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Sample records for group composition influences

  1. The influence of ethnic group composition on focus group discussions

    National Research Council Canada - National Science Library

    Greenwood, Nan; Ellmers, Theresa; Holley, Jess

    2014-01-01

    ... of importance to them in their own words [2]. They are particularly useful for gaining insight from minority ethnic groups [1, 3] because of their sensitivity to cultural variables [2, 4]. One of the main differences between focus groups and one-to-one interviews is the interaction between participants. Focus group participants can...

  2. Influence of Group Size and Group Composition on the Adhered Distance Headway

    NARCIS (Netherlands)

    Duives, D.C.; Daamen, W.; Hoogendoorn, S.P.

    2014-01-01

    Research into the influence of groups on pedestrian flow dynamics has been limited. Previous research found that group size influences the walking velocity of pedestrians within the group and as such the capacity the pedestrian infrastructure. This paper's aim is to provide quantitative insights

  3. Influence of chemical group composition of feedstock on results from catalytic cracking

    Energy Technology Data Exchange (ETDEWEB)

    Zhorov, Y.M.; Panchenkov, G.M.; Pivovarova, N.A.

    1983-01-01

    The work reported here is aimed at determining whether it is the distillation range of the chemical composition of the feed that influences the results obtained in catalytic cracking. For a quantitative evaluation of the influence of feedstock chemical composition on the cracking results, a linear equation relating the naptha yield to the contents of the group components is derived. The equation indicates that the ''light'' aromatics form considerable amounts of naptha, whereas the ''heavy'' aromatics retard the cracking. These relationships can be used in developing a mathematical model of the process and in selecting the severity of preliminary treating of catalytic cracking feedstocks.

  4. Correlation of maturity groups with seed composition in soybeans, as influenced by genotypic variation.

    Directory of Open Access Journals (Sweden)

    Maestri, Damián M.

    1998-12-01

    Full Text Available Seeds of 19 soybean cultivars (Glycine max (L. Merrill with maturity groups V, VI or VII were analyzed for proximate composition, fatty acids and sterols. Protein, oil, carbohydrate and ash contents varied between 344-463 g kg-1, 178-233 g kg-1, 234-338 g kg-1, and 40.0-49.3 g kg-1 of dry matter, respectively. Fatty acid profiles revealed that the major acids were palmitic (9.2-12.5%, oleic (17.7-22.1% and linoleic (53.6-56.9%. Linolenic acid ranged from 8.6 to 10.4%. Sitosterol (48.1-56.8% was the main component of the sterol fraction, followed by campesterol (18.4-21.7% and stigmasterol (13.4-18.0%. Statistically significant differences between genotypes were found for the majority of parameters evaluated, but there are not significant variations among maturity groups.

    Se analizaron la humedad, contenido en proteínas, carbohidratos, grasas y cenizas, y las composiciones en ácidos grasos y esteróles de las semillas de 19 cultivares de soja (Glycine max (L. Merrill con grupos de madurez V, VI o VIl. Los contenidos de proteínas, aceites, carbohidratos y cenizas variaron entre 344-463 g kg-1, 178-233 g kg-1, 234-338 g kg-1 y 40.0-49.3 g kg-1 de materia seca, respectivamente. Los ácidos grasos mayoritarios fueron palmítico (9.2-12.5%, oleico (17.7-22.1% y linoleico (53.6-56.9%. El porcentaje de ácido linolénico varió desde 8.6 hasta 10.4%. El principal componente de la fracción de esteroles del aceite fue el sitosterol (48.1-56.8%, seguido por el campesterol (18.4-21.7% y el estigmasterol (13.4-18.0%. Se encontraron diferencias estadísticamente significativas entre los genotipos para la mayoría de los parámetros evaluados, pero no hubo variaciones significativas entre grupos de madurez.

  5. Group Work and the Change of Obstacles over Time: The Influence of Learning Style and Group Composition

    Science.gov (United States)

    Soetanto, Danny; MacDonald, Matthew

    2017-01-01

    It is through working in groups that students develop cooperative learning skills and experience. However, group work activity often leads students into a difficult experience, especially for first-year students who are not familiar with group work activities at university. This study explores obstacles faced by first-year students during their…

  6. Influence of substituents and functional groups on the surface composition of ionic liquids.

    Science.gov (United States)

    Kolbeck, Claudia; Niedermaier, Inga; Deyko, Alexey; Lovelock, Kevin R J; Taccardi, Nicola; Wei, Wei; Wasserscheid, Peter; Maier, Florian; Steinrück, Hans-Peter

    2014-04-01

    We have performed a systematic study addressing the surface behavior of a variety of functionalized and non-functionalized ionic liquids (ILs). From angle-resolved X-ray photoelectron spectroscopy, detailed conclusions on the surface enrichment of the functional groups and the molecular orientation of the cations and anions is derived. The systems include imidazolium-based ILs methylated at the C2 position, a phenyl-functionalized IL, an alkoxysilane-functionalized IL, halo-functionalized ILs, thioether-functionalized ILs, and amine-functionalized ILs. The results are compared with the results for corresponding non-functionalized ILs where available. Generally, enrichment of the functional group at the surface is only observed for systems that have very weak interaction between the functional group and the ionic head groups.

  7. Liking and disliking minority-group classmates : Explaining the mixed findings for the influence of ethnic classroom composition on interethnic attitudes

    NARCIS (Netherlands)

    Stark, Tobias H.; Mäs, Michael; Flache, Andreas

    2015-01-01

    Research on the influence of the number of ethnic minority group classmates on majority group students' interethnic attitudes produced conflicting results. With data from 728 early adolescents, we found that the effect of the ethnic class composition depends on two opposing student-level mechanisms.

  8. Liking and disliking minority-group classmates : Explaining the mixed findings for the influence of ethnic classroom composition on interethnic attitudes

    NARCIS (Netherlands)

    Stark, Tobias H.; Maes, Michael; Flache, Andreas

    2015-01-01

    Research on the influence of the number of ethnic minority group classmates on majority group students’ interethnic attitudes produced conflicting results. With data from 728 early adolescents, we found that the effect of the ethnic class composition depends on two opposing student-level mechanisms.

  9. Children's Development within Peer Groups: Using Composite Social Maps to Identify Peer Networks and to Study Their Influences.

    Science.gov (United States)

    Kindermann, Thomas

    1998-01-01

    Presents a network-assessment technique and examples showing how group experiences affect children's behavior. Compares classical sociometry and the use of composite social maps. Discusses quantifying peer-network information, using peer-network profiles as context descriptors, and identifying change in children and networks. Shows that peer-group…

  10. How Group Size and Composition Influences the Effectiveness of Collaborative Screen-Based Simulation Training: A Study of Dental and Nursing University Students Learning Radiographic Techniques

    Directory of Open Access Journals (Sweden)

    Tor Söderström

    2012-12-01

    Full Text Available This study analyses how changes in the design of screen-based computer simulation training influence the collaborative training process. Specifically, this study examine how the size of a group and a group’s composition influence the way these tools are used. One case study consisted of 18+18 dental students randomized into either collaborative 3D simulation training or conventional collaborative training. The students worked in groups of three. The other case consisted of 12 nursing students working in pairs (partners determined by the students with a 3D simulator. The results showed that simulation training encouraged different types of dialogue compared to conventional training and that the communication patterns were enhanced in the nursing students ́ dyadic simulation training. The concrete changes concerning group size and the composition of the group influenced the nursing students’ engagement with the learning environment and consequently the communication patterns that emerged. These findings suggest that smaller groups will probably be more efficient than larger groups in a free collaboration setting that uses screen-based simulation training.

  11. Decreased group velocity in compositionally graded films.

    Science.gov (United States)

    Gao, Lei

    2006-03-01

    A theoretical formalism is presented that describes the group velocity of electromagnetic signals in compositionally graded films. The theory is first based on effective medium approximation or the Maxwell-Garnett approximation to obtain the equivalent dielectric function in a z slice. Then the effective dielectric tensor of the graded film is directly determined, and the group velocities for ordinary and extraordinary waves in the film are derived. It is found that the group velocity is sensitively dependent on the graded profile. For a power-law graded profile f(x)=ax(m), increasing m results in the decreased extraordinary group velocity. Such a decreased tendency becomes significant when the incident angle increases. Therefore the group velocity in compositionally graded films can be effectively decreased by our suitable adjustment of the total volume fraction, the graded profile, and the incident angle. As a result, the compositionally graded films may serve as candidate material for realizing small group velocity.

  12. Ectomycorrhizal Influence on Particle Size, Surface Structure, Mineral Crystallinity, Functional Groups, and Elemental Composition of Soil Colloids from Different Soil Origins

    Directory of Open Access Journals (Sweden)

    Yanhong Li

    2013-01-01

    Full Text Available Limited data are available on the ectomycorrhizae-induced changes in surface structure and composition of soil colloids, the most active portion in soil matrix, although such data may benefit the understanding of mycorrhizal-aided soil improvements. By using ectomycorrhizae (Gomphidius viscidus and soil colloids from dark brown forest soil (a good loam and saline-alkali soil (heavily degraded soil, we tried to approach the changes here. For the good loam either from the surface or deep soils, the fungus treatment induced physical absorption of covering materials on colloid surface with nonsignificant increases in soil particle size (P>0.05. These increased the amount of variable functional groups (O–H stretching and bending, C–H stretching, C=O stretching, etc. by 3–26% and the crystallinity of variable soil minerals (kaolinite, hydromica, and quartz by 40–300%. However, the fungus treatment of saline-alkali soil obviously differed from the dark brown forest soil. There were 12–35% decreases in most functional groups, 15–55% decreases in crystallinity of most soil minerals but general increases in their grain size, and significant increases in soil particle size (P<0.05. These different responses sharply decreased element ratios (C : O, C : N, and C : Si in soil colloids from saline-alkali soil, moving them close to those of the good loam of dark brown forest soil.

  13. Ectomycorrhizal influence on particle size, surface structure, mineral crystallinity, functional groups, and elemental composition of soil colloids from different soil origins.

    Science.gov (United States)

    Li, Yanhong; Wang, Huimei; Wang, Wenjie; Yang, Lei; Zu, Yuangang

    2013-01-01

    Limited data are available on the ectomycorrhizae-induced changes in surface structure and composition of soil colloids, the most active portion in soil matrix, although such data may benefit the understanding of mycorrhizal-aided soil improvements. By using ectomycorrhizae (Gomphidius viscidus) and soil colloids from dark brown forest soil (a good loam) and saline-alkali soil (heavily degraded soil), we tried to approach the changes here. For the good loam either from the surface or deep soils, the fungus treatment induced physical absorption of covering materials on colloid surface with nonsignificant increases in soil particle size (P > 0.05). These increased the amount of variable functional groups (O-H stretching and bending, C-H stretching, C=O stretching, etc.) by 3-26% and the crystallinity of variable soil minerals (kaolinite, hydromica, and quartz) by 40-300%. However, the fungus treatment of saline-alkali soil obviously differed from the dark brown forest soil. There were 12-35% decreases in most functional groups, 15-55% decreases in crystallinity of most soil minerals but general increases in their grain size, and significant increases in soil particle size (P soil colloids from saline-alkali soil, moving them close to those of the good loam of dark brown forest soil.

  14. Tsallis Entropy Composition and the Heisenberg Group

    Science.gov (United States)

    Kalogeropoulos, Nikos

    2013-03-01

    We present an embedding of the Tsallis entropy into the three-dimensional Heisenberg group, in order to understand the meaning of generalized independence as encoded in the Tsallis entropy composition property. We infer that the Tsallis entropy composition induces fractal properties on the underlying Euclidean space. Using a theorem of Milnor/Wolf/Tits/Gromov, we justify why the underlying configuration/phase space of systems described by the Tsallis entropy has polynomial growth for both discrete and Riemannian cases. We provide a geometric framework that elucidates Abe's formula for the Tsallis entropy, in terms the Pansu derivative of a map between sub-Riemannian spaces.

  15. Differences in the Activities of Eight Enzymes from Ten Soil Fungi and Their Possible Influences on the Surface Structure, Functional Groups, and Element Composition of Soil Colloids

    Science.gov (United States)

    Wang, Wenjie; Li, Yanhong; Wang, Huimei; Zu, Yuangang

    2014-01-01

    How soil fungi function in soil carbon and nutrient cycling is not well understood by using fungal enzymatic differences and their interactions with soil colloids. Eight extracellular enzymes, EEAs (chitinase, carboxymethyl cellulase, β-glucosidase, protease, acid phosphatase, polyphenol oxidase, laccase, and guaiacol oxidase) secreted by ten fungi were compared, and then the fungi that showed low and high enzymatic activity were co-cultured with soil colloids for the purpose of finding fungi-soil interactions. Some fungi (Gomphidius rutilus, Russula integra, Pholiota adiposa, and Geastrum mammosum) secreted 3–4 enzymes with weak activities, while others (Cyathus striatus, Suillus granulate, Phallus impudicus, Collybia dryophila, Agaricus sylvicola, and Lactarius deliciosus) could secret over 5 enzymes with high activities. The differences in these fungi contributed to the alterations of functional groups (stretching bands of O-H, N-H, C-H, C = O, COO- decreased by 11–60%, while P = O, C-O stretching, O-H bending and Si-O-Si stretching increased 9–22%), surface appearance (disappearance of adhesive organic materials), and elemental compositions (11–49% decreases in C1s) in soil colloids. Moreover, more evident changes were generally in high enzymatic fungi (C. striatus) compared with low enzymatic fungi (G. rutilus). Our findings indicate that inter-fungi differences in EEA types and activities might be responsible for physical and chemical changes in soil colloids (the most active component of soil matrix), highlighting the important roles of soil fungi in soil nutrient cycling and functional maintenance. PMID:25398013

  16. Differences in the activities of eight enzymes from ten soil fungi and their possible influences on the surface structure, functional groups, and element composition of soil colloids.

    Science.gov (United States)

    Wang, Wenjie; Li, Yanhong; Wang, Huimei; Zu, Yuangang

    2014-01-01

    How soil fungi function in soil carbon and nutrient cycling is not well understood by using fungal enzymatic differences and their interactions with soil colloids. Eight extracellular enzymes, EEAs (chitinase, carboxymethyl cellulase, β-glucosidase, protease, acid phosphatase, polyphenol oxidase, laccase, and guaiacol oxidase) secreted by ten fungi were compared, and then the fungi that showed low and high enzymatic activity were co-cultured with soil colloids for the purpose of finding fungi-soil interactions. Some fungi (Gomphidius rutilus, Russula integra, Pholiota adiposa, and Geastrum mammosum) secreted 3-4 enzymes with weak activities, while others (Cyathus striatus, Suillus granulate, Phallus impudicus, Collybia dryophila, Agaricus sylvicola, and Lactarius deliciosus) could secret over 5 enzymes with high activities. The differences in these fungi contributed to the alterations of functional groups (stretching bands of O-H, N-H, C-H, C = O, COO- decreased by 11-60%, while P = O, C-O stretching, O-H bending and Si-O-Si stretching increased 9-22%), surface appearance (disappearance of adhesive organic materials), and elemental compositions (11-49% decreases in C1s) in soil colloids. Moreover, more evident changes were generally in high enzymatic fungi (C. striatus) compared with low enzymatic fungi (G. rutilus). Our findings indicate that inter-fungi differences in EEA types and activities might be responsible for physical and chemical changes in soil colloids (the most active component of soil matrix), highlighting the important roles of soil fungi in soil nutrient cycling and functional maintenance.

  17. Friendship Group Composition and Juvenile Institutional Misconduct.

    Science.gov (United States)

    Reid, Shannon E

    2017-02-01

    The present study examines both the patterns of friendship networks and how these network characteristics relate to the risk factors of institutional misconduct for incarcerated youth. Using friendship networks collected from males incarcerated with California's Division of Juvenile Justice (DJJ), latent profile analysis was utilized to create homogeneous groups of friendship patterns based on alter attributes and network structure. The incarcerated youth provided 144 egocentric networks reporting 558 social network relationships. Latent profile analysis identified three network profiles: expected group (67%), new breed group (20%), and model citizen group (13%). The three network profiles were integrated into a multiple group analysis framework to examine the relative influence of individual-level risk factors on their rate of institutional misconduct. The analysis finds variation in predictors of institutional misconduct across profile types. These findings suggest that the close friendships of incarcerated youth are patterned across the individual characteristics of the youth's friends and that the friendship network can act as a moderator for individual risk factors for institutional misconduct.

  18. 7 CFR 3411.11 - Composition of peer review groups.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Composition of peer review groups. 3411.11 Section... PROGRAM Scientific Peer Review of Research Grant Applications § 3411.11 Composition of peer review groups. (a) Peer review group members and ad hoc reviewers will be selected based upon their training...

  19. 7 CFR 3415.11 - Composition of peer review groups.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Composition of peer review groups. 3415.11 Section... PROGRAM Scientific Peer Review of Research Grant Applications § 3415.11 Composition of peer review groups. (a) Peer review group members and ad hoc reviewers will be selected based upon their training...

  20. 7 CFR 3401.13 - Composition of peer review groups.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Composition of peer review groups. 3401.13 Section... Peer Review of Research Applications for Funding § 3401.13 Composition of peer review groups. Peer review group members will be selected based upon their training or experience in relevant scientific...

  1. Modeling of Internet Influence on Group Emotion

    Science.gov (United States)

    Czaplicka, Agnieszka; Hołyst, Janusz A.

    Long-range interactions are introduced to a two-dimensional model of agents with time-dependent internal variables ei = 0, ±1 corresponding to valencies of agent emotions. Effects of spontaneous emotion emergence and emotional relaxation processes are taken into account. The valence of agent i depends on valencies of its four nearest neighbors but it is also influenced by long-range interactions corresponding to social relations developed for example by Internet contacts to a randomly chosen community. Two types of such interactions are considered. In the first model the community emotional influence depends only on the sign of its temporary emotion. When the coupling parameter approaches a critical value a phase transition takes place and as result for larger coupling constants the mean group emotion of all agents is nonzero over long time periods. In the second model the community influence is proportional to magnitude of community average emotion. The ordered emotional phase was here observed for a narrow set of system parameters.

  2. Group Composition Affecting Student Interaction and Achievement: Instructors' Perspectives

    Science.gov (United States)

    Lei, Simon A.; Kuestermeyer, Bailey N.; Westmeyer, Kara A.

    2010-01-01

    Multiple research studies have been conducted that focus on various uses of collaborative learning in and out of the classroom in higher education institutions. The purpose of this article is to review previously published literature regarding group composition and how it affects student interaction and achievement. Group composition research has…

  3. 42 CFR 52h.4 - Composition of peer review groups.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Composition of peer review groups. 52h.4 Section... PEER REVIEW OF RESEARCH GRANT APPLICATIONS AND RESEARCH AND DEVELOPMENT CONTRACT PROJECTS § 52h.4 Composition of peer review groups. (a) To the extent applicable, the selection and appointment of members...

  4. 7 CFR 3400.11 - Composition of peer review groups.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Composition of peer review groups. 3400.11 Section..., EDUCATION, AND EXTENSION SERVICE, DEPARTMENT OF AGRICULTURE SPECIAL RESEARCH GRANTS PROGRAM Scientific Peer Review of Research Grant Applications § 3400.11 Composition of peer review groups. (a) Peer review...

  5. Influence of tobacco type on smoke composition

    Energy Technology Data Exchange (ETDEWEB)

    Griest, W.H.; Guerin, M.R.

    1977-01-01

    Cigarette smoke quantity and composition is affected by both the physical properties and chemical nature of the tobacco. Flue-cured tobacco exhibits a greater density than does Burley which results in a larger number of standard puffs per cigarette for the former and, thus, increased per cigarette deliveries of most smoke constituents. The greater carbohydrate and polyphenolic content of flue-cured tobaccos contributes to an increased yield of acidic constituents in the smoke. The increased nitrogenous component of Burley tobacco leads to a more alkaline smoke and one enriched in oxides of nitrogen. A quantitative elucidation of the relationship between tobacco type and smoke composition from literature results is complicated by the large number of variables influencing smoke composition which are generally unspecified in the reports. Smokes from cigaretts containing straight Burley and straight Bright tobaccos are compared based on analytical results from this laboratory. With few exceptions, smoke composition is often influenced more by processing variables and agronomic practices than by general tobacco ''type.'' 6 tables.

  6. Moderating effects of group status, cohesion, and ethnic composition on socialization of aggression in children's peer groups.

    Science.gov (United States)

    Shi, Bing; Xie, Hongling

    2014-09-01

    We explored the effects of 3 group features (i.e., status, cohesion, and ethnic composition) on socialization processes of aggression in early adolescents' natural peer social groups. Gender differences in these effects were also determined. A total of 245 seventh-grade individuals belonging to 65 peer groups were included in the analyses. All 3 group features moderated the strength of group socialization on physical aggression with the exception of group status on girls' physical aggression. Stronger socialization of physical aggression occurred in higher status, more cohesive, or ethnically more homogeneous groups. In contrast, only group cohesion moderated the strength of group socialization on social aggression among girls. These findings suggest that somewhat different processes may be involved in peer group influences on different forms of aggression. Future intervention and prevention efforts for adolescent aggression should consider peer group membership and group features simultaneously.

  7. Lipid bilayer composition influences small multidrug transporters

    Directory of Open Access Journals (Sweden)

    Curnow Paul

    2008-11-01

    Full Text Available Abstract Background Membrane proteins are influenced by their surrounding lipids. We investigate the effect of bilayer composition on the membrane transport activity of two members of the small multidrug resistance family; the Escherichia coli transporter, EmrE and the Mycobacterium tuberculosis, TBsmr. In particular we address the influence of phosphatidylethanolamine and anionic lipids on the activity of these multidrug transporters. Phosphatidylethanolamine lipids are native to the membranes of both transporters and also alter the lateral pressure profile of a lipid bilayer. Lipid bilayer lateral pressures affect membrane protein insertion, folding and activity and have been shown to influence reconstitution, topology and activity of membrane transport proteins. Results Both EmrE and TBsmr are found to exhibit a similar dependence on lipid composition, with phosphatidylethanolamine increasing methyl viologen transport. Anionic lipids also increase transport for both EmrE and TBsmr, with the proteins showing a preference for their most prevalent native anionic lipid headgroup; phosphatidylglycerol for EmrE and phosphatidylinositol for TBsmr. Conclusion These findings show that the physical state of the membrane modifies drug transport and that substrate translocation is dependent on in vitro lipid composition. Multidrug transport activity seems to respond to alterations in the lateral forces exerted upon the transport proteins by the bilayer.

  8. Does Group Composition Affect Learning by Invention?

    Science.gov (United States)

    Wiedmann, Michael; Leach, Ryan C.; Rummel, Nikol; Wiley, Jennifer

    2012-01-01

    Schwartz and Martin ("Cogn Instr" 22:129-184, 2004) as well as Kapur ("Instr Sci", this issue, 2012) have found that students can be better prepared to learn about mathematical formulas when they try to invent them in small groups before receiving the canonical formula from a lesson. The purpose of the present research was to investigate how the…

  9. Sex Composition and Leadership in Small Groups

    Science.gov (United States)

    Eskilson, Arlene; Wiley, Mary G.

    1976-01-01

    Leader behavior of males and females in three-person experimental groups was investigated in varying contexts. Deviating from stereotypical expectations, females reacted to "achieved" leader role by relatively intense leadership efforts, a response predicted for males but not females. Also, both sexes addressed more directive behavior toward own…

  10. Does Group Composition Affect Learning by Invention?

    Science.gov (United States)

    Wiedmann, Michael; Leach, Ryan C.; Rummel, Nikol; Wiley, Jennifer

    2012-01-01

    Schwartz and Martin ("Cogn Instr" 22:129-184, 2004) as well as Kapur ("Instr Sci", this issue, 2012) have found that students can be better prepared to learn about mathematical formulas when they try to invent them in small groups before receiving the canonical formula from a lesson. The purpose of the present research was to investigate how the…

  11. Influence of prepolymer composition on polyurethane morphology

    Science.gov (United States)

    Krishnamoorthy, Jayaraman; Jeong, Young Gyu; Hashida, Tomoko; Hsu, Shaw Ling

    2004-03-01

    Polyurethane chemistry is one of the most studied subjects. Yet many aspects remain unexplained. Polyurethanes are synthesized by the reaction of diisocyanate with diol in the presence of nucleophilic catalysts. Polyurethane prepolymers are obtained by reacting the polyester diol / polyether diol with diisocyanate, with [NCO] / [OH] > 1, resulting in isocyanate-terminated polyester/polyether mixture. Prepolymers thus synthesized can be cured at a later stage to realize various morphologies and structures. Though the initial composition and the final morphology are known, little is known about the intermediate prepolymer mixture. Due to the different reactivity of primary and secondary hydroxyl groups in the polyester and polyether towards isocyanate, prepolymer has a non-random distribution in terms of composition as blends and copolymers. Our aim is to characterize the prepolymer by different techniques and study how the different prepolymer composition, with varying polyester and polyether ratio, affects the morphology and phase separation kinetics of the final product.

  12. Influence of silanization and filler fraction on aged dental composites.

    Science.gov (United States)

    Lin, C T; Lee, S Y; Keh, E S; Dong, D R; Huang, H M; Shih, Y H

    2000-11-01

    The effect of silanization and filler fraction on the mechanical properties of aged dental composites was investigated. Experimental composites (75/25 Bis-GMA/TEGDMA resin reinforced with 0, 12.6, 30.0, and 56.5 vol% 8 microm silanized/unsilanized BaSiO6) were fabricated into 4.7 mm diameter x 2.2 mm thick discs and 3.5 mm diameter x 7.3 mm thick discs for diametral tensile and compressive tests, respectively. The effect of immersion in 75% ethanol at 37 degrees C for 0-30 days on the diametral tensile strength (DTS) and compressive strength (CS) of the samples was evaluated and analysed by ANOVA and Tukey LSD test. The fracture interface between filler and resin matrix was then examined by scanning electron microscope. Results and subsequent statistical evidence from DTS (18.6+/-7.6 MPa, silanized versus 11.7+/-2.6 MPa, unsilanized) and CS (85.1+/-29.7 MPa, silanized versus 56.0+/-11.3 MPa, unsilanized) strongly implies that silanization may greatly enhance the mechanical properties of the resin composites. Furthermore, it also shows that both DTS and CS increased proportionally as the filler fraction of the composites increased. However, in the unsilanized groups, DTS decreased (up to 40%) as the filler fraction increased, and CS showed no relevance to the filler fraction at all. As for the influence of aging, it was found that both DTS and CS showed a significant decrease after immersion in 75% ethanol, and silanization heavily correlated with the filler fraction of aged-resin composites. Microscopic examination of the fractured samples showed that failure primarily occurred within the resin matrix per se for silanized composites and adjacent to the filler particles for unsilanized composites. All the evidence points to the conclusion that mechanical properties of aged-resin composites can be greatly influenced by silanization and the filler fraction.

  13. The effect of group composition and age on social behavior and competition in groups of weaned dairy calves.

    Science.gov (United States)

    Faerevik, G; Jensen, M B; Bøe, K E

    2010-09-01

    The objective of the present study was to investigate how group composition affects behavior and weight gain of newly weaned dairy calves and how age within heterogeneous groups affects behavior and competition. Seventy-two calves were introduced into 6 groups of 12 calves, of which 3 groups were homogeneous and 3 groups were heterogeneous (including 6 young and 6 old calves). The 9.8 mx9.5 m large experimental pen had 4 separate lying areas as well as a feeding area. Behavior and subgrouping were recorded on d 1, 7, and 14 after grouping, and calves were weighed before and after the experimental period of 14 d. Analysis of the effect of group composition on behavior and weight gain included young calves in heterogeneous groups and calves in homogeneous groups within the same age range at grouping (30 to 42 d). Irrespective of group composition, time spent feeding and lying increased, whereas time spent active decreased from d 1 to 7. In homogeneous groups, calves were more explorative on d 1 after grouping. Finally, calves in homogeneous groups had a higher average daily weight gain than calves in heterogeneous groups. Analysis of the effect of age included young and old calves of heterogeneous groups. Young calves were less explorative than old calves. Young calves were more active than old calves on d 1 but less active on d 7. Time spent lying and lying alone increased over time. More displacements from the feed manger were performed by old calves than by young calves. An analysis including all calves in both homogeneous and heterogeneous groups showed that when lying, calves were evenly distributed on the 4 lying areas and formed subgroups of on average 3 calves. In conclusion, age heterogeneity leads to increased competition, which may have a negative influence on the young calves' performance.

  14. Process and Outcome in Encounter Groups: The Effects of Group Composition.

    Science.gov (United States)

    Stava, Lawrence J.; Bednar, Richard L.

    1979-01-01

    Examines relative efficacy of dissonance theory and interpersonal attraction theory over random composition in composing groups that will work best in group therapy. Treatment variables were a tape-recorded treatment condition, a placebo condition, and a no-treatment control condition. No clear support for either theory of group support was found.…

  15. Structure and content of competitive group compositions in sports aerobics

    Directory of Open Access Journals (Sweden)

    Tetiana Moshenska

    2017-02-01

    Full Text Available Purpose: to make the analysis of modern competitive group compositions in sports aerobics. Material & Methods: pedagogical, sociological and methods of mathematical statistics were used. 10 coaches took part in the experimental part; analysis of protocols and video records of competitions of the aged category of children of 9–11 years old, who perform in the nomination of triplets and quintuples (group exercises, is carried out. Results: the content of competitive compositions and the allocated indicators are studied which defined it. Conclusions: the basic structural elements, which characterize competitive compositions, are allocated. Their components, quantity and time of performance are defined. It is established that variety of aerobic contents, spaces, and means of registration, musical compliance and logicality of creation of the whole competitive composition at high quality of performance characterizes teams – winners.

  16. The effect of group composition and age on social behaviour and competition in groups of weaned dairy calves

    DEFF Research Database (Denmark)

    Færevik, G.; Jensen, Margit Bak; Bøe, K. E.

    2010-01-01

    including all calves in both homogeneous and heterogeneous groups showed that when lying, calves were evenly distributed on the 4 lying areas and formed subgroups of on average 3 calves. In conclusion, age heterogeneity leads to increased competition, which may have a negative influence on the young calves......The objective of the present study was to investigate how group composition affects behavior and weight gain of newly weaned dairy calves and how age within heterogeneous groups affects behavior and competition. Seventy-two calves were introduced into 6 groups of 12 calves, of which 3 groups were...... homogeneous and 3 groups were heterogeneous (including 6 young and 6 old calves). The 9.8 m × 9.5 m large experimental pen had 4 separate lying areas as well as a feeding area. Behavior and subgrouping were recorded on d 1, 7, and 14 after grouping, and calves were weighed before and after the experimental...

  17. Diet may influence the oral microbiome composition in cats

    National Research Council Canada - National Science Library

    Adler, Christina J; Malik, Richard; Browne, Gina V; Norris, Jacqueline M

    2016-01-01

    .... There is a complete lack of information about how diet (composition and texture) affects the feline oral microbiome, the composition of which may influence oral health and the development of periodontal disease...

  18. Urban greenness influences airborne bacterial community composition.

    Science.gov (United States)

    Mhuireach, Gwynne; Johnson, Bart R; Altrichter, Adam E; Ladau, Joshua; Meadow, James F; Pollard, Katherine S; Green, Jessica L

    2016-11-15

    Urban green space provides health benefits for city dwellers, and new evidence suggests that microorganisms associated with soil and vegetation could play a role. While airborne microorganisms are ubiquitous in urban areas, the influence of nearby vegetation on airborne microbial communities remains poorly understood. We examined airborne microbial communities in parks and parking lots in Eugene, Oregon, using high-throughput sequencing of the bacterial 16S rRNA gene on the Illumina MiSeq platform to identify bacterial taxa, and GIS to measure vegetation cover in buffer zones of different diameters. Our goal was to explore variation among highly vegetated (parks) versus non-vegetated (parking lots) urban environments. A secondary objective was to evaluate passive versus active collection methods for outdoor airborne microbial sampling. Airborne bacterial communities from five parks were different from those of five parking lots (p=0.023), although alpha diversity was similar. Direct gradient analysis showed that the proportion of vegetated area within a 50m radius of the sampling station explained 15% of the variation in bacterial community composition. A number of key taxa, including several Acidobacteriaceae were substantially more abundant in parks, while parking lots had higher relative abundance of Acetobacteraceae. Parks had greater beta diversity than parking lots, i.e. individual parks were characterized by unique bacterial signatures, whereas parking lot communities tended to be similar to each other. Although parks and parking lots were selected to form pairs of nearby sites, spatial proximity did not appear to affect compositional similarity. Our results also showed that passive and active collection methods gave comparable results, indicating the "settling dish" method is effective for outdoor airborne sampling. This work sets a foundation for understanding how urban vegetation may impact microbial communities, with potential implications for designing

  19. Composite group of explicit Runge-Kutta methods

    Science.gov (United States)

    Hamid, Fatin Nadiah Abd; Rabiei, Faranak; Ismail, Fudziah

    2016-06-01

    In this paper,the composite groups of Runge-Kutta (RK) method are proposed. The composite group of RK method of third and second order, RK3(2) and fourth and third order RK4(3) base on classical Runge-Kutta method are derived. The proposed methods are two-step in nature and have less number of function evaluations compared to the existing Runge-Kutta method. The order conditions up to order four are obtained using rooted trees and composite rule introduced by J. C Butcher. The stability regions of RK3(2) and RK4(3) methods are presented and initial value problems of first order ordinary differential equations are carried out. Numerical results are compared with existing Runge-Kutta method.

  20. Intelligence and Personal Influence in Groups: Four Nonlinear Models.

    Science.gov (United States)

    Simonton, Dean Keith

    1985-01-01

    Four models are developed to provide a conceptual basis for a curvilinear relation between intelligence and an individual's influence over group members. The models deal with influence and percentile placement in intelligence, comprehension by potential followers, vulnerability to rival intellects, and correlation between mean group IQ and the…

  1. Protecting groups in carbohydrate chemistry: influence on stereoselectivity of glycosylations.

    Science.gov (United States)

    Guo, Jian; Ye, Xin-Shan

    2010-10-20

    Saccharides are polyhydroxy compounds, and their synthesis requires complex protecting group manipulations. Protecting groups are usually used to temporarily mask a functional group which may interfere with a certain reaction, but protecting groups in carbohydrate chemistry do more than protecting groups usually do. Particularly, protecting groups can participate in reactions directly or indirectly, thus affecting the stereochemical outcomes, which is important for synthesis of oligosaccharides. Herein we present an overview of recent advances in protecting groups influencing stereoselectivity in glycosylation reactions, including participating protecting groups, and conformation-constraining protecting groups in general.

  2. Water Group Composition Near the Orbit of Enceladus

    Science.gov (United States)

    Williams, J. D.; Delamere, P. A.; Bagenal, F.; Reisenfeld, D.; Fleshman, R.

    2008-12-01

    We present magnetospheric ion composition results from the Cassini CAPS IMS instrument. The data set is averaged over a four year period. Data from the equatorial plane are selected and binned into radial, local time and longitude bins with a focus on radial distances between 3-10 Saturn radii. The data analysis process necessitates fitting the instrument response functions to the raw data and so methods of assessment of data uncertainty are also presented. Water group ions (O+, OH+, H2O+, H3O+; or collectively W+), presented as mixing ratios dominate over H+ in this radial range and O+ is the dominant water group species. Temporal variations within the study period are presented. The energy distribution of the ion composition is also examined and the flow velocity is compared to the corotation velocity of the plasma.

  3. The impact of group composition and attitudes towards diversity on anticipated outcomes of diversity in groups

    NARCIS (Netherlands)

    van Oudenhoven-van der Zee, Karen; Paulus, Paul; Vos, Menno; Parthasarathy, Niveditha

    2009-01-01

    In two studies, students evaluated group pictures of workgroups of varying ethnic and gender composition with respect to anticipated affective and productive outcomes. The impact of level of diversity, faultlines and individual differences in diversity attitudes on anticipated outcomes were examined

  4. Gender and Group Composition in Small Task Groups Using Computer-Mediated Communication.

    Science.gov (United States)

    Savicki, Victor; And Others

    1996-01-01

    Gender and group composition variables in a computer-mediated communication context are examined. Subjects were 36 undergraduate male and female psychology students. Findings are analyzed in terms of choice of language; participation; satisfaction; and interpersonal conflict. Ten tables present study results. (Author/AEF)

  5. The impact of group composition and attitudes towards diversity on anticipated outcomes of diversity in groups

    NARCIS (Netherlands)

    van Oudenhoven-van der Zee, Karen; Paulus, Paul; Vos, Menno; Parthasarathy, Niveditha

    2009-01-01

    In two studies, students evaluated group pictures of workgroups of varying ethnic and gender composition with respect to anticipated affective and productive outcomes. The impact of level of diversity, faultlines and individual differences in diversity attitudes on anticipated outcomes were examined

  6. Influence of group member familiarity on online collaborative learning

    NARCIS (Netherlands)

    Janssen, Jeroen; Erkens, Gijsbert; Kirschner, Paul A.; Kanselaar, Gellof

    2010-01-01

    Janssen, J. J. H. M., Erkens, G., Kirschner, P. A., & Kanselaar, G. (2009). Influence of group member familiarity on online collaborative learning computers in human behaviour. Computers in Human Behavior, 25, 261-270.

  7. Perception of Groups, Size of Opposition, and Social Influence

    Science.gov (United States)

    Wilder, David A.

    1977-01-01

    Two experiments investigated the relationship between social influence and the number of persons attempting influence. Findings suggest that the manner in which persons are initially organized into groups and aggregates of individuals affects their persuasive impact on observers. (Editor/RK)

  8. Group composition effects on aggressive interpack interactions of gray wolves in Yellowstone National Park

    Science.gov (United States)

    Cassidy, Kira A.; MacNulty, Daniel R.; Stahler, Daniel R.; Smith, Douglas W.; Mech, L. David

    2015-01-01

    Knowledge of characteristics that promote group success during intraspecific encounters is key to understanding the adaptive advantages of sociality for many group-living species. In addition, some individuals in a group may be more likely than others to influence intergroup conflicts, a relatively neglected idea in research on social animals. Here we use observations of aggressive interactions between wolf (Canis lupus) packs over an extended period and use pack characteristics to determine which groups had an advantage over their opponents. During 16 years of observation in Yellowstone National Park from 1995 to 2010, we documented 121 interpack aggressive interactions. We recorded pack sizes, compositions, and spatial orientation related to residency to determine their effects on the outcomes of interactions between packs. Relative pack size (RPS) improved the odds of a pack displacing its opponent. However, pack composition moderated the effect of RPS as packs with relatively more old members (>6.0 years old) or adult males had higher odds of winning despite a numerical disadvantage. The location of the interaction with respect to pack territories had no effect on the outcome of interpack interactions. Although the importance of RPS in successful territorial defense suggests the evolution and maintenance of group living may be at least partly due to larger packs’ success during interpack interactions, group composition is also an important factor, highlighting that some individuals are more valuable than others during interpack conflicts.

  9. The Purpose of Tutorial Groups: Social Influence and the Group as Means and Objective

    Science.gov (United States)

    Rosander, Michael; Chiriac, Eva Hammar

    2016-01-01

    The aim of this study was to investigate how first-year students view the purpose of tutorial groups in problem-based learning. In all, 147 students from 24 groups participated, providing 399 statements. Data were analysed using thematic analysis. The results showed a focus on both learning and social influence. Learning involved the tutorial as…

  10. Group Influences on Young Adult Warfighters’ Risk Taking

    Science.gov (United States)

    2016-12-01

    Award Number: W81XWH-12-2-0124, HRPO Log Number A-17574 TITLE: "Group Influences on Young Adult Warfighters’ Risk -Taking" CONTRACTING ORGANIZATION...PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE December 2016 2. REPORT TYPE Final 3. DATES COVERED 30Sep2012 - 29Sep2016 4...TITLE AND SUBTITLE Group Influences on Young Adult Warfighters’ Risk -Taking 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT

  11. Four-dimensional space groups for pedestrians: composite structures.

    Science.gov (United States)

    Sun, Junliang; Lee, Stephen; Lin, Jianhua

    2007-10-01

    Higher-dimensional crystals have been studied for the last thirty years. However, most practicing chemists, materials scientists, and crystallographers continue to eschew the use of higher-dimensional crystallography in their work. Yet it has become increasingly clear in recent years that the number of higher-dimensional systems continues to grow from hundreds to as many as a thousand different compounds. Part of the problem has to do with the somewhat opaque language that has developed over the past decades to describe higher-dimensional systems. This language, while well-suited to the specialist, is too sophisticated for the neophyte wishing to enter the field, and as such can be an impediment. This Focus Review hopes to address this issue. The goal of this article is to show the regular chemist or materials scientist that knowledge of regular 3D crystallography is all that is really necessary to understand 4D crystal systems. To this end, we have couched higher-dimensional composite structures in the language of ordinary 3D crystals. In particular, we developed the principle of complementarity, which allows one to identify correctly 4D space groups solely from examination of the two 3D components that make up a typical 4D composite structure.

  12. Intensive chemistry seminar, group ability composition, and students' achievement

    Science.gov (United States)

    Fakhreddine, Fatima Hassan

    Intensive Chemistry Seminar (ICS) is an optional, supplemental, honors-level program for chemistry and biochemistry majors. The program emphasizes academic excellence in a challenging yet supportive chemistry rich learning environment that brings together a community of freshmen sharing the same interests. At the heart of ICS are intensive discussion sessions where students work in small groups on worksheets of carefully chosen problems that are direct application of the concepts covered in the main general chemistry course. Central to the success of such learning environment are interactions among students. A key element affecting the depth of such interactions is the relative ability levels of group members. The main focus of this study is to investigate the relationship between. group ability composition and chemistry knowledge acquisition within the ICS sessions. However, the study also compares the achievement of the ICS students with achievement of the non-ICS students. Our data analyses show that chemistry knowledge acquisition within the ICS sessions was significantly enhanced when group members' selection occurred from a Zone of Proximal Development perspective. Our analyses show that students' attitude toward the ICS is overwhelmingly positive and that the benefits of the program extend beyond academic achievement. In practice, our significant results have important applications in college level, cooperative learning practices with objectives similar to those of ICS. Our results show that Vygotsky's ZPD theory seems to be very appropriate for the design and application of cooperative learning environments. Finally, the significant beneficial outcomes of the ICS program should strongly support its integration into the general chemistry I and II majors' sections curriculums.

  13. Influence of functional groups on charge transport in molecular junctions

    DEFF Research Database (Denmark)

    Mowbray, Duncan; Jones, Glenn; Thygesen, Kristian Sommer

    2008-01-01

    Using density functional theory (DFT), we analyze the influence of five classes of functional groups, as exemplified by NO2, OCH3, CH3, CCl3, and I, on the transport properties of a 1,4-benzenedithiolate (BDT) and 1,4-benzenediamine (BDA) molecular junction with gold electrodes. Our analysis...... demonstrates how ideas from functional group chemistry may be used to engineer a molecule's transport properties, as was shown experimentally and using a semiempirical model for BDA [Nano Lett. 7, 502 (2007)]. In particular, we show that the qualitative change in conductance due to a given functional group can...

  14. Brokering health policy: coalitions, parties, and interest group influence.

    Science.gov (United States)

    Heaney, Michael T

    2006-10-01

    Assuming a position as broker between disconnected interests is one way for an interest group to influence the making of federal health policy. This study demonstrates how groups use their connections with political parties and lobbying coalitions to augment their brokerage positions and enhance their influence over policy making. Evidence is drawn from statistical analysis of 263 interviews with health policy elites and a qualitative case study of the debate over the Medicare Prescription Drug, Improvement, and Modernization Act of 2003. The results explain, in part, how interest groups play their brokerage roles as dispersed actors in a decentralized system, rather than as central mediators that intervene in a wide range of policy disputes.

  15. Influence of membrane composition on its flexibility

    Energy Technology Data Exchange (ETDEWEB)

    Gerbelli, B.B.; Teixeira da Silva, E.R.; Oliveira, C.L.P.; Oliveira, E.A. [Universidade de Sao Paulo (USP), SP (Brazil)

    2012-07-01

    Full text: Lamellar phases and vesicles composed of lipids have been used as model systems to investigate biological process related to cell membrane as well as promising carriers for drugs and gene therapy. The composition of the membrane determines its three dimensional shape and its properties such as rigidity and compressibility which play an important role on membrane fusion, protein adhesion, interactions between proteins, etc. We present systematic study of a lamellar system composed mainly of lecithin which is a biocompatible phospholipid and simusol, which is a mixture of fatty acids that acts as a cosurfactant introducing flexibility to the membrane. Using X ray scattering we determine the lamellar periodicity as a function of the hydration for different formulations of the membrane; ranging from 100 % to 50 % mass fraction of lecithin. The X-ray spectra are fitted using a 4 Gaussian model [1]that allows us to determine the lamellar periodicity and the Caille parameter [2]. The ideal swelling law relating the membrane volume fraction ({phi}{sub m}) to the lamellar periodicity (D) is given by {phi}{sub m} ={delta}{sub m}/D, where {delta}{sub m} is the thickness membrane, however, when steric interactions are dominant with respect to electrostatic and van der Waals interactions, deviations from this behavior are expected [3]. We present experimental data illustrating the swelling behavior for the membrane compositions and the respective behavior of the hydration limit, membrane Luzzati [4], of the Caille parameter and qualitative interpretation of the interaction forces the systems studying the parameter membrane square amplitude fluctuation[5]. [1] Private communication with Prof. Dr. Cristiano Luis Pinto de Oliveira. [2] Caille A. et all, Acad. Sci. Paris B274 (1972) 891. [3] E. Kurtisovski et all, PRL 98, 258103 (2007). [4] Nagle et all, Curr Opin Struct Biol. 2000 Aug;10(4):474-80. [5] H. I. Petrache. Structure and interactions of fluid phospholipids

  16. Influence of a peracetic acid-based immersion on indirect composite resin.

    Science.gov (United States)

    Samuel, Susana Maria Werner; Fracaro, Gisele Baggio; Collares, Fabrício Mezzomo; Leitune, Vicente Castelo Branco; Campregher, Ulisses Bastos

    2011-06-01

    The aim of this study was to evaluate the influence of immersion in a 0.2% peracetic acid-based disinfectant on the three-point flexural strength, water sorption and water solubility of an indirect composite resin. Specimens were produced according to ISO 4049:2000 specifications and were divided in two groups: Control group, with no disinfection and Disinfected group, with three 10 min immersions in the peracetic acid intercalated with 10 min immersions in sterile distilled water. All evaluations were conducted in compliance with ISO specifications. Three-point flexural strength, water sorption and solubility of indirect composite resin before and after immersion showed no statistical significant differences (p > 0.05) and met ISO standard requirements. Immersion in peracetic acid solution showed no influence in indirect composite resin tested properties.

