases are discussed for a symmetrical permeation membrane. This is modified to the asymmetric case and to the influence of particle implantation. The permeation number W turns out to be a dimensionless quantity which characterizes the permeation range and predicts the permeant flux in steady state. (orig.)

  19. Evolutionary thinking

    Science.gov (United States)

    Hunt, Tam

    2014-01-01

    Evolution as an idea has a lengthy history, even though the idea of evolution is generally associated with Darwin today. Rebecca Stott provides an engaging and thoughtful overview of this history of evolutionary thinking in her 2013 book, Darwin's Ghosts: The Secret History of Evolution. Since Darwin, the debate over evolution—both how it takes place and, in a long war of words with religiously-oriented thinkers, whether it takes place—has been sustained and heated. A growing share of this debate is now devoted to examining how evolutionary thinking affects areas outside of biology. How do our lives change when we recognize that all is in flux? What can we learn about life more generally if we study change instead of stasis? Carter Phipps’ book, Evolutionaries: Unlocking the Spiritual and Cultural Potential of Science's Greatest Idea, delves deep into this relatively new development. Phipps generally takes as a given the validity of the Modern Synthesis of evolutionary biology. His story takes us into, as the subtitle suggests, the spiritual and cultural implications of evolutionary thinking. Can religion and evolution be reconciled? Can evolutionary thinking lead to a new type of spirituality? Is our culture already being changed in ways that we don't realize by evolutionary thinking? These are all important questions and Phipps book is a great introduction to this discussion. Phipps is an author, journalist, and contributor to the emerging “integral” or “evolutionary” cultural movement that combines the insights of Integral Philosophy, evolutionary science, developmental psychology, and the social sciences. He has served as the Executive Editor of EnlightenNext magazine (no longer published) and more recently is the co-founder of the Institute for Cultural Evolution, a public policy think tank addressing the cultural roots of America's political challenges. What follows is an email interview with Phipps. PMID:26478766

  20. Evolutionary Demography

    DEFF Research Database (Denmark)

    Levitis, Daniel

    2015-01-01

    of biological and cultural evolution. Demographic variation within and among human populations is influenced by our biology, and therefore by natural selection and our evolutionary background. Demographic methods are necessary for studying populations of other species, and for quantifying evolutionary fitness......Demography is the quantitative study of population processes, while evolution is a population process that influences all aspects of biological organisms, including their demography. Demographic traits common to all human populations are the products of biological evolution or the interaction...

  1. Permeation of deuterium implanted into vanadium alloys

    International Nuclear Information System (INIS)

    Anderl, R.A.; Longhurst, G.R.; Struttmann, D.A.

    1986-05-01

    Permeation of deuterium through the vanadium alloy, V-15Cr-5Ti, was investigated using 3-keV, D 3 + ion beams from a small accelerator. The experiments consisted of measurements of the deuterium reemission and permeation rates as a function of implantation fluence for 0.5-mm thick specimens heated to tempertures from 623 to 823 0 K. Implantation-side surface characterization was made by simultaneous measurements of sputtered ions with a secondary ion mass spectrometer (SIMS). Analyses of these measurements indicate that for the experimental conditions used, the steady-state deuterium permeation flux in V-15Cr-5Ti is approximately 18% of the implantation flux. This corresponds to approximately 1000 times that seen in the ferritic steel, HT-9, under comparable conditions. Measurement of deuterium diffusivity in V-15Cr-5Ti using permeation break-through times indicates D = 1.4 x 10 -8 exp(-.11 eV/kT) (m 2 /s)

  2. Dissolution and permeation characteristics of artemether tablets ...

    African Journals Online (AJOL)

    characterized by delayed drug release but enhanced permeation of the released drug. Keywords: ... and prosopis gum as binders and to consider the relationship between ..... higher tensile strength and higher brittle fracture index compared ...

  3. Proton permeation of lipid bilayers.

    Science.gov (United States)

    Deamer, D W

    1987-10-01

    Proton permeation of the lipid bilayer barrier has two unique features. First, permeability coefficients measured at neutral pH ranges are six to seven orders of magnitude greater than expected from knowledge of other monovalent cations. Second, proton conductance across planar lipid bilayers varies at most by a factor of 10 when pH is varied from near 1 to near 11. Two mechanisms have been proposed to account for this anomalous behavior: proton conductance related to contaminants of lipid bilayers, and proton translocation along transient hydrogen-bonded chains (tHBC) of associated water molecules in the membrane. The weight of evidence suggests that trace contaminants may contribute to proton conductance across planar lipid membranes at certain pH ranges, but cannot account for the anomalous proton flux in liposome systems. Two new results will be reported here which were designed to test the tHBC model. These include measurements of relative proton/potassium permeability in the gramicidin channel, and plots of proton flux against the magnitude of pH gradients. (1) The relative permeabilities of protons and potassium through the gramicidin channel, which contains a single strand of hydrogen-bonded water molecules, were found to differ by at least four orders of magnitude when measured at neutral pH ranges. This result demonstrates that a hydrogen-bonded chain of water molecules can provide substantial discrimination between protons and other cations. It was also possible to calculate that if approximately 7% of bilayer water was present in a transient configuration similar to that of the gramicidin channel, it could account for the measured proton flux. (2) The plot of proton conductance against pH gradient across liposome membranes was superlinear, a result that is consistent with one of three alternative tHBC models for proton conductance described by Nagle elsewhere in this volume.

  4. Permeation of Ionic Liquids through the skin

    Directory of Open Access Journals (Sweden)

    Ana Júlio

    2017-12-01

    Full Text Available Alternative forms of drug delivery such as delivery through the skin, have been developed to explore other routes. However, the incorporation of poorly soluble or partially insoluble drugs into these delivery systems represents a major problem. Ionic liquids (ILs may be incorporated in aqueous, oily or hydroalcoholic solutions and thus, may be used as excipients in drug delivery systems to increase/improve the topical and transdermal drug delivery. However, it is fundamental to consider the cytotoxicity of these salts and it is also crucial to evaluate if these compounds permeate through the skin. Herein, three imidazole-based ILs: [C2mim][Br], [C4mim][Br] and [C6mim][Br], were synthesized and each IL was incorporated within caffeine saturated solutions. Permeation studies of the active (caffeine in these solutions were performed to evaluate the amount of IL that permeated through the porcine ear skin in the presence of the active. To achieve this, gravimetric studies of the receptor compartment were performed. Results showed that the more lipophilic IL [C6mim][Br] presented the highest permeation through the skin. The permeation is dependent upon the size of the alkyl chain of the IL, and as more than 60% of the ILs permeate is it vital to consider the cytotoxicity of these salts when considering their incorporation in topical systems.

  5. Constraint Differentiation

    DEFF Research Database (Denmark)

    Mödersheim, Sebastian Alexander; Basin, David; Viganò, Luca

    2010-01-01

    We introduce constraint differentiation, a powerful technique for reducing search when model-checking security protocols using constraint-based methods. Constraint differentiation works by eliminating certain kinds of redundancies that arise in the search space when using constraints to represent...... results show that constraint differentiation substantially reduces search and considerably improves the performance of OFMC, enabling its application to a wider class of problems....

  6. Evolutionary Expectations

    DEFF Research Database (Denmark)

    Nash, Ulrik William

    2014-01-01

    , they are correlated among people who share environments because these individuals satisfice within their cognitive bounds by using cues in order of validity, as opposed to using cues arbitrarily. Any difference in expectations thereby arise from differences in cognitive ability, because two individuals with identical...... cognitive bounds will perceive business opportunities identically. In addition, because cues provide information about latent causal structures of the environment, changes in causality must be accompanied by changes in cognitive representations if adaptation is to be maintained. The concept of evolutionary......The concept of evolutionary expectations descends from cue learning psychology, synthesizing ideas on rational expectations with ideas on bounded rationality, to provide support for these ideas simultaneously. Evolutionary expectations are rational, but within cognitive bounds. Moreover...

  7. [Evolutionary medicine].

    Science.gov (United States)

    Wjst, M

    2013-12-01

    Evolutionary medicine allows new insights into long standing medical problems. Are we "really stoneagers on the fast lane"? This insight might have enormous consequences and will allow new answers that could never been provided by traditional anthropology. Only now this is made possible using data from molecular medicine and systems biology. Thereby evolutionary medicine takes a leap from a merely theoretical discipline to practical fields - reproductive, nutritional and preventive medicine, as well as microbiology, immunology and psychiatry. Evolutionary medicine is not another "just so story" but a serious candidate for the medical curriculum providing a universal understanding of health and disease based on our biological origin. © Georg Thieme Verlag KG Stuttgart · New York.

  8. Evolutionary Awareness

    Directory of Open Access Journals (Sweden)

    Gregory Gorelik

    2014-10-01

    Full Text Available In this article, we advance the concept of “evolutionary awareness,” a metacognitive framework that examines human thought and emotion from a naturalistic, evolutionary perspective. We begin by discussing the evolution and current functioning of the moral foundations on which our framework rests. Next, we discuss the possible applications of such an evolutionarily-informed ethical framework to several domains of human behavior, namely: sexual maturation, mate attraction, intrasexual competition, culture, and the separation between various academic disciplines. Finally, we discuss ways in which an evolutionary awareness can inform our cross-generational activities—which we refer to as “intergenerational extended phenotypes”—by helping us to construct a better future for ourselves, for other sentient beings, and for our environment.

  9. Evaluation of whey, milk, and delactosed permeates as salt substitutes.

    Science.gov (United States)

    Smith, S T; Metzger, L; Drake, M A

    2016-11-01

    Whey and milk permeates are by-products of high-protein dairy powder manufacture. Previous work has shown that these permeates contribute to salty taste without contributing significantly to sodium content. The objective of this study was to explore the sensory characteristics and compositional analysis of permeates from different milk and whey streams and a low-sodium product application made from them. Skim milk, Cheddar, cottage, and Mozzarella cheese whey permeates were manufactured in triplicate, and delactosed whey permeate was obtained in triplicate. Composition (protein, fat, solids, minerals) was conducted on permeates. Organic acid composition was determined using HPLC. Volatile compounds were extracted from permeates by solid phase microextraction with gas chromatography-mass spectrometry. A trained sensory panel documented sensory attributes of permeates and cream of broccoli soups with and without salt or permeates followed by consumer acceptance testing (n=105) on the soups. Cottage cheese whey permeate contained a higher lactic acid content than other permeates, which has been shown to contribute to a higher salty taste. Cottage cheese whey permeate also contained potato or brothy and caramel flavors and sour and salty tastes, whereas delactosed whey permeate had high intensities of cardboard and beefy or brothy flavors and salty taste. Milk, Cheddar, and Mozzarella cheese whey permeates were characterized by sweet taste and cooked milky flavor. Permeates with higher cardboard flavor had higher levels of aldehydes. All permeates contributed to salty taste and to salty taste perception in soups; although the control soup with added salt was perceived as saltier and was preferred by consumers over permeate soups. Soup with permeate from cottage cheese was the least liked of all soups, likely due to its sour taste. All other permeate soups scored at parity for liking. These results demonstrate the potential for milk, whey, and delactosed permeates from

  10. Tritium permeation barriers for fusion technology

    International Nuclear Information System (INIS)

    Perujo, A.; Forcey, K.

    1994-01-01

    An important issue concerning the safety, feasibility and fueling (i.e., tritium breeding ratio and recovery from the breeding blanket) of a fusion reactor is the possible tritium leakages through the structural materials and in particular through those operating at high temperatures. The control of tritium permeation could be a critical factor in determining the viability of a future fusion power reactor. The formation of tritium permeation barriers to prevent the loss of tritium to the coolant by diffusion though the structural material seems to be the most practical method to minimize such losses. Many authors have discussed the formation of permeation barriers to reduce the leakage of hydrogen isotopes through proposed first wall and structural materials. In general, there are two routes for the formation of such a barrier, namely: the growth of oxide layers (e.g., Cr 2 O 3 , Al 2 O 3 , etc.) or the application of surface coatings. Non-metals are the most promising materials from the point of view of the formation of permeation barriers. Oxides such as Al 2 O 3 or Cr 2 O 3 or carbides such as SiC or TiC have been proposed. Amongst the metals only tungsten or gold are sufficiently less permeable than steel to warrant investigation as candidate materials for permeation barriers. It is of course possible to grow oxide layers on steel directly by heating in the atmosphere or under a variety of conditions (first route above). The direct oxidizing is normally done in an environment of open-quotes wet hydrogenclose quotes to promote the growth of chromia on, for example, nickel steels or ternary oxides on 316L to prevent corrosion. The application of surface layers (second route above), offers a greater range of materials for the formation of permeation barriers. In addition to reducing permeation, such layers should be adhesive, resistant to attack by corrosive breeder materials and should not crack during thermal cycling

  11. Evolutionary robotics

    Indian Academy of Sciences (India)

    In evolutionary robotics, a suitable robot control system is developed automatically through evolution due to the interactions between the robot and its environment. It is a complicated task, as the robot and the environment constitute a highly dynamical system. Several methods have been tried by various investigators to ...

  12. Permeation barrier for lightweight liquid hydrogen tanks

    Energy Technology Data Exchange (ETDEWEB)

    Schultheiss, D.

    2007-04-16

    For the future usage of hydrogen as an automotive fuel, its on-board storage is crucial. One approach is the storage of liquid hydrogen (LH2, 20 K) in double-walled, vacuum insulated tanks. The introduction of carbon fiber reinforced plastics (CFRP) as structural material enables a high potential of reducing the weight in comparison to the state-of-the-art stainless steel tanks. The generally high permeability of hydrogen through plastics, however, can lead to long-term degradation of the insulating vacuum. The derived objective of this dissertation was to find and apply an adequate permeation barrier (liner) on CFRP. The investigated liners were either foils adhered on CFRP specimens or coatings deposited on CFRP specimens. The coatings were produced by means of thermal spraying, metal plating or physical vapor deposition (PVD). The materials of the liners included Al, Au, Cu, Ni and Sn as well as stainless steel and diamond-like carbon. The produced liners were tested for their permeation behavior, thermal shock resistance and adherence to the CFRP substrate. Additionally, SEM micrographs were used to characterize and qualify the liners. The foils, although being a good permeation barrier, adhered weakly to the substrate. Furthermore, leak-free joining of foil segments is a challenge still to be solved. The metal plating liners exhibited the best properties. For instance, no permeation could be detected through a 50 {mu}m thick Cu coating within the accuracy of the measuring apparatus. This corresponds to a reduction of the permeation gas flow by more than factor 7400 compared to uncoated CFRP. In addition, the metal platings revealed a high adherence and thermal shock resistance. The coatings produced by means of thermal spraying and PVD did not show a sufficient permeation barrier effect. After having investigated the specimens, a 170 liter CFRP tank was fully coated with 50 {mu}m Cu by means of metal plating. (orig.)

  13. Evolutionary mysteries in meiosis.

    Science.gov (United States)

    Lenormand, Thomas; Engelstädter, Jan; Johnston, Susan E; Wijnker, Erik; Haag, Christoph R

    2016-10-19

    Meiosis is a key event of sexual life cycles in eukaryotes. Its mechanistic details have been uncovered in several model organisms, and most of its essential features have received various and often contradictory evolutionary interpretations. In this perspective, we present an overview of these often 'weird' features. We discuss the origin of meiosis (origin of ploidy reduction and recombination, two-step meiosis), its secondary modifications (in polyploids or asexuals, inverted meiosis), its importance in punctuating life cycles (meiotic arrests, epigenetic resetting, meiotic asymmetry, meiotic fairness) and features associated with recombination (disjunction constraints, heterochiasmy, crossover interference and hotspots). We present the various evolutionary scenarios and selective pressures that have been proposed to account for these features, and we highlight that their evolutionary significance often remains largely mysterious. Resolving these mysteries will likely provide decisive steps towards understanding why sex and recombination are found in the majority of eukaryotes.This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'. © 2016 The Author(s).

  14. Permeation of Comite through protective gloves.

    Science.gov (United States)

    Zainal, Hanaa; Que Hee, Shane S

    2006-09-01

    The goal of the study was to assess how protective disposable (Safeskin) and chemical protective (Sol-Vex) nitrile gloves were against Comite emulsifiable concentrate formulation containing propargite (PROP) as active pesticidal ingredient, because there were no explicit recommendations for the gloves that should be worn for hand protection. The glove material was exposed in ASTM-type I-PTC-600 permeation cells at 30.0+/-0.5 degrees C, and gas chromatography-mass spectrometry used for PROP analysis. Aqueous solutions of Comite at 40.4 mg/mL permeated both Safeskin and Sol-Vex nitrile by 8h. Safeskin showed a mean PROP mass permeated of 176+/-27 microg after 8h compared with a mean mass permeated for Sol-Vex of 3.17+/-4.08 microg. Thus, Sol-Vex was about 56 times more protective than Safeskin for an 8-h exposure. However, the kinetics of the permeation revealed that Safeskin can be worn for at least 200 min before disposal. When undiluted Comite challenged both types of nitrile, much faster permeation was observed. Safeskin gloves showed two steady state periods. The first had lag times (t(l)) values of about 1h, although normalized breakthrough times (t(b)) were gloves exposed continuously to undiluted Comite permeated above the normalized breakthrough threshold beyond 2.7h. A risk assessment revealed that the PROP skin permeation rate of 7.1 ng cm(-2)h(-1) was much slower than the first steady state Safeskin glove P(s) of 62,000 ng cm(-2)h(-1). Infrared analysis showed that the glove surfaces were not degraded by the Comite challenge. The chemically protective Sol-Vex gloves protected adequately against undiluted formulation for about 2.7h, whereas they provided protection for nearly 8h when the formulation was diluted with water to the highest concentration for field application. In contrast, the disposable Safeskin gloves did not protect at all for the undiluted formulation, but did for 200 min when the formulation was diluted with water to the highest

  15. In-site coatings to reduce H and Tr permeation

    International Nuclear Information System (INIS)

    Stoever, D.; Buchkremer, H.P.; Hecker, R.; Jonas, H.; Schaefer, J.; Zink, U.; Forsyth, N.; Thiele, W.

    1982-01-01

    The main goal of this project is the development of protective coatings to reduce or prevent Tr and H permeation through the heat exchanger walls of HTR components. The tasks of the project are: Measurement of the permeation inhibition efficiency of oxidic coatings on the high-temperature- resistant heat exchanger walls; establishing the parameters influencing permeation by variation of the process gas and steam parameters, temperature and mechanical stress; characterisation of coatings and correlation of coating characteristics with permeation measurements; investigation of permeation and corrosion mechanisms; quantitative description of H and Tr permeation by means of mathematical/physical models. (orig./IHOE) [de

  16. Evolutionary institutionalism.

    Science.gov (United States)

    Fürstenberg, Dr Kai

    Institutions are hard to define and hard to study. Long prominent in political science have been two theories: Rational Choice Institutionalism (RCI) and Historical Institutionalism (HI). Arising from the life sciences is now a third: Evolutionary Institutionalism (EI). Comparative strengths and weaknesses of these three theories warrant review, and the value-to-be-added by expanding the third beyond Darwinian evolutionary theory deserves consideration. Should evolutionary institutionalism expand to accommodate new understanding in ecology, such as might apply to the emergence of stability, and in genetics, such as might apply to political behavior? Core arguments are reviewed for each theory with more detailed exposition of the third, EI. Particular attention is paid to EI's gene-institution analogy; to variation, selection, and retention of institutional traits; to endogeneity and exogeneity; to agency and structure; and to ecosystem effects, institutional stability, and empirical limitations in behavioral genetics. RCI, HI, and EI are distinct but complementary. Institutional change, while amenable to rational-choice analysis and, retrospectively, to criticaljuncture and path-dependency analysis, is also, and importantly, ecological. Stability, like change, is an emergent property of institutions, which tend to stabilize after change in a manner analogous to allopatric speciation. EI is more than metaphorically biological in that institutional behaviors are driven by human behaviors whose evolution long preceded the appearance of institutions themselves.

  17. LIBRETTO-3: modelling tritium extraction/permeation and evaluation of permeation barriers under irradiation

    International Nuclear Information System (INIS)

    Sedano, L.A.; Fuetterer, M.A.; Viola, R.; Dies, X.

    1996-01-01

    Permeation barriers are required in order to limit the size and cost of the detritiation plants for future fusion reactor blankets of the water-cooled Pb-17Li type. The LIBRETTO irradiations were performed to evaluate the efficiency of permeation barriers under high flux reactor (HFR) conditions. Tritium extraction and permeation characteristics from Pb-17Li under variable temperatures 553-723 K, H 2 doping (0-1 vol%) and purge gas flow rates 20-100 scc/min were tested in LIBRETTO-3. An external TiC coating, an internal (TiC+Al 2 O 3 ), both produced by chemical vapour deposition (CVD), and an internal Al 2 O 3 produced by pack cementation (PC) on AISI 316L steel were tested as permeation barriers. The release mechanisms, experimental uncertainties and method for permeation barriers qualification are presented. As a result permeation reduction factors (PRF) at 0.1 dpa of 17 and 34 were obtained for the CVD-Al 2 O 3 at 498 K and for the PC-Al 2 O 3 at 508 K, respectively. These values were confirmed by a residence time analysis and are higher than in a preliminary analysis. (orig.)

  18. Effect of Permeation Enhancers on the Release Behavior and ...

    African Journals Online (AJOL)

    Purpose: The aim of this research work was to formulate, characterize and evaluate the in vitro permeation behavior of tramadol lotion containing propylene glycol (PG) and polyethylene glycol (PEG) as permeation enhancers. Methods: The permeation experiments were conducted in vitro using full thickness rabbit skin in ...

  19. Spore: Spawning Evolutionary Misconceptions?

    Science.gov (United States)

    Bean, Thomas E.; Sinatra, Gale M.; Schrader, P. G.

    2010-10-01

    The use of computer simulations as educational tools may afford the means to develop understanding of evolution as a natural, emergent, and decentralized process. However, special consideration of developmental constraints on learning may be necessary when using these technologies. Specifically, the essentialist (biological forms possess an immutable essence), teleological (assignment of purpose to living things and/or parts of living things that may not be purposeful), and intentionality (assumption that events are caused by an intelligent agent) biases may be reinforced through the use of computer simulations, rather than addressed with instruction. We examine the video game Spore for its depiction of evolutionary content and its potential to reinforce these cognitive biases. In particular, we discuss three pedagogical strategies to mitigate weaknesses of Spore and other computer simulations: directly targeting misconceptions through refutational approaches, targeting specific principles of scientific inquiry, and directly addressing issues related to models as cognitive tools.

  20. Fermentation of lactose to ethanol in cheese whey permeate and concentrated permeate by engineered Escherichia coli.

    Science.gov (United States)

    Pasotti, Lorenzo; Zucca, Susanna; Casanova, Michela; Micoli, Giuseppina; Cusella De Angelis, Maria Gabriella; Magni, Paolo

    2017-06-02

    Whey permeate is a lactose-rich effluent remaining after protein extraction from milk-resulting cheese whey, an abundant dairy waste. The lactose to ethanol fermentation can complete whey valorization chain by decreasing dairy waste polluting potential, due to its nutritional load, and producing a biofuel from renewable source at the same time. Wild type and engineered microorganisms have been proposed as fermentation biocatalysts. However, they present different drawbacks (e.g., nutritional supplements requirement, high transcriptional demand of recombinant genes, precise oxygen level, and substrate inhibition) which limit the industrial attractiveness of such conversion process. In this work, we aim to engineer a new bacterial biocatalyst, specific for dairy waste fermentation. We metabolically engineered eight Escherichia coli strains via a new expression plasmid with the pyruvate-to-ethanol conversion genes, and we carried out the selection of the best strain among the candidates, in terms of growth in permeate, lactose consumption and ethanol formation. We finally showed that the selected engineered microbe (W strain) is able to efficiently ferment permeate and concentrated permeate, without nutritional supplements, in pH-controlled bioreactor. In the conditions tested in this work, the selected biocatalyst could complete the fermentation of permeate and concentrated permeate in about 50 and 85 h on average, producing up to 17 and 40 g/l of ethanol, respectively. To our knowledge, this is the first report showing efficient ethanol production from the lactose contained in whey permeate with engineered E. coli. The selected strain is amenable to further metabolic optimization and represents an advance towards efficient biofuel production from industrial waste stream.

  1. Improved permeation barriers for tritiated waste packaging

    International Nuclear Information System (INIS)

    Vassallo, G.; Van Den Bergh, R.; Forcey, K.S.; Perujo, A.

    1994-01-01

    High-density polyethylene (HDPE) is extensively used as flexible bagging or packaging for soft tritiated waste in the tritium community because of its low permeability to the more radiotoxic form of tritium, i.e., tritiated water (HTO). However, HDPE does not represent a perfect barrier to HTO nor does it effectively hinder the permeation of elemental tritium, i.e, HT. This latter drawback is particularly important considering that the elemental form may readily convert to HTO outside of the waste package. The possible use of a multilayer film as packing material for the conditioning of tritiated waste is assessed, and its capability to hinder the permeation of elemental tritium is measured and compared with that of bare HDPE. The material investigated is readily available from the food industry. 5 refs., 1 tab

  2. Modeling and experiments on tritium permeation in fusion reactor blankets

    Science.gov (United States)

    Holland, D. F.; Longhurst, G. R.

    The determination of tritium loss from helium-cooled fusion breeding blankets are discussed. The issues are: (1) applicability of present models to permeation at low tritium pressures; (2) effectiveness of oxide layers in reducing permeation; (3) effectiveness of hydrogen addition as a means to lower tritium permeation; and (4) effectiveness of conversion to tritiated water and subsequent trapping to reduce permeation. Theoretical models applicable to these issues are discussed, and results of experiments in two areas are presented; permeation of mixtures of hydrogen isotopes and conversion to tritiated water.

  3. Modeling and experiments on tritium permeation in fusion reactor blankets

    International Nuclear Information System (INIS)

    Holland, D.F.; Longhurst, G.R.

    1985-01-01

    Issues are discussed that are critical in determining tritium loss from helium-cooled fusion breeding blankets. These issues are: (a) applicability of present models to permeation at low tritium pressures, (b) effectiveness of oxide layers in reducing permeation, (c) effectiveness of hydrogen addition as a means to lower tritium permeation, and (d) effectiveness of conversion to tritiated water and subsequent trapping as a means to reduce permeation. The paper discusses theoretical models applicable to these issues, and presents results of experiments in two areas: permeation of mixtures of hydrogen isotopes and conversion to tritiated water

  4. Enzymatic hydrolysis of lactose of whey permeate

    Directory of Open Access Journals (Sweden)

    Karina Nascimento de Almeida

    2015-09-01

    Full Text Available The whey permeate is the residual of the concentration process of the whey proteins by ultrafiltration method. It contains important nutrients such as lactose, minerals and some proteins and lipids. It is without an ending industrial waste that causes serious damage to the environment. For its full use the lactose must be hydrolyzed to enable its consumption by intolerant people. The enzymatic hydrolysis by lactase (β-galactosidase of Kluyveromyces lactis yeast is a safe method that does not compromise the integrity of other nutrients, enabling further use of the permeate as a raw material. This study aimed to perform tests of enzymatic hydrolysis of lactose in whey permeate formulations in a concentration of 0.2%, 0.7% and 1% at 30, 60 and 90 minutes with pH 6.3 medium and 37 °C. The reactions were monitored by high performance liquid chromatography which showed that the enzyme concentration of 0.7% at time 30 minutes formulations became safe for consumption by lactose intolerant people, according to minimum levels established by law.

  5. Flibe-D2 Permeation Experiment and Analysis

    International Nuclear Information System (INIS)

    Fukada, S.; Anderl, R.A.; Pawelko, R.J.; Smolik, G.R.; Schuetz, S.T.; O'Brien, J.E.; Nishimura, H.; Hatano, Y.; Terai, T.; Petti, D.A.; Sze, D.-K.; Tanaka, S.

    2003-01-01

    Experiment of D 2 permeation through Ni facing with purified Flibe is being carried out under the Japan-US joint research project (JUPITER-II). The experiment is proceeding in the following phases; (i) fabrication and assembly of a dual-probe permeation apparatus, (ii) a single-probe Ni/D 2 permeation experiment without Flibe, (iii) a dual-probe Ni/D 2 permeation experiment without Flibe, (iv) Flibe chemical purification by HF/H 2 gas bubbling, (v) physical purification by Flibe transport through a porous Ni filter, (vi) Ni/Flibe/D 2 permeation experiment, and (vii) Ni/Flibe/HT permeation experiment. The present paper describes results of the single and dual Ni/D 2 permeation experiments in detail

  6. Microstructural Study on Oxygen Permeated Arc Beads

    Directory of Open Access Journals (Sweden)

    Kuan-Heng Liu

    2015-01-01

    Full Text Available We simulated short circuit of loaded copper wire at ambient atmosphere and successfully identified various phases of the arc bead. A cuprous oxide flake was formed on the surface of the arc bead in the rapid solidification process, and there were two microstructural constituents, namely, Cu-κ eutectic structure and solutal dendrites. Due to the arc bead formed at atmosphere during the local equilibrium solidification process, the phase of arc bead has segregated to the cuprous oxide flake, Cu-κ eutectic, and Cu phase solutal dendrites, which are the fingerprints of the arc bead permeated by oxygen.

  7. Hydrogen isotope permeation in elastomeric materials

    International Nuclear Information System (INIS)

    Steinmeyer, R.H.; Braun, J.D.

    1976-01-01

    The permeabilities of elastomeric and polymeric materials to hydrogen isotopes were measured at room temperature. The technique for measuring permeation rates is based on the following constant-volume method: a fixed pressure of gas is applied to one side of the specimen to be studied and the permeability constant is determined from the observed rate of pressure increase in an initially evacuated volume on the other side of the specimen. Permeability constants for hydrogen, deuterium, and tritium were measured for Mylar, Teflon, Kapton, Saran, Buna-N, and latex rubber. Results were compared with literature values for hydrogen and deuterium where available and showed excellent agreement

  8. Organic fluid permeation through fluoropolymer membranes

    Science.gov (United States)

    Nemser, Stuart M.; Kosaraju, Praveen; Bowser, John

    2015-07-14

    Separation of the components of liquid mixtures is achieved by contacting a liquid mixture with a nonporous membrane having a fluoropolymer selectively permeable layer and imposing a pressure gradient across the membrane from feed side to permeate side. Unusually high transmembrane flux is obtained when the membrane is subjected to one or more process conditions prior to separation. These include (a) leaving some residual amount of membrane casting solvent in the membrane, and (b) contacting the membrane with a component of the mixture to be separated for a duration effective to saturate the membrane with the component.

  9. Tritium permeation losses in HYLIFE-II heat exchanger tubes

    International Nuclear Information System (INIS)

    Longhurst, G.R.; Dolan, T.J.

    1990-01-01

    Tritium permeation through the intermediate heat exchanger of the HYLIFE-II inertial fusion design concept is evaluated for routine operating conditions. The permeation process is modelled using the Lewis analogy combined with surface recombination. It is demonstrated that at very low driving potentials, permeation becomes proportional to the first power of the driving potential. The model predicts that under anticipated conditions the primary cooling loop will pass about 6% of the tritium entering it to the intermediate coolant. Possible approached to reducing tritium permeation are explored. Permeation is limited by turbulent diffusion transport through the molten salt. Hence, surface barriers with impendance factors typical of present technology can do very little to reduce permeation. Low Flibe viscosity is desirable. An efficient tritium removal system operating on the Flibe before it gets to the intermediate heat exchanger is required. Needs for further research are highlighted. 9 refs., 2 figs., 1 tab

  10. Solar constraints

    International Nuclear Information System (INIS)

    Provost, J.

    1984-01-01

    Accurate tests of the theory of stellar structure and evolution are available from the Sun's observations. The solar constraints are reviewed, with a special attention to the recent progress in observing global solar oscillations. Each constraint is sensitive to a given region of the Sun. The present solar models (standard, low Z, mixed) are discussed with respect to neutrino flux, low and high degree five-minute oscillations and low degree internal gravity modes. It appears that actually there do not exist solar models able to fully account for all the observed quantities. (Auth.)

  11. Development of a Contact Permeation Test Fixture and Method

    Science.gov (United States)

    2013-04-01

    Permeation and Analytical Solutions Team Quality System documentation and the guidance found in the ISO 17025 standard. All permeation and...annular ring (left) and no pressure (right). 2.2.4 Quality Controls Analytical permeation testing was conducted in accordance with ISO 17025 quality...internal standard. This mixture was vortexed for 20–30 s then centrifuged at 15,000 rpm for 5 min in a Micromax microcentrifuge (Thermo IEC ; Needham

  12. In situ measurement of tritium permeation through stainless steel

    Science.gov (United States)

    Luscher, Walter G.; Senor, David J.; Clayton, Kevin K.; Longhurst, Glen R.

    2013-06-01

    The TMIST-2 irradiation experiment was conducted in the Advanced Test Reactor at Idaho National Laboratory to evaluate tritium permeation through Type 316 stainless steel (316 SS). The interior of a 316 SS seamless tube specimen was exposed to a 4He carrier gas mixed with a specified quantity of tritium (T2) to yield partial pressures of 0.1, 5, and 50 Pa at 292 °C and 330 °C. In situ tritium permeation measurements were made by passing a He-Ne sweep gas over the outer surface of the specimen to carry the permeated tritium to a bubbler column for liquid scintillation counting. Results from in situ permeation measurements were compared with predictions based on an ex-reactor permeation correlation in the literature. In situ permeation data were also used to derive an in-reactor permeation correlation as a function of temperature and pressure over the ranges considered in this study. In addition, the triton recoil contribution to tritium permeation, which results from the transmutation of 3He to T, was also evaluated by introducing a 4He carrier gas mixed with 3He at a partial pressure of 1013 Pa at 330 °C. Less than 3% of the tritium resulting from 3He transmutation contributed to tritium permeation.

  13. Separation of aromatics by vapor permeation through solvent swollen membrane

    Energy Technology Data Exchange (ETDEWEB)

    Ito, A.; Adachi, K.; Feng, Y. [Niigata University, Niigata (Japan)

    1995-12-20

    A vapor permeation process for aromatics separation from a hydrocarbon mixture was studied by means of the simultaneous permeation of dimethylsulfoxide vapor as an agent for membrane swelling and preferential permeation of aromatics. The separation performance of the process was demonstrated by a polyvinylalcohol membrane for mixed vapors of benzene/cyclohexane, xylene/octane and a model gasoline. The aromatic vapors preferentially permeated from these mixed vapor feeds. The separation factor was over 10. The separation mechanism of the process mainly depends on the relative salability of the vapors between aromatics and other hydrocarbons in dimethylsulfoxide. 14 refs., 9 figs., 1 tab.

  14. Hydrogen permeation resistant layers for liquid metal reactors

    International Nuclear Information System (INIS)

    McGuire, J.C.

    1980-03-01

    Reviewing the literature in the tritium diffusion field one can readily see a wide divergence in results for both the response of permeation rate to pressure, and the effect of oxide layers on total permeation rates. The basic mechanism of protective oxide layers is discussed. Two coatings which are less hydrogen permeable than the best naturally occurring oxide are described. The work described is part of an HEDL-ANL cooperative research program on Tritium Permeation in Liquid Metal Cooled Reactors. This includes permeation work on hydrogen, deuterium, and tritium with the hydrogen-deuterium research leading to the developments presented

  15. In situ measurement of tritium permeation through stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Luscher, Walter G., E-mail: walter.luscher@pnnl.gov [Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, WA 99352 (United States); Senor, David J., E-mail: david.senor@pnnl.gov [Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, WA 99352 (United States); Clayton, Kevin K., E-mail: kevin.clayton@inl.gov [Idaho National Laboratory, 2525 Fremont Ave., Idaho Falls, ID 83415 (United States); Longhurst, Glen R., E-mail: glenlonghurst@suu.edu [Idaho National Laboratory, 2525 Fremont Ave., Idaho Falls, ID 83415 (United States)

    2013-06-15

    Highlights: ► In situ tritium permeation measurements collected over broad pressure range. ► Test conditions relevant to 316 SS in commercial light water reactors. ► Comparisons between in- and ex-reactor measurements provided. ► Correlation between tritium permeation, temperature, and pressure developed. -- Abstract: The TMIST-2 irradiation experiment was conducted in the Advanced Test Reactor at Idaho National Laboratory to evaluate tritium permeation through Type 316 stainless steel (316 SS). The interior of a 316 SS seamless tube specimen was exposed to a {sup 4}He carrier gas mixed with a specified quantity of tritium (T{sub 2}) to yield partial pressures of 0.1, 5, and 50 Pa at 292 °C and 330 °C. In situ tritium permeation measurements were made by passing a He–Ne sweep gas over the outer surface of the specimen to carry the permeated tritium to a bubbler column for liquid scintillation counting. Results from in situ permeation measurements were compared with predictions based on an ex-reactor permeation correlation in the literature. In situ permeation data were also used to derive an in-reactor permeation correlation as a function of temperature and pressure over the ranges considered in this study. In addition, the triton recoil contribution to tritium permeation, which results from the transmutation of {sup 3}He to T, was also evaluated by introducing a {sup 4}He carrier gas mixed with {sup 3}He at a partial pressure of 1013 Pa at 330 °C. Less than 3% of the tritium resulting from {sup 3}He transmutation contributed to tritium permeation.

  16. The constraints

    International Nuclear Information System (INIS)

    Jones, P.M.S.

    1987-01-01

    There are considerable incentives for the use of nuclear in preference to other sources for base load electricity generation in most of the developed world. These are economic, strategic, environmental and climatic. However, there are two potential constraints which could hinder the development of nuclear power to its full economic potential. These are public opinion and financial regulations which distort the nuclear economic advantage. The concerns of the anti-nuclear lobby are over safety, (especially following the Chernobyl accident), the management of radioactive waste, the potential effects of large scale exposure of the population to radiation and weapons proliferation. These are discussed. The financial constraint is over two factors, the availability of funds and the perception of cost, both of which are discussed. (U.K.)

  17. Permeation of Light Gases through Hexagonal Ice

    Directory of Open Access Journals (Sweden)

    Luis Gales

    2012-09-01

    Full Text Available Gas separation using porous solids have attracted great attention due to their energetic applications. There is an enormous economic and environmental interest in the development of improved technologies for relevant processes, such as H2 production, CO2 separation or O2 and N2 purification from air. New materials are needed for achieving major improvements. Crystalline materials, displaying unidirectional and single-sized pores, preferentially with low pore tortuosity and high pore density, are promising candidates for membrane synthesis. Herein, we study hexagonal ice crystals as an example of this class of materials. By slowly growing ice crystals inside capillary tubes we were able to measure the permeation of several gas species through ice crystals and investigate its relation with both the size of the guest molecules and temperature of the crystal.

  18. Electrical insulator assembly with oxygen permeation barrier

    Science.gov (United States)

    Van Der Beck, Roland R.; Bond, James A.

    1994-01-01

    A high-voltage electrical insulator (21) for electrically insulating a thermoelectric module (17) in a spacecraft from a niobium-1% zirconium alloy wall (11) of a heat exchanger (13) filled with liquid lithium (16) while providing good thermal conductivity between the heat exchanger and the thermoelectric module. The insulator (21) has a single crystal alumina layer (SxAl.sub.2 O.sub.3, sapphire) with a niobium foil layer (32) bonded thereto on the surface of the alumina crystal (26) facing the heat exchanger wall (11), and a molybdenum layer (31) bonded to the niobium layer (32) to act as an oxygen permeation barrier to preclude the oxygen depleting effects of the lithium from causing undesirable niobium-aluminum intermetallic layers near the alumina-niobium interface.

  19. Tritium permeation model for plasma facing components

    Science.gov (United States)

    Longhurst, G. R.

    1992-12-01

    This report documents the development of a simplified one-dimensional tritium permeation and retention model. The model makes use of the same physical mechanisms as more sophisticated, time-transient codes such as implantation, recombination, diffusion, trapping and thermal gradient effects. It takes advantage of a number of simplifications and approximations to solve the steady-state problem and then provides interpolating functions to make estimates of intermediate states based on the steady-state solution. The model is developed for solution using commercial spread-sheet software such as Lotus 123. Comparison calculations are provided with the verified and validated TMAP4 transient code with good agreement. Results of calculations for the ITER CDA diverter are also included.

  20. Tritium permeation model for plasma facing components

    International Nuclear Information System (INIS)

    Longhurst, G.R.

    1992-12-01

    This report documents the development of a simplified one-dimensional tritium permeation and retention model. The model makes use of the same physical mechanisms as more sophisticated, time-transient codes such as implantation, recombination, diffusion, trapping and thermal gradient effects. It takes advantage of a number of simplifications and approximations to solve the steady-state problem and then provides interpolating functions to make estimates of intermediate states based on the steady-state solution. The model is developed for solution using commercial spread-sheet software such as Lotus 123. Comparison calculations are provided with the verified and validated TMAP4 transient code with good agreement. Results of calculations for the ITER CDA diverter are also included

  1. Permeation of Telone EC through protective gloves.

    Science.gov (United States)

    Zainal, Hanaa; Que Hee, Shane S

    2005-09-30

    Telone is a potent fumigant that is based on the chlorinated unsaturated hydrocarbon, 1,3-dichloropropene (1,3-DCP). It is often applied without dilution and so poses severe inhalation and air pollution threats. Urinary metabolites of 1,3-DCP have been detected after Telone skin exposure, so that preventing dermal exposure is also important. The objective of the study was to assess if nitrile and multi-layer ("laminated") gloves provide adequate protection against Telone EC formulation. To accomplish this, disposable (Safeskin) and chemically resistant (Sol-Vex) nitrile and laminated (Barrier mark and Silver Shield) glove materials were challenged by Telone EC with hexane liquid collection in an ASTM-type I-PTC-600 permeation cell. Analyses of cis- and trans-1,3-DCP in the collection fluid at specified times were performed on a moderately polar capillary column by gas chromatography-electron capture detection. Telone EC caused microholes in both nitrile materials, though the chemically protective material was degraded slower than the disposable nitrile. The laminated gloves offered limited protection. Silver Shield protected best because 1.5-2.3 mg 1,3-DCP permeated by 8 h relative to 2.5-7.6 mg for Barrier, implying about 2.5 times more protection for 8 h. Even for Silver Shield, the extent of protection was inadequate as illustrated by a risk assessment of the skin exposure situation. The normalized breakthrough times for both types of laminated gloves varied between 27 and 60 min. It is recommended that Viton gloves still be worn for protection.

  2. A study on reverse osmosis permeating treatment for yarn dyeing ...

    African Journals Online (AJOL)

    This paper presents a fuzzy linear regression model for estimation of reverse osmosis permeating parameters conditions. The proposed model can effectively take on non-crisp, fuzzy and crisp data. This study model used for estimation of reverse osmosis permeating parameters data from Tirupur examines the variables that ...

  3. Effect of Nutrient Formulations on Permeation of Proteins and Lipids ...

    African Journals Online (AJOL)

    Purpose: To investigate the effect of nutrient formulations on the permeation of proteins and lipids through porcine intestine in vitro. Method: In vitro permeation studies of proteins and lipids of two peptide-based formulations, composed of various compounds and sources of hydrolyzed protein was carried out, and compared ...

  4. An unheated permeation device for calibrating atmospheric VOC measurements

    Directory of Open Access Journals (Sweden)

    J. Brito

    2011-10-01

    Full Text Available The development of an unpowered permeation device for continuous calibration of in-situ instruments measuring atmospheric volatile organic compounds (VOCs is described. Being lightweight and compact, and containing only negligible amounts of chemicals, the device is especially suited for field use such as on board aircraft. Its speciality is to maintain the permeation process in thermal equilibrium, so that the instantaneous permeation rate can be ascribed to a simple temperature measurement. This equilibrium state is maintained by a combination of three features: (i a thin PTFE membrane as permeation medium which guarantees short stabilization times, (ii a water bath as heat buffer, and (iii a vacuum-panel based insulation, in which features (ii and (iii minimize temperature drifts to ~30 mK h−1 per Kelvin temperature difference to the environment. The respective uncertainty of the permeation rate due to thermal non-equilibrium is kept below 1%. An extensive theory part details the major permeation processes of gases through porous polymers, being Fick's diffusion, Knudsen flow, and viscous flow. Both the measured stabilization time and the measured temperature dependence of the permeation rate independently indicate that the permeation can be described by a viscous flow model, where diffusion of the gas molecules in large pores (having a diameter of >0.05 μm dominates.

  5. Implantation driven permeation behavior of deuterium through pure tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Hirofumi E-mail: nakamura@tpl.tokai.jaeri.go.jp; Hayashi, Takumi; Nishi, Masataka; Arita, Makoto; Okuno, Kenji

    2001-09-01

    Implantation driven permeation behavior of deuterium through pure tungsten has been investigated to estimate the amount of tritium permeation through its barrier in a thermo-nuclear fusion device. The permeation experiments were performed on pure tungsten foil of 25 {mu}m thickness under conditions of incident flux of 1.9x10{sup 18}-1.1x10{sup 19} D{sup +}/m{sup 2}s, incident ion energy of 200-2000 eV, and specimen temperature of 512-660 K. As a result of this steady-state permeation experiment, the rate-determining process of deuterium permeation was found to be controlled by diffusion at both implanted and permeated sides. On the other hand, transient permeation was strongly affected by trap effect in the specimen. Simulation analysis using TMAP code on transient permeation behavior indicates the existence of a trap site with a trap energy of nearly 1eV and with a trap density of over several ten's ppm in tungsten.

  6. Implantation driven permeation behavior of deuterium through pure tungsten

    International Nuclear Information System (INIS)

    Nakamura, Hirofumi; Hayashi, Takumi; Nishi, Masataka; Arita, Makoto; Okuno, Kenji

    2001-01-01

    Implantation driven permeation behavior of deuterium through pure tungsten has been investigated to estimate the amount of tritium permeation through its barrier in a thermo-nuclear fusion device. The permeation experiments were performed on pure tungsten foil of 25 μm thickness under conditions of incident flux of 1.9x10 18 -1.1x10 19 D + /m 2 s, incident ion energy of 200-2000 eV, and specimen temperature of 512-660 K. As a result of this steady-state permeation experiment, the rate-determining process of deuterium permeation was found to be controlled by diffusion at both implanted and permeated sides. On the other hand, transient permeation was strongly affected by trap effect in the specimen. Simulation analysis using TMAP code on transient permeation behavior indicates the existence of a trap site with a trap energy of nearly 1eV and with a trap density of over several ten's ppm in tungsten

  7. Questioning Clerkship: Applying Popper's Evolutionary Analysis of Learning to Medical Student Training

    Science.gov (United States)

    Chitpin, Jeremy Sebastian; Chitpin, Stephanie

    2017-01-01

    Purpose: Through a series of critical discussions on Karl Popper's evolutionary analysis of learning and the non-authoritarian values it promotes, the purpose of this paper is to advocate a Popperian approach for building medical student knowledge. Specifically, it challenges positivist assumptions that permeate the design and management of many…

  8. Permeation of aromatic solvent mixtures through nitrile protective gloves.

    Science.gov (United States)

    Chao, Keh-Ping; Hsu, Ya-Ping; Chen, Su-Yi

    2008-05-30

    The permeation of binary and ternary mixtures of benzene, toluene, ethyl benzene and p-xylene through nitrile gloves were investigated using the ASTM F739 test cell. The more slowly permeating component of a mixture was accelerated to have a shorter breakthrough time than its pure form. The larger differences in solubility parameter between a solvent mixture and glove resulted in a lower permeation rate. Solubility parameter theory provides a potential approach to interpret the changes of permeation properties for BTEX mixtures through nitrile gloves. Using a one-dimensional diffusion model based on Fick's law, the permeation concentrations of ASTM F739 experiments were appropriately simulated by the estimated diffusion coefficient and solubility. This study will be a fundamental work for the risk assessment of the potential dermal exposure of workers wearing protective gloves.

  9. Brincadeiras de faz-de-conta em crianças autistas: limites e possibilidades numa perspectiva evolucionista Make-Believe play in autistic children: constraints and possibilities in the evolutionary perspective

    Directory of Open Access Journals (Sweden)

    Carla Silva Fiaes

    2009-12-01

    Full Text Available A constatação da presença universal da brincadeira na infância sugere que tal comportamento deva ter grande valor adaptativo para a espécie. Apesar de universal, a brincadeira sofre interferência do estado desenvolvimental do indivíduo. Crianças com autismo, por exemplo, apresentam dificuldades no brincar, o que nos leva a questionamentos sobre a natureza da sua brincadeira simbólica, se todo faz-de-conta necessariamente inclui teoria da mente e porque um fenômeno considerado universal surge de modo tão atípico no autismo. O artigo discute essas questões à luz da psicologia evolucionista, ilustrando relatos de brincadeiras espontâneas de crianças autistas coletados em instituições educacionais na cidade de Salvador (BA. Os resultados sugerem que os episódios de faz-de-conta envolvem freqüentemente a presença de objetos como apoio para o desenvolvimento da brincadeira. Tal fato está em acordo com a descrição de alguns autores sobre o desenvolvimento do faz-de-conta, com seu início mais sustentado por objetos e independente de metarepresentação.The universal presence of play into the infancy suggests that this behavior must to have a great value adaptative to specie. Although universal, the play receive interference of developmental degree, as children with autism. The difficulties presented by autistic children on the play have came questions about the nature of symbolic play, if all make-believe include theory of mind and why a phenomenon universal emerge of differentiated way in the autism. The article discuss this questions to view of evolutionary psychology, illustrating relates of autistic children's spontaneous play collecting in educational institutions in the Salvador's City. The results suggests that the make believe episodes involves the presence of objects as supportive to developmental of the play. This fact is in accord with the description of some authors about the make-believe developmental, with the

  10. Attractive evolutionary equilibria

    NARCIS (Netherlands)

    Joosten, Reinoud A.M.G.; Roorda, Berend

    2011-01-01

    We present attractiveness, a refinement criterion for evolutionary equilibria. Equilibria surviving this criterion are robust to small perturbations of the underlying payoff system or the dynamics at hand. Furthermore, certain attractive equilibria are equivalent to others for certain evolutionary

  11. Evolutionary Stable Strategy

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 21; Issue 9. Evolutionary Stable Strategy: Application of Nash Equilibrium in Biology. General Article Volume 21 Issue 9 September 2016 pp 803- ... Keywords. Evolutionary game theory, evolutionary stable state, conflict, cooperation, biological games.

  12. Developmental constraints on behavioural flexibility.

    Science.gov (United States)

    Holekamp, Kay E; Swanson, Eli M; Van Meter, Page E

    2013-05-19

    We suggest that variation in mammalian behavioural flexibility not accounted for by current socioecological models may be explained in part by developmental constraints. From our own work, we provide examples of constraints affecting variation in behavioural flexibility, not only among individuals, but also among species and higher taxonomic units. We first implicate organizational maternal effects of androgens in shaping individual differences in aggressive behaviour emitted by female spotted hyaenas throughout the lifespan. We then compare carnivores and primates with respect to their locomotor and craniofacial adaptations. We inquire whether antagonistic selection pressures on the skull might impose differential functional constraints on evolvability of skulls and brains in these two orders, thus ultimately affecting behavioural flexibility in each group. We suggest that, even when carnivores and primates would theoretically benefit from the same adaptations with respect to behavioural flexibility, carnivores may nevertheless exhibit less behavioural flexibility than primates because of constraints imposed by past adaptations in the morphology of the limbs and skull. Phylogenetic analysis consistent with this idea suggests greater evolutionary lability in relative brain size within families of primates than carnivores. Thus, consideration of developmental constraints may help elucidate variation in mammalian behavioural flexibility.

  13. Development of tritium permeation barriers on Al base in Europe

    Science.gov (United States)

    Benamati, G.; Chabrol, C.; Perujo, A.; Rigal, E.; Glasbrenner, H.

    The development of the water cooled lithium lead (WCLL) DEMO fusion reactor requires the production of a material capable of acting as a tritium permeation barrier (TPB). In the DEMO blanket reactor permeation barriers on the structural material are required to reduce the tritium permeation from the Pb-17Li or the plasma into the cooling water to acceptable levels (HIP) technology and spray (this one developed also for repair) deposition techniques. The final goal is to select a reference technique to be used in the blanket of the DEMO reactor and in the ITER test module fabrication. The activities performed in four European laboratories are summarised here.

  14. Reemission and permeation of deuterium implanted into metals

    International Nuclear Information System (INIS)

    Tanabe, T.; Furuyama, Y.; Imoto, S.

    1984-01-01

    Focusing on the marked depression of deuterium permeation rate during the deuteron bombardment, implantation experiments coupled with gaseous permeation experiments are performed on pure Ni and Ni with evaporated MnO. It is concluded that the reemission of implanted deuterium is initially depressed, but it soon becomes enhanced with increase of fluence leading to a rapid decrease of permeation rate at the intermediate temperatures 600-1000 K, which is attributed to the formation of short diffusion paths from the projected range to the front surface. (orig.)

  15. Permeation enhancer strategies in transdermal drug delivery.

    Science.gov (United States)

    Marwah, Harneet; Garg, Tarun; Goyal, Amit K; Rath, Goutam

    2016-01-01

    Today, ∼74% of drugs are taken orally and are not found to be as effective as desired. To improve such characteristics, transdermal drug delivery was brought to existence. This delivery system is capable of transporting the drug or macromolecules painlessly through skin into the blood circulation at fixed rate. Topical administration of therapeutic agents offers many advantages over conventional oral and invasive techniques of drug delivery. Several important advantages of transdermal drug delivery are prevention from hepatic first pass metabolism, enhancement of therapeutic efficiency and maintenance of steady plasma level of the drug. Human skin surface, as a site of drug application for both local and systemic effects, is the most eligible candidate available. New controlled transdermal drug delivery systems (TDDS) technologies (electrically-based, structure-based and velocity-based) have been developed and commercialized for the transdermal delivery of troublesome drugs. This review article covers most of the new active transport technologies involved in enhancing the transdermal permeation via effective drug delivery system.

  16. Permeation rates for RTF metal hydride vessels

    International Nuclear Information System (INIS)

    Klein, J.E.

    1992-01-01

    Contamination rates have been estimated for the RTF nitrogen heating and cooling system (NH and CS) due to tritium permeation through the walls of metal hydride vessels. Tritium contamination of the NH and CS will be seen shortly after start-up of the RTF with the majority of it coming from the TCAP units. Contamination rates of the NH and CS are estimated to exceed 400 Ci/year after three years of operation and will elevate tritium concentrations in the NH and CS above 6 x 10 -3 μCi/cc. To reduce tritium activity in the NH and CS, a stripper or ''getter'' bed may need to be installed in the NH and CS. Increasing the purge rate of nitrogen from the NH and CS is shown to be an impractical method for reducing tritium activity due to the high purge rates required. Stripping of the NH and CS nitrogen in the glove box stripper system will give a temporary lowering of tritium activity in the NH and CS, but tritium activity will return to its previous level in approximately two weeks

  17. Constraints and spandrels of interareal connectomes

    Science.gov (United States)

    Rubinov, Mikail

    2016-12-01

    Interareal connectomes are whole-brain wiring diagrams of white-matter pathways. Recent studies have identified modules, hubs, module hierarchies and rich clubs as structural hallmarks of these wiring diagrams. An influential current theory postulates that connectome modules are adequately explained by evolutionary pressures for wiring economy, but that the other hallmarks are not explained by such pressures and are therefore less trivial. Here, we use constraint network models to test these postulates in current gold-standard vertebrate and invertebrate interareal-connectome reconstructions. We show that empirical wiring-cost constraints inadequately explain connectome module organization, and that simultaneous module and hub constraints induce the structural byproducts of hierarchies and rich clubs. These byproducts, known as spandrels in evolutionary biology, include the structural substrate of the default-mode network. Our results imply that currently standard connectome characterizations are based on circular analyses or double dipping, and we emphasize an integrative approach to future connectome analyses for avoiding such pitfalls.