  17. Matrix intensification alters avian functional group composition in adjacent rainforest fragments.

    Directory of Open Access Journals (Sweden)

    Justus P Deikumah

    Full Text Available Conversion of farmland land-use matrices to surface mining is an increasing threat to the habitat quality of forest remnants and their constituent biota, with consequences for ecosystem functionality. We evaluated the effects of matrix type on bird community composition and the abundance and evenness within avian functional groups in south-west Ghana. We hypothesized that surface mining near remnants may result in a shift in functional composition of avifaunal communities, potentially disrupting ecological processes within tropical forest ecosystems. Matrix intensification and proximity to the remnant edge strongly influenced the abundance of members of several functional guilds. Obligate frugivores, strict terrestrial insectivores, lower and upper strata birds, and insect gleaners were most negatively affected by adjacent mining matrices, suggesting certain ecosystem processes such as seed dispersal may be disrupted by landscape change in this region. Evenness of these functional guilds was also lower in remnants adjacent to surface mining, regardless of the distance from remnant edge, with the exception of strict terrestrial insectivores. These shifts suggest matrix intensification can influence avian functional group composition and related ecosystem-level processes in adjacent forest remnants. The management of matrix habitat quality near and within mine concessions is important for improving efforts to preserveavian biodiversity in landscapes undergoing intensification such as through increased surface mining.

  18. Influence of fluoride in poly(d,l-lactide)/apatite composites on bone formation

    NARCIS (Netherlands)

    Luo, Xiaoman; Barbieri, D.; Passanisi, G.; Yuan, Huipin; de Bruijn, Joost Dick

    2015-01-01

    The influence of fluoride in poly(d,l-lactide)/apatite composites on ectopic bone formation was evaluated in sheep. Nano-apatite powders with different replacement levels of OH groups by fluoride (F) (0% (F0), 50% (F50), 100% (F100), and excessive (F200)) were co-extruded with poly (d,l-lactide) at

  19. Influence of curing time, overlay material and thickness on three light-curing composites used for luting indirect composite restorations.

    Science.gov (United States)

    D'Arcangelo, Camillo; De Angelis, Francesco; Vadini, Mirco; Carluccio, Fabio; Vitalone, Laura Merla; D'Amario, Maurizio

    2012-08-01

    To assess the microhardness of three resin composites employed in the adhesive luting of indirect composite restorations and examine the influence of the overlay material and thickness as well as the curing time on polymerization rate. Three commercially available resin composites were selected: Enamel Plus HRI (Micerium) (ENA), Saremco ELS (Saremco Dental) (SAR), Esthet-X HD (Dentsply/DeTrey) (EST-X). Post-polymerized cylinders of 6 different thicknesses were produced and used as overlays: 2 mm, 3 mm, 3.5 mm, 4 mm, 5 mm, and 6 mm. Two-mm-thick disks were produced and employed as underlays. A standardized amount of composite paste was placed between the underlay and the overlay surfaces which were maintained at a fixed distance of 0.5 mm. Light curing of the luting composite layer was performed through the overlays for 40, 80, or 120 s. For each specimen, the composite to be cured, the cured overlay, and the underlay were made out of the same batch of resin composite. All specimens were assigned to three experimental groups on the basis of the resin composite used, and to subgroups on the basis of the overlay thickness and the curing time, resulting in 54 experimental subgroups (n = 5). Forty-five additional specimens, 15 for each material under investigation, were produced and subjected to 40, 80, or 120 s of light curing using a microscope glass as an overlay; they were assigned to 9 control subgroups (n = 5). Three Vicker's hardness (VH) indentations were performed on each specimen. Means and standard deviations were calculated. Data were statistically analyzed using 3-way ANOVA. Within the same material, VH values lower than 55% of control were not considered acceptable. The used material, the overlay thickness, and the curing time significantly influenced VH values. In the ENA group, acceptable hardness values were achieved with 3.5-mm or thinner overlays after 120 or 80 s curing time (VH 41.75 and 39.32, respectively), and with 2-mm overlays after 40 s (VH 54

  20. Influence of increment thickness on dentin bond strength and light transmission of composite base materials.

    Science.gov (United States)

    Omran, Tarek A; Garoushi, Sufyan; Abdulmajeed, Aous A; Lassila, Lippo V; Vallittu, Pekka K

    2017-06-01

    Bulk-fill resin composites (BFCs) are gaining popularity in restorative dentistry due to the reduced chair time and ease of application. This study aimed to evaluate the influence of increment thickness on dentin bond strength and light transmission of different BFCs and a new discontinuous fiber-reinforced composite. One hundred eighty extracted sound human molars were prepared for a shear bond strength (SBS) test. The teeth were divided into four groups (n = 45) according to the resin composite used: regular particulate filler resin composite: (1) G-ænial Anterior [GA] (control); bulk-fill resin composites: (2) Tetric EvoCeram Bulk Fill [TEBF] and (3) SDR; and discontinuous fiber-reinforced composite: (4) everX Posterior [EXP]. Each group was subdivided according to increment thickness (2, 4, and 6 mm). The irradiance power through the material of all groups/subgroups was quantified (MARC® Resin Calibrator; BlueLight Analytics Inc.). Data were analyzed using two-way ANOVA followed by Tukey's post hoc test. SBS and light irradiance decreased as the increment's height increased (p composite used. EXP presented the highest SBS in 2- and 4-mm-thick increments when compared to other composites, although the differences were not statistically significant (p > 0.05). Light irradiance mean values arranged in descending order were (p composites. Discontinuous fiber-reinforced composite showed the highest value of curing light transmission, which was also seen in improved bonding strength to the underlying dentin surface. Discontinuous fiber-reinforced composite can be applied safely in bulks of 4-mm increments same as other bulk-fill composites, although, in 2-mm thickness, the investigated composites showed better performance.

  1. Young Children's Motor Interference Is Influenced by Novel Group Membership.

    Science.gov (United States)

    van Schaik, Johanna E; Endedijk, Hinke M; Stapel, Janny C; Hunnius, Sabine

    2016-01-01

    From early childhood onward, individuals use behavior copying to communicate liking and belonging. This non-verbal signal of affiliation is especially relevant in the context of social groups and indeed both children and adults copy in-group more than out-group members. Given the societal importance of inter-group interactions, it is imperative to understand the mechanistic level at which group modulations of copying occur early in development. The current study was designed to investigate the effect of novel group membership on young children's motor behavior during a simultaneous movement-observation and -execution task. Four- to six-year-olds (n = 65) first gained membership to one of two novel groups based on their color preference and put on a vest in their chosen color. Subsequently, they were instructed to draw a straight line back-and-forth on a tablet computer that was concurrently displaying a stimulus video in which a model moved her arm congruently or incongruently to the child's instructed direction. In half of the stimulus videos the model belonged to the in-group, while in the other half the model belonged to the out-group, as identified by the color of her dress. The deviations into the uninstructed direction of the children's drawings were quantified as a measure of how much observing the models' behaviors interfered with executing their own behaviors. The motor interference effect, namely higher deviations in the incongruent trials than in the congruent trials, was found only for the out-group condition. An additional manipulation of whether the models' arms followed a biological or non-biological velocity profile had little effect on children's motor interference. The results are interpreted in the context of the explicit coordinative nature of the task as an effect of heightened attention toward interacting with an out-group member. This study demonstrates that already during early childhood, novel group membership dynamically influences

  2. Influence of Temperature on Symbiotic Bacterium Composition in Successive Generations of Egg Parasitoid, Anagrus nilaparvatae

    Directory of Open Access Journals (Sweden)

    Wang Xin

    2016-07-01

    Full Text Available Anagrus nilaparvatae is the dominant egg parasitoid of rice planthoppers and plays an important role in biological control. Symbiotic bacteria can significantly influence the development, survival, reproduction and population differentiation of their hosts. To study the influence of temperature on symbiotic bacterial composition in the successive generations of A. nilaparvatae, A. nilaparvatae were raised under different constant temperatures of 22 °C, 25 °C, 28 °C, 31 °C and 34 °C. Polymerase chain reaction-denaturing gradient gel electrophoresis was used to investigate the diversity of symbiotic bacteria. Our results revealed that the endophytic bacteria of A. nilaparvatae were Pantoea sp., Pseudomonas sp. and some uncultured bacteria. The bacterial community composition in A. nilaparvatae significantly varied among different temperatures and generations, which might be partially caused by temperature, feeding behavior and the physical changes of hosts. However, the analysis of wsp gene showed that the Wolbachia in A. nilaparvatae belonged to group A, sub-group Mors and sub-group Dro. Sub-group Mors was absolutely dominant, and this Wolbachia composition remained stable in different temperatures and generations, except for the 3rd generation under 34 °C during which sub-group Dro became the dominant Wolbachia. The above results suggest that the continuous high temperature of 34 °C can influence the Wolbachia community composition in A. nilaparvatae.

  3. The influence of compositional and structural diversity on forest productivity

    Science.gov (United States)

    James N. Long; John D. Shaw

    2010-01-01

    Data from ~1500 ponderosa pine (Pinus ponderosa C. Lawson) stands in the western United States were used to examine the potential influence of compositional and structural diversity on forest productivity. Relative density, height and site quality were combined in a conceptually sound expression of the relationship between growth and growing stock for ponderosa pine-...

  4. Learning science in small multi-age groups: the role of age composition

    Science.gov (United States)

    Kallery, Maria; Loupidou, Thomais

    2016-06-01

    The present study examines how the overall cognitive achievements in science of the younger children in a class where the students work in small multi-age groups are influenced by the number of older children in the groups. The context of the study was early-years education. The study has two parts: The first part involved classes attended by pre-primary children aged 4-6. The second part included one primary class attended by students aged 6-8 in addition to the pre-primary classes. Students were involved in inquiry-based science activities. Two sources of data were used: Lesson recordings and children's assessments. The data from both sources were separately analyzed and the findings plotted. The resulting graphs indicate a linear relationship between the overall performance of the younger children in a class and the number of older ones participating in the groups in each class. It seems that the age composition of the groups can significantly affect the overall cognitive achievements of the younger children and preferentially determines the time within which this factor reaches its maximum value. The findings can be utilized in deciding the age composition of small groups in a class with the aim of facilitating the younger children's learning in science.

  5. Influence of Track Parameters on Welded Turnout Group

    Institute of Scientific and Technical Information of China (English)

    XU Qing-yuan; WANG Ping; QU Xiao-hui; LI Shu-de

    2007-01-01

    By building the finite element model, the track parameters, including the ultimate longitudinal resistance, the length of the intermediate straight line, and the gap between spacer blocks, were analyzed for their influences on the longitudinal forces and displacements of the single turnout and turnout group, respectively. The results indicate that when the longitudinal resistance drops from 32 to 20 N/cm, the maximum additional longitudinal force of the turnout group increases by 19. 2%, and the maximum additional longitudinal displacement of the turnout group grows by 85.3% compared with 50.4% for the single turnout. When the length of intermediate straight line rises from 0 m to infinite, the maximum additional longitudinal force decreases by 38.8%, and the maximum additional longitudinal displacement by 80.3%.

  6. Influences on and measures of unintentional group synchrony

    Directory of Open Access Journals (Sweden)

    Melissa Ellamil

    2016-11-01

    Full Text Available Many instances of large-scale coordination occur in real-life social situations without the explicit awareness of the individuals involved. While the majority of research to date has examined dyadic interactions – those between two individuals – during intentional or deliberate coordination, the present review surveys the handful of recent studies investigating behavioral and physiological synchrony across groups of more than two people when coordination was not an explicit goal. Both minimal (e.g., visual information, shared location and naturalistic (e.g., choir singing part, family relationship group interactions appear to promote unintentional group synchrony although they have so far only been studied separately. State differences in unintentional group synchrony, or the relative presence of coordination in various conditions, have tended to be assessed differently, such as using correlation-type relationships, compared to its temporal dynamics, or changes over time in the degree of coordination, which appear to be best captured using phase differences. Simultaneously evaluating behavioral, physiological, and social responses as well systematically comparing different synchrony measures could further our understanding of the influences on and measures of group synchrony, allowing us to move away from studying individual persons responding to static laboratory stimuli and towards investigating collective experiences in natural, dynamic social interactions.

  7. Moderating Effects of Group Status, Cohesion, and Ethnic Composition on Socialization of Aggression in Children's Peer Groups

    Science.gov (United States)

    Shi, Bing; Xie, Hongling

    2014-01-01

    We explored the effects of 3 group features (i.e., status, cohesion, and ethnic composition) on socialization processes of aggression in early adolescents' natural peer social groups. Gender differences in these effects were also determined. A total of 245 seventh-grade individuals belonging to 65 peer groups were included in the analyses. All 3…

  8. Moderating Effects of Group Status, Cohesion, and Ethnic Composition on Socialization of Aggression in Children's Peer Groups

    Science.gov (United States)

    Shi, Bing; Xie, Hongling

    2014-01-01

    We explored the effects of 3 group features (i.e., status, cohesion, and ethnic composition) on socialization processes of aggression in early adolescents' natural peer social groups. Gender differences in these effects were also determined. A total of 245 seventh-grade individuals belonging to 65 peer groups were included in the analyses.…

  9. Influences of Task Type on Interaction under Group Work Setting

    Institute of Scientific and Technical Information of China (English)

    刘晓萍

    2005-01-01

    Interaction between learners under group work setting is considered to be signifieantly influenced by task types. The present empirical study was designed to explore interaction characteristics under convergent tasks and divergent tasks from three aspects: language production, meaning negotiation and attention to form while performing different types of tasks. The results reveal that there was significant statistical difference in the total language production between two types of tasks. In terms of the occurrence of meaning negotiation and the extent to which students paid attention to language form, there were no significant difference between the two task types.

  10. [Influence Factors on Monomer Conversion of Dental Composite Resin].

    Science.gov (United States)

    Wang, Shuang; Gao, Yan; Wang, Jing; Zhang, Yan; Zhang, Yuntao; Wang, Fanghui; Wang, Qingshan

    2015-04-01

    Dental composite resin is a kind of material which has been widely used in dental restoration. Research has found that the influence of residual monomer on the material mechanical, chemical and biological properties cannot be ignored. This paper elaborates these harms of residual monomers. The effects of resin matrix, inorganic filler and initiating system, illumination, secondarily treatment on the degree of conversion were also analyzed. The paper also discusses the effective measures to increase the conversion, and offers theoretical basis for the clinical application and development of composite resin.

  11. Satisfaction with Online Commercial Group Chat: The Influence of Perceived Technology Attributes, Chat Group Characteristics, and Advisor Communication Style

    NARCIS (Netherlands)

    van Dolen, W.M.; Dabholkar, P.A.; de Ruyter, J.C.

    2007-01-01

    This study examines online commercial group chat from a structuration theory perspective. The findings support the influence of perceived technology attributes (control, enjoyment, reliability, speed, and ease of use) and chat group characteristics (group involvement, similarity, and receptivity) on

  12. The influence of a packable resin composite, conventional resin composite and amalgam on molar cuspal stiffness.

    Science.gov (United States)

    Molinaro, J D; Diefenderfer, K E; Strother, J M

    2002-01-01

    Packable resin composites may offer improved properties and clinical performance over conventional resin composites or dental amalgam. This in vitro study examined the cuspal stiffness of molars restored with a packable resin composite, a conventional posterior microfilled resin composite and amalgam. Forty-eight intact caries-free human third molars were distributed into four treatment groups (n=12) so that the mean cross-sectional areas of all groups were equal. Standardized MOD cavity preparations were made and specimens restored using one of four restorative materials: (1) a spherical particle amalgam (Tytin); (2) Tytin amalgam with a dentin adhesive liner (OptiBond Solo); (3) a conventional microfilled posterior resin composite (Heliomolar); (4) a packable posterior resin composite (Prodigy Posterior). Cuspal stiffness was measured using a Bionix 200 biomaterials testing machine (MTS). Specimens were loaded vertically to 300 N at a crosshead speed of 1.0 mm/minute. Stiffness was measured at 10 intervals: (1) prior to cavity preparation (intact); (2) following cavity preparation, but before restoration; (3) seven days after restoration; then (4) 1, 2, 3, 4, 5, 6 and 12 months after restoration. All specimens were stored at 37 degrees C in deionized water throughout the study and thermocycled (5 degrees/55 degrees C; 2000 cycles) monthly for 12 months. Repeated Measures ANOVA revealed significant differences among treatment groups over time (presin composite increased cuspal stiffness over that of amalgam.

  13. Factors influencing the aroma composition of Chardonnay wines.

    Science.gov (United States)

    Gambetta, Joanna M; Bastian, Susan E P; Cozzolino, Daniel; Jeffery, David W

    2014-07-16

    Chardonnay is one of the oldest and most widely distributed wine grape cultivars and is of commercial importance for the world's wine-producing nations. It is an extremely flexible variety that has adapted to different regions with varied weather and soil characteristics. Somewhat uniquely among white wines, Chardonnay lends itself to a wide variety of production styles, which can be tailored to the target market. Techniques such as skin maceration, barrel and stainless steel fermentation, use of selected or indigenous yeasts, malolactic fermentation, and aging in barrels with or without lees are all applicable and lead to different compositional outcomes. A number of research papers have been published with a view to understanding Chardonnay composition and quality as well as the impact of different enological techniques on the final product. This review summarizes current knowledge, explaining the influence of viticultural and production techniques on aroma composition, and poses directions for further research into Chardonnay wines.

  14. Influence of orlistat on bone turnover and body composition

    DEFF Research Database (Denmark)

    Gotfredsen, A; Westergren Hendel, H; Andersen, T

    2001-01-01

    OBJECTIVE: To investigate the influence of the pancreas lipase inhibitor orlistat (OLS) on calcium metabolism, bone turnover, bone mass, bone density and body composition when given for obesity as adjuvant to an energy- and fat-restricted diet. DESIGN: Randomized controlled double-blinded trial...... of treatment with OLS 120 mg three times daily or placebo for 1 y. SUBJECTS: Thirty obese subjects with a mean body mass index (BMI) of 36.9+/-3.7 kg/m(2) and a mean age of 41+/-11 y. Sixteen patients were assigned to OLS and 14 to placebo. MEASUREMENTS: Dual energy X-ray absorptiometry (DXA) measurements...... of bone mineral and body composition included total bone mineral content (TBMC), total bone mineral density (TBMD), lumbar spine BMC and BMD, forearm BMC and BMD, fat mass (FM), fat free-mass (FFM), percentage fat mass (FM%) as well as a DXA estimate of the body weight. Body composition (FM, FFM and FM...

  15. Personality composition alters the transmission of cuticular bacteria in social groups.

    Science.gov (United States)

    Keiser, Carl N; Howell, Kimberly A; Pinter-Wollman, Noa; Pruitt, Jonathan N

    2016-07-01

    The initial stages of a disease outbreak can determine the magnitude of the ensuing epidemic. Though rarely tested in unison, two factors with important consequences for the transmission dynamics of infectious agents are the collective traits of the susceptible population and the individual traits of the index case (i.e. 'patient zero'). Here, we test whether the personality composition of a social group can explain horizontal transmission dynamics of cuticular bacteria using the social spider Stegodyphus dumicola We exposed focal spiders of known behavioural phenotypes with a GFP-transformed cuticular bacterium (Pantoea sp.) and placed them in groups of 10 susceptible individuals (i.e. those with no experience with this bacterium). We measured bacterial transmission to groups composed of either all shy spiders, 10% bold spiders or 40% bold spiders. We found that colonies with 40% bold spiders experienced over twice the incidence of transmission compared to colonies with just 10% bold individuals after only 24 h of interaction. Colonies of all shy spiders experienced an intermediate degree of transmission. Interestingly, we did not detect an effect of the traits of the index case on transmission. These data suggest that the phenotypic composition of the susceptible population can have a greater influence on the degree of early transmission events than the traits of the index case. © 2016 The Author(s).

  16. Influence of seawater and its aerosols on copper patina composition

    Energy Technology Data Exchange (ETDEWEB)

    Veleva, L., E-mail: veleva@mda.cinvestav.mx [Applied Physics Department, Center for Investigation and Advanced Study, CINVESTAV-Merida, Carr. Ant. a Progreso, Km. 6, 97310 Merida (Mexico); Farro, W. [Department of Chemistry, Universidad Nacional de Trujillo, Av. Juan Pablo II s/n, Ciudad Universitaria, Urb. San Andres, Trujillo (Peru)

    2012-10-01

    Highlights: Black-Right-Pointing-Pointer Copper patina was grown during one-year period on samples exposed to splash, tidal, full immersion sea zone and atmospheric aerosols. Black-Right-Pointing-Pointer The cuprite and atacamite contributed most to patina formation. Black-Right-Pointing-Pointer Atacamite became the sole majority phase in the full immersion zone. Black-Right-Pointing-Pointer Cuprite decreased over time and posnjakite and chalcanthite appeared as minority phases. Black-Right-Pointing-Pointer Copper patina composition is strongly influenced by chloride pollution and specific zone conditions. - Abstract: X-ray diffraction analysis was used to monitor patina composition on copper samples exposed during one-year period to different seawater zones (splash, tidal and full immersion) and marine atmospheric aerosols. Two phases contributed most to patina formation: cuprite (copper oxide) and atacamite (copper chloride compound). Their relative XRD spectra intensities were very similar in patina formed in the tidal sea zone, but atacamite became the sole majority phase in the full immersion zone. The cuprite phase decreased over time, and two minority copper sulfates phases appeared: posnjakite and chalcanthite (CuSO{sub 4}). The results revealed that copper patina composition is strongly influenced by chloride pollution and specific zone conditions. Additional factors, such as wind-blown sand, continuous dredging in coastal areas and vessel docking, influenced degree of pollutant compound adherence to patinas and consequently their structure (porous or compact).

  17. Diet may influence the oral microbiome composition in cats.

    Science.gov (United States)

    Adler, Christina J; Malik, Richard; Browne, Gina V; Norris, Jacqueline M

    2016-06-09

    Periodontal disease is highly prevalent amongst domestic cats, causing pain, gingival bleeding, reduced food intake, loss of teeth and possibly impacts on overall systemic health. Diet has been suggested to play a role in the development of periodontal disease in cats. There is a complete lack of information about how diet (composition and texture) affects the feline oral microbiome, the composition of which may influence oral health and the development of periodontal disease. We undertook a pilot study to assess if lifelong feeding of dry extruded kibble or wet (canned and/or fresh meat combinations) diets to cats (n = 10) with variable oral health affected the microbiome. Oral microbiome composition was assessed by amplifying the V1-V3 region of the 16S gene from supragingival dental plaque DNA extracts. These amplicons were sequenced using Illumina technology. This deep sequencing revealed the feline oral microbiome to be diverse, containing 411 bacterial species from 14 phyla. We found that diet had a significant influence on the overall diversity and abundance of specific bacteria in the oral environment. Cats fed a dry diet exclusively had higher bacterial diversity in their oral microbiome than wet-food diet cats (p microbiome between cats on the two diets assessed, the relationship between these differences and gingival health was unclear. Our preliminary results indicate that further analysis of the influence of dietary constituents and texture on the feline oral microbiome is required to reveal the relationship between diet, the oral microbiome and gingival health in cats.

  18. The influence of stratification on color and appearance of resin composites.

    Science.gov (United States)

    Betrisey, Emilie; Krejci, Ivo; Di Bella, Enrico; Ardu, Stefano

    2016-05-01

    The aim of this in vitro study was to determine the influence of the order of composite layers' stratification on resin composites color and appearance when restoring an anterior composite tooth on the 3D color coordinates L*a*b* by use of a spectrophotometer. A total of 192 discs samples made of two different commercial available composite materials (Miris 2 and HRI) of enamel (E) and dentin (D) shade, each with a 1 mm thickness, were divided into 6 configurations. The superposition of 4 samples for a total of 16 specimens per group determined the investigated configurations. All groups showed significant (p stratification, measured from the buccal side and from the palatal side. Perceptible differences were detected between all groups except for E1DDE, EDDE1 and EDDD, independent of the background (white or black). The realization of the palatal layer with dentin composite shade did not change the final outcome within the limit of a total 4 mm thickness in comparison to the palatal layer with enamel composite shade.

  19. Influence of composite insertion technique on gap formation

    Directory of Open Access Journals (Sweden)

    Neha Kapoor

    2016-01-01

    Full Text Available Aim: To compare newer bulk-fill composites with an incrementally filled composite for adaptability and subsequent gap formation at the pulpal floor. Materials and Methods: Class I cavities were prepared in 60 intact molars, with a shallow depression in the center of the pulpal floor. The samples were divided into four groups (n = 15, according to the material used; smart dentine replacement (SDR, SonicFill, Ever X Flow and Z350 XT, restored to a depth of 4 mm. Following thermocycling, samples were sectioned buccolingually and examined under a stereomicroscope. Seven samples from each group were coated with nail varnish except for approximately 1 mm around the tooth restoration junction. These samples were examined under stereomicroscope after staining with 2% buffered methylene blue dye. The remaining samples were examined under a scanning electron microscope for gap formation. The data were statistically analyzed using one-way ANOVA and post-hoc Bonferroni test. Results: SDR showed the significantly best adaptability as compared to both SonicFill and Ever X Flow (comparable. However, significantly least adaptive capacity was seen in the incrementally filled group (Z350 XT. Conclusion: Bulk-fill composites performed better than incremental composites, demonstrating better adaptability and less gap formation at the pulpal floor.

  20. Influence of composition on rate of polymerization contraction of light-curing resin composites.

    Science.gov (United States)

    Asmussen, Erik; Peutzfeldt, Anne

    2002-06-01

    A slow contraction may result in reduced gap formation when a restorative resin polymerizes in a dental cavity. It was the aim in the present work to investigate the rate of contraction in relation to composition of experimental light-curing resin composites. The monomer of the resin composites consisted of mixtures of BisGMA, TEGDMA, and in one series HEMA. The resins contained varying amounts of initiators, co-initiators, and inhibitor, and were made composite by adding a silanized glass filler to a content of 74% by weight of the composite paste. The polymerization contraction up to 120 sec was determined by means of the bonded-disk method. Within the ranges studied, the concentration of initiator and co-initiator in the monomer mixture had only an insignificant influence on rate of polymerization. In comparison to camphorquinone, the initiators 1-phenyl-1,2-propanedione and benzil reduced the rate of polymerization without affecting the final contraction. In comparison to N,N-dimethyl-p-aminobenzoic acid ethyl ester, N,N-cyanoethyl methylaniline was as effective, while N,N-diethanol-p-toluidine was less effective as co-initiator. A relatively high content of the inhibitor methoxyhydroquinone reduced the initial rate but not the final polymerization contraction. The rate of polymerization increased with the level of HEMA and TEGDMA in the monomer mixture. It was concluded that intrinsic slow cure may be obtained with certain compositions of resin composites without impairing the final extent of polymerization.

  1. Influence of orlistat on bone turnover and body composition

    DEFF Research Database (Denmark)

    Gotfredsen, A; Westergren Hendel, H; Andersen, T

    2001-01-01

    of bone mineral and body composition included total bone mineral content (TBMC), total bone mineral density (TBMD), lumbar spine BMC and BMD, forearm BMC and BMD, fat mass (FM), fat free-mass (FFM), percentage fat mass (FM%) as well as a DXA estimate of the body weight. Body composition (FM, FFM and FM...... biochemical variables except s-osteocalcin changed significantly after 1 y in the OLS group, disclosing a pattern of an incipient negative vitamin D balance, a secondary increase in PTH-secretion, and an increase in bone turnover with the emphasis on an increase in resorption parameters (fU-OHpr/creat, f...

  2. Main sugar composition of floral nectar in three species groups of Scrophularia (Scrophulariaceae) with different principal pollinators.

    Science.gov (United States)

    Rodríguez-Riaño, T; Ortega-Olivencia, A; López, J; Pérez-Bote, J L; Navarro-Pérez, M L

    2014-11-01

    In some angiosperm groups, a parallelism between nectar traits and pollination syndromes has been demonstrated, whereas in others there is not such relationship and it has been explained as due to phylogenetic constraints. However, nectar trait information remains scarce for many plant groups. This paper focuses on three groups of Scrophularia species, with different flower sizes and principal pollinators, to find out whether nectar sugar composition is determined by pollinator type or reflects taxonomic affinities. Since the species we examined have protogynous flowers, and gender bias in nectar sugar composition has been noted in few plant groups, we also investigated whether sexual phase influenced Scrophularia nectar composition. The sugar composition was found to be similar in all species, having high-sucrose nectar, except for the Macaronesian Scrophularia calliantha, which was the only species with balanced nectar; this last kind of nectar could be associated with the high interaction rates observed between S. calliantha and passerine birds. The nectar sugar composition (high in sucrose) was unrelated to the principal pollinator group, and could instead be considered a conservative taxonomic trait. No gender bias was observed between functionally female and male flowers for nectar volume or concentration. However, sexual phase significantly affected sucrose percentage in the largest-flowered species, where the female phase flowers had higher sucrose percentages than the male phase flowers. © 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.

  3. Influence of Different Bonding Agents and Composite Resins on Fracture Resistance of Reattached Incisal Tooth Fragment

    Directory of Open Access Journals (Sweden)

    Davari AR.

    2014-03-01

    Full Text Available Statement of Problem: Reattachment of the fractured tooth fragment should be considered as a conservative treatment and valid alternative to a composite restoration. Purpose: This in vitro study was to evaluate the influence of different adhesives and composite resins on fracture resistance of dental fragment reattached to sectioned incisal edges. Materials and Method: 120 sound human maxillary central incisors were selected under standard conditions and randomly divided into 3 groups, 12 sound teeth were used as a control group and the remaining teeth were assigned to 3 groups (n=36 and each group into three subgroups (n=12. The incisal third of samples was sectioned using a diamond disk and the respective fragments were then reattached utilizing different intermediate restorative materials, namely: i adhesive materials alone (OptiBond S or OptiBond XTR or OptiBond All-in-One; ii Premise flowable composite and iii Point 4 composite in the one of mentioned adhesive interface. After storage for two weeks at 37°C and 100% humidity and then thermocycling; shear bond strength (SBS was recorded in kilogram force (kgf by applying a load in the middle incisal third with a Zwick Universal Testing Machine at a cross-head speed of 1 mm/min. Data was analyzed with one-way ANOVA and Tukey HSD (p< 0.05. Results: The control group had a significantly higher SBS than other groups (p= 0.001; the highest SBS values was obtained using the premise flowable composite and OptiBond S adhesive (112.44±30.46 Mpa; and the lowest with OptiBond All-in-One alone (33.97± 15.63 Mpa. Conclusion: Although, none of the tested materials provided fracture resistance similar to that found with the intact maxillary central incisors; utilizing the premise flowable composite and OptiBond S adhesive improved the SBS of the reattached fragment than other materials.

  4. Stiffness matrix determination of composite materials using lamb wave group velocity measurements

    Science.gov (United States)

    Putkis, O.; Croxford, A. J.

    2013-04-01

    The use of Lamb waves in Non-Destructive Evaluation (NDE) and Structural Health Monitoring (SHM) is gaining popularity due to their ability to travel long distances without significant attenuation, therefore offering large area inspections with a small number of sensors. The design of a Lamb-wave-based NDE/SHM system for composite materials is more complicated than for metallic materials due to the directional dependence of Lamb wave propagation characteristics such as dispersion and group velocity. Propagation parameters can be theoretically predicted from known material properties, specifically the stiffness matrix and density. However, in practice it is difficult to obtain the stiffness matrix of a particular material or structure with high accuracy, hence introducing errors in theoretical predictions and inaccuracies in the resulting propagation parameters. Measured Lamb wave phase velocities can be used to infer the stiffness matrix, but the measurements are limited to the principal directions due to the steering effect (different propagation directions of phase and corresponding group velocities). This paper proposes determination of the stiffness matrix from the measured group velocities, which can be unambiguously measured in any direction. A highly anisotropic carbon-fibre-reinforced polymer plate is chosen for the study. The influence of different stiffness matrix elements on the directional group velocity profile is investigated. Thermodynamic Simulated Annealing (TSA) is used as a tool for inverse, multi variable inference of the stiffness matrix. A good estimation is achieved for particular matrix elements.

  5. The Influence of Chemical Composition on LNG Pool Vaporization

    Directory of Open Access Journals (Sweden)

    Yu Zhidong

    2017-01-01

    Full Text Available A model is used to examine the influence of chemical composition on the vaporization rate of LNG during spreading. Calculations have been performed whereby the vaporization rate of the LNG mixtures has been compared to the vaporization of pure methane under the initial conditions. The detailed results indicate that the vaporization rate LNG mixture is different to that of pure methane. LNG as the liquid mixture gets rich in ethane and isobaric latent heat increases rapidly, leading to the rate vaporization of LNG decrease in compared to pure methane.

  6. Ripening influences banana and plantain peels composition and energy content

    OpenAIRE

    Happi Emaga, Thomas; Bindelle, Jérôme; Angeesens, Richard; Buldgen, André; Wathelet, Bernard; Paquot, Michel

    2011-01-01

    Musa sp. peels are widely used by smallholders as complementary feeds for cattle in the tropics. A study of the influence of the variety and the maturation stage of the fruit on fermentability and metabolisable energy (ME) content of the peels was performed using banana (Yangambi Km5) and plantain (Big Ebanga) peels at three stages of maturation in an in vitro model of the rumen. Peel samples were analysed for starch, free sugars and fibre composition. Samples were incubated in the presence o...

  7. Influence of composition on friction-wear behavior of composite materials reinforced by brass fibers

    Institute of Scientific and Technical Information of China (English)

    JIA Xian; LING Xiaomei

    2003-01-01

    In the study, for the composite materials reinforced by brass fibers, the influence of dominant ingredients, such as organic adhesion agent, cast iron debris, brass fiber, and graphite powder, on the friction-wear characteristics was investigated. The friction-wear experiment was carried out on the block-on-ring tribometer MM200. The worn surfaces of the friction pair consisting of the composite materials and grey cast iron HT200 under dry sliding friction were examined using scanning electron microscope (SEM), energy dispersive analysis (EDX) and differential thermal analysis-thermogravimetric analysis (DTA-TAG). The experimental results showed that the friction coefficient and the wear loss of the composite material increase obviously with the increase of cast iron debris content, but decrease obviously with the increase of graphite powder content, and increase a little when the mass fraction of brass fiber was over 19%, and the orientation of brass fiber has obvious influence on friction-wear property. When the mass fraction of organic adhesion agent was about 10-11%, the composite materials have an excellent friction-wear performance. The friction heat can pyrolyze organic ingredient in worn surface layer.

  8. Influence of nuclear glasses composition on their liability to deterioration; Influence de la composition des verres nucleaires sur leur alterabilite

    Energy Technology Data Exchange (ETDEWEB)

    Tovena, I.

    1995-09-29

    This contributes to the study of the nuclear glasses composition influence on their liability to deterioration. The methodology of the experimental research used has lead to define between the thirty oxides which form the reference glass light water, six oxides of interest. For each of these oxides, a composition variation area has been defined. A matrix of twenty glass compositions has then been defined. The preparation of materials of these compositions has sometimes lead to materials weakly heterogeneous which have been characterized before deterioration. This study has been completed by those of three glasses in a composition variation area narrower of the light water nuclear glass : the R7T7 and two glasses at limits having respectively an initial dissolution velocity at 100 degrees Celsius theoretically maximum and minimum. Some deterioration parameters in pure water have been experimentally measured on the twenty three glasses : 1) an initial dissolution velocity at 100 degrees (Vo{sub 1}00) Celsius and another one at 90 degrees Celsius (Vo{sub 9}0) 2) a dissolution velocity in conditions near the saturation at 90 degrees Celsius 3) an apparent solubility of glass based on the ortho silicic acid activity 4) the evolution of the dissolution kinetics at 90 degrees Celsius in sub-saturated medium towards saturated medium 5) the alteration films nature developed at the glasses surface during these last alteration tests. Some thermodynamic and structural models have been studied in order to predict Vo{sub 9}0 and Vo{sub 1}00. The dissolution kinetic law developed from reference glass dissolution results has been studied with the calculation code LIXIVER. It has not been able to be used for most of the glasses compositions studied. As a consequence, the glasses dissolution control by a surface reaction which are itself controlled by the only dissolved silica is an hypothesis which is not verified for the greater part of the glasses. (O.L.). refs., figs., tabs.

  9. The influence of maternal body composition on birth weight.

    LENUS (Irish Health Repository)

    Farah, Nadine

    2012-02-01

    OBJECTIVE: To identify the maternal body composition parameters that independently influence birth weight. STUDY DESIGN: A longitudinal prospective observational study in a large university teaching hospital. One hundred and eighty-four non-diabetic caucasian women with a singleton pregnancy were studied. In early pregnancy maternal weight and height were measured digitally in a standardised way and the body mass index (BMI) was calculated. At 28 and 37 weeks\\' gestation maternal body composition was assessed using segmental multifrequency bioelectrical impedance analysis. At delivery the baby was weighed and the clinical details were recorded. RESULTS: Of the women studied, 29.2% were overweight and 34.8% were obese. Birth weight did not correlate with maternal weight or BMI in early pregnancy. Birth weight correlated with gestational weight gain (GWG) before the third trimester (r=0.163, p=0.027), but not with GWG in the third trimester. Birth weight correlated with maternal fat-free mass, and not fat mass at 28 and 37 weeks gestation. Birth weight did not correlate with increases in maternal fat and fat-free masses between 28 and 37 weeks. CONCLUSIONS: Contrary to previous reports, we found that early pregnancy maternal BMI in a non-diabetic population does not influence birth weight. Interestingly, it was the GWG before the third trimester and not the GWG in the third trimester that influenced birth weight. Our findings have implications for the design of future intervention studies aimed at optimising gestational weight gain and birth weight. CONDENSATION: Maternal fat-free mass and gestational weight gain both influence birth weight.

  10. The influence of maternal education in a group of woman

    Directory of Open Access Journals (Sweden)

    Lourdes Ortiz Villanueva

    2013-03-01

    Full Text Available Understanding that pregnancy and childbirth are physiological situations of women, we can wonder us what brings maternal education (ME. Recent studies have no conclusive findings about its effectiveness. When historically ME began, the focus was on reducing pain and improving child-bearing. However, the change in the way of life of women and the introduction of new strategies in the care of child-bearing, as non-intervention, epidurals and birth plan, among others, forces us to review the objectives and activity.Objective: Analyze why women come to the courses of ME (maternal education and how it influences them.Method: We analyze a real context in which we work and research about the experiences of pregnant women, developing a qualitative research using "discourse analysis" of information generated from the open interviews to women attending an ME program in a Health Center in Madrid (Spain. All interviews will be recorded with audio system. The participants in this research will be selected from a group of Spanish-speaking women closer in their child-bearing date.

  11. Influence of fluoride in poly(d,l-lactide)/apatite composites on bone formation.

    Science.gov (United States)

    Luo, X; Barbieri, D; Passanisi, G; Yuan, H; de Bruijn, J D

    2015-05-01

    The influence of fluoride in poly(d,l-lactide)/apatite composites on ectopic bone formation was evaluated in sheep. Nano-apatite powders with different replacement levels of OH groups by fluoride (F) (0% (F0), 50% (F50), 100% (F100), and excessive (F200)) were co-extruded with poly (d,l-lactide) at a weight ratio of 1:1. Fluoride release from the composites (CF0, CF50, CF100, and CF200) was evaluated in vitro and bone formation was assessed after intramuscular implantation in sheep. After 24 weeks in simulated physiological solution, CF0 and CF50 showed negligible fluoride release, whereas it was considerable from the CF100 and CF200 composites. Histology showed that the incidence of de novo bone formation decreased in implants with increasing fluoride content indicating a negative influence of fluoride on ectopic bone formation. Furthermore, a significant decrease in resorption of the high fluoride-content composites and a reduction in the number of multinucleated giant cells were seen. These results show that instead of promoting, the presence of fluoride in poly(d,l-lactide)/apatite composites seemed to suppresses their resorption and osteoinductive potential in non-osseous sites. © 2014 Wiley Periodicals, Inc.

  12. Compositional and dimensional factors influencing pork belly firmness.

    Science.gov (United States)

    Soladoye, O P; Uttaro, B; Zawadski, S; Dugan, M E R; Gariépy, C; Aalhus, J L; Shand, P; Juárez, M

    2017-07-01

    We explored various dimensional and compositional factors that can influence the perception of pork belly firmness. Bellies from 198 pigs of three different genotypes, two sexes, two slaughter weights and three different diets were recovered and belly firmness was assessed using the belly-flop angle and a 5-point scale subjective measurement. Dimensional and compositional factors were recorded on intact and sheet-ribbed bellies. Subjective belly score was negatively correlated with belly-flop angle (r=-0.89). Regression analysis accounted for 77 and 83% of the variability in subjective belly firmness and belly-flop angle measurement, respectively. Belly length, weight and width influenced both measures of belly firmness, but these effects were more important for the belly-flop angle. After correcting flop angle using belly length, the effect of belly weight disappeared and the effect of other traits was more like those observed for subjective scoring. Hence, undue effect of belly length should be corrected for if this set-up is to be implemented in commercial plants. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  13. Influence of working parameters on the composite electrodeposition

    Science.gov (United States)

    Pasare, M. M.

    2015-11-01

    Composite materials are extensively studied, especially in recent years, which have a wide application in industry. Among these composite materials, in this paper we studied about electrolyte composites obtained. The matrix is made up of particles of Ni-P on which have been deposited Si-C hard particles. The amount of phosphorus incorporated into the layer increases with increasing the content of phosphorous acid in the electrolyte. The content of phosphorus incorporated into the coating composition evolves as both solid as well as particle-free solutions. When the content of phosphorous acid in the electrolyte is low and where alloys are micro crystallized, the presence of particulates changes a little the phosphorus content. At the increase of phosphorus content included in the coating is observed that the incorporation of phosphorus is higher for increasing the amount of silicon carbide particles. This matrix study was done according to the amount of phosphorus in the deposited layer. The co-deposited phosphorus modifies the crystallization mechanism so the super saturation nickel network by phosphorus allows the inhibition of the growth of nickel crystallites whose size decreases until the complete amorphization of the solid solution. The development of these deposits was aimed at determining the influence of the variation of phosphorous acid in the electrolyte, and therefore the change in the content of phosphorus included in the layer for the SiC particulate, on the one hand, and, on the other hand, it was intended the influence of heat treatment on the deposition hardness. After the measurements, it is noted that the layer thicknesses are higher for the deposition obtained from electrolyte with small containing of phosphorous acid. The structure of the Ni-P alloy and the composite material Ni-P / SiC, depends on the amount of phosphorus contained in the layer and varies from the crystalline state (the low content of phosphorus) to the amorphous state (the

  14. Gender, Group Composition, and Task Type in Small Task Groups Using Computer-Mediated Communication.

    Science.gov (United States)

    Savicki, Victor; And Others

    1996-01-01

    To investigate gender effects on computer-mediated communication, undergraduate psychology students were put in small groups (males, females, or mixed) and were assigned feminine content (decision making) and masculine content (intellective) task types. Groups of females, regardless of task, sent more words per e-mail message, were more satisfied…

  15. Influence of Material Distribution on Impact Resistance of Hybrid Composites

    Science.gov (United States)

    Abatan, Ayu; Hu, Hurang

    1998-01-01

    Impact events occur in a wide variety of circumstances. A typical example is a bullet impacting a target made of composite material. These impact events produce time-varying loads on a structure that can result in damage. As a first step to understanding the damage resistance issue in composite laminates, an accurate prediction of the transient response during an impact event is necessary. The analysis of dynamic loadings on laminated composite plates has undergone considerable development recently. Rayleigh-Ritz energy method was used to determine the impact response of laminated plates. The impact response of composite plates using shear deformation plate theory was analyzed. In recent work a closed-form solution was obtained for a rectangular plate with four edges simply supported subjected to a center impact load using classical plate theory. The problem was further investigated and the analysis results compared of both classical plate theory and shear deformation theory, and found that classical plate theory predicts very accurate results for the range of small deformations considered. In this study, the influence of cross sectional material distribution on the comparative impact responses of hybrid metal laminates subjected to low and medium velocity impacts is investigated. A simple linear model to evaluate the magnitude of the impact load is proposed first, and it establishes a relation between the impact velocity and the impact force. Then a closed-form solution for impact problem is presented. The results were compared with the finite element analysis results. For an 11 layer-hybrid laminate, the impact response as a function of material distribution in cross-section is presented. With equal areal weight, the effect of the number of laminate layers on the impact resistance is also investigated. Finally, the significance of the presented results is discussed.

  16. The influence of mouthrinses and simulated toothbrushing on the surface roughness of a nanofilled composite resin

    Directory of Open Access Journals (Sweden)

    Keico Graciela Sano Trauth

    2012-06-01

    Full Text Available The aim of this study was to determine the influence of mouthrinses on the surface roughness of a nanofilled composite resin after toothbrushing. One hundred nanofilled composite resin specimens were prepared and randomly distributed into two groups-brushed and non-brushed-and then assigned to five subgroups, according to the mouthrinse solutions (n = 10: Colgate Plax Fresh Mint, Oral B, Cepacol, Colgate Plax, and artificial saliva. Each sample was immersed in 20 mL of the mouthrinses for 1 minute, 5 days per week, twice a day, for a 3-week period. The control group used in the study was one in which the specimens were not subjected to brushing and remained only in artificial saliva. Toothbrushing was performed once a week for 1 minute, for 3 weeks. Surface roughness measurements (Ra were performed after the immersion period and toothbrushing, by means of a profilometer. Data were analyzed by two-way ANOVA and Tukey's test. Analysis revealed that the association between toothbrushing and Colgate Plax Fresh Mint produced the lowest surface roughness (p < 0.05. All other groups tested (Oral B, Cepacol, Colgate Plax, artificial saliva exhibited no statistically significant differences between surfaces, whether subjected to toothbrushing or not (p < 0.05. It was concluded that the surface roughness of the nanofilled composite resin tested can be influenced by the mouthrinse associated with toothbrushing.

  17. Changing the composition of the group hydrocarbons of diesel fractions in the process of hydrotreating

    Science.gov (United States)

    Krivtcova, N.; Baklashkina, К; Sabiev, Sh; Krivtsov, E.; Syskina, A.

    2016-09-01

    Change in group composition of sulfur compounds and structural group composition of the diesel fractions in the course of hydrotreating is presented in the paper. The removal degree of sulfur compounds is shown to comprise 95.8% rel. The homologs of benzothiophenes are removed for 93.9% rel., ones of the dibenzothiophenes are for 90.7% rel. A considerable change in group composition of diesel fraction is established in the course of hydrotreating. Hydrogenation degree of aromatic hydrocarbons is 24.4% wt., the amount of saturated hydrocarbons has increased by 20.4% wt.

  18. Soft Drink Influence on Margin Integrity in Composite Resin Restorations

    OpenAIRE

    Lafuente DDS, MS, Jose; Abad DDS, Karol

    2015-01-01

    The purpose of this study was to evaluate the effect that certain previously selected soda drinks could have on the integrity of the margins of composite restorations made on 25 human teeth, where the margins were placed both on enamel and dentin. Specimens were divided in different groups (n=5) to be exposed to soft drinks 30 minutes a day for 30 days. Selected drinks were: Coca Cola, Coca Cola Zero, Squirt, Gladiator and water. SEM pictures were taken at the beginning and at the 30 day mark...

  19. Short Circuits or Superconductors? Effects of Group Composition on High-Achieving Students' Science Assessment Performance.

    Science.gov (United States)

    Webb, Noreen M.; Nemer, Kariane Mari; Zuniga, Stephen

    2002-01-01

    Studied the effects of group ability composition (homogeneous versus heterogeneous) on group processes and outcomes for high-ability students completing science assessments. Results for 83 high ability students show the quality of group functioning serves as the strongest predictor of high-ability students' performance and explained much of the…

  20. Believing shapes seeing: The impact of diversity beliefs on the construal of group composition.

    NARCIS (Netherlands)

    A.C. Homan; L.L. Greer; K.A. Jehn; L. Koning

    2010-01-01

    Previous research has suggested that diversity effects depend on how group members perceive their group’s composition. However, what determines how diversity is perceived is unclear. We argue that the way in which group members construe their group’s diversity is shaped by group members’ beliefs abo

  1. The Influence of Composite Thickness with or without Fibers on Fracture Resistance of Direct Restorations in Endodontically Treated Teeth

    OpenAIRE

    Torabzadeh, Hassan; Ghassemi, Amir; Sanei, Masoud; Razmavar, Sara; Sheikh-Al-Eslamian, Seyedeh Mahsa

    2014-01-01

    Introduction: This in vitro study evaluated the influence of composite thickness (with or without fiber reinforcement) on fracture resistance of direct restorations in endodontically treated teeth. Methods and Materials: Fifty-six intact human premolars were chosen and randomly divided into four groups (n=14). After preparation of a mesio-occluso-distal (MOD) cavities and cusp reduction, the teeth were endodontically treated. Subsequently, the samples were restored with composite resin using ...

  2. Influence of Reversibly Associating Side Group Bond Strength on Viscoelastic Properties of Polymer Melts

    Science.gov (United States)

    Lewis, Christopher; Stewart, Kathleen; Anthamatten, Mitchell

    2013-03-01

    Reversible hydrogen-bonding between side-groups of linear polymers can sharply influence a material's dynamic mechanical behavior, giving rise to valuable shape memory and self-healing properties. Here, we investigate how bond-strength affects the bulk rheological behavior of functional poly(n-butyl acrylate) (PBA) melts. A series of random copolymers containing three different reversibly bonding groups (aminopyridine, carboxylic acid, and ureidopyrimidinone) were synthesized to systematically vary the side-group hydrogen bond strength (~26, 40, 70 kJ/mol). The materials' volumetric hydrogen-bond energy densities can be tuned by adjusting the side-group composition. By comparing the viscoelastic behavior of materials containing an equivalent bond energy density, with different bonding groups, the efficacy and cooperativity of reversible binding can be directly examined. Melt rheology results are interpreted using a state-of-ease model that assumes continuous mechanical equilibrium between applied stress and resistive stresses of entropic origin arising from a network of reversible bonds. The authors acknowledge support from funding provided by the National Science Foundation under Grant DMR-0906627

  3. The influence of halo assembly on galaxies and galaxy groups

    CERN Document Server

    Zapata, Tatiana; Padilla, Nelson; Tissera, Patricia

    2008-01-01

    We study the variations of group galaxy properties according to their assembly history in groups identified in the SDSS-DR6 (hereafter SDSS) catalogue. Using mock SDSS group catalogues, we find that the isolation and concentration of a galaxy group are good observational discriminators of group assembly. However, analysing the mean spectral type of SDSS groups as a function of concentration and isolation, we find that while SDSS massive groups confirm the predicted correlation between concentration and age found in mock catalogues, they disagree with models in the isolation-age trend. This may be partially explained in terms of possible problems associated to the modelling of cold gas in satellite galaxies in semi-analytical models, which could be overestimating the effects of environment. We study properties of galaxies in groups of similar masses and different ages, finding important variations between model and observations. These variations can be explained in terms of the different isolation-age trends o...

  4. Implicit Contracts Regulating Small Group Leadership: The Influence of Culture.

    Science.gov (United States)

    Zamarripa, Perrin Orr; Krueger, Dorothy Lenk

    1983-01-01

    Examined culture variables in the negotiation of implicit rules which govern leadership behavior in small groups. American, French, and Arab students (N=42) were assigned identical decision-making tasks. Results showed monocultural groups presented homogeneous rules governing leadership prior to interaction, while intercultural groups presented…

  5. The Influence of Cognitive Diversity on Group Problem Solving Strategy

    Science.gov (United States)

    Lamm, Alexa J.; Shoulders, Catherine; Roberts, T. Grady; Irani, Tracy A.; Snyder, Lori J. Unruh; Brendemuhl, Joel

    2012-01-01

    Collaborative group problem solving allows students to wrestle with different interpretations and solutions brought forth by group members, enhancing both critical thinking and problem solving skills. Since problem solving in groups is a common practice in agricultural education, instructors are often put in the position of organizing student…

  6. Young children's motor interference is influenced by novel group membership

    NARCIS (Netherlands)

    Schaik, J.E. van; Endedijk, H.M.; Stapel, J.C.; Hunnius, S.

    2016-01-01

    From early childhood onward, individuals use behavior copying to communicate liking and belonging. This non-verbal signal of affiliation is especially relevant in the context of social groups and indeed both children and adults copy in-group more than out-group members. Given the societal importance

  7. Influence of mechanical load bias on converse magnetoelectric laminate composites

    Science.gov (United States)

    Wu, Tao; Emmons, Michael; Chung, Tien-Kan; Sorge, Jian; Carman, Gregory P.

    2010-05-01

    A piezofiber/Metglas (PFM) magnetoelectric (ME) laminate has been integrated into a graphite epoxy composite (GEC) to study the converse ME effect (CME). Experimental data on a PFM/GEC subjected to both a dc magnetic field bias and a dc mechanical load bias while exciting it with an ac electric driving voltage are presented. Results of these tests indicate that both the mechanical load and the dc magnetic field strongly influence the CME response. Furthermore, an optimum mechanical load exists to maximize the CME coefficient, which should also be present in standalone ME laminates. These results reveal that the CME coefficient can be further increased with a proper mechanical load bias. Therefore, the selection of an appropriate mechanical preload as well as dc magnetic bias will maximize the CME response and sensitivity in ME laminates as well as integrated structural systems.

  8. Influence of groundwater composition on subsurface iron and arsenic removal

    KAUST Repository

    Moed, David H.

    2012-06-01

    Subsurface arsenic and iron removal (SAR/SIR) is a novel technology to remove arsenic, iron and other groundwater components by using the subsoil. This research project investigated the influence of the groundwater composition on subsurface treatment. In anoxic sand column experiments, with synthetic groundwater and virgin sand, it was found that several dissolved substances in groundwater compete for adsorption sites with arsenic and iron. The presence of 0.01 mmol L -1phosphate, 0.2 mmol L -1 silicate, and 1 mmol L -1 nitrate greatly reduced the efficiency of SAR, illustrating the vulnerability of this technology in diverse geochemical settings. SIR was not as sensitive to other inorganic groundwater compounds, though iron retardation was limited by 1.2 mmol L -1 calcium and 0.06 mmol L -1 manganese. © IWA Publishing 2012.

  9. Plant functional group composition and large-scale species richness in European agricultural landscapes

    NARCIS (Netherlands)

    Liira, J.; Schmidt, T.; Aavik, T.; Arens, P.F.P.; Augenstein, I.; Bailey, D.; Billeter, R.; Bukacek, R.; Burel, F.; Blust, de G.; Cock, de R.; Dirksen, J.; Edwards, P.J.; Hamersky, R.; Herzog, F.; Klotz, S.; Kuhn, I.; Coeur, Le D.; Miklova, P.; Roubalova, M.; Schweiger, O.; Smulders, M.J.M.; Wingerden, van W.K.R.E.; Bugter, R.J.F.; Zobel, M.

    2008-01-01

    Question: Which are the plant functional groups responding most clearly to agricultural disturbances? Which are the relative roles of habitat availability, landscape configuration and agricultural land use intensity in affecting the functional composition and diversity of vascular plants in agricult

  10. Estimation of pyrethroid pesticide intake using regression modeling of food groups based on composite dietary samples

    Science.gov (United States)

    Population-based estimates of pesticide intake are needed to characterize exposure for particular demographic groups based on their dietary behaviors. Regression modeling performed on measurements of selected pesticides in composited duplicate diet samples allowed (1) estimation ...

  11. Functional Group Compositions of Carbonaceous Materials of Hayabusa-Returned Samples

    Science.gov (United States)

    Yabuta, H.; Uesugi, M.; Naraoka, H.; Ito, M.; Kilcoyne, D.; Sandford, S. A.; Kitajima, F.; Mita, H.; Takano, Y.; Yada, T.; Karouji, Y.; Ishibashi, Y.; Okada, T.; Abe, M.

    2014-09-01

    We have analyzed the functional group compositions of the carbonaceous materials of Hayabusa-returned samples by STXM-XANES, in order to identify whether the materials are terrestrial or extraterrestrial.

  12. Influence of beverage composition on the results of erosive potential measurement by different measurement techniques.

    NARCIS (Netherlands)

    Jager, D.H.; Vieira, A.M.; Ruben, J.L.; Huysmans, M.C.D.N.J.M.

    2008-01-01

    The influence of beverage composition on the measurement of erosive potential is unclear. The aim of this study was to evaluate whether beverage composition influences the measurement of erosive potential and to evaluate the influence of exposure in small and large volumes. Eleven beverages were inc

  13. Influence of beverage composition on the results of erosive potential measurement by different measurement techniques

    NARCIS (Netherlands)

    Jager, D. H. J.; Vieira, A. M.; Ruben, J. L.; Huysmans, M. C. D. N. J. M.

    2008-01-01

    The influence of beverage composition on the measurement of erosive potential is unclear. The aim of this study was to evaluate whether beverage composition influences the measurement of erosive potential and to evaluate the influence of exposure in small and large volumes. Eleven beverages were inc

  14. Influence of silane content and filler distribution on chemical-mechanical properties of resin composites

    Directory of Open Access Journals (Sweden)

    Tathy Aparecida XAVIER

    2015-01-01

    Full Text Available This study investigated the influence of silane concentration and filler size distribution on the chemical-mechanical properties of experimental composites. Experimental composites with silane contents of 0%, 1% and 3% (in relation to filler mass and composites with mixtures of barium glass particles (median size = 0.4, 1 and 2 μm and nanometric silica were prepared for silane and filler analyses, respectively. The degree of conversion (DC was analyzed by FTIR. Biaxial flexural strength (BFS was tested after 24-h or 90-d storage in water, and fracture toughness, after 24 h. The data were subjected to ANOVA and Tukey’s test (p = 0.05. The DC was not significantly affected by the silane content or filler distribution. The 0% silane group had the lowest immediate BFS, and the 90-d storage time reduced the strength of the 0% and 3% groups. BFS was not affected by filler distribution, and aging decreased the BFS of all the groups. Silanization increased the fracture toughness of both the 1% and 3% groups, similarly. Significantly higher fracture toughness was observed for mixtures with 2 μm glass particles. Based on the results, 3% silane content boosted the initial strength, but was more prone to degradation after water storage. Variations in the filler distribution did not affect BFS, but fracture toughness was significantly improved by increasing the filler size.

  15. The influence and ethics of interest groups on policy incentives for clean energy development

    Science.gov (United States)

    Maguire, Mariana C.

    The clean energy revolution in the United States is not going to happen until diverse stakeholders in the coalition of clean energy proponents strengthen their cohesion and influence—two critical tools for interest group's to be successful in driving the formulation of public policy. Currently, clean energy technology and resource development is supported by a highly diverse coalition of interest groups such as environmental groups, health organizations, industry, and the Defense Department, whose primary goals are often unrelated. Yet their objectives are increasingly well served by pursuing clean energy development by pushing lawmakers for supportive policies. However, characteristics of this ad hoc coalition can hinder its influence and cohesion. Whereas, fossil fuel interests—exemplified by the coalition of oil proponents—are highly cohesive and influential. This thesis will analyze whether there is a correlation between public policies on clean energy, and the strength of interest group influence over those policy decisions. It will begin with an analysis of interest group theories. Next it will analyze the histories of the oil industry as the model opponent of clean energy policies, and the biofuels, wind energy, and solar energy industries as the model proponents of clean energy policies. The composition of the respective coalitions will reveal if they are diverse or similar, with broad or narrow goals, and other important characteristics. Their respective policy positions and messages will show what values are important to them, and the presidential support each coalition has been achieved, or failed to achieve, will provide further insight into their effectiveness. This thesis will then apply interest group theories to the supporter and opponent coalitions. Results obtained indicate that the coalition of oil interests is large, yet very cohesive and influential, while the coalition for clean energy is large, generally diffuse but with some important

  16. Gauge invariant composite operators of QED in the exact renormalization group formalism

    CERN Document Server

    Sonoda, Hidenori

    2013-01-01

    Using the exact renormalization group (ERG) formalism, we study the gauge invariant composite operators in QED. Gauge invariant composite operators are introduced as infinitesimal changes of the gauge invariant Wilson action. We examine the dependence on the gauge fixing parameter of both the Wilson action and gauge invariant composite operators. After defining ``gauge fixing parameter independence,'' we show that any gauge independent composite operators can be made ``gauge fixing parameter independent'' by appropriate normalization. As an application, we give a concise but careful proof of the Adler-Bardeen non-renormalization theorem for the axial anomaly in an arbitrary covariant gauge by extending the original proof by A. Zee.

  17. Peer influence: neural mechanisms underlying in-group conformity.

    Science.gov (United States)

    Stallen, Mirre; Smidts, Ale; Sanfey, Alan G

    2013-01-01

    People often conform to the behavior of others with whom they identify. However, it is unclear what fundamental mechanisms underlie this type of conformity. Here, we investigate the processes mediating in-group conformity by using functional magnetic resonance imaging (fMRI). Participants completed a perceptual decision-making task while undergoing fMRI, during which they were exposed to the judgments of both in-group and out-group members. Our data suggest that conformity to the in-group is mediated by both positive affect as well as the cognitive capacity of perspective taking. Examining the processes that drive in-group conformity by utilizing a basic decision-making paradigm combined with neuroimaging methods provides important insights into the potential mechanisms of conformity. These results may provide an integral step in developing more effective campaigns using group conformity as a tool for behavioral change.

  18. Peer influence: Neural mechanisms underlying in-group conformity

    Directory of Open Access Journals (Sweden)

    Mirre eStallen

    2013-03-01

    Full Text Available People often conform to the behavior of others with whom they identify. However, it is unclear what fundamental mechanisms underlie this type of conformity. Here, we investigate the processes mediating in-group conformity by using functional magnetic resonance imaging (fMRI. Participants completed a perceptual decision-making task while undergoing fMRI, during which they were exposed to the judgments of both in-group and out-group members. Our data suggest that conformity to the in-group is mediated by both positive affect as well as the cognitive capacity of perspective taking. Examining the processes that drive in-group conformity by utilizing a basic decision-making paradigm combined with neuroimaging methods provides important insights into the potential mechanisms of conformity. These results may provide an integral step in developing more effective campaigns using group conformity as a tool for behavioral change.

  19. Individuality and social influence in groups : Inductive and deductive routes to group identity

    NARCIS (Netherlands)

    Postmes, T; Spears, R; Lee, AT; Novak, RJ

    2005-01-01

    A distinction between forms of social identity formation in small interactive groups is investigated. In groups in which a common identity is available or given, norms for individual behavior may be deduced; from group properties (deductive identity). In groups in which interpersonal relations are c

  20. Ripening influences banana and plantain peels composition and energy content.

    Science.gov (United States)

    Emaga, Thomas Happi; Bindelle, Jérôme; Agneesens, Richard; Buldgen, André; Wathelet, Bernard; Paquot, Michel

    2011-01-01

    Musa sp. peels are widely used by smallholders as complementary feeds for cattle in the tropics. A study of the influence of the variety and the maturation stage of the fruit on fermentability and metabolisable energy (ME) content of the peels was performed using banana (Yangambi Km5) and plantain (Big Ebanga) peels at three stages of maturation in an in vitro model of the rumen. Peel samples were analysed for starch, free sugars and fibre composition. Samples were incubated in the presence of rumen fluid. Kinetics of gas production were modelled, ME content was calculated using prediction equation and short-chain fatty acids production and molar ratio were measured after 72 h of fermentation. Final gas production was higher in plantain (269-339 ml g(-1)) compared to banana (237-328 ml g(-1)) and plantain exhibited higher ME contents (8.9-9.7 MJ/kg of dry matter, DM) compared to banana (7.7-8.8 MJ/kg of DM). Butyrate molar ratio decreased with maturity of the peels. The main influence of the variety and the stage of maturation on all fermentation parameters as well as ME contents of the peels was correlated to changes in the carbohydrate fraction of the peels, including starch and fibre.

  1. Maritime climate influence on chaparral composition and diversity in the coast range of central California

    Science.gov (United States)

    Vasey, Michael C; Parker, V Thomas; Holl, Karen D; Loik, Michael E; Hiatt, Seth

    2014-01-01

    We investigated the hypothesis that maritime climatic factors associated with summer fog and low cloud stratus (summer marine layer) help explain the compositional diversity of chaparral in the coast range of central California. We randomly sampled chaparral species composition in 0.1-hectare plots along a coast-to-interior gradient. For each plot, climatic variables were estimated and soil samples were analyzed. We used Cluster Analysis and Principle Components Analysis to objectively categorize plots into climate zone groups. Climate variables, vegetation composition and various diversity measures were compared across climate zone groups using ANOVA and nonmetric multidimensional scaling. Differences in climatic variables that relate to summer moisture availability and winter freeze events explained the majority of variance in measured conditions and coincided with three chaparral assemblages: maritime (lowland coast where the summer marine layer was strongest), transition (upland coast with mild summer marine layer influence and greater winter precipitation), and interior sites that generally lacked late summer water availability from either source. Species turnover (β-diversity) was higher among maritime and transition sites than interior sites. Coastal chaparral differs from interior chaparral in having a higher obligate seeder to facultative seeder (resprouter) ratio and by being dominated by various Arctostaphylos species as opposed to the interior dominant, Adenostoma fasciculatum. The maritime climate influence along the California central coast is associated with patterns of woody plant composition and β-diversity among sites. Summer fog in coastal lowlands and higher winter precipitation in coastal uplands combine to lower late dry season water deficit in coastal chaparral and contribute to longer fire return intervals that are associated with obligate seeders and more local endemism. Soil nutrients are comparatively less important in explaining plant

  2. Influence of landscape structure on the functional groups of an aphidophagous guild: Active-searching predators, furtive predators and parasitoids

    Directory of Open Access Journals (Sweden)

    Julie-Éléonore Maisonhaute

    2011-12-01

    Full Text Available A lot of studies focusing on the effect of agricultural landscapes demonstrate that many arthropod species are influenced by landscape structure. In particular, non–crop areas and landscape diversity are often associated with a higher abundance and diversity of natural enemies in fields. Numerous studies focused on the influence of landscape structure on ground beetles, spiders and ladybeetles but few on other natural enemies or different functional groups. Thus, the objective of the present study was to determine the influence of landscape structure on the functional groups, i.e., active-searching predators, furtive predators and parasitoids of aphidophagous guilds. Natural enemies were sampled on milkweed infested with aphids, growing along the borders of ditches adjacent to cornfields. The sampling occurred weekly from June to September in 2006 and 2007, in the region of Lanaudičre (Quebec, Canada. The landscapes within a radius 200 and 500 m around each site were analyzed. The abundance, richness and species composition (based on functional groups of natural enemies were related to landscape structure. The results indicated that landscape structure explained up to 21.6% of the variation in natural enemy assemblage and confirm the positive effects of non-crop areas and landscape diversity. A lower influence of landscape structure on species composition was observed (6.4 to 8.8% and varied greatly among the functional groups. Coccinellidae and furtive predators were the group most influenced by landscape structure. In conclusion, the influence of landscape varied greatly among the different species of the same functional group.

  3. What Makes a Difference for Disadvantaged Girls? Investigating the Interplay between Group Composition and Positive Youth Development in Sport

    Directory of Open Access Journals (Sweden)

    Hebe Schaillée

    2015-06-01

    Full Text Available It has been suggested that group composition can influence the experiences of individual group members in social programmes (Weiss, 1998. The purpose of the present study was to examine the relationship between peer group composition in sports programmes and positive youth development (PYD in disadvantaged girls, as well as to determine whether it was moderated by personal characteristics. Two hundred young women aged between 10 and 24 completed a questionnaire including, among others, the “Youth Experience Survey for Sport” (YES-S (MacDonald, Côté, Eys, & Deakin, 2012 and questions regarding participants’ socio-economic characteristics (i.e., nationality, education, family situation. Multilevel regression analyses were performed to take into account the hierarchical data structure. At the group level, a higher percentage of girls from a low educational track and with a migration background predicted greater PYD, as indicated by higher levels of personal and social skills, cognitive skills and goal setting. Results showed interaction effects between the respondents’ family structures on the participant and team levels. The overall statistical models for the different developmental domains accounted for variance ranging from 14.7% (personal and social skills to 30.3% (cognitive skills. Results indicated that the extent to which disadvantaged girls derive benefits from their participation in sport also depends on the group composition. The interaction effects between the group composition and individual characteristics suggest that when girls participate in a group of similar peers, those from non-intact families will derive more benefits than their counterparts from intact families.

  4. What Makes a Difference for Disadvantaged Girls? Investigating the Interplay between Group Composition and Positive Youth Development in Sport

    Directory of Open Access Journals (Sweden)

    Hebe Schaillée

    2015-06-01

    Full Text Available It has been suggested that group composition can influence the experiences of individual group members in social programmes (Weiss, 1998. The purpose of the present study was to examine the relationship between peer group composition in sports programmes and positive youth development (PYD in disadvantaged girls, as well as to determine whether it was moderated by personal characteristics. Two hundred young women aged between 10 and 24 completed a questionnaire including, among others, the “Youth Experience Survey for Sport” (YES-S (MacDonald, Côté, Eys, & Deakin, 2012 and questions regarding participants’ socio-economic characteristics (i.e., nationality, education, family situation. Multilevel regression analyses were performed to take into account the hierarchical data structure. At the group level, a higher percentage of girls from a low educational track and with a migration background predicted greater PYD, as indicated by higher levels of personal and social skills, cognitive skills and goal setting. Results showed interaction effects between the respondents’ family structures on the participant and team levels. The overall statistical models for the different developmental domains accounted for variance ranging from 14.7% (personal and social skills to 30.3% (cognitive skills. Results indicated that the extent to which disadvantaged girls derive benefits from their participation in sport also depends on the group composition. The interaction effects between the group composition and individual characteristics suggest that when girls participate in a group of similar peers, those from non-intact families will derive more benefits than their counterparts from intact families.

  5. A Primer of Social Decision Scheme Theory: Models of Group Influence, Competitive Model-Testing, and Prospective Modeling.

    Science.gov (United States)

    Stasser

    1999-10-01

    The basic elements of social decision scheme (SDS) theory are individual preferences, group preference compositions (distinguishable distributions), patterns of group influence (decision schemes, social combination rules), and collective responses (group decisions, judgments, solutions, and the like). The theory provides a framework for addressing two fundamental questions in the study of group performance: How are individual resources combined to yield a group response (the individual-into-group problem)? What are the implications of empirical observations under one set of circumstances for other conditions where data do not exist (the sparse data problem)? Several prescriptions for how to conduct fruitful group research are contained in the SDS tradition: make precise theoretical statements, provide strong and competitive tests of theories, and interpret empirical findings in the context of robust process models. Copyright 1999 Academic Press.

  6. Association between the ABO blood group and the human intestinal microbiota composition

    Directory of Open Access Journals (Sweden)

    Mäkivuokko Harri

    2012-06-01

    Full Text Available Abstract Background The mucus layer covering the human intestinal epithelium forms a dynamic surface for host-microbial interactions. In addition to the environmental factors affecting the intestinal equilibrium, such as diet, it is well established that the microbiota composition is individually driven, but the host factors determining the composition have remained unresolved. Results In this study, we show that ABO blood group is involved in differences in relative proportion and overall profiles of intestinal microbiota. Specifically, the microbiota from the individuals harbouring the B antigen (secretor B and AB differed from the non-B antigen groups and also showed higher diversity of the Eubacterium rectale-Clostridium coccoides (EREC and Clostridium leptum (CLEPT -groups in comparison with other blood groups. Conclusions Our novel finding indicates that the ABO blood group is one of the genetically determined host factors modulating the composition of the human intestinal microbiota, thus enabling new applications in the field of personalized nutrition and medicine.

  7. To What Extent Do Gestalt Grouping Principles Influence Tactile Perception?

    Science.gov (United States)

    Gallace, Alberto; Spence, Charles

    2011-01-01

    Since their formulation by the Gestalt movement more than a century ago, the principles of perceptual grouping have primarily been investigated in the visual modality and, to a lesser extent, in the auditory modality. The present review addresses the question of whether the same grouping principles also affect the perception of tactile stimuli.…

  8. To What Extent Do Gestalt Grouping Principles Influence Tactile Perception?

    Science.gov (United States)

    Gallace, Alberto; Spence, Charles

    2011-01-01

    Since their formulation by the Gestalt movement more than a century ago, the principles of perceptual grouping have primarily been investigated in the visual modality and, to a lesser extent, in the auditory modality. The present review addresses the question of whether the same grouping principles also affect the perception of tactile stimuli.…

  9. Power in group contexts: the influence of group status on promotion and prevention decision making.

    Science.gov (United States)

    Scheepers, Daan; Ellemers, Naomi; Sassenberg, Kai

    2013-06-01

    This research examines how group status affects the impact of individual power positions on promotion versus prevention choices in group decision making. We consider that high power not only implies control, but also indicates responsibility for the achievement of group goals. We argue that the nature of these goals depends on the current status of the group. In Experiment 1, individuals who were accorded high power showed more promotion-oriented decisions in the low group status condition while decisions were more prevention oriented under high group status. Experiment 2 replicated these effects, and further demonstrated that they only emerge when those in power are explicitly made accountable for the achievement of group goals. These results are discussed in relation to regulatory focus theory, power theories, and the role of social identities and group goals in group dynamics.

  10. Bion's thinking about groups: a study of influence and originality.

    Science.gov (United States)

    Schneider, John A

    2015-04-01

    One of Bion's least-acknowledged contributions to psychoanalytic theory is his study of the relationship between the mind of the individual (the ability to think), the mentalities of groups of which the individual is a member, and the individual's bodily states. Bion's early work on group therapy evolved into a study of the interplay between mind and bodily instincts associated with being a member of a group, and became the impetus for his theory of thinking. On the foundation of Bion's ideas concerning this interaction among the thinking of the individual, group mentality, and the psyche-soma, the author presents his thoughts on the ways in which group mentality is recognizable in the analysis of individuals.

  11. The Influence of Communication Processes on Group Outcomes: Antithesis and Thesis

    Science.gov (United States)

    Hewes, Dean E.

    2009-01-01

    The influence of communication processes on group outcomes is discussed from two perspectives, one in which influence does not exist and one in which influence is central. Formal models for both perspectives are presented as a means of bracketing discussion of the role of communication processes in group outcomes. The implications of these models…

  12. Calculation Method to Determine the Group Composition of Vacuum Distillate with High Content of Saturated Hydrocarbons

    Directory of Open Access Journals (Sweden)

    Nazarova Galina

    2016-01-01

    Full Text Available Calculation method to determine the group composition of the heavy fraction of vacuum distillate with high content of saturated hydrocarbons, obtained by vacuum distillation of the residue from the West Siberian oil with subsequent hydrotreating, are given in this research. The method is built on the basis of calculation the physico-chemical characteristics and the group composition of vacuum distillate according to the fractional composition and density considering with high content of saturated hydrocarbons in the fraction. Calculation method allows to determine the content of paraffinic, naphthenic, aromatic hydrocarbons and the resins in vacuum distillate with high accuracy and can be used in refineries for rapid determination of the group composition of vacuum distillate.

  13. Leader Legitimacy and Influence in Female and Male Groups.

    Science.gov (United States)

    Nochajski, Thomas H.; And Others

    A leader's legitimacy through election or appointment has been found to create differing relationships with followers, resulting generally from greater expectations for an elected leader. To compare the authority and influence of elected and appointed leaders, 140 students were recruited to participate in research on "urban planning."…

  14. Interest group influence and the delegation of police authority.

    NARCIS (Netherlands)

    Sloof, R.

    1997-01-01

    An interest group's choice between lobbying politicians and lobbying bureaucrats, and the decision ofpoliticians whether to delegate policy authority, are investigated simultaneously. Lobbying is modeledas strategic information transmission. By assumption only bureaucrats have the expertise to

  15. Influence of light curing and sample thickness on microhardness of a composite resin.

    Science.gov (United States)

    Aguiar, Flávio Hb; Andrade, Kelly Rm; Leite Lima, Débora An; Ambrosano, Gláucia Mb; Lovadino, José R

    2009-01-01

    The aim of this in vitro study was to evaluate the influence of light-curing units and different sample thicknesses on the microhardness of a composite resin. Composite resin specimens were randomly prepared and assigned to nine experimental groups (n = 5): considering three light-curing units (conventional quartz tungsten halogen [QTH]: 550 mW/cm(2) - 20 s; high irradiance QTH: 1160 mW/cm(2) - 10 s; and light-emitting diode [LED]: 360 mW/cm(2) - 40 s) and three sample thicknesses (0.5 mm, 1 mm, and 2 mm). All samples were polymerized with the light tip 8 mm away from the specimen. Knoop microhardness was then measured on the top and bottom surfaces of each sample. The top surfaces, with some exceptions, were almost similar; however, in relation to the bottom surfaces, statistical differences were found between curing units and thicknesses. In all experimental groups, the 0.5-mm-thick increments showed microhardness values statistically higher than those observed for 1- and -2-mm increments. The conventional and LED units showed higher hardness mean values and were statistically different from the high irradiance unit. In all experimental groups, microhardness mean values obtained for the top surface were higher than those observed for the bottom surface. In conclusion, higher levels of irradiance or thinner increments would help improve hybrid composite resin polymerization.

  16. Influence of light curing and sample thickness on microhardness of a composite resin

    Directory of Open Access Journals (Sweden)

    Flávio HB Aguiar

    2009-05-01

    Full Text Available Flávio HB Aguiar1, Kelly RM Andrade1, Débora AN Leite Lima1, Gláucia MB Ambrosano2, José R Lovadino11Department of Restorative Dentistry; 2Department of Social Dentistry/Statistics, Piracicaba Dental School, State University of Campinas, SP, BrazilAbstract: The aim of this in vitro study was to evaluate the influence of light-curing units and different sample thicknesses on the microhardness of a composite resin. Composite resin specimens were randomly prepared and assigned to nine experimental groups (n = 5: considering three light-curing units (conventional quartz tungsten halogen [QTH]: 550 mW/cm2 – 20 s; high irradiance QTH: 1160 mW/cm2 – 10 s; and light-emitting diode [LED]: 360 mW/cm2 – 40 s and three sample thicknesses (0.5 mm, 1 mm, and 2 mm. All samples were polymerized with the light tip 8 mm away from the specimen. Knoop microhardness was then measured on the top and bottom surfaces of each sample. The top surfaces, with some exceptions, were almost similar; however, in relation to the bottom surfaces, statistical differences were found between curing units and thicknesses. In all experimental groups, the 0.5-mm-thick increments showed microhardness values statistically higher than those observed for 1- and -2-mm increments. The conventional and LED units showed higher hardness mean values and were statistically different from the high irradiance unit. In all experimental groups, microhardness mean values obtained for the top surface were higher than those observed for the bottom surface. In conclusion, higher levels of irradiance or thinner increments would help improve hybrid composite resin polymerization.Keywords: photo-polymerization, light-curing distance, light-curing units, composite resin, composite thickness, microhardness

  17. Mountain gorilla ranging patterns: influence of group size and group dynamics.

    Science.gov (United States)

    Caillaud, Damien; Ndagijimana, Felix; Giarrusso, Anthony J; Vecellio, Veronica; Stoinski, Tara S

    2014-08-01

    Since the 1980s, the Virunga mountain gorilla population has almost doubled, now reaching 480 individuals living in a 430-km(2) protected area. Analysis of the gorillas' ranging patterns can provide critical information on the extent and possible effects of competition for food and space. We analyzed 12 years of daily ranging data and inter-group encounter data collected on 11 gorilla groups monitored by the Karisoke Research Center in Rwanda. During that period, the study population increased in size by almost 50% and the number of groups tripled. Groups had small yearly home ranges compared to other known gorilla populations, with an average 90% kernel density estimate of 8.07 km2 and large between-group variations (3.17-23.59 km2). Most groups had consistent home range location over the course of the study but for some, we observed gradual range shifts of up to 4 km. Neighboring groups displayed high home range overlap, which increased dramatically after the formation of new groups. On average, each group used only 28.6% of its 90% kernel home range exclusively, and in some areas up to six different groups had overlapping home ranges with little or no exclusive areas. We found a significant intra-group positive relationship between the number of weaned individuals in a group and the home range size, but the fitted models only explained 17.5% and 13.7% of the variance in 50% and 90% kernel home range size estimates, respectively. This suggests that despite the increase in size, the study population is not yet experiencing marked effects of feeding competition. However, the increase in home range overlap resulting from the formation of new groups led to a sixfold increase in the frequency of inter-group encounters, which exposes the population to elevated risks of fight-related injuries and infanticide.

  18. To what extent do Gestalt grouping principles influence tactile perception?

    Science.gov (United States)

    Gallace, Alberto; Spence, Charles

    2011-07-01

    Since their formulation by the Gestalt movement more than a century ago, the principles of perceptual grouping have primarily been investigated in the visual modality and, to a lesser extent, in the auditory modality. The present review addresses the question of whether the same grouping principles also affect the perception of tactile stimuli. Although, to date, only a few studies have explicitly investigated the existence of Gestalt grouping principles in the tactile modality, we argue that many more studies have indirectly provided evidence relevant to this topic. Reviewing this body of research, we argue that similar principles to those reported previously in visual and auditory studies also govern the perceptual grouping of tactile stimuli. In particular, we highlight evidence showing that the principles of proximity, similarity, common fate, good continuation, and closure affect tactile perception in both unimodal and crossmodal settings. We also highlight that the grouping of tactile stimuli is often affected by visual and auditory information that happen to be presented simultaneously. Finally, we discuss the theoretical and applied benefits that might pertain to the further study of Gestalt principles operating in both unisensory and multisensory tactile perception.

  19. [Influence of diesel fuel on the number of selected soil microorganisms group].

    Science.gov (United States)

    Hawrot-Paw, Małgorzata

    2012-01-01

    Among a range of xenobiotics, that are introduced into the environment, especially dangerous are petroleum substances. Microorganisms participating in their decomposition, may be a good effectiveness indicator of biodegradation process. The aim of this study was to determine the influence of soil contamination with diesel oil for changes in number of basic taxonomic groups of microorganisms, including bacteria, actinomycetes and fungi. The study was carried out in two soils, loamy sand and sandy clay, which, apart from granulometric composition also differed in organic matter content. Two levels of diesel contamination was used: 5% and 15% w/w of soil d.m. The soil samples, not contaminated with diesel oil, was left as a experience control objects. The number of microorganisms were evaluated by automated method with measuring impedance in media, using the analyzer BacTrac 4100. In the studied soils the largest group of microorganisms were bacteria, significantly less was fungi and actinomycetes. Based on the results of research it was found a significant effect on the quantitative composition of microflora was both contamination dose and type of soil. Diesel fuel at a concentration of 5% stimulated the number of bacteria and fungi in sandy soil. In general, increase in concentration of pollutants adversely affect the microorganisms, especially in loamy soils. Soil contamination with diesel oil resulted in a reduction in the degree of microbial growth rate (55% in loamy sand and 39% in sandy clay), and thus have an impact on their fertility. The reduction of SR index was correlated with increasing dose of pollutants. Diesel oil affect the biological balance of soil and stimulates or reduces the number of different groups of microorganisms, depending on the amount of fuel. The presence of fuel decrease index of soil fertility, proportion to increase in the level of contamination.

  20. Influence of Group Formation Choices on Academic Performance

    Science.gov (United States)

    Seethamraju, Ravi; Borman, Mark

    2009-01-01

    With its multidisciplinary and applied foci, team-working skills are seen as especially critical in business courses in general and in business information systems courses in particular, and are specifically incorporated into desired graduate attributes by many universities. Past research has focused on the benefits of group working but little…

  1. Peer influence: neural mechanisms underlying in-group conformity

    NARCIS (Netherlands)

    Stallen, Mirre; Smidts, A.; Sanfey, A.G.

    2013-01-01

    People often conform to the behavior of others with whom they identify. However, it is unclear what fundamental mechanisms underlie this type of conformity. Here, we investigate the processes mediating in-group conformity by using functional magnetic resonance imaging (fMRI). Participants completed

  2. Peer influence: Neural mechanisms underlying in-group conformity

    NARCIS (Netherlands)

    M. Stallen (Mirre); A. Smidts (Ale); A.G. Sanfey (Alan)

    2013-01-01

    textabstractPeople often conform to the behavior of others with whom they identify. However, it is unclear what fundamental mechanisms underlie this type of conformity. Here, we investigate the processes mediating in-group conformity by using functional magnetic resonance imaging (fMRI). Participant

  3. The Influence of Group Size on Children's Competitive Behavior.

    Science.gov (United States)

    Benenson, Joyce F.; Nicholson, Catherine; Waite, Angela; Roy, Rosanne; Simpson, Anna

    2001-01-01

    Tested hypothesis that children would compete more playing competitive games in tetrads than in dyads. Found that male target children competed more in tetrads than in dyads; female target children did not show different levels of competition based on group size. Based on a global measure of smiling, the emotional atmosphere was less positive in…

  4. Peer influence: neural mechanisms underlying in-group conformity

    NARCIS (Netherlands)

    Stallen, Mirre; Smidts, A.; Sanfey, A.G.

    2013-01-01

    People often conform to the behavior of others with whom they identify. However, it is unclear what fundamental mechanisms underlie this type of conformity. Here, we investigate the processes mediating in-group conformity by using functional magnetic resonance imaging (fMRI). Participants completed

  5. Peer influence: Neural mechanisms underlying in-group conformity

    NARCIS (Netherlands)

    M. Stallen (Mirre); A. Smidts (Ale); A.G. Sanfey (Alan)

    2013-01-01

    textabstractPeople often conform to the behavior of others with whom they identify. However, it is unclear what fundamental mechanisms underlie this type of conformity. Here, we investigate the processes mediating in-group conformity by using functional magnetic resonance imaging (fMRI).

  6. 112 fadama users group characteristics that influence facilitators ...

    African Journals Online (AJOL)

    2010-03-01

    Mar 1, 2010 ... cultivation, mono cropping, mixed cropping ... Nigeria into three regions based on ecological .... realized by using the logit regression model. ... extension performance (Leonard, 1977). The .... This implies negative effect on effective role ..... Fadama users group variable. Estimated. Standard error. R-value.

  7. Synthesis of cross-linked magnetic composite microspheres containing carboxyl groups

    Institute of Scientific and Technical Information of China (English)

    Jili ZHAO; Zhaorang HAN; Qiang SONG; Ying WANG; Dan SUN

    2008-01-01

    Fe3O4 magnetic nano-particles were prepared by a co-precipitation method and were modified using oleic acid. Then, the cross-linked magnetic composite microspheres containing a carboxyl group were prepared by using an improved emulsion polymerization with divinylbenzene (DVB) as the cross-linking agent. The composite microspheres comprised the Fe3O4 magnetic nano-partictes as cores and the copolymer of styrene and acrylic acid as shells. The morphology and structure of the composite microsphere were characterized by FT-IR, transmission electron microscopy (TEM), X-ray diffrac-tion (XRD), X-ray photoelectron spectrum (XPS) and so on. The results show that the composite microspheres were well dispersed in emulsion with uniform sizes and carboxyl groups on their surface. They were cross-linked and stable in 1 mol/L of HCl and DMF.

  8. Anisotropic enhancement of group velocity in a homogenized dielectric composite medium

    OpenAIRE

    Mackay, Tom G.; Lakhtakia, Akhlesh

    2005-01-01

    Under certain circumstances, the group velocity in a homogenized composite medium (HCM) can exceed the group velocity in its component material phases. We explore this phenomenon for a uniaxial dielectric HCM comprising isotropic component material phases distributed as oriented spheroidal particles. The theoretical approach is based upon the Bruggeman homogenization formalism. Enhancement in group velocity in the HCM with respect to the component material phases is shown to be sensitively de...

  9. The influence of matrix composition and reinforcement type on the properties of polysialate composites

    Science.gov (United States)

    Hammell, James A.

    There is a critical need for the development of materials for eliminating fire as a cause of death in aircraft accidents. Currently available composites that use organic matrices not only deteriorate at temperatures above 300°C but also emit toxic fumes. The results presented in this dissertation focus on the development of an inorganic matrix that does not burn or emit toxic fumes. The matrix, known as polysialate, can withstand temperatures in excess of 1000°C. The matrix behaves like a ceramic, but does not need high curing temperatures, so it can be processed like many common organic matrices. The major parameters evaluated in this dissertation are: (i) Influence of reinforcement type, (ii) Matrix formulation for both wet-dry durability and high temperature resistance, (iii) Influence of processing variables such as moisture reduction and storage, (iv) Tensile strain capacity of modified matrices and matrices reinforced with ceramic microfibers and discrete carbon fibers, and (v) analytical modeling of mechanical properties. For the reinforcement type; carbon, glass, and stainless steel wire fabrics were investigated. Carbon fabrics with 1, 3, 12, and 50k tows were used. A matrix chemical formulation that can withstand wetting and drying was developed. This formulation was tested at high temperatures to ascertain its stability above 400°C. On the topic of processing, shelf life of prepregged fabric layers and efficient moisture removal methods were studied. An analytical model based on layered reinforcement was developed for analyzing flexural specimens. It is shown that the new inorganic matrix can withstand wetting and drying, and also high temperature. The layered reinforcement concept provides accurate prediction of strength and stiffness for composites reinforced with 1k and 3k tows. The prepregged fabric layers can be stored for 14 days at -15°C without losing strength.

  10. The influence of group membership on young children's prosocial behaviour.

    Science.gov (United States)

    Over, Harriet

    2017-08-08

    Young children can be extremely prosocial-willing to help and share with others and comfort them in distress. However, the origins of social problems like prejudice and discrimination also appear early in development. In this paper, I discuss research investigating how group membership affects children's tendency to be prosocial. Existing research on this topic has focused primarily on sharing behaviour and shown that, in general, children allocate more resources to members of their own groups. After reviewing this important literature, I make the case for extending research with young children to other forms of prosociality. This has the potential to inform our understanding of the mechanisms behind ingroup favouritism in prosociality and help us understand routes towards interventions to encourage more egalitarian behaviour. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Parity Influences the Demeanor of Sows in Group Housing.