  18. Evolutionary molecular medicine.

    Science.gov (United States)

    Nesse, Randolph M; Ganten, Detlev; Gregory, T Ryan; Omenn, Gilbert S

    2012-05-01

    Evolution has long provided a foundation for population genetics, but some major advances in evolutionary biology from the twentieth century that provide foundations for evolutionary medicine are only now being applied in molecular medicine. They include the need for both proximate and evolutionary explanations, kin selection, evolutionary models for cooperation, competition between alleles, co-evolution, and new strategies for tracing phylogenies and identifying signals of selection. Recent advances in genomics are transforming evolutionary biology in ways that create even more opportunities for progress at its interfaces with genetics, medicine, and public health. This article reviews 15 evolutionary principles and their applications in molecular medicine in hopes that readers will use them and related principles to speed the development of evolutionary molecular medicine.

  19. Evolutionary cell biology: two origins, one objective.

    Science.gov (United States)

    Lynch, Michael; Field, Mark C; Goodson, Holly V; Malik, Harmit S; Pereira-Leal, José B; Roos, David S; Turkewitz, Aaron P; Sazer, Shelley

    2014-12-02

    All aspects of biological diversification ultimately trace to evolutionary modifications at the cellular level. This central role of cells frames the basic questions as to how cells work and how cells come to be the way they are. Although these two lines of inquiry lie respectively within the traditional provenance of cell biology and evolutionary biology, a comprehensive synthesis of evolutionary and cell-biological thinking is lacking. We define evolutionary cell biology as the fusion of these two eponymous fields with the theoretical and quantitative branches of biochemistry, biophysics, and population genetics. The key goals are to develop a mechanistic understanding of general evolutionary processes, while specifically infusing cell biology with an evolutionary perspective. The full development of this interdisciplinary field has the potential to solve numerous problems in diverse areas of biology, including the degree to which selection, effectively neutral processes, historical contingencies, and/or constraints at the chemical and biophysical levels dictate patterns of variation for intracellular features. These problems can now be examined at both the within- and among-species levels, with single-cell methodologies even allowing quantification of variation within genotypes. Some results from this emerging field have already had a substantial impact on cell biology, and future findings will significantly influence applications in agriculture, medicine, environmental science, and synthetic biology.

  20. Evolutionary computation in zoology and ecology.

    Science.gov (United States)

    Boone, Randall B

    2017-12-01

    Evolutionary computational methods have adopted attributes of natural selection and evolution to solve problems in computer science, engineering, and other fields. The method is growing in use in zoology and ecology. Evolutionary principles may be merged with an agent-based modeling perspective to have individual animals or other agents compete. Four main categories are discussed: genetic algorithms, evolutionary programming, genetic programming, and evolutionary strategies. In evolutionary computation, a population is represented in a way that allows for an objective function to be assessed that is relevant to the problem of interest. The poorest performing members are removed from the population, and remaining members reproduce and may be mutated. The fitness of the members is again assessed, and the cycle continues until a stopping condition is met. Case studies include optimizing: egg shape given different clutch sizes, mate selection, migration of wildebeest, birds, and elk, vulture foraging behavior, algal bloom prediction, and species richness given energy constraints. Other case studies simulate the evolution of species and a means to project shifts in species ranges in response to a changing climate that includes competition and phenotypic plasticity. This introduction concludes by citing other uses of evolutionary computation and a review of the flexibility of the methods. For example, representing species' niche spaces subject to selective pressure allows studies on cladistics, the taxon cycle, neutral versus niche paradigms, fundamental versus realized niches, community structure and order of colonization, invasiveness, and responses to a changing climate.

  1. Study of tritium permeation through Peach Bottom Steam Generator tubes

    International Nuclear Information System (INIS)

    Yang, L.; Baugh, W.A.; Baldwin, N.L.

    1977-06-01

    The report describes the equipment developed, samples tested, procedures used, and results obtained in the tritium permeation tests conducted on steam generator tubing samples which were removed from the Peach Bottom Unit No. 1 reactor

  2. Recent results on implantation and permeation into fusion reactor materials

    Science.gov (United States)

    Anderl, R. A.; Holland, D. F.; Longhurst, G. R.; Struttman, D. A.

    This paper reports on implantation-driven permeation experiments that have been made for primary candidate alloy (PCA) and the ferritic steel HT-9 using deuterium ion beams from an accelerator. The results include measurements of the implantation flux and fluence dependence of the deuterium reemission and permeation for specimens heated to approximately 430(0)C. Simultaneous measurements of the ions sputtered from the specimen front surface with a secondary ion mass spectrometer provided some characterization of the surface condition throughout an experiment. For both materials, the permeation rate was lowered by the implantation process. However, the steady state permeation rate for HT-9 was found to be at least a factor of 5 greater than that for PCA.

  3. Phase Change Permeation Technology for Environmental Control & Life Support Systems

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA is evaluating Dutyion™, a phase change permeation membrane technology developed by Design Technology and Irrigation (DTI), for use in future advanced life...

  4. Effect of residual stresses on hydrogen permeation in iron

    International Nuclear Information System (INIS)

    Mouanga, M.; Bercot, P.; Takadoum, J.

    2010-01-01

    The effect of residual stresses on electrochemical permeation in iron membrane was investigated. Four thermal and mechanical treatments were chosen to obtain different surface states in relation to the residual stresses. Residual stresses were determined by X-ray diffraction (XRD) using the Macherauch and Mueller method. The results were completed by the microhardness measurements. For all iron membranes, compressive residual stresses were obtained. Electrochemical permeation experiments using a Devanathan and Stachurski cell were employed to determine the hydrogen permeation behaviour of the various iron membranes. The latter was charged with hydrogen by galvanostatic cathodic polarization in 0.1 M NaOH at 25 deg. C. The experimental results revealed that hydrogen permeation rate increases with increasing residual stresses introduced in iron membranes.

  5. A study of radon 222 permeation through plastic membranes. Application to a method of radon measurement in water and saturated soils

    International Nuclear Information System (INIS)

    Labed, V.

    1991-04-01

    In order to improve the BARASOL R device and to use it in water-saturated soils and in pressure constraint conditions, we have studied radon 222 permeation through plastic membranes. While the permeation process usually takes place between two media being in the same state, most often gaseous, the present study describes the transfer of radon 222 from the water to the air via a membrane. Polypropylene membranes have been tested with an experimental set-up by monitoring the evolution of radon concentrations in water and in air. The permeation coefficient and the activation energy were calculated in various conditions. With a second experimental set-up, we have tested the polyethylene membrane which has been adapted on the BARASOL. In these conditions, we have shown that it is possible to measure radon in water at concentrations around 10 3 Bq.m -3 [fr

  6. Measurement of tritium permeation through resistant materials near room temperature

    International Nuclear Information System (INIS)

    Maienschein, J.; DuVal, V.; McMurphy, F.; Uribe, F.; Musket, R.; Brown, D.

    1985-01-01

    To measure tritium permeation through low-permeability materials at 50 to 170 0 C, we use highly-sensitive liquid scintillation counting to detect the permeating tritium. To validate our method, we conducted extensive experiments with copper, for which much data exists for comparison. We report permeability of tritium through copper at 50, 100, and 170 0 C, and discuss details of the experimental technique. Further plans are outlined. 15 refs., 5 figs., 1 tab

  7. Human compulsivity: A perspective from evolutionary medicine.

    Science.gov (United States)

    Stein, Dan J; Hermesh, Haggai; Eilam, David; Segalas, Cosi; Zohar, Joseph; Menchon, Jose; Nesse, Randolph M

    2016-05-01

    Biological explanations address not only proximal mechanisms (for example, the underlying neurobiology of obsessive-compulsive disorder), but also distal mechanisms (that is, a consideration of how particular neurobiological mechanisms evolved). Evolutionary medicine has emphasized a series of explanations for vulnerability to disease, including constraints, mismatch, and tradeoffs. The current paper will consider compulsive symptoms in obsessive-compulsive and related disorders and behavioral addictions from this evolutionary perspective. It will argue that while obsessive-compulsive disorder (OCD) is typically best conceptualized as a dysfunction, it is theoretically and clinically valuable to understand some symptoms of obsessive-compulsive and related disorders in terms of useful defenses. The symptoms of behavioral addictions can also be conceptualized in evolutionary terms (for example, mismatch), which in turn provides a sound foundation for approaching assessment and intervention. Copyright © 2016. Published by Elsevier B.V.

  8. Remembering the evolutionary Freud.

    Science.gov (United States)

    Young, Allan

    2006-03-01

    Throughout his career as a writer, Sigmund Freud maintained an interest in the evolutionary origins of the human mind and its neurotic and psychotic disorders. In common with many writers then and now, he believed that the evolutionary past is conserved in the mind and the brain. Today the "evolutionary Freud" is nearly forgotten. Even among Freudians, he is regarded to be a red herring, relevant only to the extent that he diverts attention from the enduring achievements of the authentic Freud. There are three ways to explain these attitudes. First, the evolutionary Freud's key work is the "Overview of the Transference Neurosis" (1915). But it was published at an inopportune moment, forty years after the author's death, during the so-called "Freud wars." Second, Freud eventually lost interest in the "Overview" and the prospect of a comprehensive evolutionary theory of psychopathology. The publication of The Ego and the Id (1923), introducing Freud's structural theory of the psyche, marked the point of no return. Finally, Freud's evolutionary theory is simply not credible. It is based on just-so stories and a thoroughly discredited evolutionary mechanism, Lamarckian use-inheritance. Explanations one and two are probably correct but also uninteresting. Explanation number three assumes that there is a fundamental difference between Freud's evolutionary narratives (not credible) and the evolutionary accounts of psychopathology that currently circulate in psychiatry and mainstream journals (credible). The assumption is mistaken but worth investigating.

  9. Electrochemical measurement of tritium and hydrogen permeation through iron membranes

    International Nuclear Information System (INIS)

    Hagi, Hideki; Hayashi, Yasunori

    1987-01-01

    Permeation rates of tritium and hydrogen through iron were measured by the electro-chemical method in which an aqueous solution containing 3.7 x 10 12 Bq/m 3 tritium was used as a cathodic electrolyte. Tritium and hydrogen were introduced from one side of a specimen by cathodic polarization with a constant current density, while at the other side of the specimen the permeated tritium and hydrogen were extracted by potentiostatical ionization. Nearly all of the potentiostatic current on the extraction side is produced by the ionization of hydrogen, because the concentration of tritium in the cathodic electrolyte is very small. The amount of permeated hydrogen was obtained by integrating the potentiostatic current, and that of permeated tritium was determined by measuring the radioactivity of the electrolyte sampled from the anodic side. The separation factor for permeation obtained under steady state conditions (the ratio of permeation rates of hydrogen to tritium divided by the ratio of the concentration of hydrogen to tritium in the cathodic electrolyte) is 12 at 288 K. This value is independent of cathodic current density. Diffusion coefficients of tritium (D T ) and hydrogen (D H ) in iron were determined from the tritium and hydrogen permeation by using time lag technique. For annealed iron at 286 K, D T = 9 x 10 -10 m 2 /s and D H = 4 x 10 -9 m 2 /s, and for 9 % cold-worked iron at 284 K, D T = 3 x 10 -10 m 2 /s and D H = 4 x 10 -10 m 2 /s. (author)

  10. Evolutionary heritage influences Amazon tree ecology

    Science.gov (United States)

    Coelho de Souza, Fernanda; Dexter, Kyle G.; Phillips, Oliver L.; Brienen, Roel J. W.; Chave, Jerome; Galbraith, David R.; Lopez Gonzalez, Gabriela; Monteagudo Mendoza, Abel; Pennington, R. Toby; Poorter, Lourens; Alexiades, Miguel; Álvarez-Dávila, Esteban; Andrade, Ana; Aragão, Luis E. O. C.; Araujo-Murakami, Alejandro; Arets, Eric J. M. M.; Aymard C, Gerardo A.; Baraloto, Christopher; Barroso, Jorcely G.; Bonal, Damien; Boot, Rene G. A.; Camargo, José L. C.; Comiskey, James A.; Valverde, Fernando Cornejo; de Camargo, Plínio B.; Di Fiore, Anthony; Erwin, Terry L.; Feldpausch, Ted R.; Ferreira, Leandro; Fyllas, Nikolaos M.; Gloor, Emanuel; Herault, Bruno; Herrera, Rafael; Higuchi, Niro; Honorio Coronado, Eurídice N.; Killeen, Timothy J.; Laurance, William F.; Laurance, Susan; Lloyd, Jon; Lovejoy, Thomas E.; Malhi, Yadvinder; Maracahipes, Leandro; Marimon, Beatriz S.; Marimon-Junior, Ben H.; Mendoza, Casimiro; Morandi, Paulo; Neill, David A.; Vargas, Percy Núñez; Oliveira, Edmar A.; Lenza, Eddie; Palacios, Walter A.; Peñuela-Mora, Maria C.; Pipoly, John J.; Pitman, Nigel C. A.; Prieto, Adriana; Quesada, Carlos A.; Ramirez-Angulo, Hirma; Rudas, Agustin; Ruokolainen, Kalle; Salomão, Rafael P.; Silveira, Marcos; ter Steege, Hans; Thomas-Caesar, Raquel; van der Hout, Peter; van der Heijden, Geertje M. F.; van der Meer, Peter J.; Vasquez, Rodolfo V.; Vieira, Simone A.; Vilanova, Emilio; Vos, Vincent A.; Wang, Ophelia; Young, Kenneth R.; Zagt, Roderick J.; Baker, Timothy R.

    2016-01-01

    Lineages tend to retain ecological characteristics of their ancestors through time. However, for some traits, selection during evolutionary history may have also played a role in determining trait values. To address the relative importance of these processes requires large-scale quantification of traits and evolutionary relationships among species. The Amazonian tree flora comprises a high diversity of angiosperm lineages and species with widely differing life-history characteristics, providing an excellent system to investigate the combined influences of evolutionary heritage and selection in determining trait variation. We used trait data related to the major axes of life-history variation among tropical trees (e.g. growth and mortality rates) from 577 inventory plots in closed-canopy forest, mapped onto a phylogenetic hypothesis spanning more than 300 genera including all major angiosperm clades to test for evolutionary constraints on traits. We found significant phylogenetic signal (PS) for all traits, consistent with evolutionarily related genera having more similar characteristics than expected by chance. Although there is also evidence for repeated evolution of pioneer and shade tolerant life-history strategies within independent lineages, the existence of significant PS allows clearer predictions of the links between evolutionary diversity, ecosystem function and the response of tropical forests to global change. PMID:27974517

  11. Evolutionary heritage influences Amazon tree ecology.

    Science.gov (United States)

    Coelho de Souza, Fernanda; Dexter, Kyle G; Phillips, Oliver L; Brienen, Roel J W; Chave, Jerome; Galbraith, David R; Lopez Gonzalez, Gabriela; Monteagudo Mendoza, Abel; Pennington, R Toby; Poorter, Lourens; Alexiades, Miguel; Álvarez-Dávila, Esteban; Andrade, Ana; Aragão, Luis E O C; Araujo-Murakami, Alejandro; Arets, Eric J M M; Aymard C, Gerardo A; Baraloto, Christopher; Barroso, Jorcely G; Bonal, Damien; Boot, Rene G A; Camargo, José L C; Comiskey, James A; Valverde, Fernando Cornejo; de Camargo, Plínio B; Di Fiore, Anthony; Elias, Fernando; Erwin, Terry L; Feldpausch, Ted R; Ferreira, Leandro; Fyllas, Nikolaos M; Gloor, Emanuel; Herault, Bruno; Herrera, Rafael; Higuchi, Niro; Honorio Coronado, Eurídice N; Killeen, Timothy J; Laurance, William F; Laurance, Susan; Lloyd, Jon; Lovejoy, Thomas E; Malhi, Yadvinder; Maracahipes, Leandro; Marimon, Beatriz S; Marimon-Junior, Ben H; Mendoza, Casimiro; Morandi, Paulo; Neill, David A; Vargas, Percy Núñez; Oliveira, Edmar A; Lenza, Eddie; Palacios, Walter A; Peñuela-Mora, Maria C; Pipoly, John J; Pitman, Nigel C A; Prieto, Adriana; Quesada, Carlos A; Ramirez-Angulo, Hirma; Rudas, Agustin; Ruokolainen, Kalle; Salomão, Rafael P; Silveira, Marcos; Stropp, Juliana; Ter Steege, Hans; Thomas-Caesar, Raquel; van der Hout, Peter; van der Heijden, Geertje M F; van der Meer, Peter J; Vasquez, Rodolfo V; Vieira, Simone A; Vilanova, Emilio; Vos, Vincent A; Wang, Ophelia; Young, Kenneth R; Zagt, Roderick J; Baker, Timothy R

    2016-12-14

    Lineages tend to retain ecological characteristics of their ancestors through time. However, for some traits, selection during evolutionary history may have also played a role in determining trait values. To address the relative importance of these processes requires large-scale quantification of traits and evolutionary relationships among species. The Amazonian tree flora comprises a high diversity of angiosperm lineages and species with widely differing life-history characteristics, providing an excellent system to investigate the combined influences of evolutionary heritage and selection in determining trait variation. We used trait data related to the major axes of life-history variation among tropical trees (e.g. growth and mortality rates) from 577 inventory plots in closed-canopy forest, mapped onto a phylogenetic hypothesis spanning more than 300 genera including all major angiosperm clades to test for evolutionary constraints on traits. We found significant phylogenetic signal (PS) for all traits, consistent with evolutionarily related genera having more similar characteristics than expected by chance. Although there is also evidence for repeated evolution of pioneer and shade tolerant life-history strategies within independent lineages, the existence of significant PS allows clearer predictions of the links between evolutionary diversity, ecosystem function and the response of tropical forests to global change. © 2016 The Authors.

  12. Attractive evolutionary equilibria

    OpenAIRE

    Roorda, Berend; Joosten, Reinoud

    2011-01-01

    We present attractiveness, a refinement criterion for evolutionary equilibria. Equilibria surviving this criterion are robust to small perturbations of the underlying payoff system or the dynamics at hand. Furthermore, certain attractive equilibria are equivalent to others for certain evolutionary dynamics. For instance, each attractive evolutionarily stable strategy is an attractive evolutionarily stable equilibrium for certain barycentric ray-projection dynamics, and vice versa.

  13. An adaptive ES with a ranking based constraint handling strategy

    Directory of Open Access Journals (Sweden)

    Kusakci Ali Osman

    2014-01-01

    Full Text Available To solve a constrained optimization problem, equality constraints can be used to eliminate a problem variable. If it is not feasible, the relations imposed implicitly by the constraints can still be exploited. Most conventional constraint handling methods in Evolutionary Algorithms (EAs do not consider the correlations between problem variables imposed by the constraints. This paper relies on the idea that a proper search operator, which captures mentioned implicit correlations, can improve performance of evolutionary constrained optimization algorithms. To realize this, an Evolution Strategy (ES along with a simplified Covariance Matrix Adaptation (CMA based mutation operator is used with a ranking based constraint-handling method. The proposed algorithm is tested on 13 benchmark problems as well as on a real life design problem. The outperformance of the algorithm is significant when compared with conventional ES-based methods.

  14. Hydrogen permeation properties of plasma-sprayed tungsten

    International Nuclear Information System (INIS)

    Anderl, R.A.; Pawelko, R.J.; Hankins, M.R.; Longhurst, G.R.; Neiser, R.A.

    1994-01-01

    Tungsten has been proposed as a plasma-facing component material for advanced fusion facilities. This paper reports on laboratory-scale studies that were done to assess the hydrogen permeation properties of plasma-sprayed tungsten for such applications. The work entailed deuterium permeation measurements for plasma-sprayed (PS) tungsten coatings, sputter-deposited (SP) tungsten coatings, and steel substrate material using a mass-analyzed, 3 keV D + 3 ion beam with fluxes of similar 6.5x10 19 D/m 2 s. Extensive characterization analyses for the plasma-sprayed tungsten coatings were made using Auger spectrometry and scanning electron microscopy (SEM). Observed permeation rates through composite PS-tungsten/steel specimens were several orders of magnitude below the permeation levels observed for SP-tungsten/steel composite specimens and pure steel specimens. Characterization analyses indicated that the plasma-sprayed tungsten coating had a nonhomogeneous microstructure that consisted of splats with columnar solidification, partially-melted particles with grain boundaries, and void regions. Reduced permeation levels can be attributed to the complex microstructure and a substantial surface-connected porosity. ((orig.))

  15. Hydrogen permeation properties of plasma-sprayed tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Anderl, R.A. (Idaho National Engineering Lab., EG and G Idaho Inc., Idaho Falls, ID (United States)); Pawelko, R.J. (Idaho National Engineering Lab., EG and G Idaho Inc., Idaho Falls, ID (United States)); Hankins, M.R. (Idaho National Engineering Lab., EG and G Idaho Inc., Idaho Falls, ID (United States)); Longhurst, G.R. (Idaho National Engineering Lab., EG and G Idaho Inc., Idaho Falls, ID (United States)); Neiser, R.A. (Sandia National Laboratories, Albuquerque, NM 87185 (United States))

    1994-09-01

    Tungsten has been proposed as a plasma-facing component material for advanced fusion facilities. This paper reports on laboratory-scale studies that were done to assess the hydrogen permeation properties of plasma-sprayed tungsten for such applications. The work entailed deuterium permeation measurements for plasma-sprayed (PS) tungsten coatings, sputter-deposited (SP) tungsten coatings, and steel substrate material using a mass-analyzed, 3 keV D[sup +][sub 3] ion beam with fluxes of similar 6.5x10[sup 19] D/m[sup 2] s. Extensive characterization analyses for the plasma-sprayed tungsten coatings were made using Auger spectrometry and scanning electron microscopy (SEM). Observed permeation rates through composite PS-tungsten/steel specimens were several orders of magnitude below the permeation levels observed for SP-tungsten/steel composite specimens and pure steel specimens. Characterization analyses indicated that the plasma-sprayed tungsten coating had a nonhomogeneous microstructure that consisted of splats with columnar solidification, partially-melted particles with grain boundaries, and void regions. Reduced permeation levels can be attributed to the complex microstructure and a substantial surface-connected porosity. ((orig.))

  16. Hydrogen permeation properties of plasma-sprayed tungsten*1

    Science.gov (United States)

    Anderl, R. A.; Pawelko, R. J.; Hankins, M. R.; Longhurst, G. R.; Neiser, R. A.

    1994-09-01

    Tungsten has been proposed as a plasma-facing component material for advanced fusion facilities. This paper reports on laboratory-scale studies that were done to assess the hydrogen permeation properties of plasma-sprayed tungsten for such applications. The work entailed deuterium permeation measurements for plasma-sprayed (PS) tungsten coatings, sputter-deposited (SP) tungsten coatings, and steel substrate material using a mass-analyzed, 3 keV D 3+ ion beam with fluxes of ˜6.5 × 10 19 D/m 2 s. Extensive characterization analyses for the plasma-sprayed tungsten coatings were made using Auger spectrometry and scanning electron microscopy (SEM). Observed permeation rates through composite PS-tungsten/steel specimens were several orders of magnitude below the permeation levels observed for SP-tungsten/steel composite specimens and pure steel specimens. Characterization analyses indicated that the plasma-sprayed tungsten coating had a nonhomogeneous microstructure that consisted of splats with columnar solidification, partially-melted particles with grain boundaries, and void regions. Reduced permeation levels can be attributed to the complex microstructure and a substantial surface-connected porosity.

  17. Drug Release and Skin Permeation from Lipid Liquid Crystalline Phases

    Science.gov (United States)

    Costa-Balogh, F. O.; Sparr, E.; Sousa, J. J. S.; Pais, A. A. C. C.

    We have studied drug release and skin permeation from several different liquid crystalline lipid formulations that may be used to control the respective release rates. We have studied the release and permeation through human skin of a water-soluble and amphiphilic drug, propranolol hydrochloride, from several formulations prepared with monoolein and phytantriol as permeation enhancers and controlled release excipients. Diolein and cineol were added to selected formulations. We observed that viscosity decreases with drug load, wich is compatible with the occurrence of phase changes. Diolein stabilizes the bicontinuous cubic phases leading to an increase in viscosity and sustained release of the drug. The slowest release was found for the cubic phases with higher viscosity. Studies on skin permeation showed that these latter formulations also presented lower permeability than the less viscous monoolein lamellar phases. Formulations containing cineol originated higher permeability with higher enhancement ratios. Thus, the various formulations are adapted to different circumstances and delivery routes. While a slow release is usually desired for drug sustained delivery, the transdermal route may require a faster release. Lamellar phases, which are less viscous, are more adapted to transdermal applications. Thus, systems involving lamellar phases of monoolein and cineol are good candidates to be used as skin permeation enhancers for propranolol hydrochloride.

  18. Recent developments in skin mimic systems to predict transdermal permeation.

    Science.gov (United States)

    Waters, Laura J

    2015-01-01

    In recent years there has been a drive to create experimental techniques that can facilitate the accurate and precise prediction of transdermal permeation without the use of in vivo studies. This review considers why permeation data is essential, provides a brief summary as to how skin acts as a natural barrier to permeation and discusses why in vivo studies are undesirable. This is followed by an in-depth discussion on the extensive range of alternative methods that have been developed in recent years. All of the major 'skin mimic systems' are considered including: in vitro models using synthetic membranes, mathematical models including quantitative structure-permeability relationships (QSPRs), human skin equivalents and chromatographic based methods. All of these model based systems are ideally trying to achieve the same end-point, namely a reliable in vitro-in vivo correlation, i.e. matching non-in vivo obtained data with that from human clinical trials. It is only by achieving this aim, that any new method of obtaining permeation data can be acknowledged as a potential replacement for animal studies, for the determination of transdermal permeation. In this review, the relevance and potential applicability of the various models systems will also be discussed.

  19. Permeation of cytotoxic formulations through swatches from selected medical gloves.

    Science.gov (United States)

    Klein, Michael; Lambov, Nikolai; Samev, Nikola; Carstens, Gerhard

    2003-05-15

    The permeability of selected medical glove materials to various cytotoxic agents is described. Fifteen cytotoxic agents were prepared at the highest concentrations normally encountered by hospital personnel. Four single-layer and two double-layer glove systems made of two materials--latex and neoprene--were exposed to the drugs for 30, 60, 90, 120, 150, and 180 minutes. Circular sections of the glove material were cut from the cuff and evaluated without any pretreatment. Permeability tests were conducted in an apparatus consisting of a donor chamber containing the cytotoxic solution and a collection chamber filled with water (the acceptor medium). The two sections were separated by the glove material. Permeating portions, collected in water as the acceptor medium, were analyzed by either ultraviolet-visible light spectrophotometry or high-performance liquid chromatography (HPLC). Permeation rates were calculated on the basis of the concentration of the cytotoxic agent in the acceptor medium. Spectrophotometric measurements were taken every 30 minutes, and HPLC analysis was performed at the end of the three-hour period. Average permeation rates for 14 drugs were low (materials. All glove materials tested were impermeable to most of the cytotoxic agents over a period of three hours. Carmustine was the only agent that substantially permeated single-layer latex glove materials. Permeation of most tested cytotoxic formulations was low through swatches of material from various medical gloves.

  20. Polymorphic Evolutionary Games.

    Science.gov (United States)

    Fishman, Michael A

    2016-06-07

    In this paper, I present an analytical framework for polymorphic evolutionary games suitable for explicitly modeling evolutionary processes in diploid populations with sexual reproduction. The principal aspect of the proposed approach is adding diploid genetics cum sexual recombination to a traditional evolutionary game, and switching from phenotypes to haplotypes as the new game׳s pure strategies. Here, the relevant pure strategy׳s payoffs derived by summing the payoffs of all the phenotypes capable of producing gametes containing that particular haplotype weighted by the pertinent probabilities. The resulting game is structurally identical to the familiar Evolutionary Games with non-linear pure strategy payoffs (Hofbauer and Sigmund, 1998. Cambridge University Press), and can be analyzed in terms of an established analytical framework for such games. And these results can be translated into the terms of genotypic, and whence, phenotypic evolutionary stability pertinent to the original game. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Rise and Persistence of Animal Polyploidy: Evolutionary Constraints and Potential

    Czech Academy of Sciences Publication Activity Database

    Choleva, Lukáš; Janko, Karel

    2013-01-01

    Roč. 140, 2-4 (2013), s. 151-170 ISSN 1424-8581 R&D Projects: GA ČR GPP506/12/P857; GA ČR GAP506/10/1155; GA ČR GA13-12580S Institutional support: RVO:67985904 Keywords : asexual * clonal * hybrid * polyploidization * sexual Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.905, year: 2013

  2. Symmetry-based reciprocity: evolutionary constraints on a proximate mechanism.

    Science.gov (United States)

    Campennì, Marco; Schino, Gabriele

    2016-01-01

    Background. While the evolution of reciprocal cooperation has attracted an enormous attention, the proximate mechanisms underlying the ability of animals to cooperate reciprocally are comparatively neglected. Symmetry-based reciprocity is a hypothetical proximate mechanism that has been suggested to be widespread among cognitively unsophisticated animals. Methods. We developed two agent-based models of symmetry-based reciprocity (one relying on an arbitrary tag and the other on interindividual proximity) and tested their ability both to reproduce significant emergent features of cooperation in group living animals and to promote the evolution of cooperation. Results. Populations formed by agents adopting symmetry-based reciprocity showed differentiated "social relationships" and a positive correlation between cooperation given and received: two common aspects of animal cooperation. However, when reproduction and selection across multiple generations were added to the models, agents adopting symmetry-based reciprocity were outcompeted by selfish agents that never cooperated. Discussion. In order to evolve, hypothetical proximate mechanisms must be able to stand competition from alternative strategies. While the results of our simulations require confirmation using analytical methods, we provisionally suggest symmetry-based reciprocity is to be abandoned as a possible proximate mechanism underlying the ability of animals to reciprocate cooperative interactions.

  3. Orthology and paralogy constraints: satisfiability and consistency

    OpenAIRE

    Lafond, Manuel; El-Mabrouk, Nadia

    2014-01-01

    Background A variety of methods based on sequence similarity, reconciliation, synteny or functional characteristics, can be used to infer orthology and paralogy relations between genes of a given gene family   G . But is a given set   C of orthology/paralogy constraints possible, i.e., can they simultaneously co-exist in an evolutionary history for   G ? While previous studies have focused on full sets of constraints, here we consider the general case where   C does not necessarily involve a ...

  4. Double electrolyte sensor for monitoring hydrogen permeation rate in steels

    Energy Technology Data Exchange (ETDEWEB)

    Ouyang, Y.J. [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Department of Chemistry and Chemical Engineering, Huaihua College, Huaihua 418008 (China); Yu, G., E-mail: yuganghnu@163.co [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Ou, A.L.; Hu, L.; Xu, W.J. [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China)

    2011-06-15

    Highlights: {yields} Designed an amperometric hydrogen sensor with double electrolytes. {yields} Explained the principle of determining hydrogen permeation rate. {yields} Verified good stability, reproducibility and correctness of the developed sensor. {yields} Field on-line monitoring the susceptivity of hydrogen induced cracks. - Abstract: An amperometric hydrogen sensor with double electrolytes composed of a gelatiniform electrolyte and KOH solution has been developed to determine the permeation rate of hydrogen atoms in steel equipment owing to hydrogen corrosion. The gelatiniform electrolyte was made of sodium polyacrylate (PAAS), carboxyl methyl cellulose (CMC) and 0.2 mol dm{sup -3} KOH solution. The results show that the gelatiniform electrolyte containing 50 wt.% polymers has suitable viscosity and high electrical conductivity. The consistent permeation curves were detected by the sensor of the double electrolyte and single liquid KOH electrolyte, respectively. The developed sensor has good stability and reproducibility at room temperature.

  5. Deuterium permeation and diffusion in high-purity beryllium

    International Nuclear Information System (INIS)

    Abramov, E.; Riehm, M.P.; Thompson, D.A.; Smeltzer, W.W.

    1990-01-01

    The permeation rate of deuterium through high-purity beryllium membranes was measured using the gas-driven permeation technique. The time-dependent and the steady-state deuterium flux data were analyzed and the effective diffusivities of the samples were determined. Using multilayer permeation theory the effects of surface oxide were eliminated and the diffusion coefficients of the bulk beryllium determined. The diffusion parameters obtained for the extra-grade beryllium samples (99.8%) are D 0 =6.7x10 -9 m 2 /s and E D =28.4 kJ/mol. For the high-grade beryllium samples (99%) the parameters are D 0 =8.0x10 -9 m 2 /s and E D =35.1 kJ/mol. (orig.)

  6. Deuterium permeation and diffusion in high purity beryllium

    International Nuclear Information System (INIS)

    Abramov, E.

    1990-05-01

    The permeation rate of deuterium through high-purity beryllium membranes was measured using the gas-driven permeation technique. The time-dependent and the steady-state deuterium flux data were analyzed and the effective diffusivities of the samples were determined. A multilayer permeation theory was used in order to eliminate the surface oxide effects and the diffusion coefficients of the bulk beryllium were determined. The diffusion parameters obtained for the extra-grade beryllium samples (99.8%) are D 0 = 6.7 x 10 -9 [m 2 /s] and E D = 28.4 [KJ/mol]; and for the high-grade beryllium samples (99%) the parameters are D 0 = 8.0 x 10 -9 [m 2 /s] and E D = 35.1 [KJ/mol

  7. Double electrolyte sensor for monitoring hydrogen permeation rate in steels

    International Nuclear Information System (INIS)

    Ouyang, Y.J.; Yu, G.; Ou, A.L.; Hu, L.; Xu, W.J.

    2011-01-01

    Highlights: → Designed an amperometric hydrogen sensor with double electrolytes. → Explained the principle of determining hydrogen permeation rate. → Verified good stability, reproducibility and correctness of the developed sensor. → Field on-line monitoring the susceptivity of hydrogen induced cracks. - Abstract: An amperometric hydrogen sensor with double electrolytes composed of a gelatiniform electrolyte and KOH solution has been developed to determine the permeation rate of hydrogen atoms in steel equipment owing to hydrogen corrosion. The gelatiniform electrolyte was made of sodium polyacrylate (PAAS), carboxyl methyl cellulose (CMC) and 0.2 mol dm -3 KOH solution. The results show that the gelatiniform electrolyte containing 50 wt.% polymers has suitable viscosity and high electrical conductivity. The consistent permeation curves were detected by the sensor of the double electrolyte and single liquid KOH electrolyte, respectively. The developed sensor has good stability and reproducibility at room temperature.

  8. Control of tritium permeation through fusion reactor strucural materials

    International Nuclear Information System (INIS)

    Maroni, V.A.

    1978-01-01

    The intention of this paper is to provide a brief synopsis of the status of understanding and technology pertaining to the dissolution and permeation of tritium in fusion reactor materials. The following sections of this paper attempt to develop a simple perspective for understanding the consequences of these phenomena and the nature of the technical methodology being contemplated to control their impact on fusion reactor operation. Considered in order are: (1) the occurrence of tritium in the fusion fuel cycle, (2) a set of tentative criteria to guide the analysis of tritium containment and control strategies, (3) the basic mechanisms by which tritium may be released from a fusion plant, and (4) the methods currently under development to control the permeation-related release mechanisms. To provide background and support for these considerations, existing solubility and permeation data for the hydrogen isotopes are compared and correlated under conditions to be expected in fusion reactor systems

  9. Permeation of "Hydromer" Film: An Elastomeric Hydrogen-Capturing Biopolymer.

    Energy Technology Data Exchange (ETDEWEB)

    Karnesky, Richard A. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Friddle, Raymond William [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Whaley, Josh A. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Smith, Geoffrey [New Mexico State Univ., Las Cruces, NM (United States)

    2015-12-01

    This report analyzes the permeation resistance of a novel and proprietary polymer coating for hydrogen isotope resistance that was developed by New Mexico State University. Thermal gravimetric analysis and thermal desoprtion spectroscopy show the polymer is stable thermally to approximately 250 deg C. Deuterium gas-driven permeation experiments were conducted at Sandia to explore early evidence (obtained using Brunauer - Emmett - Teller) of the polymer's strong resistance to hydrogen. With a relatively small amount of the polymer in solution (0.15%), a decrease in diffusion by a factor of 2 is observed at 100 and 150 deg C. While there was very little reduction in permeability, the preliminary findings reported here are meant to demonstrate the sensitivity of Sandia's permeation measurements and are intended to motivate the future exploration of thicker barriers with greater polymer coverage.

  10. The formation of tritium permeation barriers by CVD

    International Nuclear Information System (INIS)

    Forcey, K.S.; Perujo, A.; Reiter, F.; Lolli-Ceroni, P.L.

    1993-01-01

    The effectiveness as permeation barriers of the following CVD coatings have been investigated: TiC (1 to 2 μm in thickness); a bi-layer of TiN on TiC (3 μm total thickness) and CVD Al 2 O 3 on a TiN/TiC bi-layer. The substrate materials were TZM (a Mo alloy) and 316L stainless steel in the form of discs of diameter 48 mm and thickness 0.1 or 1 mm. Permeation measurements were performed in the temperature range 515-742 K using deuterium at pressures in the range 1-50 kPa. CVD layers were shown to form reasonably effective permeation barriers. At a temperature of 673 K TiC is around 6000 times less permeable to deuterium than 316L stainless steel. (orig.)

  11. Ion-driven deuterium permeation through tungsten at high temperatures

    Science.gov (United States)

    Gasparyan, Yu. M.; Golubeva, A. V.; Mayer, M.; Pisarev, A. A.; Roth, J.

    2009-06-01

    The ion-driven permeation (IDP) through 50 μm thick pure tungsten foils was measured in the temperature range of 823-923 K during irradiation by 200 eV/D + ion beam with a flux of 10 17-10 18 D/m 2s. Gas driven permeation (GDP) from the deuterium background gas was observed as well. Calculations using both the analytical formula for the diffusion limited regime (DLR) and the TMAP 7 code gave good agreement with the experimental data. Defects with a detrapping energy of (2.05 ± 0.15) eV were found to limit the permeation lag time in our experimental conditions.

  12. Ion-driven deuterium permeation through tungsten at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Gasparyan, Yu.M., E-mail: yury.gasparyan@ipp.mpg.d [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmanstrasse 2, D-85748 Garching (Germany); Moscow Engineering and Physics Institute, Kashirskoe sh. 31, Moscow 115409 (Russian Federation); Golubeva, A.V. [RRC ' Kurchatov Institute' , Ac. Kurchatov sq., 1/1, Moscow RU-123182 (Russian Federation); Mayer, M. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmanstrasse 2, D-85748 Garching (Germany); Pisarev, A.A. [Moscow Engineering and Physics Institute, Kashirskoe sh. 31, Moscow 115409 (Russian Federation); Roth, J. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmanstrasse 2, D-85748 Garching (Germany)

    2009-06-15

    The ion-driven permeation (IDP) through 50 mum thick pure tungsten foils was measured in the temperature range of 823-923 K during irradiation by 200 eV/D{sup +} ion beam with a flux of 10{sup 17}-10{sup 18} D/m{sup 2}s. Gas driven permeation (GDP) from the deuterium background gas was observed as well. Calculations using both the analytical formula for the diffusion limited regime (DLR) and the TMAP 7 code gave good agreement with the experimental data. Defects with a detrapping energy of (2.05 +- 0.15) eV were found to limit the permeation lag time in our experimental conditions.

  13. Ion-driven deuterium permeation through tungsten at high temperatures

    International Nuclear Information System (INIS)

    Gasparyan, Yu.M.; Golubeva, A.V.; Mayer, M.; Pisarev, A.A.; Roth, J.

    2009-01-01

    The ion-driven permeation (IDP) through 50 μm thick pure tungsten foils was measured in the temperature range of 823-923 K during irradiation by 200 eV/D + ion beam with a flux of 10 17 -10 18 D/m 2 s. Gas driven permeation (GDP) from the deuterium background gas was observed as well. Calculations using both the analytical formula for the diffusion limited regime (DLR) and the TMAP 7 code gave good agreement with the experimental data. Defects with a detrapping energy of (2.05 ± 0.15) eV were found to limit the permeation lag time in our experimental conditions.

  14. Electrochemical measurement of tritium and hydrogen permeation through iron membranes

    International Nuclear Information System (INIS)

    Hagi, Hideki; Hayashi, Yasunori

    1988-01-01

    Permeation rates of tritium and hydrogen through iron were measured by the electrochemical method in which an aqueous solution containing 3.7 x 10 12 Bq/m 3 tritium was used as a cathodic electrolyte. Tritium and hydrogen were introduced from one side of a specimen by cathodic polarization with a constant current density, while at the other side of the specimen the permeated tritium and hydrogen were extracted by potentiostatical ionization. Nearly all of the potentiostatic current of the extraction side stands for the ionization of hydrogen, because the concentration of tritium in the cathodic electrolyte is very small. The amount of permeated hydrogen was obtained by integrating the anodic current, and that of tritium was determined by measuring the radioactivity of the electrolyte sampled from the extraction side. The separation factor for permeation obtained under steady state conditions (the ratio of permeation rates of hydrogen to tritium divided by the ratio of the concentration of hydrogen to tritium in the charging electrolyte) is 12 at 288 K. This value is independent of cathodic current density. Diffusion coefficients of tritium (D T ) and hydrogen (D H ) in iron were determined from the time lag of tritium and hydrogen permeation. For annealed specimens at 286 K, D T = 9 x 10 -10 m 2 /s and D H = 4 x 10 -9 m 2 /s, and for 9% cold-worked specimens at 284 K, D T = 3 x 10 -10 m 2 /s and D H = 4 x 10 -10 m 2 /s. (author)

  15. Tritium inventory and permeation in the ITER breeding blanket

    International Nuclear Information System (INIS)

    Violante, V.; Tosti, S.; Sibilia, C.; Felli, F.; Casadio, S.; Alvani, C.

    2000-01-01

    A model has allowed us to perform the analysis of the tritium inventory and permeation in the international thermonuclear experimental reactor (ITER) breeding blanket under the hypothesis of steady state conditions. Li 2 ZrO 3 (reference) and Li 2 TiO 3 (alternative) have been studied as breeding materials. The total breeder inventory assessed is 7.64 g for the Li 2 ZrO 3 at reference temperature. The model has also been used for a parametric analysis of the tritium permeation. At reference temperature and purge helium velocity of 0.01 m/s, the HT partial pressure is ranging from 10 to 30 Pa in the breeder and 1.5x10 -3 Pa in the beryllium. At 0.1 m/s of purge helium velocity, the HT partial pressure is reduced of one order by magnitude in the breeder and becomes 5x10 -5 Pa in the beryllium. The tritium permeation into the coolant for the whole blanket is ranging from 100 to 250 mCi per day for purge helium velocity of 0.01 m/s. The analysis of the tritium inventory and permeation for the alternative Li 2 TiO 3 breeding material has been carried out too. The tritium inventory in the breeder is in the range from 6 to 375 g larger than in Li 2 ZrO 3 by about a factor 5; the tritium permeation into coolant is comparable to the Li 2 ZrO 3 one. This analysis provides indications on the influence of the operating parameters on the tritium control in the ITER breeding blanket; particularly the control of the tritium inventory by the temperature and the tritium permeation by the purge gas velocity

  16. Implantation measurements to determine tritium permeation in first wall structures

    International Nuclear Information System (INIS)

    Holland, D.F.; Causey, R.A.

    1983-01-01

    A principal safety concern for a D-T burning fusion reactor is release of tritium during routine operation. Tritium implantation into first wall structures, and subsequent permeation into coolants, is potentially an important source of tritium loss. This paper reports on an experiment in which an ion accelerator was used to implant deuterium atoms in a stainless steel disk to simulate tritium implantation in first wall structures. The permeation rate was measured under various operating conditions. These results were used in the TMAP computer code to determine potential tritium loss rates for fusion reactors

  17. Permeation Barrier Coatings for the Helical Heat Exchanger

    International Nuclear Information System (INIS)

    Korinko, P.S.

    1999-01-01

    A permeation barrier coating was specified for the Helical Heat Exchanger (HHE) to minimize contamination through emissions and/or permeation into the nitrogen system for ALARA reasons. Due to the geometry of the HHE, a special coating practice was needed since the conventional method of high temperature pack aluminization was intractable. A survey of many coating companies was undertaken; their coating capabilities and technologies were assessed and compared to WSRC needs. The processes and limitations to coating the HHE are described. Slurry coating appears to be the most technically sound approach for coating the HHE

  18. Origins of evolutionary transitions

    Indian Academy of Sciences (India)

    2014-03-15

    Mar 15, 2014 ... ... of events: 'Entities that were capable of independent replication ... There have been many major evolutionary events that this definition of .... selection at level x to exclusive selection at x – will probably require a multiplicity ...

  19. Evolutionary relationships among Astroviridae

    NARCIS (Netherlands)

    Lukashov, Vladimir V.; Goudsmit, Jaap

    2002-01-01

    To study the evolutionary relationships among astroviruses, all available sequences for members of the family Astroviridae were collected. Phylogenetic analysis distinguished two deep-rooted groups: one comprising mammalian astroviruses, with ovine astrovirus being an outlier, and the other

  20. Evolutionary Multiplayer Games

    OpenAIRE

    Gokhale, Chaitanya S.; Traulsen, Arne

    2014-01-01

    Evolutionary game theory has become one of the most diverse and far reaching theories in biology. Applications of this theory range from cell dynamics to social evolution. However, many applications make it clear that inherent non-linearities of natural systems need to be taken into account. One way of introducing such non-linearities into evolutionary games is by the inclusion of multiple players. An example is of social dilemmas, where group benefits could e.g.\\ increase less than linear wi...

  1. Permeation of deuterium implanted into V-15Cr-5Ti

    International Nuclear Information System (INIS)

    Anderl, R.A.; Longhurst, G.R.; Struttmann, D.A.

    1987-01-01

    Permeation and reemission of deuterium for the vanadium alloy, V-15Cr-5Ti, was investigated using 3 keV, D 3 + ion beams from a small accelerator. The experiments consisted of measurement of the deuterium reemission and permeation rates as a function of implantation fluence for 0.5 mm thick specimens heated to temperatures from 623 K to 823 K. Implantation-side surface characterization was made by simultaneous measurements of sputtered ions with a secondary ion mass spectrometer (SIMS). For the experimental conditions used, the steady-state deuterium permeation flux in V-15Cr-5Ti is approximately 18% of the implantation flux. This is approximately 1000 times that seen in the austenitic stainless steel, PCA, and 200 times that seen in the ferritic steel, HT-9, under comparable conditions. Measurement of deuterium diffusivity in V-15Cr-5Ti using permeation break-through times indicates that D = 1.4x10 -8 exp(-0.11 eV/kT)(m 2 /s), over the temperature range 723 K to 823 K. (orig.)

  2. Hydrogen ion-driven permeation in carbonaceous films

    International Nuclear Information System (INIS)

    Anderl, R.A.; Holland, D.F.; Longhurst, G.R.

    1989-01-01

    This paper presents the results of investigations into the permeation properties of amorphous carbonaceous, a-C:H, films produced by plasmachemical deposition techniques. Carbonaceous films on iron substrates with thickness ranging from 60 nm to 110 nm were subjected to high fluence implantations with mass analyzed D 3 + ions with energies ranging from 600 eV to 3000 eV and fluxes ranging from 5x10 14 D/cm 2 s to 5x10 15 D/cm 2 s, respectively. Deuterium re-emission upstream, deuterium permeation downstream and secondary ions sputtered from the implantation surface were measured as a function of implantation fluence for specimens at 420 K. The present studies indicate that the a-C:H film permeability is directly related to the time, hence the fluence, required to achieve isotopic replacement and saturation of the deuterium ion beam atoms stopped in the implant region. Once the deuterium saturation level is achieved in the layer, a significant fraction of the implanting ions can result in permeation. For the present experiment, this permeation factor was much higher than that for uncoated iron specimens subjected to similar beam conditions. Carbon sputter yields of 0.008-0.01 C/D were determined in this work for 1000-eV to 400-eV deuterium ions incident on a-C:H films. (orig.)

  3. Permeation of deuterium implanted into V-15Cr-5Ti

    Science.gov (United States)

    Anderl, R. A.; Longhurst, G. R.; Struttmann, D. A.

    1987-02-01

    Permeation and reemission of deuterium for the vanadium alloy, V-15Cr-5Ti, was investigated using 3 keV, D 3+ ion beams from a small accelerator. The experiments consisted of measurement of the deuterium reemission and permeation rates as a function of implantation fluence for 0.5 mm thick specimens heated to temperatures from 623 K to 823 K. Implantation-side surface characterization was made by simultaneous measurements of sputtered ions with a secondary ion mass spectrometer (SIMS). For the experimental conditions used, the steady-state deuterium permeation flux in V-15Cr-5Ti is approximately 18% of the implantation flux. This is approximately 1000 times that seen in the austenitic stainless steel, PCA, and 200 times that seen in the ferritic steel, HT-9, under comparable conditions. Measurement of deuterium diffusivity in V-15Cr-5Ti using permeation break-through times indicates that D = 1.4 × 10 -8 exp( -0.11 eV/ kT) (m 2/s), over the temperature range 723 K to 823 K.

  4. Hydrogen ion-driven permeation in carbonaceous films

    Energy Technology Data Exchange (ETDEWEB)

    Anderl, R.A.; Holland, D.F.; Longhurst, G.R.

    1989-04-01

    This paper presents the results of investigations into the permeation properties of amorphous carbonaceous, a-C:H, films produced by plasmachemical deposition techniques. Carbonaceous films on iron substrates with thickness ranging from 60 nm to 110 nm were subjected to high fluence implantations with mass analyzed D/sub 3//sup +/ ions with energies ranging from 600 eV to 3000 eV and fluxes ranging from 5x10/sup 14/ D/cm/sup 2/ s to 5x10/sup 15/ D/cm/sup 2/ s, respectively. Deuterium re-emission upstream, deuterium permeation downstream and secondary ions sputtered from the implantation surface were measured as a function of implantation fluence for specimens at 420 K. The present studies indicate that the a-C:H film permeability is directly related to the time, hence the fluence, required to achieve isotopic replacement and saturation of the deuterium ion beam atoms stopped in the implant region. Once the deuterium saturation level is achieved in the layer, a significant fraction of the implanting ions can result in permeation. For the present experiment, this permeation factor was much higher than that for uncoated iron specimens subjected to similar beam conditions. Carbon sputter yields of 0.008-0.01 C/D were determined in this work for 1000-eV to 400-eV deuterium ions incident on a-C:H films. (orig.).

  5. Hydrogen ion-driven permeation in carbonaceous films

    Science.gov (United States)

    Anderl, R. A.; Holland, D. F.; Longhurst, G. R.

    1989-04-01

    This paper presents the results of investigations into the permeation properties of amorphous carbonaceous, a-C: H, films produced by plasmachemical deposition techniques. Carbonaceous films on iron substrates with thickness ranging from 60 nm to 110 nm were subjected to high fluence implantations with mass analyzed D +3 ions with energies ranging from 600 eV to 3000 eV and fluxes ranging from 5 × 10 14D/ cm2 s to 5 × 10 15D/ cm2 s, respectively. Deuterium re-emission upstream, deuterium permeation downstream and secondary ions sputtered from the implantation surface were measured as a function of implantation fluence for specimens at 420 K. The present studies indicate that the a-C : H film permeability is directly related to the time, hence the fluence, required to achieve isotopic replacement and saturation of the deuterium ion beam atoms stopped in the implant region. Once the deuterium saturation level is achieved in the layer, a significant fraction of the implanting ions can result in permeation. For the present experiment, this permeation factor was much higher than that for uncoated iron specimens subjected to similar beam conditions. Carbon sputter yields of 0.008-0.01 C/D were determined in this work for 1000-eV to 400-eV deuterium ions incident on a-C : H films.

  6. Permeation of deuterium implanted into V-15Cr-5Ti

    Energy Technology Data Exchange (ETDEWEB)

    Anderl, R.A.; Longhurst, G.R.; Struttmann, D.A.

    1987-02-01

    Permeation and reemission of deuterium for the vanadium alloy, V-15Cr-5Ti, was investigated using 3 keV, D/sub 3//sup +/ ion beams from a small accelerator. The experiments consisted of measurement of the deuterium reemission and permeation rates as a function of implantation fluence for 0.5 mm thick specimens heated to temperatures from 623 K to 823 K. Implantation-side surface characterization was made by simultaneous measurements of sputtered ions with a secondary ion mass spectrometer (SIMS). For the experimental conditions used, the steady-state deuterium permeation flux in V-15Cr-5Ti is approximately 18% of the implantation flux. This is approximately 1000 times that seen in the austenitic stainless steel, PCA, and 200 times that seen in the ferritic steel, HT-9, under comparable conditions. Measurement of deuterium diffusivity in V-15Cr-5Ti using permeation break-through times indicates that D = 1.4x10/sup -8/ exp(-0.11 eVkT)(m/sup 2/s), over the temperature range 723 K to 823 K.

  7. In vitro-in vivo correlation in skin permeation.

    Science.gov (United States)

    Mohammed, D; Matts, P J; Hadgraft, J; Lane, M E

    2014-02-01

    In vitro skin permeation studies have been used extensively in the development and optimisation of delivery of actives in vivo. However, there are few reported correlations of such in vitro studies with in vivo data. The aim of this study was to investigate the skin permeation of a model active, niacinamide, both in vitro and in vivo. Conventional diffusion cell studies were conducted in human skin to determine niacinamide permeation from a range of vehicles which included dimethyl isosorbide (DMI), propylene glycol (PG), propylene glycol monolaurate (PGML), N-methyl 2-pyrrolidone (NMP), Miglyol 812N® (MG), and mineral oil (MO). Single, binary or ternary systems were examined. The same vehicles were subsequently examined to investigate niacinamide delivery in vivo. For this proof-of-concept study one donor was used for the in vitro studies and one volunteer for the in vivo investigations to minimise biovariability. Analysis of in vitro samples was conducted using HPLC and in vivo uptake of niacinamide was evaluated using Confocal Raman spectroscopy (CRS). The amount of niacinamide permeated through skin in vitro was linearly proportional to the intensity of the niacinamide signal determined in the stratum corneum in vivo. A good correlation was observed between the signal intensities of selected vehicles and niacinamide signal intensity. The findings provide further support for the use of CRS to monitor drug delivery into and across the skin. In addition, the results highlight the critical role of the vehicle and its disposition in skin for effective dermal delivery.