    Science.gov (United States)

    Clarke, Taya; Pluske, John R; Miller, David W; Collins, Teresa; Fleming, Patricia A

    2017-08-28

    Across the globe, producers are moving from individual housing to group housing for sows during gestation. Producers typically group sows of a range of parities together, although the impacts are largely unknown. This study examined the behavioral expression at mixing for young, midparity, and older sows. Ten mixed-parity groups were filmed at mixing on a commercial piggery. One-minute clips were edited from continuous footage where focal sows of known parity could be identified, and scored for qualitative behavioral expression. Parity 2 and 6 sows were more calm/tired than Parity 4 sows, who were more active/energetic. Parity 2 sows were more curious/inquisitive than Parity 4 and 6 sows, who were more anxious/frustrated. Correlations between qualitative behavioral expression and activity indicated sows scored as more calm/tired spent a greater proportion of time standing, while sows scored as more active/energetic spent more time performing avoidance behavior. Different body language is likely to reflect physical or affective differences in how sows cope with mixing.

  12. Influence of curing rate of resin composite on the bond strength to dentin

    DEFF Research Database (Denmark)

    Benetti, Ana Raquel; Asmussen, E; Peutzfeldt, A

    2007-01-01

    This study determined whether the strength with which resin composite bonds to dentin is influenced by variations in the curing rate of resin composites. Resin composites were bonded to the dentin of extracted human molars. Adhesive (AdheSE, Ivoclar Vivadent) was applied and cured (10 seconds...

  13. Sow and litter factors influencing colostrum yield and nutritional composition.

    Science.gov (United States)

    Declerck, I; Dewulf, J; Piepers, S; Decaluwé, R; Maes, D

    2015-03-01

    One of the main characteristics of colostrum intake (CI), colostrum yield (CY), and colostrum composition (CC) in pigs is its variability. The present observational study aimed to investigate factors influencing CY and CC in 10 commercial herds. In total, 100 sows of 5 different breeds and their 1,455 live-born piglets were included. Sows' CY was estimated by the CI of their suckling piglets. Colostrum composition was analyzed by LactoScope Fourier transform infrared spectroscopy. Colostrum yield averaged 3,500 ± 110 g and the percentage of colostral fat (CF), protein, and lactose in colostrum averaged 5.39 ± 0.12, 16.49 ± 0.14, and 2.02 ± 0.05 %, respectively. The effect of sow, litter, and parturition factors on CY and CC were evaluated with a linear mixed regression model with herd included as a random factor. Sows with a gestation length (GL) of 113 d had a higher CY (4,178 ± 506 g) than sows with a GL of 114 to 115 d (3,342 ± 107 g; = 0.04). An interaction was found between the litter birth weight of suckling piglets (LW) and GL ( = 0.03). In sows with a GL of 114 to 115 d, CY increased with higher LW ( = 0.009). A shorter interval between birth and first suckling of the litter was related to a higher CY ( colostrums was higher in Hypor sows (6.35 ± 0.51) than in PIC (4.98 ± 0.27; = 0.001), Topigs 20 (5.05 ± 0.14; < 0.001), and Danbred (5.34 ± 0.22; < 0.001) sows. The percentage of CF was negatively associated with parity ( = 0.02) and positively associated with the number of live-born piglets ( = 0.03). The percentages of colostral protein and lactose were not significantly associated with any factor in the multivariable model. In conclusion, this study demonstrated that CY and CF are affected by different sow and litter factors. Pig producers may implement these observations in their management to maximize production or reproduction potential by optimizing CI, CY, and CC.

  14. How do local government associations influence policy? Assessing conditions for policy influence of interest groups in Brazil and the Netherlands

    NARCIS (Netherlands)

    A. Macedo de Jesus (Anderson)

    2010-01-01

    markdownabstract__Abstract__ In recent years a considerable number of studies have been undertaken concerning the impact of interest groups' influence in the European and North American policy-making process.

  15. The effect of interventions on Twitter in four target groups using different measures of influence

    NARCIS (Netherlands)

    Maanen, P.P. van; Wijn, R.; Boertjes, E.

    2014-01-01

    In this paper, the influence of interventions on Twitter users is studied. We define influence in (a) number of participants, (b) size of the audience, (c) amount of activity, and (d) reach. Influence is studied for four different target groups: (a) politicians, (b) journalists, (c) employees and (d

  16. The effect of interventions on Twitter in four target groups using different measures of influence

    NARCIS (Netherlands)

    Maanen, P.P. van; Wijn, R.; Boertjes, E.

    2014-01-01

    In this paper, the influence of interventions on Twitter users is studied. We define influence in (a) number of participants, (b) size of the audience, (c) amount of activity, and (d) reach. Influence is studied for four different target groups: (a) politicians, (b) journalists, (c) employees and (d

  17. Influence of controlled and uncontrolled interventions on Twitter in different target groups

    NARCIS (Netherlands)

    Maanen, P.P. van; Aarts, O.; Boertjes, E.; Wijn, R.

    2013-01-01

    In this paper the influence of interventions on Twitter users is studied. We define influence in a) number of participants, b) size of the audience, c) amount of activity, and d) reach. Influence is studied for four different target groups: a) politicians, b) journalists, c) employees and d) the gen

  18. Does taxonomic diversity in indicator groups influence their effectiveness in identifying priority areas for species conservation?

    DEFF Research Database (Denmark)

    Bladt, Jesper Stentoft; Larsen, Frank Wugt; Rahbek, Carsten

    2008-01-01

    the taxonomic diversity in species indicator groups influence their effectiveness in the identification of priority areas for species conservation. We tested whether indicator groups comprising a higher taxonomic diversity (i.e. indicator groups consisting of species from many different taxonomic groups...

  19. The cross-linking influence of electromagnetic radiation on water-soluble polyacrylan compositions with biopolymers

    Directory of Open Access Journals (Sweden)

    B. Grabowska

    2009-01-01

    Full Text Available The results of examinations of the cross-linking influence of electromagnetic radiation - in a microwave range – on polyacrylancompositions with biopolymers, are presented in the hereby paper. The cross-linking process of the tested compositions was determined on the basis of the FT-IR spectroscopic methods. It was shown that microwave operations can lead to the formation of new cross-linkedstructures with strong covalent bonds. The adsorption process and formation of active centres in polymer molecules as well as in highsilica sand were found due to microwave radiations. In this process hydroxyl groups (-OH - present in a polymer - and silane groups (Si- O-H - present in a matrix - are mainly taking part. Spectroscopic and strength tests performed for the system: biopolymer binding agent – matrix indicate that the microwave radiation can be applied for hardening moulding sands with biopolymer binders.

  20. Learning Science in Small Multi-Age Groups: The Role of Age Composition

    Science.gov (United States)

    Kallery, Maria; Loupidou, Thomais

    2016-01-01

    The present study examines how the overall cognitive achievements in science of the younger children in a class where the students work in small multi-age groups are influenced by the number of older children in the groups. The context of the study was early-years education. The study has two parts: The first part involved classes attended by…

  1. Social influence in computer-mediated communication : The effects of anonymity on group behavior

    NARCIS (Netherlands)

    Postmes, T; Spears, R; Sakhel, K; de Groot, D

    2001-01-01

    Two studies examined hypotheses derived from a Social Identity model of Deindividuation Effects (SIDE) as applied to social influence in computer-mediated communication (CMC) in groups. This model predicts that anonymity can increase social influence if a common group identity is salient. In a first

  2. Grouping by Closure Influences Subjective Regularity and Implicit Preference

    Directory of Open Access Journals (Sweden)

    Alexis Makin

    2012-09-01

    Full Text Available A reflection between a pair of contours is more rapidly detected than a translation, but this effect is stronger when the contours are closed to form a single object compared to when they are closed to form 2 objects with a gap between them. That is, grouping changes the relative salience of different regularities. We tested whether this manipulation would also change preference for reflection or translation. We measured preference for these patterns using the Implicit Association Test (IAT. On some trials, participants saw words that were either positive or negative and had to classify them as quickly as possible. On interleaved trials, they saw reflection or translation patterns and again had to classify them. Participants were faster when 1 button was used for reflection and positive words and another button was used for translation and negative words, compared to when the reverse response mapping was used (translation and positive vs. reflection and negative. This reaction time difference indicates an implicit preference for reflection over translation. However, the size of the implicit preference was significantly reduced in the Two-objects condition. We concluded that factors that affect perceptual sensitivity also systematically affect implicit preference formation.

  3. Influence of paragenetic factors on production and chemical composition of Paška sheep milk

    Directory of Open Access Journals (Sweden)

    Dubravka Samaržija

    2011-09-01

    Full Text Available Since the produced Paška sheep milk is entirely processed in Pag cheese, it is of great importance to ensure a uniform milk production of prescribed chemical composition and hygienic quality. In addition to genotype, as the most important factor, the production and quality of sheep milk is affected by numerous physiological factors, so the aim of this research was to determine the influence of paragenetic factors (stage and number of lactation on daily milk yield and chemical composition (total solids, milk fat, protein, casein, lactose, total solids non fat of Paška sheep milk. Three herds were chosen by random selection within the areas of Kolan and Caska, and survey was conducted on a total of 213 Paška sheep. Stage of lactation was divided to: the beginning (to 50th-day, the middle (from 51st till 100thday and the end (101st -day till dry out of lactation. Depending on the number of lactation, sheep were grouped into five groups (1st, 2nd, 3rd, 4th, 5th and others. A significant influence of stage and number of lactation on average daily milk yield and analysed chemical composition parameters was determined. The Paška sheep had the highest daily milk production in the mid lactation (773 g, and the third lactation (712 g recorded. At the end of lactation, total solids, milk fat, protein, casein, total solids non fat in milk were significantly higher than at the beginning and middle of lactation. The highest share of total solids, milk fat, protein and casein was determined in Paška sheep milk at 5th lactation and other lactations. Between the individual parameters significantcorrelation coefficients were determined.

  4. The effect of group composition on the welfare of African catfish (Clarias gariepinus)

    NARCIS (Netherlands)

    Martins, C.I.; Schrama, J.W.; Verreth, J.A.J.

    2006-01-01

    Within fish farming grading, i.e. the process of sorting to approximate size, changes the group composition from heterogeneous to homogeneous. Although this procedure is considered an acute stressor, the long-term consequences of grading on aggression and stress levels have not yet been investigated

  5. Students with special needs and the composition of their peer group

    NARCIS (Netherlands)

    Pijl, Sip Jan; Skaalvik, Einar M.; Skaalvik, Sidsel

    2010-01-01

    One of the effects of implementing inclusive education is that the composition of the peer group of students with disabilities has changed from one consisting of only such students to one with no, or very few, students with disabilities. The question arises as to the implications of this situation f

  6. The group velocity variation of Lamb wave in fiber reinforced composite plate.

    Science.gov (United States)

    Rhee, Sang-Ho; Lee, Jeong-Ki; Lee, Jung-Ju

    2007-12-01

    Experimentally measured Lamb wave group velocities in composite materials with anisotropic characteristics are not the same as the theoretical group velocities which is calculated with the Lamb wave dispersion equation. This discrepancy arises from the fact that the angle between the group velocity direction and the phase velocity direction in anisotropic materials exists. Wave propagation in a composite material with anisotropic characteristics should be considered with respect to magnitude correction in addition to direction correction. In this study, S0 mode phase velocity dispersion curves are depicted with the variation of degree with respect to the fiber direction using a Lamb wave dispersion relation in the unidirectional, bidirectional, and quasi-isotropic composite plates. Slowness surface is sketched by the reciprocal value of the phase velocity curves. The magnitude and direction of the group velocity could be calculated from the slowness surface. The recalculated group velocities with consideration of the magnitude and direction from the slowness surface are compared with experimentally measured group velocities. The proposed method shows good agreements with theoretical and experimental results.

  7. Influence of Bicurative on Processibility of Composite Propellant

    Directory of Open Access Journals (Sweden)

    S.N. Jawalkar

    2007-09-01

    Full Text Available A new series of composite propellant compositions, based on ammonium perchlorate,hydroxy-terminated polybutadiene and having metallic fuel as aluminium powder, have beendeveloped. Pressure cast-cum-cured compositions have also been developed with toluenediisocyanate (TDI, isophorone diisocyanate (IPDI, and a mixture of both curatives, i.e., TDIand IPDI, respectively, to study their effect on processibility, mechanical and ballistic propertiesof the compositions.  The data indicate that the compositions based on bicurative have a potlife of 7 - 8 h, viscosity build up is from 13280 poise to 14080 poise after 4 h, and the smoothprocessibility of the slurry is enhanced. Further, the mechanical properties are in the range12.2 kg/cm2, 40.2 kg/cm2, and 40.2 per cent for tensile strength, E-modulus and elongation,respectively, and burn rate is almost the same, i.e., 16 ±0.5 mm/s.

  8. Influence of the distance of the curing light source and composite shade on hardness of two composites.

    Science.gov (United States)

    Thomé, Thaís; Steagall, Washington; Tachibana, Arlene; Braga, Sheila Regina Maia; Turbino, Miriam Lacalle

    2007-12-01

    This study evaluated the influence of curing tip distance, shade and filler particle size on Vickers microhardness (VHN) of composite resins. Two composites were tested: Filtek Z250 microhybrid (3M ESPE; shades A1 and A3.5) and Filtek Supreme nanofilled (3M ESPE; shades A1B and A3.5B). For each resin, 42 specimens (5 mm in diameter and 2 mm height) were prepared being 21 for each shade. The specimens were exposed using a 20-second exposure to a quartz-tungsten-halogen light source with an irradiance of approximately 560 mW/cm(2), at the following distances: 0 mm (surface contact), 6 mm and 12 mm from composite surface. Effectiveness of cure of different resins, shades and curing distances was determined by measuring the top and bottom hardness (VHN) of specimens using a digital microhardness tester (load: 50 g; dwell time: 45 seconds) 24 hours following curing. The hardness ratio was calculated by dividing VHN of the bottom surface by VHN of top surface. Three-way ANOVA and Tukey's post-hoc test (phardness, as microhardness ratio (bottom/top), the factors shade, distance and composite filler particle size exerted influence on resin curing. Lighter shade composites (A1 and A1B) showed higher hardness values. At 6 and 12 mm curing tip distances, hardness was lower when compared to 0 mm. The microhybrid composite resin presented higher hardness, being its microhardness ratio satisfactory only at 0 mm for both shades and at 6 mm for the lighter shade. The nanofilled composite resin did not present satisfactory microhardness at the bottom while the microhybrid composite resin had higher hardness than the nanofilled. Composite's curing tip distance and shade can influence hardness.

  9. Influence of the distance of the curing light source and composite shade on hardness of two composites

    Directory of Open Access Journals (Sweden)

    Thaís Thomé

    2007-12-01

    Full Text Available This study evaluated the influence of curing tip distance, shade and filler particle size on Vickers microhardness (VHN of composite resins. Two composites were tested: Filtek Z250 microhybrid (3M ESPE; shades A1 and A3.5 and Filtek Supreme nanofilled (3M ESPE; shades A1B and A3.5B. For each resin, 42 specimens (5 mm in diameter and 2 mm height were prepared being 21 for each shade. The specimens were exposed using a 20-second exposure to a quartz-tungsten-halogen light source with an irradiance of approximately 560 mW/cm², at the following distances: 0 mm (surface contact, 6 mm and 12 mm from composite surface. Effectiveness of cure of different resins, shades and curing distances was determined by measuring the top and bottom hardness (VHN of specimens using a digital microhardness tester (load: 50 g; dwell time: 45 seconds 24 hours following curing. The hardness ratio was calculated by dividing VHN of the bottom surface by VHN of top surface. Three-way ANOVA and Tukey's post-hoc test (p<0.05 revealed statistically significant differences for all analyzed factors. As for top hardness, as microhardness ratio (bottom/top, the factors shade, distance and composite filler particle size exerted influence on resin curing. Lighter shade composites (A1 and A1B showed higher hardness values. At 6 and 12 mm curing tip distances, hardness was lower when compared to 0 mm. The microhybrid composite resin presented higheer hardness, being its microhardness ratio satisfactory only at 0 mm for both shades and at 6 mm for the lighter shade. The nanofilled composite resin did not present satisfactory microhardness at the bottom while the microhybrid composite resin had higher hardness than the nanofilled. Composite's curing tip distance and shade can influence hardness.

  10. Area group: an example of style and paste compositional covariation in Maya pottery

    Energy Technology Data Exchange (ETDEWEB)

    Bishop, R.L.; Reents, D.J.; Harbottle, G.; Sayre, E.V.; van Zelst, L.

    1983-06-12

    This paper has addressed aspects of ceramic style and iconography as found in Late Classic Maya ceramic art, including the supplemental perspective afforded by the analysis of ceramic paste. The chemical data provide a means to assess the extent of stylistic-paste compositional covariation. Depending upon the strength of that covariation various inferences may be drawn about craft specialization, exchange and information flow within Maya society. At the least, it provides an empirical means of comparing stylistically similar vessels; and when they are members of a chemically homogeneous group, it permits style to be addressed in terms of its variation. Additionally, compositionally defined site or region specific reference units provide a chemical background against which the non-provenienced vessels may be compared, allowing the whole vessels to be related to the archaelogically recovered fragmentary material. Finally, this multidisciplinary approach has been illustrated by preliminary findings concerning a specific group of polychrome vessels, The Area Group.

  11. Reinforcing graphene oxide/cement composite with NH$_2$ functionalizing group

    Indian Academy of Sciences (India)

    M EBRAHIMIZADEH ABRISHAMI; V ZAHABI

    2016-08-01

    In this study, pure and NH$_2$-functionalized graphene oxide (GO) nanosheets have been added to the cement mortar with different weight percents (0.05, 0.10, 0.15, 0.20 and 0.25 wt%). In addition, the effects of functionalizing GO on the microstructure and mechanical properties (flexural/compressive strengths) of cement composite have been investigated for the first time. Scanning electron microscopy (SEM) images showed that GO filledthe pores and well dispersed in concrete matrix, whereas exceeding GO additive from 0.10 wt% caused the formation of agglomerates and microcracks. In addition, mercury intrusion porosimetry confirmed the significant effects of GO and functionalizing groups on filling the pores. NH2-functionalizing helped to improve the cohesion between GO nanosheets and cement composite. Compressive strengths increased from 39 MPa for the sample without GO to54.23 MPa for the cement composites containing 0.10 wt% of NH$_2$-functionalized GO. Moreover, the flexural strength increased to 23.4 and 38.4% by compositing the cement paste with 0.10 wt% of pure and NH$_2$-functionalized GO, compared to the sample without GO, respectively. It was shown that functionalizing considerably enhanced the mechanical properties of GO/cement composite due to the interfacial strength between calcium silicatehydrates (C-S-H) gel and functionalized GO nanosheets as observed in SEM images. The morphological results were in good agreement with the trend obtained in mechanical properties of GO/cement composites.

  12. Methods and compositions for diagnosing and preventing a group B streptococcal infection

    Science.gov (United States)

    Brady, Linda Jeannine; Seifert, Kyle N.; Adderson, Elisabeth E.; Bohnsack, John F.

    2009-09-15

    The present invention provides a group B streptococcal (GBS) surface antigen, designated epsilon antigen, that is co-expressed with the delta antigen on a subset of serotype III GBS. Epsilon is expressed on more pathogenic Restriction Digest Pattern (RDP) III-3 GBS, but not on RDP types 1, 2, or 4. Accordingly, the present invention provides compositions and methods for detecting a group B streptococcus serotype III, RDP III-3 strain. Vaccines and methods of identifying agents which inhibit adhesion of a group B streptococcal cell to a host cell are also provided.

  13. Intraoral environment conditions and their influence on marginal leakage in composite resin restorations.

    Science.gov (United States)

    Mathias, Paula; Rocha, Viviane; Saraiva, Letícia; Cavalcanti, Andrea N; Azevedo, Juliana F; Paulillo, Luís Alexandre M S

    2010-01-01

    Color matching in the anterior superior incisor region (ASIR) is very difficult when using a rubber dam during restorative procedures. This study measured temperature/relative humidity parameters in the ASIR and evaluated the influence of the inhalation/downtime/exhalation mouth-breathing cycle on microleakage in composite resin restorations performed in the region, using three different adhesive systems. Sixty bovine incisors were randomly assigned to six groups (n=10) according to environmental conditions (laboratory environment or intraoral conditions) and the three adhesive systems being tested (Prime & Bond NT (PB), Single Bond (SB) and Clearfil SE Bond (CL)). The composite resin restored specimens were thermocycled (800 cycles, 5-55 degrees C), immersed in a 2% methylene blue-buffered solution and sectioned longitudinally The dye penetration on the margin of the restoration was evaluated and non-parametric statistical analyses were performed. The temperature and humidity parameters in the ASIR showed significant differences when compared to the laboratory environment. Restorations performed in the ASIR environment showed no increases in microleakage. As it was shown that temperature/humidity in ASIR do not affect marginal sealing in direct composite resin restorations negatively, better color matching can be safely achieved without the use of a rubber dam.

  14. Research on the influence of content of vitrinoid group and content of inert group to CO adsorption-proliferation quantity

    Institute of Scientific and Technical Information of China (English)

    XIAO Cang-yan; GUO Li-wen; ZHENG Ning

    2009-01-01

    Dispersed coal was analyzed and rock experiment was conducted on four coals of medium-low rank in the aspect of coal and rock configuration,which resulted in eight coal samples mostly of the vitrinoid group or inert group.Then,an adsorption experiment of CO under different temperatures and pressures as well as a diffusion experiment under normal temperature and pressure were conducted.The research results indicate that for medium-low rank coal,because the pore structure in the inert group is bigger than that in the vitrinoid group,the influence on CO adsorption-proliferation of the inert group is bigger than that in the vitrinoid group,and the adsorption quantity of the inert group is more sus-ceptive.The difference of adsorption quantity between the two groups diminish along with the improvement of coalification degree.The difference of adsorption quantity between the two groups shows no obvious change along with the change of temperature.

  15. One angry woman: Anger expression increases influence for men, but decreases influence for women, during group deliberation.

    Science.gov (United States)

    Salerno, Jessica M; Peter-Hagene, Liana C

    2015-12-01

    We investigated whether expressing anger increases social influence for men, but diminishes social influence for women, during group deliberation. In a deception paradigm, participants believed they were engaged in a computer-mediated mock jury deliberation about a murder case. In actuality, the interaction was scripted. The script included 5 other mock jurors who provided verdicts and comments in support of the verdicts; 4 agreed with the participant and 1 was a "holdout" dissenter. Holdouts expressed their opinions with no emotion, anger, or fear and had either male or female names. Holdouts exerted no influence on participants' opinions when they expressed no emotion or fear. Participants' confidence in their own verdict dropped significantly, however, after male holdouts expressed anger. Yet, anger expression undermined female holdouts: Participants became significantly more confident in their original verdicts after female holdouts expressed anger-even though they were expressing the exact same opinion and emotion as the male holdouts. Mediation analyses revealed that participants drew different inferences from male versus female anger, which created a gender gap in influence during group deliberation. The current study has implications for group decisions in general, and jury deliberations in particular, by suggesting that expressing anger might lead men to gain influence, but women to lose influence over others (even when making identical arguments). These diverging consequences might result in women potentially having less influence on societally important decisions than men, such as jury verdicts.

  16. Understanding the Influence of Organizational Culture and Group Dynamics on Organizational Change and Learning

    Science.gov (United States)

    Lucas, Colleen; Kline, Theresa

    2008-01-01

    Purpose: The purpose of this study is to investigate the relationship between organizational culture, group dynamics, and organizational learning in the context of organizational change. Design/methodology/approach: A case study was used to examine cultural and group level factors that potentially influence groups' learning in the context of…

  17. Understanding the Influence of Organizational Culture and Group Dynamics on Organizational Change and Learning

    Science.gov (United States)

    Lucas, Colleen; Kline, Theresa

    2008-01-01

    Purpose: The purpose of this study is to investigate the relationship between organizational culture, group dynamics, and organizational learning in the context of organizational change. Design/methodology/approach: A case study was used to examine cultural and group level factors that potentially influence groups' learning in the context of…

  18. Influence of Particle Size on Piezoelectricity of Piezo-composites

    Institute of Scientific and Technical Information of China (English)

    LUO Dabing; LIU Hanxing; HAO Hua; LI Yanfeng; OUYANG Shixi

    2007-01-01

    Serial material model (Dilute model)and Limited Units (LU)method were employed to analyze the performance of binary piezo-composite system. The reckoned electric potential deployments illustrated difference while the particles were different. Their piezoelectricities were also calculated according to the model,and furthermore comparation suggested that small particles living in the tolerance improve the piezoelectricity of piezo-composite. Experiments coinciding with analyses were processed simultaneously.Ceramics were milled for different time in order to control the concentration of particle size.The results showed that the filled particles enhanced the piezoelectricity of binary piezo-composite system efficiently whereas too many chips deteriorated the performance of piezo-composites.

  19. Influence of particle structure on electrochemical character of composite graphite

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The natural graphite has been used as the anode material for Lithium-Ion batteries, because of its low cost, chemical stability and excellent reversibility for Li+ insertion. However, the slow diffusion rate of lithium ion and poor compatibility with electrolyte solutions make it difficult to use in some conditions. In order to solve these problems, an epoxy-coke/graphite composite has been manufactured. The particle of composite carbonaceous material coated on non-graphitizable (hard) carbon matrix. Due to the disordered structure,the diffusion rate of lithium species in the non-graphitzable carbon is remarkably fast and less anisotropic. The process for preparing a composite carbon powder provides a promising new anode material with superior electrochemical properties for Li-ion batteries. The unique structure of epoxy-coke/graphite composite electrodes results in much better kinetics, also better recharge ability and initial charge/discharge efficiency.

  20. [Influence of primers ' chemical composition on shear bond strength of resin cement to zirconia ceramic].

    Science.gov (United States)

    Łagodzińska, Paulina; Bociong, Kinga; Dejak, Beata

    2014-01-01

    Resin cements establish a strong durable bond between zirconia ceramic and hard tissues of teeth. It is essential to use primers with proper chemical composition before cementation. The aim of this study was to assess the influence of primer's chemical composition on the shear bond strength of zirconia ceramic to resin cements. 132 zirconia specimens were randomly assigned to four groups. There were four resin systems used. They included resin cement and respective primer, dedicated to zirconia: Clearfil Ceramic Primer/Panavia F2.0, Monobond Plus/Multilink Automix, AZ - Primer/ResiCem, Z - Prime Plus/Duo-Link. In each group the protocol of cementation was as follows: application of primer to the zirconia surface and application of the respective resin cement in cylindric mold (dimensions: 3.0 mm height and 3.0 mm diameter). Then, the shear bond strength was evaluated and the failure type was assessed in lupes (×2.5 magnification), also random specimens under SEM. The Wilcoxon test was used to analyze the data, the level of significance was α = 0.05. Finally, the known chemical composition of each primer was analysed in reference to probable chemical bonds, which may occure between primers and zirconia. The mean shear bond strength between resin cements and zirconia was the highest for Z-Prime Plus/Duo-Link (8.24 ± 3,21 MPa) and lowest for Clearfil Ceramic Primer/Panavia F 2.0 (4.60 ± 2.21 MPa). The analysis revealed significant difference between all groups, except pair Clearfil Ceramic Primer/Panavia F 2.0 and AZ-Primer/ResiCem. The failure type in groups of Clearfil Ceramic Primer/Panavia F 2.0 and AZ-Primer/ResiCem was mainly adhesive, in groups Monobond Plus/ /Multilink Automix and Z-Prime Plus/Duo-Link mainly mixed. The chemical composition of primers affects different bond mechanisms between resin cements and zirconia. The highest shear bond strength of resin cement to zirconia can be obtained for the primer composed of 10-Methacryloyloxydecyl dihydrogen

  1. Host age, social group, and habitat type influence the gut microbiota of wild ring-tailed lemurs (Lemur catta).

    Science.gov (United States)

    Bennett, Genevieve; Malone, Matthew; Sauther, Michelle L; Cuozzo, Frank P; White, Bryan; Nelson, Karen E; Stumpf, Rebecca M; Knight, Rob; Leigh, Steven R; Amato, Katherine R

    2016-08-01

    The gut microbiota contributes to host health by maintaining homeostasis, increasing digestive efficiency, and facilitating the development of the immune system. The composition of the gut microbiota can change dramatically within and between individuals of a species as a result of diet, age, or habitat. Therefore, understanding the factors determining gut microbiota diversity and composition can contribute to our knowledge of host ecology as well as to conservation efforts. Here we use high-throughput sequencing to describe variation in the gut microbiota of the endangered ring-tailed lemur (Lemur catta) at the Bezà Mahafaly Special Reserve (BMSR) in southwestern Madagascar. Specifically, we measured the diversity and composition of the gut microbiota in relation to social group, age, sex, tooth wear and loss, and habitat disturbance. While we found no significant variation in the diversity of the ring-tailed lemur gut microbiota in response to any variable tested, the taxonomic composition of the gut microbiota was influenced by social group, age, and habitat disturbance. However, effect sizes were small and appear to be driven by the presence or absence of relatively low abundance taxa. These results suggest that habitat disturbance may not impact the lemur gut microbiota as strongly as it impacts the gut microbiota of other primate species, highlighting the importance of distinct host ecological and physiological factors on host-gut microbe relationships. Am. J. Primatol. 78:883-892, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  2. Group composition, intergroup conflicts and use of space in Callithrix penicillata (Geoffroy, 1812 introduced in an urban patch

    Directory of Open Access Journals (Sweden)

    Luciana Zago

    2014-06-01

    Full Text Available The use of space by the Callithix genus can be related to different factors. The objective of this study was to evaluate the influences of different factors on the use of space in C. penicillata introduced in an urban patch. Two groups, called GL and GG, were monitored in two six-month phases at Parque Ecológico do Córrego Grande, Florianópolis, SC, Brazil. Both groups consisted of eight individuals at the beginning of the study. Throughout Phase I some GL individuals disappeared and births occurred among GG, changing the groups’ composition to five and 11 individuals, respectively. In Phase II, GL moved to an inaccessible area preventing sufficient observations. Three GG individuals disappeared and two others were born. Intergroup agonistic behaviors were recorded in all Phase I months, while an abrupt reduction occurred in Phase II. Home range overlaps occurred throughout Phase I. Between Phases I and II, GL left the overlapping area and GG occupied the GL spaces. These changes seem to be related to the increase in GG individuals and their need to access food resources. The use of space dynamics seems to result from spatial limitations, intergroup conflicts, group compositions and availability of food resources.

  3. Interaction between two solid surfaces across PDMS : influence of chain length and end group

    NARCIS (Netherlands)

    Sun, G.X.; Stark, R.; Kappl, M.; Leermakers, F.A.M.; Butt, H.J.

    2005-01-01

    Forces between solid surfaces across polymer melts are poorly understood despite their importance for adhesion and composite materials. Using an atomic force microscope (AFM) this force was measured for poly(dimethyl siloxane) (PDMS) on silicon oxide. The influence of molecular weight (4.0-40 kDa) w

  4. Changes in the sociodemographic composition of the lowest socioeconomic group over time, 1987–2001

    Science.gov (United States)

    Bongers, Frans JM; Deunk, Linelle EN; Schellevis, Francois G; van den Hoogen, Henk JM; van der Zee, Jouke; van den Bosch, Wil JHM

    2007-01-01

    Background When comparing health differences of groups with equal socioeconomic status (SES) over time, the sociodemographic composition of such a SES group is considered to be constant. However, when the periods are sufficiently spaced in time, sociodemographic changes may have occurred. The aim of this study is to examine in which respects the sociodemographic composition of lowest SES group changed between 1987 and 2001. Methods Our data were derived from the first and second Dutch National Survey of General Practice conducted in 1987 and 2001. In 1987 sociodemographic data from all listed patients (N = 334,007) were obtained by filling out a registration form at the practice (response 78.3%, 261,691 persons), in 2001 these data from all listed patients (385,461) were obtained by postal survey (response 76.9%, 296,243 persons). Participants were primarily classified according to their occupation into three SES groups: lowest, middle and highest. Results In comparison with 1987, the lowest SES group decreased in relative size from 34.9% to 29.5%. Within this smaller SES group, the relative contribution of persons with a higher education more than doubled for females and doubled for males. This indicates that the relation between educational level and occupation was less firmly anchored in 2001 than in 1987. The relative proportion of some disadvantaged groups (divorced, unemployed) increased in the lowest SES group, but the size of this effect was smaller than the increase from higher education. Young people (0–24 years) were proportionally less often represented in the lowest SES group. Non-Western immigrants contributed in 2001 proportionally less to the lowest SES group than in 1987, because of an intergenerational upward mobility of the second generation. Conclusion On balance, the changes in the composition did not result in an accumulation of disadvantaged groups in the lowest SES group. On the contrary, the influx of people with higher educational

  5. Changes in the sociodemographic composition of the lowest socioeconomic group over time, 1987–2001

    Directory of Open Access Journals (Sweden)

    van der Zee Jouke

    2007-10-01

    Full Text Available Abstract Background When comparing health differences of groups with equal socioeconomic status (SES over time, the sociodemographic composition of such a SES group is considered to be constant. However, when the periods are sufficiently spaced in time, sociodemographic changes may have occurred. The aim of this study is to examine in which respects the sociodemographic composition of lowest SES group changed between 1987 and 2001. Methods Our data were derived from the first and second Dutch National Survey of General Practice conducted in 1987 and 2001. In 1987 sociodemographic data from all listed patients (N = 334,007 were obtained by filling out a registration form at the practice (response 78.3%, 261,691 persons, in 2001 these data from all listed patients (385,461 were obtained by postal survey (response 76.9%, 296,243 persons. Participants were primarily classified according to their occupation into three SES groups: lowest, middle and highest. Results In comparison with 1987, the lowest SES group decreased in relative size from 34.9% to 29.5%. Within this smaller SES group, the relative contribution of persons with a higher education more than doubled for females and doubled for males. This indicates that the relation between educational level and occupation was less firmly anchored in 2001 than in 1987. The relative proportion of some disadvantaged groups (divorced, unemployed increased in the lowest SES group, but the size of this effect was smaller than the increase from higher education. Young people (0–24 years were proportionally less often represented in the lowest SES group. Non-Western immigrants contributed in 2001 proportionally less to the lowest SES group than in 1987, because of an intergenerational upward mobility of the second generation. Conclusion On balance, the changes in the composition did not result in an accumulation of disadvantaged groups in the lowest SES group. On the contrary, the influx of people with

  6. The Influence of Membership Groups on Selecting Accommodations: the Case of the Residential Tourist

    Directory of Open Access Journals (Sweden)

    Javier Perez-Aranda

    2017-06-01

    Full Text Available An understanding of consumer behavior when choosing property as accommodations improves the use of limited resources such as land and may promote the suitable development of tourism destinations. Knowledge of the factors that influence consumer behavior and that condition the process of purchasing a residential tourism property is useful in managing and designing strategies for segmenting tourism destinations. This study analyzes the influence of membership groups such as social class, culture, and family on choosing the type of property (ownership versus renting or using family or friends’ property and the typology (single- or multifamily that is in demand among residential tourists in the destination. Firstly, we identify which membership groups specifically influence the selection of type of property (social class and family. Then, we identify which groups influence the property typology (social class and people who are traveling and, in addition, those that influence both choices (social class.

  7. Influence of preconsolidation on consolidation quality after stamp forming of C/PEEK composites

    NARCIS (Netherlands)

    Slange, Tjitse; Warnet, Laurent; Grouve, Wouter Johannes Bernardus; Akkerman, Remko; Chinesta, Francisco; Cueto, Elias; Abisset-Chavanne, Emmanuelle

    2016-01-01

    Stamp forming is a rapid manufacturing technology used to shape flat blanks of thermoplastic composite material into three-dimensional components. Currently, expensive autoclave and press consolidation are used to preconsolidate blanks. This study investigates the influence of preconsolidation on

  8. Research into the group composition of tar using the gas liquid chromatography method

    Energy Technology Data Exchange (ETDEWEB)

    Lisin, S.N.; Stepanov, Yu.V.; Lisina, L.A.; Chistyakov, A.N.

    1986-03-01

    This paper first gives a brief review of current methods used for determining chemical composition of tars, then describes experiments using gas liquid chromatography (GLC) to determine the chemical composition of delta/sub 1/, delta/sub 2/, delta, and delta fractions of medium temperature tars obtained during normal solvent processing (isooctane, toluene, quinoline). For delta and delta fractions, a Tsvet-104 chromatograph was used with a flame-ionization detector under the following conditions: column height 3 m, diameter 3 mm, AW-HMDS filler, 0.25-0.36 mm fractions with 5% SE-30, linear column temperature increase from 50-310/sup 0/C, velocity 6 C/min, condenser temperature 350/sup 0/C, velocity of carrier gas (helium) and hydrogen 100 ml/min, air consumption 1.5 l/min. delta/sub 1/ and delta/sub 2/ fractions were determined using a GC-IC chromatograph (manufactured by Shimatsu) under conditions analogous to those given above. Conclusion is that the yield of chromatographable compounds from tar by the GLC method with temperature programming is practically constant for each tar and can be characterized by the delta fraction content and its chemical composition. A method of determining the group composition of tars and the chemical composition of the delta fraction using GLC is proposed. 13 refs.

  9. The influence of FRCs reinforcement on marginal adaptation of CAD/CAM composite resin endocrowns after simulated fatigue loading.

    Science.gov (United States)

    Rocca, Giovanni Tommaso; Saratti, Carlo Massimo; Poncet, Antoine; Feilzer, Albert J; Krejci, Ivo

    2016-05-01

    To evaluate the marginal adaptation of endodontically treated molars restored with CAD/CAM composite resin endocrowns either with or without reinforcement by fibre reinforced composites (FRCs), used in different configurations. 32 human endodontically treated molars were cut 2 mm over the CEJ. Two interproximal boxes were created with the margins located 1 mm below the CEJ (distal box) and 1 mm over the CEJ (mesial box). All specimens were divided in four groups (n = 8). The pulp chamber was filled with: group 1 (control), hybrid resin composite (G-aenial Posterior, GC); group 2, as group 1 but covered by 3 meshes of E-glass fibres (EverStick NET, Stick Tech); group 3, FRC resin (EverX Posterior, GC); group 4, as group 3 but covered by 3 meshes of E-glass fibres. The crowns of all teeth were restored with CAD/CAM composite resin endocrowns (LAVA Ultimate, 3M). All specimens were thermo-mechanically loaded in a computer-controlled chewing machine (600,000 cycles, 1.6 Hz, 49 N and simultaneously 1500 thermo-cycles, 60 s, 5-55 °C). Marginal analysis before and after the loading was carried out on epoxy replicas by SEM at 200× magnification. For all the groups, the percentage values of perfect marginal adaptation after loading were always significantly lower than before loading (p 0.05). Within the limitations of this in vitro study, the use of FRCs to reinforce the pulp chamber of devitalized molars restored with CAD/CAM composite resin restorations did not significantly influenced their marginal quality.

  10. Close friend and group influence on adolescent cigarette smoking and alcohol use.

    Science.gov (United States)

    Urberg, K A; Değirmencioğlu, S M; Pilgrim, C

    1997-09-01

    The relative influence of adolescents closest friends and their friendship group on their cigarette smoking and alcohol use was investigated in a short-term, longitudinal study of 1,028 students in the 6th, 8th, and 10th grades in 2 school systems. The amount of influence over the school year was modest in magnitude and came from the closest friend for initiation of cigarette and alcohol use. Only the friendship group use predicted transition into current cigarette use, whereas only the close friend use predicted transition into current alcohol use. Both group and close friends independently contributed to the prediction of adolescents' drinking to intoxication. No difference in the amount of influence, was found between stable and unstable close friendships or friendship groups; neither grade nor gender of the adolescents related to the amount of influence.

  11. Structural elements of construction of individual and group exercises’ competition compositions in calisthenics

    Directory of Open Access Journals (Sweden)

    Kovalenko Y.O.

    2016-02-01

    Full Text Available Purpose: to analyze content of individual and group exercises’ competition compositions in calisthenics. Material: in the research HEEs’ girl students (n=20, junior sportswomen (n=10, experts (n=30, coaches with 10-40 years’ working experience participated. Results: it was found that temporary indicators permit to assess level of female gymnasts’ readiness for fulfillment of competition compositions’ elements; facilitated rational correlation of body and object’s elements of complexity. Quickness of preparation to elements and directly time of exercise’s fulfillment acquire great importance. In individual and group exercises the most important are distribution of sportswoman’s moving on all site with frequent change of directions. It was established that realization of structural elements facilitates full opening of female gymnast’s artistic image. Conclusions: for building of competition compositions coaches shall fully use indicators of space and time structural elements.

  12. Influence of 26-hydroxycholesterol on the composition and function of gel-filtered platelets

    Energy Technology Data Exchange (ETDEWEB)

    Kou, I.L.; Pikul, J.; Kummerow, F.A. (Univ. of Southern California, Los Angeles (USA))

    1991-04-01

    The influence of 26-hydroxycholesterol (26-OH-CHOL) on the structure and function of gel-filtered rat platelets, as a model membrane, was studied in vitro. Its influence on structure was determined by a fatty acid and a phospholipid analysis of the platelet lipids and on function by the cytoplasmic calcium concentration of the platelets exposed to increasing concentrations of 26-OH-CHOL for various periods of time. The intracellular free calcium (Ca{sup 2}{sup +})i of the gel-filtered rat platelets was monitored by a fluorescent probe (quin 2) after incubation in a 37{degree}C water bath with 1 mM Ca{sup 2}{sup +} and 20 microM quin 2/AM. The presence of 26-OH-CHOL in the incubation media changed both the phospholipid composition and the mixed fatty acid composition in the membrane and increased the intracellular free Ca{sup 2}{sup +} level of the platelets. As the incubation of platelets with cholesterol (CHOL) or esterified 26-OH-CHOL did not increase intracellular Ca{sup 2}{sup +} levels, these results indicate that the hydrophilic free 26-hydroxy group in 26-OH-CHOL may have influenced the enzymes catalyzing the synthesis of the phospholipid in the platelet membrane so as to allow it to become more and more 'leaky' to Ca{sup 2}{sup +}. Such a fundamental change in membrane structure and function may be responsible for the development of atherosclerosis in the intimal layer of the coronary arteries.

  13. Peer Group Counselling and School Influence on Adolescents' Self-Concept

    Science.gov (United States)

    Egbochuku, E. O.; Aihie, N. O.

    2009-01-01

    The study focused on the influence of peer group counselling and school influence on the self-concept of adolescents' in Nigerian secondary schools. Sixty-eight Senior Secondary School II students from three schools--a boys' school, a girls' school and a co-educational school in Benin City participated in the study. A pre-test, post-test control…

  14. Centrality measures in networks based on nodes attributes, long-range interactions and group influence

    CERN Document Server

    Aleskerov, F; Shvydun, S

    2016-01-01

    We propose a new method for assessing agents influence in network structures, which takes into consideration nodes attributes, individual and group influences of nodes, and the intensity of interactions. This approach helps us to identify both explicit and hidden central elements which cannot be detected by classical centrality measures or other indices.

  15. Influence of Mining Thickness on the Rationality of Upward Mining in Coal Seam Group

    OpenAIRE

    2016-01-01

    This study aimed to determine the influence of mining thickness on the rationality of upward mining in coal seam group. Numerical simulation and theoretical analysis were performed to investigate the influence of the mining thicknesses of initial mining seam on the destruction and pressure relief effect of the upper coal seam in a high-gas coal seam group. The mechanical model of the roof failure based on the mining thickness was established by assuming that the gob formed after a...

  16. Influence of group-velocity mismatch on soliton switching in a nonlinear fibre coupler

    Institute of Scientific and Technical Information of China (English)

    李宏; 黄德修; 王东宁

    2003-01-01

    In this work, the influence of group-velocity mismatch on soliton self-routing pulse switching in a nonlinear fibrecoupler is discussed in detail by the use of both variational approach and numerical simulation. The results obtainedshow that the group-velocity mismatch leads to the relative displacement between the two orthogonal polarizationmodes, increase of the critical power, and reduction of the elimination-light ratio. For sub-ps pulse, the influence cannot be neglected.

  17. Influence of nonylphenol on the fatty acids and hydrocarbon composition of aquatic plants

    Directory of Open Access Journals (Sweden)

    І. О. Osinna

    2009-11-01

    Full Text Available Composition of surface lipids of aquatic plants Acorus calamus L., Typha latifolia L. and Carex acuta L. was investigated under the influence of nonylphenol strong solution. Experimental plants showed some significant changes in the surface lipids composition in comparison with a control. Change in the fatty acids composition, decrease of hydrocarbons content and biosynthetical disorder in the elongation processes of some certain components were revealed.

  18. Influence of Synthetic Fibers Angle Orientation on Bending Properties of Composite Plywood

    OpenAIRE

    Mladen Brezović; Jaroslav Kljak; Stjepan Pervan; Alan Antonović

    2010-01-01

    This paper presents the results of research on carbon fiber angle orientation and quantity of carbon fi bers in yarn on bending properties of plywood. For that purpose the specimens have been defined as multilayer composites made from carbon fibers and veneer. Carbon fibers were inserted in the second and third glue line of the composite with angle variation of 15°. Stresses and strain were analyzed in significant layers together with displacement of the whole composite plate. The influence o...

  19. Influence of thermal effect on sugars composition of Mexican Agave syrup

    OpenAIRE

    Muniz-Marquez, D.B.; Contreras, J. C.; Rodriguez, R.; Mussatto, S.I.; Wong-Paz, J.E.; J.A. Teixeira; Aguilar, C.N.

    2015-01-01

    Agave syrup is a fermentable by-product from the Agave industry that is used for pulque production, a typical Mexican fermented beverage. However, to date, the information available on its physicochemical composition is scarce, with this study being one of the first contributions on the subject. Here the influence of thermal treatment at 121ºC/15 min on the physicochemical composition of agave syrup was studied. The chemical composition based on sugar content was evaluated by thin-layer chrom...

  20. Influence of composite resin consistency and placement technique on proximal contact tightness of Class II restorations.

    NARCIS (Netherlands)

    Loomans, B.A.C.; Opdam, N.J.M.; Roeters, F.J.M.; Bronkhorst, E.M.; Plasschaert, A.J.M.

    2006-01-01

    PURPOSE: To investigate the influence of composite resin consistency and placement technique on proximal contact tightness of Class II composite resin restorations. MATERIALS AND METHODS: A manikin model (KaVo Dental) was used with an artificial first molar in which a standardized MO preparation was

  1. Influence of Cure Shrinkage on Process-Induced Stress and Deformation in Thick Thermosetting Composites

    Science.gov (United States)

    1992-07-01

    unidirectional composite micromechanics model The constituent fiber properties (constant), the resin properties and chemical shrinkage (cure dependent...during cure. Changes in the resin properties directly influence the mechanical properties in the composite, and chemical shrinkage represents a...xA (5) The expansion coefficients, otL and or, are based on the micromechanics model utilizing constant fiber properties. cure dependent resin

  2. Influence of surface preparation on fusion bonding of thermoplastic composites

    NARCIS (Netherlands)

    Sacchetti, F.; Grouve, W.J.B.; Warnet, L.L.; Fernandez Villegas, I.

    2015-01-01

    Carbon fibre-reinforced thermoplastic composites laminates (CFRP) meant for fusion bonding have been moulded using different release media. The potential contamination of the laminate surface by the release media and its effect on the mechanical performance of fusion bonded joints was studied. The p

  3. The influence of social comparison and peer group size on risky decision making

    Directory of Open Access Journals (Sweden)

    Dawei Wang

    2016-08-01

    Full Text Available This study explores the influence of different social reference points and different comparison group sizes on risky decision-making. Participants were presented with a scenario describing an exam, and presented with the opportunity of making a risky decision in the context of different information provided about the performance of their peers. We found that behavior was influenced, not only by comparison with peers, but also by the size of the comparison group. Specifically, the larger the reference group, the more polarized the behavior it prompted. In situations describing social loss, participants were led to make riskier decisions after comparing themselves against larger groups, while in situations describing social gain, they become more risk averse. These results indicate that decision making is influenced both by social comparison and the number of people making up the social reference group.

  4. Influence of light energy density on heat generation during photoactivation of dental composites with different dentin and composite thickness

    Directory of Open Access Journals (Sweden)

    Ricardo Danil Guiraldo

    2009-08-01

    Full Text Available OBJECTIVE: The aim of this study was to determine the influence of different energy densities on the heat generated during photoactivation of Filtek Z250 (3M/ESPE and Z100 (3M/ESPE composite resins with different dentin and composite thickness. MATERIAL AND METHODS: The temperature increase was registered with a type-K thermocouple connected to a digital thermometer (Iopetherm 46. A chemically polymerized acrylic resin base was prepared to serve as a guide for the thermocouple and as a support for 0.5-, 1.0-, and 1.5-mm-thick bovine dentin discs. Circular elastomer molds (1.0 mm-height x 3.0-mm diameter or 2.0-mm height x 3.0-mm diameter were adapted on the acrylic resin base to standardize the composite resin thickness. A conventional halogen light-curing unit (XL 2500, 3M/ESPE was used with light intensity of 700 mW/cm². Energy density was calculated by the light intensity applied during a certain time with values of 28 J/cm² for Z100 and 14 J/cm² for Filtek Z250. The temperature change data were subjected to three-way ANOVA and Tukey's test at 5% level. RESULTS: The higher energy density (Z100 promoted greater temperature increase (p<0.05 than the lower energy density (Filtek Z250. For both composites and all composite thicknesses, the lowest dentin thickness (0.5 mm yielded significantly higher (p<0.05 temperature increase than the other two dentin thicknesses. The 1-mm-thick composite resin layer yielded significantly higher (p<0.05 temperature changes for both composites and all dentin thicknesses. CONCLUSIONS: Temperature increase was influenced by higher energy density and dentin/composite thickness.

  5. Influence of light-curing unit systems on shear bond strength and marginal microleakage of composite resin restorations

    Directory of Open Access Journals (Sweden)

    Juliano Fernandes Sassi

    2008-03-01

    Full Text Available The aim of the present study was to evaluate the influence of different photopolymerization (halogen, halogen soft-start and LED systems on shear bond strength (SBS and marginal microleakage of composite resin restorations. Forty Class V cavities (enamel and dentin margins were prepared for microleakage assessment, and 160 enamel and dentin fragments were prepared for the SBS test, and divided into 4 groups. Kruskal-Wallis and Wilcoxon tests showed statistically significant difference in microleakage between the margins (p 0.05 neither between substrates nor among groups. It was concluded that Soft-Start technique with high intensity end-light influenced negatively the cervical marginal sealing, but the light-curing systems did not influence adhesion.

  6. Bio-polymer coatings on neural probe surfaces: Influence of the initial sample composition

    Energy Technology Data Exchange (ETDEWEB)

    Chow, Winnie W.Y. [Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala (Sweden); Herwik, Stanislav; Ruther, Patrick [Department of Microsystems Engineering (IMTEK), University of Freiburg (Germany); Goethelid, Emmanuelle [Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala (Sweden); Oscarsson, Sven, E-mail: sven@svenoscarsson.com [Department of Organic Chemistry, Stockholm University, Arrhenius Laboratory, SE-106 91 Stockholm (Sweden)

    2012-08-01

    This paper presents the results of the study of hyaluronic acid (HyA) coating on two structural materials, silicon oxide (dielectric) surface and platinum (Pt) surface used for fabrication of probes developed for neurological investigations in the framework of the EU-project NeuroProbes. The silicon-based neural probes consist of multiple Pt electrodes on the probe shafts for neural recording applications. HyA coatings were proposed to apply on the probe surfaces to enhance the biocompatibility. This study aims at understanding the influence of the initial composition of the probe surface on the structure and morphology of HyA coating. HyA was chemically functionalized by SS-pyridin using (N-Succinimidyl 3-[2-pyridyldithio]-propionate) (SPDP) and was immobilized on the surfaces via a covalent bond. The dielectric and Pt surfaces were derivatized by use of (3-mercaptopropyl) methyldimethoxysilane (MPMDMS). The silanol groups in MPMDMS bind to the dielectric surface, leaving the thiol groups at the uppermost surface and the thiol groups then bind covalently to the functionalized HyA. On the Pt surface, it is the thiol group which binds on the Pt surface. The coated surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). A well-defined HyA layer was observed on both dielectric and Pt surfaces. The coating of two molecular weights (340 kDa and 1.3 MDa) of HyA was examined. The influence of the silanized layer on the HyA coating was also investigated.

  7. Influence of enamel composite thickness on value, chroma and translucency of a high and a nonhigh refractive index resin composite.

    Science.gov (United States)

    Ferraris, Federico; Diamantopoulou, Sofia; Acunzo, Raffaele; Alcidi, Renato

    2014-01-01

    To evaluate the influence of thickness on the optical properties of two enamel shade composites, one with a high refractive index and one traditional. A medium value enamel shade was selected from the resin composites Enamel Plus HRi (UE2) and Enamel Plus HFO (GE2). Enamel Plus HRi is a high refractive index composite. Samples were fabricated in five different thicknesses: 0.3, 0.5, 1, 1.5 and 2 mm. Three specimens per material and thickness were fabricated. Three measurements per sample, over white, black and dentin composite background were generated with a spectrophotometer (Spectroshade Micro, MHT). Value, chroma, translucency and color differences (ΔE) of the specimens were calculated. RESULTS were analyzed by the Pearson correlation test, ANOVA and a post-hoc Tukey test. Increasing the thickness of the enamel layers decreased the translucency and the chroma of the substrate for both materials tested. For HRi the increase of the thickness resulted in an increase of the value, whereas for HFO it resulted in a reduction of the value. The two composites showed a significant difference in value for each thickness, but not in translucency and chroma. Color difference between them was perceptible in layers equal or higher than 0.5 mm. The high refractive index enamel (HRi) composite exhibits different optical behavior compared to the traditional one (HFO). HRi enamel composite behaves more like natural enamel as by increasing the thickness of the enamel layer, the value also increases.

  8. Empirical study of the influence of social groups in evacuation scenarios

    CERN Document Server

    von Krüchten, Cornelia; Svachiy, Anton; Wohak, Oliver; Schadschneider, Andreas

    2016-01-01

    The effects of social groups on pedestrian dynamics, especially in evacuation scenarios, have attracted some interest recently. However, due to the lack of reliable empirical data, most of the studies focussed on modelling aspects. It was shown that social groups can have a considerable effect, e.g. on evacuation times. In order to test the model predictions we have performed laboratory experiments of evacuations with different types and sizes of the social groups. The experiments have been performed with pupils of different ages. Parameters that have been considered are (1) group size, (2) strength of intra-group interactions, and (3) composition of the groups (young adults, children, and mixtures). For all the experiments high-quality trajectories for all participants have been obtained using the PeTrack software. This allows for a detailed analysis of the group effects. One surprising observation is a decrease of the evacuation time with increasing group size.

  9. Influence of Breed, Parity and Food Intake on Chemical Composition of First Colostrum in Cow

    Directory of Open Access Journals (Sweden)

    Simona Zarcula

    2010-05-01

    Full Text Available The aim of this research was to establish the influence of breed, parity and food intake on chemical composition of first colostrum. We observed that fat, proteins, lactose and dry matter were higher in cows from second and third lactation compared to those in fourth lactation. Cow's breed also influenced the colostrum composition, superior quality being obtained in case of Romanian White and Black comparing Holstein Friesian cows. The unbalanced energo-proteic ratio had a negative impact on chemical composition of first colostrum.

  10. The Influence of Fiber Type and Conformation on the Damping Property of FRP Composite

    Institute of Scientific and Technical Information of China (English)

    WANG Xiang; CHEN Wei; WANG Jun; LIU Hanxing

    2012-01-01

    In order to get a fiber reinforced plastic(FRP) composite with good damping property as well as good mechanical properties,different types of reinforcing materials were used to reinforcing a damping resin.The influence of fiber types and conformation on the damping property of the composite are tested.Compared to the glass fiber(GF),carbon fiber(CF) can improve the damping factor of the composites; the highest tanδ value is 0.827 while the Tg is 22.5 ℃.The style of the fibers also influences the damping factors of the composite.The composite reinforced with mat has higher loss factors than that composite reinforced with clothe for the reason that the former has the ability to deform and the composite has higher resin content.The loss factor of GF mat reinforced composite is 0.704 while the T is 27 ℃.Both composite has good damping properties and can be used as the damping layer of the structural damping composite.

  11. Influence of a prophylaxis paste on surface roughness of different composites, porcelain, enamel and dentin surfaces

    OpenAIRE

    2012-01-01

    Objective: To investigate the effect of a prophylaxis paste on surface roughness of different composites, enamel, dentin and porcelain surfaces. Methods: Three different composites (FiltekZ250/Group1, Filtek Supreme XT/Group2, Premise/Group3), enamel/Group4, dentin/Group5 and porcelain/Group6 samples were used in this study. All specimens were prepared flat by SiC discs and polished with a diamond polishing paste. The surface roughness measurements were determined with a profilometer after po...

  12. Influence of Emulsification of Composite Collector on Rutile Flotation

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The emulsifiable conditions of composite collector (FP-2) in industry are systematically researched in the paper. It is found that tpyes of the emulsifiers, emulsification temperature, the mixed proportion of FP-2 to emulsifier are the important parameters affecting emulsification effect and rutile flotation targets. When the proportion of FP-2 to emulsifier (E-4) is 100, by means of emulsification of mechanical stirring, the rutile flotation recovery is 85.6% and the grade is 75.3%, which approach the flotation targets of FP-2 used as collector by ultrasonic emulsification unit. The favorable conditions are set up for FP-2 in industry application. By means of XPS measurement,the chemical interaction of composite collector with rutile is found.

  13. How Muscle Structure and Composition Influence Meat and Flesh Quality

    Directory of Open Access Journals (Sweden)

    Anne Listrat

    2016-01-01

    Full Text Available Skeletal muscle consists of several tissues, such as muscle fibers and connective and adipose tissues. This review aims to describe the features of these various muscle components and their relationships with the technological, nutritional, and sensory properties of meat/flesh from different livestock and fish species. Thus, the contractile and metabolic types, size and number of muscle fibers, the content, composition and distribution of the connective tissue, and the content and lipid composition of intramuscular fat play a role in the determination of meat/flesh appearance, color, tenderness, juiciness, flavor, and technological value. Interestingly, the biochemical and structural characteristics of muscle fibers, intramuscular connective tissue, and intramuscular fat appear to play independent role, which suggests that the properties of these various muscle components can be independently modulated by genetics or environmental factors to achieve production efficiency and improve meat/flesh quality.

  14. Interest groups at transnational negotiation conferences: goals, strategies, interactions, and influence

    NARCIS (Netherlands)

    Hanegraaff, M.

    2015-01-01

    Interest groups partake in transnational negotiation conferences en masse. This is surprising given that the chances for influencing policymaking at these venues appear to be slim while the costs of participation are high. This amounts to an interesting question: why do so many interest groups atten

  15. Interest groups at transnational negotiation conferences: goals, strategies, interactions, and influence

    NARCIS (Netherlands)

    Hanegraaff, M.

    2015-01-01

    Interest groups partake in transnational negotiation conferences en masse. This is surprising given that the chances for influencing policymaking at these venues appear to be slim while the costs of participation are high. This amounts to an interesting question: why do so many interest groups

  16. The influence of friendship groups and media on eating behavior and physical activity in adolescents

    NARCIS (Netherlands)

    MD E.J.M. Wouters; Prof Rinie Geenen

    2012-01-01

    The global epidemic of overweight and obesity results from individual factors and from meso- and macro environmental factors. Adolescents are especially vulnerable to unhealthy changes in life style. One major influence on health behavior in this age group is represented by friends in peer groups.

  17. The Influence of Primitive Subgroups on the Structure of Finite Groups

    Institute of Scientific and Technical Information of China (English)

    Liu Yu-feng; Du Xian-kun(Communicated)

    2013-01-01

    A subgroup H of a group G is said to be primitive if it is a proper subgroup of the intersection of all subgroups of G containing H as its proper subgroup. The purpose of this note is to go further into the influence of primitive subgroups on the structure of finite groups. Some new results are obtained.

  18. The influence of friendship groups and media on eating behavior and physical activity in adolescents

    NARCIS (Netherlands)

    Wouters, Eveline; Geenen, Rinie

    2012-01-01

    The global epidemic of overweight and obesity results from individual factors and from meso- and macro environmental factors. Adolescents are especially vulnerable to unhealthy changes in life style. One major influence on health behavior in this age group is represented by friends in peer groups. Y

  19. INFLUENCE OF PIEZOELECTRIC TRANSDUCER TO GLASS FIBER REINFORCED COMPOSITE STIFFNESS

    Directory of Open Access Journals (Sweden)

    Witold Rządkowski

    2015-08-01

    Full Text Available The main goal was to determine if transducers based on piezoelectric materials are suitable for strain calculations in thin GFRP specimens. Numerous experimental studies, both physical and numerical, performed by the authors, have shown that there is a huge influence of bonded piezoelectric transducer on the overall stiffness of the measured object. The paper presents tensile test performed on strength machine with Digital Image Correlation strain and deflection observations. Test were compared with FEM models for detailed investigation. The main conclusion is piezoelectric transducers has huge influence on local stiffness of measured object. That is critical especially when they are used as strain sensors, when presence of sensor is influencing to measured results.

  20. Dating Violence and Sexual Assault Prevention with African American Middle Schoolers: Does Group Gender Composition Impact Dating Violence Attitudes?

    Science.gov (United States)

    Black, Beverly M.; Weisz, Arlene N.; Jayasundara, Dheeshana S.

    2012-01-01

    A dating violence and sexual assault prevention program was presented to 396, predominately African American, middle schoolers in two inner city schools in the United States. In one school the program was offered with a same-gender group composition; in the other school, the same program was offered with mixed-gender group composition. A…

  1. Dating Violence and Sexual Assault Prevention with African American Middle Schoolers: Does Group Gender Composition Impact Dating Violence Attitudes?

    Science.gov (United States)

    Black, Beverly M.; Weisz, Arlene N.; Jayasundara, Dheeshana S.

    2012-01-01

    A dating violence and sexual assault prevention program was presented to 396, predominately African American, middle schoolers in two inner city schools in the United States. In one school the program was offered with a same-gender group composition; in the other school, the same program was offered with mixed-gender group composition. A…

  2. Influence of the distance of the curing light source and composite shade on hardness of two composites

    OpenAIRE

    Thaís Thomé; Washington Steagall Jr.; Arlene Tachibana; Sheila Regina Maia Braga; Miriam Lacalle Turbino

    2007-01-01

    This study evaluated the influence of curing tip distance, shade and filler particle size on Vickers microhardness (VHN) of composite resins. Two composites were tested: Filtek Z250 microhybrid (3M ESPE; shades A1 and A3.5) and Filtek Supreme nanofilled (3M ESPE; shades A1B and A3.5B). For each resin, 42 specimens (5 mm in diameter and 2 mm height) were prepared being 21 for each shade. The specimens were exposed using a 20-second exposure to a quartz-tungsten-halogen light source with an irr...

  3. Improving the use of research evidence in guideline development: 3. Group composition and consultation process

    Directory of Open Access Journals (Sweden)

    Oxman Andrew D

    2006-11-01

    Full Text Available Abstract Background The World Health Organization (WHO, like many other organisations around the world, has recognised the need to use more rigorous processes to ensure that health care recommendations are informed by the best available research evidence. This is the third of a series of 16 reviews that have been prepared as background for advice from the WHO Advisory Committee on Health Research to WHO on how to achieve this. Objective In this review we address the composition of guideline development groups and consultation processes during guideline development. Methods We searched PubMed and three databases of methodological studies for existing systematic reviews and relevant methodological research. We did not conduct systematic reviews ourselves. Our conclusions are based on the available evidence, consideration of what WHO and other organisations are doing and logical arguments. Key questions and answers What should be the composition of a WHO-panel that is set up to develop recommendations? The existing empirical evidence suggests that panel composition has an impact on the content of the recommendations that are made. There is limited research evidence to guide the exact composition of a panel. Based on logical arguments and the experience of other organisations we recommend the following: • Groups that develop guidelines or recommendations should be broadly composed and include important stakeholders such as consumers, health professionals that work within the relevant area, and managers or policy makers. • Groups should include or have access to individuals with the necessary technical skills, including information retrieval, systematic reviewing, health economics, group facilitation, project management, writing and editing. • Groups should include or have access to content experts. • To work well a group needs an effective leader, capable of guiding the group in terms of the task and process, and capable of facilitating

  4. Fatty acid composition of breast milk from three racial groups from Penang, Malaysia.

    Science.gov (United States)

    Kneebone, G M; Kneebone, R; Gibson, R A

    1985-04-01

    The fatty acid composition of samples of breast milk obtained from 51 mothers (26 Malay, 15 Chinese, 10 Indian) residing in Penang, Malaysia was determined by gas chromatography. Despite living in close physical proximity the mothers from the three racial groups showed distinct cultural differences in dietary intake. These differences were reflected in differences in the fatty acid composition of breast milk samples. The milk of Chinese mothers was generally less saturated (41%) than that of Malay and Indian mothers (52 and 50% respectively). The milk of Chinese mothers was also richer in linoleic acid (17%) than that of Malay and Indian mothers (9% and 11% respectively). Overall the level of individual fatty acids fell within the range of values reported for Western mothers on well nourished diets and pointed to breast milk of high standard despite large variations in the diet of Malaysian mothers.

  5. Thickness of CAD-CAM composite resin overlays influences fatigue resistance of endodontically treated premolars.

    Science.gov (United States)

    Magne, Pascal; Knezevic, Alena

    2009-10-01

    Evaluate the influence of composite resin CAD-CAM restoration thickness on the in vitro fatigue resistance and failure mode of overlay-type restoration in endodontically treated premolars. Thirty extracted premolars received root canal treatment followed by a standardized tooth preparation (1.5-, 2.5- or 3.5-mm cusp reduction, proximal gingival margins located 1.5mm below the CEJ, glass-ionomer base and immediately sealed dentin with Optibond FL). Restorations were milled using Cerec3 and FiltekMZ100 composite blocks. The intaglio surfaces of the overlays were sandblasted and silanated. Tooth preparations were sandblasted and etched before insertion of the restoration. All restorations were luted with Optibond FL and preheated FiltekZ100. A closed-loop servohydraulic unit was used for simulating cyclic isometric chewing at 5 Hz, starting with a load of 200 N (5000 cycles), followed by stages of 400, 600, 800, 1000, 1200 and 1400 N at a maximum of 30,000 cycles each. All samples were loaded until fracture or to a maximum of 185,000 cycles. Groups were compared using the Kaplan-Meier survival curves. None of the restored premolars with the 1.5-mm cusp overlap restoration withstood all 185,000 loading cycles. With 2.5- and 3.5-mm cusp overlap, the survival rate was 30% and 40%, respectively. The rate of fracture below the CEJ was 60%, 60% and 30% for 1.5, 2.5 and 3.5 mm of cusp overlap, respectively. Survival of restored premolars with 2.5- and 3.5-mm cusp coverage was not significantly different (p=.23). Thick FiltekMZ100 composite resin onlays showed higher fatigue resistance than thin ones and may be associated with fractures that are less subgingival.

  6. Composition Influence on Pulmonary Delivery of Rifampicin Liposomes

    Directory of Open Access Journals (Sweden)

    Maria Letizia Manca

    2012-11-01

    Full Text Available The effects of lipid concentration and composition on the physicochemical properties, aerosol performance and in vitro toxicity activity of several rifampicin-loaded liposomes were investigated. To this purpose, six liposome formulations containing different amounts of soy phosphatidylcholine and hydrogenated soy phosphatidylcholine, with and without cholesterol and oleic acid, were prepared and fully characterized. Uni- or oligo-lamellar, small (~100 nm, negatively charged (~60 mV vesicles were obtained. Lipid composition affected aerosol delivery features of liposomal rifampicin; in particular, the highest phospholipid concentration led to a better packing of the vesicular bilayers with a consequent higher nebulization stability. The retention of drug in nebulized vesicles (NER% was higher for oleic acid containing vesicles (55% ± 1.4% than for the other samples (~47%. A549 cells were used to evaluate intracellular drug uptake and in vitro toxicity activity of rifampicin-loaded liposomes in comparison with the free drug. Cell toxicity was more evident when oleic acid containing liposomes were used.

  7. Fire Influences on Atmospheric Composition, Air Quality, and Climate

    Science.gov (United States)

    Voulgarakis, Apostolos; Field, Robert D.

    2015-01-01

    Fires impact atmospheric composition through their emissions, which range from long-lived gases to short-lived gases and aerosols. Effects are typically larger in the tropics and boreal regions but can also be substantial in highly populated areas in the northern mid-latitudes. In all regions, fire can impact air quality and health. Similarly, its effect on large-scale atmospheric processes, including regional and global atmospheric chemistry and climate forcing, can be substantial, but this remains largely unexplored. The impacts are primarily realised in the boundary layer and lower free troposphere but can also be noticeable in upper troposphere/lower stratosphere (UT/LS) region, for the most intense fires. In this review, we summarise the recent literature on findings related to fire impact on atmospheric composition, air quality and climate. We explore both observational and modelling approaches and present information on key regions and on the globe as a whole. We also discuss the current and future directions in this area of research, focusing on the major advances in emission estimates, the emerging efforts to include fire as a component in Earth system modelling and the use of modelling to assess health impacts of fire emissions.

  8. Influence of nanometric silicon carbide on phenolic resin composites properties

    Indian Academy of Sciences (India)

    GEORGE PELIN; CRISTINA-ELISABETA PELIN; ADRIANA STEFAN; ION DINC\\u{A}; ANTON FICAI; ECATERINA ANDRONESCU; ROXANA TRUSC\\u{A}

    2016-06-01

    This paper presents a preliminary study on obtaining and characterization of phenolic resin-based composites modified with nanometric silicon carbide. The nanocomposites were prepared by incorporating nanometric silicon carbide (nSiC) into phenolic resin at 0.5, 1 and 2 wt% contents using ultrasonication to ensure uniform dispersion of the nanopowder, followed by heat curing of the phenolic-based materials at controlled temperature profile up to 120$^{\\circ}$C. The obtained nanocomposites were characterized by FTIR spectroscopy and scanning electron microscopy analysis and evaluated in terms of mechanical, tribological and thermal stability under load. The results highlight the positive effect of the nanometric silicon carbide addition in phenolic resin on mechanical, thermo-mechanical and tribological performance, improving their strength, stiffness and abrasive properties. The best results were obtained for 1 wt% nSiC, proving that this value is the optimum nanometric silicon carbide content. The results indicate that these materials could be effectively used to obtain ablative or carbon–carbon composites in future studies.

  9. Fire Influences on Atmospheric Composition, Air Quality, and Climate

    Science.gov (United States)

    Voulgarakis, Apostolos; Field, Robert D.

    2015-01-01

    Fires impact atmospheric composition through their emissions, which range from long-lived gases to short-lived gases and aerosols. Effects are typically larger in the tropics and boreal regions but can also be substantial in highly populated areas in the northern mid-latitudes. In all regions, fire can impact air quality and health. Similarly, its effect on large-scale atmospheric processes, including regional and global atmospheric chemistry and climate forcing, can be substantial, but this remains largely unexplored. The impacts are primarily realised in the boundary layer and lower free troposphere but can also be noticeable in upper troposphere/lower stratosphere (UT/LS) region, for the most intense fires. In this review, we summarise the recent literature on findings related to fire impact on atmospheric composition, air quality and climate. We explore both observational and modelling approaches and present information on key regions and on the globe as a whole. We also discuss the current and future directions in this area of research, focusing on the major advances in emission estimates, the emerging efforts to include fire as a component in Earth system modelling and the use of modelling to assess health impacts of fire emissions.

  10. Influence of substrate composition on the formation of phytic acid conversion coatings

    Energy Technology Data Exchange (ETDEWEB)

    Cui, X.; Wang, F. [School of Material Science and Chemical Engineering, Harbin Engineering University, Harbin (China); State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang (China); Jin, G.; Liu, E.; Ding, M.; Li, Q. [School of Material Science and Chemical Engineering, Harbin Engineering University, Harbin (China)

    2012-03-15

    In this paper, the formation and corrosion resistance of the phytic acid conversion coatings on Mg, Al, and AZ91D magnesium alloy were contrastively investigated using scanning electronic microscopy (SEM), Auger electron spectroscopy (AES), Fourier transform infrared spectroscopy (FTIR), electronic probe microscopic analyzer (EPMA), electronic balance, and electrochemical methods. The influence of phytic acid conversion coating as a middle layer on the properties of the paint on magnesium alloys was also investigated. The results show that the formation process of the conversion coatings is evidently influenced by the compositions of the substrate. The coating on pure aluminum is thinner and compacter than that on pure magnesium and the coating formed on {alpha} phase in AZ91D magnesium alloy is thinner but denser than that on {beta} phase. The phytic acid conversion coatings formed on Mg, Al, and AZ91D magnesium alloy can all increase their corrosion resistance. The active functional groups of hydroxyl and phosphate radical are rich in the conversion coatings, which can improve the bonding between the organic paint and magnesium alloy and then improve their corrosion resistance. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Functional group composition of ambient and source organic aerosols determined by tandem mass spectrometry

    Directory of Open Access Journals (Sweden)

    J. Dron

    2010-04-01

    Full Text Available The functional group composition of various organic aerosols (OA is being investigated using a recently developed analytical approach based on atmospheric pressure chemical ionisation-tandem mass spectrometry (APCI-MS/MS. The determinations of the three functional groups' contents are performed quantitatively by neutral loss (carboxylic and carbonyl groups and precursor ion (nitro groups scanning modes of a tandem mass spectrometer. Major organic aerosol sources are studied: vehicular emission and wood combustion for primary aerosol sources; and a secondary organic aerosol (SOA produced through photo-oxidation of o-xylene. The results reveal significant differences in the functional group contents of these source aerosols. The laboratory generated SOA is dominated by carbonyls while carboxylics are preponderate in the wood combustion particles. On the other hand, vehicular emissions are characterised by a strong nitro content. The total amount of the three functional groups accounted for 1.7% (vehicular to 13.5% (o-xylene photo-oxidation of the organic carbon. The diagnostic functional group ratios are then used to tentatively differentiate sources of particles collected in an urban background environment located in an Alpine valley (Chamonix, France during a strong winter pollution event. The three functional groups under study account for a total functionalisation rate of 2.2 to 3.8% of the organic carbon in this ambient aerosol, which is also dominated by carboxylic moieties. In this particular case study of a deep alpine valley during winter, we show that the nitro- and carbonyl-to-carboxylic diagnostic ratios can be a useful tool to distinguish the sources. In these conditions, the total OA concentrations are highly dominated by wood combustion OA. This result is confirmed by an organic markers source apportionment approach which assesses a wood burning organic carbon contribution of about 60%. Finally, examples of functional group mass

  12. Plant functional group composition modifies the effects of precipitation change on grassland ecosystem function.

    Science.gov (United States)

    Fry, Ellen L; Manning, Pete; Allen, David G P; Hurst, Alex; Everwand, Georg; Rimmler, Martin; Power, Sally A

    2013-01-01

    Temperate grassland ecosystems face a future of precipitation change, which can alter community composition and ecosystem functions through reduced soil moisture and waterlogging. There is evidence that functionally diverse plant communities contain a wider range of water use and resource capture strategies, resulting in greater resistance of ecosystem function to precipitation change. To investigate this interaction between composition and precipitation change we performed a field experiment for three years in successional grassland in southern England. This consisted of two treatments. The first, precipitation change, simulated end of century predictions, and consisted of a summer drought phase alongside winter rainfall addition. The second, functional group identity, divided the plant community into three groups based on their functional traits- broadly described as perennials, caespitose grasses and annuals- and removed these groups in a factorial design. Ecosystem functions related to C, N and water cycling were measured regularly. Effects of functional groupidentity were apparent, with the dominant trend being that process rates were higher under control conditions where a range of perennial species were present. E.g. litter decomposition rates were significantly higher in plots containing several perennial species, the group with the highest average leaf N content. Process rates were also very strongly affected by the precipitation change treatmentwhen perennial plant species were dominant, but not where the community contained a high abundance of annual species and caespitose grasses. This contrasting response could be attributable to differing rooting patterns (shallower structures under annual plants, and deeper roots under perennials) and faster nutrient uptake in annuals compared to perennials. Our results indicate that precipitation change will have a smaller effect on key process rates in grasslandscontaining a range of perennial and annual species

  13. Plant functional group composition modifies the effects of precipitation change on grassland ecosystem function.

    Directory of Open Access Journals (Sweden)

    Ellen L Fry

    Full Text Available Temperate grassland ecosystems face a future of precipitation change, which can alter community composition and ecosystem functions through reduced soil moisture and waterlogging. There is evidence that functionally diverse plant communities contain a wider range of water use and resource capture strategies, resulting in greater resistance of ecosystem function to precipitation change. To investigate this interaction between composition and precipitation change we performed a field experiment for three years in successional grassland in southern England. This consisted of two treatments. The first, precipitation change, simulated end of century predictions, and consisted of a summer drought phase alongside winter rainfall addition. The second, functional group identity, divided the plant community into three groups based on their functional traits- broadly described as perennials, caespitose grasses and annuals- and removed these groups in a factorial design. Ecosystem functions related to C, N and water cycling were measured regularly. Effects of functional groupidentity were apparent, with the dominant trend being that process rates were higher under control conditions where a range of perennial species were present. E.g. litter decomposition rates were significantly higher in plots containing several perennial species, the group with the highest average leaf N content. Process rates were also very strongly affected by the precipitation change treatmentwhen perennial plant species were dominant, but not where the community contained a high abundance of annual species and caespitose grasses. This contrasting response could be attributable to differing rooting patterns (shallower structures under annual plants, and deeper roots under perennials and faster nutrient uptake in annuals compared to perennials. Our results indicate that precipitation change will have a smaller effect on key process rates in grasslandscontaining a range of perennial

  14. Influence of porosity on thermophysical properties of a composite

    Energy Technology Data Exchange (ETDEWEB)

    Grishaeva, N. Yu., E-mail: anohina@mail2000.ru; Ljukshin, B. A., E-mail: lba2008@yandex.ru; Bochkareva, S. A., E-mail: svetlanab7@yandex.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Tomsk State University of Control Systems and Radioelectronics, Tomsk, 634050 (Russian Federation); Strukov, Yu. S., E-mail: regent@yandex.ru [Tomsk State University of Control Systems and Radioelectronics, Tomsk, 634050 (Russian Federation)

    2015-10-27

    In many modern information systems, the heat generated during the operation of electronic devices is usually dissipated by heat-conductive pads between the casing of the respective equipment and a massive base (platform). For newly developed pads, the promising materials are composites on the basis of various types of silicone rubber. At the same time, during the production of the pads without a vacuum setup, the material can contain air bubbles, which causes the porosity potentially negative for the thermal properties of the material. This work studies the thermal conductivity depending on the degree of silicone matrix filling by copper particles, introduced to improve thermal conductivity, and by air bubbles that are considered as reinforcing inclusions.

  15. The style of group working and its influence on team performance

    Directory of Open Access Journals (Sweden)

    Robson Luiz Montanari

    2012-08-01

    Full Text Available This case study aims to evaluate the influence of the style of group working in the teams’ performance in a midsize services company in Parana State. For this purpose an exploratory interview was originally performed. Then the questionnaires were applied: Working Group Style, proposed by Parker (1994 and Evaluation of a Success Team, proposed by Chang (1999. Besides the questionnaires, non-participant observations were made that intended to register items which interest the research objectives. Finally, the data analysis was carried out, making intersection with the interviews and the non-participant observations. The results identified some influences of the group working styles in the performance of teams. The different behaviors determined the degree of influence which help or not the performance of teams in this study. Two result matrices were found. The first with a relatively uniform distribution of styles, but presenting lower performance; the second showed a predominant contributor style and a higher performance of teams.

  16. Factors influencing trace element composition in human teeth

    Energy Technology Data Exchange (ETDEWEB)

    Tandon, L. [Los Alamos National Lab., NM (United States); Iyengar, G.V. [Biomineral Sciences International, Inc., Bethesda, MD (United States)

    1997-12-01

    The authors recently compiled and reviewed the literature published in or after 1978 for 45 major, minor, and trace elements in human teeth as a part of an International Atomic Energy Agency (IAEA) study. The purpose of this paper is to discuss the various factors that influence the concentration levels of certain trace elements in human teeth. The sampling practices and analytical techniques that are applicable for trace element analysis are also discussed. It is also our intention to identify reference range of values, where data permit such conclusions. The scrutiny was designed to identify only the healthy permanent teeth, and values from teeth with fillings, caries, or periodontal diseases were eliminated.

  17. Influence Of Nutritional Status On Breast Milk Composition

    Directory of Open Access Journals (Sweden)

    Natu Maya

    1985-01-01

    Full Text Available Total and fractional protein analysis of serum and breast milk in hundred lactating mothers was done after them into two groups according to their nutritional status. Apparently there was no correlation between maternal nutrition and total breast milk proteins. In comparison with Western norms, reversal of albumin globulin ratio both in serum and milk was seen.

  18. The Role of Family Influences on Adolescent Smoking in Different Racial/Ethnic Groups

    Science.gov (United States)

    Xiao, Yang; Gordon, Judith S.; Khoury, Jane C.

    2012-01-01

    Introduction: Although differing levels of family influences may explain some of the varying racial/ethnic trends in adolescent smoking behavior, clarification of which influences are protective against smoking may aid in the development of future ethnic-specific smoking prevention interventions. We sought to identify and compare the association of family influences on adolescent smoking among Black, Hispanic, and White adolescents in a cross-sectional national sample. Methods: Data from 6,426 parent–child dyads from Round 1 of the National Survey of Parents and Youth were analyzed. The association of family influences with ever-smokers and recent smokers was evaluated. Multinomial logistic regression using SUDAAN software was used. Results: While all measures of family influences except for parent–adolescent activities and intention to monitor were significantly protective against recent smoking and ever smoking among Whites, ethnic-specific family influence predictors of smoking were found in Blacks and Hispanics. Higher parental monitoring, higher intention to monitor, and higher connectedness were protective among Hispanics, while higher parental punishment and favorable attitude toward monitoring were protective against smoking among Blacks. For family influences significantly associated with protection against smoking, consistently greater protection was afforded against recent smoking than against ever smoking. Conclusions: Higher levels of family influences are protective against smoking among all racial/ethnic groups. There are consistencies in family influences on youth smoking; however, there may be specific family influences that should be differentially emphasized within racial/ethnic groups in order to protect against smoking behavior. Our results offer insight for designing strategies for preventing smoking in youth of different racial/ethnic backgrounds. PMID:22180584

  19. Eating in groups: Do multiple social influences affect intake in a fast-food restaurant?

    Science.gov (United States)

    Brindal, Emily; Wilson, Carlene; Mohr, Philip; Wittert, Gary

    2015-05-01

    This study investigated multiple social influences to determine whether they affect amount eaten at a fast-food environment. Using observational methods, data on meal duration, foods eaten and personal characteristics were collected for 157 McDonald's patrons. Analysis of covariance revealed that female diners ate less kilojoules when eating in mixed- versus same-sex groups (adjusted difference = 967 kJ, p groups compared to pairs (adjusted difference = 1067 kJ, p = .019). Influences to increase and restrict the amount eaten can operate simultaneously in an eating environment with gender a critical factor for consideration.

  20. Influence of pre-Mississippian paleogeology on Carboniferous Lisburne Group, Arctic National Wildlife refuge, northeastern Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Watts, K.F.; Carlson, R.; Imm, T.; Gruzlovic, P.; Hanks, C.

    1988-02-01

    The Carboniferous Lisburne Group of northern Alaska formed an extensive carbonate platform, which was later deformed as part of the Brooks Range fold and thrust belt. In the northeast, the Lisburne Group is parautochthonous and analogous to that at Prudhoe Bay. The Lisburne's paleogeography and facies relationships pertain to assessment of the petroleum potential of the Arctic National Wildlife Refuge (ANWR). The Franklinian paleogeology, unconformably underlying the Ellesmerian sequence, has influenced sedimentation patterns in the Lisburne Group. The transgressive Endicott Group (Kekiktuk Conglomerate and Kayak, Shale) and Lisburne Group thin northward over Franklinian basement highs. In the Sadlerochit Mountains, the Katakturuk Dolomite formed a paleotopographic high over which the Endicott Group inched out and the Lisburne Group thinned. Shallow-marine oolitic grainstone developed in the cyclic Pennsylvanian Wahoo Limestone.

  1. Influence of carbon nanoparticles on the properties of screen printed polymer composites

    Science.gov (United States)

    Jakubowska, Małgorzata; Janeczek, Kamil; MłoŻniak, Anna; Kozioł, GraŻyna; Araźna, Aneta

    2013-07-01

    Further development of printed electronics requires investigations of new polymer composites which can be coated on flexible substrates with printing techniques. These composites should exhibit low sheet resistance and high durability to thermal stresses. In this article, the properties of polymer composites prepared by mixing a commercial solution of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) in aliphatic hydrocarbons with multi-wall carbon nanotubes or graphite platelet nanofibers were described. These composites were coated on flexible and low-cost substrates with screen printing techniques. The microstructure of fabricated layers were observed in a top and cross-sectional view and their thickness was measured with a contact profilometer. Their resistance was measured with a four-point-probe method depending on a printing multiplicity and after exposure the tested samples to the influence of temperature variation. Temperature distribution under influence of current flow in the produced layers was also examined.

  2. Pyrolysis of municipal plastic wastes: Influence of raw material composition.

    Science.gov (United States)

    López, A; de Marco, I; Caballero, B M; Laresgoiti, M F; Adrados, A

    2010-04-01

    The objective of this work is the study of pyrolysis as a feedstock recycling process, for valorizing the rejected streams that come from industrial plants, where packing and packaging wastes are classified and separated for their subsequent mechanical recycling. Four real samples collected from an industrial plant at four different times of the year, have been pyrolysed under nitrogen in a 3.5dm(3) autoclave at 500 degrees C for 30min. Pyrolysis liquids are a complex mixture of organic compounds containing valuable chemicals as styrene, ethyl-benzene, toluene, etc. Pyrolysis solids are composed of the inorganic material contained in the raw materials, as well as of some char formed in the pyrolysis process, and pyrolysis gases are mainly composed of hydrocarbons together with some CO and CO(2), and have very high gross calorific values (GCV). It has been proved by the authors that the composition of the raw material (paper, film, and metals contents) plays a significant role in the characteristics of pyrolysis products. High paper content yields water in the pyrolysis liquids, and CO and CO(2) in the gases, high PE film content gives rise to high viscosity liquids, and high metals content yields more aromatics in the liquid products, which may be attributed to the metals catalytic effect.

  3. Influence of the light-curing unit, storage time and shade of a dental composite resin on the fluorescence

    Science.gov (United States)

    Queiroz, R. S.; Bandéca, M. C.; Calixto, L. R.; Gaiao, U.; Cuin, A.; Porto-Neto, S. T.

    2010-07-01

    The aim of this study was to determine the influence of three light-curing units, storage times and colors of the dental composite resin on the fluorescence. The specimens (diameter 10.0 ± 0.1 mm, thickness 1.0 ± 0.1 mm) were made using a stainless steel mold. The mold was filled with the microhybrid composite resin and a polyethylene film covered each side of the mold. After this, a glass slide was placed on the top of the mold. To standardize the top surface of the specimens a circular weight (1 kg) with an orifice to pass the light tip of the LCU was placed on the top surface and photo-activated during 40 s. Five specimens were made for each group. The groups were divided into 9 groups following the LCUs (one QTH and two LEDs), storage times (immediately after curing, 24 hours, 7 and 30 days) and colors (shades: A2E, A2D, and TC) of the composite resin. After photo-activation, the specimens were storage in artificial saliva during the storage times proposed to each group at 37°C and 100% humidity. The analysis of variance (ANOVA) and Tukey’s posthoc tests showed no significant difference between storage times (immediately, 24 hours and 30 days) ( P > 0.05). The means of fluorescence had difference significant to color and light-curing unit used to all period of storage ( P 0.05).

  4. Competition among pressure groups for political influence over the determination of accounting standards

    OpenAIRE

    Klumpes, P J M

    1998-01-01

    This paper integrates prior studies of accounting policy choice and lobbying activities by testing the empirical implications of Becker''s (1983) theory of competition among pressure groups for political influence over the determination of accounting standards. The theory is applied to explain the nature and outcome of conflict among pressure groups representing financial intermediaries (suppliers) and pension fund members (users) over the development of conflicting Australian pension account...

  5. Territory quality determines social group composition in Ethiopian wolves Canis simensis.

    Science.gov (United States)

    Tallents, Lucy A; Randall, Deborah A; Williams, Stuart D; Macdonald, David W

    2012-01-01

    1. We contrast the value of four different models to predict variation in territory size as follows: resource density (the ideal free distribution), population density, group size and intruder pressure (relative resource-holding potential). In the framework of the resource dispersion hypothesis, we test the effect of resource abundance and spatial variation in resource distribution on the age/sex composition of social groups. 2. We explore these drivers of territory size and group size/composition in Ethiopian wolves Canis simensis in the Bale Mountains, Ethiopia, using fine-scale distribution maps of their major prey species based on satellite-derived vegetation maps. 3. The number of adult males is correlated with territory size, while prey density, wolf population density and intruder pressure are not associated with territory size. On average, each additional adult male increases territory size by 1.18 km(2). 4. Prey abundance increases with territory size (average biomass accumulation of 6.5 kg km(-2)), and larger territories provide greater per capita access to prime foraging habitat and prey. 5. The age/sex composition of wolf packs is more closely related to territory quality than territory size. Subordinate adult females are more likely to be present in territories with greater proportions of prime giant molerat Tachyoryctes macrocephalus habitat (i.e. >80% of Web Valley territories and >20% in Sanetti/Morebawa), and more yearlings (aged 12-23 months) occur in territories with greater overall prey biomass. 6. Wolf packs with restricted access to good foraging habitat tend to defend more exclusive territories, having a lower degree of overlap with neighbouring packs. 7. The greater per capita access to prey in large groups suggests a strong evolutionary advantage of collaborative territorial defence in this species, although the relative costs of territorial expansion vs. exclusion depend upon the spatial distribution of resources. We propose a model

  6. Influence of surface roughness on the color of dental-resin composites

    Institute of Scientific and Technical Information of China (English)

    Razvan GHINEA; Laura UGARTE-ALVAN; Ana YEBRA; Oscar E. PECHO; Rade D. PARAVINA; Maria del Mar PEREZ

    2011-01-01

    This study deals with the influence of surface roughness on the color of resin composites.Ten resin composites (microfilled,hybrid,and microhybrid) were each polished with 500-grit,1200-grit,2000-grit,and 4000-grit SiC papers.The roughness parameter (Ra) was measured using a Plμ confocal microscope,and field-emission scanning electron microscope (Fe-SEM) images were used to investigate filler morphology.Color was measured using a spectroradiometer and a D65 standard illuminant (geometry diffuse/0° specular component excluded (SCE) mode).Surface roughness decreased,with grit number and was not influenced by filler size or size distribution.A significant influence of Ra on lightness (L) was found.Lightness increased with decreases in roughness,except for specimens that underwent polishing procedure 4 (PP4; 500-grit,1200-grit,2000-grit,and 4000-grit SiC papers consecutively).Generally,it was found that surface roughness influenced the color of resin composites.The composites that underwent PP1 (500-grit SiC paper) exhibited significant differences in chroma (C),hue (h°),and lightness (L*) compared to composites that underwent PP3 (500-grit,1200-grit,and 2000-grit SiC papers consecutively) and PP4.Color difference (△E*) between the polishing procedures was within acceptability thresholds in dentistry.