  8. Mechanisms of oxygen permeation through plastic films and barrier coatings

    Science.gov (United States)

    Wilski, Stefan; Wipperfürth, Jens; Jaritz, Montgomery; Kirchheim, Dennis; Mitschker, Felix; Awakowicz, Peter; Dahlmann, Rainer; Hopmann, Christian

    2017-10-01

    Oxygen and water vapour permeation through plastic films in food packaging or other applications with high demands on permeation are prevented by inorganic barrier films. Most of the permeation occurs through small defects (visualized by etching with reactive oxygen in a capacitively coupled plasma and subsequent SEM imaging. In this work, defects in SiO x -coatings deposited by plasma-enhanced chemical vapour deposition on polyethylene terephthalate (PET) are investigated and the mass transport through the polymer is simulated in a 3D approach. Calculations of single defects showed that there is no linear correlation between the defect area and the resulting permeability. The influence of adjacent defects in different distances was observed and led to flow reduction functions depending on the defect spacing and defect area. A critical defect spacing where no interaction between defects occurs was found and compared to other findings. According to the superposition principle, the permeability of single defects was added up and compared to experimentally determined oxygen permeation. The results showed the same trend of decreasing permeability with decreasing defect densities.

  9. The formation of hydrogen permeation barriers on steels by aluminising

    Science.gov (United States)

    Forcey, K. S.; Ross, D. K.; Wu, C. H.

    1991-06-01

    An extensive investigation has been carried out into the effectiveness of aluminised layers as permeation barriers on AISI 316L stainless and DIN 1.4914 martensitic steels. The study involved measurement of the hydrogen permeation rate through commercially aluminised steel discs of thicknesses in the range 1-1.6 mm, at temperatures between 250 and 600 °C and for an upstream hydrogen pressure of 10 5 Pa. The composition and structure of the aluminide layers were investigated by a number of techniques such as SEM, electron beam microprobe and X-ray diffraction. Accelerator based techniques such as RBS and NRA were employed to study the top micron or so of the surfaces of the samples. By these techniques it was found that the effectiveness of the permeation barrier depended on the formation of a thin surface oxide layer consisting of Al 2O 3. It was found that the permeation rate through the aluminised steels could be reduced by 3-4 orders of magnitude by forming a surface oxide layer up to a micron or so in thickness.

  10. Hydrogen permeation behavior through F82H at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, S.; Katayama, K.; Shimozori, M.; Fukada, S. [Interdisciplinary Graduate School of Engineering Science, Kyushu University, Kyushu (Japan); Ushida, H. [Energy Science and Engineering, Faculty of Engineering, Kyushu University, Kyushu (Japan); Nishikawa, M. [Malaysia-Japan International Institute of Technology, UTM, Kuala Lumpur (Malaysia)

    2015-03-15

    F82H is a primary candidate of structural material and coolant pipe material in a blanket of a fusion reactor. Understanding tritium permeation behavior through F82H is important. In a normal operation of a fusion reactor, the temperature of F82H will be controlled below 550 C. degrees because it is considered that F82H can be used up to 30,000 hours at 550 C. degrees. However, it is necessary to assume the situation where F82H is heated over 550 C. degrees in a severe accident. In this study, hydrogen permeation behavior through F82H was investigated in the temperature range from 500 to 800 C. degrees. In some cases, water vapor was added in a sample gas to investigate an effect of water vapor on hydrogen permeation. The permeability of hydrogen in the temperature range from 500 to 700 C. degrees agreed well with the permeability reported by E. Serra et al. The degradation of the permeability by water vapor was not observed. After the hydrogen permeation reached in a steady state at 700 C. degrees, the F82H sample was heated to 800 C. degrees. The permeability of hydrogen through F82H sample which was once heated up to 800 C. degrees was lower than that of the original one. (authors)

  11. GAS PERMEATION PROPERTIES OF POLY(LACTIC ACID). (R826733)

    Science.gov (United States)

    AbstractThe need for the development of polymeric materials based on renewable resources has led to the development of poly(lactic acid) (PLA) which is being produced from a feedstock of corn rather than petroleum. The present study examines the permeation of nitrogen...

  12. Phase Change Permeation Technology For Environmental Control Life Support Systems

    Science.gov (United States)

    Wheeler, Raymond M.

    2014-01-01

    Use of a phase change permeation membrane (Dutyion [Trademark]) to passively and selectively mobilize water in microgravity to enable improved water recovery from urine/brine for Environment Control and Life Support Systems (ECLSS) and water delivery to plans for potential use in microgravity.

  13. In vitro permeation of platinum through African and Caucasian skin.

    Science.gov (United States)

    Franken, A; Eloff, F C; du Plessis, J; Badenhorst, C J; Du Plessis, J L

    2015-02-03

    The majority of the South African workforce are Africans, therefore potential racial differences should be considered in risk and exposure assessments in the workplace. Literature suggests African skin to be a superior barrier against permeation and irritants. Previous in vitro studies on metals only included skin from Caucasian donors, whereas this study compared the permeation of platinum through African and Caucasian skin. A donor solution of 0.3 mg/ml of potassium tetrachloroplatinate (K₂PtCl₄) dissolved in synthetic sweat was applied to the vertical Franz diffusion cells with full thickness abdominal skin. Skin from three female African and three female Caucasian donors were included (n=21). The receptor solution was removed at various intervals during the 24 h experiment, and analysed with high resolution inductively coupled plasma-mass spectrometry (ICP-MS). Skin was digested and analysed by inductively coupled plasma-optical emission spectrometry (ICP-OES). Significantly higher permeation of platinum through intact African skin (p=0.044), as well as a significantly higher mass of platinum retention in African skin in comparison with Caucasian skin (p=0.002) occurred. Significant inter-donor variation was found in both racial groups (pskin and further investigation is necessary to explain the higher permeation through African skin. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  14. Permeation of supercritical carbon dioxide through polymeric hollow fiber membranes

    NARCIS (Netherlands)

    Patil, V.E.; Broeke, van den L.J.P.; Vercauteren, F.F.; Keurentjes, J.T.F.

    2006-01-01

    Permeation of carbon dioxide was measured for two types of composite polymeric hollow fiber membranes for feed pressures up to 18 MPa at a temp. of 313 K. support membrane. The membranes consist of a polyamide copolymer (IPC) layer or a poly(vinyl alc.) (PVA) layer on top of a polyethersulfone

  15. Mechanisms of oxygen permeation through plastic films and barrier coatings

    International Nuclear Information System (INIS)

    Wilski, Stefan; Wipperfürth, Jens; Jaritz, Montgomery; Kirchheim, Dennis; Dahlmann, Rainer; Hopmann, Christian; Mitschker, Felix; Awakowicz, Peter

    2017-01-01

    Oxygen and water vapour permeation through plastic films in food packaging or other applications with high demands on permeation are prevented by inorganic barrier films. Most of the permeation occurs through small defects (<3 µ m) in the barrier coating. The defects were visualized by etching with reactive oxygen in a capacitively coupled plasma and subsequent SEM imaging. In this work, defects in SiO x -coatings deposited by plasma-enhanced chemical vapour deposition on polyethylene terephthalate (PET) are investigated and the mass transport through the polymer is simulated in a 3D approach. Calculations of single defects showed that there is no linear correlation between the defect area and the resulting permeability. The influence of adjacent defects in different distances was observed and led to flow reduction functions depending on the defect spacing and defect area. A critical defect spacing where no interaction between defects occurs was found and compared to other findings. According to the superposition principle, the permeability of single defects was added up and compared to experimentally determined oxygen permeation. The results showed the same trend of decreasing permeability with decreasing defect densities. (paper)

  16. Preventing method and device for underground permeation of hazardous material

    International Nuclear Information System (INIS)

    Funabashi, Kiyomi; Kurokawa, Hideaki; Fukazawa, Tetsuo; Yamazaki, Tadashi.

    1996-01-01

    In a method of preventing hazardous materials from permeating into ground by burying adsorbing materials underground, a plurality of adsorbing layers are laminated being spaced apart from each other, the concentration of the hazardous materials between each of the adsorbent layers is measured. When the concentration reaches a predetermined value, the adsorbent layers are regenerated. A suppression means for preventing hazardous materials from permeating into the ground are formed by an upper adsorbent layer and a lower adsorbent layer, and a means for measuring the concentration of hazardous materials passing through the upper adsorbent layer and a means for charging and discharging regenerated liquid are disposed. When it is detected that the poisonous materials can not be eliminated, the poisonous materials are already permeated to the adsorbent layer, and they start to inflow into underground water. In order to prevent it, an adsorbent layer is additionally disposed at the lower side of the place of detection to eliminate the poisonous materials completely thereby enabling to prevent poisonous materials from permeating into underground for a long period of time. (T.M.)

  17. Permeation of Mixed Penetrants through Glassy Polymer Membranes.

    Science.gov (United States)

    1985-03-15

    and LOPE. Also, ESCA was used in conjunction with plasma etching to determine the effects of the gas phase fluorine concentration and fluorination...at 35 3C. ARD-AISS5 65 PERMEATION OF MIXED PENETRANTS THROUGH GLASSY POLYMER 213 MENBRANES (U) NORTH CAROLINA STATE UNIV AT RALEIGH R T CHERN ET AL. 15

  18. Comparing pervaporation and vapor permeation hybrid distillation processes

    NARCIS (Netherlands)

    Fontalvo, J.; Cuellar, P.; Timmer, J.M.K.; Vorstman, M.A.G.; Wijers, J.G.; Keurentjes, J.T.F.

    2005-01-01

    Previous studies have shown that hybrid distillation processes using either pervaporation or vapor permeation can be very attractive for the separation of mixtures. In this paper, a comparison between these two hybrid processes has been made. A tool has been presented that can assist designers and

  19. Permeated defect detecting test method and device in reactor

    International Nuclear Information System (INIS)

    Sakurai, Yoshishige.

    1996-01-01

    The present invention provides a method of and a device capable of performing a test for entire inner surfaces of the reactor upon periodical inspection of a BWR type reactor while sufficiently taking countermeasures for radiation rays into consideration. Namely, the present invention comprises following steps. (1) A provisional step for taking a shroud head of a reactor core shroud and incore structural components above and below the shroud out of the reactor, discharging reactor water and water tightly closing openings such as reactor wall perforation holes, (2) a pretreatment step for washing exposed inner surfaces of the reactor and peeling deteriorated materials, (3) a first drying step for drying portions washed and peeled in the step (2), (4) a permeation step for applying a permeation liquid of a defect detecting medium on the exposed inner surfaces of the reactor, (5) a permeation liquid removing step for removing the an excess permeation liquid in the step (4), (6) a second drying step for drying corresponding portions after performing the step (5), and (7) a flaw detecting step for optically observing the corresponding portions after performing the step (6) and detecting flaws. (I.S.)

  20. In vitro permeation of platinum and rhodium through Caucasian skin.

    Science.gov (United States)

    Franken, A; Eloff, F C; Du Plessis, J; Badenhorst, C J; Jordaan, A; Du Plessis, J L

    2014-12-01

    During platinum group metals (PGMs) refining the possibility exists for dermal exposure to PGM salts. The dermal route has been questioned as an alternative route of exposure that could contribute to employee sensitisation, even though literature has been focused on respiratory exposure. This study aimed to investigate the in vitro permeation of platinum and rhodium through intact Caucasian skin. A donor solution of 0.3mg/ml of metal, K2PtCl4 and RhCl3 respectively, was applied to the vertical Franz diffusion cells with full thickness abdominal skin. The receptor solution was removed at various intervals during the 24h experiment, and analysed with high resolution ICP-MS. Skin was digested and analysed by ICP-OES. Results indicated cumulative permeation with prolonged exposure, with a significantly higher mass of platinum permeating after 24h when compared to rhodium. The mass of platinum retained inside the skin and the flux of platinum across the skin was significantly higher than that of rhodium. Permeated and skin retained platinum and rhodium may therefore contribute to sensitisation and indicates a health risk associated with dermal exposure in the workplace. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Effect of piperidones on hydrogen permeation and corrosion ...

    Indian Academy of Sciences (India)

    corrosion inhibition. 3.5 Hydrogen permeation measurements. Hydrogen can enter into the metal during various industrial operations like melting, heat treatment, or pickling and electrochemical processes such as cathodic cleaning and electrolytic machining. Of the various sources of entry of hydrogen into the metal,.

  2. Development of a plasma driven permeation experiment for TPE

    Energy Technology Data Exchange (ETDEWEB)

    Buchenauer, Dean, E-mail: dabuche@sandia.gov [Sandia National Laboratories, Livermore, CA (United States); Kolasinski, Robert [Sandia National Laboratories, Livermore, CA (United States); Shimada, Masa [Idaho National Laboratory, Idaho Falls, ID (United States); Donovan, David [Sandia National Laboratories, Livermore, CA (United States); Youchison, Dennis [Sandia National Laboratories, Albuquerque, NM (United States); Merrill, Brad [Idaho National Laboratory, Idaho Falls, ID (United States)

    2014-10-15

    Highlights: • We have designed and fabricated a novel tritium permeation membrane holder for use in the Tritium Plasma Experiment (TPE). • The membrane temperature is controlled by varying the cooling flow rate and proximity of a spiral cooling channel. • Sealing tests have demonstrated adequate helium leak rates up to temperatures of 1000 °C. • Flow modeling indicates a minimal helium pressure drop across the membrane holder (<700 Pa). • Thermal modeling shows good heat removal and minimal membrane temperature variation (±2%) even up to peak TPE ion fluxes. - Abstract: Experiments on retention of hydrogen isotopes (including tritium) at temperatures less than 800 °C have been carried out in the Tritium Plasma Experiment (TPE) at Idaho National Laboratory [1,2]. To provide a direct measurement of plasma driven permeation in plasma facing materials at temperatures reaching 1000 °C, a new TPE membrane holder has been built to hold test specimens (≤1 mm in thickness) at high temperature while measuring tritium permeating through the membrane from the plasma facing side. This measurement is accomplished by employing a carrier gas that transports the permeating tritium from the backside of the membrane to ion chambers giving a direct measurement of the plasma driven tritium permeation rate. Isolation of the membrane cooling and sweep gases from TPE's vacuum chamber has been demonstrated by sealing tests performed up to 1000 °C of a membrane holder design that provides easy change out of membrane specimens between tests. Simulations of the helium carrier gas which transports tritium to the ion chamber indicate a very small pressure drop (∼700 Pa) with good flow uniformity (at 1000 sccm). Thermal transport simulations indicate that temperatures up to 1000 °C are expected at the highest TPE fluxes.

  3. In Vitro Skin Permeation Enhancement of Sumatriptan by Microneedle Application.

    Science.gov (United States)

    Nalluri, Buchi N; Anusha, Sai Sri V; Bramhini, Sri R; Amulya, J; Sultana, Ashraf S K; Teja, Chandra U; Das, Diganta B

    2015-01-01

    Different dimensions of commercially available microneedle devices, namely, Admin- Patch(®) microneedle arrays (MN) (0.6, 0.9, 1.2 and 1.5 mm lengths) and Dermaroller(®) microneedle rollers (DR) (0.5 and 1mm lengths) were evaluated for their relative efficiency in enhancement of transdermal permeation of Sumatriptan (SMT). Solubility assessment of SMT was carried out using propylene glycol (PG), polyethylene glycol (PEG) in combination with saline (S) at different ratios and the order of solubility was found to be 70:30 > 80:20 > 90:10 %v/v in both PG:S and PEG:S. In vitro skin permeation studies were performed using PG:S (70:30 %v/v) as donor vehicle. A significant increase in cumulative amount of SMT permeated, steady state flux, permeability coefficient and diffusion coefficient values were observed after microneedle treatment, and the values were in the order of 1.5mm MN >1.2mm MN >0.9mm MN >1mm DR >0.6mm MN >0.5mm DR > passive permeation. Lag times were significantly shorter after longer microneedle application (0.24h for 1.5mm MN). Arrays were found to be superior to rollers with similar microneedle lengths in enhancing SMT permeation and may be attributed to higher density of microneedles and force of application onto skin. The in vitro flux values revealed that 2.5cm(2) area patch is sufficient for effective therapy after treatment of skin with 1.5mm MN. It may be inferred that microneedle application significantly enhances the transdermal penetration of SMT and that it may be feasible to deliver clinically relevant therapeutic levels of SMT using microneedle assisted transdermal delivery systems.

  4. Development of a plasma driven permeation experiment for TPE

    International Nuclear Information System (INIS)

    Buchenauer, Dean; Kolasinski, Robert; Shimada, Masa; Donovan, David; Youchison, Dennis; Merrill, Brad

    2014-01-01

    Highlights: • We have designed and fabricated a novel tritium permeation membrane holder for use in the Tritium Plasma Experiment (TPE). • The membrane temperature is controlled by varying the cooling flow rate and proximity of a spiral cooling channel. • Sealing tests have demonstrated adequate helium leak rates up to temperatures of 1000 °C. • Flow modeling indicates a minimal helium pressure drop across the membrane holder (<700 Pa). • Thermal modeling shows good heat removal and minimal membrane temperature variation (±2%) even up to peak TPE ion fluxes. - Abstract: Experiments on retention of hydrogen isotopes (including tritium) at temperatures less than 800 °C have been carried out in the Tritium Plasma Experiment (TPE) at Idaho National Laboratory [1,2]. To provide a direct measurement of plasma driven permeation in plasma facing materials at temperatures reaching 1000 °C, a new TPE membrane holder has been built to hold test specimens (≤1 mm in thickness) at high temperature while measuring tritium permeating through the membrane from the plasma facing side. This measurement is accomplished by employing a carrier gas that transports the permeating tritium from the backside of the membrane to ion chambers giving a direct measurement of the plasma driven tritium permeation rate. Isolation of the membrane cooling and sweep gases from TPE's vacuum chamber has been demonstrated by sealing tests performed up to 1000 °C of a membrane holder design that provides easy change out of membrane specimens between tests. Simulations of the helium carrier gas which transports tritium to the ion chamber indicate a very small pressure drop (∼700 Pa) with good flow uniformity (at 1000 sccm). Thermal transport simulations indicate that temperatures up to 1000 °C are expected at the highest TPE fluxes

  5. A brief introduction to continuous evolutionary optimization

    CERN Document Server

    Kramer, Oliver

    2014-01-01

    Practical optimization problems are often hard to solve, in particular when they are black boxes and no further information about the problem is available except via function evaluations. This work introduces a collection of heuristics and algorithms for black box optimization with evolutionary algorithms in continuous solution spaces. The book gives an introduction to evolution strategies and parameter control. Heuristic extensions are presented that allow optimization in constrained, multimodal, and multi-objective solution spaces. An adaptive penalty function is introduced for constrained optimization. Meta-models reduce the number of fitness and constraint function calls in expensive optimization problems. The hybridization of evolution strategies with local search allows fast optimization in solution spaces with many local optima. A selection operator based on reference lines in objective space is introduced to optimize multiple conflictive objectives. Evolutionary search is employed for learning kernel ...

  6. Towards a unified model of passive drug permeation I: origins of the unstirred water layer with applications to ionic permeation.

    Science.gov (United States)

    Ghosh, Avijit; Scott, Dennis O; Maurer, Tristan S

    2014-02-14

    In this work, we provide a unified theoretical framework describing how drug molecules can permeate across membranes in neutral and ionized forms for unstirred in vitro systems. The analysis provides a self-consistent basis for the origin of the unstirred water layer (UWL) within the Nernst-Planck framework in the fully unstirred limit and further provides an accounting mechanism based simply on the bulk aqueous solvent diffusion constant of the drug molecule. Our framework makes no new assumptions about the underlying physics of molecular permeation. We hold simply that Nernst-Planck is a reasonable approximation at low concentrations and all physical systems must conserve mass. The applicability of the derived framework has been examined both with respect to the effect of stirring and externally applied voltages to measured permeability. The analysis contains data for 9 compounds extracted from the literature representing a range of permeabilities and aqueous diffusion coefficients. Applicability with respect to ionized permeation is examined using literature data for the permanently charged cation, crystal violet, providing a basis for the underlying mechanism for ionized drug permeation for this molecule as being due to mobile counter-current flow. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Computational investigation of the effects of barrier layers on the permeation of hydrogen through metals

    International Nuclear Information System (INIS)

    Perkins, W.G.

    1975-01-01

    Results of a computational investigation of the permeation behavior of oxide-coated metal membranes are presented. A steady-state permeation model was developed which promises to be useful in evaluation of oxide layers on metals as hydrogen permeation barriers. The pressure and thickness dependence of steady state permeation through oxide-coated metal membranes is described using plots of logarithmic functions. (U.S.)

  8. Measurement of Skin Permeation/Penetration of Nanoparticles for Their Safety Evaluation

    OpenAIRE

    木村, 恵理子; 河野, 雄一郎; 藤堂, 浩明; 五十嵐, 良明; 杉林, 堅次

    2012-01-01

    The aim of the present study was to quantitatively evaluate the skin permeation/penetration of nanomaterials and to consider their penetration pathway through skin. Firstly, penetration/permeation of a model fluorescent nanoparticle, Fluoresbrite?, was determined through intact rat skin and several damaged skins. Fluoresbrite? permeated through only needle-punctured skin. The permeation profiles of soluble high molecular compounds, fluorescein isothiocyanate-dextrans (FITC-dextrans, FDs), wit...

  9. Proteomics in evolutionary ecology.

    Science.gov (United States)

    Baer, B; Millar, A H

    2016-03-01

    Evolutionary ecologists are traditionally gene-focused, as genes propagate phenotypic traits across generations and mutations and recombination in the DNA generate genetic diversity required for evolutionary processes. As a consequence, the inheritance of changed DNA provides a molecular explanation for the functional changes associated with natural selection. A direct focus on proteins on the other hand, the actual molecular agents responsible for the expression of a phenotypic trait, receives far less interest from ecologists and evolutionary biologists. This is partially due to the central dogma of molecular biology that appears to define proteins as the 'dead-end of molecular information flow' as well as technical limitations in identifying and studying proteins and their diversity in the field and in many of the more exotic genera often favored in ecological studies. Here we provide an overview of a newly forming field of research that we refer to as 'Evolutionary Proteomics'. We point out that the origins of cellular function are related to the properties of polypeptide and RNA and their interactions with the environment, rather than DNA descent, and that the critical role of horizontal gene transfer in evolution is more about coopting new proteins to impact cellular processes than it is about modifying gene function. Furthermore, post-transcriptional and post-translational processes generate a remarkable diversity of mature proteins from a single gene, and the properties of these mature proteins can also influence inheritance through genetic and perhaps epigenetic mechanisms. The influence of post-transcriptional diversification on evolutionary processes could provide a novel mechanistic underpinning for elements of rapid, directed evolutionary changes and adaptations as observed for a variety of evolutionary processes. Modern state-of the art technologies based on mass spectrometry are now available to identify and quantify peptides, proteins, protein

  10. 40 CFR 1060.521 - How do I test fuel caps for permeation emissions?

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false How do I test fuel caps for permeation... EQUIPMENT Test Procedures § 1060.521 How do I test fuel caps for permeation emissions? If you measure a fuel tank's permeation emissions with a nonpermeable covering in place of the fuel cap under § 1060.520(b)(5...

  11. Counter-diffusion and -permeation of deuterium and hydrogen through metals

    Energy Technology Data Exchange (ETDEWEB)

    Kizu, Kaname; Tanabe,; Tetsuo, [Nagoya Univ. (Japan)

    1998-03-01

    The first experiments for counter-diffusion and -permeation of deuterium and hydrogen through palladium were performed. Deuterium permeation rates against D{sub 2} pressure were measured under the condition where hydrogen permeated to opposite direction by supplying H{sub 2} gas at the permeated side of D{sub 2}. It was found that not a small amount of deuterium was clearly permeated even if the deuterium pressure was much smaller than the hydrogen pressure. Deuterium permeation rate was gradually reduced by increasing the counter H permeation. The deuterium permeation rate under the counter H permeation is well represented by a simple model in which the ratio of the deuterium permeation rates with and without the counter H permeation was proportional to the fractional concentration of deuterium in the bulk. As increasing the hydrogen counter flow, however, the deuterium permeation rate deviates from the model. This means that adsorption (absorption) of D{sub 2} from gas phase is inhibited and surface recombination of deuterium is blocked by hydrogen. (author)

  12. Applying evolutionary anthropology.

    Science.gov (United States)

    Gibson, Mhairi A; Lawson, David W

    2015-01-01

    Evolutionary anthropology provides a powerful theoretical framework for understanding how both current environments and legacies of past selection shape human behavioral diversity. This integrative and pluralistic field, combining ethnographic, demographic, and sociological methods, has provided new insights into the ultimate forces and proximate pathways that guide human adaptation and variation. Here, we present the argument that evolutionary anthropological studies of human behavior also hold great, largely untapped, potential to guide the design, implementation, and evaluation of social and public health policy. Focusing on the key anthropological themes of reproduction, production, and distribution we highlight classic and recent research demonstrating the value of an evolutionary perspective to improving human well-being. The challenge now comes in transforming relevance into action and, for that, evolutionary behavioral anthropologists will need to forge deeper connections with other applied social scientists and policy-makers. We are hopeful that these developments are underway and that, with the current tide of enthusiasm for evidence-based approaches to policy, evolutionary anthropology is well positioned to make a strong contribution. © 2015 Wiley Periodicals, Inc.

  13. Applying Evolutionary Anthropology

    Science.gov (United States)

    Gibson, Mhairi A; Lawson, David W

    2015-01-01

    Evolutionary anthropology provides a powerful theoretical framework for understanding how both current environments and legacies of past selection shape human behavioral diversity. This integrative and pluralistic field, combining ethnographic, demographic, and sociological methods, has provided new insights into the ultimate forces and proximate pathways that guide human adaptation and variation. Here, we present the argument that evolutionary anthropological studies of human behavior also hold great, largely untapped, potential to guide the design, implementation, and evaluation of social and public health policy. Focusing on the key anthropological themes of reproduction, production, and distribution we highlight classic and recent research demonstrating the value of an evolutionary perspective to improving human well-being. The challenge now comes in transforming relevance into action and, for that, evolutionary behavioral anthropologists will need to forge deeper connections with other applied social scientists and policy-makers. We are hopeful that these developments are underway and that, with the current tide of enthusiasm for evidence-based approaches to policy, evolutionary anthropology is well positioned to make a strong contribution. PMID:25684561

  14. Evolutionary optimization of rotational population transfer

    Energy Technology Data Exchange (ETDEWEB)

    Rouzee, Arnaud; Vrakking, Marc J. J. [FOM Institute for Atomic and Molecular Physics (AMOLF), Science Park 104, NL-1098 XG Amsterdam (Netherlands); Max Born Institut, Max Born Strasse 2A, D-12489, Berlin (Germany); Ghafur, Omair; Gijsbertsen, Arjan [FOM Institute for Atomic and Molecular Physics (AMOLF), Science Park 104, NL-1098 XG Amsterdam (Netherlands); Vidma, Konstantin; Meijer, Afric; Zande, Wim J. van der; Parker, David [Institute of Molecules and Materials, Radboud University Nijmegen, Toernooiveld 1, NL-6500 GL Nijmegen (Netherlands); Shir, Ofer M.; Baeck, Thomas [Leiden Institute of Advanced Computer Science (LIACS), Niels Bohrweg 1, NL-2333 CA Leiden (Netherlands)

    2011-09-15

    We present experimental and numerical studies on control of rotational population transfer of NO(J=1/2) molecules to higher rotational states. We are able to transfer 57% of the population to the J=5/2 state and 46% to J=9/2, in good agreement with quantum mechanical simulations. The optimal pulse shapes are composed of pulse sequences with delays corresponding to the beat frequencies of states on the rotational ladder. The evolutionary algorithm is limited by experimental constraints such as volume averaging and the finite laser intensity used, the latter to circumvent ionization. Without these constraints, near-perfect control (>98%) is possible. In addition, we show that downward control, moving molecules from high to low rotational states, is also possible.

  15. Evolutionary optimization of rotational population transfer

    International Nuclear Information System (INIS)

    Rouzee, Arnaud; Vrakking, Marc J. J.; Ghafur, Omair; Gijsbertsen, Arjan; Vidma, Konstantin; Meijer, Afric; Zande, Wim J. van der; Parker, David; Shir, Ofer M.; Baeck, Thomas

    2011-01-01

    We present experimental and numerical studies on control of rotational population transfer of NO(J=1/2) molecules to higher rotational states. We are able to transfer 57% of the population to the J=5/2 state and 46% to J=9/2, in good agreement with quantum mechanical simulations. The optimal pulse shapes are composed of pulse sequences with delays corresponding to the beat frequencies of states on the rotational ladder. The evolutionary algorithm is limited by experimental constraints such as volume averaging and the finite laser intensity used, the latter to circumvent ionization. Without these constraints, near-perfect control (>98%) is possible. In addition, we show that downward control, moving molecules from high to low rotational states, is also possible.

  16. Archaeogenetics in evolutionary medicine.

    Science.gov (United States)

    Bouwman, Abigail; Rühli, Frank

    2016-09-01

    Archaeogenetics is the study of exploration of ancient DNA (aDNA) of more than 70 years old. It is an important part of the wider studies of many different areas of our past, including animal, plant and pathogen evolution and domestication events. Hereby, we address specifically the impact of research in archaeogenetics in the broader field of evolutionary medicine. Studies on ancient hominid genomes help to understand even modern health patterns. Human genetic microevolution, e.g. related to abilities of post-weaning milk consumption, and specifically genetic adaptation in disease susceptibility, e.g. towards malaria and other infectious diseases, are of the upmost importance in contributions of archeogenetics on the evolutionary understanding of human health and disease. With the increase in both the understanding of modern medical genetics and the ability to deep sequence ancient genetic information, the field of archaeogenetic evolutionary medicine is blossoming.

  17. Part E: Evolutionary Computation

    DEFF Research Database (Denmark)

    2015-01-01

    of Computational Intelligence. First, comprehensive surveys of genetic algorithms, genetic programming, evolution strategies, parallel evolutionary algorithms are presented, which are readable and constructive so that a large audience might find them useful and – to some extent – ready to use. Some more general...... kinds of evolutionary algorithms, have been prudently analyzed. This analysis was followed by a thorough analysis of various issues involved in stochastic local search algorithms. An interesting survey of various technological and industrial applications in mechanical engineering and design has been...... topics like the estimation of distribution algorithms, indicator-based selection, etc., are also discussed. An important problem, from a theoretical and practical point of view, of learning classifier systems is presented in depth. Multiobjective evolutionary algorithms, which constitute one of the most...

  18. Constraint theory, singular lagrangians and multitemporal dynamics

    International Nuclear Information System (INIS)

    Lusanna, L.

    1988-01-01

    Singular Lagrangians and constraint theory permeate theoretical physics, as shown by the relevance of gauge theories, string models and general relativity. Their study used finite---dimensional models as a guide to develop the theory, but their main use was in classical field theory, due to the necessity of understanding their quantization. The covariant quantization of singular Lagrangians led to the BRST approach and to the theory of the effective action. On the other hand their phase---space formulation, culminated with the BFV approach for first class, second class and reducible constraints. It, in turn, gave new insights in the theory of singular Lagrangians and constraints and in their cohomological aspects. However the Hamiltonian approach to field theory is highly nontrivial, is open to criticism due to its problems with locality, geometry and manifest covariance and its canonical quantization has still to be developed, because there is no proof of the renormalizability of the Schroedinger representation of field theory. This paper discusses how, notwithstanding these developments, there is still a big amount of ambiguity at every level of the theory

  19. Evolutionary Statistical Procedures

    CERN Document Server

    Baragona, Roberto; Poli, Irene

    2011-01-01

    This proposed text appears to be a good introduction to evolutionary computation for use in applied statistics research. The authors draw from a vast base of knowledge about the current literature in both the design of evolutionary algorithms and statistical techniques. Modern statistical research is on the threshold of solving increasingly complex problems in high dimensions, and the generalization of its methodology to parameters whose estimators do not follow mathematically simple distributions is underway. Many of these challenges involve optimizing functions for which analytic solutions a

  20. Study on low temperature plasma driven permeation of hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Takizawa, Masayuki [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-03-01

    It is one of the most important problem in PWI of fusion devices from the point of view of tritium leakage that hydrogen diffuses in the wall of the device and permeates through it, which results in hydrogen being released to the coolant side. In this study, plasma driven permeation experiments were carried out with several kinds of metal membranes in the low temperature plasma where ionic and atomic hydrogen as well as electron existed in order to survey PDP mechanism from the many view points. In addition, incident flux rate from the plasma to the membrane surface was evaluated by calculation analysis. As a result the mechanism of low temperature PDP was found out and described as PDP models. The simulation of the membrane pump system was executed and the system performance was estimated with the models. (author). 135 refs.

  1. Gas Permeation Characteristics across Nano-Porous Inorganic Membranes

    Directory of Open Access Journals (Sweden)

    M.R Othman, H. Mukhtar

    2012-10-01

    Full Text Available An overview of parameters affecting gas permeation in inorganic membranes is presented. These factors include membrane physical characteristics, operational parameters and gas molecular characteristics. The membrane physical characteristics include membrane materials and surface area, porosity, pore size and pore size distribution and membrane morphology. The operational parameters include feed flow rate and concentration, stage cut, temperature and pressure. The gas molecular characteristics include gas molecular weight, diameter, critical temperature, critical pressure, Lennard-Jones parameters and diffusion volumes. The current techniques of material characterization may require complementary method in describing microscopic heterogeneity of the porous ceramic media. The method to be incorporated in the future will be to apply a stochastic model and/or fractal dimension. Keywords: Inorganic membrane, surface adsorption, Knudsen diffusion, Micro-porous membrane, permeation, gas separation.

  2. Intact penetratin metabolite permeates across Caco-2 monolayers

    DEFF Research Database (Denmark)

    Birch, Ditlev; Christensen, Malene Vinther; Stærk, Dan

    . Previous studies have demonstrated that cell-penetrating peptides (CPPs) may be used as carriers in order to improve the bioavailability of a therapeutic cargo like insulin after oral administration. Penetratin, a commonly used CPP, has been shown to increase the uptake of insulin across Caco-2 cell......-2 cells cultured on permeable filter inserts and in cell lysates, respectively. The epithelial permeation of penetratin and the formed metabolites was assessed by using Caco-2 monolayers cultured on permeable filter inserts. Results Preliminary data revealed that at least one specific metabolite...... is formed upon both intracellular and extracellular degradation of penetratin (figure 1A). Following incubation with epithelium for 4 hours, the metabolite permeated the Caco-2 monolayer and the concentration increased approximately 10-fold when compared to a sample collected following 15 minutes...

  3. Study on low temperature plasma driven permeation of hydrogen

    International Nuclear Information System (INIS)

    Takizawa, Masayuki

    1998-03-01

    It is one of the most important problem in PWI of fusion devices from the point of view of tritium leakage that hydrogen diffuses in the wall of the device and permeates through it, which results in hydrogen being released to the coolant side. In this study, plasma driven permeation experiments were carried out with several kinds of metal membranes in the low temperature plasma where ionic and atomic hydrogen as well as electron existed in order to survey PDP mechanism from the many view points. In addition, incident flux rate from the plasma to the membrane surface was evaluated by calculation analysis. As a result the mechanism of low temperature PDP was found out and described as PDP models. The simulation of the membrane pump system was executed and the system performance was estimated with the models. (author). 135 refs

  4. Tritium breeders and tritium permeation barrier coatings for fusion reactor

    International Nuclear Information System (INIS)

    Yamawaki, Michio; Kawamura, Hiroshi; Tsuchiya, Kunihiko

    2004-01-01

    A state of R and D of tritium breeders and tritium permeation barrier coatings for fusion reactor is explained. A list of candidate for tritium breeders consists of ceramics containing lithium, for examples, Li 2 O, Li 2 TiO 3 , Li 2 ZrO 3 , Li 4 SiO 4 and LiAlO 2 . The characteristics and form are described. The optimum particle size is from 1 to 10 μm. The production technologies of tritium breeders in the world are stated. Characteristics of ceramics with lithium as tritium breeders are compared. TiC, TiN/TiC, Al 2 O 3 and Cr 2 O 3 -SiO 2 -P 2 O 5 are tritium permeation barrier coating materials. These production methods and evaluation of characteristics are explained. (S.Y.)

  5. Structural and functional significance of water permeation through cotransporters

    DEFF Research Database (Denmark)

    Zeuthen, Thomas; Gorraitz, Edurne; Her, Ka

    2016-01-01

    Membrane transporters, in addition to their major role as specific carriers for ions and small molecules, can also behave as water channels. However, neither the location of the water pathway in the protein nor their functional importance is known. Here, we map the pathway for water and urea...... through the intestinal sodium/glucose cotransporter SGLT1. Molecular dynamics simulations using the atomic structure of the bacterial transporter vSGLT suggest that water permeates the same path as Na+ and sugar. On a structural model of SGLT1, based on the homology structure of vSGLT, we identified...... to be due to alterations in steric hindrance to water and urea, and/or changes in protein folding caused by mismatching of side chains in the water pathway. Water permeation through SGLT1 and other transporters bears directly on the structural mechanism for the transport of polar solutes through...

  6. Permeation barrier properties of thin oxide films on flexible polymer substrates

    International Nuclear Information System (INIS)

    Fahlteich, John; Fahland, Matthias; Schoenberger, Waldemar; Schiller, Nicolas

    2009-01-01

    Solar cells and organic electronic devices require an encapsulation to ensure sufficient lifetime. Key parameters of the encapsulation are permeation barrier, UV stability, temperature stability, optical transmission spectra and mechanical stability. The requirements depend very much on the specific application. Many work groups suggest multilayer stacks to meet the permeation requirements. In this paper the permeation barrier properties of the different constituents of such a multilayer stack are characterized. Different layer materials are compared regarding their water vapour and oxygen permeability as well as the influence of process parameters is examined. Finally temperature dependent permeation measurements are used to characterize the permeation mechanisms in the different constituents of the multilayer barrier

  7. Low-Volatility Agent Permeation (LVAP) Verification and Validation Report

    Science.gov (United States)

    2015-05-01

    custody procedures were obtained from the ISO / IEC 17025 :2005 standard13 as well as the current version of Permeation and Analytical Solutions Branch...Testing and Calibration Laboratories; ISO / IEC 17025 :2005; International Organization for Standardization: Geneva, Switzerland, 2005. 14. Box, G.E...ECBC, as detailed in Section 6.4.4 The International Organization for Standardization ( ISO ) method, 5725-3 (1994), was used to calculate the standard

  8. Assessment of permeation quality of concrete through mercury intrusion porosimetry

    International Nuclear Information System (INIS)

    Kumar, Rakesh; Bhattacharjee, B.

    2004-01-01

    Permeation quality of laboratory cast concrete beams was determined through initial surface absorption test (ISAT). The pore system characteristics of the same concrete beam specimens were determined through mercury intrusion porosimetry (MIP). Data so obtained on the measured initial surface absorption rate of water by concrete and characteristics of pore system of concrete estimated from porosimetry results were used to develop correlations between them. Through these correlations, potential of MIP in assessing the durability quality of concrete in actual structure is demonstrated

  9. Gas Permeation Processes in Biogas Upgrading: A Short Review

    Czech Academy of Sciences Publication Activity Database

    Kárászová, Magda; Sedláková, Zuzana; Izák, Pavel

    2015-01-01

    Roč. 69, č. 10 (2015), s. 1277-1283 ISSN 0366-6352 R&D Projects: GA MŠk(CZ) LD14094; GA MŠk LH14006; GA ČR GA14-12695S Institutional support: RVO:67985858 Keywords : biogas upgrading * memranes * gas permeation Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.326, year: 2015

  10. Hydrogen diffusion, dissolution and permeation of nonmetallic solids

    International Nuclear Information System (INIS)

    Elleman, T.S.; Rao, D.; Verghese, K.; Zumwalt, L.

    1979-01-01

    A review of hydrogen diffusion, dissolution and permeation in metal oxides, carbides, nitrides, halides and hydrides is presented. Results are organized by compound and an effort has been made to resolve differences between measured results where wide disparities exist. The document has been prepared to provide needed data for the development of fusion reactor blankets but the results should be generally useful in technologies that involve interactions between hydrogen and non-metals

  11. Tritium inventory and permeation in liquid breeder blankets

    International Nuclear Information System (INIS)

    Reiter, F.

    1990-01-01

    This report reviews studies of the transport of hydrogen isotopes in the DEMO relevant water-cooled Pb-17Li blanket to be tested in NET and in a self-cooled blanket which uses Pb-17Li or Flibe as a liquid breeder material and V or Fe as a first wall material. The time dependences of tritium inventory and permeation in these blankets and of deuterium and tritium recycling in the self-cooled blanket are presented and discussed

  12. EVOLUTIONARY FOUNDATIONS FOR MOLECULAR MEDICINE

    Science.gov (United States)

    Nesse, Randolph M.; Ganten, Detlev; Gregory, T. Ryan; Omenn, Gilbert S.

    2015-01-01

    Evolution has long provided a foundation for population genetics, but many major advances in evolutionary biology from the 20th century are only now being applied in molecular medicine. They include the distinction between proximate and evolutionary explanations, kin selection, evolutionary models for cooperation, and new strategies for tracing phylogenies and identifying signals of selection. Recent advances in genomics are further transforming evolutionary biology and creating yet more opportunities for progress at the interface of evolution with genetics, medicine, and public health. This article reviews 15 evolutionary principles and their applications in molecular medicine in hopes that readers will use them and others to speed the development of evolutionary molecular medicine. PMID:22544168

  13. A novel lipid nanoemulsion system for improved permeation of granisetron.

    Science.gov (United States)

    Doh, Hea-Jeong; Jung, Yunjin; Balakrishnan, Prabagar; Cho, Hyun-Jong; Kim, Dae-Duk

    2013-01-01

    A new lipid nanoemulsion (LNE) system containing granisetron (GRN) was developed and its in vitro permeation-enhancing effect was evaluated using Caco-2 cell monolayers. Particle size, polydispersity index (PI) and stability of the prepared GRN-loaded LNE systems were also characterized. The mean diameters of prepared LNEs were around 50 nm with PI<0.2. Developed LNEs were stable at 4°C in the dark place over a period of 12 weeks. In vitro drug dissolution and cytotoxicity studies of GRN-loaded LNEs were performed. GRN-loaded LNEs exhibited significantly higher drug dissolution than GRN suspension at pH 6.8 for 2h (P<0.05). In vitro permeation study in Caco-2 cell monolayers showed that the LNEs significantly enhanced the drug permeation compared to GRN powder. The in vivo toxicity study in the rat jejunum revealed that the prepared GRN-loaded LNE was as safe as the commercial formulation (Kytril). These results suggest that LNE could be used as a potential oral liquid formulation of GRN for anti-emetic treatment on the post-operative and chemotherapeutic patients. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Skin penetration and tissue permeation after topical administration of diclofenac.

    Science.gov (United States)

    Hagen, Martina; Baker, Mark

    2017-09-01

    Topical delivery of drugs is an alternative to oral administration, often with similar efficacy but potentially a more favorable tolerability profile. However, topical formulations need to be able to penetrate the skin and permeate to the target areas in quantities sufficient to exert a therapeutic effect. Many factors can affect this process, including the physicochemical properties of the drug, the formulation used, and the site and mode of application. It is believed that measurement of drug concentrations at the sites of action may be an indicator of their likely efficacy. This review addresses these issues, with reference to topically administered diclofenac in osteoarthritis. Articles relevant to this review were identified after a systematic search of Medline and Embase, using the key words "diclofenac", "topical administration" and "osteoarthritis" in the search strategy. The sparse data available indicate that topical diclofenac can penetrate and permeate to deeper tissues, with a lower plasma to tissue ratio than oral diclofenac. The tissue diclofenac levels after topical delivery are sustained over time (at least several hours). However, there is not enough data to establish how diclofenac levels in the joint compare with IC 50 levels (50% of the maximum inhibition of prostaglandin synthesis) established following oral administration. After topical application, diclofenac can penetrate the skin and permeate to deeper tissues, where it reaches a concentration that appears to be sufficient to exert a therapeutic effect. More robust methods are required for in vivo characterization to better estimate the clinical efficacy of topically applied drugs.

  15. Studies on Tasar Cocoon Cooking Using Permeation Method

    Science.gov (United States)

    Javali, Uday C.; Malali, Kiran B.; Ramya, H. G.; Naik, Subhas V.; Padaki, Naveen V.

    2018-02-01

    Cocoon cooking is an important process before reeling of tasar silk yarn. Cooking ensures loosening of the filaments in the tasar cocoons thereby easing the process of yarn withdrawal during reeling process. Tasar cocoons have very hard shell and hence these cocoons need chemical cooking process to loosen the silk filaments. Attempt has been made in this article to study the effect of using vacuum permeation chamber for tasar cocoon cooking in order to reduce the cooking time and improve the quality of tasar silk yarn. Vacuum assisted permeation cooking method has been studied in this article on tasar daba cocoons for cooking efficiency, deflossing and reelability. Its efficiency has been evaluated with respect to different cooking methods viz, traditional and open pan cooking methods. The tasar silk produced after reeling process has been tested for fineness, strength and cohesion properties. Results indicate that permeation method of tasar cooking ensures uniform cooking with higher efficiency along with better reeling performance and improved yarn properties.

  16. Penetration of radionuclides across the skin. Rat age dependent promethium permeation through skin in vitro

    International Nuclear Information System (INIS)

    Kassai, Z.; Kassai, A.; Bauerova, K.; Koprda, V.; Harangozo, M.; Bendova, P.; Bujnova, A.

    2003-01-01

    The composition and the permeation properties of the skin are dependent on age. In the animal models for permation studies, age affects the mechanical as well as the permeation properties significantly. The time dependence of permeation of 147 Pm 3+ from aqueous solution was established by the animal skin model and the age dependence of promethium permeation through the skin was examined. The aim was to find the optimum rat skin age model for radionuclide permeation studies and to assess the relative importance of the main permeation pathways: transepidermal and transfollicular permeation. The skin from 5-day-old rats (5DR) was found to represent the optimum animal model to study transepidermal permeation of ions. The skin from 9-day-old rats (9DR) was selected to study transfollicular permeation of ions. Comparison of the permeated amounts of promethium through the skin without hairs (3 DR to 6 DR) and with hairs (7DR to 12DR) showed that the additional permation mode via follicles significantly contributed to the permeation rate and extent. (author)

  17. Evolutionary trends in Heteroptera

    NARCIS (Netherlands)

    Cobben, R.H.

    1968-01-01

    1. This work, the first volume of a series dealing with evolutionary trends in Heteroptera, is concerned with the egg system of about 400 species. The data are presented systematically in chapters 1 and 2 with a critical review of the literature after each family.

    2. Chapter 3 evaluates facts

  18. Evolutionary mysteries in meiosis

    NARCIS (Netherlands)

    Lenormand, Thomas; Engelstädter, Jan; Johnston, Susan E.; Wijnker, Erik; Haag, Christoph R.

    2016-01-01

    Meiosis is a key event of sexual life cycles in eukaryotes. Its mechanistic details have been uncovered in several model organisms, and most of its essential features have received various and often contradictory evolutionary interpretations. In this perspective, we present an overview of these

  19. Applications of Evolutionary Computation

    NARCIS (Netherlands)

    Mora, Antonio M.; Squillero, Giovanni; Di Chio, C; Agapitos, Alexandros; Cagnoni, Stefano; Cotta, Carlos; Fernández De Vega, F; Di Caro, G A; Drechsler, R.; Ekárt, A; Esparcia-Alcázar, Anna I.; Farooq, M; Langdon, W B; Merelo-Guervós, J.J.; Preuss, M; Richter, O.-M.H.; Silva, Sara; Sim$\\$~oes, A; Squillero, Giovanni; Tarantino, Ernesto; Tettamanzi, Andrea G B; Togelius, J; Urquhart, Neil; Uyar, A S; Yannakakis, G N; Smith, Stephen L; Caserta, Marco; Ramirez, Adriana; Voß, Stefan; Squillero, Giovanni; Burelli, Paolo; Mora, Antonio M.; Squillero, Giovanni; Jan, Mathieu; Matthias, M; Di Chio, C; Agapitos, Alexandros; Cagnoni, Stefano; Cotta, Carlos; Fernández De Vega, F; Di Caro, G A; Drechsler, R.; Ekárt, A; Esparcia-Alcázar, Anna I.; Farooq, M; Langdon, W B; Merelo-Guervós, J.J.; Preuss, M; Richter, O.-M.H.; Silva, Sara; Sim$\\$~oes, A; Squillero, Giovanni; Tarantino, Ernesto; Tettamanzi, Andrea G B; Togelius, J; Urquhart, Neil; Uyar, A S; Yannakakis, G N; Caserta, Marco; Ramirez, Adriana; Voß, Stefan; Squillero, Giovanni; Burelli, Paolo; Esparcia-Alcazar, Anna I; Silva, Sara; Agapitos, Alexandros; Cotta, Carlos; De Falco, Ivanoe; Cioppa, Antonio Della; Diwold, Konrad; Ekart, Aniko; Tarantino, Ernesto; Vega, Francisco Fernandez De; Burelli, Paolo; Sim, Kevin; Cagnoni, Stefano; Simoes, Anabela; Merelo, J.J.; Urquhart, Neil; Haasdijk, Evert; Zhang, Mengjie; Squillero, Giovanni; Eiben, A E; Tettamanzi, Andrea G B; Glette, Kyrre; Rohlfshagen, Philipp; Schaefer, Robert; Caserta, Marco; Ramirez, Adriana; Voß, Stefan

    2015-01-01

    The application of genetic and evolutionary computation to problems in medicine has increased rapidly over the past five years, but there are specific issues and challenges that distinguish it from other real-world applications. Obtaining reliable and coherent patient data, establishing the clinical

  20. Evolutionary perspectives on ageing.

    Science.gov (United States)

    Reichard, Martin

    2017-10-01

    From an evolutionary perspective, ageing is a decrease in fitness with chronological age - expressed by an increase in mortality risk and/or decline in reproductive success and mediated by deterioration of functional performance. While this makes ageing intuitively paradoxical - detrimental to individual fitness - evolutionary theory offers answers as to why ageing has evolved. In this review, I first briefly examine the classic evolutionary theories of ageing and their empirical tests, and highlight recent findings that have advanced our understanding of the evolution of ageing (condition-dependent survival, positive pleiotropy). I then provide an overview of recent theoretical extensions and modifications that accommodate those new discoveries. I discuss the role of indeterminate (asymptotic) growth for lifetime increases in fecundity and ageing trajectories. I outline alternative views that challenge a universal existence of senescence - namely the lack of a germ-soma distinction and the ability of tissue replacement and retrogression to younger developmental stages in modular organisms. I argue that rejuvenation at the organismal level is plausible, but includes a return to a simple developmental stage. This may exempt a particular genotype from somatic defects but, correspondingly, removes any information acquired during development. A resolution of the question of whether a rejuvenated individual is the same entity is central to the recognition of whether current evolutionary theories of ageing, with their extensions and modifications, can explain the patterns of ageing across the Tree of Life. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Editorial overview: Evolutionary psychology

    NARCIS (Netherlands)

    Gangestad, S.W.; Tybur, J.M.

    2016-01-01

    Functional approaches in psychology - which ask what behavior is good for - are almost as old as scientific psychology itself. Yet sophisticated, generative functional theories were not possible until developments in evolutionary biology in the mid-20th century. Arising in the last three decades,

  2. Biochemistry and evolutionary biology

    Indian Academy of Sciences (India)

    Biochemical information has been crucial for the development of evolutionary biology. On the one hand, the sequence information now appearing is producing a huge increase in the amount of data available for phylogenetic analysis; on the other hand, and perhaps more fundamentally, it allows understanding of the ...

  3. Evolutionary Biology Today

    Indian Academy of Sciences (India)

    Hindi and English. Port 1. Resonance, Vo1.7 ... they use. Of course, many evolutionary biologists do work with fossils or DNA, or both, but there are also large numbers of ... The first major division that I like to make is between studies focussed ...

  4. Learning: An Evolutionary Analysis

    Science.gov (United States)

    Swann, Joanna

    2009-01-01

    This paper draws on the philosophy of Karl Popper to present a descriptive evolutionary epistemology that offers philosophical solutions to the following related problems: "What happens when learning takes place?" and "What happens in human learning?" It provides a detailed analysis of how learning takes place without any direct transfer of…

  5. Complex systems, evolutionary planning?

    NARCIS (Netherlands)

    Bertolini, L.; de Roo, G.; Silva, E.A.

    2010-01-01

    Coping with uncertainty is a defining challenge for spatial planners. Accordingly, most spatial planning theories and methods are aimed at reducing uncertainty. However, the question is what should be done when this seems impossible? This chapter proposes an evolutionary interpretation of spatial

  6. Molluscan Evolutionary Development

    DEFF Research Database (Denmark)

    Wanninger, Andreas Wilhelm Georg; Koop, Damien; Moshel-Lynch, Sharon

    2008-01-01

    Brought together by Winston F. Ponder and David R. Lindberg, thirty-six experts on the evolution of the Mollusca provide an up-to-date review of its evolutionary history. The Mollusca are the second largest animal phylum and boast a fossil record of over 540 million years. They exhibit remarkable...

  7. Multi-Objective Constraint Satisfaction for Mobile Robot Area Defense

    Science.gov (United States)

    2010-03-01

    David A. Van Veldhuizen . Evo- lutionary Algorithms for Solving Multi-Objective Problems. Springer, New York, NY, 2nd edition, 2007. [9] Dean, Thomas...J.I. van Hemert, E. Marchiori, and A. G. Steenbeek. “Solving Binary Constraint Satisfaction Problems using Evolutionary Algorithms with an Adaptive

  8. Costs and constraints conspire to produce honest signaling

    DEFF Research Database (Denmark)

    Holman, Luke

    2012-01-01

    that endocrine-mediated trade-offs preclude dishonesty. Several lines of evidence suggest that the realized cost of pheromone production may be nontrivial, and the antagonistic effects of juvenile hormone indicate the presence of significant evolutionary constraints. I conclude that the honesty of queen...

  9. Physics-Based Modeling of Permeation: Simulation of Low-Volatility Agent Permeation and Aerosol Vapor Liquid Assessment Group Experiments

    Science.gov (United States)

    2015-06-01

    methylphosphonothiolate (VX) through natural latex rubber and neoprene resulting from LVAP tests. 2. The permeation model is used to study the sensitivity of...Styrene–Butadiene– Rubber , Ethylene–Propylene–Diene Terpolymer, and Natural Rubber Versus Hydrocarbons (C8–C16). Macromolecules 1991, 24 (9), 2598–2605...22 14. Harogoppad, S.B.; Aminabhavi, T.M. Diffusion and Sorption of Organic Liquids through Polymer Membranes 2. Neoprene, SBR, EPDM, NBR , and

  10. Investigating intertemporal choice through experimental evolutionary robotics.

    Science.gov (United States)

    Paglieri, Fabio; Parisi, Domenico; Patacchiola, Massimiliano; Petrosino, Giancarlo

    2015-06-01

    In intertemporal choices, subjects face a trade-off between value and delay: achieving the most valuable outcome requires a longer time, whereas the immediately available option is objectively poorer. Intertemporal choices are ubiquitous, and comparative studies reveal commonalities and differences across species: all species devalue future rewards as a function of delay (delay aversion), yet there is a lot of inter-specific variance in how rapidly such devaluation occurs. These differences are often interpreted in terms of ecological rationality, as depending on environmental factors (e.g., feeding ecology) and the physiological and morphological constraints of different species (e.g., metabolic rate). Evolutionary hypotheses, however, are hard to verify in vivo, since it is difficult to observe precisely enough real environments, not to mention ancestral ones. In this paper, we discuss the viability of an approach based on evolutionary robotics: in Study 1, we evolve robots without a metabolism in five different ecologies; in Study 2, we evolve metabolic robots (i.e., robots that consume energy over time) in three different ecologies. The intertemporal choices of the robots are analyzed both in their ecology and under laboratory conditions. Results confirm the generality of delay aversion and the usefulness of studying intertemporal choice through experimental evolutionary robotics. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Evolutionary plant physiology: Charles Darwin's forgotten synthesis

    Science.gov (United States)

    Kutschera, Ulrich; Niklas, Karl J.

    2009-11-01

    Charles Darwin dedicated more than 20 years of his life to a variety of investigations on higher plants (angiosperms). It has been implicitly assumed that these studies in the fields of descriptive botany and experimental plant physiology were carried out to corroborate his principle of descent with modification. However, Darwin’s son Francis, who was a professional plant biologist, pointed out that the interests of his father were both of a physiological and an evolutionary nature. In this article, we describe Darwin’s work on the physiology of higher plants from a modern perspective, with reference to the following topics: circumnutations, tropisms and the endogenous oscillator model; the evolutionary patterns of auxin action; the root-brain hypothesis; phloem structure and photosynthesis research; endosymbioses and growth-promoting bacteria; photomorphogenesis and phenotypic plasticity; basal metabolic rate, the Pfeffer-Kleiber relationship and metabolic optimality theory with respect to adaptive evolution; and developmental constraints versus functional equivalence in relationship to directional natural selection. Based on a review of these various fields of inquiry, we deduce the existence of a Darwinian (evolutionary) approach to plant physiology and define this emerging scientific discipline as the experimental study and theoretical analysis of the functions of green, sessile organisms from a phylogenetic perspective.

  12. Evolutionary plant physiology: Charles Darwin's forgotten synthesis.

    Science.gov (United States)

    Kutschera, Ulrich; Niklas, Karl J

    2009-11-01

    Charles Darwin dedicated more than 20 years of his life to a variety of investigations on higher plants (angiosperms). It has been implicitly assumed that these studies in the fields of descriptive botany and experimental plant physiology were carried out to corroborate his principle of descent with modification. However, Darwin's son Francis, who was a professional plant biologist, pointed out that the interests of his father were both of a physiological and an evolutionary nature. In this article, we describe Darwin's work on the physiology of higher plants from a modern perspective, with reference to the following topics: circumnutations, tropisms and the endogenous oscillator model; the evolutionary patterns of auxin action; the root-brain hypothesis; phloem structure and photosynthesis research; endosymbioses and growth-promoting bacteria; photomorphogenesis and phenotypic plasticity; basal metabolic rate, the Pfeffer-Kleiber relationship and metabolic optimality theory with respect to adaptive evolution; and developmental constraints versus functional equivalence in relationship to directional natural selection. Based on a review of these various fields of inquiry, we deduce the existence of a Darwinian (evolutionary) approach to plant physiology and define this emerging scientific discipline as the experimental study and theoretical analysis of the functions of green, sessile organisms from a phylogenetic perspective.

  13. Hidden long evolutionary memory in a model biochemical network

    Science.gov (United States)

    Ali, Md. Zulfikar; Wingreen, Ned S.; Mukhopadhyay, Ranjan

    2018-04-01

    We introduce a minimal model for the evolution of functional protein-interaction networks using a sequence-based mutational algorithm, and apply the model to study neutral drift in networks that yield oscillatory dynamics. Starting with a functional core module, random evolutionary drift increases network complexity even in the absence of specific selective pressures. Surprisingly, we uncover a hidden order in sequence space that gives rise to long-term evolutionary memory, implying strong constraints on network evolution due to the topology of accessible sequence space.

  14. IDEA: Interactive Display for Evolutionary Analyses.

    Science.gov (United States)

    Egan, Amy; Mahurkar, Anup; Crabtree, Jonathan; Badger, Jonathan H; Carlton, Jane M; Silva, Joana C

    2008-12-08

    The availability of complete genomic sequences for hundreds of organisms promises to make obtaining genome-wide estimates of substitution rates, selective constraints and other molecular evolution variables of interest an increasingly important approach to addressing broad evolutionary questions. Two of the programs most widely used for this purpose are codeml and baseml, parts of the PAML (Phylogenetic Analysis by Maximum Likelihood) suite. A significant drawback of these programs is their lack of a graphical user interface, which can limit their user base and considerably reduce their efficiency. We have developed IDEA (Interactive Display for Evolutionary Analyses), an intuitive graphical input and output interface which interacts with PHYLIP for phylogeny reconstruction and with codeml and baseml for molecular evolution analyses. IDEA's graphical input and visualization interfaces eliminate the need to edit and parse text input and output files, reducing the likelihood of errors and improving processing time. Further, its interactive output display gives the user immediate access to results. Finally, IDEA can process data in parallel on a local machine or computing grid, allowing genome-wide analyses to be completed quickly. IDEA provides a graphical user interface that allows the user to follow a codeml or baseml analysis from parameter input through to the exploration of results. Novel options streamline the analysis process, and post-analysis visualization of phylogenies, evolutionary rates and selective constraint along protein sequences simplifies the interpretation of results. The integration of these functions into a single tool eliminates the need for lengthy data handling and parsing, significantly expediting access to global patterns in the data.

  15. IDEA: Interactive Display for Evolutionary Analyses

    Directory of Open Access Journals (Sweden)

    Carlton Jane M

    2008-12-01

    Full Text Available Abstract Background The availability of complete genomic sequences for hundreds of organisms promises to make obtaining genome-wide estimates of substitution rates, selective constraints and other molecular evolution variables of interest an increasingly important approach to addressing broad evolutionary questions. Two of the programs most widely used for this purpose are codeml and baseml, parts of the PAML (Phylogenetic Analysis by Maximum Likelihood suite. A significant drawback of these programs is their lack of a graphical user interface, which can limit their user base and considerably reduce their efficiency. Results We have developed IDEA (Interactive Display for Evolutionary Analyses, an intuitive graphical input and output interface which interacts with PHYLIP for phylogeny reconstruction and with codeml and baseml for molecular evolution analyses. IDEA's graphical input and visualization interfaces eliminate the need to edit and parse text input and output files, reducing the likelihood of errors and improving processing time. Further, its interactive output display gives the user immediate access to results. Finally, IDEA can process data in parallel on a local machine or computing grid, allowing genome-wide analyses to be completed quickly. Conclusion IDEA provides a graphical user interface that allows the user to follow a codeml or baseml analysis from parameter input through to the exploration of results. Novel options streamline the analysis process, and post-analysis visualization of phylogenies, evolutionary rates and selective constraint along protein sequences simplifies the interpretation of results. The integration of these functions into a single tool eliminates the need for lengthy data handling and parsing, significantly expediting access to global patterns in the data.

  16. Constraints, Trade-offs and the Currency of Fitness.

    Science.gov (United States)

    Acerenza, Luis

    2016-03-01

    Understanding evolutionary trajectories remains a difficult task. This is because natural evolutionary processes are simultaneously affected by various types of constraints acting at the different levels of biological organization. Of particular importance are constraints where correlated changes occur in opposite directions, called trade-offs. Here we review and classify the main evolutionary constraints and trade-offs, operating at all levels of trait hierarchy. Special attention is given to life history trade-offs and the conflict between the survival and reproduction components of fitness. Cellular mechanisms underlying fitness trade-offs are described. At the metabolic level, a linear trade-off between growth and flux variability was found, employing bacterial genome-scale metabolic reconstructions. Its analysis indicates that flux variability can be considered as the currency of fitness. This currency is used for fitness transfer between fitness components during adaptations. Finally, a discussion is made regarding the constraints which limit the increase in the amount of fitness currency during evolution, suggesting that occupancy constraints are probably the main restrictions.

  17. Measurement of skin permeation/penetration of nanoparticles for their safety evaluation.

    Science.gov (United States)

    Kimura, Eriko; Kawano, Yuichiro; Todo, Hiroaki; Ikarashi, Yoshiaki; Sugibayashi, Kenji

    2012-01-01

    The aim of the present study was to quantitatively evaluate the skin permeation/penetration of nanomaterials and to consider their penetration pathway through skin. Firstly, penetration/permeation of a model fluorescent nanoparticle, Fluoresbrite®, was determined through intact rat skin and several damaged skins. Fluoresbrite® permeated through only needle-punctured skin. The permeation profiles of soluble high molecular compounds, fluorescein isothiocyanate-dextrans (FITC-dextrans, FDs), with different molecular weights were also measured for comparison. The effects of molecular sizes and different skin pretreatments on the skin barrier were determined on the skin penetration/permeation of Fluoresbrite® and FDs. Fluoresbrite® was not permeated the intact skin, but FDs were permeated the skin. The skin distribution of titanium dioxide and zinc oxide nanoparticles was also observed after topical application of commercial cosmetics. Nanoparticles in sunscreen cosmetics were easily distributed into the groove and hair follicles after their topical application, but seldom migrated from the groove or follicles to viable epidermis and dermis. The obtained results suggested that nanoparticles did not permeate intact skin, but permeated pore-created skin. No or little permeation was observed for these nanomaterials through the stratum corneum.

  18. Financing Constraints and Entrepreneurship

    OpenAIRE

    William R. Kerr; Ramana Nanda

    2009-01-01

    Financing constraints are one of the biggest concerns impacting potential entrepreneurs around the world. Given the important role that entrepreneurship is believed to play in the process of economic growth, alleviating financing constraints for would-be entrepreneurs is also an important goal for policymakers worldwide. We review two major streams of research examining the relevance of financing constraints for entrepreneurship. We then introduce a framework that provides a unified perspecti...

  19. Temporal Concurrent Constraint Programming

    DEFF Research Database (Denmark)

    Nielsen, Mogens; Valencia Posso, Frank Dan

    2002-01-01

    The ntcc calculus is a model of non-deterministic temporal concurrent constraint programming. In this paper we study behavioral notions for this calculus. In the underlying computational model, concurrent constraint processes are executed in discrete time intervals. The behavioral notions studied...... reflect the reactive interactions between concurrent constraint processes and their environment, as well as internal interactions between individual processes. Relationships between the suggested notions are studied, and they are all proved to be decidable for a substantial fragment of the calculus...

  20. Tritium permeation characterization of Al{sub 2}O{sub 3}/FeAl coatings as tritium permeation barriers on 321 type stainless steel containers

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Feilong; Xiang, Xin; Lu, Guangda; Zhang, Guikai, E-mail: zhangguikai@caep.cn; Tang, Tao; Shi, Yan; Wang, Xiaolin

    2016-09-15

    Accurate tritium transport properties of prospective tritium permeation barriers (TPBs) are essential to tritium systems in fusion reactors. By passing a temperature and rate-controlled sweeping gas over specimen surfaces to carry the permeated tritium to an ion chamber, the gas-driven permeation of tritium has been performed on 321 type stainless steel containers with Al{sub 2}O{sub 3}/FeAl barriers, to determine the T-permeation resistant performance and mechanism of the barrier. The tritium permeability of the Al{sub 2}O{sub 3}/FeAl coated container was reduced by 3 orders of magnitude at 500–700 °C by contrast with that of the bare one, which meets the requirement of the tritium permeation reduction factor (PRF) of TPBs for tritium operating components in the CN-HCCB TBM. The Al{sub 2}O{sub 3}/FeAl barrier resists the tritium permeation by the diffusion in the bulk substrate at a limited number of defect sites with an effective area and thickness, suggesting that the TPB quality is a very important factor for efficient T-permeation resistance. - Highlights: • T-permeation has been measured on bare and coated type 321 SS containers. • Al{sub 2}O{sub 3}/FeAl coating give a reduction of T-permeability of 3 orders of magnitude. • Mechanism of Al{sub 2}O{sub 3}/FeAl barrier resisting T-permeation has obtained. • Quality of TPB is a very important factor for efficient T-permeating reduction.

  1. Evolutionary games on graphs

    Science.gov (United States)

    Szabó, György; Fáth, Gábor

    2007-07-01

    Game theory is one of the key paradigms behind many scientific disciplines from biology to behavioral sciences to economics. In its evolutionary form and especially when the interacting agents are linked in a specific social network the underlying solution concepts and methods are very similar to those applied in non-equilibrium statistical physics. This review gives a tutorial-type overview of the field for physicists. The first four sections introduce the necessary background in classical and evolutionary game theory from the basic definitions to the most important results. The fifth section surveys the topological complications implied by non-mean-field-type social network structures in general. The next three sections discuss in detail the dynamic behavior of three prominent classes of models: the Prisoner's Dilemma, the Rock-Scissors-Paper game, and Competing Associations. The major theme of the review is in what sense and how the graph structure of interactions can modify and enrich the picture of long term behavioral patterns emerging in evolutionary games.

  2. Asymmetric Evolutionary Games

    Science.gov (United States)

    McAvoy, Alex; Hauert, Christoph

    2015-01-01

    Evolutionary game theory is a powerful framework for studying evolution in populations of interacting individuals. A common assumption in evolutionary game theory is that interactions are symmetric, which means that the players are distinguished by only their strategies. In nature, however, the microscopic interactions between players are nearly always asymmetric due to environmental effects, differing baseline characteristics, and other possible sources of heterogeneity. To model these phenomena, we introduce into evolutionary game theory two broad classes of asymmetric interactions: ecological and genotypic. Ecological asymmetry results from variation in the environments of the players, while genotypic asymmetry is a consequence of the players having differing baseline genotypes. We develop a theory of these forms of asymmetry for games in structured populations and use the classical social dilemmas, the Prisoner’s Dilemma and the Snowdrift Game, for illustrations. Interestingly, asymmetric games reveal essential differences between models of genetic evolution based on reproduction and models of cultural evolution based on imitation that are not apparent in symmetric games. PMID:26308326

  3. Development of a hydrogen permeation sensor for future tritium applications

    Energy Technology Data Exchange (ETDEWEB)

    Llivina, L.; Colominas, S.; Abellà, J., E-mail: sergi.colominas@iqs.es

    2014-10-15

    Highlights: • Designing and testing of a hydrogen permeation sensor. • Palladium and α-iron have been used as a hydrogen permeation materials in the sensor. • The experiments performed using both membranes showed that the operation of the sensors in the equilibrium mode required at least several hours to reach the hydrogen equilibrium pressure. - Abstract: Tritium monitoring in lithium–lead eutectic is of great importance for the performance of liquid blankets in fusion reactors. In addition, tritium measurements will be required in order to proof tritium self-sufficiency in liquid metal breeding systems. On-line hydrogen (isotopes) sensors must be design and tested in order to accomplish these goals. In this work, an experimental set up was designed in order to test the permeation hydrogen sensors at 500 °C. This experimental set-up allowed working with controlled environments (different hydrogen partial pressures) and the temperature was measured using a thermocouple connected to a temperature controller that regulated an electrical heater. In a first set of experiments, a hydrogen sensor was constructed using an α-iron capsule as an active hydrogen area. The sensor was mounted and tested in the experimental set up. In a second set of experiments the α-iron capsule was replaced by a welded thin palladium disk in order to minimize the death volume. The experiments performed using both membranes (α-iron and palladium) showed that the operation of the sensors in the equilibrium mode required at least several hours to reach the hydrogen equilibrium pressure.

  4. Feasibility of permeation grouting for constructing subsurface barriers

    International Nuclear Information System (INIS)

    Dwyer, B.P.

    1994-04-01

    Efforts are being made to devise technologies that provide interim containment of waste sites while final remediation alternatives are developed. Permeation grouting, a technique used extensively in the civil and mining engineering industry has been investigated as a method for emplacing a subsurface containment barrier beneath existing waste sites. Conceptually an underlying barrier is placed by injecting grout into the formation at less than fracturing pressure from a series of directionally drilled boreholes beneath the waste site. This study evaluated the penetration and performance characteristics in varying soil conditions of four different grout materials (two microfine cements, mineral wax, and sodium silicate) at a field scale. Field testing consisted of grout injection via sleeve (tube-a'-manchette) pipe into both vertical and horizontal borehole configurations at the Mixed Waste Landfill Integrated Demonstration site at Sandia National Laboratories. Prior to, during, and after grout injection non-intrusive geophysical techniques were used to map grout flow. Following the tests, the site was excavated to reveal details of the grout permeation, and grouted soil samples were cored for laboratory characterization. The non-intrusive and intrusive grout mapping showed preferential flow patterns, i.e., the grout tended to follow the path of least resistance. Preliminary testing indicates that permeation grouting is a feasible method for emplacing a low permeability subsurface barrier in the semi-arid unconsolidated alluvial soils common to the Southwest. Despite the success of this project, difficulties in predicting grout flow in heterogeneous soils and non-intrusive methods for imaging grout location and continuity are issues that need more attention

  5. Effect of Microneedle Type on Transdermal Permeation of Rizatriptan.

    Science.gov (United States)

    Uppuluri, Chandrateja; Shaik, Ashraf Sultana; Han, Tao; Nayak, Atul; Nair, Karthik J; Whiteside, Benjamin R; Nalluri, Buchi N; Das, Diganta B

    2017-07-01

    The present study was aimed to investigate the effect of salient microneedle (MN) geometry parameters like length, density, shape and type on transdermal permeation of rizatriptan (RIZ). Studies were carried out using two types of MN devices viz. AdminPatch® arrays (ADM) (0.6, 0.9, 1.2 and 1.5 mm lengths) and laboratory-fabricated polymeric MNs (PMs) of 0.6 mm length. In the case of the PMs, arrays were applied three times at different places within a 1.77-cm 2 skin area (PM-3) to maintain the MN density closer to 0.6 mm ADM. Histological studies revealed that PM, owing to their geometry/design, formed wider and deeper microconduits when compared to ADM of similar length. Approximately 4.9- and 4.2-fold increases in the RIZ steady-state flux values were observed with 1.5 mm ADM and PM-3 applications when compared to the passive studies. A good correlation between different dimensionless parameters like the amount of RIZ permeated (C t /C s ), thickness (h/L) and surface area (S a /L 2 ) of the skin was observed with scaling analyses. Numerical simulations provided further information regarding the distribution of RIZ in MN-treated skin after application of different MNs. Overall, the study suggests that MN application enhances the RIZ transdermal permeation and the geometrical parameters of MNs play an important role in the degree enhancement.

  6. Ionic Selectivity and Permeation Properties of Human PIEZO1 Channels.

    Directory of Open Access Journals (Sweden)

    Radhakrishnan Gnanasambandam

    Full Text Available Members of the eukaryotic PIEZO family (the human orthologs are noted hPIEZO1 and hPIEZO2 form cation-selective mechanically-gated channels. We characterized the selectivity of human PIEZO1 (hPIEZO1 for alkali ions: K+, Na+, Cs+ and Li+; organic cations: TMA and TEA, and divalents: Ba2+, Ca2+, Mg2+ and Mn2+. All monovalent ions permeated the channel. At a membrane potential of -100 mV, Cs+, Na+ and K+ had chord conductances in the range of 35-55 pS with the exception of Li+, which had a significantly lower conductance of ~ 23 pS. The divalents decreased the single-channel permeability of K+, presumably because the divalents permeated slowly and occupied the open channel for a significant fraction of the time. In cell-attached mode, 90 mM extracellular divalents had a conductance for inward currents carried by the divalents of: 25 pS for Ba2+ and 15 pS for Ca2+ at -80 mV and 10 pS for Mg2+ at -50 mV. The organic cations, TMA and TEA, permeated slowly and attenuated K+ currents much like the divalents. As expected, the channel K+ conductance increased with K+ concentration saturating at ~ 45 pS and the KD of K+ for the channel was 32 mM. Pure divalent ion currents were of lower amplitude than those with alkali ions and the channel opening rate was lower in the presence of divalents than in the presence of monovalents. Exposing cells to the actin disrupting reagent cytochalasin D increased the frequency of openings in cell-attached patches probably by reducing mechanoprotection.

  7. Feasibility of permeation grouting for constructing subsurface barriers

    International Nuclear Information System (INIS)

    Dwyer, B.P.

    1994-03-01

    The technical feasibility of emplacing a barrier beneath a waste site using directionally drilled boreholes and permeation grouting was investigated. The benefits of this emplacement system are: (1) Directionally drilled boreholes provide access beneath a waste site without disturbing the waste; (2) interim containment of contaminants allows time for the development of remediation options; (3) in the interim, the volume of waste remains fixed; (4) barriers may enhance the effectiveness of in situ remediation actions; and (5) barrier systems may provide permanent waste containment

  8. Evaluation of a dynamic dissolution/permeation model

    DEFF Research Database (Denmark)

    Sironi, Daniel; Christensen, Mette; Rosenberg, Jörg

    2017-01-01

    -steady state). To this end, a model case was construed: compacts of pure crystalline hydrocortisone methanolate (HC·MeOH) of slow release rates were prepared, and their dissolution and permeation determined simultaneously in a side-by-side setup, separated by a biomimetic barrier (Permeapad...... dissolution rate and flux influenced each other. Interestingly, for all the dynamic scenarios, the incremental flux values obtained correlated nicely with the corresponding actual donor concentrations. Furthermore, donor depletion was tested using a HC solution. The dynamic interplay between decrease in donor...

  9. Extraction of tritium from liquid lithium by permeation

    International Nuclear Information System (INIS)

    Alire, R.M.

    1978-01-01

    This paper assesses a method for extracting tritium from liquid lithium for specific application to the conceptual laser fusion reactor that uses a continuous lithium ''waterfall.'' The tritium diffuses through a refractory metal that contains a getter and is then stored in a hydride-forming alloy. There are various uncertainties with this method including helium-4 extraction, unknown impurities that may accumulate in liquid lithium, the effects of these impurities on tritium separation, and the maintenance of tritium-contaminated equipment. Our study indicates that major tritium losses will occur during equipment maintenance rather than as a result of permeation losses through the primary vessel

  10. Evolutionary design assistants for architecture

    Directory of Open Access Journals (Sweden)

    N. Onur Sönmez

    2015-04-01

    evolutionary decisions. In this way, the Interleaved EA enables the use of different settings and operators for each of the objectives within an overall task, which would be the same for all objectives in a regular multi-objective EA. This property gives the algorithm a modular structure, which offers an improvable method for the utilization of domain-specific knowledge for each sub-task, i.e., objective. The Interleaved EA can be used by Evolutionary Computation (EC researchers and by practitioners who employ EC for their tasks. As a third main output, the “Architectural Stem Cells Framework” is a conceptual framework for architectural design assistants. It proposes a dynamic and multi-layered method for combining a set of design assistants for larger tasks in architectural design. The first component of the framework is a layer-based, parallel task decomposition approach, which aims at obtaining a dynamic parallelization of sub-tasks within a more complicated problem. The second component of the framework is a conception for the development mechanisms for building drafts, i.e., Architectural Stem Cells (ASC. An ASC can be conceived as a semantically marked geometric structure, which contains the information that specifies the possibilities and constraints for how an abstract building may develop from an undetailed stage to a fully developed building draft. ASCs are required for re-integrating the separated task layers of an architectural problem through solution-based development. The ASC Framework brings together many of the ideas of this thesis for a practical research agenda and it is presented to the AD researchers in architecture. Finally, the “design_proxy.layout” (d_p.layout is an architectural layout design assistant based on the design_proxy approach and the IEA. The system uses a relaxed problem definition (producing draft layouts and a flexible layout representation that permits the overlapping of design units and boundaries. User interaction with the

  11. Natural Constraints to Species Diversification.

    Directory of Open Access Journals (Sweden)

    Eric Lewitus

    2016-08-01

    Full Text Available Identifying modes of species diversification is fundamental to our understanding of how biodiversity changes over evolutionary time. Diversification modes are captured in species phylogenies, but characterizing the landscape of diversification has been limited by the analytical tools available for directly comparing phylogenetic trees of groups of organisms. Here, we use a novel, non-parametric approach and 214 family-level phylogenies of vertebrates representing over 500 million years of evolution to identify major diversification modes, to characterize phylogenetic space, and to evaluate the bounds and central tendencies of species diversification. We identify five principal patterns of diversification to which all vertebrate families hold. These patterns, mapped onto multidimensional space, constitute a phylogenetic space with distinct properties. Firstly, phylogenetic space occupies only a portion of all possible tree space, showing family-level phylogenies to be constrained to a limited range of diversification patterns. Secondly, the geometry of phylogenetic space is delimited by quantifiable trade-offs in tree size and the heterogeneity and stem-to-tip distribution of branching events. These trade-offs are indicative of the instability of certain diversification patterns and effectively bound speciation rates (for successful clades within upper and lower limits. Finally, both the constrained range and geometry of phylogenetic space are established by the differential effects of macroevolutionary processes on patterns of diversification. Given these properties, we show that the average path through phylogenetic space over evolutionary time traverses several diversification stages, each of which is defined by a different principal pattern of diversification and directed by a different macroevolutionary process. The identification of universal patterns and natural constraints to diversification provides a foundation for understanding the

  12. Natural Constraints to Species Diversification.

    Science.gov (United States)

    Lewitus, Eric; Morlon, Hélène

    2016-08-01

    Identifying modes of species diversification is fundamental to our understanding of how biodiversity changes over evolutionary time. Diversification modes are captured in species phylogenies, but characterizing the landscape of diversification has been limited by the analytical tools available for directly comparing phylogenetic trees of groups of organisms. Here, we use a novel, non-parametric approach and 214 family-level phylogenies of vertebrates representing over 500 million years of evolution to identify major diversification modes, to characterize phylogenetic space, and to evaluate the bounds and central tendencies of species diversification. We identify five principal patterns of diversification to which all vertebrate families hold. These patterns, mapped onto multidimensional space, constitute a phylogenetic space with distinct properties. Firstly, phylogenetic space occupies only a portion of all possible tree space, showing family-level phylogenies to be constrained to a limited range of diversification patterns. Secondly, the geometry of phylogenetic space is delimited by quantifiable trade-offs in tree size and the heterogeneity and stem-to-tip distribution of branching events. These trade-offs are indicative of the instability of certain diversification patterns and effectively bound speciation rates (for successful clades) within upper and lower limits. Finally, both the constrained range and geometry of phylogenetic space are established by the differential effects of macroevolutionary processes on patterns of diversification. Given these properties, we show that the average path through phylogenetic space over evolutionary time traverses several diversification stages, each of which is defined by a different principal pattern of diversification and directed by a different macroevolutionary process. The identification of universal patterns and natural constraints to diversification provides a foundation for understanding the deep-time evolution of

  13. Natural Constraints to Species Diversification

    Science.gov (United States)

    Lewitus, Eric; Morlon, Hélène

    2016-01-01

    Identifying modes of species diversification is fundamental to our understanding of how biodiversity changes over evolutionary time. Diversification modes are captured in species phylogenies, but characterizing the landscape of diversification has been limited by the analytical tools available for directly comparing phylogenetic trees of groups of organisms. Here, we use a novel, non-parametric approach and 214 family-level phylogenies of vertebrates representing over 500 million years of evolution to identify major diversification modes, to characterize phylogenetic space, and to evaluate the bounds and central tendencies of species diversification. We identify five principal patterns of diversification to which all vertebrate families hold. These patterns, mapped onto multidimensional space, constitute a phylogenetic space with distinct properties. Firstly, phylogenetic space occupies only a portion of all possible tree space, showing family-level phylogenies to be constrained to a limited range of diversification patterns. Secondly, the geometry of phylogenetic space is delimited by quantifiable trade-offs in tree size and the heterogeneity and stem-to-tip distribution of branching events. These trade-offs are indicative of the instability of certain diversification patterns and effectively bound speciation rates (for successful clades) within upper and lower limits. Finally, both the constrained range and geometry of phylogenetic space are established by the differential effects of macroevolutionary processes on patterns of diversification. Given these properties, we show that the average path through phylogenetic space over evolutionary time traverses several diversification stages, each of which is defined by a different principal pattern of diversification and directed by a different macroevolutionary process. The identification of universal patterns and natural constraints to diversification provides a foundation for understanding the deep-time evolution of

  14. Design and tritium permeation analysis of China HCCB TBM port cell

    International Nuclear Information System (INIS)

    Jiangfeng, S.; Guoqiang, H.; Zhiyong, H.; Chang'an, C.; Deli, L.

    2015-01-01

    China is planning to develop a helium-cooled ceramic breeder (HCCB) test blanket module (TBM) on ITER to test key blanket technologies. In this paper, the design and tritium permeation analysis of China HCCB TBM port cell are introduced. A theoretical model has been developed to estimate tritium permeation rates and leak rates from the components and pipes which China has scheduled to house in the port cell. It is shown that on normal working conditions, the permeation and leak rate of the systems in the port cell will be no higher than 1.58 Ci/d without the use of tritium permeation barriers, and 0.10 Ci/d with the use of tritium permeation barriers. It also appears that tritium permeation barriers are necessary for high temperature components such as the reduction bed and the heater

  15. Design and tritium permeation analysis of China HCCB TBM port cell

    Energy Technology Data Exchange (ETDEWEB)

    Jiangfeng, S.; Guoqiang, H.; Zhiyong, H.; Chang' an, C.; Deli, L. [China Academy of Engineering Physics, Mianyang, Sichuan (China)

    2015-03-15

    China is planning to develop a helium-cooled ceramic breeder (HCCB) test blanket module (TBM) on ITER to test key blanket technologies. In this paper, the design and tritium permeation analysis of China HCCB TBM port cell are introduced. A theoretical model has been developed to estimate tritium permeation rates and leak rates from the components and pipes which China has scheduled to house in the port cell. It is shown that on normal working conditions, the permeation and leak rate of the systems in the port cell will be no higher than 1.58 Ci/d without the use of tritium permeation barriers, and 0.10 Ci/d with the use of tritium permeation barriers. It also appears that tritium permeation barriers are necessary for high temperature components such as the reduction bed and the heater.

  16. Temporal Concurrent Constraint Programming

    DEFF Research Database (Denmark)

    Nielsen, Mogens; Palamidessi, Catuscia; Valencia, Frank Dan

    2002-01-01

    The ntcc calculus is a model of non-deterministic temporal concurrent constraint programming. In this paper we study behavioral notions for this calculus. In the underlying computational model, concurrent constraint processes are executed in discrete time intervals. The behavioral notions studied...

  17. Evaluating Distributed Timing Constraints

    DEFF Research Database (Denmark)

    Kristensen, C.H.; Drejer, N.

    1994-01-01

    In this paper we describe a solution to the problem of implementing time-optimal evaluation of timing constraints in distributed real-time systems.......In this paper we describe a solution to the problem of implementing time-optimal evaluation of timing constraints in distributed real-time systems....

  18. Theory of Constraints (TOC)

    DEFF Research Database (Denmark)

    Michelsen, Aage U.

    2004-01-01

    Tankegangen bag Theory of Constraints samt planlægningsprincippet Drum-Buffer-Rope. Endvidere skitse af The Thinking Process.......Tankegangen bag Theory of Constraints samt planlægningsprincippet Drum-Buffer-Rope. Endvidere skitse af The Thinking Process....

  19. Skin permeation and antioxidant efficacy of topically applied resveratrol.

    Science.gov (United States)

    Alonso, Cristina; Martí, M; Barba, C; Carrer, V; Rubio, L; Coderch, L

    2017-08-01

    The permeation of resveratrol was assessed by in vitro and in vivo experiments 24 h after topical administration. The in vitro profile of resveratrol was assessed by Raman spectroscopy. Human skin permeation was analysed in vivo by the tape stripping method with the progressive removal of the stratum corneum layers using adhesive tape strips. Moreover, the free radical scavenging activity of resveratrol after its topical application was determined using the DPPH assay. The Raman spectra indicated that the topically applied resveratrol penetrates deep into the skin. The results showed high amounts of resveratrol in the different stratum corneum layers close to the surface and a constant lower amount in the upper layers of the viable epidermis. The concentration of resveratrol present in the outermost stratum corneum layers was obtained by tape stripping after in vivo application. The results demonstrated that resveratrol mainly remained in the human stratum corneum layers. After topical application, resveratrol maintained its antiradical activity. The antioxidant efficacy of the compound was higher in the inner layers of the stratum corneum. As these results have demonstrated, topically applied resveratrol reinforces the antioxidant system of the stratum corneum and provides an efficient means of increasing the tissue levels of antioxidants in the human epidermis.

  20. Hydrogen permeation through Flinabe fluoride molten salts for blanket candidates

    Energy Technology Data Exchange (ETDEWEB)

    Nishiumi, Ryosuke, E-mail: r.nishiumi@aees.kyushu-u.ac.jp; Fukada, Satoshi; Nakamura, Akira; Katayama, Kazunari

    2016-11-01

    Highlights: • H{sub 2} diffusivity, solubility and permeability in Flinabe as T breeder are determined. • Effects in composition differences among Flibe, Fnabe and Flinabe are compared. • Changes of pressure dependence of Flinabe permeation rate are clarified. - Abstract: Fluoride molten salt Flibe (2LiF + BeF{sub 2}) is a promising candidate for the liquid blanket of a nuclear fusion reactor, because of its large advantages of tritium breeding ratio and heat-transfer fluid. Since its melting point is higher than other liquid candidates, another new fluoride molten salt Flinabe (LiF + NaF + BeF{sub 2}) is recently focused on because of its lower melting point while holding proper breeding properties. In this experiment, hydrogen permeation behavior through the three molten salts of Flibe (2LiF + BeF{sub 2}), Fnabe (NaF + BeF{sub 2}) and Flinabe are investigated in order to clarify the effects of their compositions on hydrogen transfer properties. After making up any of the three molten salts and purifying it using HF, hydrogen permeability, diffusivity and solubility of the molten salts are determined experimentally by using a system composed of tertiary cylindrical tubes. Close agreement is obtained between experimental data and analytical solutions. H{sub 2} permeability, diffusivity and solubility are correlated as a function of temperature and are compared among the three molten salts.

  1. Tritium permeation barrier based on self-healing composite materials

    International Nuclear Information System (INIS)

    Gao Jifeng; Zhang Dan; Suo Jinping

    2010-01-01

    Pores and cracks in ceramic coatings is one of the most important problems to be solved for the thermally sprayed tritium permeation barriers (TPBs) in fusion reactor. In this work, we developed a self-healing composite coating to address this problem. The coating composed of TiC + mixture(TiC/Al 2 O 3 ) + Al 2 O 3 was deposited on martensitic steels by means of atmospheric plasma spraying (APS). Before and after heat treatment, the morphology and phase of the coating were comparatively investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). In the experiment, NiAl + Al 2 O 3 , mixture(TiC/Al 2 O 3 ) + Al 2 O 3 and NiAl + TiC + mixture(TiC/Al 2 O 3 ) + Al 2 O 3 films were also fabricated and studied, respectively. The results showed that the TiC + mixture(TiC/Al 2 O 3 ) + Al 2 O 3 coating exhibited the best self-healing ability and good thermal shock resistance among the four samples after heat treatment under normal atmosphere. The SEM images analyzed by Image Pro software indicated that the porosity of the TiC + mixture(TiC/Al 2 O 3 ) + Al 2 O 3 coating decreased more than 90% in comparison with the sample before heat treatment. This self-healing coating made by thermal spraying might be a good candidate for tritium permeation barrier in fusion reactors.

  2. Effect of helium irradiation on deuterium permeation behavior in tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Uemura, Yuki; Sakurada, Shodai; Fujita, Hiroe; Azuma, Keisuke; Zhou, Quilai [Graduate School of Science & Technology, Shizuoka University, 836 Ohya, Suruga, Shizuoka, 422-8529 Japan (Japan); Hatano, Yuji [Hydrogen Isotope Research Center, University of Toyama, 3190 Gofuku, Toyama, 930-8555 Japan (Japan); Yoshida, Naoaki; Watanabe, Hideo [Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka, 816-8580 Japan (Japan); Oyaizu, Makoto; Isobe, Kanetsugu [National Institutes for Quantum and Radiological Science and Technology, 2166 Obuchi, Rokkasho, Aomori, 039-3212 Japan (Japan); Shimada, Masashi [Idaho National Laboratory, 1955 N. Fremont Avenue, Idaho Falls, ID 83415 (United States); Buchenauer, Dean; Kolasinski, Robert [Sandia National Laboratories, Chemistry, Combustion and Materials Center, Livermore, CA 94550 (United States); Chikada, Takumi [Graduate School of Science & Technology, Shizuoka University, 836 Ohya, Suruga, Shizuoka, 422-8529 Japan (Japan); Oya, Yasuhisa, E-mail: oya.yasuhisa@shizuoka.ac.jp [Graduate School of Science & Technology, Shizuoka University, 836 Ohya, Suruga, Shizuoka, 422-8529 Japan (Japan)

    2017-07-15

    In this study, we measured deuterium (D) gas-driven permeation through tungsten (W) foils that had been pre-damaged by helium ions (He{sup +}). The goal of this work was to determine how ion-induced damage affects hydrogen isotope permeation. At 873 K, the D permeability for W irradiated by 3.0 keV He{sup +} was approximately one order of magnitude lower than that for un-damaged W. This difference diminished with increasing temperature. Even after heating to 1173 K, the permeability returned to less than half of the value measured for un-damaged W. We propose that this is due to nucleation of He bubbles near the surface which potentially serve as a barrier to diffusion deeper into the bulk. Exposure at higher temperatures shows that the D permeability and diffusion coefficients return to levels observed for undamaged material. It is possible that these effects are linked to annealing of defects introduced by ion damage, and whether the defects are stabilized by the presence of trapped He.

  3. Permeation of limonene through disposable nitrile gloves using a dextrous robot hand.

    Science.gov (United States)

    Banaee, Sean; S Que Hee, Shane

    2017-03-28

    The purpose of this study was to investigate the permeation of the low-volatile solvent limonene through different disposable, unlined, unsupported, nitrile exam whole gloves (blue, purple, sterling, and lavender, from Kimberly-Clark). This study utilized a moving and static dextrous robot hand as part of a novel dynamic permeation system that allowed sampling at specific times. Quantitation of limonene in samples was based on capillary gas chromatography-mass spectrometry and the internal standard method (4-bromophenol). The average post-permeation thicknesses (before reconditioning) for all gloves for both the moving and static hand were more than 10% of the pre-permeation ones (P≤0.05), although this was not so on reconditioning. The standardized breakthrough times and steady-state permeation periods were similar for the blue, purple, and sterling gloves. Both methods had similar sensitivity. The lavender glove showed a higher permeation rate (0.490±0.031 μg/cm 2 /min) for the moving robotic hand compared to the non-moving hand (P≤0.05), this being ascribed to a thickness threshold. Permeation parameters for the static and dynamic robot hand models indicate that both methods have similar sensitivity in detecting the analyte during permeation and the blue, purple, and sterling gloves behave similarly during the permeation process whether moving or non-moving.

  4. Permeation of limonene through disposable nitrile gloves using a dextrous robot hand

    Science.gov (United States)

    Banaee, Sean; S Que Hee, Shane

    2017-01-01

    Objectives: The purpose of this study was to investigate the permeation of the low-volatile solvent limonene through different disposable, unlined, unsupported, nitrile exam whole gloves (blue, purple, sterling, and lavender, from Kimberly-Clark). Methods: This study utilized a moving and static dextrous robot hand as part of a novel dynamic permeation system that allowed sampling at specific times. Quantitation of limonene in samples was based on capillary gas chromatography-mass spectrometry and the internal standard method (4-bromophenol). Results: The average post-permeation thicknesses (before reconditioning) for all gloves for both the moving and static hand were more than 10% of the pre-permeation ones (P≤0.05), although this was not so on reconditioning. The standardized breakthrough times and steady-state permeation periods were similar for the blue, purple, and sterling gloves. Both methods had similar sensitivity. The lavender glove showed a higher permeation rate (0.490±0.031 μg/cm2/min) for the moving robotic hand compared to the non-moving hand (P≤0.05), this being ascribed to a thickness threshold. Conclusions: Permeation parameters for the static and dynamic robot hand models indicate that both methods have similar sensitivity in detecting the analyte during permeation and the blue, purple, and sterling gloves behave similarly during the permeation process whether moving or non-moving. PMID:28111415

  5. Development of Novel Formulations to Enhance in Vivo Transdermal Permeation of Tocopherol

    Directory of Open Access Journals (Sweden)

    Nada Aly H.

    2014-09-01

    Full Text Available Tocopherol represents a big challenge for transdermal permeation owing to its extreme hydrophobicity and large molecular mass. The aim of the present study was to develop alpha-tocopherol (T topical formulations and evaluate their ex vivo and in vivo permeation. Franz diffusion cells were used for ex vivo permeation, and neonatal rats were used for in vivo permeation. Seven gel formulations and 21 liquid formulations were investigated for physical stability, viscosity and permeation of T. Analysis of T was performed by a validated HPLC method using a UV detector. The ex vivo permeation from gel and emulsion formulations was very poor (0.001-0.015 %. Highest permeation was observed from monophasic liquid formulations containing dimethyl sulfoxide (DMSO, tocopheryl polyethylene glycols (TPGs, propylene glycol, ethanol and 9.5 % T. The in vivo results demonstrated higher retention in the epidermis compared to subcutaneous tissues, 1377 and 1.13 μg g-1, respectively. Increasing T concentration from 4.8 to 9.5 % did not increase the amount permeated or % of T retained. It was concluded that simple solutions of T in the presence of DMSO and TPGs were more promising systems for effective transdermal permeation compared to gel, emulsion or oleaginous systems.

  6. Studies in evolutionary agroecology

    DEFF Research Database (Denmark)

    Wille, Wibke

    of population performance will increase in frequency. Yield, one of the fundamental agronomic variables, is not an individual, but a population characteristic. A farmer wants a high yield per hectare; he is not interested in the performance of individual plants. When individual selection and population...... of Evolutionary Agroecology that the highest yielding individuals do not necessarily perform best as a population. The investment of resources into strategies and structures increasing individual competitive ability carries a cost. If a whole population consists of individuals investing resources to compete...

  7. Towards Adaptive Evolutionary Architecture

    DEFF Research Database (Denmark)

    Bak, Sebastian HOlt; Rask, Nina; Risi, Sebastian

    2016-01-01

    This paper presents first results from an interdisciplinary project, in which the fields of architecture, philosophy and artificial life are combined to explore possible futures of architecture. Through an interactive evolutionary installation, called EvoCurtain, we investigate aspects of how...... to the development of designs tailored to the individual preferences of inhabitants, changing the roles of architects and designers entirely. Architecture-as-it-could-be is a philosophical approach conducted through artistic methods to anticipate the technological futures of human-centered development within...

  8. Constraint-based reachability

    Directory of Open Access Journals (Sweden)

    Arnaud Gotlieb

    2013-02-01

    Full Text Available Iterative imperative programs can be considered as infinite-state systems computing over possibly unbounded domains. Studying reachability in these systems is challenging as it requires to deal with an infinite number of states with standard backward or forward exploration strategies. An approach that we call Constraint-based reachability, is proposed to address reachability problems by exploring program states using a constraint model of the whole program. The keypoint of the approach is to interpret imperative constructions such as conditionals, loops, array and memory manipulations with the fundamental notion of constraint over a computational domain. By combining constraint filtering and abstraction techniques, Constraint-based reachability is able to solve reachability problems which are usually outside the scope of backward or forward exploration strategies. This paper proposes an interpretation of classical filtering consistencies used in Constraint Programming as abstract domain computations, and shows how this approach can be used to produce a constraint solver that efficiently generates solutions for reachability problems that are unsolvable by other approaches.

  9. Core principles of evolutionary medicine

    Science.gov (United States)

    Grunspan, Daniel Z; Nesse, Randolph M; Barnes, M Elizabeth; Brownell, Sara E

    2018-01-01

    Abstract Background and objectives Evolutionary medicine is a rapidly growing field that uses the principles of evolutionary biology to better understand, prevent and treat disease, and that uses studies of disease to advance basic knowledge in evolutionary biology. Over-arching principles of evolutionary medicine have been described in publications, but our study is the first to systematically elicit core principles from a diverse panel of experts in evolutionary medicine. These principles should be useful to advance recent recommendations made by The Association of American Medical Colleges and the Howard Hughes Medical Institute to make evolutionary thinking a core competency for pre-medical education. Methodology The Delphi method was used to elicit and validate a list of core principles for evolutionary medicine. The study included four surveys administered in sequence to 56 expert panelists. The initial open-ended survey created a list of possible core principles; the three subsequent surveys winnowed the list and assessed the accuracy and importance of each principle. Results Fourteen core principles elicited at least 80% of the panelists to agree or strongly agree that they were important core principles for evolutionary medicine. These principles over-lapped with concepts discussed in other articles discussing key concepts in evolutionary medicine. Conclusions and implications This set of core principles will be helpful for researchers and instructors in evolutionary medicine. We recommend that evolutionary medicine instructors use the list of core principles to construct learning goals. Evolutionary medicine is a young field, so this list of core principles will likely change as the field develops further. PMID:29493660

  10. Practical advantages of evolutionary computation

    Science.gov (United States)

    Fogel, David B.

    1997-10-01

    Evolutionary computation is becoming a common technique for solving difficult, real-world problems in industry, medicine, and defense. This paper reviews some of the practical advantages to using evolutionary algorithms as compared with classic methods of optimization or artificial intelligence. Specific advantages include the flexibility of the procedures, as well as their ability to self-adapt the search for optimum solutions on the fly. As desktop computers increase in speed, the application of evolutionary algorithms will become routine.

  11. Hydrogen gas driven permeation through tungsten deposition layer formed by hydrogen plasma sputtering

    International Nuclear Information System (INIS)

    Uehara, Keiichiro; Katayama, Kazunari; Date, Hiroyuki; Fukada, Satoshi

    2015-01-01

    Highlights: • H permeation tests for W layer formed by H plasma sputtering are performed. • H permeation flux through W layer is larger than that through W bulk. • H diffusivity in W layer is smaller than that in W bulk. • The equilibrium H concentration in W layer is larger than that in W bulk. - Abstract: It is important to evaluate the influence of deposition layers formed on plasma facing wall on tritium permeation and tritium retention in the vessel of a fusion reactor from a viewpoint of safety. In this work, tungsten deposition layers having different thickness and porosity were formed on circular nickel plates by hydrogen RF plasma sputtering. Hydrogen permeation experiment was carried out at the temperature range from 250 °C to 500 °C and at hydrogen pressure range from 1013 Pa to 101,300 Pa. The hydrogen permeation flux through the nickel plate with tungsten deposition layer was significantly smaller than that through a bare nickel plate. This indicates that a rate-controlling step in hydrogen permeation was not permeation through the nickel plate but permeation though the deposition layer. The pressure dependence on the permeation flux differed by temperature. Hydrogen permeation flux through tungsten deposition layer is larger than that through tungsten bulk. From analysis of the permeation curves, it was indicated that hydrogen diffusivity in tungsten deposition layer is smaller than that in tungsten bulk and the equilibrium hydrogen concentration in tungsten deposition layer is enormously larger than that in tungsten bulk at same hydrogen pressure.

  12. Resources, constraints and capabilities

    NARCIS (Netherlands)

    Dhondt, S.; Oeij, P.R.A.; Schröder, A.

    2018-01-01

    Human and financial resources as well as organisational capabilities are needed to overcome the manifold constraints social innovators are facing. To unlock the potential of social innovation for the whole society new (social) innovation friendly environments and new governance structures

  13. Design with Nonlinear Constraints

    KAUST Repository

    Tang, Chengcheng

    2015-01-01

    . The first application is the design of meshes under both geometric and static constraints, including self-supporting polyhedral meshes that are not height fields. Then, with a formulation bridging mesh based and spline based representations, the application

  14. Dynamics and causality constraints

    International Nuclear Information System (INIS)

    Sousa, Manoelito M. de

    2001-04-01

    The physical meaning and the geometrical interpretation of causality implementation in classical field theories are discussed. Causality in field theory are kinematical constraints dynamically implemented via solutions of the field equation, but in a limit of zero-distance from the field sources part of these constraints carries a dynamical content that explains old problems of classical electrodynamics away with deep implications to the nature of physicals interactions. (author)

  15. Momentum constraint relaxation

    International Nuclear Information System (INIS)

    Marronetti, Pedro

    2006-01-01

    Full relativistic simulations in three dimensions invariably develop runaway modes that grow exponentially and are accompanied by violations of the Hamiltonian and momentum constraints. Recently, we introduced a numerical method (Hamiltonian relaxation) that greatly reduces the Hamiltonian constraint violation and helps improve the quality of the numerical model. We present here a method that controls the violation of the momentum constraint. The method is based on the addition of a longitudinal component to the traceless extrinsic curvature A ij -tilde, generated by a vector potential w i , as outlined by York. The components of w i are relaxed to solve approximately the momentum constraint equations, slowly pushing the evolution towards the space of solutions of the constraint equations. We test this method with simulations of binary neutron stars in circular orbits and show that it effectively controls the growth of the aforementioned violations. We also show that a full numerical enforcement of the constraints, as opposed to the gentle correction of the momentum relaxation scheme, results in the development of instabilities that stop the runs shortly

  16. Selection of new constraints

    International Nuclear Information System (INIS)

    Sugier, A.

    2003-01-01

    The selected new constraints should be consistent with the scale of concern i.e. be expressed roughly as fractions or multiples of the average annual background. They should take into account risk considerations and include the values of the currents limits, constraints and other action levels. The recommendation is to select four leading values for the new constraints: 500 mSv ( single event or in a decade) as a maximum value, 0.01 mSv/year as a minimum value; and two intermediate values: 20 mSv/year and 0.3 mSv/year. This new set of dose constraints, representing basic minimum standards of protection for the individuals taking into account the specificity of the exposure situations are thus coherent with the current values which can be found in ICRP Publications. A few warning need however to be noticed: There is no more multi sources limit set by ICRP. The coherence between the proposed value of dose constraint (20 mSv/year) and the current occupational dose limit of 20 mSv/year is valid only if the workers are exposed to one single source. When there is more than one source, it will be necessary to apportion. The value of 1000 mSv lifetimes used for relocation can be expressed into annual dose, which gives approximately 10 mSv/year and is coherent with the proposed dose constraint. (N.C.)

  17. Permeation of chromium salts through human skin in vitro

    DEFF Research Database (Denmark)

    Gammelgaard, Bente; Fullerton, A; Avnstorp, C

    1992-01-01

    Chromium permeation studies were performed on full thickness human skin in diffusion cells. All samples were analysed for the total chromium content by graphite furnace Zeeman-corrected atomic absorption spectrometry. Some samples were analysed by an ion chromatographic method permitting...... the simultaneous determination of Cr(VI) and Cr(III) as well. The amounts of chromium found in all skin layers were significantly higher when potassium dichromate was applied to the skin compared with chromium chloride or chromium nitrate. Chromium could only be detected in the recipient phase after application...... of the dichromate solution. Chromium skin levels increased with increasing concentrations of applied chromium salts up to 0.034 M Cr. The amount of chromium in recipient phase and skin layers increased with increasing pH when the applied solution contained potassium dichromate. This was ascribed to a decreased skin...

  18. Electrostatic tuning of permeation and selectivity in aquaporin water channels

    DEFF Research Database (Denmark)

    Jensen, Mogens O Stibius; Tajkhorshid, E.; Schulten, K.

    2003-01-01

    Water permeation and electrostatic interactions between water and channel are investigated in the Escherichia coli glycerol uptake facilitator GlpF, a member of the aquaporin water channel family, by molecular dynamics simulations. A tetrameric model of the channel embedded in a 16:0/ 18:1c9...... with the protein electrostatic fields enforce a bipolar water configuration inside the channel with dipole inversion at the NPA motifs. At the NPA motifs water-protein electrostatic interactions facilitate this inversion. Furthermore, water-water electrostatic interactions are in all regions inside the channel...... stronger than water-protein interactions, except near a conserved, positively charged Arg residue. We find that variations of the protein electrostatic field through the channel, owing to preserved structural features, completely explain the bipolar orientation of water. This orientation persists despite...

  19. Tritium permeation barrier based on self-healing composite materials

    Energy Technology Data Exchange (ETDEWEB)

    Gao Jifeng; Zhang Dan [State Key Laboratory of Mould Technology, Institute of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Suo Jinping, E-mail: jpsuo@yahoo.com.cn [State Key Laboratory of Mould Technology, Institute of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2010-12-15

    Pores and cracks in ceramic coatings is one of the most important problems to be solved for the thermally sprayed tritium permeation barriers (TPBs) in fusion reactor. In this work, we developed a self-healing composite coating to address this problem. The coating composed of TiC + mixture(TiC/Al{sub 2}O{sub 3}) + Al{sub 2}O{sub 3} was deposited on martensitic steels by means of atmospheric plasma spraying (APS). Before and after heat treatment, the morphology and phase of the coating were comparatively investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). In the experiment, NiAl + Al{sub 2}O{sub 3}, mixture(TiC/Al{sub 2}O{sub 3}) + Al{sub 2}O{sub 3} and NiAl + TiC + mixture(TiC/Al{sub 2}O{sub 3}) + Al{sub 2}O{sub 3} films were also fabricated and studied, respectively. The results showed that the TiC + mixture(TiC/Al{sub 2}O{sub 3}) + Al{sub 2}O{sub 3} coating exhibited the best self-healing ability and good thermal shock resistance among the four samples after heat treatment under normal atmosphere. The SEM images analyzed by Image Pro software indicated that the porosity of the TiC + mixture(TiC/Al{sub 2}O{sub 3}) + Al{sub 2}O{sub 3} coating decreased more than 90% in comparison with the sample before heat treatment. This self-healing coating made by thermal spraying might be a good candidate for tritium permeation barrier in fusion reactors.

  20. Modelling the effect of mixture components on permeation through skin.

    Science.gov (United States)

    Ghafourian, T; Samaras, E G; Brooks, J D; Riviere, J E

    2010-10-15

    A vehicle influences the concentration of penetrant within the membrane, affecting its diffusivity in the skin and rate of transport. Despite the huge amount of effort made for the understanding and modelling of the skin absorption of chemicals, a reliable estimation of the skin penetration potential from formulations remains a challenging objective. In this investigation, quantitative structure-activity relationship (QSAR) was employed to relate the skin permeation of compounds to the chemical properties of the mixture ingredients and the molecular structures of the penetrants. The skin permeability dataset consisted of permeability coefficients of 12 different penetrants each blended in 24 different solvent mixtures measured from finite-dose diffusion cell studies using porcine skin. Stepwise regression analysis resulted in a QSAR employing two penetrant descriptors and one solvent property. The penetrant descriptors were octanol/water partition coefficient, logP and the ninth order path molecular connectivity index, and the solvent property was the difference between boiling and melting points. The negative relationship between skin permeability coefficient and logP was attributed to the fact that most of the drugs in this particular dataset are extremely lipophilic in comparison with the compounds in the common skin permeability datasets used in QSAR. The findings show that compounds formulated in vehicles with small boiling and melting point gaps will be expected to have higher permeation through skin. The QSAR was validated internally, using a leave-many-out procedure, giving a mean absolute error of 0.396. The chemical space of the dataset was compared with that of the known skin permeability datasets and gaps were identified for future skin permeability measurements. Copyright 2010 Elsevier B.V. All rights reserved.