  7. Effect of stacking sequence on the coefficients of mutual influence of composite laminates

    Science.gov (United States)

    Dupir (Hudișteanu, I.; Țăranu, N.; Axinte, A.

    2016-11-01

    Fiber reinforced polymeric (FRP) composites are nowadays widely used in engineering applications due to their outstanding features, such as high specific strength and specific stiffness as well as good corrosion resistance. A major advantage of fibrous polymeric composites is that their anisotropy can be controlled through suitable choice of the influencing parameters. The unidirectional fiber reinforced composites provide much higher longitudinal mechanical properties compared to the transverse ones. Therefore, composite laminates are formed by stacking two or more laminas, with different fiber orientations, as to respond to complex states of stresses. These laminates experience the effect of axial-shear coupling, which is caused by applying normal or shear stresses, implying shear or normal strains, respectively. The normal-shear coupling is expressed by the coefficients of mutual influence. They are engineering constants of primary interest for composite laminates, since the mismatch of the material properties between adjacent layers can produce interlaminar stresses and/or plies delamination. The paper presents the variation of the in-plane and flexural coefficients of mutual influence for three types of multi-layered composites, with different stacking sequences. The results are obtained using the Classical Lamination Theory (CLT) and are illustrated graphically in terms of fiber orientations, for asymmetric, antisymmetric and symmetric laminates. Conclusions are formulated on the variation of these coefficients, caused by the stacking sequence.

  8. Sonochemically synthesized iron-doped zinc oxide nanoparticles: Influence of precursor composition on characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Anirban [Department of Chemical Engineering, University of Calcutta, 92, Acharya P. C. Road, Kolkata 700 009 (India); Maitra, Saikat [Government College of Engineering and Ceramic Technology, 73, A.C. Banerjee Lane, Kolkata 700 010 (India); Ghosh, Sobhan [Managing Innovations, House No. 188, Sector 14, Faridabad 121 007 (India); Chakrabarti, Sampa, E-mail: scchemengg@caluniv.ac.in [Department of Chemical Engineering, University of Calcutta, 92, Acharya P. C. Road, Kolkata 700 009 (India); Centre for Research in Nanoscience & Nanotechnology, University of Calcutta JD- 2, Sector-III, Salt Lake, Kolkata 700 098 (India)

    2016-02-15

    Highlights: • Sonochemical synthesis of iron-doped zinc oxide nanoparticles. • Green synthesis without alkali at room temperature. • Characterization by UV–vis spectroscopy, FESEM, XRD and EDX. • Influence of precursor composition on characteristics. • Composition and characteristics are correlated. - Abstract: Iron-doped zinc oxide nanoparticles have been synthesized sonochemically from aqueous acetyl acetonate precursors of different proportions. Synthesized nanoparticles were characterized with UV–vis spectroscopy, X-ray diffraction and microscopy. Influences of precursor mixture on the characteristics have been examined and modeled. Linear correlations have been proposed between dopant dosing, extent of doping and band gap energy. Experimental data corroborated with the proposed models.

  9. A STUDY OF THE INFLUENCE OF INTERFACIAL DAMAGE ON STRESS CONCENTRATIONS IN INTRAPLY HYBRID COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    Zeng Qingdun; Lin Xuehui

    2001-01-01

    In the axial tensile failure process of intraply hybrid composites, the breakage of some fibers may lead to interfacial damage, thus directly influencing the local stress concentrations near the sites of breakage. A modified shear-lag model, in which the interfacial damage is considered, is proposed. Based on the model, the influence of interfacial shear strength on the stress concentrations and the lengths of interfacial damage zone is first studied. The present results also provide an important theoretical basis for investigating the failure mechanism and hybrid effects for such kind of composites.

  10. Influence of rare earth element Y on composition, microstructure and inclusion of the weld

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper, the influence of rare element Y on the composition, microstructure and inclusions of the weld metal has been studied by using the method of "alloy addition in a molten pool". The results show: (1) The composition of the weld metal is not obviously affected by little amount of Y-SiFe addition. (2) Y-SiFe can make weld microstructure fine and raise the hardness of the weld. (3) Y-SiFe has not obvious influence on the inclusion size. (4) When the amount of Y is a little, Y accumulates in the silicates of Ti, Mn and other compound inclusion with MnS.

  11. The influence of comonomer composition on dimethacrylate resin properties for dental composites.

    Science.gov (United States)

    Anseth, K S; Goodner, M D; Reil, M A; Kannurpatti, A R; Newman, S M; Bowman, C N

    1996-08-01

    During the polymerization of multifunctional monomers for dental restorations, typical final double-bond conversions range from 55 to 75%. The low conversion results in a large amount of extractable monomer, reduced adhesion to the filler, and the potential for increased swelling. In this work, the ability to increase the maximum conversion by optimizing the copolymer composition is explored. A series of multi-ethylene glycol dimethacrylate monomers of various lengths was used as a model system to determine how the copolymer composition affects the final conversion, the mechanical properties, and the predicted shrinkage. It was found that the ultimate conversion can be significantly increased, shrinkage decreased, and mechanical properties maintained. It was found that up to 30 wt% of poly(ethylene glycol) 600 dimethacrylate could be added to diethylene glycol dimethacrylate without reducing the strength and increasing the conversion. Results for other comonomer combinations were similar.

  12. Influence of Alumina Addition on the Optical Property of Zirconia/Alumina Composite Dental Ceramics

    Institute of Scientific and Technical Information of China (English)

    JIANG Li; LIAO Yunmao; LI Wei; WAN Qianbing; ZHAO Yongqi

    2011-01-01

    The influence of various alumina additions on the optical property of zirconia/alumina composite ceramics was investigated.The relative sintered densities,transmittances,color and the microstructure of the composite ceramics were studied.The experimental results showed that the relative sintered densities and transmittances decreased with alumina addition.The lightness increased obviously but the chroma change was small.Pure zirconia nanopowders sintered densely could obtain the relatively high transmittance,while the transmittance and the lightness of slight addition changed significantly.The zirconia/alumina composite ceramics with alumina addition less than 7.5wt% could achieve the relatively stable and reliable optical properties.

  13. Clinical dental adhesive application: the influence on composite-enamel interface morphology.

    Science.gov (United States)

    Matei, Ruxandra; Popescu, Mihai Raul; Suciu, Mircea; Rauten, Anne Marie

    2014-01-01

    Although the adhesion phenomenon is crucial in achieving and maintaining a composite building on dental structure, this phenomenon is not completely understood. On the other hand, adhesion is dependent on the interface quality (the interface between enamel and adhesive). In this study, the authors approached the subject of the influence of adhesive clinical application on the composite-enamel interface, which was less investigated by the scientists. On intact extracted human teeth were prepared enamel areas, and then filled with light-curing composite. The teeth were sectioned and prepared for microscopic investigation, at 10×, 100× and 200× magnifications.

  14. Research on the nanolevel influence of surfactants on structure formation of the hydrated Portland cement compositions

    Directory of Open Access Journals (Sweden)

    Guryanov Alexander

    2016-01-01

    Full Text Available The research of the structure formation process on a nanolevel of the samples of hydrated Portland cement compositions containing the modifying additives has been conducted with the help of small angle neutron scattering method. Carbonate and aluminum alkaline slimes as well as the complex additives containing surfactants were used as additives. The influence of slimes and surfactants on structural parameters change of Portland cement compositions of the average size of the disseminating objects, fractal dimension samples is considered. These Portland cement compositions are shown to be fractal clusters.

  15. Mapping lichen color-groups in western Arctic Alaska using seasonal Landsat composites

    Science.gov (United States)

    Nelson, P.; Macander, M. J.; Swingley, C. S.

    2016-12-01

    Mapping lichens at a landscape scale has received increased recent interest due to fears that terricolous lichen mats, primary winter caribou forage, may be decreasing across the arctic and boreal zones. However, previous efforts have produced taxonomically coarse, total lichen cover maps or have covered relatively small spatial extents. Here we attempt to map lichens of differing colors as species proxies across northwestern Alaska to produce the finest taxonomic and spatial- grained lichen maps covering the largest spatial extent to date. Lichen community sampling in five western Alaskan National Parks and Preserves from 2007-2012 generated 328 FIA-style 34.7 m radius plots on which species-level macrolichen community structure and abundance was estimated. Species were coded by color and plot lichen cover was aggregated by plot as the sum of the cover of each species in a color group. Ten different lichen color groupings were used for modeling to deduce which colors were most detectable. Reflectance signatures of each plot were extracted from a series of Landsat composites (circa 2000-2010) partitioned into two-week intervals from June 1 to Sept. 15. Median reflectance values for each band in each pixel were selected based on filtering criteria to reduce likelihood of snow cover. Lichen color group cover was regressed against plot reflectance plus additional abiotic predictors in two different data mining algorithms. Brown and grey lichens had the best models explaining approximately 40% of lichen cover in those color groups. Both data mining techniques produced similarly good fitting models. Spatial patterns of lichen color-group cover show distinctly different ecological patterns of these color-group species proxies.

  16. EEG reveals an early influence of social conformity on visual processing in group pressure situations.

    Science.gov (United States)

    Trautmann-Lengsfeld, Sina Alexa; Herrmann, Christoph Siegfried

    2013-01-01

    Humans are social beings and often have to perceive and perform within groups. In conflict situations, this puts them under pressure to either adhere to the group opinion or to risk controversy with the group. Psychological experiments have demonstrated that study participants adapt to erroneous group opinions in visual perception tasks, which they can easily solve correctly when performing on their own. Until this point, however, it is unclear whether this phenomenon of social conformity influences early stages of perception that might not even reach awareness or later stages of conscious decision-making. Using electroencephalography, this study has revealed that social conformity to the wrong group opinion resulted in a decrease of the posterior-lateral P1 in line with a decrease of the later centro-parietal P3. These results suggest that group pressure situations impact early unconscious visual perceptual processing, which results in a later diminished stimulus discrimination and an adaptation even to the wrong group opinion. These findings might have important implications for understanding social behavior in group settings and are discussed within the framework of social influence on eyewitness testimony.

  17. Sorting out compositional trends in sedimentary rocks of the Bradbury group (Aeolis Palus), Gale crater, Mars

    Science.gov (United States)

    Siebach, K. L.; Baker, M. B.; Grotzinger, J. P.; McLennan, S. M.; Gellert, R.; Thompson, L. M.; Hurowitz, J. A.

    2017-02-01

    Sedimentary rocks are composed of detrital grains derived from source rocks, which are altered by chemical weathering, sorted during transport, and cemented during diagenesis. Fluvio-lacustrine sedimentary rocks of the Bradbury group, observed on the floor of Gale crater by the Curiosity rover during its first 860 Martian solar days, show trends in bulk chemistry that are consistent with sorting of mineral grains during transport. The Bradbury group rocks are uniquely suited for sedimentary provenance analysis because they appear to have experienced negligible cation loss (i.e., open-system chemical weathering) at the scale of the Alpha Particle X-ray Spectrometer bulk chemistry analyses based on low Chemical Index of Alteration values and successful modeling of >90% of the (volatile-free) targets as mixtures of primary igneous minerals. Significant compositional variability between targets is instead correlated to grain-size and textural characteristics of the rocks; the coarsest-grained targets are enriched in Al2O3, SiO2, and Na2O, whereas the finer-grained targets are enriched in mafic components. This is consistent with geochemical and mineralogical modeling of the segregation of coarse-grained plagioclase from finer-grained mafic minerals (e.g., olivine and pyroxenes), which would be expected from hydrodynamic sorting of the detritus from mechanical breakdown of subalkaline plagioclase-phyric basalts. While the presence of a distinctive K2O-rich stratigraphic interval shows that input from at least one distinctive alkali-feldspar-rich protolith contributed to basin fill, the dominant compositional trends in the Bradbury group are consistent with sorting of detrital minerals during transport from relatively homogeneous plagioclase-phyric basalts.

  18. Do stakeholder groups influence environmental management system development in the Dutch agri-food sector?

    NARCIS (Netherlands)

    Bremmers, H.J.; Omta, S.W.F.; Kemp, R.G.M.; Haverkamp, D.J.

    2007-01-01

    This paper presents the results of a survey that included 492 companies in the Dutch agri-food sector with respect to the influence of stakeholder groups on the companies' level of environmental management system (EMS) implementation. It is concluded that primary stakeholders (government, clients) a

  19. Influence of a Teacher's Scaffolding Moves during Child-Led Small-Group Discussions

    Science.gov (United States)

    Jadallah, May; Anderson, Richard C.; Nguyen-Jahiel, Kim; Miller, Brian W.; Kim, Il-Hee; Kuo, Li-Jen; Dong, Ting; Wu, Xiaoying

    2011-01-01

    The influence of one teacher's scaffolding moves on children's performance in free-flowing child-led small-group discussions was investigated. Three moves were examined: prompting for and praising the use of evidence, asking for clarification, and challenging. Lag sequential analysis was applied to a corpus of over 5,300 speaking turns during 30…

  20. Perceptual Grouping in Haptic Search: The Influence of Proximity, Similarity, and Good Continuation

    Science.gov (United States)

    Overvliet, Krista E.; Krampe, Ralf Th.; Wagemans, Johan

    2012-01-01

    We conducted a haptic search experiment to investigate the influence of the Gestalt principles of proximity, similarity, and good continuation. We expected faster search when the distractors could be grouped. We chose edges at different orientations as stimuli because they are processed similarly in the haptic and visual modality. We therefore…

  1. Perceptions of Factors Influencing Healthful Food Consumption Behavior in the Lower Mississippi Delta: Focus Group Findings

    Science.gov (United States)

    McGee, Bernestine B.; Richardson, Valerie; Johnson, Glenda S.; Thornton, Alma; Johnson, Crystal; Yadrick, Kathleen; Ndirangu, Murugi; Goolsby, Susan; Watkins, Debra; Simpson, Pippa M.; Hyman, Edith; Stigger, Flavelia; Bogle, Margaret L.; Kramer, Tim R.; Strickland, Earline; McCabe-Sellers, Beverly

    2008-01-01

    Objective: To identify perceptions of Lower Mississippi Delta (LMD) residents regarding factors that influence a change in healthful food consumption behavior to assist in planning sustainable nutrition interventions in the LMD. Design: Nine focus groups were conducted with LMD residents in 9 counties in Arkansas, Louisiana, and Mississippi. One…

  2. Perceptions of Factors Influencing Healthful Food Consumption Behavior in the Lower Mississippi Delta: Focus Group Findings

    Science.gov (United States)

    McGee, Bernestine B.; Richardson, Valerie; Johnson, Glenda S.; Thornton, Alma; Johnson, Crystal; Yadrick, Kathleen; Ndirangu, Murugi; Goolsby, Susan; Watkins, Debra; Simpson, Pippa M.; Hyman, Edith; Stigger, Flavelia; Bogle, Margaret L.; Kramer, Tim R.; Strickland, Earline; McCabe-Sellers, Beverly

    2008-01-01

    Objective: To identify perceptions of Lower Mississippi Delta (LMD) residents regarding factors that influence a change in healthful food consumption behavior to assist in planning sustainable nutrition interventions in the LMD. Design: Nine focus groups were conducted with LMD residents in 9 counties in Arkansas, Louisiana, and Mississippi. One…

  3. Learning Mathematics with Technology: The Influence of Virtual Manipulatives on Different Achievement Groups

    Science.gov (United States)

    Moyer-Packenham, Patricia; Suh, Jennifer

    2012-01-01

    This study examined the influence of virtual manipulatives on different achievement groups during a teaching experiment in four fifth-grade classrooms. During a two-week unit focusing on two rational number concepts (fraction equivalence and fraction addition with unlike denominators) one low achieving, two average achieving, and one high…

  4. Interest groups: a survey of empirical models that try to assess their influence

    NARCIS (Netherlands)

    Potters, J.J.M.; Sloof, R.

    1996-01-01

    Substantial political power is often attributed to interest groups. The origin of this power is not quite clear, though, and the mechanisms by which influence is effectuated are not yet fully understood. The last two decades have yielded a vast number of studies which use empirical models to assess

  5. Attitudes to Language Learning: A Comparative Study of Peer Group Influences

    Science.gov (United States)

    Bartram, Brendan

    2006-01-01

    This article examines the nature and influence of peer group perceptions on pupils' attitudes to learning German and French. It begins with an overview of key findings from the literature, before reviewing selected results from a large PhD attitudinal survey using a multi-stage qualitative research design. The article focuses on the perceptions of…

  6. The Social Group Influences of US Health Journalists and Their Impact on the Newsmaking Process

    Science.gov (United States)

    McCauley, M. P.; Blake, K. D.; Meissner, H. I.; Viswanath, K.

    2013-01-01

    The news media play a vital role in disseminating health information, yet little is known about the social characteristics of health journalists or the impact they have on the newsmaking process. This study examines how the social group influences of US health journalists impact two important aspects of news production--"media agenda-setting" and…

  7. Assessment of Groups Influence on Management Style as Related to University Governance

    Science.gov (United States)

    Irtwange, S. V.; Orsaah, S.

    2010-01-01

    The study was undertaken with the objective of assessing groups influence on management style as related to University governance with University of Agriculture, Makurdi as a case study from academic staff perspective. The management style of the Vice Chancellor of the University of Agriculture, Makurdi between the period September 3, 1996 to…

  8. Assessment of Groups Influence on Management Style as Related to University Governance

    Science.gov (United States)

    Irtwange, S. V.; Orsaah, S.

    2010-01-01

    The study was undertaken with the objective of assessing groups influence on management style as related to University governance with University of Agriculture, Makurdi as a case study from academic staff perspective. The management style of the Vice Chancellor of the University of Agriculture, Makurdi between the period September 3, 1996 to…

  9. Party over policy: The dominating impact of group influence on political beliefs.

    Science.gov (United States)

    Cohen, Geoffrey L

    2003-11-01

    Four studies demonstrated both the power of group influence in persuasion and people's blindness to it. Even under conditions of effortful processing, attitudes toward a social policy depended almost exclusively upon the stated position of one's political party. This effect overwhelmed the impact of both the policy's objective content and participants' ideological beliefs (Studies 1-3), and it was driven by a shift in the assumed factual qualities of the policy and in its perceived moral connotations (Study 4). Nevertheless, participants denied having been influenced by their political group, although they believed that other individuals, especially their ideological adversaries, would be so influenced. The underappreciated role of social identity in persuasion is discussed.

  10. Influence of pre-Mississippian paleogeology on Carboniferous Lisburne Group, Arctic National Wildlife Refuge, northeastern Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Watts, K.F.; Carlson, R.; Imm, T.; Gruzlovic, P.; Hanks, C.

    1988-01-01

    The Carboniferous Lisburne Group of northern Alaska formed an extensive carbonate platform, which was later deformed as part of the Brooks Range fold and thrust belt. In the northeast, the Lisburne Group is parautochthonous and analogous to that at Prudhoe Bay. The Lisburne's paleogeography and facies relationships pertain to assessment of the petroleum potential of the Arctic National Wildlife Refuge (ANWR). The Franklinian paleogeology, unconformably underlying the Ellesmerial sequence, has influenced sedimentation patterns in the Lisburne Group. The transgressive Endicott Group (Kekiktuk conglomerate and Kayak Shale) and Lisburne Group thin northward over Franklinian basement highs. In the Sadlerochit Mountains, the Katakturuk Dolomite formed a paleotopographic high over which the Endicott Group pinched out and the Lisburne Group thinned. Shallow-marine oolitic grainstone developed in the cyclic Pennsylvanian Wahoo Limestone. To the south in the Shublik Mountains, a repeated sequence of Katakturuk Dolomite and the Nanook Limestone were lower, so the Endicott Group lapped over the area and was later overlain by comparable Lisburne Group rocks. In the Fourth Range, the Lisburne Group is thicker and limestones also occur in the upper Endicott Group. Oolitic grainstone in the Wahoo Limestone is rare, and broad ooid shoals apparently pinched out into deeper water carbonates on a southward sloping carbonate ramp.

  11. Functional group composition of ambient and source organic aerosols determined by tandem mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Dron, J.; El Haddad, I.; Temime-Roussel, B.; Wortham, H.; Marchand, N. [Univ Aix Marseille, CNRS, Lab Chim Provence, Equipe Instrumentat and React Atmospher, UMR 6264, F-13331 Marseille 3 (France); Jaffrezo, J.L. [Univ Grenoble 1, CNRS, UMR 5183, Lab Glaciol and Geophys Environm, F-38402 St Martin Dheres (France)

    2010-07-01

    The functional group composition of various organic aerosols (OA) is investigated using a recently developed analytical approach based on atmospheric pressure chemical ionisation-tandem mass spectrometry (APCIMS/MS). The determinations of three functional groups contents are performed quantitatively by neutral loss (carboxylic and carbonyl groups, R-COOH and R-CO-R' respectively) and precursor ion (nitro groups, R-NO{sub 2}) scanning modes of a tandem mass spectrometer. Major organic aerosol sources are studied: vehicular emission and wood combustion for primary aerosol sources; and a secondary organic aerosol (SOA) produced through photooxidation of o-xylene. The results reveal significant differences in the functional group contents of these source aerosols. The laboratory generated SOA is dominated by carbonyls while carboxylics are preponderate in the wood combustion particles. On the other hand, vehicular emissions are characterised by a strong nitro content. The total amount of the three functional groups accounts for 1.7% (vehicular) to 13.5% (o-xylene photooxidation) of the organic carbon. Diagnostic functional group ratios are then used to tentatively discriminate sources of particles collected in an urban background environment located in an Alpine valley (Chamonix, France) during a strong winter pollution event. The three functional groups under study account for a total functionalization rate of 2.2 to 3.8% of the organic carbon in this ambient aerosol, which is also dominated by carboxylic moieties. In this particular case study of a deep alpine valley during winter, we show that the nitro- and carbonyl-to-carboxylic diagnostic ratios can be a useful tool to discriminate sources. In these conditions, the total OA concentrations are highly dominated by wood combustion OA. This result is confirmed by an organic markers source apportionment approach which assess a wood burning organic carbon contribution of about 60%. Finally, examples of functional

  12. Functional group composition of ambient and source organic aerosols determined by tandem mass spectrometry

    Directory of Open Access Journals (Sweden)

    J. Dron

    2010-08-01

    Full Text Available The functional group composition of various organic aerosols (OA is investigated using a recently developed analytical approach based on atmospheric pressure chemical ionisation-tandem mass spectrometry (APCI-MS/MS. The determinations of three functional groups contents are performed quantitatively by neutral loss (carboxylic and carbonyl groups, R-COOH and R-CO-R´ respectively and precursor ion (nitro groups, R-NO2 scanning modes of a tandem mass spectrometer. Major organic aerosol sources are studied: vehicular emission and wood combustion for primary aerosol sources; and a secondary organic aerosol (SOA produced through photooxidation of o-xylene. The results reveal significant differences in the functional group contents of these source aerosols. The laboratory generated SOA is dominated by carbonyls while carboxylics are preponderate in the wood combustion particles. On the other hand, vehicular emissions are characterised by a strong nitro content. The total amount of the three functional groups accounts for 1.7% (vehicular to 13.5% (o-xylene photooxidation of the organic carbon. Diagnostic functional group ratios are then used to tentatively discriminate sources of particles collected in an urban background environment located in an Alpine valley (Chamonix, France during a strong winter pollution event. The three functional groups under study account for a total functionalisation rate of 2.2 to 3.8% of the organic carbon in this ambient aerosol, which is also dominated by carboxylic moieties. In this particular case study of a deep alpine valley during winter, we show that the nitro- and carbonyl-to-carboxylic diagnostic ratios can be a useful tool to discriminate sources. In these conditions, the total OA concentrations are highly dominated by wood combustion OA. This result is confirmed by an organic markers source apportionment approach which assess a wood burning organic carbon contribution of about 60

  13. Influence of the Head Group Size on the Direction of Tilt in Langmuir Monolayers

    CERN Document Server

    Schmid, F

    1996-01-01

    A model of rods with heads of variable size, which are confined to a planar surface, is used to study the influence of the head group size on tilted phases in Langmuir monolayers. Simple free energy considerations as well as exact zero temperature calculations indicate that molecules with small head groups tilt towards next nearest neighbors, and molecules with larger head groups towards nearest neighbors. This provides a possible explanation for recent experimental results, and for details of the generic phase diagram for fatty acid monolayers.

  14. The influence of X-semipermutability of subgroups on the structure of finite groups

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Let A be a subgroup of a group G and X be a nonempty subset of G. A is said to be X-semipermutable in G if A has a supplement T in G such that A is X-permutable with every subgroup of T. In this paper, we investigate further the influence of X-semipermutability of some subgroups on the structure of finite groups. Some new criteria for a group G to be supersoluble or p-nilpotent are obtained.

  15. Composite resin's adhesive resistance to dentin: influence of Er:YAG laser focal distance variation.

    Science.gov (United States)

    Corona, Silmara Aparecida Milori; Atoui, Juliana Abdallah; Chimello, Daniela Thomazatti; Borsatto, Maria Cristina; Pecora, Jesus Djalma; Dibb, Regina Guenka Palma

    2005-04-01

    The aim of this study was to analyze in vitro the influence of Er:YAG laser focal distance variation on tensile bond strength of a composite resin to dentin. Although there are several studies using the Er:YAG laser for dentin treatment, there is a lack of available literature related to the Er:YAG laser focal distance variation. Sixty vestibular and lingual dentin surfaces from extracted human third molars, kept in a 0.4% azide sodium solution, were ground and assigned to six groups. The control group was conditioned with 35% phosphoric acid (CA). In the lased groups, the dentin surface treatment was performed by irradiation with Er:YAG laser (80 mJ/2 Hz), varying the focal distance (11, 12, 14, 16, and 17 mm), followed by acid etching. The Single Bond/Filtek Z250 (3M) resinous system was used for the specimen manufacture. The tensile bond strength tests were performed in a Universal Testing Machine with 50 kgf load cell and 0.5 mm/min cross head speed. The averages in MPa were: CA: 18.03 (+/-2.09); 11 mm; 9.92 (+/-3.34); 12 mm: 9.49 (+/-2.29); 14 mm: 10.99 (+/-3.45); 16 mm: 10.56 (+/-1.93); and 17 mm: 17.05 (+/-2.31). It was concluded that the application of Er:YAG laser in a defocused mode (17 mm) associated with acid etching was similar to the treatment of acid solely. Er:YAG laser irradiation in a focused (12 mm) and a defocused (11, 14, and 16 mm) mode coupled with acid conditioning produced the lowest values of adhesion.

  16. Effects of plant diversity, functional group composition, and fertilization on soil microbial properties in experimental grassland.

    Directory of Open Access Journals (Sweden)

    Tanja Strecker

    Full Text Available Loss of biodiversity and increased nutrient inputs are two of the most crucial anthropogenic factors driving ecosystem change. Although both received considerable attention in previous studies, information on their interactive effects on ecosystem functioning is scarce. In particular, little is known on how soil biota and their functions are affected by combined changes in plant diversity and fertilization.We investigated the effects of plant diversity, functional community composition, and fertilization on the biomass and respiration of soil microbial communities in a long-term biodiversity experiment in semi-natural grassland (Jena Experiment. Plant species richness enhanced microbial basal respiration and microbial biomass, but did not significantly affect microbial specific respiration. In contrast, the presence of legumes and fertilization significantly decreased microbial specific respiration, without altering microbial biomass. The effect of legumes was superimposed by fertilization as indicated by a significant interaction between the presence of legumes and fertilization. Further, changes in microbial stoichiometry (C-to-N ratio and specific respiration suggest the presence of legumes to reduce N limitation of soil microorganisms and to modify microbial C use efficiency.Our study highlights the role of plant species and functional group diversity as well as interactions between plant community composition and fertilizer application for soil microbial functions. Our results suggest soil microbial stoichiometry to be a powerful indicator of microbial functioning under N limited conditions. Although our results support the notion that plant diversity and fertilizer application independently affect microbial functioning, legume effects on microbial N limitation were superimposed by fertilization, indicating significant interactions between the functional composition of plant communities and nutrient inputs for soil processes.

  17. The Influence of Some Romanian Interest Groups Upon the Activity of Government and Parliament

    Directory of Open Access Journals (Sweden)

    Bianca COBÂRZAN

    2005-10-01

    Full Text Available The paper focuses on two specific interest groups, NGOs and trade unions, and on their influence upon the government and parliament. Our paper is based on an analyze of the activity of several interest groups during the period 2002-2004 and on the results of several researches and reports published on the last years. The analyze identifies petitioning for rule making, public meetings and debates, monitoring the activity of the public institutions and participating in advisory or regulatory committees as being the most common used mechanisms to influence the government and the parliament in Romania. Also, the analyze shows that administrative procedures affect the degree of bureaucratic autonomy. Overall, the results of this brief research show some pluralist forms of the interaction between the interest groups and the public institutions.

  18. Factors influencing surfactant composition in the newborn infant.

    Science.gov (United States)

    Obladen, M

    1978-07-01

    In order to evaluate the surfactant maturation of the neonate, tracheal aspirates were analyzed in 84 newborn infants with 12h of birth. Using 2-dimensional thin-layer chromatography, 9 different phospholipids were identified. Dynamic surface tension measurements were performed with a modified Wilhelmy balance. Five different groups of infants with typical phospholipid patterns were characterized: i.e., 1. Normal term newborn. 2. RDS in the preterm infant. 3. Acceleration of lung maturity in preterm infants without RDS. 4. Retardation in term infants with RDS. 5. Therapeutic induction of pulmonary maturity in preterm infants following maternal glucocorticoid administration. Mature lung effluent contains high concentrations of phosphatidylcholine (PC) and phsophatidylglycerol (PG). In infants with RDS, PC is low and PG absent. Accelerated lung maturity was observed after chronic prenatal stress, such as prolonged rupture of the membranes, chronic vaginal bleeding, and maternal hepatitis or drug addiction. Retardation of pulmonary maturity was seen in infants with alpha-1-AT-deficiency, maternal diabetes and maternal hypothyroidism. Administration of methylprednisolone to the mother 24 h to 72h before birth induced both the synthesis of PC and PG in the preterm infants, resulting in an almost full-term phospholipid pattern as early as 31 weeks of gestation. The significance of these factors on the pathogenesis of RDS is discussed.

  19. Prediction of small molecules' metabolic pathways based on functional group composition.

    Science.gov (United States)

    Lu, Jin; Niu, Bing; Liu, Liang; Lu, Wen-Cong; Cai, Yu-Dong

    2009-01-01

    How to correctly and efficiently determine small molecules' biological function is a challenge and has a positive effect on further metabonomics analysis. Here, we introduce a computational approach to address this problem. The new approach is based on AdaBoost method and featured by function group composition to the metabolic pathway analysis, which can fast and automatically map the small chemical molecules back to the possible metabolic pathway that they belong to. As a result, jackknife cross validation test and independent set test on the model reached 73.7% and 73.8%, respectively. It can be concluded that the current approach is very promising for mapping some unknown molecules' possible metabolic pathway. An online predictor developed by this research is available at http://chemdata.shu.edu.cn/pathway.

  20. Influence of alkali ion doping on the electrochemical performances of tin-based composite materials

    Energy Technology Data Exchange (ETDEWEB)

    Aboulaich, A.; Conte, D.E.; Olivier-Fourcade, J.; Jumas, J.C. [Institut Charles Gerhardt-Laboratoire des Agregats, Interfaces et Materiaux pour l' Energie (UMR 5253), Place Eugene Bataillon, 34095 Montpellier Cedex 5 (France); Jordy, C. [SAFT, 111-113 Boulevard Alfred Daney, 33300 Bordeaux Cedex (France); Willmann, P. [Centre National d' Etudes Spatiales, 18 Avenue Edouard Belin, 31401 Toulouse Cedex 9 (France)

    2010-05-15

    In this paper, we report an investigation of three tin-based composite materials as negative electrodes for lithium-ion batteries. Theses composites were synthesized by solid state reaction from dispersion of micrometric tin into BPO{sub 4}, Li-doped BPO{sub 4} (LiBPO) and Na-substituted BPO{sub 4} (NaBPO) matrix, respectively. We have investigated more particularly the influence of the two alkaline ions (Li{sup +}, Na{sup +}) introduced into the matrix on electrochemical performances. The morphology of powders was observed by SEM and the composition studied by EDX analysis. The conductivity measurements showed that the modified BPO{sub 4} matrixes (Li or Na) exhibit improved conductivity ({sigma}{sub RT} = 2 x 10{sup -11} S cm{sup -1} for NaBPO). A focus of our interest was to relate the nature and structural composition of the composite interface between active tin and inactive matrix to the irreversible capacity in this type of composite materials. The electrochemical analysis shows a decrease of the irreversible capacity for the composite based on modified matrixes (around 150 and 190 mAh g{sup -1} for SnNaBPO and SnLiBPO, respectively) with respect to the reference composite SnBPO (245 mAh g{sup -1}). (author)

  1. Influence of alkali ion doping on the electrochemical performances of tin-based composite materials

    Science.gov (United States)

    Aboulaich, A.; Conte, D. E.; Olivier-Fourcade, J.; Jordy, C.; Willmann, P.; Jumas, J. C.

    In this paper, we report an investigation of three tin-based composite materials as negative electrodes for lithium-ion batteries. Theses composites were synthesized by solid state reaction from dispersion of micrometric tin into BPO 4, Li-doped BPO 4 (LiBPO) and Na-substituted BPO 4 (NaBPO) matrix, respectively. We have investigated more particularly the influence of the two alkaline ions (Li +, Na +) introduced into the matrix on electrochemical performances. The morphology of powders was observed by SEM and the composition studied by EDX analysis. The conductivity measurements showed that the modified BPO 4 matrixes (Li or Na) exhibit improved conductivity (σ RT = 2 × 10 -11 S cm -1 for NaBPO). A focus of our interest was to relate the nature and structural composition of the composite interface between active tin and inactive matrix to the irreversible capacity in this type of composite materials. The electrochemical analysis shows a decrease of the irreversible capacity for the composite based on modified matrixes (around 150 and 190 mAh g -1 for SnNaBPO and SnLiBPO, respectively) with respect to the reference composite SnBPO (245 mAh g -1).

  2. How can peer group influence the behavior of adolescents: explanatory model.

    Science.gov (United States)

    Tomé, Gina; Matos, Margarida; Simões, Celeste; Diniz, José Alves; Camacho, Inês

    2012-02-29

    The current work aims to study both the peer group and family influence on adolescent behaviour. In order to achieve the aforementioned objective, an explanatory model based on the Structural Equations Modelling (SEM) was proposed. The sample used was the group of adolescents that participated in the Portuguese survey of the European study Health Behaviour in School-aged Children (HBSC). The Portuguese survey included students from grades 6, 8 and 10 within the public education system, with an average age of 14 years old (SD=1.89). The total sample of the HBSC study carried out in 2006 was 4,877; however with the use of the SEM, 1,238 participants were lost out of the total sample. The results show that peers have a direct influence in adolescents' risk behaviours. The relationship with parents did not demonstrate the expected mediation effect, with the exception of the following elements: relation between type of friends and risk behaviour; and communication with parent and lesser involvement in violence behaviours and increased well-being. The negative influence of the peer group is more connected to the involvement in risk behaviours, whilst the positive influence is more connected with protective behaviours.

  3. Twin study of genetic and environmental influences on adult body size, shape, and composition

    DEFF Research Database (Denmark)

    Schousboe, K; Visscher, P M; Erbas, B;

    2004-01-01

    OBJECTIVE: To investigate the genetic and environmental influences on adult body size, shape, and composition in women and men, and to assess the impact of age. MATERIALS AND METHODS: In this cross-sectional study of 325 female and 299 male like-sex healthy twin pairs, on average 38 y old (18-67 ...

  4. Influence of Processing Parameters on Properties of Needle punched Composite Geotextiles

    Institute of Scientific and Technical Information of China (English)

    李婕; 储才元; 杨金魁; 张键

    2001-01-01

    The influence of the processing parameters on the properties of needle-punched composite geotextiles,compounded by polypropylene filament woven-fabrics and nonwoven fabrics is studied by using orthogonal design method. The relationship between tensile strength and peeling strength is discussed. The experimental results are offered as reference.

  5. Influence of double (w1/o/w2) emulsion composition on lubrication properties

    NARCIS (Netherlands)

    Oppermann, A.K.L.; Verkaaik, Lisa; Stieger, M.A.; Scholten, E.

    2017-01-01

    Double (w1/o/w2) emulsions are potential fat replacers in foods. Fats are known for their lubricating properties, which contribute to texture perception. It is therefore of interest to understand how the composition of double emulsions influences lubrication properties. This study focuses on the

  6. The influence of Ivermectin treatment of cattle on dung fauna and dung composition

    DEFF Research Database (Denmark)

    Madsen, Mogens; Nansen, Peter; Jespersen, Jørgen Brøchner;

    1988-01-01

    Madsen, M., J. Gr¢nvold, P. Nansen, J.B. Jespersen, K.-M. Vagn Jensen, P. Holter and B. Overgaard Nielsen, 1988: The influence of Ivermectin treatment of cattle on dung fauna and dung composition. Programme and Abstracts of the Vth European Multicolloqui¬um of Parasitology, September 4-9, 1988...

  7. The influence of Ivermectin treatment of cattle on dung fauna and dung composition

    DEFF Research Database (Denmark)

    Madsen, Mogens; Nansen, Peter; Jespersen, Jørgen Brøchner

    1988-01-01

    Madsen, M., J. Gr¢nvold, P. Nansen, J.B. Jespersen, K.-M. Vagn Jensen, P. Holter and B. Overgaard Nielsen, 1988: The influence of Ivermectin treatment of cattle on dung fauna and dung composition. Programme and Abstracts of the Vth European Multicolloqui¬um of Parasitology, September 4-9, 1988...

  8. Influence of markets and forest composition on lumber production in Pennsylvania

    Science.gov (United States)

    William G. Luppold; Matthew S. Bumgardner

    2006-01-01

    In this study, we examine regional differences in the hardwood timber resources of Pennsylvania and how the combined changes in inventory volume, forest composition, and lumber prices have influenced regional lumber production. Isolation of these relationships is important because shifts in lumber production reflect changes in harvesting activity. In turn, harvesting...

  9. The Influence of Non-White Pupil Classroom Composition on Classroom Quality.

    Science.gov (United States)

    Frenk, James H.

    The study described here is an attempt to answer the question: does the classroom ratio of non-white to white pupils influence the quality of the behavior of the participants in integrated classrooms? And, if so, is there an optimum ratio of classroom racial composition? To carry out such an investigation, an instrument designed to provide a…

  10. Knoop microhardness and FT-Raman evaluation of composite resins: influence of opacity and photoactivation source

    Directory of Open Access Journals (Sweden)

    Luis Gustavo Barrotte Albino

    2011-06-01

    Full Text Available The aim of this study was to evaluate the degree of conversion by Knoop microhardness (KHN and FT-Raman spectroscopy (FTIR of one nanofilled (Filtek Supreme-3M-ESPE [FS] and one microhybrid composite (Charisma-Heraeus-Kulzer [CH], each with different opacities, namely enamel, dentin, and translucent, which were photo-activated by a quartz-tungsten-halogen lamp (QTH and a light-emitting diode (LED. Resin was bulk inserted into a disc-shaped mold that was 2.0 mm thick and 4 mm in diameter, obtaining 10 samples per group. KHN and FTIR values were analyzed by two-way ANOVA and Tukey's tests (α = 0.05. Nanofilled resin activated by a LED presented higher microhardness values than samples activated by a QTH for dentin opacity (p < 0.05. The microhybrid resin showed no differences in KHN or FTIR values with different activation sources or opacity. The nanofilled dentin and enamel resins showed lower FTIR values than the translucent resin. The KHN values of the translucent resins were not influenced by the light source.

  11. Influence of Stellar Flares on the Chemical Composition of Exoplanets and Spectra

    CERN Document Server

    Venot, Olivia; Carl, Shaun; Hashim, Aysha; Decin, Leen

    2016-01-01

    More than 3000 exoplanets have been detected so far, and more and more spectroscopic observations of exoplanets are performed. Future instruments are eagerly awaited as they will be able to provide spectroscopic data with a greater accuracy and sensitivity than what is currently available. An important aspect to consider is temporal stellar atmospheric disturbances that can influence the planetary composition, and hence spectra, and potentially can lead to incorrect assumptions about the steady-state atmospheric composition of the planet. We focus on perturbations that come from the host star in the form of flare events that significantly increase the photon flux impingement on the exoplanet atmosphere. In some cases, and particularly for M stars, this sudden increase may last for several hours. We aim at answering the question to what extent a stellar flare is able to modify the chemical composition of the planetary atmosphere and, therefore influence the resulting spectra. We use a 1D thermo-photochemical m...

  12. Influence of the curing cycles on the fatigue performance of unidirectional glass fiber reinforced epoxy composites

    DEFF Research Database (Denmark)

    Hüther, Jonas; Brøndsted, Povl

    2016-01-01

    stresses are built up and frozen, as residual stresses occur. In the present work, a glass fiber reinforced epoxy composite laminate with an unidirectional architecture based on non-crimp fabrics with backing fibers is investigated. Three different curing cycles (time-temperature cycles) are used, leading...... demonstrated that the resulting residual stresses barely influences the quasi-static mechanical properties of reinforced glass-fiber composites. It is found that the fatigue performance in the 0° direction is significantly influenced by the internal stresses, whereas the fatigue performance in the off axes......During the manufacturing process of fiber reinforced polymers the curing reaction of the resin results in shrinkage of the resin and introduces internal stresses in the composites. When curing at higher temperatures in order to shorten up the processing time, higher curing stresses and thermal...

  13. The influence of high and low temperatures on the impact properties of glass–epoxy composites

    Directory of Open Access Journals (Sweden)

    SLAVISA PUTIC

    2007-07-01

    Full Text Available The aim of this paper is to present the influence of high and low temperatures on the impact properties glass–epoxy composites. The impact strength an is presented for four different glass–epoxy composite structures at three different temperatures, i.e., at room temperature t = 20 °C, at an elevated temperature t = +50 °C and at a low temperature t = –50 °C. Standard mechanical testing was carried out on the composite materials with specific masses of reinforcement of 210 g m-2 and 550 g m-2 and orientations 0°/90° and ±45°. Micromechanical analysis of the failure was performed in order to determine real models and mechanisms of crack and temperature influence on the impact properties.

  14. Dissolved Organic Carbon Influences Microbial Community Composition and Diversity in Managed Aquifer Recharge Systems

    KAUST Repository

    Li, D.

    2012-07-13

    This study explores microbial community structure in managed aquifer recharge (MAR) systems across both laboratory and field scales. Two field sites, the Taif River (Taif, Saudi Arabia) and South Platte River (Colorado), were selected as geographically distinct MAR systems. Samples derived from unsaturated riverbed, saturated-shallow-infiltration (depth, 1 to 2 cm), and intermediate-infiltration (depth, 10 to 50 cm) zones were collected. Complementary laboratory-scale sediment columns representing low (0.6 mg/liter) and moderate (5 mg/liter) dissolved organic carbon (DOC) concentrations were used to further query the influence of DOC and depth on microbial assemblages. Microbial density was positively correlated with the DOC concentration, while diversity was negatively correlated at both the laboratory and field scales. Microbial communities derived from analogous sampling zones in each river were not phylogenetically significantly different on phylum, class, genus, and species levels, as determined by 16S rRNA gene pyrosequencing, suggesting that geography and season exerted less sway than aqueous geochemical properties. When field-scale communities derived from the Taif and South Platte River sediments were grouped together, principal coordinate analysis revealed distinct clusters with regard to the three sample zones (unsaturated, shallow, and intermediate saturated) and, further, with respect to DOC concentration. An analogous trend as a function of depth and corresponding DOC loss was observed in column studies. Canonical correspondence analysis suggests that microbial classes Betaproteobacteria and Gammaproteobacteria are positively correlated with DOC concentration. Our combined analyses at both the laboratory and field scales suggest that DOC may exert a strong influence on microbial community composition and diversity in MAR saturated zones.

  15. Influence of environmental variables on the structure and composition of soil bacterial communities in natural and constructed wetlands.

    Science.gov (United States)

    Arroyo, Paula; Sáenz de Miera, Luis E; Ansola, Gemma

    2015-02-15

    Bacteria are key players in wetland ecosystems, however many essential aspects regarding the ecology of wetland bacterial communities remain unknown. The present study characterizes soil bacterial communities from natural and constructed wetlands through the pyrosequencing of 16S rDNA genes in order to evaluate the influence of wetland variables on bacterial community composition and structure. The results show that the composition of soil bacterial communities was significantly associated with the wetland type (natural or constructed wetland), the type of environment (lagoon, Typha or Salix) and three continuous parameters (SOM, COD and TKN). However, no clear associations were observed with soil pH. Bacterial diversity values were significantly lower in the constructed wetland with the highest inlet nutrient concentrations. The abundances of particular metabolic groups were also related to wetland characteristics.

  16. Influence of the leaving group on the dynamics of a gas-phase SN2 reaction

    Science.gov (United States)

    Stei, Martin; Carrascosa, Eduardo; Kainz, Martin A.; Kelkar, Aditya H.; Meyer, Jennifer; Szabó, István; Czakó, Gábor; Wester, Roland

    2016-02-01

    In addition to the nucleophile and solvent, the leaving group has a significant influence on SN2 nucleophilic substitution reactions. Its role is frequently discussed with respect to reactivity, but its influence on the reaction dynamics remains unclear. Here, we uncover the influence of the leaving group on the gas-phase dynamics of SN2 reactions in a combined approach of crossed-beam imaging and dynamics simulations. We have studied the reaction F- + CH3Cl and compared it to F- + CH3I. For the two leaving groups, Cl and I, we find very similar structures and energetics, but the dynamics show qualitatively different features. Simple scaling of the leaving group mass does not explain these differences. Instead, the relevant impact parameters for the reaction mechanisms are found to be crucial and the differences are attributed to the relative orientation of the approaching reactants. This effect occurs on short timescales and may also prevail in solution-phase conditions.