  1. Design, performance and manufacturing analysis for a compact permeator

    Energy Technology Data Exchange (ETDEWEB)

    Sacristan, R., E-mail: mrosa.sacristan@sener.es [SENER Ingenieria y Sistemas, Provenza 392, 5a 08025 Barcelona (Spain); Veredas, G. [EURATOM-CIEMAT Fusion Assoc., BBTU, Av. Complutense 22, 28040, Madrid (Spain); Bonjoch, I. [SENER Ingenieria y Sistemas, Provenza 392, 5a 08025 Barcelona (Spain); Fernandez, I. [EURATOM-CIEMAT Fusion Assoc., BBTU, Av. Complutense 22, 28040, Madrid (Spain); Martin, G. [SENER Ingenieria y Sistemas, Provenza 392, 5a 08025 Barcelona (Spain); Sanmarti, M. [b-FUS, Jardins de les Dones de Negre, 08930 Santa Adria de Besos, Barcelona (Spain); Sedano, L. [EURATOM-CIEMAT Fusion Assoc., BBTU, Av. Complutense 22, 28040, Madrid (Spain)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer Not a single manufacturing option fulfills fully all the requirements that the PAV needs due to complicated manufacturing geometry and materials. Black-Right-Pointing-Pointer To avoid permeation in piping joints is a challenge. Black-Right-Pointing-Pointer CFD sensibility analysis and efficiency analysis show that the aim of the experiment can be accomplished. - Abstract: A fast and efficient recovery of bred tritium is a major milestone of tritium breeding technologies R and D for the demonstration of a fusion reactor tritium self-sufficiency. Permeator against vacuum (PAV) runs as a single-step process for tritium on-line recovery, acts as passive systems allowing to be thermally governed can be easily in-pipe integrated in LiPb loop systems and can be conceived with high compactness. An optimal PAV design is proposed with detailed design parameterization of tritium recovery efficiency at different velocity ranges from numerical simulation based on properly developed Openfoam{sup Registered-Sign} CFD code BelFoam{sup Registered-Sign} customized solver. Diverse structural design options are being considered to manufacture the PAV component that presents diverse manufacturing concerns. Fabrication options are exploring rolling of thin plate with internal armor in the vacuum gap up to the coating of a porous controlled thick wall. The aim of this paper is to emphasize on the advanced performance of the PAV proposed concept, to present and discuss the different technical solutions that have been studied as well as the fabrication tests carried out.

  2. Current Design of the Flange Type Hydrogen Permeation Sensor in Liquid Breeder

    International Nuclear Information System (INIS)

    Lee, E. H.; Jin, H. G.; Yoon, J. S.; Kim, S. K.; Lee, D. W.; Lee, H. G.

    2015-01-01

    In 2004, A. Ciampichetti et al. proposed a hollow capsule shape permeation sensor and they theoretically and experimentally evaluated the performance of the sensor made of Nb membrane at test condition of 500 .deg. C. However, the evaluation result showed the measured hydrogen permeation flux in the sensor much lower than the predicted one and they concluded that, the result is due to the formation of an oxide layer on the sensor membrane surface. Three years later, A. Ciampichetti et al. observed that a hollow capsule shape permeation sensor has too long response time to measure hydrogen concentration in liquid breeder. However, they suggested optimizing the sensor geometry with the reduction of the ratio 'total sensor volume/permeation surface' to overcome the low hydrogen permeating flux. For development of the liquid breeding technologies in nuclear fusion, the permeation sensor to measure tritium concentration in liquid metal breeder has been developed. Lee et al. proposed a flange type permeation sensor to dramatically reduce the ratio sensor 'inside volume/permeation surface' and to remove membrane welding during sensor manufacture process. However, the flange type sensor has problem with sealing. In present study, the modified flange sensor design with a metallic C-ring spring gasket is introduced. The modified sensor will be verified and evaluated under high temperature conditions by end of 2015

  3. Oxygen permeation through oxygen ion oxide-noble metal dual phase composites

    NARCIS (Netherlands)

    Chen, C.S.; Chen, C.S.; Kruidhof, H.; Bouwmeester, Henricus J.M.; Verweij, H.; Burggraaf, Anthonie; Burggraaf, A.J.

    1996-01-01

    Oxygen permeation behaviour of three composites, yttria-stabilized zirconia-palladium, erbia-stabilized bismuth oxidenoble metal (silver, gold) was studied. Oxygen permeation measurements were performed under controlled oxygen pressure gradients at elevated temperatures. Air was supplied at one side

  4. 40 CFR 1060.102 - What permeation emission control requirements apply for fuel lines?

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false What permeation emission control... AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EVAPORATIVE EMISSIONS FROM NEW AND IN-USE NONROAD AND STATIONARY EQUIPMENT Emission Standards and Related Requirements § 1060.102 What permeation...

  5. 40 CFR 1060.103 - What permeation emission control requirements apply for fuel tanks?

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false What permeation emission control... AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EVAPORATIVE EMISSIONS FROM NEW AND IN-USE NONROAD AND STATIONARY EQUIPMENT Emission Standards and Related Requirements § 1060.103 What permeation...

  6. 40 CFR 90.129 - Fuel tank permeation from handheld engines and equipment.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Fuel tank permeation from handheld... KILOWATTS Emission Standards and Certification Provisions § 90.129 Fuel tank permeation from handheld... equipment with respect to fuel tanks. For the purposes of this section, fuel tanks do not include fuel caps...

  7. 40 CFR 1051.515 - How do I test my fuel tank for permeation emissions?

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false How do I test my fuel tank for... Procedures § 1051.515 How do I test my fuel tank for permeation emissions? Measure permeation emissions by weighing a sealed fuel tank before and after a temperature-controlled soak. (a) Preconditioning fuel soak...

  8. 40 CFR 1060.520 - How do I test fuel tanks for permeation emissions?

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false How do I test fuel tanks for... STATIONARY EQUIPMENT Test Procedures § 1060.520 How do I test fuel tanks for permeation emissions? Measure permeation emissions by weighing a sealed fuel tank before and after a temperature-controlled soak. (a...

  9. Modeling benzene permeation through drinking water high density polyethylene (HDPE) pipes.

    Science.gov (United States)

    Mao, Feng; Ong, Say Kee; Gaunt, James A

    2015-09-01

    Organic compounds such as benzene, toluene, ethyl benzene and o-, m-, and p-xylene from contaminated soil and groundwater may permeate through thermoplastic pipes which are used for the conveyance of drinking water in water distribution systems. In this study, permeation parameters of benzene in 25 mm (1 inch) standard inside dimension ratio (SIDR) 9 high density polyethylene (HDPE) pipes were estimated by fitting the measured data to a permeation model based on a combination of equilibrium partitioning and Fick's diffusion. For bulk concentrations between 6.0 and 67.5 mg/L in soil pore water, the concentration-dependent diffusion coefficients of benzene were found to range from 2.0×10(-9) to 2.8×10(-9) cm2/s while the solubility coefficient was determined to be 23.7. The simulated permeation curves of benzene for SIDR 9 and SIDR 7 series of HDPE pipes indicated that small diameter pipes were more vulnerable to permeation of benzene than large diameter pipes, and the breakthrough of benzene into the HDPE pipe was retarded and the corresponding permeation flux decreased with an increase of the pipe thickness. HDPE pipes exposed to an instantaneous plume exhibited distinguishable permeation characteristics from those exposed to a continuous source with a constant input. The properties of aquifer such as dispersion coefficients (DL) also influenced the permeation behavior of benzene through HDPE pipes.

  10. Current Design of the Flange Type Hydrogen Permeation Sensor in Liquid Breeder

    Energy Technology Data Exchange (ETDEWEB)

    Lee, E. H.; Jin, H. G.; Yoon, J. S.; Kim, S. K.; Lee, D. W. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Lee, H. G. [National Fusion Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    In 2004, A. Ciampichetti et al. proposed a hollow capsule shape permeation sensor and they theoretically and experimentally evaluated the performance of the sensor made of Nb membrane at test condition of 500 .deg. C. However, the evaluation result showed the measured hydrogen permeation flux in the sensor much lower than the predicted one and they concluded that, the result is due to the formation of an oxide layer on the sensor membrane surface. Three years later, A. Ciampichetti et al. observed that a hollow capsule shape permeation sensor has too long response time to measure hydrogen concentration in liquid breeder. However, they suggested optimizing the sensor geometry with the reduction of the ratio 'total sensor volume/permeation surface' to overcome the low hydrogen permeating flux. For development of the liquid breeding technologies in nuclear fusion, the permeation sensor to measure tritium concentration in liquid metal breeder has been developed. Lee et al. proposed a flange type permeation sensor to dramatically reduce the ratio sensor 'inside volume/permeation surface' and to remove membrane welding during sensor manufacture process. However, the flange type sensor has problem with sealing. In present study, the modified flange sensor design with a metallic C-ring spring gasket is introduced. The modified sensor will be verified and evaluated under high temperature conditions by end of 2015.

  11. Complexity in Evolutionary Processes

    International Nuclear Information System (INIS)

    Schuster, P.

    2010-01-01

    Darwin's principle of evolution by natural selection is readily casted into a mathematical formalism. Molecular biology revealed the mechanism of mutation and provides the basis for a kinetic theory of evolution that models correct reproduction and mutation as parallel chemical reaction channels. A result of the kinetic theory is the existence of a phase transition in evolution occurring at a critical mutation rate, which represents a localization threshold for the population in sequence space. Occurrence and nature of such phase transitions depend critically on fitness landscapes. The fitness landscape being tantamount to a mapping from sequence or genotype space into phenotype space is identified as the true source of complexity in evolution. Modeling evolution as a stochastic process is discussed and neutrality with respect to selection is shown to provide a major challenge for understanding evolutionary processes (author)

  12. Evolutionary games under incompetence.

    Science.gov (United States)

    Kleshnina, Maria; Filar, Jerzy A; Ejov, Vladimir; McKerral, Jody C

    2018-02-26

    The adaptation process of a species to a new environment is a significant area of study in biology. As part of natural selection, adaptation is a mutation process which improves survival skills and reproductive functions of species. Here, we investigate this process by combining the idea of incompetence with evolutionary game theory. In the sense of evolution, incompetence and training can be interpreted as a special learning process. With focus on the social side of the problem, we analyze the influence of incompetence on behavior of species. We introduce an incompetence parameter into a learning function in a single-population game and analyze its effect on the outcome of the replicator dynamics. Incompetence can change the outcome of the game and its dynamics, indicating its significance within what are inherently imperfect natural systems.

  13. Occult hepatitis B infection: an evolutionary scenario

    Directory of Open Access Journals (Sweden)

    Lukashov Vladimir V

    2008-12-01

    Full Text Available Abstract Background Occult or latent hepatitis B virus (HBV infection is defined as infection with detectable HBV DNA and undetectable surface antigen (HBsAg in patients' blood. The cause of an overt HBV infection becoming an occult one is unknown. To gain insight into the mechanism of the development of occult infection, we compared the full-length HBV genome from a blood donor carrying an occult infection (d4 with global genotype D genomes. Results The phylogenetic analysis of polymerase, core and X protein sequences did not distinguish d4 from other genotype D strains. Yet, d4 surface protein formed the evolutionary outgroup relative to all other genotype D strains. Its evolutionary branch was the only one where accumulation of substitutions suggests positive selection (dN/dS = 1.3787. Many of these substitutiions accumulated specifically in regions encoding the core/surface protein interface, as revealed in a 3D-modeled protein complex. We identified a novel RNA splicing event (deleting nucleotides 2986-202 that abolishes surface protein gene expression without affecting polymerase, core and X-protein related functions. Genotype D strains differ in their ability to perform this 2986-202 splicing. Strains prone to 2986-202 splicing constitute a separate clade in a phylogenetic tree of genotype D HBVs. A single substitution (G173T that is associated with clade membership alters the local RNA secondary structure and is proposed to affect splicing efficiency at the 202 acceptor site. Conclusion We propose an evolutionary scenario for occult HBV infection, in which 2986-202 splicing generates intracellular virus particles devoid of surface protein, which subsequently accumulates mutations due to relaxation of coding constraints. Such viruses are deficient of autonomous propagation and cannot leave the host cell until it is lysed.

  14. Hydrogen permeation inhibition by zinc-nickel alloy plating on steel XC68

    International Nuclear Information System (INIS)

    El Hajjami, A.; Gigandet, M.P.; De Petris-Wery, M.; Catonne, J.C.; Duprat, J.J.; Thiery, L.; Raulin, F.; Starck, B.; Remy, P.

    2008-01-01

    The inhibition of hydrogen permeation and barrier effect by zinc-nickel plating was investigated using the Devanathan-Stachurski permeation technique. The hydrogen permeation and hydrogen diffusion for the zinc-nickel (12-15%) plating on steel XC68 is compared with zinc and nickel. Hydrogen permeation and hydrogen diffusion were followed as functions of time at current density applied (cathodic side) and potential permanent (anodic side). The hydrogen permeation inhibition for zinc-nickel is intermediate to that of nickel and zinc. This inhibition was due to nickel-rich layer effects at the Zn-Ni alloy/substrate interface, is shown by GDOES. Zinc-nickel plating inhibited the hydrogen diffusion greater as compared to zinc. This diffusion resistance was due to the barrier effect caused by the nickel which is present at the interface and transformed the hydrogen atomic to Ni 2 H compound, as shown by GIXRD.

  15. Hydrogen permeation inhibition by zinc-nickel alloy plating on steel XC68

    Energy Technology Data Exchange (ETDEWEB)

    El Hajjami, A. [Institut UTINAM, UMR CNRS 6213, Sonochimie et Reactivite des Surfaces, Universite de Franche-Comte, 16 route de Gray, 25030 Besancon Cedex (France); Coventya S.A.S., 51 rue Pierre, 92588 Clichy Cedex (France); Gigandet, M.P. [Institut UTINAM, UMR CNRS 6213, Sonochimie et Reactivite des Surfaces, Universite de Franche-Comte, 16 route de Gray, 25030 Besancon Cedex (France)], E-mail: marie-pierre.gigandet@univ-fcomte.fr; De Petris-Wery, M. [Institut Universitaire de Technologie d' Orsay, Universite Paris XI, Plateau de Moulon, 91400 Orsay (France); Catonne, J.C. [Professeur Honoraire du Conservatoire national des arts et metiers (CNAM), Paris (France); Duprat, J.J.; Thiery, L.; Raulin, F. [Coventya S.A.S., 51 rue Pierre, 92588 Clichy Cedex (France); Starck, B.; Remy, P. [Lisi Automotive, 28 faubourg de Belfort, BP 19, 90101 Delle Cedex (France)

    2008-12-30

    The inhibition of hydrogen permeation and barrier effect by zinc-nickel plating was investigated using the Devanathan-Stachurski permeation technique. The hydrogen permeation and hydrogen diffusion for the zinc-nickel (12-15%) plating on steel XC68 is compared with zinc and nickel. Hydrogen permeation and hydrogen diffusion were followed as functions of time at current density applied (cathodic side) and potential permanent (anodic side). The hydrogen permeation inhibition for zinc-nickel is intermediate to that of nickel and zinc. This inhibition was due to nickel-rich layer effects at the Zn-Ni alloy/substrate interface, is shown by GDOES. Zinc-nickel plating inhibited the hydrogen diffusion greater as compared to zinc. This diffusion resistance was due to the barrier effect caused by the nickel which is present at the interface and transformed the hydrogen atomic to Ni{sub 2}H compound, as shown by GIXRD.

  16. Modell experiments to determine the effect of inhibitive oxide layers on metals against hydrogen permeation

    International Nuclear Information System (INIS)

    Zink, U.

    1983-11-01

    The coupling of H 2 -permeation and corrosion has been examined with the high-temperature alloys Incoloy 800 and Incoloy 802. Permeationsrates as well as corrosionsrates have been measured simultanously under H 2 O-H 2 atmospheres in the test-facility HD-PERM. Test parameters have been temperature and oxidationpotential. Parabolic laws for the growth of the oxide scales have been identified and are considered to be highly important for the efficiency of a permeation barrier. A comparison between the temperature dependencies of corrosionsrates and H 2 -permeationsrates has revealed that permeation and corrosion are coupled only in so far that the permeation barrier is formed by the corrosion reaction. The corrosion data (parabolic rate constant, activation energy) of the oxide scales have given clear indications for the existence of a Cr 2 O 3 -layer, which is considered to be responsible for efficient oxide permeation barriers. (orig.) [de

  17. Uses and evaluation methods of potential hydrogen permeation barriers for nuclear reactor materials

    International Nuclear Information System (INIS)

    Noga, J.O.; Piercy, G.R.; Bowker, J.T.

    1985-07-01

    This report summarizes results on the use of coatings as hydrogen permeation barriers on nuclear reactor component materials. Two classes of base materials were considered, exothermic hydrogen absorbers and endothermic hydrogen absorbers. The results of the tests indicate that substantial reductions in the amount of hydrogen absorbed by a metal can be achieved through the use of hydrogen permeation barrier coatings. Gold was determined to provide an effective hydrogen permeation barrier on Zr-2-1/2 Nb pressure tube material. Tin was determined to be a suitable hydrogen permeation barrier when applied on AISI 410 stainless steel and iron. Both gas phase and electrochemical permeation techniques were used to determine hydrogen permeabilities through coatings and base materials

  18. Open Issues in Evolutionary Robotics.

    Science.gov (United States)

    Silva, Fernando; Duarte, Miguel; Correia, Luís; Oliveira, Sancho Moura; Christensen, Anders Lyhne

    2016-01-01

    One of the long-term goals in evolutionary robotics is to be able to automatically synthesize controllers for real autonomous robots based only on a task specification. While a number of studies have shown the applicability of evolutionary robotics techniques for the synthesis of behavioral control, researchers have consistently been faced with a number of issues preventing the widespread adoption of evolutionary robotics for engineering purposes. In this article, we review and discuss the open issues in evolutionary robotics. First, we analyze the benefits and challenges of simulation-based evolution and subsequent deployment of controllers versus evolution on real robotic hardware. Second, we discuss specific evolutionary computation issues that have plagued evolutionary robotics: (1) the bootstrap problem, (2) deception, and (3) the role of genomic encoding and genotype-phenotype mapping in the evolution of controllers for complex tasks. Finally, we address the absence of standard research practices in the field. We also discuss promising avenues of research. Our underlying motivation is the reduction of the current gap between evolutionary robotics and mainstream robotics, and the establishment of evolutionary robotics as a canonical approach for the engineering of autonomous robots.

  19. Evolutionary economics and industry location

    NARCIS (Netherlands)

    Boschma, R.A.; Frenken, K.

    2003-01-01

    This paper aims to provide the outlines of an evolutionary economic geography of industry location. We discuss two evolutionary explanations of industry location, that is, one that concentrates on spin-offs, and one that focuses attention on knowledge and agglomeration economies. We claim that both

  20. Contemporary issues in evolutionary biology

    Indian Academy of Sciences (India)

    These discussions included, among others, the possible consequences of nonDNA-based inheritance—epigenetics and cultural evolution, niche construction, and developmental mechanisms on our understanding of the evolutionary process, speciation, complexity in biology, and constructing a formal evolutionary theory.

  1. Contemporary issues in evolutionary biology

    Indian Academy of Sciences (India)

    We are delighted to bring to the readers, a set of peer-reviewed papers on evolutionary biology, published as a special issue of the Journal of Genetics. These papers emanated from ruminations upon and discussions at the Foundations of. Evolutionary Theory: the Ongoing Synthesis meeting at Coorg, India, in February ...

  2. Fixation Time for Evolutionary Graphs

    Science.gov (United States)

    Nie, Pu-Yan; Zhang, Pei-Ai

    Evolutionary graph theory (EGT) is recently proposed by Lieberman et al. in 2005. EGT is successful for explaining biological evolution and some social phenomena. It is extremely important to consider the time of fixation for EGT in many practical problems, including evolutionary theory and the evolution of cooperation. This study characterizes the time to asymptotically reach fixation.

  3. Applications of evolutionary economic geography

    NARCIS (Netherlands)

    Boschma, R.A.; Frenken, K.; Puranam, Krishna Kishore; Ravi Kumar Jain B., xx

    2008-01-01

    This paper is written as the first chapter of an edited volume on evolutionary economics and economic geography (Frenken, K., editor, Applied Evolutionary Economics and Economic Geography, Cheltenham: Edward Elgar, expected publication date February 2007). The paper reviews empirical applications of

  4. Misconceptions and constraints

    International Nuclear Information System (INIS)

    Whitten, M.; Mahon, R.

    2005-01-01

    In theory, the sterile insect technique (SIT) is applicable to a wide variety of invertebrate pests. However, in practice, the approach has been successfully applied to only a few major pests. Chapters in this volume address possible reasons for this discrepancy, e.g. Klassen, Lance and McInnis, and Robinson and Hendrichs. The shortfall between theory and practice is partly due to the persistence of some common misconceptions, but it is mainly due to one constraint, or a combination of constraints, that are biological, financial, social or political in nature. This chapter's goal is to dispel some major misconceptions, and view the constraints as challenges to overcome, seeing them as opportunities to exploit. Some of the common misconceptions include: (1) released insects retain residual radiation, (2) females must be monogamous, (3) released males must be fully sterile, (4) eradication is the only goal, (5) the SIT is too sophisticated for developing countries, and (6) the SIT is not a component of an area-wide integrated pest management (AW-IPM) strategy. The more obvious constraints are the perceived high costs of the SIT, and the low competitiveness of released sterile males. The perceived high up-front costs of the SIT, their visibility, and the lack of private investment (compared with alternative suppression measures) emerge as serious constraints. Failure to appreciate the true nature of genetic approaches, such as the SIT, may pose a significant constraint to the wider adoption of the SIT and other genetically-based tactics, e.g. transgenic genetically modified organisms (GMOs). Lack of support for the necessary underpinning strategic research also appears to be an important constraint. Hence the case for extensive strategic research in ecology, population dynamics, genetics, and insect behaviour and nutrition is a compelling one. Raising the competitiveness of released sterile males remains the major research objective of the SIT. (author)

  5. Evolutionary Explanations of Eating Disorders

    Directory of Open Access Journals (Sweden)

    Igor Kardum

    2008-12-01

    Full Text Available This article reviews several most important evolutionary mechanisms that underlie eating disorders. The first part clarifies evolutionary foundations of mental disorders and various mechanisms leading to their development. In the second part selective pressures and evolved adaptations causing contemporary epidemic of obesity as well as differences in dietary regimes and life-style between modern humans and their ancestors are described. Concerning eating disorders, a number of current evolutionary explanations of anorexia nervosa are presented together with their main weaknesses. Evolutionary explanations of eating disorders based on the reproductive suppression hypothesis and its variants derived from kin selection theory and the model of parental manipulation were elaborated. The sexual competition hypothesis of eating disorder, adapted to flee famine hypothesis as well as explanation based on the concept of social attention holding power and the need to belonging were also explained. The importance of evolutionary theory in modern conceptualization and research of eating disorders is emphasized.

  6. An evolutionary medicine approach to understanding factors that contribute to chronic obstructive pulmonary disease.

    Science.gov (United States)

    Aoshiba, Kazutetsu; Tsuji, Takao; Itoh, Masayuki; Yamaguchi, Kazuhiro; Nakamura, Hiroyuki

    2015-01-01

    Although many studies have been published on the causes and mechanisms of chronic obstructive pulmonary disease (COPD), the reason for the existence of COPD and the reasons why COPD develops in humans have hardly been studied. Evolutionary medical approaches are required to explain not only the proximate factors, such as the causes and mechanisms of a disease, but the ultimate (evolutionary) factors as well, such as why the disease is present and why the disease develops in humans. According to the concepts of evolutionary medicine, disease susceptibility is acquired as a result of natural selection during the evolutionary process of traits linked to the genes involved in disease susceptibility. In this paper, we discuss the following six reasons why COPD develops in humans based on current evolutionary medical theories: (1) evolutionary constraints; (2) mismatch between environmental changes and evolution; (3) co-evolution with pathogenic microorganisms; (4) life history trade-off; (5) defenses and their costs, and (6) reproductive success at the expense of health. Our perspective pursues evolutionary answers to the fundamental question, 'Why are humans susceptible to this common disease, COPD, despite their long evolutionary history?' We believe that the perspectives offered by evolutionary medicine are essential for researchers to better understand the significance of their work.

  7. Whole glove permeation of cyclohexanol through disposable nitrile gloves on a dextrous robot hand: Fist clenching vs. non-clenching.

    Science.gov (United States)

    Mathews, Airek R; Que Hee, Shane S

    2017-04-01

    The differences in permeation parameters when a gloved dextrous robot hand clenched and did not were investigated with the dynamic permeation system described in the companion paper. Increased permeation through the gloves of the present study for cyclohexanol when the gloved hand clenched depended on glove thickness and porosity for cyclohexanol permeation. The Sterling glove, the thinnest and most porous, was the least protective. Hand clenching promoted more permeation for the Sterling glove in terms of breakthrough times, steady state permeation rate, and diffusion coefficient. The Safeskin glove showed increased permeation only for the steady state permeation rate but not breakthrough times or diffusion coefficient. The Blue and Purple gloves showed no differences when the hand was clenching or not. The correlational analysis supported differences between the clenching and non-clenching situations, and the risk assessment considered the worst and best scenarios relative to one and two hydrated hands that were and were not protected by specific gloves.

  8. An Evolutionary Real-Time 3D Route Planner for Aircraft

    Institute of Scientific and Technical Information of China (English)

    郑昌文; 丁明跃; 周成平

    2003-01-01

    A novel evolutionary route planner for aircraft is proposed in this paper. In the new planner, individual candidates are evaluated with respect to the workspace, thus the computation of the configuration space is not required. By using problem-specific chromosome structure and genetic operators, the routes are generated in real time,with different mission constraints such as minimum route leg length and flying altitude, maximum turning angle, maximum climbing/diving angle and route distance constraint taken into account.

  9. Orthology and paralogy constraints: satisfiability and consistency.

    Science.gov (United States)

    Lafond, Manuel; El-Mabrouk, Nadia

    2014-01-01

    A variety of methods based on sequence similarity, reconciliation, synteny or functional characteristics, can be used to infer orthology and paralogy relations between genes of a given gene family  G. But is a given set  C of orthology/paralogy constraints possible, i.e., can they simultaneously co-exist in an evolutionary history for  G? While previous studies have focused on full sets of constraints, here we consider the general case where  C does not necessarily involve a constraint for each pair of genes. The problem is subdivided in two parts: (1) Is  C satisfiable, i.e. can we find an event-labeled gene tree G inducing  C? (2) Is there such a G which is consistent, i.e., such that all displayed triplet phylogenies are included in a species tree? Previous results on the Graph sandwich problem can be used to answer to (1), and we provide polynomial-time algorithms for satisfiability and consistency with a given species tree. We also describe a new polynomial-time algorithm for the case of consistency with an unknown species tree and full knowledge of pairwise orthology/paralogy relationships, as well as a branch-and-bound algorithm in the case when unknown relations are present. We show that our algorithms can be used in combination with ProteinOrtho, a sequence similarity-based orthology detection tool, to extract a set of robust orthology/paralogy relationships.

  10. Occupational dose constraint

    International Nuclear Information System (INIS)

    Heilbron Filho, Paulo Fernando Lavalle; Xavier, Ana Maria

    2005-01-01

    The revision process of the international radiological protection regulations has resulted in the adoption of new concepts, such as practice, intervention, avoidable and restriction of dose (dose constraint). The latter deserving of special mention since it may involve reducing a priori of the dose limits established both for the public and to individuals occupationally exposed, values that can be further reduced, depending on the application of the principle of optimization. This article aims to present, with clarity, from the criteria adopted to define dose constraint values to the public, a methodology to establish the dose constraint values for occupationally exposed individuals, as well as an example of the application of this methodology to the practice of industrial radiography

  11. Psychological constraints on egalitarianism

    DEFF Research Database (Denmark)

    Kasperbauer, Tyler Joshua

    2015-01-01

    processes motivating people to resist various aspects of egalitarianism. I argue for two theses, one normative and one descriptive. The normative thesis holds that egalitarians must take psychological constraints into account when constructing egalitarian ideals. I draw from non-ideal theories in political...... philosophy, which aim to construct moral goals with current social and political constraints in mind, to argue that human psychology must be part of a non-ideal theory of egalitarianism. The descriptive thesis holds that the most fundamental psychological challenge to egalitarian ideals comes from what......Debates over egalitarianism for the most part are not concerned with constraints on achieving an egalitarian society, beyond discussions of the deficiencies of egalitarian theory itself. This paper looks beyond objections to egalitarianism as such and investigates the relevant psychological...

  12. Chemical evolutionary games.

    Science.gov (United States)

    Aristotelous, Andreas C; Durrett, Richard

    2014-05-01

    Inspired by the use of hybrid cellular automata in modeling cancer, we introduce a generalization of evolutionary games in which cells produce and absorb chemicals, and the chemical concentrations dictate the death rates of cells and their fitnesses. Our long term aim is to understand how the details of the interactions in a system with n species and m chemicals translate into the qualitative behavior of the system. Here, we study two simple 2×2 games with two chemicals and revisit the two and three species versions of the one chemical colicin system studied earlier by Durrett and Levin (1997). We find that in the 2×2 examples, the behavior of our new spatial model can be predicted from that of the mean field differential equation using ideas of Durrett and Levin (1994). However, in the three species colicin model, the system with diffusion does not have the coexistence which occurs in the lattices model in which sites interact with only their nearest neighbors. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Evolutionary and developmental modules.

    Science.gov (United States)

    Lacquaniti, Francesco; Ivanenko, Yuri P; d'Avella, Andrea; Zelik, Karl E; Zago, Myrka

    2013-01-01

    The identification of biological modules at the systems level often follows top-down decomposition of a task goal, or bottom-up decomposition of multidimensional data arrays into basic elements or patterns representing shared features. These approaches traditionally have been applied to mature, fully developed systems. Here we review some results from two other perspectives on modularity, namely the developmental and evolutionary perspective. There is growing evidence that modular units of development were highly preserved and recombined during evolution. We first consider a few examples of modules well identifiable from morphology. Next we consider the more difficult issue of identifying functional developmental modules. We dwell especially on modular control of locomotion to argue that the building blocks used to construct different locomotor behaviors are similar across several animal species, presumably related to ancestral neural networks of command. A recurrent theme from comparative studies is that the developmental addition of new premotor modules underlies the postnatal acquisition and refinement of several different motor behaviors in vertebrates.

  14. Industrial Applications of Evolutionary Algorithms

    CERN Document Server

    Sanchez, Ernesto; Tonda, Alberto

    2012-01-01

    This book is intended as a reference both for experienced users of evolutionary algorithms and for researchers that are beginning to approach these fascinating optimization techniques. Experienced users will find interesting details of real-world problems, and advice on solving issues related to fitness computation, modeling and setting appropriate parameters to reach optimal solutions. Beginners will find a thorough introduction to evolutionary computation, and a complete presentation of all evolutionary algorithms exploited to solve different problems. The book could fill the gap between the

  15. Increased albumin permeation in eyes, aorta, and kidney of hypertensive rats fed galactose

    International Nuclear Information System (INIS)

    Tilton, R.G.; LaRose, L.; Chang, K.; Weigel, C.J.; Williamson, J.R.

    1986-01-01

    These experiments were undertaken to determine whether ingestion of galactose increases albumin permeation in the vasculature of hypertensive rats. 50% dextrin (control) or 50% galactose diets were fed to unilaterally nephrectomized, male Sprague-Dawley rats weighing 200 g. Hypertension (systolic pressure >175 mmHg) was induced by weekly IM injections of 25 mg/kg DOCA and 1% saline drinking water; 3 months later 125 I-albumin permeation was assessed in whole eyes, aorta and kidneys. 125 I-albumin permeation was significantly increased in all 3 tissues of hypertensive rats (n = 9) vs controls (n = 9): aorta (3.30 +/- 0.19 (SD) vs 2.87 +/- 0.14), eye (3.15 +/- 0.14 vs 2.59 +/- 0.11), and kidney (6.58 +/- 0.63 vs 3.85 +/- 0.50). Albumin permeation was increased still further in hypertensive rats fed the galactose diet (n = 8): aorta (3.75 +/- 0.38), eye (3.82 +/- 0.17), and kidney (10.74 +/- 3.13). Hypertension +/- galactose feeding had no effect on albumin permeation in lung, skin, or brain. These findings indicate that: (1) hypertension increases albumin permeation in vessels affected by diabetic vascular diseases, and 2) hypertension-induced increases in albumin permeation are increased still further by galactose ingestion, presumably mediated by imbalances in polyol/insitol metabolism (analogous to those induced by diabetes) independent of hyperglycemia and/or insulinopenia

  16. Effect of pressure sensitive adhesive and vehicles on permeation of terbinafine across porcine hoof membrane.

    Science.gov (United States)

    Ahn, Tai Sang; Lee, Jung-Phil; Kim, Juhyun; Oh, Seaung Youl; Chun, Myung-Kwan; Choi, Hoo-Kyun

    2013-11-01

    The purpose of this study was to investigate characteristics of transungual drug delivery and the feasibility of developing a drug-in-adhesive formulation of terbinafine. The permeation of terbinafine from a PSA matrix across porcine hoof membrane was determined using a plate containing poloxamer gel. The permeation rate of terbinafine across hairless mouse skin was evaluated using a flow-through diffusion cell system. The permeation of terbinafine across the hoof membranes was the highest from the silicone adhesive matrix, followed by PIB, and most of the acrylic adhesives, SIS, and SBS. The rank order of permeation rate across mice skin was different from the rank order across porcine hooves. The amount of terbinafine permeated across the porcine hoof membranes poorly correlated with the amount of terbinafine remaining inside the hooves after 20 days, however, the ratio between rate of terbinafine partitioning into the hoof membrane and its rate of diffusion across the membrane was relatively constant within the same type of PSA. For influence of various vehicles in enhancing permeation of terbinafine across the hoof membrane, all vehicles except Labrasol(®) showed tendency to improve permeation rate. However, the enhancement ratio of a given vehicle differed from one adhesive to another with a moderate correlation between them. The infrared spectrum of the hoof treated with NMP, PPG 400 or PEG 200 indicated that the conformation of keratin changed from a non-helical to a helical structure.

  17. SAMPA: A free software tool for skin and membrane permeation data analysis.

    Science.gov (United States)

    Bezrouk, Aleš; Fiala, Zdeněk; Kotingová, Lenka; Krulichová, Iva Selke; Kopečná, Monika; Vávrová, Kateřina

    2017-10-01

    Skin and membrane permeation experiments comprise an important step in the development of a transdermal or topical formulation or toxicological risk assessment. The standard method for analyzing these data relies on the linear part of a permeation profile. However, it is difficult to objectively determine when the profile becomes linear, or the experiment duration may be insufficient to reach a maximum or steady state. Here, we present a software tool for Skin And Membrane Permeation data Analysis, SAMPA, that is easy to use and overcomes several of these difficulties. The SAMPA method and software have been validated on in vitro and in vivo permeation data on human, pig and rat skin and model stratum corneum lipid membranes using compounds that range from highly lipophilic polycyclic aromatic hydrocarbons to highly hydrophilic antiviral drug, with and without two permeation enhancers. The SAMPA performance was compared with the standard method using a linear part of the permeation profile and a complex mathematical model. SAMPA is a user-friendly, open-source software tool for analyzing the data obtained from skin and membrane permeation experiments. It runs on a Microsoft Windows platform and is freely available as a Supporting file to this article. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Effect of permeation enhancers on the penetration mechanism of transfersomal gel of ketoconazole

    Directory of Open Access Journals (Sweden)

    Reshmy Rajan

    2012-01-01

    Full Text Available The aim of the present research work was to investigate the potential of transfersome formulations for transdermal delivery of Ketoconazole (KTZ. KTZ is a broad-spectrum antifungal agent that is active against a wide variety of fungi and yeasts. It is readily but incompletely absorbed after oral dosing and is highly variable. The transfersomes were formulated by lipid film hydration technique using Rotary vacuum Evaporator. The prepared transfersomes were converted into suitable gel formulation and is evaluated for their gel characteristics like pH, viscosity, spreadability, extrudability, homogeneity, drug content, etc. Suitable essential oils acting as natural permeation enhancers were added to the transfersomal formulation of KTZ for their release studies. Studies proved that addition of suitable permeation enhancers to the transfersomal formulation improved the release and permeation of KTZ, which showed that the permeation enhancers modify the barrier to penetration present in skin without itself undergoing any change. From the various essential oils which are used as permeation enhancers, the formulation containing Eucalyptus oil showed better in vitro release and permeation as compared with other formulations containing different permeation enhancers.

  19. Constraint-based scheduling applying constraint programming to scheduling problems

    CERN Document Server

    Baptiste, Philippe; Nuijten, Wim

    2001-01-01

    Constraint Programming is a problem-solving paradigm that establishes a clear distinction between two pivotal aspects of a problem: (1) a precise definition of the constraints that define the problem to be solved and (2) the algorithms and heuristics enabling the selection of decisions to solve the problem. It is because of these capabilities that Constraint Programming is increasingly being employed as a problem-solving tool to solve scheduling problems. Hence the development of Constraint-Based Scheduling as a field of study. The aim of this book is to provide an overview of the most widely used Constraint-Based Scheduling techniques. Following the principles of Constraint Programming, the book consists of three distinct parts: The first chapter introduces the basic principles of Constraint Programming and provides a model of the constraints that are the most often encountered in scheduling problems. Chapters 2, 3, 4, and 5 are focused on the propagation of resource constraints, which usually are responsibl...

  20. Modeling the Effects of Interfacial Characteristics on Gas Permeation Behavior of Nanotube-Mixed Matrix Membranes.

    Science.gov (United States)

    Chehrazi, Ehsan; Sharif, Alireza; Omidkhah, Mohammadreza; Karimi, Mohammad

    2017-10-25

    Theoretical approaches that accurately predict the gas permeation behavior of nanotube-containing mixed matrix membranes (nanotube-MMMs) are scarce. This is mainly due to ignoring the effects of nanotube/matrix interfacial characteristics in the existing theories. In this paper, based on the analogy of thermal conduction in polymer composites containing nanotubes, we develop a model to describe gas permeation through nanotube-MMMs. Two new parameters, "interfacial thickness" (a int ) and "interfacial permeation resistance" (R int ), are introduced to account for the role of nanotube/matrix interfacial interactions in the proposed model. The obtained values of a int , independent of the nature of the permeate gas, increased by increasing both the nanotubes aspect ratio and polymer-nanotube interfacial strength. An excellent correlation between the values of a int and polymer-nanotube interaction parameters, χ, helped to accurately reproduce the existing experimental data from the literature without the need to resort to any adjustable parameter. The data includes 10 sets of CO 2 /CH 4 permeation, 12 sets of CO 2 /N 2 permeation, 3 sets of CO 2 /O 2 permeation, and 2 sets of CO 2 /H 2 permeation through different nanotube-MMMs. Moreover, the average absolute relative errors between the experimental data and the predicted values of the proposed model are very small (less than 5%) in comparison with those of the existing models in the literature. To the best of our knowledge, this is the first study where such a systematic comparison between model predictions and such extensive experimental data is presented. Finally, the new way of assessing gas permeation data presented in the current work would be a simple alternative to complex approaches that are usually utilized to estimate interfacial thickness in polymer composites.

  1. Changes in chemical permeation of disposable latex, nitrile, and vinyl gloves exposed to simulated movement.

    Science.gov (United States)

    Phalen, Robert N; Le, Thi; Wong, Weng Kee

    2014-01-01

    Glove movement can affect chemical permeation of organic compounds through polymer glove products. However, conflicting reports make it difficult to compare the effects of movement on chemical permeation through commonly available glove types. The aim of this study was to evaluate the effect of movement on chemical permeation of an organic solvent through disposable latex, nitrile, and vinyl gloves. Simulated whole-glove permeation testing was conducted using ethyl alcohol and a previously designed permeation test system. With exposure to movement, a significant decrease (p ≤ 0.001) in breakthrough time (BT) was observed for the latex (-23%) and nitrile gloves (-31%). With exposure to movement, only the nitrile glove exhibited a significant increase (p ≤ 0.001) in steady-state permeation rate (+47%) and cumulative permeation at 30 min (+111%). Even though the nitrile glove provided optimum chemical resistance against ethyl alcohol, it was most affected by movement. With exposure to movement, the latex glove was an equivalent option for overall worker protection, because it was less affected by movement and the permeation rate was lower than that of the nitrile glove. In contrast, the vinyl glove was the least affected by movement, but did not provide adequate chemical resistance to ethyl alcohol in comparison with the nitrile and latex gloves. Glove selection should take movement and polymer type into account. Some glove polymer types are less affected by movement, most notably the latex glove in this test. With nitrile gloves, at least a factor of three should be used when attempting to assign a protection factor when repetitive hand motions are anticipated. Ultimately, the latex gloves outperformed nitrile and vinyl in these tests, which evaluated the effect of movement on chemical permeation. Future research should aim to resolve some of the observed discrepancies in test results with latex and vinyl gloves.

  2. Human skin in vitro permeation of bentazon and isoproturon formulations with or without protective clothing suit.

    Science.gov (United States)

    Berthet, Aurélie; Hopf, Nancy B; Miles, Alexandra; Spring, Philipp; Charrière, Nicole; Garrigou, Alain; Baldi, Isabelle; Vernez, David

    2014-01-01

    Skin exposures to chemicals may lead, through percutaneous permeation, to a significant increase in systemic circulation. Skin is the primary route of entry during some occupational activities, especially in agriculture. To reduce skin exposures, the use of personal protective equipment (PPE) is recommended. PPE efficiency is characterized as the time until products permeate through material (lag time, Tlag). Both skin and PPE permeations are assessed using similar in vitro methods; the diffusion cell system. Flow-through diffusion cells were used in this study to assess the permeation of two herbicides, bentazon and isoproturon, as well as four related commercial formulations (Basagran(®), Basamais(®), Arelon(®) and Matara(®)). Permeation was measured through fresh excised human skin, protective clothing suits (suits) (Microchem(®) 3000, AgriSafe Pro(®), Proshield(®) and Microgard(®) 2000 Plus Green), and a combination of skin and suits. Both herbicides, tested by itself or as an active ingredient in formulations, permeated readily through human skin and tested suits (Tlag < 2 h). High permeation coefficients were obtained regardless of formulations or tested membranes, except for Microchem(®) 3000. Short Tlag, were observed even when skin was covered with suits, except for Microchem(®) 3000. Kp values tended to decrease when suits covered the skin (except when Arelon(®) was applied to skin covered with AgriSafe Pro and Microgard(®) 2000), suggesting that Tlag alone is insufficient in characterizing suits. To better estimate human skin permeations, in vitro experiments should not only use human skin but also consider the intended use of the suit, i.e., the active ingredient concentrations and type of formulations, which significantly affect skin permeation.

  3. SC lipid model membranes designed for studying impact of ceramide species on drug diffusion and permeation--part II: diffusion and permeation of model drugs.

    Science.gov (United States)

    Ochalek, M; Podhaisky, H; Ruettinger, H-H; Wohlrab, J; Neubert, R H H

    2012-10-01

    The barrier function of two quaternary stratum corneum (SC) lipid model membranes, which were previously characterized with regard to the lipid organization, was investigated based on diffusion studies of model drugs with varying lipophilicities. Diffusion experiments of a hydrophilic drug, urea, and more lipophilic drugs than urea (i.e. caffeine, diclofenac sodium) were conducted using Franz-type diffusion cells. The amount of permeated drug was analyzed using either HPLC or CE technique. The subjects of interest in the present study were the investigation of the influence of physicochemical properties of model drugs on their diffusion and permeation through SC lipid model membranes, as well as the study of the impact of the constituents of these artificial systems (particularly ceramide species) on their barrier properties. The diffusion through both SC lipid model membranes and the human SC of the most hydrophilic model drug, urea, was faster than the permeation of the more lipophilic drugs. The slowest rate of permeation through SC lipid systems occurred in the case of caffeine. The composition of SC lipid model membranes has a significant impact on their barrier function. Model drugs diffused and permeated faster through Membrane II (presence of Cer [EOS]). In terms of the barrier properties, Membrane II is much more similar to the human SC than Membrane I. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Constraints on Dbar uplifts

    International Nuclear Information System (INIS)

    Alwis, S.P. de

    2016-01-01

    We discuss constraints on KKLT/KKLMMT and LVS scenarios that use anti-branes to get an uplift to a deSitter vacuum, coming from requiring the validity of an effective field theory description of the physics. We find these are not always satisfied or are hard to satisfy.

  5. Ecosystems emerging. 5: Constraints

    Czech Academy of Sciences Publication Activity Database

    Patten, B. C.; Straškraba, Milan; Jorgensen, S. E.

    2011-01-01

    Roč. 222, č. 16 (2011), s. 2945-2972 ISSN 0304-3800 Institutional research plan: CEZ:AV0Z50070508 Keywords : constraint * epistemic * ontic Subject RIV: EH - Ecology, Behaviour Impact factor: 2.326, year: 2011 http://www.sciencedirect.com/science/article/pii/S0304380011002274

  6. Constraints and Ambiguity

    DEFF Research Database (Denmark)

    Dove, Graham; Biskjær, Michael Mose; Lundqvist, Caroline Emilie

    2017-01-01

    groups of students building three models each. We studied groups building with traditional plastic bricks and also using a digital environment. The building tasks students undertake, and our subsequent analysis, are informed by the role constraints and ambiguity play in creative processes. Based...

  7. A Semiotic Analysis of the Interface between Evolutionary and Developmental Processes

    Directory of Open Access Journals (Sweden)

    Eugenio Andrade

    2008-07-01

    Full Text Available This work proposes the notion of organisms as Evolving Developing Agents (EDA in order to ground an internalist model in which evolution and development are conceived as aspects of a general transformative tendency driven by organism's need to cope with environmental uncertainty. It is shown how the integration Evo/Devo contributes to an expanded evolutionary synthesis that accounts for divergent evolution in terms of development, without disregarding the role of genes and natural selection. However this integration has to be seen as a specific case that contributes to the contextualization of C.S.Peirce's evolutionary ontology founded on three universal categories and six space/time/function relations, as described by Taborsky. The role played by the EDA is characterized by the Secondness as firstness relation for it merges the internal/ external, and individual/population and present/past/ progressive cuts that permeate the discourse of biology.

  8. Permeation of a H2 + HD + D2 gas mixture through a polymer membrane

    International Nuclear Information System (INIS)

    Mercea, P.; Cuna, S.; Kreibik, S.; Ursu, I.

    1990-01-01

    The selective permeation of a H 2 + HD + D 2 gas mixture through a polyethylene terephthalate membrane was studied at T 20 0 C. It was found that the permeation of the HD through the membrane leads to a smaller overall hydrogen-deuterium separation factor than that determined in the permeation experiments with pure H 2 and D 2 . On the other hand, a process of isotopic exchange between deuterium atoms from the penetrant gas stream and hydrogen atoms from the polymer membrane is assumed and discussed in order to explain temporal variations of the H 2 , HD and D 2 concentrations of the permanent gas stream. (author)

  9. Practical experience of backwashing with SWRO permeate for UF fouling control

    KAUST Repository

    Li, Sheng; Heijman, Sebastiaan G J; Verberk, J. Q J C; Amy, Gary L.; Van Dijk, Johannis C.

    2013-01-01

    Effectiveness of seawater reverse osmosis (SWRO) permeate backwash on fouling control of seawater ultrafiltration was investigated at a pilot scale. A standard membrane module was used in this pilot to represent full-scale desalination plants. Results of the pilot show a good reproducibility. When the UF permeate was used for backwash, the frequency of chemically enhanced backwash (CEB) was around once per day. However, results of the pilot show that SWRO permeate backwashing could significantly reduce the CEB frequency. © 2013 Desalination Publications.

  10. Gas-driven permeation of deuterium through tungsten and tungsten alloys

    Energy Technology Data Exchange (ETDEWEB)

    Buchenauer, Dean A., E-mail: dabuche@sandia.gov [Sandia National Laboratories, Energy Innovation Department, Livermore, CA 94550 (United States); Karnesky, Richard A. [Sandia National Laboratories, Energy Innovation Department, Livermore, CA 94550 (United States); Fang, Zhigang Zak; Ren, Chai [University of Utah, Department of Metallurgical Engineering, Salt Lake City, UT 84112 (United States); Oya, Yasuhisa [Shizuoka University, Graduate School of Science, Shizuoka (Japan); Otsuka, Teppei [Kyushu University, Department of Advanced Energy Engineering Science, Fukuoka (Japan); Yamauchi, Yuji [Hokkaido University, Third Division of Quantum Science and Engineering, Faculty of Engineering, Sapporo (Japan); Whaley, Josh A. [Sandia National Laboratories, Energy Innovation Department, Livermore, CA 94550 (United States)

    2016-11-01

    Highlights: • We have designed and performed initial studies on a high temperature gas-driven permeation cell capable of operating at temperatures up to 1150 °C and at pressures between 0.1–1 atm. • Permeation measurements on ITER grade tungsten compare well with past studies by Frauenfelder and Zahkarov in the temperature range from 500 to 1000 °C. • First permeation measurements on Ti dispersoid-strengthened ultra-fine grained tungsten show higher permeation at 500 °C, but very similar permeation with ITER tungsten at 1000 °C. Diffusion along grain boundaries may be playing a role for this type of material. - Abstract: To address the transport and trapping of hydrogen isotopes, several permeation experiments are being pursued at both Sandia National Laboratories (deuterium gas-driven permeation) and Idaho National Laboratories (tritium gas- and plasma-driven tritium permeation). These experiments are in part a collaboration between the US and Japan to study the performance of tungsten at divertor relevant temperatures (PHENIX). Here we report on the development of a high temperature (≤1150 °C) gas-driven permeation cell and initial measurements of deuterium permeation in several types of tungsten: high purity tungsten foil, ITER-grade tungsten (grains oriented through the membrane), and dispersoid-strengthened ultra-fine grain (UFG) tungsten being developed in the US. Experiments were performed at 500–1000 °C and 0.1–1.0 atm D{sub 2} pressure. Permeation through ITER-grade tungsten was similar to earlier W experiments by Frauenfelder (1968–69) and Zaharakov (1973). Data from the UFG alloy indicates marginally higher permeability (< 10×) at lower temperatures, but the permeability converges to that of the ITER tungsten at 1000 °C. The permeation cell uses only ceramic and graphite materials in the hot zone to reduce the possibility for oxidation of the sample membrane. Sealing pressure is applied externally, thereby allowing for elevation

  11. Tritium permeation in stainless-steel structures exposed to plasma ions

    International Nuclear Information System (INIS)

    Anderl, R.A.; Holland, D.F.; Struttmann, D.A.; Longhurst, G.R.; Merrill, B.J.

    1985-01-01

    This paper presents a comparison of the hydrogen permeation properties of the austenitic primary candidate alloy, PCA, and of the advanced ferritic alloy, HT-9. The comparison is based on experimental measurements of the permeation and reemission of deuterium from specimens undergoing implantation with 3-keV, D 3 + ions produced by an accelerator. Characterization of the specimen surface facing the ion beam is provided by secondary ion mass spectrometer (SIMS) analysis of the species sputtered from the surface during the implantation. Recombination and diffusivity data for PCA and HT-9 were derived from an analysis in which model calculations were applied to the reemission and permeation measurements

  12. Investigation on the suitability of plasma sprayed Fe-Cr-Al coatings as tritium permeation barrier

    International Nuclear Information System (INIS)

    Fazio, C.; Serra, E.; Benamati, G.

    1999-01-01

    Results on the fabrication of a tritium permeation barrier by spraying Fe-Cr-Al powders are described. The sprayed coatings were deposited at temperatures below the A c1 temperature of the ferritic-martensitic steel substrate and no post-deposition heat treatment was applied. The aim of the investigation was the determination of the efficiency of the coatings to act as tritium permeation barrier. Metallurgical investigations as well as hydrogen isotope permeation measurements were carried out onto the produced coatings. The depositions were performed on ferritic-martensitic steels by means of three types of spray techniques: high velocity oxy fuel, air plasma spray and vacuum plasma spray. (orig.)

  13. NMR experiments on ion permeation in irradiated model membranes

    International Nuclear Information System (INIS)

    Sprinz, H.; Winkler, E.; Schaefer, H.

    1981-01-01

    In aqueous solutions of egg-lecithin vesicles treated with ultrasonics the 1 H NMR parameters line width, area, and chemical shift of the signal of the (CH 3 ) 3 N + group were determined as a function of the gamma dose (0 ... 12 kGy). Using europium and the line shape analysis, it has been possible to calculate these parameters for the inside as well as for the outside lipid layer. Increasing 60 Co radiation dose leads to linear increases of the line widths, which are significantly more rapid for the outer than for the inner layer. From that it can be concluded that the outside lipid layer has been more damaged by irradiation. The asymmetry may be the consequence of a radiation effect induced by the radicals of water radiolysis. From the temporal changes of the NMR parameters information can be obtained about the radiation effect on transport processes in the vesicles. Beginning at a threshold (approx. 5 kGy) the permeation of Eu +++ ions to the (CH 3 ) 3 N + head groups, previously not accessible, increases significantly. (author)

  14. Ion Permeation and Mechanotransduction Mechanisms of Mechanosensitive Piezo Channels.

    Science.gov (United States)

    Zhao, Qiancheng; Wu, Kun; Geng, Jie; Chi, Shaopeng; Wang, Yanfeng; Zhi, Peng; Zhang, Mingmin; Xiao, Bailong

    2016-03-16

    Piezo proteins have been proposed as the long-sought-after mechanosensitive cation channels in mammals that play critical roles in various mechanotransduction processes. However, the molecular bases that underlie their ion permeation and mechanotransduction have remained functionally undefined. Here we report our finding of the miniature pore-forming module of Piezo1 that resembles the pore architecture of other trimeric channels and encodes the essential pore properties. We further identified specific residues within the pore module that determine unitary conductance, pore blockage and ion selectivity for divalent and monovalent cations and anions. The non-pore-containing region of Piezo1 confers mechanosensitivity to mechano-insensitive trimeric acid-sensing ion channels, demonstrating that Piezo1 channels possess intrinsic mechanotransduction modules separate from their pore modules. In conclusion, this is the first report on the bona fide pore module and mechanotransduction components of Piezo channels, which define their ion-conducting properties and gating by mechanical stimuli, respectively. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. Molluscan Evolutionary Genomics

    Energy Technology Data Exchange (ETDEWEB)

    Simison, W. Brian; Boore, Jeffrey L.

    2005-12-01

    In the last 20 years there have been dramatic advances in techniques of high-throughput DNA sequencing, most recently accelerated by the Human Genome Project, a program that has determined the three billion base pair code on which we are based. Now this tremendous capability is being directed at other genome targets that are being sampled across the broad range of life. This opens up opportunities as never before for evolutionary and organismal biologists to address questions of both processes and patterns of organismal change. We stand at the dawn of a new 'modern synthesis' period, paralleling that of the early 20th century when the fledgling field of genetics first identified the underlying basis for Darwin's theory. We must now unite the efforts of systematists, paleontologists, mathematicians, computer programmers, molecular biologists, developmental biologists, and others in the pursuit of discovering what genomics can teach us about the diversity of life. Genome-level sampling for mollusks to date has mostly been limited to mitochondrial genomes and it is likely that these will continue to provide the best targets for broad phylogenetic sampling in the near future. However, we are just beginning to see an inroad into complete nuclear genome sequencing, with several mollusks and other eutrochozoans having been selected for work about to begin. Here, we provide an overview of the state of molluscan mitochondrial genomics, highlight a few of the discoveries from this research, outline the promise of broadening this dataset, describe upcoming projects to sequence whole mollusk nuclear genomes, and challenge the community to prepare for making the best use of these data.

  16. Evolutionary disarmament in interspecific competition.

    Science.gov (United States)

    Kisdi, E; Geritz, S A

    2001-12-22

    Competitive asymmetry, which is the advantage of having a larger body or stronger weaponry than a contestant, drives spectacular evolutionary arms races in intraspecific competition. Similar asymmetries are well documented in interspecific competition, yet they seldom lead to exaggerated traits. Here we demonstrate that two species with substantially different size may undergo parallel coevolution towards a smaller size under the same ecological conditions where a single species would exhibit an evolutionary arms race. We show that disarmament occurs for a wide range of parameters in an ecologically explicit model of competition for a single shared resource; disarmament also occurs in a simple Lotka-Volterra competition model. A key property of both models is the interplay between evolutionary dynamics and population density. The mechanism does not rely on very specific features of the model. Thus, evolutionary disarmament may be widespread and may help to explain the lack of interspecific arms races.

  17. Evolutionary computation for reinforcement learning

    NARCIS (Netherlands)

    Whiteson, S.; Wiering, M.; van Otterlo, M.

    2012-01-01

    Algorithms for evolutionary computation, which simulate the process of natural selection to solve optimization problems, are an effective tool for discovering high-performing reinforcement-learning policies. Because they can automatically find good representations, handle continuous action spaces,

  18. Evolutionary genetics: the Drosophila model

    Indian Academy of Sciences (India)

    Unknown

    Evolutionary genetics straddles the two fundamental processes of life, ... of the genus Drosophila have been used extensively as model systems in experimental ... issue will prove interesting, informative and thought-provoking for both estab-.

  19. Integrating genomics into evolutionary medicine.

    Science.gov (United States)

    Rodríguez, Juan Antonio; Marigorta, Urko M; Navarro, Arcadi

    2014-12-01

    The application of the principles of evolutionary biology into medicine was suggested long ago and is already providing insight into the ultimate causes of disease. However, a full systematic integration of medical genomics and evolutionary medicine is still missing. Here, we briefly review some cases where the combination of the two fields has proven profitable and highlight two of the main issues hindering the development of evolutionary genomic medicine as a mature field, namely the dissociation between fitness and health and the still considerable difficulties in predicting phenotypes from genotypes. We use publicly available data to illustrate both problems and conclude that new approaches are needed for evolutionary genomic medicine to overcome these obstacles. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Evolutionary robotics – A review

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    a need for a technique by which the robot is able to acquire new behaviours automatically .... Evolutionary robotics is a comparatively new field of robotics research, which seems to ..... Technical Report: PCIA-94-04, Institute of Psychology,.

  1. Evolutionary rate patterns of the Gibberellin pathway genes

    Directory of Open Access Journals (Sweden)

    Zhang Fu-min

    2009-08-01

    Full Text Available Abstract Background Analysis of molecular evolutionary patterns of different genes within metabolic pathways allows us to determine whether these genes are subject to equivalent evolutionary forces and how natural selection shapes the evolution of proteins in an interacting system. Although previous studies found that upstream genes in the pathway evolved more slowly than downstream genes, the correlation between evolutionary rate and position of the genes in metabolic pathways as well as its implications in molecular evolution are still less understood. Results We sequenced and characterized 7 core structural genes of the gibberellin biosynthetic pathway from 8 representative species of the rice tribe (Oryzeae to address alternative hypotheses regarding evolutionary rates and patterns of metabolic pathway genes. We have detected significant rate heterogeneity among 7 GA pathway genes for both synonymous and nonsynonymous sites. Such rate variation is mostly likely attributed to differences of selection intensity rather than differential mutation pressures on the genes. Unlike previous argument that downstream genes in metabolic pathways would evolve more slowly than upstream genes, the downstream genes in the GA pathway did not exhibited the elevated substitution rate and instead, the genes that encode either the enzyme at the branch point (GA20ox or enzymes catalyzing multiple steps (KO, KAO and GA3ox in the pathway had the lowest evolutionary rates due to strong purifying selection. Our branch and codon models failed to detect signature of positive selection for any lineage and codon of the GA pathway genes. Conclusion This study suggests that significant heterogeneity of evolutionary rate of the GA pathway genes is mainly ascribed to differential constraint relaxation rather than the positive selection and supports the pathway flux theory that predicts that natural selection primarily targets enzymes that have the greatest control on fluxes.

  2. Evolutionary Game Theory: A Renaissance

    Directory of Open Access Journals (Sweden)

    Jonathan Newton

    2018-05-01

    Full Text Available Economic agents are not always rational or farsighted and can make decisions according to simple behavioral rules that vary according to situation and can be studied using the tools of evolutionary game theory. Furthermore, such behavioral rules are themselves subject to evolutionary forces. Paying particular attention to the work of young researchers, this essay surveys the progress made over the last decade towards understanding these phenomena, and discusses open research topics of importance to economics and the broader social sciences.

  3. Freud: the first evolutionary psychologist?

    Science.gov (United States)

    LeCroy, D

    2000-04-01

    An evolutionary perspective on attachment theory and psychoanalytic theory brings these two fields together in interesting ways. Application of the evolutionary principle of parent-offspring conflict to attachment theory suggests that attachment styles represent context-sensitive, evolved (adaptive) behaviors. In addition, an emphasis on offspring counter-strategies to adult reproductive strategies leads to consideration of attachment styles as overt manifestations of psychodynamic mediating processes, including the defense mechanisms of repression and reaction formation.

  4. Estimating true evolutionary distances under the DCJ model.

    Science.gov (United States)

    Lin, Yu; Moret, Bernard M E

    2008-07-01

    Modern techniques can yield the ordering and strandedness of genes on each chromosome of a genome; such data already exists for hundreds of organisms. The evolutionary mechanisms through which the set of the genes of an organism is altered and reordered are of great interest to systematists, evolutionary biologists, comparative genomicists and biomedical researchers. Perhaps the most basic concept in this area is that of evolutionary distance between two genomes: under a given model of genomic evolution, how many events most likely took place to account for the difference between the two genomes? We present a method to estimate the true evolutionary distance between two genomes under the 'double-cut-and-join' (DCJ) model of genome rearrangement, a model under which a single multichromosomal operation accounts for all genomic rearrangement events: inversion, transposition, translocation, block interchange and chromosomal fusion and fission. Our method relies on a simple structural characterization of a genome pair and is both analytically and computationally tractable. We provide analytical results to describe the asymptotic behavior of genomes under the DCJ model, as well as experimental results on a wide variety of genome structures to exemplify the very high accuracy (and low variance) of our estimator. Our results provide a tool for accurate phylogenetic reconstruction from multichromosomal gene rearrangement data as well as a theoretical basis for refinements of the DCJ model to account for biological constraints. All of our software is available in source form under GPL at http://lcbb.epfl.ch.

  5. Permeation of hydrogen at low pressures through stainless steel and implications for tritium control in fusion reactor systems

    International Nuclear Information System (INIS)

    Axtmann, R.C.; Johnson, E.F.; Kuehler, C.W.

    1976-01-01

    New experimental data on the permeation of hydrogen through stainless steel indicate that at driving pressures below 10 -2 torr, the permeation rate is linearly dependent on the driving pressure. A possible consequence is that the permeation rates of hydrogenic species in fusion reactor systems might be much lower than those reported in contemporary conceptual design studies which assume that the rates are dependent on the square root of the driving pressure. The important implications of these low permeation rates are: (1) tritium losses to the environment may be more dependent on ordinary leaks from equipment than on permeation to the steam cycle; (2) recovery of tritium from breeding blankets via permeation windows may be impracticable; and (3) recovery of tritium from breeding blankets not dependent on permeation windows may be simplified by the possibility of operating at much higher average tritium concentrations in the blanket and cooling systems

  6. Experimental evaluation of tritium permeation through stainless steel tubes of heat exchanger from primary to secondary water in ITER

    International Nuclear Information System (INIS)

    Nakamura, Hirofumi; Nishi, Masataka

    2004-01-01

    Tritium permeation through heat exchanger from primary cooling water to secondary cooling water has been investigated experimentally with SS316L heat exchanger under simulated ITER (international thermonuclear experimental reactor) operation condition in order to establish the tritium permeation evaluation method through the heat exchanger. As the result, the permeation rate of aqueous tritium was found to be about three orders smaller than that of the gaseous tritium. Tritium permeation through the heat exchanger in ITER was then evaluated, and it was revealed that total tritium permeation amount based on obtained aqueous permeability was about one order less than that with the former method with the gaseous permeability and putting the permeation reduction factor as 1000. Evaluated tritium permeation amount into secondary water during 20 years was quite small, which could be considered as negligible from the safety viewpoint

  7. Research on Crack-Filling Heat Treatment and Hydrogen Permeation Test of Self-healing Tritium Permeation Barriers

    Science.gov (United States)

    Liu, Dawei; Wang, Yan; Zhang, Ying; Ouyang, Taoyuan; Zhou, Tong; Fang, Xuanwei; Suo, Jinping

    2018-03-01

    A TiC + mixture (TiC/Al2O3 (1:1 wt.%)) +Al2O3 self-healing triple layer coating (TLC) was designed and manufactured by our group, and the crack-filling heat treatment process had been roughly explored in the past. In this work, the accelerating test with a thick TiC + mixture (TiC/Al2O3 (1:1 wt.%)) double-layer coating (DLC) was carried out. The DLC coating warped when the heat treatment temperature was lower than 550 °C, which was rare in similar researches, and it crushed into fan-shaped pieces when the treatment temperature was higher than 650 °C. The two different spalling failures were explained by weight gain, porosity and stress analyses. The heating rate had a significant effect. The bonding strength and hydrogen permeation of the TLC samples were also tested. Remaining at 650 °C for 40 h was proved to be an optimal crack-filling heat treatment process, considering the hydrogen resistance.

  8. Alteration of skin hydration and its barrier function by vehicle and permeation enhancers: a study using TGA, FTIR, TEWL and drug permeation as markers.

    Science.gov (United States)

    Shah, D K; Khandavilli, S; Panchagnula, R

    2008-09-01

    Vehicles and permeation enhancers (PEs) used in transdermal drug delivery (TDD) of a drug can affect skin hydration, integrity and permeation of the solute administered. This investigation was designed to study the effect of the most commonly used vehicles and PEs on rat skin hydration, barrier function and permeation of an amphiphilic drug, imipramine hydrochloride (IMH). An array of well-established techniques were used to confirm the findings of the study. Thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy were used to determine changes in skin hydration. Alteration of the stratum corneum (SC) structure was investigated using FTIR studies. To monitor the barrier function alteration, transepidermal water loss (TEWL) measurement and permeation studies were performed. Our findings indicate that with hydration, there was an increase in the bound water content of the skin, and pseudoequilibrium of hydration (a drastic decrease in hydration rate) was achieved at around 12 h. Hydration increased the ratio between amide-I and amide-II peaks in FTIR and reduced the C-H stretching peak area. Both propylene glycol (PG) and ethanol (EtOH) dehydrated skin, with the latter showing a predominant effect. Furthermore, it was confirmed that PG and EtOH decreased the bound water content due to alteration in the protein domains and extraction of SC lipids, respectively. The effect of hydration on the SC was found to be similar to that reported for temperature. Permeation studies revealed that the dehydration caused by vehicles decreased IMH flux, whereas the flux was enhanced by PEs. The role of partition was predominant for the permeation of IMH through dehydrated skin. A synergistic effect was observed for PG and menthol in the enhancement of IMH. Further findings provided strong evidence that PG affects protein domains and EtOH extracts lipids from the bilayer. Both PG and EtOH, with or without PEs, increased TEWL. Initial TEWL was well

  9. Tritium permeation through helium-heated steam generators of ceramic breeder blankets for DEMO

    International Nuclear Information System (INIS)

    Fuetterer, M.A.; Raepsaet, X.; Proust, E.

    1994-01-01

    The specifications of permeation barriers, tritium recovery process maintaining a very low tritium activity in the coolant, and control of the coolant chemistry, required the evaluation of the tritium losses through the steam generators and include the definition of its operating conditions by thermodynamic cycle calculations and its thermal-hydraulic design. For both tasks specific computer tools were developed. The obtained geometry, surface area, and temperature profiles along the heat exchanger tubes were then used to estimate the daily tritium permeation into the steam cycle. Steam oxidized Incoloy 800 austenitic stainless steel was identified as the best suited existing material; in nominal steady-state operation, the tritium escape into the steam cycle could be restricted to less than 10 Ci/d. Tritium permeation during temperature and pressure transients in the steam generator (destruction and possible self-healing of the permeation barrier) is identified to bear a large tritium release potential. Solutions are proposed. (from authors). 4 figs., 1 tab

  10. Tritium permeation through helium-heated steam generators of ceramic breeder blankets for DEMO

    Energy Technology Data Exchange (ETDEWEB)

    Fuetterer, M A; Raepsaet, X; Proust, E

    1994-12-31

    The specifications of permeation barriers, tritium recovery process maintaining a very low tritium activity in the coolant, and control of the coolant chemistry, required the evaluation of the tritium losses through the steam generators and include the definition of its operating conditions by thermodynamic cycle calculations and its thermal-hydraulic design. For both tasks specific computer tools were developed. The obtained geometry, surface area, and temperature profiles along the heat exchanger tubes were then used to estimate the daily tritium permeation into the steam cycle. Steam oxidized Incoloy 800 austenitic stainless steel was identified as the best suited existing material; in nominal steady-state operation, the tritium escape into the steam cycle could be restricted to less than 10 Ci/d. Tritium permeation during temperature and pressure transients in the steam generator (destruction and possible self-healing of the permeation barrier) is identified to bear a large tritium release potential. Solutions are proposed. (from authors). 4 figs., 1 tab.

  11. Toward enhanced hydrogen generation from water using oxygen permeating LCF membranes

    KAUST Repository

    Wu, Xiao-Yu; Chang, Le; Uddi, Mruthunjaya; Kirchen, Patrick; Ghoniem, Ahmed F.

    2015-01-01

    and flow rates on the feed and sweep sides on the water thermolysis rate and oxygen flux. A single step reaction mechanism is proposed for surface reactions, and three-resistance permeation models are derived. Results show that water thermolysis

  12. Experimental Validation of Hybrid Distillation-Vapor Permeation Process for Energy Efficient Ethanol-Water Separation

    Science.gov (United States)

    The energy demand of distillation-based systems for ethanol recovery and dehydration can be significant, particularly for dilute solutions. An alternative separation process integrating vapor stripping with a vapor compression step and a vapor permeation membrane separation step,...

  13. Formation of permeation barriers on ceramic SiC/SiC composites

    International Nuclear Information System (INIS)

    Racault, C.; Fenici, P.

    1996-01-01

    The effectiveness as permeation barriers of the following CVD and PVD (sputtering) coatings has been investigated: TiC+Al 2 O 3 (CVD), SiC(CVD), SiO 2 (CVD), TiN(CVD), TiN(CVD)+TiN(PVD) and SiC(CVD)+Al 2 O 3 (PVD). The substrate material was a SiC/SiC composite, proposed as low activation structural material for fusion applications. Permeation measurements were performed in the temperature range 300-750 K using deuterium at pressures in the range 0.5-150 kPa. A linear dependence of permeation rate on pressure was measured. The efficiency of the coatings as deuterium permeation barriers is discussed in terms of coating microstructure. The best result was obtained with a bilayer of TiN(CVD) (15 μm) +TiN(PVD) (8 μm). (orig.)

  14. Tritium permeation barriers in contact with liquid lithium-lead eutectic (Pb-17Li)

    International Nuclear Information System (INIS)

    Forcey, K.S.; Perujo, A.

    1995-01-01

    The permeation of deuterium through coated stainless steel tubes containing liquid lithium-lead eutectic (Pb-17Li) has been studied and compared to measurements through tubes without the lithium compound. The measurements form part of an investigation into the effect of a potential tritium breeder material on permeation barriers for fusion reactors. The coatings studied were CVD TiC and Al 2 O 3 and a pack aluminised layer. Without the lithium-lead, the CVD coatings reduced the permeation rate up to 1 order of magnitude, and the aluminised layer up to 2 orders of magnitude. A CVD layer was unaffected by Pb-17Li whilst in the case of the aluminised tube, the lithium-lead completely removed the permeation barrier, presumably by attacking the surface oxide. Furthermore, the aluminised sample presented a large number of cracks and poor adheren ce to the substrate. ((orig.))

  15. Water vapor permeation and dehumidification performance of poly(vinyl alcohol)/lithium chloride composite membranes

    KAUST Repository

    Bui, Duc Thuan; Nida, Aqdas; Ng, Kim  Choon; Chua, Kian  Jon

    2015-01-01

    were observed for membranes with increased lithium chloride content up to 50%. The permeation and sorption properties of the membranes were investigated under different temperatures. The results provided a deeper insight into the membrane water vapor

  16. Water vapor permeation and dehumidification performance of poly(vinyl alcohol)/lithium chloride composite membranes

    KAUST Repository

    Bui, Duc Thuan

    2015-10-09

    Thin and robust composite membranes comprising stainless steel scaffold, fine and porous TiO2 and polyvinyl alcohol/lithium chloride were fabricated and studied for air dehumidification application. Higher hydrophilicity, sorption and permeation were observed for membranes with increased lithium chloride content up to 50%. The permeation and sorption properties of the membranes were investigated under different temperatures. The results provided a deeper insight into the membrane water vapor permeation process. It was specifically noted that lithium chloride significantly reduces water diffusion energy barrier, resulting in the change of permeation energy from positive to negative values. Higher water vapor permeance was observed for the membrane with higher LiCl content at lower temperature. The isothermal air dehumidification tests show that the membrane is suitable for dehumidifying air in high humid condition. Additionally, results also indicate a trade-off between the humidity ratio drop with the water vapor removal rate when varying air flowrate.

  17. Determination of trapping parameters and the chemical diffusion coefficient from hydrogen permeation experiments

    Czech Academy of Sciences Publication Activity Database

    Svoboda, Jiří; Mori, G.; Prethaler, A.; Fischer, F. D.

    2014-01-01

    Roč. 82, MAY (2014), s. 93-100 ISSN 0010-938X Institutional support: RVO:68081723 Keywords : Steel * Electrochemical calculation * Modeling studies * Hydrogen permeation * Kinetic parameters Subject RIV: BJ - Thermodynamics Impact factor: 4.422, year: 2014

  18. Ion-driven permeation of deuterium through tungsten under simultaneous helium and deuterium irradiation

    International Nuclear Information System (INIS)

    Lee, H.T.; Tanaka, H.; Ohtsuka, Y.; Ueda, Y.

    2011-01-01

    Ion-driven permeation of D through tungsten under simultaneous irradiation with He-D was measured as a function of temperature, flux, and energy. He reduced the permeation flux with the reduction increasing with decreasing temperature. The reduction in permeation flux followed a linear dependence to the incident flux at T > 1000 K, but shifted to a square root dependence at T < 1000 K. The results were interpreted as shifts from diffusion limited to recombination limited H transport according to Doyle and Brice's theory. Arrhenius functions of front diffusivity and recombination coefficients were derived and used to calculate the transport parameter W. The effect of He can be interpreted as changes to the front diffusivity that approaches H diffusion behavior in the absence of traps. The reduction in total concentration results in a shallower concentration gradient that can describe the observed decrease in permeation.

  19. The impact of tritium solubility and diffusivity on inventory and permeation in liquid breeder blankets

    International Nuclear Information System (INIS)

    Caorlin, M.; Gervasini, G.; Reiter, F.

    1988-01-01

    The authors reviewed hydrogen solubility and diffusivity data for liquid lithium-based compounds which are potential breeding blanket materials in NET-type fusion devices. These data have been used to assess tritium permeation and inventory in separately cooled NET blankets and in self cooled blankets with a vanadium first wall. The results for the separately cooled NET-liquid breeder show that tritium permeation is negligible for lithium, a serious problem for Pb-17Li and a critical one for Flibe. The total tritium inventory is lowest in lithium, high in Pb-17Li and very high in Flibe. The high tritium partial pressure for Flibe or Pb-17Li can be reduced in a self cooled blanket with a vanadium first wall. Permeation into the plasma reduces the blanket tritium inventory and permeation. Tritium recovery can be combined with the plasma exhaust

  20. Selective constraint on noncoding regions of hominid genomes.

    Directory of Open Access Journals (Sweden)

    Eliot C Bush

    2005-12-01

    Full Text Available An important challenge for human evolutionary biology is to understand the genetic basis of human-chimpanzee differences. One influential idea holds that such differences depend, to a large extent, on adaptive changes in gene expression. An important step in assessing this hypothesis involves gaining a better understanding of selective constraint on noncoding regions of hominid genomes. In noncoding sequence, functional elements are frequently small and can be separated by large nonfunctional regions. For this reason, constraint in hominid genomes is likely to be patchy. Here we use conservation in more distantly related mammals and amniotes as a way of identifying small sequence windows that are likely to be functional. We find that putatively functional noncoding elements defined in this manner are subject to significant selective constraint in hominids.

  1. Selective Constraint on Noncoding Regions of Hominid Genomes.

    Directory of Open Access Journals (Sweden)

    2005-12-01

    Full Text Available An important challenge for human evolutionary biology is to understand the genetic basis of human-chimpanzee differences. One influential idea holds that such differences depend, to a large extent, on adaptive changes in gene expression. An important step in assessing this hypothesis involves gaining a better understanding of selective constraint on noncoding regions of hominid genomes. In noncoding sequence, functional elements are frequently small and can be separated by large nonfunctional regions. For this reason, constraint in hominid genomes is likely to be patchy. Here we use conservation in more distantly related mammals and amniotes as a way of identifying small sequence windows that are likely to be functional. We find that putatively functional noncoding elements defined in this manner are subject to significant selective constraint in hominids.

  2. Graphical constraints: a graphical user interface for constraint problems

    OpenAIRE

    Vieira, Nelson Manuel Marques

    2015-01-01

    A constraint satisfaction problem is a classical artificial intelligence paradigm characterized by a set of variables (each variable with an associated domain of possible values), and a set of constraints that specify relations among subsets of these variables. Solutions are assignments of values to all variables that satisfy all the constraints. Many real world problems may be modelled by means of constraints. The range of problems that can use this representation is very diverse and embrace...

  3. Recent advances in evolutionary multi-objective optimization

    CERN Document Server

    Datta, Rituparna; Gupta, Abhishek

    2017-01-01

    This book covers the most recent advances in the field of evolutionary multiobjective optimization. With the aim of drawing the attention of up-andcoming scientists towards exciting prospects at the forefront of computational intelligence, the authors have made an effort to ensure that the ideas conveyed herein are accessible to the widest audience. The book begins with a summary of the basic concepts in multi-objective optimization. This is followed by brief discussions on various algorithms that have been proposed over the years for solving such problems, ranging from classical (mathematical) approaches to sophisticated evolutionary ones that are capable of seamlessly tackling practical challenges such as non-convexity, multi-modality, the presence of multiple constraints, etc. Thereafter, some of the key emerging aspects that are likely to shape future research directions in the field are presented. These include:< optimization in dynamic environments, multi-objective bilevel programming, handling high ...

  4. Sex differences in jealousy: evolutionary mechanism or artifact of measurement?

    Science.gov (United States)

    DeSteno, David; Bartlett, Monica Y; Braverman, Julia; Salovey, Peter

    2002-11-01

    Two studies are presented that challenge the evidentiary basis for the existence of evolved sex differences in jealousy. In opposition to the evolutionary view, Study I demonstrated that a sex difference in jealousy resulting from sexual versus emotional infidelity is observed only when judgments are recorded using a forced-choice response format. On all other measures, no sex differences were found; both men and women reported greater jealousy in response to sexual infidelity. A second study revealed that the sex difference on the forced-choice measure disappeared under conditions of cognitive constraint. These findings suggest that the sex difference used to support the evolutionary view of jealousy (e.g., D. M. Buss, R. Larsen, D. Westen, & J. Semmelroth, 1992; D. M. Buss et al., 1999) likely represents a measurement artifact resulting from a format-induced effortful decision strategy and not an automatic, sex-specific response shaped by evolution.

  5. Distance Constraint Satisfaction Problems

    Science.gov (United States)

    Bodirsky, Manuel; Dalmau, Victor; Martin, Barnaby; Pinsker, Michael

    We study the complexity of constraint satisfaction problems for templates Γ that are first-order definable in ({ Z}; {suc}), the integers with the successor relation. Assuming a widely believed conjecture from finite domain constraint satisfaction (we require the tractability conjecture by Bulatov, Jeavons and Krokhin in the special case of transitive finite templates), we provide a full classification for the case that Γ is locally finite (i.e., the Gaifman graph of Γ has finite degree). We show that one of the following is true: The structure Γ is homomorphically equivalent to a structure with a certain majority polymorphism (which we call modular median) and CSP(Γ) can be solved in polynomial time, or Γ is homomorphically equivalent to a finite transitive structure, or CSP(Γ) is NP-complete.

  6. Permeation of macromolecules into the renal glomerular basement membrane and capture by the tubules

    Science.gov (United States)

    Lawrence, Marlon G.; Altenburg, Michael K.; Sanford, Ryan; Willett, Julian D.; Bleasdale, Benjamin; Ballou, Byron; Wilder, Jennifer; Li, Feng; Miner, Jeffrey H.; Berg, Ulla B.; Smithies, Oliver

    2017-01-01

    How the kidney prevents urinary excretion of plasma proteins continues to be debated. Here, using unfixed whole-mount mouse kidneys, we show that fluorescent-tagged proteins and neutral dextrans permeate into the glomerular basement membrane (GBM), in general agreement with Ogston's 1958 equation describing how permeation into gels is related to molecular size. Electron-microscopic analyses of kidneys fixed seconds to hours after injecting gold-tagged albumin, negatively charged gold nanoparticles, and stable oligoclusters of gold nanoparticles show that permeation into the lamina densa of the GBM is size-sensitive. Nanoparticles comparable in size with IgG dimers do not permeate into it. IgG monomer-sized particles permeate to some extent. Albumin-sized particles permeate extensively into the lamina densa. Particles traversing the lamina densa tend to accumulate upstream of the podocyte glycocalyx that spans the slit, but none are observed upstream of the slit diaphragm. At low concentrations, ovalbumin-sized nanoparticles reach the primary filtrate, are captured by proximal tubule cells, and are endocytosed. At higher concentrations, tubular capture is saturated, and they reach the urine. In mouse models of Pierson’s or Alport’s proteinuric syndromes resulting from defects in GBM structural proteins (laminin β2 or collagen α3 IV), the GBM is irregularly swollen, the lamina densa is absent, and permeation is increased. Our observations indicate that size-dependent permeation into the lamina densa of the GBM and the podocyte glycocalyx, together with saturable tubular capture, determines which macromolecules reach the urine without the need to invoke direct size selection by the slit diaphragm. PMID:28246329

  7. Acquisition of Preparative Gel Permeation Chromatography for Research and Education in Energy Conversion and Nanocomposites

    Science.gov (United States)

    2017-04-19

    AFRL-AFOSR-VA-TR-2017-0090 Acquisition of Preparative Gel Permeation Chromatography for Research and Education in Energy Conversion and...TITLE AND SUBTITLE Acquisition of Preparative Gel Permeation Chromatography for Research and Education in Energy Conversion and Nanocomposites 5a... research with education at all levels across a broad range of materials, and create important opportunities to expose and train undergraduates, women

  8. Financial Permeation and Economic Growth: Evidence from Sub-Saharan Africa

    OpenAIRE

    Inoue, Takeshi; Hamori, Shigeyuki

    2013-01-01

    This article empirically analyzes the role of finance in economic growth in Sub-Saharan Africa from the perspective of what is termed herein “financial permeation”. By estimating panel data on 37 countries in Sub-Saharan Africa between 2004 and 2010, we examine whether financial permeation through improved convenience and access to financial services has contributed to economic growth in this region. Empirical results clearly indicate that financial permeation has a statistically significant ...

  9. Catalytic reforming of methane to syngas in an oxygen-permeative membrane reactor

    Energy Technology Data Exchange (ETDEWEB)

    Urano, Takeshi; Kubo, Keiko; Saito, Tomoyuki; Hitomi, Atsushi, E-mail: turano@jp.tdk.com [Materials and Process Development Center, TDK Corporation 570-2, Matsugashita, Minamihatori, Narita, Chiba 286-8588 (Japan)

    2011-05-15

    For fuel cell applications, partial oxidative reforming of methane to syngas, hydrogen and carbon monoxide, was performed via a dense oxygen-permeative ceramic membrane composed by both ionic and electronic conductive materials. The modification of Ni-based catalyst by noble metals was investigated to increase oxygen permeation flux and decrease carbon deposition during reforming reaction. The role of each component in catalyst was also discussed.

  10. Tritium permeation evaluation through vertical target of divertor based on recent tritium transport properties

    International Nuclear Information System (INIS)

    Nakamura, Hirofumi; Nishi, Masataka

    2003-11-01

    Re-evaluation of tritium permeation through vertical target of divertor under the ITER operation condition was carried out using tritium properties in the candidate materials such as the diffusion coefficient and the trapping factors in tungsten for armor, and the surface recombination coefficient on copper for the heat sink obtained by authours' recent investigation (authors' data), which simulated the plasma-facing conditions of ITER. Evaluation with the data set of previous evaluation was also carried out for comparison (previous data). The permeation analysis was carried out individually by classifying into the armor region (Carbon Fiber Composites and tungsten) and the slit region without armor (3% of armor surface area) assuming the incident flux and temperature for each region. As the results of the permeation analysis, estimated permeation amount with the authors' data was one order less than that with the previous data at the end of lifetime of the divertor due to authors' small diffusion coefficient of tritium in tungsten. It also indicated the possibility that permeation through the slit region of the armor tiles could dominate total permeation through the vertical target, since tritium permeation amount through tungsten armor with the authors' data was estimated to be reduced drastically smaller than that with the previous evaluation data. The result of a little tritium permeation amount through the vertical target with the authors' data ensured the conservatism of the current evaluation of tritium concentration in the primary cooling water in ITER divertor, as it indicated the possibility of direct drainage of the divertor primary cooling water. (author)

  11. Enrofloxacin Permeation Pathways across the Porin OmpC.

    Science.gov (United States)

    Prajapati, Jigneshkumar Dahyabhai; Solano, Carlos José Fernández; Winterhalter, Mathias; Kleinekathöfer, Ulrich

    2018-02-01

    In Gram-negative bacteria, the lack or quenching of antibiotic translocation across the outer membrane is one of the main factors for acquiring antibiotic resistance. An atomic-level comprehension of the key features governing the transport of drugs by outer-membrane protein channels would be very helpful in developing the next generation of antibiotics. In a previous study [ J. D. Prajapati et al. J. Chem. Theory Comput. 2017 , 13 , 4553 ], we characterized the diffusion pathway of a ciprofloxacin molecule through the outer membrane porin OmpC of Escherichia coli by combining metadynamics and a zero-temperature string method. Here, we evaluate the diffusion route through the OmpC porin for a similar fluoroquinolone, that is, the enrofloxacin molecule, using the previously developed protocol. As a result, it was found that the lowest-energy pathway was similar to that for ciprofloxacin; namely, a reorientation was required on the extracellular side with the carboxyl group ahead before enrofloxacin reached the constriction region. In turn, the free-energy basins for both antibiotics are located at similar positions in the space defined by selected reaction coordinates, and their affinity sites share a wide number of porin residues. However, there are some important deviations due to the chemical differences of these two drugs. On the one hand, a slower diffusion process is expected for enrofloxacin, as the permeation pathway exhibits higher overall energy barriers, mainly in the constriction region. On the other hand, enrofloxacin needs to replace some polar interactions in its affinity sites with nonpolar ones. This study demonstrates how minor chemical modifications can qualitatively affect the translocation mechanism of an antibiotic molecule.

  12. The Kinetics and the Permeation Properties of Piezo Channels.

    Science.gov (United States)

    Gnanasambandam, R; Gottlieb, P A; Sachs, F

    2017-01-01

    Piezo channels are eukaryotic, cation-selective mechanosensitive channels (MSCs), which show rapid activation and voltage-dependent inactivation. The kinetics of these channels are largely consistent across multiple cell types and different stimulation paradigms with some minor variability. No accessory subunits that associate with Piezo channels have been reported. They are homotrimers and each ∼300kD monomer has an N-terminal propeller blade-like mechanosensing module, which can confer mechanosensing capabilities on ASIC-1 (the trimeric non-MSC, acid-sensing ion channel-1) and a C-terminal pore module, which influences conductance, selectivity, and channel inactivation. Repeated stimulation can cause domain fracture and diffusion of these channels leading to synchronous loss of inactivation. The reconstituted channels spontaneously open only in asymmetric bilayers but lack inactivation. Mutations that cause hereditary xerocytosis alter PIEZO1 kinetics. The kinetics of the wild-type PIEZO1 and alterations thereof in mutants (M2225R, R2456K, and DhPIEZO1) are summarized in the form of a quantitative model and hosted online. The pore is permeable to alkali ions although Li + permeates poorly. Divalent cations, notably Ca 2+ , traverse the channel and inhibit the flux of monovalents. The large monovalent organic cations such as tetramethyl ammonium and tetraethyl ammonium can traverse the channel, but slowly, suggesting a pore diameter of ∼8Å, and the estimated in-plane area change upon opening is around 6-20nm 2 . Ruthenium red can enter the channel only from the extracellular side and seems to bind in a pocket close to residue 2496. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Constraint-based scheduling

    Science.gov (United States)

    Zweben, Monte

    1993-01-01

    The GERRY scheduling system developed by NASA Ames with assistance from the Lockheed Space Operations Company, and the Lockheed Artificial Intelligence Center, uses a method called constraint-based iterative repair. Using this technique, one encodes both hard rules and preference criteria into data structures called constraints. GERRY repeatedly attempts to improve schedules by seeking repairs for violated constraints. The system provides a general scheduling framework which is being tested on two NASA applications. The larger of the two is the Space Shuttle Ground Processing problem which entails the scheduling of all the inspection, repair, and maintenance tasks required to prepare the orbiter for flight. The other application involves power allocation for the NASA Ames wind tunnels. Here the system will be used to schedule wind tunnel tests with the goal of minimizing power costs. In this paper, we describe the GERRY system and its application to the Space Shuttle problem. We also speculate as to how the system would be used for manufacturing, transportation, and military problems.

  14. Synonymous genes explore different evolutionary landscapes.

    Directory of Open Access Journals (Sweden)

    Guillaume Cambray

    2008-11-01

    Full Text Available The evolutionary potential of a gene is constrained not only by the amino acid sequence of its product, but by its DNA sequence as well. The topology of the genetic code is such that half of the amino acids exhibit synonymous codons that can reach different subsets of amino acids from each other through single mutation. Thus, synonymous DNA sequences should access different regions of the protein sequence space through a limited number of mutations, and this may deeply influence the evolution of natural proteins. Here, we demonstrate that this feature can be of value for manipulating protein evolvability. We designed an algorithm that, starting from an input gene, constructs a synonymous sequence that systematically includes the codons with the most different evolutionary perspectives; i.e., codons that maximize accessibility to amino acids previously unreachable from the template by point mutation. A synonymous version of a bacterial antibiotic resistance gene was computed and synthesized. When concurrently submitted to identical directed evolution protocols, both the wild type and the recoded sequence led to the isolation of specific, advantageous phenotypic variants. Simulations based on a mutation isolated only from the synthetic gene libraries were conducted to assess the impact of sub-functional selective constraints, such as codon usage, on natural adaptation. Our data demonstrate that rational design of synonymous synthetic genes stands as an affordable improvement to any directed evolution protocol. We show that using two synonymous DNA sequences improves the overall yield of the procedure by increasing the diversity of mutants generated. These results provide conclusive evidence that synonymous coding sequences do experience different areas of the corresponding protein adaptive landscape, and that a sequence's codon usage effectively constrains the evolution of the encoded protein.

  15. Does the evolutionary conservation of microsatellite loci imply function?

    Energy Technology Data Exchange (ETDEWEB)

    Shriver, M.D.; Deka, R.; Ferrell, R.E. [Univ. of Pittsburgh, PA (United States)] [and others

    1994-09-01

    Microsatellites are highly polymorphic tandem arrays of short (1-6 bp) sequence motifs which have been found widely distributed in the genomes of all eukaryotes. We have analyzed allele frequency data on 16 microsatellite loci typed in the great apes (human, chimp, orangutan, and gorilla). The majority of these loci (13) were isolated from human genomic libraries; three were cloned from chimpanzee genomic DNA. Most of these loci are not only present in all apes species, but are polymorphic with comparable levels of heterozygosity and have alleles which overlap in size. The extent of divergence of allele frequencies among these four species were studies using the stepwise-weighted genetic distance (Dsw), which was previously shown to conform to linearity with evolutionary time since divergence for loci where mutations exist in a stepwise fashion. The phylogenetic tree of the great apes constructed from this distance matrix was consistent with the expected topology, with a high bootstrap confidence (82%) for the human/chimp clade. However, the allele frequency distributions of these species are 10 times more similar to each other than expected when they were calibrated with a conservative estimate of the time since separation of humans and the apes. These results are in agreement with sequence-based surveys of microsatellites which have demonstrated that they are highly (90%) conserved over short periods of evolutionary time (< 10 million years) and moderately (30%) conserved over long periods of evolutionary time (> 60-80 million years). This evolutionary conservation has prompted some authors to speculate that there are functional constraints on microsatellite loci. In contrast, the presence of directional bias of mutations with constraints and/or selection against aberrant sized alleles can explain these results.

  16. A comparison of implantation-driven permeation characteristics of fusion reactor structural materials

    Science.gov (United States)

    Longhurst, G. R.; Anderl, R. A.; Struttmann, D. A.

    1986-11-01

    Implantation-driven permeation experiments have been conducted on samples of the ferritic steel HT-9, the austenitic Primary Candidate Alloy (PCA) and the vanadium alloy V-15Cr-5Ti using D 3+ ions under conditions that simulate charge-exchange neutral loading on a fusion reactor first wall. The steels all exhibited an initially intense permeation "spike" followed by an exponential decrease to low steady-state values. That spike was not evident in the V-15Cr-5Ti experiments. Steady-state permeation was highest in the vanadium alloy and lowest in the austenitic steel. Though permeation rates in the HT-9 were lower than those in V-15Cr-5Ti, permeation transients were much faster in HT-9 than in other materials tested. Sputtering of the steel surface resulted in enhanced reemission, whereas in the vanadium tests, recombination and diffusivity both appeared to diminish as the deuterium concentration rose. We conclude that for conditions comparable to those of these experiments, tritium retention and permeation loss in first wall structures made of steels will be less than in structures made of V-15Cr-5Ti.

  17. Comparison on implantation-driven permeation characteristics of fusion reactor structural materials

    Energy Technology Data Exchange (ETDEWEB)

    Longhurst, G.R.; Anderl, R.A.; Struttmann, D.A. (Idaho National Engineering Lab., Idaho Falls)

    Implantation-driven permeation experiments have been conducted on samples of the ferritic steel HT-9, the austenitic Primary Candidate Alloy (PCA) and the vanadium alloy V-15Cr-5Ti using D{sub 3}{sup +} ions under conditions that simulate charge-exchange neutral loading on a fusion reactor first wall. The steels all exhibited an initially intense permeation spike followed by an exponential decrease to low steady-state values. That spike was not evident in the V-15Cr-5Ti experiments. Steady-state permeation was highest in the vanadium alloy and lowest in the austenitic steel. Though permeation rates in the HT-9 were lower than those in V-15Cr-5Ti, permeation transients were much faster in HT-9 than in other materials tested. Sputtering of the steel surface resulted in enhanced reemission, whereas in the vanadium tests, recombination and diffusivity both appeared to diminish as the deuterium concentration rose. We conclude that for conditions comparable to those of these experiments, tritium retention and permeation loss in first wall structures made of steels will be less than in structures made of V-15Cr-5Ti.

  18. Effects of Vehicles and Enhancers on the Skin Permeation of Phytoestrogenic Diarylheptanoids from Curcuma comosa.

    Science.gov (United States)

    Tuntiyasawasdikul, Sarunya; Limpongsa, Ekapol; Jaipakdee, Napaphak; Sripanidkulchai, Bungorn

    2017-04-01

    Curcuma comosa (C. comosa) is widely used in traditional medicine as a dietary supplement for health promotion in postmenopausal women in Thailand. It contains several diarylheptanoids, which are considered to be a novel class of phytoestrogens. However, the diarylheptanoids isolated from the plant rhizome are shown to have low oral bioavailability and faster elimination characteristics. The aim of this study was to investigate the permeation behavior of the active compounds of diarylheptanoids. The effects of binary vehicle systems and permeation enhancers on diarylheptanoids permeation and accumulation within the skin were studied using side-by-side diffusion cells through the porcine ear skin. Among the tested binary vehicle systems, the ethanol/water vehicle appeared to be the most effective system for diarylheptanoids permeation with the highest flux and shortest lag time. The presence of transcutol in the vehicle system significantly increased diarylheptanoid's permeation and accumulation within the skin in a concentration-dependent manner. Although the presence of terpenes in formulation decreased the flux of diarylheptanoids, it raised the amount of diarylheptanoids retained within the skin substantially. Based on the feasibility of diarylheptanoid permeation, C. comosa extract should be further developed into an effective transdermal product for health benefits and hormone replacement therapy.

  19. Compensation effect in H 2 permeation kinetics of PdAg membranes

    KAUST Repository

    Zeng, Gaofeng

    2012-08-30

    Knowledge about the (inter)dependence of permeation kinetic parameters on the stoichiometry of H 2-selective alloys is still rudimentary, although uncovering the underlying systematic correlations will greatly facilitate current efforts into the design of novel high-performance H 2 separation membranes. Permeation measurements with carefully engineered, 2-7 μm thick supported Pd 100-xAg x membranes reveal that the activation energy and pre-exponential factor of H 2 permeation laws vary systematically with alloy composition, and both kinetic parameters are strongly correlated for x ≤ 50. We show that this permeation kinetic compensation effect corresponds well with similar correlations in the hydrogen solution thermodynamics and diffusion kinetics of PdAg alloys that govern H 2 permeation rates. This effect enables the consistent description of permeation characteristics over wide temperature and alloy stoichiometry ranges, whereas hydrogen solution thermodynamics may play a role, too, as a yet unrecognized source of kinetic compensation in, for example, H 2-involving reactions over metal catalysts or hydrogenation/ dehydrogenation of hydrogen storage materials. © 2012 American Chemical Society.

  20. Enhanced skin permeation of naltrexone by pulsed electromagnetic fields in human skin in vitro.

    Science.gov (United States)

    Krishnan, Gayathri; Edwards, Jeffrey; Chen, Yan; Benson, Heather A E

    2010-06-01

    The aim of the present study was to evaluate the skin permeation of naltrexone (NTX) under the influence of a pulsed electromagnetic field (PEMF). The permeation of NTX across human epidermis and a silicone membrane in vitro was monitored during and after application of the PEMF and compared to passive application. Enhancement ratios of NTX human epidermis permeation by PEMF over passive diffusion, calculated based on the AUC of cumulative NTX permeation to the receptor compartment verses time for 0-4 h, 4-8 h, and over the entire experiment (0-8 h) were 6.52, 5.25, and 5.66, respectively. Observation of the curve indicated an initial enhancement of NTX permeation compared to passive delivery whilst the PEMF was active (0-4 h). This was followed by a secondary phase after termination of PEMF energy (4-8 h) in which there was a steady increase in NTX permeation. No significant enhancement of NTX penetration across silicone membrane occurred with PEMF application in comparison to passively applied NTX. In a preliminary experiment PEMF enhanced the penetration of 10 nm gold nanoparticles through the stratum corneum as visualized by multiphoton microscopy. This suggests that the channels through which the nanoparticles move must be larger than the 10 nm diameter of these rigid particles. (c) 2009 Wiley-Liss, Inc. and the American Pharmacists Association

  1. Differential permeation of piroxicam-loaded PLGA micro/nanoparticles and their in vitro enhancement

    International Nuclear Information System (INIS)

    Shankarayan, Raju; Kumar, Sumit; Mishra, Prashant

    2013-01-01

    Piroxicam is a non-steroidal anti-inflammatory drug used for the treatment of musculoskeletal pain. The main problem encountered when piroxicam is administered orally is its gastric side-effect (ulcer, bleeding and holes in the stomach). Transmucosal delivery and encapsulation of piroxicam in biodegradable particles offer potential advantages over conventional oral delivery. The present study was aimed to develop an alternative to piroxicam-delivery which could overcome the direct contact of the drug at the mucosal membrane and its permeation through the mucosal membrane was studied. To achieve this, the piroxicam was encapsulated in Poly (lactide-co-glycolide) (PLGA) microparticles (size 1–4 μm, encapsulation efficiency 80–85 %) and nanoparticles (size 151.6 ± 28.6 nm, encapsulation efficiency 92.17 ± 3.08 %). Various formulation process parameters were optimised for the preparation of piroxicam-loaded PLGA nanoparticles of optimal size and encapsulation efficiency. Transmucosal permeability of piroxicam-loaded PLGA micro- and nanoparticles through the porcine oesophageal mucosa was studied. Using fluorescently labelled PLGA micro- and nanoparticles, size-dependent permeation was demonstrated. Furthermore, the effect of different permeation enhancers on the flux rate and permeability coefficient for the permeation of nanoparticles was investigated. The results suggested that amongst the permeation enhancers used the most efficient enhancement of permeation was observed with 10 mM sodium dodecyl sulphate.

  2. Differential permeation of piroxicam-loaded PLGA micro/nanoparticles and their in vitro enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Shankarayan, Raju; Kumar, Sumit; Mishra, Prashant, E-mail: pmishra@dbeb.iitd.ac.in [Indian Institute of Technology Delhi, Department of Biochemical Engineering and Biotechnology (India)

    2013-03-15

    Piroxicam is a non-steroidal anti-inflammatory drug used for the treatment of musculoskeletal pain. The main problem encountered when piroxicam is administered orally is its gastric side-effect (ulcer, bleeding and holes in the stomach). Transmucosal delivery and encapsulation of piroxicam in biodegradable particles offer potential advantages over conventional oral delivery. The present study was aimed to develop an alternative to piroxicam-delivery which could overcome the direct contact of the drug at the mucosal membrane and its permeation through the mucosal membrane was studied. To achieve this, the piroxicam was encapsulated in Poly (lactide-co-glycolide) (PLGA) microparticles (size 1-4 {mu}m, encapsulation efficiency 80-85 %) and nanoparticles (size 151.6 {+-} 28.6 nm, encapsulation efficiency 92.17 {+-} 3.08 %). Various formulation process parameters were optimised for the preparation of piroxicam-loaded PLGA nanoparticles of optimal size and encapsulation efficiency. Transmucosal permeability of piroxicam-loaded PLGA micro- and nanoparticles through the porcine oesophageal mucosa was studied. Using fluorescently labelled PLGA micro- and nanoparticles, size-dependent permeation was demonstrated. Furthermore, the effect of different permeation enhancers on the flux rate and permeability coefficient for the permeation of nanoparticles was investigated. The results suggested that amongst the permeation enhancers used the most efficient enhancement of permeation was observed with 10 mM sodium dodecyl sulphate.

  3. Differential permeation of piroxicam-loaded PLGA micro/nanoparticles and their in vitro enhancement

    Science.gov (United States)

    Shankarayan, Raju; Kumar, Sumit; Mishra, Prashant

    2013-03-01

    Piroxicam is a non-steroidal anti-inflammatory drug used for the treatment of musculoskeletal pain. The main problem encountered when piroxicam is administered orally is its gastric side-effect (ulcer, bleeding and holes in the stomach). Transmucosal delivery and encapsulation of piroxicam in biodegradable particles offer potential advantages over conventional oral delivery. The present study was aimed to develop an alternative to piroxicam-delivery which could overcome the direct contact of the drug at the mucosal membrane and its permeation through the mucosal membrane was studied. To achieve this, the piroxicam was encapsulated in Poly (lactide- co-glycolide) (PLGA) microparticles (size 1-4 μm, encapsulation efficiency 80-85 %) and nanoparticles (size 151.6 ± 28.6 nm, encapsulation efficiency 92.17 ± 3.08 %). Various formulation process parameters were optimised for the preparation of piroxicam-loaded PLGA nanoparticles of optimal size and encapsulation efficiency. Transmucosal permeability of piroxicam-loaded PLGA micro- and nanoparticles through the porcine oesophageal mucosa was studied. Using fluorescently labelled PLGA micro- and nanoparticles, size-dependent permeation was demonstrated. Furthermore, the effect of different permeation enhancers on the flux rate and permeability coefficient for the permeation of nanoparticles was investigated. The results suggested that amongst the permeation enhancers used the most efficient enhancement of permeation was observed with 10 mM sodium dodecyl sulphate.

  4. High permeation rates in liposome systems explain rapid glyphosate biodegradation associated with strong isotope fractionation.

    Science.gov (United States)

    Ehrl, Benno; Mogusu, Emmanuel O; Kim, Kyoungtea; Hofstetter, Heike; Pedersen, Joel A; Elsner, Martin

    2018-05-23

    Bacterial uptake of charged organic pollutants such as the widely used herbicide glyphosate is typically attributed to active transporters, whereas passive membrane permeation as an uptake pathway is usually neglected. For 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) liposomes, pH-dependent membrane permeation coefficients (Papp) of glyphosate, determined by nuclear magnetic resonance (NMR) spectroscopy, varied from Papp(pH 7.0) = 3.7 (+/-0.3) × 10-7 m∙s-1 to Papp(pH 4.1) = 4.2 (+/-0.1) × 10-6 m∙s-1. This surprisingly rapid membrane permeation depended on glyphosate speciation and was, at physiological pH, in the range of polar, non-charged molecules suggesting that passive membrane permeation is a potential uptake pathway during glyphosate biodegradation. To test this hypothesis, a Gram-negative glyphosate degrader, Ochrobactrum sp. FrEM, was isolated from glyphosate-treated soil and glyphosate permeation rates inferred from the liposome model were compared to bacterial degradation rates. Estimated maximum permeation rates were, indeed, two orders of magnitudes higher than glyphosate degradation rates. Moreover, biodegradation of millimolar glyphosate concentrations gave rise to pronounced carbon isotope fractionation with an apparent kinetic isotope effect of AKIEcarbon= 1.014 ± 0.003. This value is consistent with unmasked enzymatic isotope fractionation demonstrating that glyphosate biodegradation was little mass transfer-limited and glyphosate exchange across the cell membrane was rapid relative to enzymatic turnover.

  5. Hydrogen permeation modification of 4140 steel by ion nitriding with pulsed plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Bruzzoni, P.; Ortiz, M. [Comision Nacional de Energia Atomica, Buenos Aires (Argentina); Bruehl, S.P.; Gomez, B.J.A.; Feugeas, J.N. [Inst. de Fisica Rosario (UNR-CONICET), Rosario (Argentina); Nosei, L. [Inst. de Mecanica Aplicada y Estructuras (UNR), Rosario (Argentina)

    1998-11-10

    It is widely known that the hydrogen in steel produces embrittlement. This effect may cause the failure of the elements (confining walls, mechanical parts, etc.) whose surfaces are in contact with this gas or with processes in which hydrogen is continuously generated. In this work it is shown that the ion nitriding of the surface of AISI 4140 is a good mechanism to act as a barrier against hydrogen permeation in its bulk. The ion nitriding was performed using a square wave DC glow discharge. The development of a compound layer of iron nitrides was observed as the cause of the hydrogen permeation reduction. For equal duration of treatment, thicker compound layers were developed in higher discharge/post-discharge ratios in the square wave of the applied voltage onto the sample (cathode), with a greater reduction of hydrogen permeation coefficient as a consequence. Nevertheless, the permeation was not reduced to zero in any of the treatment conditions used. The results of the analysis of the permeation tests and the image of the photomicrographs showed that the existence of cracks, fractures, failures, etc. in the compound layer (pre-existing in the AISI 4140 steel) could be the cause of the residual hydrogen permeation. This can be attributed to the movement of the hydrogen through these defects diffusing through the original {alpha}-Fe phase of the non-treated steel. (orig.) 11 refs.

  6. Skin permeation of D-limonene-based nanoemulsions as a transdermal carrier prepared by ultrasonic emulsification.

    Science.gov (United States)

    Lu, Wen-Chien; Chiang, Been-Huang; Huang, Da-Wei; Li, Po-Hsien

    2014-03-01

    Nanoemulsions can be used for transporting pharmaceutical phytochemicals in skin-care products because of their stability and rapid permeation properties. However, droplet size may be a critical factor aiding permeation through skin and transdermal delivery efficiency. We prepared D-limonene nanoemulsions with various droplet sizes by ultrasonic emulsification using mixed surfactants of sorbitane trioleate and polyoxyethylene (20) oleyl ether under different hydrophilic-lipophilic balance (HLB) values. Droplet size decreased with increasing HLB value. With HLB 12, the droplet size was 23 nm, and the encapsulated ratio peaked at 92.3%. Transmission electron microscopy revealed spherical droplets and the gray parts were D-limonene precipitation incorporated in spherical droplets of the emulsion system. Franz diffusion cell was used to evaluate the permeation of D-limonene nanoemulsion through rat abdominal skin; the permeation rate depended on droplet size. The emulsion with the lowest droplet size (54 nm) achieved the maximum permeation rate. The concentration of D-limonene in the skin was 40.11 μL/cm(2) at the end of 360 min. Histopathology revealed no distinct voids or empty spaces in the epidermal region of permeated rat skin, so the D-limonene nanoemulsion may be a safe carrier for transdermal drug delivery. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Crystallization and deuterium permeation behaviors of yttrium oxide coating prepared by metal organic decomposition

    Directory of Open Access Journals (Sweden)

    Takumi Chikada

    2016-12-01

    Full Text Available Yttrium oxide coatings were fabricated on reduced activation ferritic/martensitic steels by metal organic decomposition with a dip-coating technique, and their deuterium permeation behaviors were investigated. The microstructure of the coatings varied with heat-treatment temperature: amorphous at 670ºC (amorphous coating and crystallized at 700ºC (crystallized coating. Deuterium permeation flux of the amorphous coating was lower than the uncoated steel by a factor of 5 at 500ºC, while that of the crystallized coating was lower by a factor of around 100 at 400‒550ºC. The permeation fluxes of both coatings were drastically decreased during the measurements at higher temperatures by a factor of up to 790 for the amorphous coating and 1000 for the crystallized one, indicating a microstructure modification occurred by an effect of test temperature with hydrogen flux. Temperature dependence of deuterium diffusivity in the coatings suggests that the decrease of the permeation flux has been derived from a decrease of the diffusivity. Characteristic permeation behaviors were observed with different annealing conditions; however, they can be interpreted using the permeation mechanism clarified in the previous erbium oxide coating studies.

  8. Changes on iron electrode surface during hydrogen permeation in borate buffer solution

    International Nuclear Information System (INIS)

    Modiano, S.; Carreno, J.A.V.; Fugivara, C.S.; Torresi, R.M.; Vivier, V.; Benedetti, A.V.; Mattos, O.R.