  17. Influences of floral composition and environment on plant biomarkers across a Cretaceous landscape (Big Cedar Ridge)

    Science.gov (United States)

    Bush, R. T.; Diefendorf, A. F.; Wing, S. L.; McInerney, F. A.

    2013-12-01

    The Late Cretaceous fossil site at Big Cedar Ridge (BCR; late Campanian, 72.7 Ma), located in the Bighorn Basin, Wyoming, USA, contains a flora preserved in situ in a volcanic ash tuff over an organic-rich paleosol. The BCR flora is irregularly but extensively exposed along a ~4 km north-south transect and records a lowland flora that grew on a coastal delta on the western shore of the Cretaceous Interior Seaway (Meeteetse Formation). The transect spans a diverse landscape and a range of environmental gradients from very carbon-rich, swampy soils in the southern portion to less carbon-rich in the north; the landscape is also intersected by multiple inactive channel cuts that were filling with sediment and organic matter at the time of ash deposition. Recently Wing and others (2012, Ecological Monographs) described the composition of the local plant community at high resolution across the entire landscape, including identification and quantification of cover and richness for >122 taxonomic morphotypes, for each of 100 sites along the transect. Big Cedar Ridge captures an important time in the ecological development of plant communities: the site preserves ferns, gymnosperms, and angiosperms in 'fern thicket' floral assemblages, which are rare today, as well as disturbed habitats with abundant herbaceous 'dicot' angiosperms. During the Late Cretaceous angiosperms were globally increasing in abundance, displacing other plant groups as vegetational dominants. This setting allows for a novel analysis of plant biomarkers in the context of floral diversity, abundance, and landscape heterogeneity. We quantified leaf waxes (n-alkyl lipids), plant-derived terpenoids, bacterial hopanes, carbon isotope values (including bulk and compound-specific), and percent total organic carbon of the underlying paleosol for 36 sites along the transect in order to assess the influence of floral composition and soil environment on biomarker distributions and preservation. We compare lipid

  18. Five groups of red giants with distinct chemical composition in the globular cluster NGC 2808

    CERN Document Server

    Carretta, Eugenio

    2015-01-01

    The chemical composition of multiple populations in the massive globular cluster (GC) NGC~2808 is addressed with the homogeneous abundance re-analysis of 140 red giant branch (RGB) stars. UVES spectra for 31 stars and GIRAFFE spectra for the other giants were analysed with the same procedures used for about 2500 giants in 23 GCs in our FLAMES survey, deriving abundances of Fe, O, Na, Mg, Si, Ca, Ti, Sc, Cr, Mn, and Ni. Iron, elements from alpha-capture, and in the Fe-group do not show intrinsic scatter. On our UVES scale the metallicity of NGC~2808 is [Fe/H]=-1.129+/-0.005+/-0.034$ (+/-statistical +/-systematic error) with sigma=0.030 (31 stars). Main features related to proton-capture elements are retrieved, but the improved statistics and the smaller associated internal errors allow to uncover five distinct groups of stars along the Na-O anticorrelation. We observe large depletions in Mg, anticorrelated with enhancements of Na and also Si, suggestive of unusually high temperatures for proton-captures. About...

  19. Size of the group IVA iron meteorite core: Constraints from the age and composition of Muonionalusta

    CERN Document Server

    Moskovitz, Nicholas A

    2011-01-01

    The group IVA fractionally crystallized iron meteorites display a diverse range of metallographic cooling rates. These have been attributed to their formation in a metallic core, approximately 150 km in radius, that cooled to crystallization in the absence of any appreciable insulating mantle. Here we build upon this formation model by incorporating several new constraints. These include (i) a recent U-Pb radiometric closure age of <2.5 Myr after solar system formation for the group IVA iron Muonionalusta, (ii) new measurements and modeling of highly siderophile element compositions for a suite of IVAs, and (iii) consideration of the thermal effects of heating by the decay of the short-lived radionuclide 60Fe. Our model for the thermal evolution of the IVA core suggests that it was approximately 50 - 110 km in radius after being collisionally exposed. This range is due to uncertainties in the initial abundance of live 60Fe incorporated into the IVA core. Our models define a relationship between cooling rat...

  20. Influence of pre-heat treatment and different light-curing units on Vickers hardness of a microhybrid composite resin

    Science.gov (United States)

    Saade, E. G.; Bandeca, M. C.; Rastelli, A. N. S.; Bagnato, V. S.; Porto-Neto, S. T.

    2009-06-01

    The aim of this study was to evaluate the hardness of a dental composite resin submitted to temperature changes before photo-activation with two light-curing unite (LCUs). Five samples (4 mm in diameter and 2 mm in thickness) for each group were made with pre-cure temperatures of 37, 54, and 60°C. The samples were photo-activated with a conventional quartz-tungsten-halogen (QTH) and blue LED LCUs during 40 s. The hardness Vickers test (VHN) was performed on the top and bottom surfaces of the samples. According to the interaction between light-curing unit and different pre-heating temperatures of composite resin, only the light-curing unit provided influences on the mean values of initial Vickers hardness. The light-curing unit based on blue LED showed hardness mean values more homogeneous between the top and bottom surfaces. The hardness mean values were not statistically significant difference for the pre-cure temperature used. According to these results, the pre-heating of the composite resin provide no influence on Vickers hardness mean values, however the blue LED showed a cure more homogeneous than QTH LCU.

  1. Influence of nanometer scale particulate fillers on some properties of microfilled composite resin.

    Science.gov (United States)

    Garoushi, Sufyan; Lassila, Lippo V J; Vallittu, Pekka K

    2011-07-01

    The aim of this study was to evaluate the effect of different weight fractions of nanometer sized particulate filler on properties of microfilled composite resin. Composite resin was prepared by mixing 33 wt% of resin matrix to the 67 wt% of silane treated microfine silica particulate fillers with various fractions of nanometer sized fillers (0, 10, 15, 20, 30 wt%) using a high speed mixing machine. Test specimens made of the composites were tested with a three-point bending test with a speed of 1.0 mm/min until fracture. Surface microhardess (Vicker's microhardness) was also determined. The volumetric shrinkage in percent was calculated as a buoyancy change in distilled water by means of the Archimedes principle. The degree of monomer conversion (DC%) of the experimental composites containing different nanofiller fractions was measured using FTIR spectroscopy. Surface roughness (Ra) was determined using a surface profilometer. Nanowear measurements were carried out using a nanoindentation device. The water uptake of specimens was also measured. Parameters were statistically analysed by ANOVA (P < 0.05). The group without nanofillers showed the highest flexural strength and modulus, DC% and Ra value. The group with 30% nanofillers had the highest water uptake and volumetric shrinkage. No significant difference was found in Vicker's microhardness and the nanowear of the composites. The plain microfilled composite demonstrated superior properties compared to the composites loaded with nanofillers with the exception of surface roughness.

  2. Tall fescue cultivar and fungal endophyte combinations influence plant growth and root exudate composition.

    Science.gov (United States)

    Guo, Jingqi; McCulley, Rebecca L; McNear, David H

    2015-01-01

    Tall fescue [Lolium arundinaceum (Schreb.)] is a cool-season perennial grass used in pastures throughout the Southeastern United States. The grass can harbor a shoot-specific fungal endophyte (Epichloë coenophiala) thought to provide the plant with enhanced resistance to biotic and abiotic stresses. Because alkaloids produced by the common variety of the endophyte cause severe animal health issues, focus has been on replacing the common-toxic strain with novel varieties that do not produce the mammal-toxic alkaloids but maintain abiotic and biotic stress tolerance benefits. Little attention has been given to the influence of the plant-fungal symbiosis on rhizosphere processes. Therefore, our objective was to study the influence of this relationship on plant biomass production and root exudate composition in tall fescue cultivars PDF and 97TF1, which were either not infected with the endophyte (E-), infected with the common toxic endophyte (CTE+) strain or with one of two novel endophytes (AR542E+, AR584E+). Plants were grown sterile for 3 weeks after which plant biomass, total organic carbon, total phenolic content and detailed chemical composition of root exudates were determined. Plant biomass production and exudate phenolic and organic carbon content were influenced by endophyte status, tall fescue cultivar, and their interaction. GC-TOF MS identified 132 compounds, including lipids, carbohydrates and carboxylic acids. Cluster analysis showed that the interaction between endophyte and cultivar resulted in unique exudate profiles. This is the first detailed study to assess how endophyte infection, notably with novel endophytes, and tall fescue cultivar interact to influence root exudate composition. Our results illustrate that tall fescue cultivar and endophyte status can influence plant growth and root exudate composition, which may help explain the observed influence of this symbiosis on rhizosphere biogeochemical processes.

  3. Tall fescue cultivar and fungal endophyte combinations influence plant growth and root exudate composition

    Directory of Open Access Journals (Sweden)

    Jingqi eGuo

    2015-04-01

    Full Text Available Tall fescue (Lolium arundinaceum (Schreb. is a cool-season perennial grass used in pastures throughout the Southeastern United States. The grass can harbor a shoot-specific fungal endophyte (Epichloë coenophiala thought to provide the plant with enhanced resistance to biotic and abiotic stresses. Because alkaloids produced by the common variety of the endophyte cause severe animal health issues, focus has been on replacing the common-toxic strain with novel varieties that do not produce the mammal-toxic alkaloids but maintain abiotic and biotic stress tolerance benefits. Little attention has been given to the influence of the plant-fungal symbiosis on rhizosphere processes. Therefore, our objective was to study the influence of this relationship on plant biomass production and root exudate composition in tall fescue cultivars PDF and 97TF1, which were either not infected with the endophyte (E-, infected with the common toxic endophyte (CTE+ strain or with one of two novel endophytes (AR542E+, AR584E+. Plants were grown sterile for three weeks after which plant biomass, total organic carbon, total phenolic content and detailed chemical composition of root exudates were determined. Plant biomass production and exudate phenolic and organic carbon content were influenced by endophyte status, tall fescue cultivar, and their interaction. GC-TOF MS identified 132 compounds, including lipids, carbohydrates and carboxylic acids. Cluster analysis showed that the interaction between endophyte and cultivar resulted in unique exudate profiles. This is the first detailed study to assess how endophyte infection, notably with novel endophytes, and tall fescue cultivar interact to influence root exudate composition. Our results illustrate that tall fescue cultivar and endophyte status can influence plant growth and root exudate composition, which may help explain the observed influence of this symbiosis on rhizosphere biogeochemical processes.

  4. Characterization and Leach Testing for PUREX Cladding Waste Sludge (Group 3) and REDOX Cladding Waste Sludge (Group 4) Actual Waste Sample Composites

    Energy Technology Data Exchange (ETDEWEB)

    Snow, Lanee A.; Buck, Edgar C.; Casella, Amanda J.; Crum, Jarrod V.; Daniel, Richard C.; Draper, Kathryn E.; Edwards, Matthew K.; Fiskum, Sandra K.; Jagoda, Lynette K.; Jenson, Evan D.; Kozelisky, Anne E.; MacFarlan, Paul J.; Peterson, Reid A.; Swoboda, Robert G.

    2009-02-13

    A testing program evaluating actual tank waste was developed in response to Task 4 from the M-12 External Flowsheet Review Team (EFRT) issue response plan.(a) The testing program was subdivided into logical increments. The bulk water-insoluble solid wastes that are anticipated to be delivered to the Waste Treatment and Immobilization Plant (WTP) were identified according to type such that the actual waste testing could be targeted to the relevant categories. Eight broad waste groupings were defined. Samples available from the 222S archive were identified and obtained for testing. The actual wastetesting program included homogenizing the samples by group, characterizing the solids and aqueous phases, and performing parametric leaching tests. Two of the eight defined groups—plutonium-uranium extraction (PUREX) cladding waste sludge (Group 3, or CWP) and reduction-oxidation (REDOX) cladding waste sludge (Group 4, or CWR)—are the subjects of this report. Both the Group 3 and 4 waste composites were anticipated to be high in gibbsite, requiring caustic leaching. Characterization of the composite Group 3 and Group 4 waste samples confirmed them to be high in gibbsite. The focus of the Group 3 and 4 testing was on determining the behavior of gibbsite during caustic leaching. The waste-type definition, archived sample conditions, homogenization activities, characterization (physical, chemical, radioisotope, and crystal habit), and caustic leaching behavior as functions of time, temperature, and hydroxide concentration are discussed in this report. Testing was conducted according to TP-RPP-WTP-467.

  5. Health information, credibility, homophily, and influence via the Internet: Web sites versus discussion groups.

    Science.gov (United States)

    Wang, Zuoming; Walther, Joseph B; Pingree, Suzanne; Hawkins, Robert P

    2008-07-01

    Despite concerns about online health information and efforts to improve its credibility, how users evaluate and utilize such information presented in Web sites and online discussion groups may involve different evaluative mechanisms. This study examined credibility and homophily as two underlying mechanisms for social influence with regard to online health information. An original experiment detected that homophily grounded credibility perceptions and drove the persuasive process in both Web sites and online discussion groups. The more homophilous an online health information stimulus was perceived as being, the more likely people were to adopt the advice offered in that particular piece of information.

  6. Topological influence and excitations: decomposition formulas for calculating homotopy groups of symmetry broken phases

    CERN Document Server

    Higashikawa, Sho

    2016-01-01

    A symmetry broken phase of a system with internal degrees of freedom often features a complex order parameter, which generates a rich variety of topological excitations and topological influence between them, yet the very complexity of the order parameter makes it difficult to treat topological excitations and topological influence in a unified manner. To overcome this problem, we develop a general method to calculate homotopy groups and derive decomposition formulas which express homotopy groups of a quotient space $G/H$ in terms of those of the symmetry $G$ of the system and those of the remaining symmetry $H$ of the state. We apply these formulas to analyze a general monopole and a general three-dimensional skyrmion, and show that their textures are obtained through substitution of the corresponding $\\mathfrak{su}(2)$-subalgebra for the $\\mathfrak{su}(2)$-spin. We also show that a discrete symmetry of $H$ is necessary for the presence of topological influence and find the topological influence on a skyrmio...

  7. The Influence of Older Age Groups to Sustainable Product Design Research of Urban Public Facilities

    Science.gov (United States)

    Wen-juan, Zhang; Hou-peng, Song

    2017-01-01

    Through summarize the status quo of public facilities design to older age groups in China and a variety of factors what influence on them, the essay, from different perspective, is designed to put forward basic principle to sustainable design of public facilities for the aged in the city, and thus further promote and popularize the necessity of sustainable design applications in the future design of public facilities for elderly people.

  8. Group Projects in Social Work Education: The Influence of Group Characteristics and Moderators on Undergraduate Student Outcomes

    Science.gov (United States)

    Postlethwait, Ariana E.

    2016-01-01

    This study examined the impact of group size, group formation, group conflict, and division of labor on student outcomes in a group project for a sample of 112 BSW research seminar students at a large university in the Midwest. Students completed surveys on their experiences with the group project at the end of the semester. Multiple regression…

  9. Body composition and somatotype of judo athletes and untrained male students as a reference group for comparison in sport

    Directory of Open Access Journals (Sweden)

    Buśko Krzysztof

    2017-02-01

    Full Text Available Study aim: The aim of this study was to determine the body composition and somatotype of untrained male students studying at Warsaw University of Technology in 2011, in order to create a current reference group for comparison, and to investigate the difference in body build of male judoists compared with the non-athlete group.

  10. The Impacts of Friendship Groups' Racial Composition When Perceptions of Prejudice Threaten Students' Academic Self-Concept

    Science.gov (United States)

    Lehman, Brett

    2012-01-01

    Literature on racially prejudiced stereotypes suggests that students' academic self-concepts (ASC) can be damaged when a stereotype demeans the intelligence of their racial or ethnic group. There is little research on how students overcome this burden, but there is some evidence that the racial composition of friendship groups play a role. One…

  11. Stomatal cell wall composition: distinctive structural patterns associated with different phylogenetic groups.

    Science.gov (United States)

    Shtein, Ilana; Shelef, Yaniv; Marom, Ziv; Zelinger, Einat; Schwartz, Amnon; Popper, Zoë A; Bar-On, Benny; Harpaz-Saad, Smadar

    2017-04-01

    Stomatal morphology and function have remained largely conserved throughout ∼400 million years of plant evolution. However, plant cell wall composition has evolved and changed. Here stomatal cell wall composition was investigated in different vascular plant groups in attempt to understand their possible effect on stomatal function. A renewed look at stomatal cell walls was attempted utilizing digitalized polar microscopy, confocal microscopy, histology and a numerical finite-elements simulation. The six species of vascular plants chosen for this study cover a broad structural, ecophysiological and evolutionary spectrum: ferns ( Asplenium nidus and Platycerium bifurcatum ) and angiosperms ( Arabidopsis thaliana and Commelina erecta ) with kidney-shaped stomata, and grasses (angiosperms, family Poaceae) with dumbbell-shaped stomata ( Sorghum bicolor and Triticum aestivum ). Three distinct patterns of cellulose crystallinity in stomatal cell walls were observed: Type I (kidney-shaped stomata, ferns), Type II (kidney-shaped stomata, angiosperms) and Type III (dumbbell-shaped stomata, grasses). The different stomatal cell wall attributes investigated (cellulose crystallinity, pectins, lignin, phenolics) exhibited taxon-specific patterns, with reciprocal substitution of structural elements in the end-walls of kidney-shaped stomata. According to a numerical bio-mechanical model, the end walls of kidney-shaped stomata develop the highest stresses during opening. The data presented demonstrate for the first time the existence of distinct spatial patterns of varying cellulose crystallinity in guard cell walls. It is also highly intriguing that in angiosperms crystalline cellulose appears to have replaced lignin that occurs in the stomatal end-walls of ferns serving a similar wall strengthening function. Such taxon-specific spatial patterns of cell wall components could imply different biomechanical functions, which in turn could be a consequence of differences in

  12. Palaeoenvironmental drivers of vertebrate community composition in the Belly River Group (Campanian) of Alberta, Canada, with implications for dinosaur biogeography.

    Science.gov (United States)

    Cullen, Thomas M; Evans, David C

    2016-11-15

    The Belly River Group of southern Alberta is one of the best-sampled Late Cretaceous terrestrial faunal assemblages in the world. This system provides a high-resolution biostratigraphic record of terrestrial vertebrate diversity and faunal turnover, and it has considerable potential to be a model system for testing hypotheses of dinosaur palaeoecological dynamics, including important aspects of palaeoecommunity structure, trophic interactions, and responses to environmental change. Vertebrate fossil microsites (assemblages of small bones and teeth concentrated together over a relatively short time and thought to be representative of community composition) offer an unparalleled dataset to better test these hypotheses by ameliorating problems of sample size, geography, and chronostratigraphic control that hamper other palaeoecological analyses. Here, we assembled a comprehensive relative abundance dataset of microsites sampled from the entire Belly River Group and performed a series of analyses to test the influence of environmental factors on site and taxon clustering, and assess the stability of faunal assemblages both temporally and spatially. We also test the long-held idea that populations of large dinosaur taxa were particularly sensitive to small-scale environmental gradients, such as the paralic (coastal) to alluvial (inland) regimes present within the time-equivalent depositional basin of the upper Oldman and lower Dinosaur Park Formations. Palaeoenvironment (i.e. reconstructed environmental conditions, related to relative amount of alluvial, fluvial, and coastal influence in associated sedimentary strata) was found to be strongly associated with clustering of sites by relative-abundance faunal assemblages, particularly in relation to changes in faunal assemblage composition and marine-terrestrial environmental transitions. Palaeogeography/palaeolandscape were moderately associated to site relative abundance assemblage clustering, with depositional setting

  13. Group management influences reproductive function of the male cheetah (Acinonyx jubatus).

    Science.gov (United States)

    Koester, Diana C; Freeman, Elizabeth W; Wildt, David E; Terrell, Kimberly A; Franklin, Ashley D; Meeks, Karen; Crosier, Adrienne E

    2015-09-21

    Although the free-ranging cheetah is generally socially solitary, as many as 60% of males live in same-sex (usually sibling) coalitions. Under ex situ conditions, the cheetah experiences low reproductive success with only ~18% of males having ever produced young. Most male cheetahs (85%) are managed in captivity in coalitions, but with no data on the influence of social grouping on reproductive parameters. We examined the influence of singleton versus coalition management on various male cheetah physiological traits, including ejaculate quality and gonadal and adrenal hormone metabolite concentrations. We also assessed behaviour within coalitions for evidence of social hierarchy through initiation of interactions with group mates and relatedness to physiological traits. Ejaculate quality (including total motile and structurally normal spermatozoa per ejaculate) and androgen concentration profiles were higher (P cheetah, specifically related to the development of normal, motile spermatozoa and androgen production, is influenced by management with same-sex conspecifics. The findings have implications for ex situ conservation breeding programs by suggesting that reproductive quality can be enhanced through group maintenance of cheetah males.

  14. Influence of finishing/polishing on color stability and surface roughness of composites submitted to accelerated artificial aging

    Directory of Open Access Journals (Sweden)

    Gustavo Da Col dos Santos Pinto

    2013-01-01

    Full Text Available Aim: To assess the influence of finishing/polishing procedure on color stability (ΔE and surface roughness (Ra of composites (Heliomolar and Tetric - color A2 submitted to accelerated artificial aging (AAA. Materials and Methods : Sixty test specimens were made of each composite (12 mm × 2 mm and separated into six groups (n = 10, according to the type of finishing/polishing to which they were submitted: C, control; F, tip 3195 F; FF, tip 3195 FF; FP, tip 3195 F + diamond paste; FFP, tip 3195 FF + diamond paste; SF, Sof-Lex discs. After polishing, controlled by an electromechanical system, initial color (spectrophotometer PCB 6807 BYK GARDNER and Ra (roughness meter Surfcorder SE 1700, cut-off 0.25 mm readings were taken. Next, the test specimens were submitted to the AAA procedure (C-UV Comexim for 384 hours, and at the end of this period, new color readings and R a were taken. Results: Statistical analysis [2-way analysis of variance (ANOVA, Bonferroni, P < 0.05] showed that all composites demonstrated ΔE alteration above the clinically acceptable limits, with the exception of Heliomolar composite in FP. The greatest ΔE alteration occurred for Tetric composite in SF (13.38 ± 2.10 statistically different from F and FF (P < 0.05. For Ra , Group F showed rougher samples than FF with statistically significant difference (P < 0.05. Conclusion: In spite of the surface differences, the different finishing/polishing procedures were not capable of providing color stability within the clinically acceptable limits.

  15. The Influence of Nanofillers on the Mechanical Properties of Carbon Fibre Reinforced Methyl Methacrylate Composite

    Directory of Open Access Journals (Sweden)

    Tomas ŽUKAS

    2012-09-01

    Full Text Available The influence of different types of nanofillers – carbon nanotubes (CNT and organically modified nanoclay – on the flexural properties and nail penetration resistance of carbon fiber reinforced methyl methacrylate (MMA composite have been investigated. An ultrasonic mixing was used to distribute various content of nanofillers (0.7 wt.% – 3.0 wt.% in MMA resin. Scanning electron microscopy and X-ray diffraction analyses confirmed formation of intercalated MMA clay nanocomposites. Two different stacking sequences, [0/90]3 or [0/90/45]2, and two types of carbon fibre, with or without epoxy binder, were used for composites preparation. The composites with stacking sequence of [0/90]3 show higher resistance to the mechanical loading. Epoxy binder increases fibre adhesion interaction with MMA resin, however, almost does not influences on the fibre reinforced composite strength properties. The results demonstrated that only low content (up to 1 wt.% of organically modified nanoclay Cloisite 10A increases the carbon fibre reinforced composites resistance to flexure and nail penetration. The low content of CNT also increases flexural stress and modulus, but decreases resistance to the nail penetration.DOI: http://dx.doi.org/10.5755/j01.ms.18.3.2434

  16. Influence of artificial ageing on surface properties and Streptococcus mutans adhesion to dental composite materials.

    Science.gov (United States)

    Hahnel, Sebastian; Henrich, Anne; Rosentritt, Martin; Handel, Gerhard; Bürgers, Ralf

    2010-02-01

    The aim of this in vitro study was to investigate the influence of artificial ageing on the surface properties and early Streptococcus mutans adhesion to current dental composites for the direct restoration of class II defects. Three hundred and thirty specimens each were prepared from five dental composites, and were randomly allotted to various artificial ageing protocols (storage in distilled water/ethanol/artificial saliva for 7/90/365 days; thermal cycling, 6,000 cycles 5/55 degrees C). Prior and after each treatment, surface roughness (R(a)) and hydrophobicity were determined, and S. mutans adhesion (ATCC 25175; 2.5 h, 37 degrees C) was simulated with and without prior exposition to human whole saliva (2 h, 37 degrees C). Adherence of S. mutans was determined fluorometrically. Means and standard deviations were calculated, and analyzed using three-way ANOVA and post-hoc analysis (alpha = 0.05). For both R(a) and S. mutans adherence to uncoated and saliva-coated specimens, significant influences of the composite material, the ageing medium and the ageing duration have been observed; for surface hydrophobicity, significant influences of the composite material and the ageing duration were found. For uncoated specimens, significant increases in S. mutans adhesion were observed with prolonged artificial ageing, whereas significant decreases in S. mutans adhesion were found for the saliva-coated specimens. The data indicate influences of the artificial ageing method on surface parameters such as R(a) and hydrophobicity as well as microbial adhesion. The results underline the relevance of saliva coating on the outcome of studies simulating microbial adhesion, and highlight differences in the susceptibility of dental composites for the adhesion of oral bacteria.

  17. The influence of group decision making on indecisiveness-related decisional confidence

    Directory of Open Access Journals (Sweden)

    Andrea L. Patalano

    2011-02-01

    Full Text Available Indecisiveness is an individual difference measure of chronic difficulty and delay in decision making. Indecisiveness is associated with low decisional confidence and distinct patterns of pre-choice information search behavior. The present study explored whether the confidence levels and search behaviors associated with individual indecisiveness also emerge in group decision making contexts. In this study, 97 decisive and indecisive participants were assigned to make a decision individually or in a homogenous three-person group. Indecisiveness score was found to predict participant decisional confidence in the individual condition but not in the group condition, with group participants being overall more confident than individuals. Similar results were obtained for other related measures of participants' perceptions of the decision task. Surprisingly, no indecisiveness-related differences in information search were found, suggesting that other aspects of the group process contribute to increased confidence. The results provide initial evidence that indecisiveness does not influence group decision making and that, especially for indecisive individuals, working in groups may be a way to boost decisional confidence.

  18. Hygrothermal effects on fiber reinforced polyphenylene sulphide composites : humidity uptake and temperature influence on mechanical properties of glass and carbon fiber reinforced polyphenylene sulphide composites

    OpenAIRE

    Suárez Cabrera, Emmanuel

    2011-01-01

    In the ever-continuing quest for greener and cheaper aerospace materials, the Durability Group, part of the Design and Production of Composite Structures Department at the faculty of Aerospace Engineering of the Delft University of Technology is focusing on the use of new thermoplastic composites for aerospace structures. Currently the introduction of Nylon composites in the aerospace industry is being investigated. Nylon as a thermoplastic matrix for fibre reinforced composites can be bought...

  19. Nitrogen forms influence microcystin concentration and composition via changes in cyanobacterial community structure.

    Directory of Open Access Journals (Sweden)

    Marie-Eve Monchamp

    Full Text Available The eutrophication of freshwaters is a global health concern as lakes with excess nutrients are often subject to toxic cyanobacterial blooms. Although phosphorus is considered the main element regulating cyanobacterial biomass, nitrogen (N concentration and more specifically the availability of different N forms may influence the overall toxicity of blooms. In this study of three eutrophic lakes prone to cyanobacterial blooms, we examined the effects of nitrogen species and concentrations and other environmental factors in influencing cyanobacterial community structure, microcystin (MC concentrations and MC congener composition. The identification of specific MC congeners was of particular interest as they vary widely in toxicity. Different nitrogen forms appeared to influence cyanobacterial community structure leading to corresponding effects on MC concentrations and composition. Total MC concentrations across the lakes were largely explained by a combination of abiotic factors: dissolved organic nitrogen, water temperature and ammonium, but Microcystis spp. biomass was overall the best predictor of MC concentrations. Environmental factors did not appear to affect MC congener composition directly but there were significant associations between specific MC congeners and particular species. Based on redundancy analyses (RDA, the relative biomass of Microcystis aeruginosa was associated with MC-RR, M. wesenbergii with MC-LA and Aphanizomenon flos-aquae with MC-YR. The latter two species are not generally considered capable of MC production. Total nitrogen, water temperature, ammonium and dissolved organic nitrogen influenced the cyanobacterial community structure, which in turn resulted in differences in the dominant MC congener and the overall toxicity.

  20. Nitrogen forms influence microcystin concentration and composition via changes in cyanobacterial community structure.

    Science.gov (United States)

    Monchamp, Marie-Eve; Pick, Frances R; Beisner, Beatrix E; Maranger, Roxane

    2014-01-01

    The eutrophication of freshwaters is a global health concern as lakes with excess nutrients are often subject to toxic cyanobacterial blooms. Although phosphorus is considered the main element regulating cyanobacterial biomass, nitrogen (N) concentration and more specifically the availability of different N forms may influence the overall toxicity of blooms. In this study of three eutrophic lakes prone to cyanobacterial blooms, we examined the effects of nitrogen species and concentrations and other environmental factors in influencing cyanobacterial community structure, microcystin (MC) concentrations and MC congener composition. The identification of specific MC congeners was of particular interest as they vary widely in toxicity. Different nitrogen forms appeared to influence cyanobacterial community structure leading to corresponding effects on MC concentrations and composition. Total MC concentrations across the lakes were largely explained by a combination of abiotic factors: dissolved organic nitrogen, water temperature and ammonium, but Microcystis spp. biomass was overall the best predictor of MC concentrations. Environmental factors did not appear to affect MC congener composition directly but there were significant associations between specific MC congeners and particular species. Based on redundancy analyses (RDA), the relative biomass of Microcystis aeruginosa was associated with MC-RR, M. wesenbergii with MC-LA and Aphanizomenon flos-aquae with MC-YR. The latter two species are not generally considered capable of MC production. Total nitrogen, water temperature, ammonium and dissolved organic nitrogen influenced the cyanobacterial community structure, which in turn resulted in differences in the dominant MC congener and the overall toxicity.

  1. Influence of flowable materials on microleakage of nanofilled and hybrid Class II composite restorations with LED and QTH LCUs

    Directory of Open Access Journals (Sweden)

    Sadeghi Mostafa

    2009-01-01

    Full Text Available Background: Class II composite restorations are more frequently being placed with margins apical to the cementoenamel junction (CEJ and margins within the dentin are prone to microleakage. Aims: This in vitro study was used to evaluate the influence of flowable composite and flowable compomer as gingival liner on microleakage in Class II composite restorations and compare a light-emitting diode (LED unit with a quartz tungsten halogen (QTH unit for light-activating composite resins. Materials and Methods: Mesioocclusal and distoocclusal Class II cavity preparations were made in 72 sound extracted premolars. The buccolingual width was 2.5 mm and the gingival margins of all the cavities were placed 1.0 mm apical to the CEJ. The boxes were prepared 1.5 mm deep axially, making 144 slot cavities. Teeth were randomly divided into the following two groups (n = 72: (I Universal Filtek Supreme XT; Universal Filtek Supreme XT + Flwable Filtek XT and Universal Filtek Supreme XT + Dyract Flow and (II Filtek Z250; Filtek Z250 + Flwable Filtek XT and Filtek Z250 + Dyract Flow. Flowable materials were injected into the gingival floor of the cavity to a thickness of 1.0 mm. Each increment was cured for 20 s. One-half of the subgroups in each group were cured with QTH and the other half with LED light curing units (LCUs. After 1 week of incubation at 37°C, the specimens were thermocycled (5-55°C, x1500, immersed in 0.5% basic fuchsine dye for 24 h and sectioned and microleakage was evaluated at the gingival margin by two examiners using a 0-3 score scale. The data were analyzed using the Kruskal-Wallis and Mann-Whitney U tests. Results: The groups utilizing flowable liners had significantly less microleakage (P < 0.05. No significant difference was identified between Universal Filtek Supreme XT and Filtek Z250 composites with and without flowable materials. There was no significant between utilizing flowable composite or flowable compomer and between each

  2. Microstructural Influence on Deformation and Fatigue Life of Composites Using the Generalized Method of Cells

    Science.gov (United States)

    Arnold, S. M.; Murthy, P.; Bednarcyk, B. A.; Pineda, E. J.

    2015-01-01

    A fully coupled deformation and damage approach to modeling the response of composite materials and composite laminates is presented. It is based on the semi-­-analytical generalized method of cells (GMC) micromechanics model as well as its higher fidelity counterpart, HFGMC, both of which provide closed-form constitutive equations for composite materials as well as the micro scale stress and strain fields in the composite phases. The provided constitutive equations allow GMC and HFGMC to function within a higher scale structural analysis (e.g., finite element analysis or lamination theory) to represent a composite material point, while the availability of the micro fields allow the incorporation of lower scale sub­-models to represent local phenomena in the fiber and matrix. Further, GMC's formulation performs averaging when applying certain governing equations such that some degree of microscale field accuracy is surrendered in favor of extreme computational efficiency, rendering the method quite attractive as the centerpiece in a integrated computational material engineering (ICME) structural analysis; whereas HFGMC retains this microscale field accuracy, but at the price of significantly slower computational speed. Herein, the sensitivity of deformation and the fatigue life of graphite/epoxy PMC composites, with both ordered and disordered microstructures, has been investigated using this coupled deformation and damage micromechanics based approach. The local effects of fiber breakage and fatigue damage are included as sub-models that operate on the microscale for the individual composite phases. For analysis of laminates, classical lamination theory is employed as the global or structural scale model, while GMC/HFGMC is embedded to operate on the microscale to simulate the behavior of the composite material within each laminate layer. A key outcome of this study is the statistical influence of microstructure and micromechanics idealization (GMC or HFGMC) on

  3. The Influence Of The Temperature Of Liquid Nitrogen On The Physical Properties Of Powder Magnetic Composites

    Directory of Open Access Journals (Sweden)

    Kapelski D.

    2015-06-01

    Full Text Available The paper presents the physical properties of soft magnetic iron composites and Nd-Fe-B bonded permanent magnets measured at room temperature and at liquid nitrogen. The objective of research was a determination of influence of liquid nitrogen temperature on the magnetic properties, resistivity and mechanical properties of different powder magnetic materials. Research was carried out for three powder materials: soft magnetic, i.e. Somaloy 700, AncorLam and hard magnetic powder MQP-B used for production of bonded magnets. Composite specimens were prepared by compression moulding technology.

  4. Influence of Glass Powder on Hydration Kinetics of Composite Cementitious Materials

    Directory of Open Access Journals (Sweden)

    Xiaolin Chang

    2015-01-01

    Full Text Available The influence of glass powder (GP on hydration kinetics of composite cementitious materials has been investigated by isothermal calorimetry test and hydration kinetics methods in this paper. The hydration heat emission rate and hydration heat decrease gradually while the induction and acceleration period increase with the increase of GP content. According to Krstulovic-Dabic model, the hydration process of composite cementitious materials containing GP is controlled by a variety of complicated reaction mechanisms, which can be divided into three periods: nucleation and crystal growth (NG, phase boundary reaction (I, and diffusion (D. The NG and I process are shortened after incorporating GP.

  5. The influence of the silicate slag composition on copper losses during smelting of the sulfide concentrates

    Directory of Open Access Journals (Sweden)

    Živković Živan

    2009-01-01

    Full Text Available This paper presents the results of multi-linear regression analysis (MLRA of the slag composition (SiO2, FeO, Fe3O4, CaO, Al2O3 and the content of copper in the matte on resulting copper content in the slag during smelting of the sulfide concentrates in the reverberatory furnace. When comparing results obtained with MLRA model calculations with values measured at industrial level high degree of fitting is obtained (R2 = 0.974. This indicates that slag composition and content of copper in the matte influences the copper losses in the waste slag with the probability of 95 %.

  6. Influence of composition on the adhesive strength and initial viscosity of denture adhesives.

    Science.gov (United States)

    Han, Jian-min; Hong, Guang; Hayashida, Kentaro; Maeda, Takeshi; Murata, Hiroshi; Sasaki, Keiichi

    2014-01-01

    To investigate the effect of composition on the initial viscosity and adhesive strength between denture adhesives and the denture base. Two types of water-soluble polymers (methoxy ethylene maleic anhydride copolymer [PVM-MA] and sodium carboxymethyl cellulose [CMC]) were used. Samples were divided into three groups. Group 1 contained only PVM-MA; Group 2 contained only CMC; and Group 3 contained PVM-MA and CMC. The initial viscosity and adhesive strength were measured. For Group 1, the initial viscosity increased significantly as PVM-MA content increased. The adhesive strength of Group 1 lasted longer than Group 2. The adhesive strength of Group 3 varied greatly. The ratio of CMC and PVM-MA has a significant effect on the initial viscosity and adhesive strength of denture adhesives. Our results suggest that it is possible to improve the durability of a denture adhesive by combining different water-soluble polymers.

  7. The influence of pre-Slavic ethnic groups on the hydronymy of present-day Slovakia

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    Jaromír Krško

    2015-12-01

    Full Text Available In this paper, we focus on the influence of pre-Slavic ethnic groups on the hydronymy of present-day Slovakia. The migration of entire ethnic groups – especially after the dissolution of the Roman Empire – led to contact between native and incoming people. Ethnic contact also affected languages of these ethnic groups, as mutual influencing and borrowing of vocabulary occurred. Incoming ethnic groups had to find their way around in the new surroundings as well as identify and distinguish important landmarks, mainly hills, mountains and streams. We can approach the issue of pre-Slavic hydronyms from two points of view: one, by analyzing the names preserved from the time period before the arrival of Slavs in the territory of Slovakia, and two, by analyzing the names whose origin some authors consider to be pre-Slavic. The oldest name of a river from the Slovak region comes from the time period before the arrival of the Slavs. It was recorded by the Roman emperor Marcus Aurelius in years 166–180 AD as Granoua. It is a record of the river Hron at which Roman legions fought against the Germanic tribes of the Marcomanni and Quadi. Several historians and linguists believe that besides the rivers Dunaj, Morava and Tisa, other names of big rivers date from before the arrival of Slavs in the central Europe. In the paper, we analyse the names Dunaj, Morava, Váh, Hron, Tisa, Nitra and Hornád.

  8. Influence of surface preparation on fracture load of resin composite-based repairs

    Science.gov (United States)

    Mateos-Palacios, Rocío; Román-Rodríguez, Juan-Luis; Solá-Ruíz, María-Fernanda; Fons-Font, Antonio

    2015-01-01

    The purpose of the present study is to evaluate the fracture load of composite-based repairs to fractured zirconium oxide (Z) crowns and to ceramic-fused-to-metal (CM) crowns, comparing different mechanical surface preparation methods. A total of 75 crowns were repaired; samples then underwent dynamic loading and thermocycling. Final fracture load values for failure of the repaired crowns were measured and the type of fracture registered. Group I: CM: Surface preparation with a diamond bur + 9.5% Hydrofluoric Acid (HF) etching; Group II): CM: air-particle (Al2O3) + 9.5% HF; Group III: CM: Silica coating (SiO2); Group IV): Z: air-particle (Al2O3) + HF 9.5%; Group V) Z: Silica coating (SiO2). Of the three CM groups, Group I (CM-diamond bur) showed the highest mean failure value, with significant difference in comparison with Group III (CM-silica coating). For the zirconia groups, the highest value was obtained by Group V (silica coating). Key words:Crown, ceramic-fused-to-metal, zirconia, resin-composite, ceramic covering. PMID:25810848

  9. Influence of surface preparation on fracture load of resin composite-based repairs.

    Science.gov (United States)

    Agustín-Panadero, Rubén; Mateos-Palacios, Rocío; Román-Rodríguez, Juan-Luis; Solá-Ruíz, María-Fernanda; Fons-Font, Antonio

    2015-02-01

    The purpose of the present study is to evaluate the fracture load of composite-based repairs to fractured zirconium oxide (Z) crowns and to ceramic-fused-to-metal (CM) crowns, comparing different mechanical surface preparation methods. A total of 75 crowns were repaired; samples then underwent dynamic loading and thermocycling. Final fracture load values for failure of the repaired crowns were measured and the type of fracture registered. Group I: CM: Surface preparation with a diamond bur + 9.5% Hydrofluoric Acid (HF) etching; Group II): CM: air-particle (Al2O3) + 9.5% HF; Group III: CM: Silica coating (SiO2); Group IV): Z: air-particle (Al2O3) + HF 9.5%; Group V) Z: Silica coating (SiO2). Of the three CM groups, Group I (CM-diamond bur) showed the highest mean failure value, with significant difference in comparison with Group III (CM-silica coating). For the zirconia groups, the highest value was obtained by Group V (silica coating). Key words:Crown, ceramic-fused-to-metal, zirconia, resin-composite, ceramic covering.

  10. Flavor Release Perception of Custard Desserts: Influence of Food Composition and Oral Parameters

    NARCIS (Netherlands)

    Ruth, van S.M.; Uriarte, A.R.; Aprea, E.; Sheehan, E.

    2008-01-01

    The influence of oral processing on in vivo flavor release and perception was evaluated for a firm and a soft custard which varied in carboxymethyl cellulose concentrations. The group of sensory assessors could be divided in two, one group rating higher odor/flavor scores for the firmer custard and

  11. Diversity and composition of vaginal microbiota of pregnant women at risk for transmitting Group B Streptococcus treated with intrapartum penicillin

    OpenAIRE

    Roesch,Luiz Fernando Wurdig; Rita C. Silveira; Corso,Andréa L.; Dobbler, Priscila Thiago; Mai, Volker; Rojas, Bruna S.; Laureano, Álvaro M.; Renato S. Procianoy

    2017-01-01

    Background Administering intravenous antibiotics during labor to women at risk for transmitting Group B Streptococcus (GBS) can prevent infections in newborns. However, the impact of intrapartum antibiotic prophylaxis on mothers’ microbial community composition is largely unknown. We compared vaginal microbial composition in pregnant women experiencing preterm birth at ≤ 32 weeks gestation that received intrapartum antibiotic prophylaxis with that in controls. Methods Microbiota in vaginal sw...

  12. Influence of water sorption on resin composite color and color variation amongst various composite brands with identical shade code: an in vitro evaluation

    NARCIS (Netherlands)

    S. Ardu; D. Gutemberg; I. Krejci; A.J. Feilzer; E. Di Bella; D. Dietschi

    2011-01-01

    Objective The aim of this study was to evaluate the influence of 1 week water storage on color stability of A2 enamel and dentine shade of 13 resin composites intended for anterior restorations and to evaluate the interchangeability of different composite brands of equal color shade. Methods 6 sampl

  13. Influence of cooling rate on interlaminar fracture properties of unidirectional commingled CF/PEEK composites

    Science.gov (United States)

    Beehag, Andrew; Ye, Lin

    1995-05-01

    The influence of cooling rates on the mechanical property profile (transverse flexure properties and modes-I and -II interlaminar fracture toughness) has been investigated for unidirectional commingled CF/PEEK composites. A laboratory hot press with a steel mould was used to process the composites at 400°C for 60 min, at an applied pressure of 1 MPa. Cooling rates from fast (quenching in oil) to slow (hot press cooling) were achieved at ambient pressure. The results indicate that different matrix morphology was found at different cooling conditions, although deconsolidation occurred in the CF/PEEK composites during cooling. When the cooling rate was shifted from slow to fast, consolidation quality of the CF/PEEK composites was improved. The resulting effect of the consolidation quality and cooling rates on the mechanical property profile of commingled CF/PEEK composites is presented. It was found that the effect of the cooling rate on the mechanical property profile of the commingled CF/PEEK composites could not be isolated from the consolidation quality.

  14. Influence of Coalescence on the Anisotropic Mechanical and Electrical Properties of Nickel Powder/Polydimethylsiloxane Composites

    Directory of Open Access Journals (Sweden)

    Sung-Hwan Jang

    2016-03-01

    Full Text Available Multifunctional polymer-based composites have been widely used in various research and industrial applications, such as flexible and stretchable electronics and sensors and sensor-integrated smart structures. This study investigates the influence of particle coalescence on the mechanical and electrical properties of spherical nickel powder (SNP/polydimethylsiloxane (PDMS composites in which SNP was aligned using an external magnetic field. With the increase of the volume fraction of the SNP, the aligned SNP/PDMS composites exhibited a higher tensile strength and a lower ultimate strain. In addition, the composites with aligned SNP showed a lower percolation threshold and a higher electrical conductivity compared with those with randomly dispersed SNP. However, when the concentration of the SNP reached a certain level (40 vol. %, the anisotropy of the effective material property became less noticeable than that of the lower concentration (20 vol. % composites due to the change of the microstructure of the particles caused by the coalescence of the particles at a high concentration. This work may provide rational methods for the fabrication of aligned composites.

  15. INFLUENCE OF REFRACTORY FILLERS ON THE PROCESS OF COMPOSITE BRAZING OF DIAMOND-ABRASIVE TOOLS

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    Kozachenko A. D.