    2008-01-01

    Hydrogen interaction with oxide films grown on iron electrodes at open circuit potential (E oc ) and in the passive region (+0.30 V ECS ) was studied by chronopotentiometry, chronoamperometry and electrochemical impedance spectroscopy techniques. The results were obtained in deaerated 0.3 mol L -1 H 3 BO 3 + 0.075 mol L -1 Na 2 B 4 O 7 (BB, pH 8.4) solution before, during and after hydrogen permeation. The iron oxide film modification was also investigated by means of in situ X-ray absorption near-edge spectroscopy (XANES) and scanning electrochemical microscopy (SECM) before and during hydrogen permeation. The main conclusion was that the passive film is reduced during the hydrogen diffusion. The hydrogen permeation stabilizes the iron surface at a potential close to the thermodynamic water stability line where hydrogen evolution can occur. The stationary condition required for the determination of the permeation parameters cannot be easily attained on iron surface during hydrogen permeation. Moreover, additional attention must be paid when obtaining the transport parameters using the classical permeation cell

  9. Evolutionary foundations for cancer biology.

    Science.gov (United States)

    Aktipis, C Athena; Nesse, Randolph M

    2013-01-01

    New applications of evolutionary biology are transforming our understanding of cancer. The articles in this special issue provide many specific examples, such as microorganisms inducing cancers, the significance of within-tumor heterogeneity, and the possibility that lower dose chemotherapy may sometimes promote longer survival. Underlying these specific advances is a large-scale transformation, as cancer research incorporates evolutionary methods into its toolkit, and asks new evolutionary questions about why we are vulnerable to cancer. Evolution explains why cancer exists at all, how neoplasms grow, why cancer is remarkably rare, and why it occurs despite powerful cancer suppression mechanisms. Cancer exists because of somatic selection; mutations in somatic cells result in some dividing faster than others, in some cases generating neoplasms. Neoplasms grow, or do not, in complex cellular ecosystems. Cancer is relatively rare because of natural selection; our genomes were derived disproportionally from individuals with effective mechanisms for suppressing cancer. Cancer occurs nonetheless for the same six evolutionary reasons that explain why we remain vulnerable to other diseases. These four principles-cancers evolve by somatic selection, neoplasms grow in complex ecosystems, natural selection has shaped powerful cancer defenses, and the limitations of those defenses have evolutionary explanations-provide a foundation for understanding, preventing, and treating cancer.

  10. An Evolutionary Optimization Framework for Neural Networks and Neuromorphic Architectures

    Energy Technology Data Exchange (ETDEWEB)

    Schuman, Catherine D [ORNL; Plank, James [University of Tennessee (UT); Disney, Adam [University of Tennessee (UT); Reynolds, John [University of Tennessee (UT)

    2016-01-01

    As new neural network and neuromorphic architectures are being developed, new training methods that operate within the constraints of the new architectures are required. Evolutionary optimization (EO) is a convenient training method for new architectures. In this work, we review a spiking neural network architecture and a neuromorphic architecture, and we describe an EO training framework for these architectures. We present the results of this training framework on four classification data sets and compare those results to other neural network and neuromorphic implementations. We also discuss how this EO framework may be extended to other architectures.

  11. Efficient Searching with Linear Constraints

    DEFF Research Database (Denmark)

    Agarwal, Pankaj K.; Arge, Lars Allan; Erickson, Jeff

    2000-01-01

    We show how to preprocess a set S of points in d into an external memory data structure that efficiently supports linear-constraint queries. Each query is in the form of a linear constraint xd a0+∑d−1i=1 aixi; the data structure must report all the points of S that satisfy the constraint. This pr...

  12. Deepening Contractions and Collateral Constraints

    DEFF Research Database (Denmark)

    Jensen, Henrik; Ravn, Søren Hove; Santoro, Emiliano

    and occasionally non-binding credit constraints. Easier credit access increases the likelihood that constraints become slack in the face of expansionary shocks, while contractionary shocks are further amplified due to tighter constraints. As a result, busts gradually become deeper than booms. Based...

  13. A New DG Multiobjective Optimization Method Based on an Improved Evolutionary Algorithm

    Directory of Open Access Journals (Sweden)

    Wanxing Sheng

    2013-01-01

    Full Text Available A distribution generation (DG multiobjective optimization method based on an improved Pareto evolutionary algorithm is investigated in this paper. The improved Pareto evolutionary algorithm, which introduces a penalty factor in the objective function constraints, uses an adaptive crossover and a mutation operator in the evolutionary process and combines a simulated annealing iterative process. The proposed algorithm is utilized to the optimize DG injection models to maximize DG utilization while minimizing system loss and environmental pollution. A revised IEEE 33-bus system with multiple DG units was used to test the multiobjective optimization algorithm in a distribution power system. The proposed algorithm was implemented and compared with the strength Pareto evolutionary algorithm 2 (SPEA2, a particle swarm optimization (PSO algorithm, and nondominated sorting genetic algorithm II (NGSA-II. The comparison of the results demonstrates the validity and practicality of utilizing DG units in terms of economic dispatch and optimal operation in a distribution power system.

  14. A permeation theory for single-file ion channels: one- and two-step models.

    Science.gov (United States)

    Nelson, Peter Hugo

    2011-04-28

    How many steps are required to model permeation through ion channels? This question is investigated by comparing one- and two-step models of permeation with experiment and MD simulation for the first time. In recent MD simulations, the observed permeation mechanism was identified as resembling a Hodgkin and Keynes knock-on mechanism with one voltage-dependent rate-determining step [Jensen et al., PNAS 107, 5833 (2010)]. These previously published simulation data are fitted to a one-step knock-on model that successfully explains the highly non-Ohmic current-voltage curve observed in the simulation. However, these predictions (and the simulations upon which they are based) are not representative of real channel behavior, which is typically Ohmic at low voltages. A two-step association/dissociation (A/D) model is then compared with experiment for the first time. This two-parameter model is shown to be remarkably consistent with previously published permeation experiments through the MaxiK potassium channel over a wide range of concentrations and positive voltages. The A/D model also provides a first-order explanation of permeation through the Shaker potassium channel, but it does not explain the asymmetry observed experimentally. To address this, a new asymmetric variant of the A/D model is developed using the present theoretical framework. It includes a third parameter that represents the value of the "permeation coordinate" (fractional electric potential energy) corresponding to the triply occupied state n of the channel. This asymmetric A/D model is fitted to published permeation data through the Shaker potassium channel at physiological concentrations, and it successfully predicts qualitative changes in the negative current-voltage data (including a transition to super-Ohmic behavior) based solely on a fit to positive-voltage data (that appear linear). The A/D model appears to be qualitatively consistent with a large group of published MD simulations, but no

  15. Evolutionary engineering for industrial microbiology.

    Science.gov (United States)

    Vanee, Niti; Fisher, Adam B; Fong, Stephen S

    2012-01-01

    Superficially, evolutionary engineering is a paradoxical field that balances competing interests. In natural settings, evolution iteratively selects and enriches subpopulations that are best adapted to a particular ecological niche using random processes such as genetic mutation. In engineering desired approaches utilize rational prospective design to address targeted problems. When considering details of evolutionary and engineering processes, more commonality can be found. Engineering relies on detailed knowledge of the problem parameters and design properties in order to predict design outcomes that would be an optimized solution. When detailed knowledge of a system is lacking, engineers often employ algorithmic search strategies to identify empirical solutions. Evolution epitomizes this iterative optimization by continuously diversifying design options from a parental design, and then selecting the progeny designs that represent satisfactory solutions. In this chapter, the technique of applying the natural principles of evolution to engineer microbes for industrial applications is discussed to highlight the challenges and principles of evolutionary engineering.

  16. Evolutionary Aesthetics and Print Advertising

    Directory of Open Access Journals (Sweden)

    Kamil Luczaj

    2015-06-01

    Full Text Available The article analyzes the extent to which predictions based on the theory of evolutionary aesthetics are utilized by the advertising industry. The purpose of a comprehensive content analysis of print advertising is to determine whether the items indicated by evolutionists such as animals, flowers, certain types of landscapes, beautiful humans, and some colors are part of real advertising strategies. This article has shown that many evolutionary hypotheses (although not all of them are supported by empirical data. Along with these hypotheses, some inferences from Bourdieu’s cultural capital theory were tested. It turned out that advertising uses both biological schemata and cultural patterns to make an image more likable.

  17. The evolutionary psychology of hunger.

    Science.gov (United States)

    Al-Shawaf, Laith

    2016-10-01

    An evolutionary psychological perspective suggests that emotions can be understood as coordinating mechanisms whose job is to regulate various psychological and physiological programs in the service of solving an adaptive problem. This paper suggests that it may also be fruitful to approach hunger from this coordinating mechanism perspective. To this end, I put forward an evolutionary task analysis of hunger, generating novel a priori hypotheses about the coordinating effects of hunger on psychological processes such as perception, attention, categorization, and memory. This approach appears empirically fruitful in that it yields a bounty of testable new hypotheses. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Diversity-Guided Evolutionary Algorithms

    DEFF Research Database (Denmark)

    Ursem, Rasmus Kjær

    2002-01-01

    Population diversity is undoubtably a key issue in the performance of evolutionary algorithms. A common hypothesis is that high diversity is important to avoid premature convergence and to escape local optima. Various diversity measures have been used to analyze algorithms, but so far few...... algorithms have used a measure to guide the search. The diversity-guided evolutionary algorithm (DGEA) uses the wellknown distance-to-average-point measure to alternate between phases of exploration (mutation) and phases of exploitation (recombination and selection). The DGEA showed remarkable results...

  19. On the evolutionary relationship between chondrocytes and osteoblasts

    Directory of Open Access Journals (Sweden)

    Patsy eGomez-Picos

    2015-09-01

    Full Text Available Vertebrates are the only animals that produce bone, but the molecular genetic basis for this evolutionary novelty remains obscure. Here, we synthesize information from traditional evolutionary and modern molecular genetic studies in order to generate a working hypothesis on the evolution of the gene regulatory network (GRN underlying bone formation. To make this argument, we focus on three skeletal tissues that comprise the majority of the vertebrate skeleton: immature cartilage, mature cartilage, and bone. Immature cartilage is produced during early stages of cartilage differentiation and can persist into adulthood, whereas mature cartilage undergoes additional stages of differentiation, including hypertrophy and mineralization. Functionally, histologically, and embryologically, these three skeletal tissues are very similar, yet unique, suggesting that one might have evolved from another. Traditional studies of the fossil record, comparative anatomy and embryology demonstrate clearly that immature cartilage evolved before mature cartilage or bone. Modern molecular approaches show that the GRNs regulating differentiation of these three skeletal cell fates are similar, yet unique, just like the functional and histological features of the tissues themselves. Intriguingly, the Sox9 GRN driving cartilage formation appears to be dominant to the Runx2 GRN of bone. Emphasizing an embryological and evolutionary transcriptomic view, we hypothesize that the Runx2 GRN underlying bone formation was co-opted from mature cartilage. We discuss how modern molecular genetic experiments, such as comparative transcriptomics, can test this hypothesis directly, meanwhile permitting levels of constraint and adaptation to be evaluated quantitatively. Therefore, comparative transcriptomics may revolutionize understanding of not only the clade-specific evolution of skeletal cells, but also the generation of evolutionary novelties, providing a modern paradigm for the

  20. Expansion of thermodynamic model of solute permeation through reverse osmosis membrane

    International Nuclear Information System (INIS)

    Nishimaki, Kenzo; Koyama, Akio

    1994-01-01

    Many studies have been performed on permeation mechanism of solute and solvent in membrane separation process like reverse osmosis or ultrafiltration, and several models of solute/solvent permeation through membrane are proposed. Among these models, Kedem and Katchalsky, based on the theory of thermodynamics of irreversible processes, formulated the one-solute permeation process in their mathematical model, which treats membrane as a black box, not giving consideration to membrane structure and to interaction between membrane material and permeates, viz. solute and solvent. According to this theory, the driving force of solute/solvent permeation through membrane is the difference of their chemical potential between both sides of membrane, and the linear phenomenological equation is applied to describing the relation between driving force and flux of solute/solvent. This equation can be applied to the irreversible process only when the process is almost in equilibrium. This condition is supposed to be satisfied in the solute/solvent permeation process through compact membrane with fine pores like reverse osmosis membrane. When reverse osmosis is applied to treatment process for liquid waste, which usually contains a lot of solutes as contaminants, we can not predict the behavior of contaminants by the above one-solute process model. In the case of multi-solutes permeation process for liquid waste, the number of parameter in thermodynamic model increases rapidly with the number of solute, because of coupling phenomenon among solutes. In this study, we expanded the above thermodynamic model to multi-solute process applying operational calculus to the differential equations which describe the irreversible process of the system, and expressed concisely solute concentration vector as a matrix product. In this way, we predict the behavior of solutes in multi-solutes process, using values of parameters obtained in two-solutes process. (author)

  1. Design with Nonlinear Constraints

    KAUST Repository

    Tang, Chengcheng

    2015-12-10

    Most modern industrial and architectural designs need to satisfy the requirements of their targeted performance and respect the limitations of available fabrication technologies. At the same time, they should reflect the artistic considerations and personal taste of the designers, which cannot be simply formulated as optimization goals with single best solutions. This thesis aims at a general, flexible yet e cient computational framework for interactive creation, exploration and discovery of serviceable, constructible, and stylish designs. By formulating nonlinear engineering considerations as linear or quadratic expressions by introducing auxiliary variables, the constrained space could be e ciently accessed by the proposed algorithm Guided Projection, with the guidance of aesthetic formulations. The approach is introduced through applications in different scenarios, its effectiveness is demonstrated by examples that were difficult or even impossible to be computationally designed before. The first application is the design of meshes under both geometric and static constraints, including self-supporting polyhedral meshes that are not height fields. Then, with a formulation bridging mesh based and spline based representations, the application is extended to developable surfaces including origami with curved creases. Finally, general approaches to extend hard constraints and soft energies are discussed, followed by a concluding remark outlooking possible future studies.

  2. Searching for genomic constraints

    Energy Technology Data Exchange (ETDEWEB)

    Lio` , P [Cambridge, Univ. (United Kingdom). Genetics Dept.; Ruffo, S [Florence, Univ. (Italy). Fac. di Ingegneria. Dipt. di Energetica ` S. Stecco`

    1998-01-01

    The authors have analyzed general properties of very long DNA sequences belonging to simple and complex organisms, by using different correlation methods. They have distinguished those base compositional rules that concern the entire genome which they call `genomic constraints` from the rules that depend on the `external natural selection` acting on single genes, i. e. protein-centered constraints. They show that G + C content, purine / pyrimidine distributions and biological complexity of the organism are the most important factors which determine base compositional rules and genome complexity. Three main facts are here reported: bacteria with high G + C content have more restrictions on base composition than those with low G + C content; at constant G + C content more complex organisms, ranging from prokaryotes to higher eukaryotes (e.g. human) display an increase of repeats 10-20 nucleotides long, which are also partly responsible for long-range correlations; work selection of length 3 to 10 is stronger in human and in bacteria for two distinct reasons. With respect to previous studies, they have also compared the genomic sequence of the archeon Methanococcus jannaschii with those of bacteria and eukaryotes: it shows sometimes an intermediate statistical behaviour.

  3. Searching for genomic constraints

    International Nuclear Information System (INIS)

    Lio', P.; Ruffo, S.

    1998-01-01

    The authors have analyzed general properties of very long DNA sequences belonging to simple and complex organisms, by using different correlation methods. They have distinguished those base compositional rules that concern the entire genome which they call 'genomic constraints' from the rules that depend on the 'external natural selection' acting on single genes, i. e. protein-centered constraints. They show that G + C content, purine / pyrimidine distributions and biological complexity of the organism are the most important factors which determine base compositional rules and genome complexity. Three main facts are here reported: bacteria with high G + C content have more restrictions on base composition than those with low G + C content; at constant G + C content more complex organisms, ranging from prokaryotes to higher eukaryotes (e.g. human) display an increase of repeats 10-20 nucleotides long, which are also partly responsible for long-range correlations; work selection of length 3 to 10 is stronger in human and in bacteria for two distinct reasons. With respect to previous studies, they have also compared the genomic sequence of the archeon Methanococcus jannaschii with those of bacteria and eukaryotes: it shows sometimes an intermediate statistical behaviour

  4. A backtracking evolutionary algorithm for power systems

    Directory of Open Access Journals (Sweden)

    Chiou Ji-Pyng

    2017-01-01

    Full Text Available This paper presents a backtracking variable scaling hybrid differential evolution, called backtracking VSHDE, for solving the optimal network reconfiguration problems for power loss reduction in distribution systems. The concepts of the backtracking, variable scaling factor, migrating, accelerated, and boundary control mechanism are embedded in the original differential evolution (DE to form the backtracking VSHDE. The concepts of the backtracking and boundary control mechanism can increase the population diversity. And, according to the convergence property of the population, the scaling factor is adjusted based on the 1/5 success rule of the evolution strategies (ESs. A larger population size must be used in the evolutionary algorithms (EAs to maintain the population diversity. To overcome this drawback, two operations, acceleration operation and migrating operation, are embedded into the proposed method. The feeder reconfiguration of distribution systems is modelled as an optimization problem which aims at achieving the minimum loss subject to voltage and current constraints. So, the proper system topology that reduces the power loss according to a load pattern is an important issue. Mathematically, the network reconfiguration system is a nonlinear programming problem with integer variables. One three-feeder network reconfiguration system from the literature is researched by the proposed backtracking VSHDE method and simulated annealing (SA. Numerical results show that the perfrmance of the proposed method outperformed the SA method.

  5. Evolutionary Psychology and Intelligence Research

    Science.gov (United States)

    Kanazawa, Satoshi

    2010-01-01

    This article seeks to unify two subfields of psychology that have hitherto stood separately: evolutionary psychology and intelligence research/differential psychology. I suggest that general intelligence may simultaneously be an evolved adaptation and an individual-difference variable. Tooby and Cosmides's (1990a) notion of random quantitative…

  6. Darwinian foundations for evolutionary economics

    NARCIS (Netherlands)

    Stoelhorst, J.W.

    2008-01-01

    This paper engages with the methodological debate on the contribution of Darwinism to Veblen's (1898) evolutionary research program for economics. I argue that ontological continuity, generalized Darwinism, and multi-level selection are necessary building blocks for an explanatory framework that can

  7. Ernst Mayr and Evolutionary Biology

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 10; Issue 7. Polemics and Synthesis: Ernst Mayr and Evolutionary Biology. Renee M Borges. General Article Volume 10 Issue 7 July 2005 pp 21-33. Fulltext. Click here to view fulltext PDF. Permanent link:

  8. Evolutionary Biology Research in India

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 5; Issue 10. Evolutionary Biology Research in India. Information and Announcements Volume 5 Issue 10 October 2000 pp 102-104. Fulltext. Click here to view fulltext PDF. Permanent link: https://www.ias.ac.in/article/fulltext/reso/005/10/0102-0104 ...

  9. Realism, Relativism, and Evolutionary Psychology

    NARCIS (Netherlands)

    Derksen, M.

    Against recent attempts to forge a reconciliation between constructionism and realism, I contend that, in psychology at least, stirring up conflict is a more fruitful strategy. To illustrate this thesis, I confront a school of psychology with strong realist leanings, evolutionary psychology, with

  10. Ancient Biomolecules and Evolutionary Inference

    DEFF Research Database (Denmark)

    Cappellini, Enrico; Prohaska, Ana; Racimo, Fernando

    2018-01-01

    Over the last decade, studies of ancient biomolecules-particularly ancient DNA, proteins, and lipids-have revolutionized our understanding of evolutionary history. Though initially fraught with many challenges, the field now stands on firm foundations. Researchers now successfully retrieve nucleo...

  11. Genetical Genomics for Evolutionary Studies

    NARCIS (Netherlands)

    Prins, J.C.P.; Smant, G.; Jansen, R.C.

    2012-01-01

    Genetical genomics combines acquired high-throughput genomic data with genetic analysis. In this chapter, we discuss the application of genetical genomics for evolutionary studies, where new high-throughput molecular technologies are combined with mapping quantitative trait loci (QTL) on the genome

  12. Evolutionary trends in directional hearing

    DEFF Research Database (Denmark)

    Carr, Catherine E; Christensen-Dalsgaard, Jakob

    2016-01-01

    Tympanic hearing is a true evolutionary novelty that arose in parallel within early tetrapods. We propose that in these tetrapods, selection for sound localization in air acted upon pre-existing directionally sensitive brainstem circuits, similar to those in fishes. Auditory circuits in birds...

  13. Evolutionary dynamics of mammalian karyotypes

    Directory of Open Access Journals (Sweden)

    Carlo Alberto Redi

    2012-12-01

    Full Text Available This special volume of Cytogenetic and Genome Research (edited by Roscoe Stanyon, University of Florence and Alexander Graphodatsky, Siberian division of the Russian Academy of Sciences is dedicated to the fascinating long search of the forces behind the evolutionary dynamics of mammalian karyotypes, revealed after the hypotonic miracle of the 1950s....

  14. Haldane and modern evolutionary genetics

    Indian Academy of Sciences (India)

    Brian Charlesworth

    2017-11-24

    Nov 24, 2017 ... q(t) of an allele at a locus among the gametes produced at time t, to its .... the importance of disease as an evolutionary factor, which is now a ..... VII. Selection intensity as a function of mortality rate. Proc. Camb. Philos. Soc.

  15. Gene Coexpression and Evolutionary Conservation Analysis of the Human Preimplantation Embryos

    Directory of Open Access Journals (Sweden)

    Tiancheng Liu

    2015-01-01

    Full Text Available Evolutionary developmental biology (EVO-DEVO tries to decode evolutionary constraints on the stages of embryonic development. Two models—the “funnel-like” model and the “hourglass” model—have been proposed by investigators to illustrate the fluctuation of selective pressure on these stages. However, selective indices of stages corresponding to mammalian preimplantation embryonic development (PED were undetected in previous studies. Based on single cell RNA sequencing of stages during human PED, we used coexpression method to identify gene modules activated in each of these stages. Through measuring the evolutionary indices of gene modules belonging to each stage, we observed change pattern of selective constraints on PED for the first time. The selective pressure decreases from the zygote stage to the 4-cell stage and increases at the 8-cell stage and then decreases again from 8-cell stage to the late blastocyst stages. Previous EVO-DEVO studies concerning the whole embryo development neglected the fluctuation of selective pressure in these earlier stages, and the fluctuation was potentially correlated with events of earlier stages, such as zygote genome activation (ZGA. Such oscillation in an earlier stage would further affect models of the evolutionary constraints on whole embryo development. Therefore, these earlier stages should be measured intensively in future EVO-DEVO studies.

  16. Five fundamental constraints on theories of the origins of music.

    Science.gov (United States)

    Merker, Bjorn; Morley, Iain; Zuidema, Willem

    2015-03-19

    The diverse forms and functions of human music place obstacles in the way of an evolutionary reconstruction of its origins. In the absence of any obvious homologues of human music among our closest primate relatives, theorizing about its origins, in order to make progress, needs constraints from the nature of music, the capacities it engages, and the contexts in which it occurs. Here we propose and examine five fundamental constraints that bear on theories of how music and some of its features may have originated. First, cultural transmission, bringing the formal powers of cultural as contrasted with Darwinian evolution to bear on its contents. Second, generativity, i.e. the fact that music generates infinite pattern diversity by finite means. Third, vocal production learning, without which there can be no human singing. Fourth, entrainment with perfect synchrony, without which there is neither rhythmic ensemble music nor rhythmic dancing to music. And fifth, the universal propensity of humans to gather occasionally to sing and dance together in a group, which suggests a motivational basis endemic to our biology. We end by considering the evolutionary context within which these constraints had to be met in the genesis of human musicality. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  17. Effect of argon ion sputtering of surface on hydrogen permeation through vanadium

    International Nuclear Information System (INIS)

    Yamawaki, Michio; Namba, Takashi; Yoneoka, Toshiaki; Kanno, Masayoshi; Shida, Koji.

    1983-01-01

    In order to measure the hydrogen permeation rate through V with atomically cleaned surface, an Ar ion sputtering apparatus has been installed in the hydrogen permeability measuring system. The permeation rate of the initial specimen was found to be increased by about one order of magnitude after Ar ion sputtering of its upstream side surface. Repeating of such a sputter-cleaning was not so much effective in increasing the steady state permeation rate as the initial sputtering was, but it accelerated the transient response rate by a factor of 2 or 3. The transient response rate was also accelerated by the increase of hydrogen pressure, but this effect tended to be diminished by the sputter-cleaning of specimen surface. The surface impurity layer on the downstream side of specimen was also inferred to act as a diffusion barrier affecting the steady state permeation rate. The present value of activation energy for hydrogen permeation through V at temperatures below 873K was the smallest one ever obtained, showing that the surface effect was minimized in the present study on account of the surface sputter-cleaning in addition to the ultra high vacuum system. (author)

  18. Liquid crystalline systems for transdermal delivery of celecoxib: in vitro drug release and skin permeation studies.

    Science.gov (United States)

    Estracanholli, Eder André; Praça, Fabíola Silva Garcia; Cintra, Ana Beatriz; Pierre, Maria Bernadete Riemma; Lara, Marilisa Guimarães

    2014-12-01

    Liquid crystalline systems of monoolein/water could be a promising approach for the delivery of celecoxib (CXB) to the skin because these systems can sustain drug release, improve drug penetration into the skin layers and minimize side effects. This study evaluated the potential of these systems for the delivery of CXB into the skin based on in vitro drug release and skin permeation studies. The amount of CXB that permeated into and/or was retained in the skin was assayed using an HPLC method. Polarizing light microscopy studies showed that liquid crystalline systems of monoolein/water were formed in the presence of CXB, without any changes in the mesophases. The liquid crystalline systems decreased drug release when compared to control solution. Drug release was independent of the initial water content of the systems and CXB was released from cubic phase systems, irrespective of the initial water content. The systems released the CXB following zero-order release kinetics. In vitro drug permeation studies showed that cubic phase systems allowed drug permeation and retention in the skin layers. Cubic phase systems of monoolein/water may be promising vehicles for the delivery of CXB in/through the skin because it improved CXB skin permeation compared with the control solution.

  19. Development of permeate flux model for municipal wastewater treatment using membrane bioreactor

    International Nuclear Information System (INIS)

    Geissler, S.; Zhou, H.; Zytner, R.; Melin, T.

    2002-01-01

    In municipal wastewater treatment, membrane filtration technologies receive great attention because they usually produce the better quality effluent, generate less sludge and require a smaller aeration tank volume. However, one main challenge of using membranes is membrane fouling, which results in a permeate flux decrease or transmembrane pressure increase over the time. Many efforts have been directed to develop the mechanistic permeate flux model to correlate the permeate flux with process parameters. However, their applicability has been largely thwarted due to complicated membrane fouling mechanisms and the interactions of many factors affecting the membrane bioreactor. This paper proposes a semi-empirical permeate flux model for the membrane bioreactor (MBR) process using ZENON immersed hollow fibre membrane modules. The semi-empirical model was proposed by assuming that the permeate flux is equal to transmembrane pressure divided by total resistance. The total resistance is divided into two components: an inside membrane resistance and an outer fouling layer resistance. These membrane resistances are then related to the ageing of membrane used. Good correlation was found between the predicted and measured flux, with the mean absolute deviation being less than 4%. The observations also identified some general rules for operating membrane systems. Ideally, it is advisable that high pressure periods be avoided as this leads to a faster increase of non-reversal membrane resistance. It was also observed that membrane preservatives should be washed out carefully prior to use. (author)

  20. Dynamic permeation sources for volatile organic compounds (VOCS): 'a standards test environment' nuclear track detector

    International Nuclear Information System (INIS)

    Hussain, A.; Marr, I.

    2000-01-01

    The generation of a test environment for trace VOCs in urban air or work place has never been easy. This investigation is concerned with the loss rates of VOCs through polythene membrane of different thickness. Permeation glass sample bottles were suspended in the chamber with water jacket at 24 deg. C -+ 0.5 deg. temperature. The condenser was connected with a stream of nitrogen gas at a flow rate of 75-ml min/sup -1 and further diluted with air 500-ml min/sup -1/. The loss in weight of VOCs in each bottle was determined regularly, every 24 hours, with a good agreement. The loss rate depends upon temperature of the bath, thickness of the polythene, internal diameter of the permeation bottle opening. However the loss rate from permeation tubes also depends upon the solubility of the VOCs in the polymer. It is generally believed that the vapors of VOCs in the permeation bottle are dissolved in the polythene sheet (making some sort of solution) and are eventually evaporated out of it. It was observed that the loss rate per minute for benzene > toluene. This simple technique described 'generation of test environment through dynamic permeation source' could be suitable for preparing mixture of benzene, toluene and xylene in atmosphere at ppm levels or lower, with good stability, reliability and also for other compounds of atmospheric interest. (author)

  1. Alfuzosin hydrochloride transdermal films: evaluation of physicochemical, in vitro human cadaver skin permeation and thermodynamic parameters

    Directory of Open Access Journals (Sweden)

    Satyanarayan Pattnaik

    2009-12-01

    Full Text Available Purpose: The main objective of the investigation was to develop a transdermal therapeutic system for alfuzosin hydrochloride and to study the effects of polymeric system and loading dose on the in vitro skin permeation pattern. Materials and methods: Principles of experimental design have been exploited to develop the dosage form. Ratio of ethyl cellulose (EC and polyvinyl pyrrolidone (PVP and loading dose were selected as independent variables and their influence on the cumulative amount of alfuzosin hydrochloride permeated per cm2 of human cadaver skin at 24 h (Q24, permeation flux (J and steady state permeability coefficient (P SS were studied using experimental design. Various physicochemical parameters of the transdermal films were also evaluated. Activation energy for in vitro transdermal permeation has been estimated. Results: Ratio of EC and PVP was found to be the main influential factor for all the dependent variables studied. Drug loading dose was also found to influence the dependent variables but to a lesser extent. Physicochemical parameters of the prepared films were evaluated and found satisfactory. Activation energy for alfuzosin permeation has also been estimated and reported. Conclusion: The therapeutic system was found to be dermatologically non-irritant and hence, a therapeutically effective amount of alfuzosin hydrochloride can be delivered via a transdermal route.

  2. Resistance of gloves and protective clothing materials to permeation of cytostatic solutions.

    Science.gov (United States)

    Krzemińska, Sylwia; Pośniak, Małgorzata; Szewczyńska, Małgorzata

    2018-01-15

    The objective of the work was to determine the resistance of selected protective clothing and glove materials to permeation of cytostatics such as docetaxel, fluorouracil, and doxorubicin. The following glove materials were used: natural rubber latex (code A), acrylonitrile-butadiene rubber (code B) and chloroprene rubber (code C). In addition, we tested a layered material composed of a non-woven polyester (PES), a polypropylene (PP) film, and a non-woven PP used for protective coats (code D). The cytostatics were analyzed by liquid chromatography with diode array detection. The tested samples were placed in a purpose-built permeation cell modified to be different from that specified in the standard EN 6529:2001. The tested materials were characterized by good resistance to solutions containing 2 out of the 3 selected cytostatics: doxorubicin and 5-fluorouracil, as indicated by a breakthrough time of over 480 min. Equally high resistance to permeation of the third cytostatic (docetaxel) was exhibited by natural rubber latex, acrylonitrile-butadiene rubber, and chloroprene rubber. However, docetaxel permeated much more readily through the clothing layered material, compromising its barrier properties. It was found that the presence of additional components in cytostatic preparations accelerated permeation through material samples, thus deteriorating their barrier properties. Int J Occup Med Environ Health 2018;31(3):341-350. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

  3. Chromatic response of polydiacetylene vesicle induced by the permeation of methotrexate.

    Science.gov (United States)

    Shin, Min Jae; Kim, Ye Jin; Kim, Jong-Duk

    2015-07-07

    The noble vesicular system of polydiacetylene showed a red shift using two types of detecting systems. One of the systems involves the absorption of target materials from the outer side of the vesicle, and the other system involves the permeation through the vesicular layers from within the vesicle. The chromatic mixed vesicles of N-(2-aminoethyl)pentacosa-10,12-diynamide (AEPCDA) and dimethyldioctadecylammonium chloride (DODAC) were fabricated by sonication, followed by polymerization by UV irradiation. The stability of monomeric vesicles was observed to increase with the polymerization of the vesicles. Methotrexate was used as a target material. The polymerized mixed vesicles having a blue color were exposed to a concentration gradient of methotrexate, and a red shift was observed indicating the adsorption of methotrexate on the polydiacetylene bilayer. In order to check the chromatic change by the permeation of methotrexate, we separated the vesicle portion, which contained methotrexate inside the vesicle, and checked chromatic change during the permeation of methotrexate through the vesicle. The red shift apparently indicates the disturbance in the bilayer induced by the permeation of methotrexate. The maximum contrast of color appeared at the equal molar ratio of AEPCDA and DODAC, indicating that the formation of flexible and deformable vesicular layers is important for red shift. Therefore, it is hypothesized that the system can be applicable for the chromatic detection of the permeation of methotrexate through the polydiacetylene layer.

  4. Impact of Humidity on In Vitro Human Skin Permeation Experiments for Predicting In Vivo Permeability.

    Science.gov (United States)

    Ishida, Masahiro; Takeuchi, Hiroyuki; Endo, Hiromi; Yamaguchi, Jun-Ichi

    2015-12-01

    In vitro skin permeation studies have been commonly conducted to predict in vivo permeability for the development of transdermal therapeutic systems (TTSs). We clarified the impact of humidity on in vitro human skin permeation of two TTSs having different breathability and then elucidated the predictability of in vivo permeability based on in vitro experimental data. Nicotinell(®) TTS(®) 20 and Frandol(®) tape 40mg were used as model TTSs in this study. The in vitro human skin permeation experiments were conducted under humidity levels similar to those used in clinical trials (approximately 50%) as well as under higher humidity levels (approximately 95%). The skin permeability values of drugs at 95% humidity were higher than those at 50% humidity. The time profiles of the human plasma concentrations after TTS application fitted well with the clinical data when predicted based on the in vitro permeation parameters at 50% humidity. On the other hand, those profiles predicted based on the parameters at 95% humidity were overestimated. The impact of humidity was higher for the more breathable TTS; Frandol(®) tape 40mg. These results show that in vitro human skin permeation experiments should be investigated under realistic clinical humidity levels especially for breathable TTSs. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

  5. Ultrathin graphene-based membrane with precise molecular sieving and ultrafast solvent permeation

    Science.gov (United States)

    Yang, Q.; Su, Y.; Chi, C.; Cherian, C. T.; Huang, K.; Kravets, V. G.; Wang, F. C.; Zhang, J. C.; Pratt, A.; Grigorenko, A. N.; Guinea, F.; Geim, A. K.; Nair, R. R.

    2017-12-01

    Graphene oxide (GO) membranes continue to attract intense interest due to their unique molecular sieving properties combined with fast permeation. However, their use is limited to aqueous solutions because GO membranes appear impermeable to organic solvents, a phenomenon not yet fully understood. Here, we report efficient and fast filtration of organic solutions through GO laminates containing smooth two-dimensional (2D) capillaries made from large (10-20 μm) flakes. Without modification of sieving characteristics, these membranes can be made exceptionally thin, down to ~10 nm, which translates into fast water and organic solvent permeation. We attribute organic solvent permeation and sieving properties to randomly distributed pinholes interconnected by short graphene channels with a width of 1 nm. With increasing membrane thickness, organic solvent permeation rates decay exponentially but water continues to permeate quickly, in agreement with previous reports. The potential of ultrathin GO laminates for organic solvent nanofiltration is demonstrated by showing >99.9% rejection of small molecular weight organic dyes dissolved in methanol. Our work significantly expands possibilities for the use of GO membranes in purification and filtration technologies.

  6. Impacts of chemical enhancers on skin permeation and deposition of terbinafine.

    Science.gov (United States)

    Erdal, Meryem Sedef; Peköz, Ayca Yıldız; Aksu, Buket; Araman, Ahmet

    2014-08-01

    The addition of chemical enhancers into formulations is the most commonly employed approach to overcome the skin barrier. The objective of this work was to evaluate the effect of vehicle and chemical enhancers on the skin permeation and accumulation of terbinafine, an allylamine antifungal drug. Terbinafine (1% w/w) was formulated as a Carbopol 934 P gel formulation in presence and absence of three chemical enhancers, nerolidol, dl-limonene and urea. Terbinafine distribution and deposition in stratum corneum (SC) and skin following 8-h ex vivo permeation study was determined using a sequential tape stripping procedure. The conformational order of SC lipids was investigated by ATR-FTIR spectroscopy. Nerolidol containing gel formulation produced significantly higher enhancement in terbinafine permeation through skin and its skin accumulation was increased. ATR-FTIR results showed enhancer induced lipid bilayer disruption in SC. Urea resulted in enhanced permeation of terbinafine across the skin and a balanced distribution to the SC was achieved. But, dl-limonene could not minimize the accumulation of terbinafine in the upper SC. Nerolidol dramatically improved the skin permeation and deposition of terbinafine in the skin that might help to optimize targeting of the drug to the epidermal sites as required for both of superficial and deep cutaneous fungal infections.

  7. Determination of solvents permeating through chemical protective clothing with a microsensor array.

    Science.gov (United States)

    Park, J; Zellers, E T

    2000-08-01

    The performance of a novel prototype instrument in determining solvents and solvent mixtures permeating through samples of chemical protective clothing (CPC) materials was evaluated. The instrument contains a mini-preconcentrator and an array of three polymer-coated surface-acoustic-wave (SAW) microsensors whose collective response patterns are used to discriminate among multiple permeants. Permeation tests were performed with a 2.54 cm diameter test cell in an open-loop configuration on samples of common glove materials challenged with four individual solvents, three binary mixtures, and two ternary mixtures. Breakthrough times, defined as the times required for the permeation rate to reach a value of 1 microg cm(-2) min(-1), determined by the instrument were within 3 min of those determined in parallel by manual sampling and gas chromatographic analysis. Permeating solvents were recognized (identified) from their response patterns in 59 out of 64 measurements (92%) and their vapor concentrations were quantified to an accuracy of +/- 31% (typically +/- 10%). These results demonstrate the potential for such instrumentation to provide semi-automated field or bench-top screening of CPC permeation resistance.

  8. Skin Delivery of EGCG and Silibinin: Potential of Peptide Dendrimers for Enhanced Skin Permeation and Deposition.

    Science.gov (United States)

    Shetty, Pallavi Krishna; Manikkath, Jyothsna; Tupally, Karnaker; Kokil, Ganesh; Hegde, Aswathi R; Raut, Sushil Y; Parekh, Harendra S; Mutalik, Srinivas

    2017-08-01

    The aim of the present study was to evaluate the ability of the peptide dendrimers to facilitate transdermal delivery of antioxidants, silibinin, and epigallocatechin-3-gallate (EGCG). Drug-peptide dendrimer complexes were prepared and evaluated for their ability to permeate across the skin. The data revealed the ready formation of complexes between drug and peptide dendrimer in a molar ratio of 1:1. In vitro permeation studies using excised rat skin and drug-peptide dendrimer complexes showed highest values for cumulative drug permeation at the end of 12 h (Q 12 ), with corresponding permeability coefficient (Kp) and enhancement ratio values also determined at this time point. With silibinin, 3.96-, 1.81-, and 1.06-fold increase in skin permeation was observed from silibinin-peptide dendrimer complex, simultaneous application of silibinin + peptide dendrimer, and pretreatment of skin with peptide dendrimer, respectively, in comparison with passive diffusion. With EGCG, 9.82-, 2.04-, and 1.72-fold increase in skin permeation was observed from EGCG-peptide dendrimer complex, simultaneous application of EGCG + peptide dendrimer, and pretreatment of skin with peptide dendrimer, respectively, in comparison with passive diffusion. The present study demonstrates the application of peptide dendrimers in effectively delivering antioxidants such as EGCG and silibinin into the skin, thus offering the potential to provide antioxidant effects when delivered via appropriately formulated topical preparations.

  9. Tritium permeation and recovery for the Flibe/He blanket design

    International Nuclear Information System (INIS)

    Moir, R.

    1984-10-01

    This study assumes tritium to be a gas dissolved in molten salt, with TF formation suppressed. Tritium permeates readily through the hot steel tubes of the reactor and steam generator and will leak into the steam system at the rate of about one gram per day in the absence of special permeation barriers, assuming that 1% of the helium coolant flow rate is processed for tritium recovery at 90% efficiency per pass. Tritiated water in the steam system is a personnel hazard at concentration levels well below one part per million and this level would soon be reached without costly isotopic processing. Alternatively, including a combination of permeation barriers on reactor and steam generator tubes and molten salt processing is estimated to reduce the leak rate into the steam system by over two orders of magnitude. For the option with the lowest estimated leak rate, 55 Ci/d, it may be possible to purge the steam system continuously to prevent tritiated water buildup. At best, isotopic separation of dilute tritiated water may not be necessary and for higher leak-rate options the isotopic processing rate can be reduced. The proposed permeation barrier for the reactor tubes is a 10 μm layer of tungsten which, in principle, will reduce tritium blanket permeation by a factor of about 300 below the bare-steel rate

  10. Comparative study of silver nanoparticle permeation using Side-Bi-Side and Franz diffusion cells

    Science.gov (United States)

    Trbojevich, Raul A.; Fernandez, Avelina; Watanabe, Fumiya; Mustafa, Thikra; Bryant, Matthew S.

    2016-03-01

    Better understanding the mechanisms of nanoparticle permeation through membranes and packaging polymers has important implications for the evaluation of drug transdermal uptake, in food safety and the environmental implications of nanotechnology. In this study, permeation of 21 nm diameter silver nanoparticles (AgNPs) was tested using Side-Bi-Side and Franz static diffusion cells through hydrophilic 0.1 and 0.05 µm pore diameter 125 µm thick synthetic cellulose membranes, and 16 and 120 µm thick low-density polyethylene (LDPE) films. Experiments performed with LDPE films discarded permeation of AgNPs or Ag ions over the investigated time-frame in both diffusion systems. But controlled release of AgNPs has been quantified using semipermeable hydrophilic membranes. The permeation followed a quasi-linear time-dependent model during the experimental time-frame, which represents surface reaction-limited permeation. Diffusive flux, diffusion coefficients, and membrane permeability were determined as a function of pore size and diffusion model. Concentration gradient and pore size were key to understand mass transfer phenomena in the diffusion systems.

  11. Comparative study of silver nanoparticle permeation using Side-Bi-Side and Franz diffusion cells

    International Nuclear Information System (INIS)

    Trbojevich, Raul A.; Fernandez, Avelina; Watanabe, Fumiya; Mustafa, Thikra; Bryant, Matthew S.

    2016-01-01

    Better understanding the mechanisms of nanoparticle permeation through membranes and packaging polymers has important implications for the evaluation of drug transdermal uptake, in food safety and the environmental implications of nanotechnology. In this study, permeation of 21 nm diameter silver nanoparticles (AgNPs) was tested using Side-Bi-Side and Franz static diffusion cells through hydrophilic 0.1 and 0.05 µm pore diameter 125 µm thick synthetic cellulose membranes, and 16 and 120 µm thick low-density polyethylene (LDPE) films. Experiments performed with LDPE films discarded permeation of AgNPs or Ag ions over the investigated time-frame in both diffusion systems. But controlled release of AgNPs has been quantified using semipermeable hydrophilic membranes. The permeation followed a quasi-linear time-dependent model during the experimental time-frame, which represents surface reaction-limited permeation. Diffusive flux, diffusion coefficients, and membrane permeability were determined as a function of pore size and diffusion model. Concentration gradient and pore size were key to understand mass transfer phenomena in the diffusion systems.Graphical Abstract

  12. Liposomal buccal mucoadhesive film for improved delivery and permeation of water-soluble vitamins.

    Science.gov (United States)

    Abd El Azim, Heba; Nafee, Noha; Ramadan, Alyaa; Khalafallah, Nawal

    2015-07-05

    This study aims at improving the buccal delivery of vitamin B6 (VB6) as a model highly water-soluble, low permeable vitamin. Two main strategies were combined; first VB6 was entrapped in liposomes, which were then formulated as mucoadhesive film. Both plain and VB6-loaded liposomes (LPs) containing Lipoid S100 and propylene glycol (∼ 200 nm) were then incorporated into mucoadhesive film composed of SCMC and HPMC. Results showed prolonged release of VB6 (72.65%, T50% diss 105 min) after 6h from LP-film compared to control film containing free VB6 (96.37%, T50% diss 30 min). Mucoadhesion was assessed both ex vivo on chicken pouch and in vivo in human. Mucoadhesive force of 0.2N and residence time of 4.4h were recorded. Ex vivo permeation of VB6, across chicken pouch mucosa indicated increased permeation from LP-systems compared to corresponding controls. Interestingly, incorporation of the vesicles in mucoadhesive film reduced the flux by 36.89% relative to LP-dispersion. Meanwhile, both films provided faster initial permeation than the liquid forms. Correlating the cumulative percent permeated ex vivo with the cumulative percent released in vitro indicated that LPs retarded VB6 release but improved permeation. These promising results represent a step forward in the field of buccal delivery of water-soluble vitamins. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Purification Simulation With Vapor Permeation and Distillation-Adsorption In Bioethanol Plant

    Directory of Open Access Journals (Sweden)

    Misri Gozan

    2017-04-01

    Full Text Available High purity of Bioethanol is required in biofuel mixing with gasoline (EXX. In bioethanol production line, the azeotropic property of ethanol-water becomes the barrier for purification process. This study examined two bioethanol separation processes by support of simulation tools, Superpro Designer 9.0 software. Ethanol purity and a low costeconomical process were the major considerations. Purification method of vapor permeation membrane technology was compared with distillation-adsorption method. Data from previous lab experiments and some literatures were used. The results showed that distillation-adsorption method is more economical compared to vapor permeation technology. Payback period of the simulation is 3.9 years and 4.3 years to distillation adsorption and vapor permeation respectively with each IRR value is 20.23% and 17.89%. Initial investment value of vapor permeation is 9.6% higher than distillation method. Significant difference observed in operating costs, since more units involved in vapor permeation require more labors to operate.

  14. Comparative study of silver nanoparticle permeation using Side-Bi-Side and Franz diffusion cells

    Energy Technology Data Exchange (ETDEWEB)

    Trbojevich, Raul A. [U.S. Food and Drug Administration, Division of Biochemical Toxicology, National Center for Toxicological Research (United States); Fernandez, Avelina, E-mail: velifdez@ific.uv.es [Consejo Superior de Investigaciones Científicas-Universitat de València, Parc Científic, Instituto de Física Corpuscular (Spain); Watanabe, Fumiya; Mustafa, Thikra [University Arkansas at Little Rock, Center for Integrative Nanotechnology Sciences (United States); Bryant, Matthew S. [U.S. Food and Drug Administration, Division of Biochemical Toxicology, National Center for Toxicological Research (United States)

    2016-03-15

    Better understanding the mechanisms of nanoparticle permeation through membranes and packaging polymers has important implications for the evaluation of drug transdermal uptake, in food safety and the environmental implications of nanotechnology. In this study, permeation of 21 nm diameter silver nanoparticles (AgNPs) was tested using Side-Bi-Side and Franz static diffusion cells through hydrophilic 0.1 and 0.05 µm pore diameter 125 µm thick synthetic cellulose membranes, and 16 and 120 µm thick low-density polyethylene (LDPE) films. Experiments performed with LDPE films discarded permeation of AgNPs or Ag ions over the investigated time-frame in both diffusion systems. But controlled release of AgNPs has been quantified using semipermeable hydrophilic membranes. The permeation followed a quasi-linear time-dependent model during the experimental time-frame, which represents surface reaction-limited permeation. Diffusive flux, diffusion coefficients, and membrane permeability were determined as a function of pore size and diffusion model. Concentration gradient and pore size were key to understand mass transfer phenomena in the diffusion systems.Graphical Abstract.

  15. Combined use of bile acids and aminoacids to improve permeation properties of acyclovir.

    Science.gov (United States)

    Cirri, M; Maestrelli, F; Mennini, N; Mura, P

    2015-07-25

    The aim of this work was to develop a topical formulation with improved permeation properties of acyclovir. Ursodeoxycholic (UDC) and dehydrocholic (DHC) acids were tested as potential enhancers, alone or in combination with different aminoacids. Equimolar binary and ternary systems of acyclovir with cholic acids and basic, hydrophilic or hydrophobic aminoacids were prepared by co-grinding in a high vibrational micromill. Differential scanning calorimetry (DSC) was used to characterize the solid state of these systems, while their permeation properties were evaluated in vitro through a lipophilic artificial membrane. UDC was more than 2 times more effective than DHC in improving drug AUC and permeation rate. As for the ternary systems drug-UDC-aminoacid, only the combined use of l-lysine with UDC acid produced an evident synergistic effect in enhancing drug permeation properties, enabling an almost 3 and 8 times AUC increase compared to the binary UDC system or the pure drug, respectively. The best systems were selected for the development of topical cream formulations, adequately characterized and tested for in vitro drug permeation properties and stability on storage. The better performance revealed by acyclovir-UDC-l-lysine was mainly attributed to the formation of a more permeable activated system induced by the multicomponent co-grinding process. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Permeation of antigen protein-conjugated nanoparticles and live bacteria through microneedle-treated mouse skin

    Directory of Open Access Journals (Sweden)

    Kumar A

    2011-06-01

    Full Text Available Amit Kumar, Xinran Li, Michael A Sandoval, B Leticia Rodriguez, Brian R Sloat, Zhengrong CuiUniversity of Texas at Austin, College of Pharmacy, Pharmaceutics Division, Austin, TX, USABackground: The present study was designed to evaluate the extent to which pretreatment with microneedles can enhance skin permeation of nanoparticles in vitro and in vivo. Permeation of live bacteria, which are physically nanoparticles or microparticles, through mouse skin pretreated with microneedles was also studied to evaluate the potential risk of microbial infection.Methods and results: It was found that pretreatment of mouse skin with microneedles allowed permeation of solid lipid nanoparticles, size 230 nm, with ovalbumin conjugated on their surface. Transcutaneous immunization in a mouse skin area pretreated with microneedles with ovalbumin nanoparticles induced a stronger antiovalbumin antibody response than using ovalbumin alone. The dose of ovalbumin antigen determined whether microneedle-mediated transcutaneous immunization with ovalbumin nanoparticles induced a stronger immune response than subcutaneous injection of the same ovalbumin nanoparticles. Microneedle treatment permitted skin permeation of live Escherichia coli, but the extent of the permeation was not greater than that enabled by hypodermic injection.Conclusion: Transcutaneous immunization on a microneedle-treated skin area with antigens carried by nanoparticles can potentially induce a strong immune response, and the risk of bacterial infection associated with microneedle treatment is no greater than that with a hypodermic injection.Keywords: antibody responses, safety of microneedles, transepidermal water loss

  17. Permeation of antigen protein-conjugated nanoparticles and live bacteria through microneedle-treated mouse skin

    Science.gov (United States)

    Kumar, Amit; Li, Xinran; Sandoval, Michael A; Rodriguez, B Leticia; Sloat, Brian R; Cui, Zhengrong

    2011-01-01

    Background: The present study was designed to evaluate the extent to which pretreatment with microneedles can enhance skin permeation of nanoparticles in vitro and in vivo. Permeation of live bacteria, which are physically nanoparticles or microparticles, through mouse skin pretreated with microneedles was also studied to evaluate the potential risk of microbial infection. Methods and results: It was found that pretreatment of mouse skin with microneedles allowed permeation of solid lipid nanoparticles, size 230 nm, with ovalbumin conjugated on their surface. Transcutaneous immunization in a mouse skin area pretreated with microneedles with ovalbumin nanoparticles induced a stronger antiovalbumin antibody response than using ovalbumin alone. The dose of ovalbumin antigen determined whether microneedle-mediated transcutaneous immunization with ovalbumin nanoparticles induced a stronger immune response than subcutaneous injection of the same ovalbumin nanoparticles. Microneedle treatment permitted skin permeation of live Escherichia coli, but the extent of the permeation was not greater than that enabled by hypodermic injection. Conclusion: Transcutaneous immunization on a microneedle-treated skin area with antigens carried by nanoparticles can potentially induce a strong immune response, and the risk of bacterial infection associated with microneedle treatment is no greater than that with a hypodermic injection. PMID:21753877

  18. Comparison of implantation-driven permeation characteristics of fusion reactor structural materials

    International Nuclear Information System (INIS)

    Longhurst, G.R.; Anderl, R.A.; Struttmann, D.A.

    1986-01-01

    Implantation-driven permeation experiments have been conducted on samples of the ferritic steel HT-9, the austenitic Primary Candidate Alloy (PCA) and the vanadium alloy V-15Cr-5Ti using D 3 + ions under conditions that simulate charge-exchange neutral loading on a fusion reactor first wall. The steels all exhibited an initially intense permeation ''spike'' followed by an exponential decrease to low steady-state values. That spike was not evident in the V-15Cr-5Ti experiments. Steady-state permeation was highest in the vanadium alloy and lowest in the austenitic steel. Though permeation rates in the HT-9 were lower than those in V-15Cr-5Ti, permeation transients were much faster in HT-9 than in other materials tested. Ion-beam sputtering of the surface in the steel experiments resulted in enhanced remission at the front surface, whereas in the vanadium tests, recombination and diffusivity both appeared to diminish as the deuterium concentration rose. This may be due to a phase change in the material. We conclude that for conditions comparable to those of these experiments, tritium retention and loss in first wall structures made of steels will be less than in structures made of V-15Cr-5Ti

  19. Implications of recent implantation-driven permeation experiments for fusion reactor safety

    International Nuclear Information System (INIS)

    Longhurst, G.R.; Anderl, R.A.; Struttmann, D.A.

    1986-01-01

    Metal structures exposed to the plasma in tritium-burning fusion reactors will be subject to implantation-driven permeation (IDP) of tritium. Permeation rates for IDP in fusion structural materials are usually high because the tritium atoms enter the material without having to go through the dissociation and solution steps required of tritium-bearing gas molecules. These surface processes, which may be rate limiting in PDP, actually enhance permeation in IDP by inhibiting the return of tritium to the plasma side of the structure. Experiments have been conducted at the Idaho National Engineering Laboratory (INEL) to investigate the nature of IDP by simulating conditions experienced by structures exposed to the plasma. These experiments have shown that surface conditions are important to tritium permeation in materials endothermic to hydrogen solution such as austenitic and ferritic steels. In reactive metals such as vanadium, surface processes appear to totally control the permeation. The purpose of this paper is to review the progress of those experiments and to discuss the implications that the results have regarding the tritium-related safety concerns of fusion reactors

  20. Influence of nitrogen ion implantation on hydrogen permeation in an extra mild steel

    International Nuclear Information System (INIS)

    Brass, A.M.; Chene, J.; Pivin, J.C.

    1989-01-01

    This paper presents the first results on the effect of nitrogen implantation on hydrogen permeation in steels. Nitrogen can modify superficially the steel's chemistry and/or microstructure depending on the fluence and thereby affect the processes of hydrogen diffusion and trapping. The implantations were performed on low carbon steel specimens with different nominal doses (1% to 10% and 33% nitrogen in a superficial layer of approximately 100 to 120 nm). The corresponding microstructures were characterized and permeation tests were conducted at room temperature in a double electrolytic cell. The nitrogen implanted layers on iron affects the electrochemical behaviour of the surface and the permeation in the material. This effect depends on the nitrogen concentration in the layer and on the corresponding microstructure. A continuous Fe 2 N layer acts as an efficient barrier to hydrogen entry and permeation when the layer is located on the entry face of the permeation membrane. This effect is stronger when the implanted layer is on the downstream face of the membrane. The low permeability values are mainly attributed to a lower hydrogen solubility in the implanted layer, whereas hydrogen trapping on defects and nitride precipitates delay hydrogen penetration. (author)

  1. Wavelet evolutionary network for complex-constrained portfolio rebalancing

    Science.gov (United States)

    Suganya, N. C.; Vijayalakshmi Pai, G. A.

    2012-07-01

    Portfolio rebalancing problem deals with resetting the proportion of different assets in a portfolio with respect to changing market conditions. The constraints included in the portfolio rebalancing problem are basic, cardinality, bounding, class and proportional transaction cost. In this study, a new heuristic algorithm named wavelet evolutionary network (WEN) is proposed for the solution of complex-constrained portfolio rebalancing problem. Initially, the empirical covariance matrix, one of the key inputs to the problem, is estimated using the wavelet shrinkage denoising technique to obtain better optimal portfolios. Secondly, the complex cardinality constraint is eliminated using k-means cluster analysis. Finally, WEN strategy with logical procedures is employed to find the initial proportion of investment in portfolio of assets and also rebalance them after certain period. Experimental studies of WEN are undertaken on Bombay Stock Exchange, India (BSE200 index, period: July 2001-July 2006) and Tokyo Stock Exchange, Japan (Nikkei225 index, period: March 2002-March 2007) data sets. The result obtained using WEN is compared with the only existing counterpart named Hopfield evolutionary network (HEN) strategy and also verifies that WEN performs better than HEN. In addition, different performance metrics and data envelopment analysis are carried out to prove the robustness and efficiency of WEN over HEN strategy.

  2. Supergravity constraints on monojets

    International Nuclear Information System (INIS)

    Nandi, S.

    1986-01-01

    In the standard model, supplemented by N = 1 minimal supergravity, all the supersymmetric particle masses can be expressed in terms of a few unknown parameters. The resulting mass relations, and the laboratory and the cosmological bounds on these superpartner masses are used to put constraints on the supersymmetric origin of the CERN monojets. The latest MAC data at PEP excludes the scalar quarks, of masses up to 45 GeV, as the origin of these monojets. The cosmological bounds, for a stable photino, excludes the mass range necessary for the light gluino-heavy squark production interpretation. These difficulties can be avoided by going beyond the minimal supergravity theory. Irrespective of the monojets, the importance of the stable γ as the source of the cosmological dark matter is emphasized

  3. Temporal Concurrent Constraint Programming

    DEFF Research Database (Denmark)

    Valencia, Frank Dan

    Concurrent constraint programming (ccp) is a formalism for concurrency in which agents interact with one another by telling (adding) and asking (reading) information in a shared medium. Temporal ccp extends ccp by allowing agents to be constrained by time conditions. This dissertation studies...... temporal ccp by developing a process calculus called ntcc. The ntcc calculus generalizes the tcc model, the latter being a temporal ccp model for deterministic and synchronouss timed reactive systems. The calculus is built upon few basic ideas but it captures several aspects of timed systems. As tcc, ntcc...... structures, robotic devises, multi-agent systems and music applications. The calculus is provided with a denotational semantics that captures the reactive computations of processes in the presence of arbitrary environments. The denotation is proven to be fully-abstract for a substantial fragment...

  4. Towards a mechanistic foundation of evolutionary theory.

    Science.gov (United States)

    Doebeli, Michael; Ispolatov, Yaroslav; Simon, Burt

    2017-02-15

    Most evolutionary thinking is based on the notion of fitness and related ideas such as fitness landscapes and evolutionary optima. Nevertheless, it is often unclear what fitness actually is, and its meaning often depends on the context. Here we argue that fitness should not be a basal ingredient in verbal or mathematical descriptions of evolution. Instead, we propose that evolutionary birth-death processes, in which individuals give birth and die at ever-changing rates, should be the basis of evolutionary theory, because such processes capture the fundamental events that generate evolutionary dynamics. In evolutionary birth-death processes, fitness is at best a derived quantity, and owing to the potential complexity of such processes, there is no guarantee that there is a simple scalar, such as fitness, that would describe long-term evolutionary outcomes. We discuss how evolutionary birth-death processes can provide useful perspectives on a number of central issues in evolution.

  5. Applied evolutionary economics and economic geography

    NARCIS (Netherlands)

    Frenken, K.

    2007-01-01

    Applied Evolutionary Economics and Economic Geography" aims to further advance empirical methodologies in evolutionary economics, with a special emphasis on geography and firm location. It does so by bringing together a select group of leading scholars including economists, geographers and

  6. Evolutionary biology of bacterial and fungal pathogens

    National Research Council Canada - National Science Library

    Baquero, F

    2008-01-01

    ... and Evolutionary Dynamics of Pathogens * 21 Keith A. Crandall and Marcos Pérez-Losada II. Evolutionary Genetics of Microbial Pathogens 4. Environmental and Social Influences on Infectious Disea...

  7. Biophysics of protein evolution and evolutionary protein biophysics

    Science.gov (United States)

    Sikosek, Tobias; Chan, Hue Sun

    2014-01-01

    The study of molecular evolution at the level of protein-coding genes often entails comparing large datasets of sequences to infer their evolutionary relationships. Despite the importance of a protein's structure and conformational dynamics to its function and thus its fitness, common phylogenetic methods embody minimal biophysical knowledge of proteins. To underscore the biophysical constraints on natural selection, we survey effects of protein mutations, highlighting the physical basis for marginal stability of natural globular proteins and how requirement for kinetic stability and avoidance of misfolding and misinteractions might have affected protein evolution. The biophysical underpinnings of these effects have been addressed by models with an explicit coarse-grained spatial representation of the polypeptide chain. Sequence–structure mappings based on such models are powerful conceptual tools that rationalize mutational robustness, evolvability, epistasis, promiscuous function performed by ‘hidden’ conformational states, resolution of adaptive conflicts and conformational switches in the evolution from one protein fold to another. Recently, protein biophysics has been applied to derive more accurate evolutionary accounts of sequence data. Methods have also been developed to exploit sequence-based evolutionary information to predict biophysical behaviours of proteins. The success of these approaches demonstrates a deep synergy between the fields of protein biophysics and protein evolution. PMID:25165599

  8. The non-random clustering of non-synonymous substitutions and its relationship to evolutionary rate

    Directory of Open Access Journals (Sweden)

    Stone Eric A

    2011-08-01

    Full Text Available Abstract Background Protein sequences are subject to a mosaic of constraint. Changes to functional domains and buried residues, for example, are more apt to disrupt protein structure and function than are changes to residues participating in loops or exposed to solvent. Regions of constraint on the tertiary structure of a protein often result in loose segmentation of its primary structure into stretches of slowly- and rapidly-evolving amino acids. This clustering can be exploited, and existing methods have done so by relying on local sequence conservation as a signature of selection to help identify functionally important regions within proteins. We invert this paradigm by leveraging the regional nature of protein structure and function to both illuminate and make use of genome-wide patterns of local sequence conservation. Results Our hypothesis is that the regional nature of structural and functional constraints will assert a positive autocorrelation on the evolutionary rates of neighboring sites, which, in a pairwise comparison of orthologous proteins, will manifest itself as the clustering of non-synonymous changes across the amino acid sequence. We introduce a dispersion ratio statistic to test this and related hypotheses. Using genome-wide interspecific comparisons of orthologous protein pairs, we reveal a strong log-linear relationship between the degree of clustering and the intensity of constraint. We further demonstrate how this relationship varies with the evolutionary distance between the species being compared. We provide some evidence that proteins with a history of positive selection deviate from genome-wide trends. Conclusions We find a significant association between the evolutionary rate of a protein and the degree to which non-synonymous changes cluster along its primary sequence. We show that clustering is a non-redundant predictor of evolutionary rate, and we speculate that conflicting signals of clustering and constraint may

  9. RF plasma-driven hydrogen permeation through a biased iron membrane

    International Nuclear Information System (INIS)

    Banno, T.; Waelbroeck, F.; Winter, J.

    1984-01-01

    The steady-state RF plasma-driven hydrogen permeation through an electrically biased iron membrane has been investigated as a function of the bias potential Vsub(M) for membrane temperatures in the range of 150-400 0 C. Vsub(M) has been gradually increased positively from the floating potential of the membrane. The permeation flux decreases when Vsub(M) increases at low voltages: positive hydrogen ions are repelled. The membrane temperature does not influence this effect measurably. The permeation flux starts to increase when Vsub(M) is raised higher, i.e. when energetic electrons strike the surface. This phenomenon shows a pronounced temperature dependence - the enhancement is largest for the lowest temperatures. The effect is interpreted in terms of an electron-induced dissociation of hydrogen molecules on the membrane surface. (orig.)

  10. Characterization and utilization of the permeate and retentate obtained after “dead-end” ultrafiltration

    Directory of Open Access Journals (Sweden)

    Vasić Vesna M.

    2013-01-01

    Full Text Available In the recent years, with the increase in bioethanol production, the increasing amounts of distillery wastewater are generated. Such wastewater (stillage is one of the most polluted waste product of the food and beverage industries. The present study evaluates the treatment of distillery wastewater by ultrafiltration (UF, in order to reduce its pollution and evaluate the composition of the permeate and retentate. Polyethersulfone ultrafiltration membrane with molecular weight cut-off (MWCO 30000 Da, was used for the experiments. The UF was carried out in dead-end mode. The results of the analyses of the permeate and retentate obtained after ultrafiltration were considered as well as different ways for their further utilization. The pollutant level in the permeate was decreased significantly in comparison to the raw stillage, and suspended solids were completely removed from the stillage. [Projekat Ministarstva nauke Republike Srbije, br. TR 31002

  11. Testing of Disposable Protective Garments Against Isocyanate Permeation From Spray Polyurethane Foam Insulation.

    Science.gov (United States)

    Mellette, Michael P; Bello, Dhimiter; Xue, Yalong; Yost, Michael; Bello, Anila; Woskie, Susan

    2018-05-12

    Diisocyanates (isocyanates), including methylene diphenyl diisocyanate (MDI), are the primary reactive components of spray polyurethane foam (SPF) insulation. They are potent immune sensitizers and a leading cause of occupational asthma. Skin exposure to isocyanates may lead to both irritant and allergic contact dermatitis and possibly contribute to systemic sensitization. More than sufficient evidence exists to justify the use of protective garments to minimize skin contact with aerosolized and raw isocyanate containing materials during SPF applications. Studies evaluating the permeation of protective garments following exposure to SPF insulation do not currently exist. To conduct permeation testing under controlled conditions to assess the effectiveness of common protective gloves and coveralls during SPF applications using realistic SPF product formulations. Five common disposable garment materials [disposable latex gloves (0.07 mm thickness), nitrile gloves (0.07 mm), vinyl gloves (0.07 mm), polypropylene coveralls (0.13 mm) and Tyvek coveralls (0.13 mm)] were selected for testing. These materials were cut into small pieces and assembled into a permeation test cell system and coated with a two-part slow-rise spray polyurethane foam insulation. Glass fiber filters (GFF) pretreated with 1-(9-anthracenylmethyl)piperazine) (MAP) were used underneath the garment to collect permeating isocyanates. GFF filters were collected at predetermined test intervals between 0.75 and 20.00 min and subsequently analyzed using liquid chromatography-tandem mass spectrometry. For each garment material, we assessed (i) the cumulative concentration of total isocyanate, including phenyl isocyanate and three MDI isomers, that effectively permeated the material over the test time; (ii) estimated breakthrough detection time, average permeation rate, and standardized breakthrough time; from which (iii) recommendations were developed for the use of similar protective garments following

  12. Investigating the sonophoresis effect on the permeation of diclofenac sodium using 3D skin equivalent.

    Science.gov (United States)

    Aldwaikat, Mai; Alarjah, Mohammed

    2015-01-01

    Ultrasound temporally increases skin permeability by altering stratum corneum SC function (sonophoresis). The objective of this study was to evaluate the effect of variable ultrasound conditions on the permeation of diclofenac sodium DS with range of physicochemical properties through EpiDerm™. Permeation studies were carried out in vitro using Franz diffusion cell. HPLC method was used for the determination of the concentration of diclofenac sodium in receiving compartment. Parameters like ultrasound frequency, application time, amplitude, and mode of sonication and distance of ultrasound horn from skin were investigated, and the conditions where the maximum enhancement rate obtained were determined. Application of ultrasound enhanced permeation of diclofenac sodium across EpiDerm™ by fivefolds. The most effective enhancing parameters were power sonication of 20kHz frequency, 20% amplitude at continuous mode for 5min. Copyright © 2014. Published by Elsevier B.V.

  13. Effect of phonophoresis on skin permeation of commercial anti-inflammatory gels: sodium diclofenac and ketoprofen.

    Science.gov (United States)

    Souza, Jaqueline; Meira, Alianise; Volpato, Nadia Maria; Mayorga, Paulo; Gottfried, Carmem

    2013-09-01

    This study evaluated the use of ultrasound in combination with the commercial anti-inflammatory drugs ketoprofen and sodium diclofenac, according to the parameters used in physiotherapy. Ketoprofen and sodium diclofenac were used in the Franz diffusion cell model adapted to an ultrasound transducer in three conditions: no ultrasound, one application of ultrasound and two applications of ultrasound. High-performance liquid chromatography was used to quantify the total amount of drug permeating skin per unit area, as well as flux and latency. The results showed that for ketoprofen, the amount of drug permeating skin and flux increased with two ultrasound applications. Permeation of sodium diclofenac decreased in the presence of ultrasound. Ultrasound parameters and drug properties must be considered in the use of phonophoresis. Copyright © 2013 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  14. Experimental measurements of the permeation of hydrogen isotopes in lithium filled niobium cells

    International Nuclear Information System (INIS)

    Goodall, D.H.J.; McCracken, G.M.; Austin, G.E.

    1976-01-01

    Lithium filled niobium cells have been heated in vacua at temperatures in the range 300 to 900 0 C. By measuring the flow of deuterium into the cell it has been possible to make estimates of the rate of permeation of deuterium in the niobium wall. After initial fast diffusion into the capsule the rate of permeation becomes very much slower than that determined by diffusion in the bulk niobium indicating that a second, slower, rate process is involved. Measurements of the rate of deuterium permeation out of the cell have been made for a number of different cell geometries and a range of temperatures. The results indicate that the slow rate process, which is dominant at low concentrations, is the desorption step from the metal to the gas phase

  15. Peculiarities of hydrogen permeation through Zr–1%Nb alloy and evaluation of terminal solid solubility

    Energy Technology Data Exchange (ETDEWEB)

    Denisov, E.A.; Kompaniets, M.V.; Kompaniets, T.N., E-mail: tkompaniets@spbu.ru; Bobkova, I.S.

    2016-04-15

    Hydrogen permeation through Zr–1%Nb alloy was studied at the temperature below the temperature of α-β transition. Analysis of the transient permeation curves from a closed volume in a surface limited regime allowed to determine total and mobile hydrogen concentrations. At the mobile hydrogen concentration of 4.3 at% a part of the absorbed hydrogen is cut out of permeation process. Increase of the mobile hydrogen concentration in α-phase of Zr–1%Nb alloy is ceasing at the concentration of (5.5 ± 0.3) at%, which is the maximum possible concentration of the mobile hydrogen in α-phase of the studied alloy. From this moment on all absorbed hydrogen is spent on hydride formation. The obtained results are compared with those obtained by means of traditional techniques for terminal solid solubility determination.

  16. The influence of corneocyte structure on the interpretation of permeation profiles of nanoparticles across skin

    Energy Technology Data Exchange (ETDEWEB)

    Pinheiro, T. [LFI, Instituto Tecnologico Nuclear, and Centro de Fisica Nuclear, Universidade Lisboa E.N. 10, 2685-953 Sacavem (Portugal)]. E-mail: murmur@itn.pt; Pallon, J. [Lund Institute of Technology, Physics Department, Lund University, Lund (Sweden)]. E-mail: Jan.Pallon@pixe.lth.se; Alves, L.C. [LFI, Instituto Tecnologico Nuclear, and Centro de Fisica Nuclear, Universidade Lisboa E.N. 10, 2685-953 Sacavem (Portugal)]. E-mail: lcalves@itn.pt; Verissimo, A. [LFI, Instituto Tecnologico Nuclear, and Centro de Fisica Nuclear, Universidade Lisboa E.N. 10, 2685-953 Sacavem (Portugal)]. E-mail: averissimo@vims.edu; Filipe, P. [Departamento Dermatologia, Hospital Sta. Maria, Lisbon (Portugal)]. E-mail: pfilipe@fm.ul.pt; Silva, J.N. [Departamento Dermatologia, Hospital Sta. Maria, Lisbon (Portugal)]. E-mail: maiasilva@fm.ul.pt; Silva, R. [Departamento Dermatologia, Hospital Sta. Maria, Lisbon (Portugal)]. E-mail: rpalminhas@netcabo.pt

    2007-07-15

    The permeability of skin to nanoparticles of titanium dioxide (TiO{sub 2}) used in sunscreens as a reflector of the UV wavelengths of sunlight, was examined using nuclear microscopy techniques. Special attention was given to the permeation characteristics of these nanoparticles across the outer layers of skin, the stratum corneum, in healthy and psoriatic skin condition. Aspects that may influence the interpretation of results such as sample preparation difficulties and skin condition were focused. Sample preparation can damage the integrity of the corneocyte layers inducing unwanted artefacts that may bias the evaluation of results. Irradiation conditions may also introduce distortions in the labile structures of human skin. Skin condition, such as loss of corneocyte cohesion occurring in psoriasis also influence the permeation profile of the nanoparticles. Weighing and accounting for these features in the examination of skin by nuclear microscopy is crucial to accurately assess the TiO{sub 2} nanoparticles permeation depth.

  17. In vitro permeation studies of nanoemulsions containing ketoprofen as a model drug.

    Science.gov (United States)

    Kim, Beom Su; Won, Myoung; Lee, Kang Min; Kim, Cheo Sang

    2008-09-01

    We prepared a nanoemulsion system with benzyl alcohol/ ethanol/Solutol/smash(R) HS 15 /water. Ketoprofen was used as a model drug in this study. The nanoemulsions of this system evidenced a high degree of stability. The droplet diameter did not change over a period of at least 3 months. The nanoemulsion containing 4% benzyl alcohol evidenced a permeation rate higher than was observed with the 1% and 2% nanoemulsions. Also the nanoemulsion containing 1% Solutol(R) HS 15 provided a permeation rate higher than was seen with the 2% and 4% nanoemulsions. All ketoprofen-loaded nanoemulsions enhanced the in vitro permeation rate through mouse skins as compared to the control.

  18. Effects of thin films on inventory, permeation and re-emission of energetic hydrogen

    International Nuclear Information System (INIS)

    Ohyabu, N.; Nakamura, Y.; Nakahara, Y.; Livshits, A.; Alimov, V.; Busnyuk, A.; Notkin, M.; Samartsev, A.; Doroshin, A.

    2000-01-01

    A non-metallic coating thicker than the implantation depth may protect a metal against tritium retention and permeation. However, a thinner film has quite the opposite effect: a dramatic increase of permeation and retention, and a corresponding suppression of re-emission. In view of the benefits expected from particle control with a superpermeable membrane placed right inside the divertor, the behavior of a Nb sample was investigated in a plasma-membrane device having a graphite target. Even polyatomic carbide coating was found not to hinder hydrogen absorption and permeation. Polyatomic non-carbide C films effectively inhibits it, but the formation of such films depends on H and C fluxes, H energy and metal temperature. A durable isolation of suprathermal hydrogen with the superpermeable membrane was observed at a high enough ratio between H and C fluxes, and the effects of carbon were found to have a non-monotonic temperature dependence

  19. Deuterium gas-driven permeation and subsequent retention in rolled tungsten foils

    International Nuclear Information System (INIS)

    Liu, Feng; Zhou, Haishan; Li, Xiao-Chun; Xu, Yuping; An, Zhongqing; Mao, Hongmin; Xing, Wenjing; Hou, Qing; Luo, Guang-Nan

    2014-01-01

    Experiments concerning deuterium gas-driven permeation through rolled tungsten foils in the temperature range of 850–950 K and subsequent deuterium retention have been performed. The steady state permeation flux of deuterium is proportional to the square root of the driving pressure. The permeability of deuterium is in an order of 10 −14 mol m −1 s −1 Pa −1/2 in this temperature range and the activation energy for permeation is 1.21 eV. Measurements of diffusivity are significantly affected by the driving pressure, which can be well explained by a saturable-trap model. Thermal desorption spectra of samples feature a single deuterium release peak at about 873 K. TMAP 4 modeling of this peak gives a detrapping energy of 1.70 eV, which fits the dissociation enthalpy of deuterium desorbing from the inner wall of vacancy clusters or pores in tungsten

  20. Deuterium gas-driven permeation and subsequent retention in rolled tungsten foils

    Science.gov (United States)

    Liu, Feng; Zhou, Haishan; Li, Xiao-Chun; Xu, Yuping; An, Zhongqing; Mao, Hongmin; Xing, Wenjing; Hou, Qing; Luo, Guang-Nan

    2014-12-01

    Experiments concerning deuterium gas-driven permeation through rolled tungsten foils in the temperature range of 850-950 K and subsequent deuterium retention have been performed. The steady state permeation flux of deuterium is proportional to the square root of the driving pressure. The permeability of deuterium is in an order of 10-14 mol m-1 s-1 Pa-1/2 in this temperature range and the activation energy for permeation is 1.21 eV. Measurements of diffusivity are significantly affected by the driving pressure, which can be well explained by a saturable-trap model. Thermal desorption spectra of samples feature a single deuterium release peak at about 873 K. TMAP 4 modeling of this peak gives a detrapping energy of 1.70 eV, which fits the dissociation enthalpy of deuterium desorbing from the inner wall of vacancy clusters or pores in tungsten.

  1. Production of citric acid from whey permeate by fermentation using Aspergillus niger

    Energy Technology Data Exchange (ETDEWEB)

    Hossain, M; Brooks, J D

    1983-08-01

    The use of lactic casein whey permeate as a substrate for citric acid production by fermentation has been investigated. Using a mutant strain of Aspergillus niger IMI 41874 in fermenter culture, a citric acid concentration of 8.3 g/l, representing a yield of 19% (w/w) based on lactose utilized, has been observed. Supplementation of the permeate with lactose (final concentration 140 g/l) increased the production to 14.8 g/l (yield 23%). The natural pH of the permeate (pH 4.5) was the most suitable initial pH for the process, and pH control during the fermentation was unnecessary. The addition of methanol (final concentration 3% v/v) to the fermentation increased the citric acid production to 25 g/l (yield 33%, based on lactose utilized). 13 references.

  2. Preparation and Skin Permeation Study of N, N- Diethyl- meta-Toluamide Semi Solid Formulations

    Directory of Open Access Journals (Sweden)

    Solmaz Ghaffari

    2013-06-01

    Full Text Available N,N-Diethyl meta Toluamide (DEET is an insect repellent agent that contrary to its benefits, if is used in formulations with high skin permeation, will produce side effects of different severity. This study attempted to achieve a semi-solid DEET containing formulation with good appearance, sufficient spreadity, suitable viscosity for tube and jar filling, compatible pH with skin, reasonable stability, longer release time, and the less skin permeation. To obtain such a formulation, three types of DEET containing semi solids including gels (hydrophile, creams (emulsion and ointments (lipophile, and their characteristics were compared with each other and with Off! Brand. Results showed that one of the prepared creams with the proper viscosity, stability, appearance and spreadity, had the least drug release in six hours and less skin permeation of DEET as compared with Off!. Hence the preparation was introduced as the optimal formulation.

  3. Investigation of non-magnetic alloys for the suppression of tritium permeation. Final report

    International Nuclear Information System (INIS)

    1980-07-01

    This report describes a small (300 man hour) literature survey relating to the suppression of tritium loss by permeation through the walls of fusion reactors. The program was based on prior in-house Thermacore work to suppress hydrogen permeation into high temperature (800 0 C) heat pipes. The Thermacore approach involves selection of a steel with a small (.5 to 5%) aluminum content. The aluminum is diffused to the surface and oxidized. The present work was aimed at identification of alloys which might combine low tritium permeation with other properties desired in fusion reactor vessels, heat exchangers, lithium-handling plumbing and other components likely to contain tritium. These properties include low radiation damage, low magnetic permeability, high temperature strength, and compatibility with potential heat transfer and blanket materials. The work consisted of two tasks: Problem Definition and Literature Search and Analysis

  4. The citation field of evolutionary economics

    NARCIS (Netherlands)

    Dolfsma, Wilfred; Leydesdorff, Loet

    2010-01-01

    Evolutionary economics has developed into an academic field of its own, institutionalized around, amongst others, the Journal of Evolutionary Economics (JEE). This paper analyzes the way and extent to which evolutionary economics has become an interdisciplinary journal, as its aim was: a journal

  5. Essays on nonlinear evolutionary game dynamics

    NARCIS (Netherlands)

    Ochea, M.I.

    2010-01-01

    Evolutionary game theory has been viewed as an evolutionary repair of rational actor game theory in the hope that a population of boundedly rational players may attain convergence to classic rational solutions, such as the Nash Equilibrium, via some learning or evolutionary process. In this thesis

  6. Minimal Flavor Constraints for Technicolor

    DEFF Research Database (Denmark)

    Sakuma, Hidenori; Sannino, Francesco

    2010-01-01

    We analyze the constraints on the the vacuum polarization of the standard model gauge bosons from a minimal set of flavor observables valid for a general class of models of dynamical electroweak symmetry breaking. We will show that the constraints have a strong impact on the self-coupling and mas......We analyze the constraints on the the vacuum polarization of the standard model gauge bosons from a minimal set of flavor observables valid for a general class of models of dynamical electroweak symmetry breaking. We will show that the constraints have a strong impact on the self...

  7. Social Constraints on Animate Vision

    National Research Council Canada - National Science Library

    Breazeal, Cynthia; Edsinger, Aaron; Fitzpatrick, Paul; Scassellati, Brian

    2000-01-01

    .... In humanoid robotic systems, or in any animate vision system that interacts with people, social dynamics provide additional levels of constraint and provide additional opportunities for processing economy...

  8. Exploring the miRNA regulatory network using evolutionary correlations.

    Directory of Open Access Journals (Sweden)

    Benedikt Obermayer

    2014-10-01

    Full Text Available Post-transcriptional regulation by miRNAs is a widespread and highly conserved phenomenon in metazoans, with several hundreds to thousands of conserved binding sites for each miRNA, and up to two thirds of all genes under miRNA regulation. At the same time, the effect of miRNA regulation on mRNA and protein levels is usually quite modest and associated phenotypes are often weak or subtle. This has given rise to the notion that the highly interconnected miRNA regulatory network exerts its function less through any individual link and more via collective effects that lead to a functional interdependence of network links. We present a Bayesian framework to quantify conservation of miRNA target sites using vertebrate whole-genome alignments. The increased statistical power of our phylogenetic model allows detection of evolutionary correlation in the conservation patterns of site pairs. Such correlations could result from collective functions in the regulatory network. For instance, co-conservation of target site pairs supports a selective benefit of combinatorial regulation by multiple miRNAs. We find that some miRNA families are under pronounced co-targeting constraints, indicating a high connectivity in the regulatory network, while others appear to function in a more isolated way. By analyzing coordinated targeting of different curated gene sets, we observe distinct evolutionary signatures for protein complexes and signaling pathways that could reflect differences in control strategies. Our method is easily scalable to analyze upcoming larger data sets, and readily adaptable to detect high-level selective constraints between other genomic loci. We thus provide a proof-of-principle method to understand regulatory networks from an evolutionary perspective.

  9. Re-evaluation of SiC permeation coefficients at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Yasushi, E-mail: yama3707@kansai-u.ac.jp [Faculty of Engineering Science, Kansai Univ., Yamate-cho, Suita, Osaka 564-8680 (Japan); Murakami, Yuichiro; Yamaguchi, Hirosato; Yamamoto, Takehiro; Yonetsu, Daigo [Faculty of Engineering Science, Kansai Univ., Yamate-cho, Suita, Osaka 564-8680 (Japan); Noborio, Kazuyuki [Hydrogen Isotope Research Center, Univ. of Toyama, Toyama, Toyama 930-8555 (Japan); Konishi, Satoshi [Institute of Advanced Energy, Kyoto Univ., Gokasho, Uji, Kyoto 611-0011 (Japan)

    2016-11-01

    Highlights: • The deuterium permeation coefficients of CVD-SiC at 600–950 °C were evaluated. • The wraparound flow was reduced to less than 1/100th of the permeation flow. • CVD-SiC materials are very effective as hydrogen isotope permeation barriers. - Abstract: Since 2007, our group has studied the deuterium permeation and diffusion coefficients for SiC materials at temperatures above 600 °C as a means of evaluating the tritium inventory and permeation in fusion blankets. During such measurements, control and evaluation of the wraparound flow through the sample holder are important, and so the heated sample holder is enclosed by a glass tube and kept under vacuum during experimental trials. However, detailed studies regarding the required degree of vacuum based on model calculations have shown that the wraparound flow is much larger than expected, and so can affect measurements at high temperatures. We therefore modified the measurement apparatus based on calculations involving reduced pressure in the glass tube, and are now confident that the measurement error is only several percent, even at 950 °C. In this paper, recent experimental results obtained with a chemical vapor deposition (CVD)-SiC sample over the temperature range of 600–950 °C are presented, showing that the permeation coefficient for CVD-SiC is more than three orders of magnitude smaller than that for stainless steel (SS316) at 600 °C, and that at 950 °C, the coefficient for CVD-SiC is almost equal to that for SUS316 at 550 °C.

  10. Modifier constraint in alkali borophosphate glasses using topological constraint theory

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiang [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Zeng, Huidan, E-mail: hdzeng@ecust.edu.cn [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Jiang, Qi [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Zhao, Donghui [Unifrax Corporation, Niagara Falls, NY 14305 (United States); Chen, Guorong [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Wang, Zhaofeng; Sun, Luyi [Department of Chemical & Biomolecular Engineering and Polymer Program, Institute of Materials Science, University of Connecticut, Storrs, CT 06269 (United States); Chen, Jianding [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China)

    2016-12-01

    In recent years, composition-dependent properties of glasses have been successfully predicted using the topological constraint theory. The constraints of the glass network are derived from two main parts: network formers and network modifiers. The constraints of the network formers can be calculated on the basis of the topological structure of the glass. However, the latter cannot be accurately calculated in this way, because of the existing of ionic bonds. In this paper, the constraints of the modifier ions in phosphate glasses were thoroughly investigated using the topological constraint theory. The results show that the constraints of the modifier ions are gradually increased with the addition of alkali oxides. Furthermore, an improved topological constraint theory for borophosphate glasses is proposed by taking the composition-dependent constraints of the network modifiers into consideration. The proposed theory is subsequently evaluated by analyzing the composition dependence of the glass transition temperature in alkali borophosphate glasses. This method is supposed to be extended to other similar glass systems containing alkali ions.

  11. Analysis on tritium permeation in tritium storage bed with gas flowing calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Hirofumi; Hayashi, Takumi; Suzuki, Takumi; Nishi, Masataka [Japan Atomic Energy Research Inst., Naka Fusion Research Establishment, Department of Fusion Engineering Research, Naka, Ibaraki (Japan); Yoshida, Hiroshi [Japan Atomic Energy Research Inst., Naka Fusion Research Establishment, ITER-Joint Centeral Team, Naka, Ibaraki (Japan)

    2000-10-01

    Tritium permeation amount in a tritium storage bed with gas flowing calorimetric was evaluated under a condition of new operation mode for International Thermonuclear Experimental Reactor (ITER). As a result, tritium permeation under the new operation mode was estimated to be about twice of that under the practical operation mode. This result show that it would be regardless in a view point of material control of tritium, however, it was suggested to be required additional tritium removal or evacuate system in a view points of safety control or performance of accountability or thermal insulating of the tritium storage bed. (author)

  12. Silicon Carbide as a tritium permeation barrier in tungsten plasma-facing components

    Science.gov (United States)

    Wright, G. M.; Durrett, M. G.; Hoover, K. W.; Kesler, L. A.; Whyte, D. G.

    2015-03-01

    The control of tritium inventory is of great importance in future fusion reactors, not only from a safety standpoint but also to maximize a reactor's efficiency. Due to the high mobility of hydrogenic species in tungsten (W) one concern is the loss of tritium from the system via permeation through the tungsten plasma-facing components (PFC). This can lead to loss of tritium through the cooling channels of the wall thereby mandating tritium monitoring and recovery methods for the cooling system of the first wall. The permeated tritium is then out of the fuel cycle and cannot contribute to energy production until it is recovered and recycled into the system.

  13. Deuterium permeation behavior of HTUPS4 steel with thermal oxidation layer

    International Nuclear Information System (INIS)

    Xu, Yu-Ping; Liu, Feng; Zhao, Si-Xiang; Li, Xiao-Chun; Wang, Jing; An, Zhong-Qing; Lu, Tao; Liu, Hao-Dong; Ding, Fang; Zhou, Hai-Shan; Luo, Guang-Nan

    2016-01-01

    The permeation behavior of creep-resistant, Al 2 O 3 -forming HTUPS austenitic stainless steels was studied using a gas driven permeation (GDP) device. The steel samples were first thermal oxidized at air condition, followed by GDP experiments. The permeability and diffusion coefficients of oxidized samples and bare 316L steels were derived and compared. In order to characterize the oxide layer, X-ray photoelectron spectroscopy was performed. An oxide layer with a thickness of 200 nm which mainly consists of Al 2 O 3 was detected.

  14. Concentration gradient driven molecular dynamics: a new method for simulations of membrane permeation and separation.

    Science.gov (United States)

    Ozcan, Aydin; Perego, Claudio; Salvalaglio, Matteo; Parrinello, Michele; Yazaydin, Ozgur

    2017-05-01

    In this study, we introduce a new non-equilibrium molecular dynamics simulation method to perform simulations of concentration driven membrane permeation processes. The methodology is based on the application of a non-conservative bias force controlling the concentration of species at the inlet and outlet of a membrane. We demonstrate our method for pure methane, ethane and ethylene permeation and for ethane/ethylene separation through a flexible ZIF-8 membrane. Results show that a stationary concentration gradient is maintained across the membrane, realistically simulating an out-of-equilibrium diffusive process, and the computed permeabilities and selectivity are in good agreement with experimental results.

  15. Nitride and carbide thin films as hydrogen permeation barrier on Manet steel

    International Nuclear Information System (INIS)

    Benamati, G.; Checchetto, R.; Bonelli, M.; Gratton, L.M.; Guzman, L.; Miotello, A.; Terlain, A.

    1995-01-01

    TiC / TiN bilayers, ∼ 1.2 μm thick, were deposited on Manet II steel by the ion beam assisted deposition technique to investigate the possible use of this ceramic coating as hydrogen barrier. Hydrogen permeation experiments in the temperature range 470-570 K showed indeed that this coating is a very efficient barrier to the hydrogen permeation being able to reduce the hydrogen flux up to two order of magnitude with respect to the uncoated steel. Preliminary compatibility tests between coated Manet II and Pb-17Li showed no attack of Pb-17Li to the steel. (orig.)

  16. Nitride and carbide thin films as hydrogen permeation barrier on MANET steel

    International Nuclear Information System (INIS)

    Benamati, G.

    1994-01-01

    TiC/TiN bilayers, - 1.2 μm thick, were deposited on Manet II steel by the ion beam assisted deposition technique to investigate the possible use of this ceramic coating as hydrogen barrier. Hydrogen permeation experiments in the temperature range 470-570 K showed indeed that this coating is a very efficient barrier to the hydrogen permeation being able to reduce the hydrogen flux up to two order of magnitude with respect to the uncoated steel. Preliminary compatibility tests between coated Manet II and Pb-17Li showed no attack of Pb-17Li to the steel. (author) 8 refs.; 2 figs.; 1 tab

  17. Implantation measurements to determine tritium permeation in first-wall structures

    International Nuclear Information System (INIS)

    Holland, D.F.; Causey, R.A.; Sattler, M.L.

    1983-01-01

    A principal safety concern for a D-T burning fusion reactor is release of tritium during routine operation. Tritium implantation into first-wall structures, and subsequent permeation into coolants, is potentially an important source of tritium loss. This paper reports on an experiment in which an ion accelerator was used to implant deuterium atoms in a stainless steel disk to simulate tritium implantation in first-wall structures. The permeation rate was measured under various operating conditions. These results were used in the TMAP computer code to determine potential tritium loss rates for fusion reactors

  18. Seismological Constraints on Geodynamics

    Science.gov (United States)

    Lomnitz, C.

    2004-12-01

    Earth is an open thermodynamic system radiating heat energy into space. A transition from geostatic earth models such as PREM to geodynamical models is needed. We discuss possible thermodynamic constraints on the variables that govern the distribution of forces and flows in the deep Earth. In this paper we assume that the temperature distribution is time-invariant, so that all flows vanish at steady state except for the heat flow Jq per unit area (Kuiken, 1994). Superscript 0 will refer to the steady state while x denotes the excited state of the system. We may write σ 0=(J{q}0ṡX{q}0)/T where Xq is the conjugate force corresponding to Jq, and σ is the rate of entropy production per unit volume. Consider now what happens after the occurrence of an earthquake at time t=0 and location (0,0,0). The earthquake introduces a stress drop Δ P(x,y,z) at all points of the system. Response flows are directed along the gradients toward the epicentral area, and the entropy production will increase with time as (Prigogine, 1947) σ x(t)=σ 0+α {1}/(t+β )+α {2}/(t+β )2+etc A seismological constraint on the parameters may be obtained from Omori's empirical relation N(t)=p/(t+q) where N(t) is the number of aftershocks at time t following the main shock. It may be assumed that p/q\\sim\\alpha_{1}/\\beta times a constant. Another useful constraint is the Mexican-hat geometry of the seismic transient as obtained e.g. from InSAR radar interferometry. For strike-slip events such as Landers the distribution of \\DeltaP is quadrantal, and an oval-shaped seismicity gap develops about the epicenter. A weak outer triggering maxiμm is found at a distance of about 17 fault lengths. Such patterns may be extracted from earthquake catalogs by statistical analysis (Lomnitz, 1996). Finally, the energy of the perturbation must be at least equal to the recovery energy. The total energy expended in an aftershock sequence can be found approximately by integrating the local contribution over

  19. Schroedinger operators and evolutionary strategies

    International Nuclear Information System (INIS)

    Asselmeyer, T.

    1997-01-01

    First we introduce a simple model for the description of evolutionary algorithms, which is based on 2nd order partial differential equations for the distribution function of the individuals. Then we turn to the properties of Boltzmann's and Darwin's strategy. the next chapter is dedicated to the mathematical properties of Schroedinger operators. Both statements on the spectral density and their reproducibility during the simulation are summarized. The remaining of this chapter are dedicated to the analysis of the kernel as well as the dependence of the Schroedinger operator on the potential. As conclusion from the results of this chapter we obtain the classification of the strategies in dependence of the fitness. We obtain the classification of the evolutionary strategies, which are described by a 2nd order partial differential equation, in relation to their solution behaviour. Thereafter we are employed with the variation of the mutation distribution

  20. Exponential Expansion in Evolutionary Economics

    DEFF Research Database (Denmark)

    Frederiksen, Peter; Jagtfelt, Tue

    2013-01-01

    This article attempts to solve current problems of conceptual fragmentation within the field of evolutionary economics. One of the problems, as noted by a number of observers, is that the field suffers from an assemblage of fragmented and scattered concepts (Boschma and Martin 2010). A solution...... to this problem is proposed in the form of a model of exponential expansion. The model outlines the overall structure and function of the economy as exponential expansion. The pictographic model describes four axiomatic concepts and their exponential nature. The interactive, directional, emerging and expanding...... concepts are described in detail. Taken together it provides the rudimentary aspects of an economic system within an analytical perspective. It is argued that the main dynamic processes of the evolutionary perspective can be reduced to these four concepts. The model and concepts are evaluated in the light...

  1. Preventive evolutionary medicine of cancers.

    Science.gov (United States)

    Hochberg, Michael E; Thomas, Frédéric; Assenat, Eric; Hibner, Urszula

    2013-01-01

    Evolutionary theory predicts that once an individual reaches an age of sufficiently low Darwinian fitness, (s)he will have reduced chances of keeping cancerous lesions in check. While we clearly need to better understand the emergence of precursor states and early malignancies as well as their mitigation by the microenvironment and tissue architecture, we argue that lifestyle changes and preventive therapies based in an evolutionary framework, applied to identified high-risk populations before incipient neoplasms become clinically detectable and chemoresistant lineages emerge, are currently the most reliable way to control or eliminate early tumours. Specifically, the relatively low levels of (epi)genetic heterogeneity characteristic of many if not most incipient lesions will mean a relatively limited set of possible adaptive traits and associated costs compared to more advanced cancers, and thus a more complete and predictable understanding of treatment options and outcomes. We propose a conceptual model for preventive treatments and discuss the many associated challenges.

  2. Passivity and Evolutionary Game Dynamics

    KAUST Repository

    Park, Shinkyu; Shamma, Jeff S.; Martins, Nuno C.

    2018-01-01

    This paper investigates an energy conservation and dissipation -- passivity -- aspect of dynamic models in evolutionary game theory. We define a notion of passivity using the state-space representation of the models, and we devise systematic methods to examine passivity and to identify properties of passive dynamic models. Based on the methods, we describe how passivity is connected to stability in population games and illustrate stability of passive dynamic models using numerical simulations.

  3. Passivity and Evolutionary Game Dynamics

    KAUST Repository

    Park, Shinkyu

    2018-03-21

    This paper investigates an energy conservation and dissipation -- passivity -- aspect of dynamic models in evolutionary game theory. We define a notion of passivity using the state-space representation of the models, and we devise systematic methods to examine passivity and to identify properties of passive dynamic models. Based on the methods, we describe how passivity is connected to stability in population games and illustrate stability of passive dynamic models using numerical simulations.

  4. [Evolutionary perspective in precocious puberty].

    Science.gov (United States)

    Hochberg, Ze'ev

    2014-10-01

    Pubertal development is subject to substantial heritability, but much variation remains to be explained, including fast changes over the last 150 years, that cannot be explained by changes of gene frequency in the population. This article discusses the influence of environmental factors to adjust maturational tempo in the service of fitness goals. Utilizing evolutionary development thinking (evo-devo), the author examines adolescence as an evolutionary life-history stage in its developmental context. The transition from the preceding stage of juvenility entails adaptive plasticity in response to energy resources, social needs of adolescence and maturation toward youth and adulthood. Using Belsky's evolutionary theory of socialization, I show that familial psychosocial environment during the infancy-childhood and childhood-juvenility transitions foster a fast life-history and reproductive strategy rather than early maturation being just a risk factor for aggression and delinquency. The implications of the evo-devo framework for theory building, illuminates new directions in the understanding of precocious puberty other than a diagnosis of a disease.

  5. Incorporating Development Into Evolutionary Psychology

    Directory of Open Access Journals (Sweden)

    David F. Bjorklund

    2016-09-01

    Full Text Available Developmental thinking is gradually becoming integrated within mainstream evolutionary psychology. This is most apparent with respect to the role of parenting, with proponents of life history theory arguing that cognitive and behavioral plasticity early in life permits children to select different life history strategies, with such strategies being adaptive solutions to different fitness trade-offs. I argue that adaptations develop and are based on the highly plastic nature of infants’ and children’s behavior/cognition/brains. The concept of evolved probabilistic cognitive mechanisms is introduced, defined as information processing mechanisms evolved to solve recurrent problems faced by ancestral populations that are expressed in a probabilistic fashion in each individual in a generation and are based on the continuous and bidirectional interaction over time at all levels of organization, from the genetic through the cultural. Early perceptual/cognitive biases result in behavior that, when occurring in a species-typical environment, produce continuous adaptive changes in behavior (and cognition, yielding adaptive outcomes. Examples from social learning and tool use are provided, illustrating the development of adaptations via evolved probabilistic cognitive mechanisms. The integration of developmental concepts into mainstream evolutionary psychology (and evolutionary concepts into mainstream developmental psychology will provide a clearer picture of what it means to be human.

  6. Testing evolutionary convergence on Europa

    Energy Technology Data Exchange (ETDEWEB)

    Chela-Flores, Julian [Instituto de Estudios Avanzados, Caracas (Venezuela); [Abdus Salam International Centre for Theoretical Physics, Trieste (Italy)

    2002-11-01

    A major objective in solar system exploration is the insertion of appropriate biology-oriented experiments in future missions. We discuss various reasons for suggesting that this type of research be considered a high priority for feasibility studies and, subsequently, for technological development of appropriate melters and submersibles. Based on numerous examples, we argue in favour of the assumption that Darwin's theory is valid for the evolution of life anywhere in the universe. We have suggested how to obtain preliminary insights into the question of the distribution of life in the universe. Universal evolution of intelligent behaviour is at the end of an evolutionary pathway, in which evolution of ion channels in the membrane of microorganisms occurs in its early stages. Further, we have argued that a preliminary test of this conjecture is feasible with experiments on the Europan surface or ocean, involving evolutionary biosignatures (ion channels). This aspect of the exploration for life in the solar system should be viewed as a complement to the astronomical approach for the search of evidence of the later stages of the evolutionary pathways towards intelligent behaviour. (author)

  7. Evolutionary ecology of virus emergence.

    Science.gov (United States)

    Dennehy, John J

    2017-02-01

    The cross-species transmission of viruses into new host populations, termed virus emergence, is a significant issue in public health, agriculture, wildlife management, and related fields. Virus emergence requires overlap between host populations, alterations in virus genetics to permit infection of new hosts, and adaptation to novel hosts such that between-host transmission is sustainable, all of which are the purview of the fields of ecology and evolution. A firm understanding of the ecology of viruses and how they evolve is required for understanding how and why viruses emerge. In this paper, I address the evolutionary mechanisms of virus emergence and how they relate to virus ecology. I argue that, while virus acquisition of the ability to infect new hosts is not difficult, limited evolutionary trajectories to sustained virus between-host transmission and the combined effects of mutational meltdown, bottlenecking, demographic stochasticity, density dependence, and genetic erosion in ecological sinks limit most emergence events to dead-end spillover infections. Despite the relative rarity of pandemic emerging viruses, the potential of viruses to search evolutionary space and find means to spread epidemically and the consequences of pandemic viruses that do emerge necessitate sustained attention to virus research, surveillance, prophylaxis, and treatment. © 2016 New York Academy of Sciences.

  8. Constraints on a generalized deceleration parameter from cosmic chronometers

    Science.gov (United States)

    Mamon, Abdulla Al

    2018-04-01

    In this paper, we have proposed a generalized parametrization for the deceleration parameter q in order to study the evolutionary history of the universe. We have shown that the proposed model can reproduce three well known q-parametrized models for some specific values of the model parameter α. We have used the latest compilation of the Hubble parameter measurements obtained from the cosmic chronometer (CC) method (in combination with the local value of the Hubble constant H0) and the Type Ia supernova (SNIa) data to place constraints on the parameters of the model for different values of α. We have found that the resulting constraints on the deceleration parameter and the dark energy equation of state support the ΛCDM model within 1σ confidence level at the present epoch.

  9. Hydrogen and deuterium permeation in copper alloys, copper--gold brazing alloys, gold, and the in situ growth of stable oxide permeation barriers

    International Nuclear Information System (INIS)

    Begeal, D.R.

    1978-01-01

    The deuterium permeation through several copper alloys has been measured over a temperature range of 550 to 830 K using the membrane technique. In some cases, the hydrogen permeability was also measured. The results were divided into three categories: common alloys, gold alloys, and stable oxide forming alloys. Common alloys which showed typical bulk metallic diffusion with litle change in the permeation activation energy as compared to copper (77 kJ/mol for D 2 ) were: (additions are in weight percent) 5% Sn, 2.3% U, 0.15% Zr, 4% Sn+4% Pb+4% Zn, 3% Si, and 7% Al+2% Fe. Compared to copper, the D 2 permeability at 573 K was reduced by factors of 2.0, 2.7, 4.5, 5.3, 5.9, and 7.0, respectively. A series of gold--copper alloys including pure gold, 80% Au, 50% Au, 49% Au, and 35% Au also showed typical bulk metallic diffusion with a trend of decreasing permeability (increasing activation energies for permeation) with increasing gold content. There were also pronounced inflections or shifts in the permeability at approx.370 0 C, or about the order--disorder transition for Cu 3 Au and CuAu, for the 80% and 50% alloys. Two alloys did not exhibit bulk metallic permeation behavior and the permeabiltiy was in fact controlled by surface oxide layers. It was found that a layer of beryllium oxide could be formed on Cu+2% Be and a layer of aluminum oxide could be formed on Cu+7% Al+2% Si. As compared to 0.25 mm-thick copper, the deuterium permeability at 500 0 C was reduced by a factor of approx.250 for Cu--Be and approx.1000 for Cu--Al--Si. The activation energies for deuterium permeation were 98 kJ/mol and 132 kJ/mol, respectively. The mechanism for the oxide growth is the high-temperature hydrogen reduction of nearby less stable oxides, simultaneous with oxidation of the active metal, Be or Al, by trace amounts of water in the hydrogen. Ion microprobe mass analysis identified the oxide layers as containing beryllium or aluminum but not containing copper

  10. Observational constraints on interstellar chemistry

    International Nuclear Information System (INIS)

    Winnewisser, G.

    1984-01-01

    The author points out presently existing observational constraints in the detection of interstellar molecular species and the limits they may cast on our knowledge of interstellar chemistry. The constraints which arise from the molecular side are summarised and some technical difficulties encountered in detecting new species are discussed. Some implications for our understanding of molecular formation processes are considered. (Auth.)

  11. Market segmentation using perceived constraints

    Science.gov (United States)

    Jinhee Jun; Gerard Kyle; Andrew Mowen

    2008-01-01

    We examined the practical utility of segmenting potential visitors to Cleveland Metroparks using their constraint profiles. Our analysis identified three segments based on their scores on the dimensions of constraints: Other priorities--visitors who scored the highest on 'other priorities' dimension; Highly Constrained--visitors who scored relatively high on...

  12. Fixed Costs and Hours Constraints

    Science.gov (United States)

    Johnson, William R.

    2011-01-01

    Hours constraints are typically identified by worker responses to questions asking whether they would prefer a job with more hours and more pay or fewer hours and less pay. Because jobs with different hours but the same rate of pay may be infeasible when there are fixed costs of employment or mandatory overtime premia, the constraint in those…

  13. An Introduction to 'Creativity Constraints'

    DEFF Research Database (Denmark)

    Onarheim, Balder; Biskjær, Michael Mose

    2013-01-01

    Constraints play a vital role as both restrainers and enablers in innovation processes by governing what the creative agent/s can and cannot do, and what the output can and cannot be. Notions of constraints are common in creativity research, but current contributions are highly dispersed due to n...

  14. Constraint Programming for Context Comprehension

    DEFF Research Database (Denmark)

    Christiansen, Henning

    2014-01-01

    A close similarity is demonstrated between context comprehension, such as discourse analysis, and constraint programming. The constraint store takes the role of a growing knowledge base learned throughout the discourse, and a suitable con- straint solver does the job of incorporating new pieces...

  15. COEVOLUTIONARY SEMANTICS OF TECHNOLOGICAL CIVILIZATION GENESIS AND EVOLUTIONARY RISK (BETWEEN THE BIOAESTHETICS AND BIOPOLITICS

    Directory of Open Access Journals (Sweden)

    V. T. Cheshko

    2016-12-01

    emotionally aesthetic image of «Self». In conclusion it should be noted that there is a causal link between the development of High Hume (NBIC technologies and the totality of the trend in the anthropological phenomenon of bio-power that permeates all the available human existence in modern civilization. As a result, there is a transformation of a contemporary social (man-made risk in the evolutionary civilization risk.

  16. Oxygen permeation flux through La1-ySryFeO3 limited by the carbon monoxide oxidation rate

    NARCIS (Netherlands)

    van Hassel, B.A.; van Hassel, B.A.; ten Elshof, Johan E.; Bouwmeester, Henricus J.M.

    1995-01-01

    The oxygen permeation flux through La1-ySryFeO3-δ (y = 0.1, 0.2) in a large oxygen partial pressure gradient (air/CO, CO2 mixture) was found to be limited by the carbon monoxide oxidation rate at the low oxygen partial pressure side of the membrane. The oxygen permeation flux through the membrane

  17. Liquid and Gas Permeation Studies on the Structure and Properties of Polyamide Thin-Film Composite Membranes

    KAUST Repository

    Duan, Jintang

    2014-01-01

    layer by gas adsorption and gas permeation measurements. Gas adsorption isotherms (N2 at 77K, CO2 at 273K) confirmed the microporous nature of PA in comparison with dense CTA and polysulfone materials. Gas permeation through the commercial PA

  18. Vocabulary Constraint on Texts

    Directory of Open Access Journals (Sweden)

    C. Sutarsyah

    2008-01-01

    Full Text Available This case study was carried out in the English Education Department of State University of Malang. The aim of the study was to identify and describe the vocabulary in the reading text and to seek if the text is useful for reading skill development. A descriptive qualitative design was applied to obtain the data. For this purpose, some available computer programs were used to find the description of vocabulary in the texts. It was found that the 20 texts containing 7,945 words are dominated by low frequency words which account for 16.97% of the words in the texts. The high frequency words occurring in the texts were dominated by function words. In the case of word levels, it was found that the texts have very limited number of words from GSL (General Service List of English Words (West, 1953. The proportion of the first 1,000 words of GSL only accounts for 44.6%. The data also show that the texts contain too large proportion of words which are not in the three levels (the first 2,000 and UWL. These words account for 26.44% of the running words in the texts.  It is believed that the constraints are due to the selection of the texts which are made of a series of short-unrelated texts. This kind of text is subject to the accumulation of low frequency words especially those of content words and limited of words from GSL. It could also defeat the development of students' reading skills and vocabulary enrichment.

  19. Efficient ethanol recovery from fermentation broths with integrated distillation-vapor permeation hybrid process

    Science.gov (United States)

    The energy demand of distillation-molecular sieve systems for ethanol recovery/dehydration can be significant, particularly for dilute solutions. An alternative hybrid process integrating vapor stripping (like a beer still) with vapor compression and a vapor permeation membrane s...

  20. Gas-permeation properties of poly(ethylene oxide) poly(butylene terephthalate block copolymers

    NARCIS (Netherlands)

    Metz, S.J.; Mulder, M.H.V.; Wessling, Matthias

    2004-01-01

    This paper reports the gas-permeation properties of poly(ethylene oxide) (PEO) poly(butylene terephthalate) (PBT) segmented multiblock copolymers. These block copolymers allow a precise structural modification by the amount of PBT and the PEO segment length, enabling a systematic study of the