    2015-04-01

    Full Text Available Brazes with increased viscosity are needed for brazing of abrasive diamond tools with working surface of complex contoured shape. It’s known that high viscosity is a property of composite brazes consisting of fusible matrix and refractory filler that is not melting during brazing. Goal of the work is to research the influence of refractory fillers on the process of composite brazing of diamond-abrasive tools and on that basis discover the optimal composition of braze. Composite brazes Sn-Cu-Co were researched in the work. It is determined that at least 26-28% (by mass of cobalt powder should be included in brazes for giving the braze Sn-Cu-Co necessary viscosity and for creation of uniform diamond-comprising layers with thickness up to 2.5 mm on the vertical layers and sharp edges of tools. It is determined that solid-state sintering of powders on the initial stage of heating the composite braze leads to emerging of internal stresses and forming cracks. Inert additions that prevent solid-state sintering should be include in braze to prevent cracking. Optimal inert addition for brazes Sn-Cu-Co is the tungsten powder. Minimum content of tungsten needed to prevent cracking is 6% (by mass. Optimal content of components in composition braze for brazing shaped diamond-abrasive tools is (% by mass: 30 Co, 20 Sn, 43 Cu, 7 W

  16. Richness, composition and trophic groups of an avian community in the Pernambuco Endemism Centre, Alagoas, Brazil.

    Science.gov (United States)

    Toledo-Lima, Guilherme S; Macario, Phoeve; Lyra-Neves, Rachel M de; Teixeira, Bruno P; Lima, Luiz A F de; Sugliano, Gabriel O S; Telino-Júnior, Wallace R

    2014-09-01

    In northeastern Brazil, the reduction of the natural forest cover to a series of small, isolated fragments has had negative consequences for the local avian fauna, in particular, a loss of the more specialized species, while the populations of some generalists have tended to increase. The present study focuses on the composition and trophic groups of a bird community on a farm in the northeastern Brazilian state of Alagoas. Monthly surveys were conducted between November 2008 and October 2009, based on mist-netting and systematic observations. Overall, 112 species were recorded, of which 76 were associated with the two forest fragments surveyed, while all the others were observed exclusively in the surrounding matrix of pasture and orchards. The bird community presented a predominance of insectivorous species, followed by omnivores. However, specialized trunk-creeping and understory insectivores accounted for only around 15% of the species in this feeding category. The reduced diversity of other guilds and species with more specialized diets, and the complete absence of sensitive species such as large parrots and raptors, reflects the severe fragmentation and degradation of the local forests, which has greatly reduced the availability of dietary resources and breeding sites.

  17. Richness, composition and trophic groups of an avian community in the Pernambuco Endemism Centre, Alagoas, Brazil

    Directory of Open Access Journals (Sweden)

    GUILHERME S. TOLEDO-LIMA

    2014-09-01

    Full Text Available In northeastern Brazil, the reduction of the natural forest cover to a series of small, isolated fragments has had negative consequences for the local avian fauna, in particular, a loss of the more specialized species, while the populations of some generalists have tended to increase. The present study focuses on the composition and trophic groups of a bird community on a farm in the northeastern Brazilian state of Alagoas. Monthly surveys were conducted between November 2008 and October 2009, based on mist-netting and systematic observations. Overall, 112 species were recorded, of which 76 were associated with the two forest fragments surveyed, while all the others were observed exclusively in the surrounding matrix of pasture and orchards. The bird community presented a predominance of insectivorous species, followed by omnivores. However, specialized trunk-creeping and understory insectivores accounted for only around 15% of the species in this feeding category. The reduced diversity of other guilds and species with more specialized diets, and the complete absence of sensitive species such as large parrots and raptors, reflects the severe fragmentation and degradation of the local forests, which has greatly reduced the availability of dietary resources and breeding sites.

  18. [Nutritional support groups at a hospital setting. Size, composition, relationships and actions].

    Science.gov (United States)

    Santana Porbén, S; Barreto Penié, J

    2007-01-01

    The hospital Nutricional Support Group (NSG) represents the ultimate step in the evolution of the forms of provision of nutritional and feeding care to hospitalized patients. The NSG outdoes other preceeding forms for its harmony and cohesion among its members, the multi-, inter- and transdisciplinarity, the dedication to the activity on a full time basis, and the capability to self-finance by means of the savings derived from the implementation of a nutritional policy consistent with the Good Practices of Feeding and Nutrition. It is to be expected that the inception and operation of a NSG in a hospital environment allows the realization of the benefits embedded into the Metabolic, Nutritional and Feeding Intervention Programs. Guidelines and recommendations for the definition of the size and composition of an hospital NSG are presented in this article, along with the responsabilities, functions and tasks to be assumed by its members, and a timetable for its implementation, always from the experiencies of the authors after conducting a NSG in a tertiary-care hospital in Havana (Cuba).

  19. Long-term warming alters richness and composition of taxonomic and functional groups of arctic fungi.

    Science.gov (United States)

    Geml, József; Morgado, Luis N; Semenova, Tatiana A; Welker, Jeffrey M; Walker, Marilyn D; Smets, Erik

    2015-08-01

    Fungi, including symbionts, pathogens and decomposers, play crucial roles in community dynamics and nutrient cycling in terrestrial ecosystems. Despite their ecological importance, the response of most arctic fungi to climate warming is unknown, so are their potential roles in driving the observed and predicted changes in tundra communities. We carried out deep DNA sequencing of soil samples to study the long-term effects of experimental warming on fungal communities in dry heath and moist tussock tundra in Arctic Alaska. The data presented here indicate that fungal community composition responds strongly to warming in the moist tundra, but not in the dry tundra. While total fungal richness was not significantly affected by warming, there were clear correlations among operational taxonomic unit richness of various ecological and taxonomic groups and long-term warming. Richness of ectomycorrhizal, ericoid mycorrhizal and lichenized fungi generally decreased with warming, while richness of saprotrophic, plant and animal pathogenic, and root endophytic fungi tended to increase in the warmed plots. More importantly, various taxa within these functional guilds followed opposing trends that highlight the importance of species-specific responses to warming. We recommend that species-level ecological differences be taken into account in climate change and nutrient cycling studies that involve arctic fungi. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  20. Influence of axial load on the lateral pile groups response in cohesionless and cohesive soil

    Institute of Scientific and Technical Information of China (English)

    Jasim M. ABBASA[1; Zamri CHIK[2; Mohd Raihan TAHA[2

    2015-01-01

    The lateral response of single and group of piles under simultaneous vertical and lateral loads has been analyzed using a 3D finite element approach. The response in this assessment considered lateral pile displacement and lateral soil resistance and corresponding p-y curve. As a result, modified p-y curves for lateral single pile response were improved with respect to the influence of increasing axial load intensities. The improved plots can be used for lateral loaded pile design and to produce the group action design p-multiplier curves and equations. The effect of load combination on the lateral pile group response was performed on three pile group configurations (i.e., 2 × 1, 2 × 2 and 3 × 2) with four pile spacings (i.e., s = 2D, 4D, 6D and 8D). As a result, design curves were developed and applied on the actual case studies and similar expected cases for assessment of pile group behavior using improved p-multiplier. A design equation was derived from predicted design curves to be used in the evaluation of the lateral pile group action taking into account the effect of axial load intensities. It was found that the group interaction effect led to reduced lateral resistance for the pile in the group relative to that for the single pile in case of pure lateral load. While, in case of simultaneous combined loads, large axial load intensities (i.e., more than 6H, where H is lateral load values) will have an increase inp-multiplier by approximately 100% and will consequently contribute to greater group piles capacities.

  1. Neighbouring-group composition and within-group relatedness drive extra-group paternity rate in the European badger (Meles meles).

    Science.gov (United States)

    Annavi, G; Newman, C; Dugdale, H L; Buesching, C D; Sin, Y W; Burke, T; Macdonald, D W

    2014-10-01

    Extra-group paternity (EGP) occurs commonly among group-living mammals and plays an important role in mating systems and the dynamics of sexual selection; however, socio-ecological and genetic correlates of EGP have been underexplored. We use 23 years of demographic and genetic data from a high-density European badger (Meles meles) population, to investigate the relationship between the rate of EGP in litters and mate availability, mate incompatibility and mate quality (heterozygosity). Relatedness between within-group assigned mothers and candidate fathers had a negative quadratic effect on EGP, whereas the number of neighbouring-group candidate fathers had a linear positive effect. We detected no effect of mean or maximum heterozygosity of within-group candidate fathers on EGP. Consequently, EGP was associated primarily with mate availability, subject to within-group genetic effects, potentially to mitigate mate incompatibility and inbreeding. In badgers, cryptic female choice, facilitated by superfecundation, superfoetation and delayed implantation, prevents males from monopolizing within-group females. This resonates with a meta-analysis in group-living mammals, which proposed that higher rates of EGP occur when within-group males cannot monopolize within-group females. In contrast to the positive meta-analytic association, however, we found that EGP associated negatively with the number of within-group assigned mothers and the number of within-group candidate fathers; potentially a strategy to counter within-group males committing infanticide. The relationship between the rate of EGP and socio-ecological or genetic factors can therefore be intricate, and the potential for cryptic female choice must be accounted for in comparative studies.

  2. Mothers of young children cluster into 4 groups based on psychographic food decision influencers.

    Science.gov (United States)

    Byrd-Bredbenner, Carol; Abbot, Jaclyn Maurer; Cussler, Ellen

    2008-08-01

    This study explored how mothers grouped into clusters according to multiple psychographic food decision influencers and how the clusters differed in nutrient intake and nutrient content of their household food supply. Mothers (n = 201) completed a survey assessing basic demographic characteristics, food shopping and meal preparation activities, self and spouse employment, exposure to formal food or nutrition education, education level and occupation, weight status, nutrition and food preparation knowledge and skill, family member health and nutrition status, food decision influencer constructs, and dietary intake. In addition, an in-home inventory of 100 participants' household food supplies was conducted. Four distinct clusters presented when 26 psychographic food choice influencers were evaluated. These clusters appear to be valid and robust classifications of mothers in that they discriminated well on the psychographic variables used to construct the clusters as well as numerous other variables not used in the cluster analysis. In addition, the clusters appear to transcend demographic variables that often segment audiences (eg, race, mother's age, socioeconomic status), thereby adding a new dimension to the way in which this audience can be characterized. Furthermore, psychographically defined clusters predicted dietary quality. This study demonstrates that mothers are not a homogenous group and need to have their unique characteristics taken into consideration when designing strategies to promote health. These results can help health practitioners better understand factors affecting food decisions and tailor interventions to better meet the needs of mothers.

  3. Factors influencing food choices of adolescents: findings from focus-group discussions with adolescents.

    Science.gov (United States)

    Neumark-Sztainer, D; Story, M; Perry, C; Casey, M A

    1999-08-01

    To assess adolescents' perceptions about factors influencing their food choices and eating behaviors. Data were collected in focus-group discussions. The study population included 141 adolescents in 7th and 10th grade from 2 urban schools in St Paul, Minn, who participated in 21 focus groups. Data were analyzed using qualitative research methodology, specifically, the constant comparative method. Factors perceived as influencing food choices included hunger and food cravings, appeal of food, time considerations of adolescents and parents, convenience of food, food availability, parental influence on eating behaviors (including the culture or religion of the family), benefits of foods (including health), situation-specific factors, mood, body image, habit, cost, media, and vegetarian beliefs. Major barriers to eating more fruits, vegetables, and dairy products and eating fewer high-fat foods included a lack of sense of urgency about personal health in relation to other concerns, and taste preferences for other foods. Suggestions for helping adolescents eat a more healthful diet include making healthful food taste and look better, limiting the availability of unhealthful options, making healthful food more available and convenient, teaching children good eating habits at an early age, and changing social norms to make it "cool" to eat healthfully. The findings suggest that if programs to improve adolescent nutrition are to be effective, they need to address a broad range of factors, in particular environmental factors (e.g., the increased availability and promotion of appealing, convenient foods within homes schools, and restaurants).

  4. The influence of "C-factor" and light activation technique on polymerization contraction forces of resin composite

    Directory of Open Access Journals (Sweden)

    Sérgio Kiyoshi Ishikiriama

    2012-12-01

    Full Text Available OBJECTIVES: This study evaluated the influence of the cavity configuration factor ("C-Factor" and light activation technique on polymerization contraction forces of a Bis-GMA-based composite resin (Charisma, Heraeus Kulzer. MATERIAL AND METHODS: Three different pairs of steel moving bases were connected to a universal testing machine (emic DL 500: groups A and B - 2x2 mm (CF=0.33, groups C and D - 3x2 mm (CF=0.66, groups e and F - 6x2 mm (CF=1.5. After adjustment of the height between the pair of bases so that the resin had a volume of 12 mm³ in all groups, the material was inserted and polymerized by two different methods: pulse delay (100 mW/cm² for 5 s, 40 s interval, 600 mW/cm² for 20 s and continuous pulse (600 mW/cm² for 20 s. Each configuration was light cured with both techniques. Tensions generated during polymerization were recorded by 120 s. The values were expressed in curves (Force(N x Time(s and averages compared by statistical analysis (ANOVA and Tukey's test, p<0.05. RESULTS: For the 2x2 and 3x2 bases, with a reduced C-Factor, significant differences were found between the light curing methods. For 6x2 base, with high C-Factor, the light curing method did not influence the contraction forces of the composite resin. CONCLUSIONS: Pulse delay technique can determine less stress on tooth/restoration interface of adhesive restorations only when a reduced C-Factor is present.

  5. Complex viscosity induced by protein composition variation influences the aroma release of flavored stirred yogurt.

    Science.gov (United States)

    Saint-Eve, Anne; Juteau, Alexandre; Atlan, Samuel; Martin, Nathalie; Souchon, Isabelle

    2006-05-31

    Dairy protein composition is known to influence the structure and the texture characteristics of yogurt. The objective of the present work was therefore to investigate the impact of protein composition, at a constant protein level, on the physicochemical properties of 4% fat flavored stirred yogurt and, more specifically, on the rheological properties, the microstructure, and the aroma release. The results showed that caseinate-enriched yogurt generally presented changes in their microstructure network and had a higher complex viscosity than whey protein-enriched yogurt. To a lesser extent, the release of the majority of aroma compounds was lower in caseinate-enriched yogurt. It was therefore possible to quantify physicochemical interactions between aroma compounds and proteins. The influence of gel structure on the flavor release was observed and was in agreement with sensory characteristics previously studied for these products.

  6. Chemical modifications of graphene and their influence on properties of polyurethane composites: a review

    Science.gov (United States)

    Włodarczyk, D.; Urban, M.; Strankowski, M.

    2016-10-01

    Polyurethane composites are materials of great interest nowadays due to their wide range of available forms and applications in industry. Controlling and achieving unique properties via matrix modifications and addition of various specific nanofillers seems be one of the key elements to success. The purpose of this work is to briefly present some examples of graphene nanoderivatives, their syntheses, properties and influence on polyurethane matrix after application. Structural, mechanical and electrical properties of graphene nanofillers were analyzed before and after implementation into polymer matrices. Additionally properties of obtained composites were considered in the context of shape memory. The first chapter presents methods of synthesizing carbon nanofillers and some structure investigations via x-ray Diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopy. The second part discusses influence of graphene modifications on polymer structure and changes in thermomechanical properties via stress-strain tests and Thermogravimetry (TG).

  7. Influence of Aerosol Chemical Composition on Heterogeneous Ice Formation under Mid-Upper Troposphere Conditions

    Science.gov (United States)

    Kanji, Z. A.; Niemand, M.; Saathoff, H.; Möhler, O.; Chou, C.; Abbatt, J.; Stetzer, O.

    2011-12-01

    Aerosols are involved in cooling/warming the atmosphere directly via interaction with incoming solar radiation (aerosol direct effect), or via their ability to act as cloud condensation or ice nuclei (IN) and thus play a role in cloud formation (indirect effect). In particular, the physical properties of aerosols such as size and solubility and chemical composition can influence their behavior and fate in the atmosphere. Ice nucleation taking place via IN is termed as heterogeneous ice nucleation and can take place with via deposition (ice forming on IN directly from the vapor phase), condensation/immersion (freezing via formation of the liquid phase on IN) or condensation (IN colliding with supercooled liquid drops). This presentation shows how the chemical composition and surface area of various tropospherically relevant aerosols influence conditions of temperature (T) and relative humidity (RH) required for heterogeneous ice formation conditions in the mid-upper troposphere regime (253 - 220K)? Motivation for this comes first from, the importance of being able to predict ice formation accurately so as to understand the hydrological cycle since the ice is the primary initiator of precipitation forming clouds. Second, the tropospheric budget of water vapour, an especially active greenhouse gas is strongly influenced by ice nucleation and growth. Third, ice surfaces in the atmosphere act as heterogeneous surfaces for chemical reactions of trace gases (e.g., SO2, O3, NOx and therefore being able to accurately estimate ice formation rates and quantify ice surface concentrations will allow a more accurate calculation of trace gas budgets in the troposphere. Ice nucleation measurements were conducted using a self-developed continuous flow diffusion chamber and static chamber. A number of tropospherically relevant particulates with naturally-varying and laboratory-modified surface chemistry/structure were investigated for their ice formation efficiency based on highest

  8. Influence of hydroxyl group position and temperature on thermophysical properties of tetraalkylammonium hydroxide ionic liquids with alcohols.

    Science.gov (United States)

    Attri, Pankaj; Baik, Ku Youn; Venkatesu, Pannuru; Kim, In Tae; Choi, Eun Ha

    2014-01-01

    In this work, we have explored the thermophysical properties of tetraalkylammonium hydroxide ionic liquids (ILs) such as tetrapropylammonium hydroxide (TPAH) and tetrabutylammonium hydroxide (TBAH) with isomers of butanol (1-butanol, 2-butanol and 2-methyl-2-propanol) within the temperature range 293.15-313.15 K, with interval of 5 K and over the varied concentration range of ILs. The molecular interactions between ILs and butanol isomers are essential for understanding the function of ILs in related measures and excess functions are sensitive probe for the molecular interactions. Therefore, we calculated the excess molar volume (V(E) ) and the deviation in isentropic compressibility (Δκs ) using the experimental values such as densities (ρ) and ultrasonic sound velocities (u) that are measured over the whole compositions range at five different temperatures (293.15, 298.15, 303.15, 308.15 and 313.15 K) and atmospheric pressure. These excess functions were adequately correlated by using the Redlich-Kister polynomial equation. It was observed that for all studied systems, the V(E) and Δκs values are negative for the whole composition range at 293.15 K. And, the excess function follows the sequence: 2-butanol>1-butanol>2-methyl-2-propanol, which reveals that (primary or secondary or tertiary) position of hydroxyl group influence the magnitude of interactions with ILs. The negative values of excess functions are contributions from the ion-dipole interaction, hydrogen bonding and packing efficiency between the ILs and butanol isomers. Hence, the position of hydroxyl group plays an important role in the interactions with ILs. The hydrogen bonding features between ILs and alcohols were analysed using molecular modelling program by using HyperChem 7.

  9. Influence of hydroxyl group position and temperature on thermophysical properties of tetraalkylammonium hydroxide ionic liquids with alcohols.

    Directory of Open Access Journals (Sweden)

    Pankaj Attri

    Full Text Available In this work, we have explored the thermophysical properties of tetraalkylammonium hydroxide ionic liquids (ILs such as tetrapropylammonium hydroxide (TPAH and tetrabutylammonium hydroxide (TBAH with isomers of butanol (1-butanol, 2-butanol and 2-methyl-2-propanol within the temperature range 293.15-313.15 K, with interval of 5 K and over the varied concentration range of ILs. The molecular interactions between ILs and butanol isomers are essential for understanding the function of ILs in related measures and excess functions are sensitive probe for the molecular interactions. Therefore, we calculated the excess molar volume (V(E and the deviation in isentropic compressibility (Δκs using the experimental values such as densities (ρ and ultrasonic sound velocities (u that are measured over the whole compositions range at five different temperatures (293.15, 298.15, 303.15, 308.15 and 313.15 K and atmospheric pressure. These excess functions were adequately correlated by using the Redlich-Kister polynomial equation. It was observed that for all studied systems, the V(E and Δκs values are negative for the whole composition range at 293.15 K. And, the excess function follows the sequence: 2-butanol>1-butanol>2-methyl-2-propanol, which reveals that (primary or secondary or tertiary position of hydroxyl group influence the magnitude of interactions with ILs. The negative values of excess functions are contributions from the ion-dipole interaction, hydrogen bonding and packing efficiency between the ILs and butanol isomers. Hence, the position of hydroxyl group plays an important role in the interactions with ILs. The hydrogen bonding features between ILs and alcohols were analysed using molecular modelling program by using HyperChem 7.

  10. The potential influence of short-term environmental variability on the composition of testate amoeba communities in Sphagnum peatlands.

    Science.gov (United States)

    Sullivan, Maura E; Booth, Robert K

    2011-07-01

    Testate amoebae are a group of moisture-sensitive, shell-producing protozoa that have been widely used as indicators of changes in mean water-table depth within oligotrophic peatlands. However, short-term environmental variability (i.e., sub-annual) also probably influences community composition. The objective of this study was to assess the potential influence of short-term environmental variability on the composition of testate amoeba communities in Sphagnum-dominated peatlands. Testate amoebae and environmental conditions, including hourly measurements of relative humidity within the upper centimeter of the peatland surface, were examined throughout the 2008 growing season at 72 microsites within 11 peatlands of Pennsylvania and Wisconsin, USA. Relationships among testate amoeba communities, vegetation, depth to water table, pH, and an index of short-term environmental variability (EVI), were examined using nonmetric multidimensional scaling and correlation analysis. Results suggest that EVI influences testate amoeba communities, with some taxa more abundant under highly variable conditions (e.g., Arcella discoides, Difflugia pulex, and Hyalosphenia subflava) and others more abundant when environmental conditions at the peatland surface were relatively stable (e.g., Archerella flavum and Bullinularia indica). The magnitude of environmental variability experienced at the peatland surface appears to be primarily controlled by vegetation composition and density. In particular, sites with dense Sphagnum cover had lower EVI values than sites with loose-growing Sphagnum or vegetation dominated by vascular plants and/or non-Sphagnum bryophytes. Our results suggest that more environmental information may be inferred from testate amoebae than previously recognized. Knowledge of relationships between testate amoebae and short-term environmental variability should lead to more detailed and refined environmental inferences.

  11. Dielectric property of polyimide/barium titanate composites and its influence factors (Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    Weidong LIU; Baoku ZHU; Shuhui XIE; Zhikang XU

    2008-01-01

    Using poly(amic acid) (PAA) as a precursor followed by thermal imidization, the polyimide/barium titanate composite films were successfully prepared by a direct mixing method and in situ process. The influence of processing factors, such as particle size, distribution mode and polymerization method on dielectric prop-erties was studied. Results revealed that the dielectric constant (ε) of the composite film increased by using bigger fillers or employing in situ polymerization and bimodal distribution. When the composite film contain-ing 50 Vol-% of BaTiO3 with size in 100 nm was pre-pared via in situ process, its dielectric constant reached 45 at 10 kHz.

  12. Influence of seasonality on the chemical composition of oysters (Crassostrea rhizophorae).

    Science.gov (United States)

    Lira, Giselda M; Pascoal, Jadna C M; Torres, Elizabeth A F S; Soares, Rosana A M; Mendonça, Simone; Sampaio, Geni R; Correia, Meiryellen S; Cabral, Caterine C V Q; Cabral Júnior, Cyro R; López, Ana M Q

    2013-06-01

    This paper aimed to evaluate the influence of seasonality on the chemical composition of oysters (Crassostrea rhizophorae). Samples were collected during summer and winter from the estuary and lagoon complex of the municipality of Barra de São Miguel, Alagoas, Brazil. Statistical differences (p<0.05) between summer and winter were observed in relation to chemical composition. The oysters cultivated in the winter presented some nutritional advantages because of the higher levels of proteins and functional nutrients, such as the eicosapentaenoic-docosahexaenoic acid combination and percentages of polyunsaturated fatty acids (n-3 and n-6), and the lower levels of saturated fatty acids. Therefore, the animals in winter presented a higher content of cholesterol oxides. The levels of cholesterol oxides found in these products during winter may encourage researchers to investigate the composition of oysters cultivated in different climates all over the world. Copyright © 2012. Published by Elsevier Ltd.

  13. Influence of Carbon Nanotubes on Thermal Stability of Water-Dispersible Nanofibrillar Polyaniline/Nanotube Composite

    Directory of Open Access Journals (Sweden)

    Zhi-Bin Zhang

    2012-02-01

    Full Text Available Significant influence on the thermal stability of polyaniline (PANI in the presence of multi-walled carbon nanotubes (MWCNTs is reported. By means of in-situ rapid mixing approach, water-dispersible nanofibrillar PANI and composites, consisting of MWCNTs uniformly coated with PANI in the state of emeraldine salt, with a well-defined core-shell heterogeneous structure, were prepared. The de-protonation process in PANI occurs at a lower temperature under the presence of MWCNTs on the polyaniline composite upon thermal treatment. However, it is found that the presence of MWCNTs significantly enhances the thermal stability of PANI’s backbone upon exposure to laser irradiation, which can be ascribed to the core-shell heterogeneous structure of the composite of MWCNTs and PANI, and the high thermal conductivity of MWCNTs.

  14. Influence of γ-ray Irradiation on the PTC Effect of EPDM/Carbon Black Composite

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@ Introduction The positive temperature coefficient(PTC) effect is characterized by an increase of resistivity with an elevated temperature.The PTC effect of carbon black(CB) filled polymers is useful for self-regulation heaters,over-current protectors,sensors,etc.Much work has been done on the PTC effect of the carbon black filled crystalline polymer composite[1-4],whereas carbon black filled amorphous polymers have not drawn researchers much attention because the PTC effect in these composites is small or cannot be detected[5-7].In this work,the influence of γ-ray irradiation on the PTC effect of CB filled amorphous ethylene-propylene-diene terpolymer(EPDM) composites was studied.

  15. Influence of the polymeric coating thickness on the electrochemical performance of Carbon Fiber/PAni composites

    Directory of Open Access Journals (Sweden)

    Carla Polo Fonseca

    2015-10-01

    Full Text Available Abstract Carbon fiber/polyaniline composites (CF/PAni were synthesized at three different deposition time of 30, 60 and 90 min by oxidative polymerization. The composite materials were morphologically and physically characterized by scanning electron microscopy and by Raman spectroscopy, respectively. Their electrochemical responses were analyzed by cyclic voltammetry, by galvanostatic test, and by electrochemical impedance spectroscopy. The influence of the PAni layer thickness deposited on carbon fibers for the composite formation as well as for their electrochemical properties was discussed. The CF/PAni-30 showed a nanometric thickness with more homogeneous morphology compared to those formed in deposition times of 60 and 90 min. It also showed, from the electrochemical impedance spectroscopy measurements, the lowest charge transfer resistance value associated to the its highest value for the double-layer capacitance of 180 Fg-1 making it a very strong candidate as a supercapacitor electrode.

  16. Assessment of factors influencing surface roughness on the machining of Al/SiC particulate composites

    Energy Technology Data Exchange (ETDEWEB)

    Palanikumar, K. [Department of Mechanical and Production Engineering, Sathyabama Institute of Science and Technology, Deemed University, Chennai 600 119, Tamilnadu (India)]. E-mail: palanikumar_k@yahoo.com; Karthikeyan, R. [Department of Manufacturing Engineering, Annamalai University, Chidambaram 608001 (India)

    2007-07-01

    The utilization of Al/SiC particulate composite materials in many different engineering fields has undergone a tremendous increase. Accordingly, the need for accurate machining of composites has increased enormously. In the present study, an attempt has been made to assess the factors influencing surface roughness on the machining of Al/SiC particulate composites. Experimental design concept has been used for experimentation. The machining experiments were conducted on lathe using tungsten carbide tool inserts (K10) with two levels of factors. The factors considered were: % volume fraction of SiC, cutting speed, depth of cut and feed rate. A procedure has been developed to assess and optimize the chosen factors to attain minimum surface roughness by incorporating: (i) response table and response graph, (ii) normal probability plot (iii) interaction graphs and (iv) analysis of variance (ANOVA) technique.

  17. Influence of metal loading on hydrocracking of rapeseed oil using bifunctional micro-/mesoporous composite materials

    Energy Technology Data Exchange (ETDEWEB)

    Gille, T.; Busse, O.; Reschetilowski, W. [Technische Univ. Dresden (Germany). Inst. of Industrial Chemistry

    2013-11-01

    Hydrocracking of rapeseed oil has been investigated in a fixed bed reactor under integral conditions. A synthesized micro-/mesoporous composite material Al-MCM-41/ZSM-5 modified by different metal loadings (NiMo, PtNiMo, Pt) was used as catalyst system. It could be demonstrated that the support material and their metal loading influence the product selectivity as well as the deactivation tendencies of the catalyst sample. (orig.)

  18. The influence of nano-ceramic modifier on the structure and properties of polyolefin composites

    Science.gov (United States)

    Sudnik, L.; Dubkova, V.; Galinovsky, A.; Osipkov, A.

    2016-10-01

    It has been shown, that the nano-ceramic modifier boehmite, with specific surface area of up to 400 m2/g and dispersion degree of less than100 nm, is a structurally active filler of an ultra-high-molecular-weight polyethylene. The boehmite influences the polymer crystalline and supra-molecular structure, during crystallization of the polymer from the melt under uniaxial plastic deformation conditions. It results in the production of nano-composites with an improved complex of properties.

  19. The Influence of Group Versus Individual Prenatal Care on Phase of Labor at Hospital Admission.

    Science.gov (United States)

    Tilden, Ellen L; Emeis, Cathy L; Caughey, Aaron B; Weinstein, Sarah R; Futernick, Sarah B; Lee, Christopher S

    2016-07-01

    Group prenatal care, an alternate model of prenatal care delivery, has been associated with various improved perinatal outcomes in comparison to standard, individual prenatal care. One important maternity care process measure that has not been explored among women who receive group prenatal care versus standard prenatal care is the phase of labor (latent vs active) at hospital admission. A retrospective case-control study was conducted comparing 150 women who selected group prenatal care with certified nurse-midwives (CNMs) versus 225 women who chose standard prenatal care with CNMs. Analyses performed included descriptive statistics to compare groups and multivariate regression to evaluate the contribution of key covariates potentially influencing outcomes. Propensity scores were calculated and included in regression models. Women within this sample who received group prenatal care were more likely to be in active labor (≥ 4 cm of cervical dilatation) at hospital admission (odds ratio [OR], 1.73; 95% confidence interval [CI], 1.03-2.99; P = .049) and were admitted to the hospital with significantly greater cervical dilatation (mean [standard deviation, SD] 5.7 [2.5] cm vs. 5.1 [2.3] cm, P = .005) compared with women who received standard prenatal care, controlling for potential confounding variables and propensity for group versus individual care selection. Group prenatal care may be an effective and safe intervention for decreasing latent labor hospital admission among low-risk women. Neither group prenatal care nor active labor hospital admission was associated with increased morbidity. © 2016 by the American College of Nurse-Midwives.

  20. Influence of Reprocessing in the formation of functional groups during low density polyethylene aging

    Directory of Open Access Journals (Sweden)

    Maurício M. Selonke

    2012-01-01

    Full Text Available In recent years, the interest in polymer recycling has increased. However, in every reprocessing step the material undergoes shear stress and is affected by temperature and oxygen. The aim of this paper is to investigate the influence of multiple extrusion in the generation of functional groups, namely hydroperoxide, carbonyl, and transvinylene. Low density polyethylene was reprocessed three times in a single screw extruder. In each recycling step hot pressed films were prepared. These films were submitted to a heat treatment in an oven with air circulation and renovation to proceed with aging tests at different times and temperatures. The results obtained showed that all functional groups had their concentration increased with the increase in number of reprocessing, the aging time and temperature of the heat treatment. The factorial design was applied to verify the influence of these parameters. All the parameters had significant effects, since their regression coefficients had the same order of magnitude, with the most influential parameter being the aging temperature, followed by the aging time and number of extrusions. Most of the interactions were influential, indicating that the formation of functional groups depends upon their interaction, and not only on their isolated effects.

  1. Neighbouring-group composition and within-group relatedness drive extra-group paternity rate in the European badger (Meles meles)

    NARCIS (Netherlands)

    Annavi, G.; Newman, C.; Dugdale, H. L.; Buesching, C. D.; Sin, Y. W.; Burke, T.; Macdonald, D. W.

    2014-01-01

    Extra-group paternity (EGP) occurs commonly among group-living mammals and plays an important role in mating systems and the dynamics of sexual selection; however, socio-ecological and genetic correlates of EGP have been underexplored. We use 23years of demographic and genetic data from a high-densi

  2. Contralateral delay activity tracks the influence of Gestalt grouping principles on active visual working memory representations.

    Science.gov (United States)

    Peterson, Dwight J; Gözenman, Filiz; Arciniega, Hector; Berryhill, Marian E

    2015-10-01

    Recent studies have demonstrated that factors influencing perception, such as Gestalt grouping cues, can influence the storage of information in visual working memory (VWM). In some cases, stationary cues, such as stimulus similarity, lead to superior VWM performance. However, the neural correlates underlying these benefits to VWM performance remain unclear. One neural index, the contralateral delay activity (CDA), is an event-related potential that shows increased amplitude according to the number of items held in VWM and asymptotes at an individual's VWM capacity limit. Here, we applied the CDA to determine whether previously reported behavioral benefits supplied by similarity, proximity, and uniform connectedness were reflected as a neural savings such that the CDA amplitude was reduced when these cues were present. We implemented VWM change-detection tasks with arrays including similarity and proximity (Experiment 1); uniform connectedness (Experiments 2a and 2b); and similarity/proximity and uniform connectedness (Experiment 3). The results indicated that when there was a behavioral benefit to VWM, this was echoed by a reduction in CDA amplitude, which suggests more efficient processing. However, not all perceptual grouping cues provided a VWM benefit in the same measure (e.g., accuracy) or of the same magnitude. We also found unexpected interactions between cues. We observed a mixed bag of effects, suggesting that these powerful perceptual grouping benefits are not as predictable in VWM. The current findings indicate that when grouping cues produce behavioral benefits, there is a parallel reduction in the neural resources required to maintain grouped items within VWM.

  3. The influence of irradiated wood filler on some properties of polypropylene - wood composites

    Directory of Open Access Journals (Sweden)

    Điporović-Momčilović Milanka

    2007-01-01

    Full Text Available The problem of compatibility between the wood filler and thermoplastic matrix is of essential importance in composite production. Numerous methods have been developed for increasing this compatibility, which is still representing a challenging objective of composite research throughout the world. The research into these methods is primarily directed towards their efficiency from the viewpoint of the composite performance and their economical acceptability. The latter is of particular importance for the composite production in the developing countries with respect to the shortage of the corresponding funds. With this respect, the utilization of ionizing radiation might have considerable advantages. In this research, the beech wood flour was irradiated by a dose of 10 kGy of 60Co gamma rays for purpose of provoking the changes by the ionizing effect. The effects of ionizing radiation upon the properties of wood particles have been examined by IR spectroscopy and by determination of contents of hydroxyl groups in wood by acetylating as an indirect method. All these methods have been expected to reveal the chemical effects of the applied radiation treatment. The irradiated and the control wood flour were used in order to produce the samples of composite with polypropylene. The polypropylene-wood flour (PP-WF composites were produced with 40% of wood particles having fraction size 0.3 mm. The melt-blended composites were modified with amido-acrylic acid (AMACA as a new coupling agent synthesized for this propose in amount of 6 wt.% (based on wood filler and successively with 0.05 wt.% (based on PP of organic peroxide during mixing step. The composites containing coupling agents showed superior mechanical properties, compared to the untreated one. The highest extent of improvement of tensile was achieved in PP-WFl composites modified with AMACA coupling agent.

  4. Habitat architecture influencing microcrustaceans composition: a case study on freshwater Cladocera (Crustacea Branchiopoda).

    Science.gov (United States)

    Debastiani-Júnior, J R; Elmoor-Loureiro, L M A; Nogueira, M G

    2016-02-01

    Environmental complexity is considered a key factor for diversity enhancement in aquatic ecosystems. Macrophyte stands are a major contributor for this complexity due to their differential architectures. Nevertheless, the influence of distinct aquatic habitat architectures (with different types of macrophytes or without them) on microcrustaceans' taxa composition, usually found in macrophyte colonized water bodies, is underexplored in limnological studies. The main objective of this study was to analyze this influence by comparing the Cladocera composition among four habitat architectures: (1) fluctuant macrophytes, (2) rooted emergent macrophytes, (3) submerged macrophytes and (4) the limnetic zone of oxbow lakes associated to a large subtropical reservoir. Wide compositional variation was observed. Fluctuant macrophytes exhibited the richest Cladocera assemblage, dominated by Chydoridae. Submerged and rooted emergent macrophytes had the most similar assemblages between them. The most distinctive fauna was found in the limnetic zone, dominated by Bosminidae. Probable differences in resource availability in each sampled habitat architecture are considered as the driving factor for the Cladocera composition variation. We concluded that for a complete inventory of a given local fauna, it is imperative to take into account the aquatic habitat architecture, including macrophyte stands, in the data sampling design.

  5. Habitat architecture influencing microcrustaceans composition: a case study on freshwater Cladocera (Crustacea Branchiopoda

    Directory of Open Access Journals (Sweden)

    J. R. Debastiani-Júnior

    Full Text Available Abstract Environmental complexity is considered a key factor for diversity enhancement in aquatic ecosystems. Macrophyte stands are a major contributor for this complexity due to their differential architectures. Nevertheless, the influence of distinct aquatic habitat architectures (with different types of macrophytes or without them on microcrustaceans’ taxa composition, usually found in macrophyte colonized water bodies, is underexplored in limnological studies. The main objective of this study was to analyze this influence by comparing the Cladocera composition among four habitat architectures: (1 fluctuant macrophytes, (2 rooted emergent macrophytes, (3 submerged macrophytes and (4 the limnetic zone of oxbow lakes associated to a large subtropical reservoir. Wide compositional variation was observed. Fluctuant macrophytes exhibited the richest Cladocera assemblage, dominated by Chydoridae. Submerged and rooted emergent macrophytes had the most similar assemblages between them. The most distinctive fauna was found in the limnetic zone, dominated by Bosminidae. Probable differences in resource availability in each sampled habitat architecture are considered as the driving factor for the Cladocera composition variation. We concluded that for a complete inventory of a given local fauna, it is imperative to take into account the aquatic habitat architecture, including macrophyte stands, in the data sampling design.

  6. Determination of the chemical composition of human renal stones with MDCT: influence of the surrounding media

    Science.gov (United States)

    Grosjean, Romain; Sauer, Benoît; Guerra, Rui; Kermarrec, Isabelle; Ponvianne, Yannick; Winninger, Daniel; Daudon, Michel; Blum, Alain; Felblinger, Jacques; Hubert, Jacques

    2007-03-01

    The selection of the optimal treatment method for urinary stones diseases depends on the chemical composition of the stone and its corresponding fragility. MDCT has become the most used modality to determine rapidly and accurately the presence of stones when evaluating urinary lithiasis treatment. That is why several studies have tempted to determine the chemical composition of the stones based on the stone X-ray attenuation in-vitro and invivo. However, in-vitro studies did not reproduce the normal abdominal wall and fat, making uncertain the standardization of the obtained values. The aim of this study is to obtain X-ray attenuation values (in Hounsfield Units) of the six more frequent types of human renal stones (n=217) and to analyze the influence of the surrounding media on these values. The stones were first placed in a jelly, which X-ray attenuation is similar to that of the human kidney (30 HU at 120 kV). They were then stuck on a grid, scanned in a water tank and finally scanned in the air. Significant differences in CT-attenuation values were obtained with the three different surrounding media (jelly, water, air). Furthermore there was an influence of the surrounding media and consequently discrepancies in determination of the chemical composition of the renal stones. Consequently, CT-attenuation values found in in-vitro studies cannot really be considered as a reference for the determination of the chemical composition except if the used phantom is an anthropomorphic one.

  7. Influence of Synthetic Fibers Angle Orientation on Bending Properties of Composite Plywood

    Directory of Open Access Journals (Sweden)

    Mladen Brezović

    2010-12-01

    Full Text Available This paper presents the results of research on carbon fiber angle orientation and quantity of carbon fi bers in yarn on bending properties of plywood. For that purpose the specimens have been defined as multilayer composites made from carbon fibers and veneer. Carbon fibers were inserted in the second and third glue line of the composite with angle variation of 15°. Stresses and strain were analyzed in significant layers together with displacement of the whole composite plate. The influence of carbon fiber angle orientation on properties of the composite (amount of stresses and related strains was significant. The best results have been achieved with carbon fiber angle of 0°, and bidirectional carbon fiber type (BCF with the orientation angle of 90°. The lowest values have been achieved with carbon fiber angle of 65° (unidirectional carbon fibers-UCF, and bidirectional carbon fiber type (BCF with the orientation angle of 45°. Greater quantity of carbon fibers per one yarn has positive influence on decrease of stresses and strains in veneer layers and provides better stiffness of plywood.

  8. The influence of oxygen-containing functional groups on the dispersion of single-walled carbon nanotubes in amide solvents

    Science.gov (United States)

    Brandão, S. D. F.; Andrada, D.; Mesquita, A. F.; Santos, A. P.; Gorgulho, H. F.; Paniago, R.; Pimenta, M. A.; Fantini, C.; Furtado, C. A.

    2010-08-01

    Surface composition plays an important role in carbon nanotube dispersibility in different environments. Indeed, it determines the choice of dispersion medium. In this paper the effect of oxidation on the dispersion of HiPCO single-walled carbon nanotubes (SWNTs) in N-methyl-pyrrolidinone (NMP), N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMA), N-dodecyl-pyrrolidinone (N12P) and cyclohexyl-pyrrolidinone (CHP) was systematically studied. During the oxidation process, similar amounts of carboxylic acid and phenolic groups were introduced to mostly already existing defects. For each solvent the dispersion limits and the absorption coefficients were estimated by optical absorption analysis over a range of SWNT concentrations. The presence of acid oxygenated groups increased SWNT dispersibility in NMP, DMF and DMA, but decreased in N12P and CHP. The absorption coefficients, however, decreased for all solvents after oxidation, reflecting the weakening of the effective transition dipole of the π-π transition with even limited extension functionalization and solvent interaction. The analysis of the results in terms of Hansen and Flory-Huggins solubility parameters evidenced the influence of dipolar interactions and hydrogen bonding on the dispersibility of oxidized SWNTs.

  9. Influences of interphase on dynamic effective properties of composites reinforced by dispersed spherical particles

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The influences of interphase on dynamic effective properties of composites reinforced by randomly dispersed spherical particles were studied. A thin homogeneous elastic interphase with different shear and bulk moduli, located between the reinforced particle and the host matrix, was introduced to model the interfacial bonding state. The effects of such an interphase on the coherent plane waves were studied numerically. Numerical simulations were carried out for SiC-Al composites with four typical cases of interphase. It was found that the property of interphase has significant influences on the effective propagation constants of coherent waves and the dynamic effective elastic moduli of the composites. The influences on the coherent longitudinal wave and the coherent shear waves were different and dependent upon the frequency range. Moreover, several imperfect interface models, i.e., the spring model, mass model, and spring-mass model, were studied numerically and compared with the interphase model. It was found that the spring model is a more suitable model than the mass model for the light and weak interphase whereas the mass model is a more suitable model than the spring model for the heavy and strong interphase.

  10. Young Children’s Motor Interference is Influenced by Novel Group Membership

    Directory of Open Access Journals (Sweden)

    Johanna Elizabeth van Schaik

    2016-03-01

    Full Text Available From early childhood onwards, individuals use behavior copying to communicate liking and belonging. This nonverbal signal of affiliation is especially relevant in the context of social groups and indeed both children and adults copy in-group more than out-group members. Given the societal importance of inter-group interactions, it is imperative to understand the mechanistic level at which group modulations of copying occur early in development. The current study was designed to investigate the effect of novel group membership on young children’s motor behavior during a simultaneous movement-observation and -execution task. Four- to six-year-olds (n = 65 first gained membership to one of two novel groups based on their color preference and put on a vest in their chosen color. Subsequently, they were instructed to draw a straight line back-and-forth on a tablet computer that was concurrently displaying a stimulus video in which a model moved her arm congruently or incongruently to the child’s instructed direction. In half of the stimulus videos the model belonged to the in-group, while in the other half the model belonged to the out-group, as identified by the color of her dress. The deviations into the uninstructed direction of the children’s drawings were quantified as a measure of how much observing the models’ behaviors interfered with executing their own behaviors. The motor interference effect, namely higher deviations in the incongruent trials than in the congruent trials, was found only for the out-group condition. An additional manipulation of whether the models’ arms followed a biological or non-biological velocity profile had little effect on children’s motor interference. The results are interpreted in the context of the explicit coordinative nature of the task as an effect of heightened attention towards interacting with an out-group member. This study demonstrates that already during early childhood, novel group

  11. Factors influencing GPs’ choice between drugs in a therapeutic drug group. A qualitative study

    DEFF Research Database (Denmark)

    Buusman, Allan; Andersen, Morten; Merrild, Camilla Hoffmann

    2007-01-01

    Objective. To explore how GPs choose between drugs in a therapeutic drug group. Design. A qualitative study based on semi-structured ethnographic interviews. Setting and subjects. General practitioners from the counties of both Funen and West Zealand in Denmark. A total of 15 general practitioners...... as it was a recurring theme during all interviews. External factors outside the GP's control such as governmental regulation on prescribing and the pharmaceutical industry influenced most GPs. Internal factors related to the actual consultation included characteristics of the GP and the patient, drug characteristics...

  12. Personality-dependent dispersal in the invasive mosquitofish: group composition matters.

    Science.gov (United States)

    Cote, Julien; Fogarty, Sean; Brodin, Tomas; Weinersmith, Kelly; Sih, Andrew

    2011-06-07

    Understanding/predicting ecological invasions is an important challenge in modern ecology because of their immense economical and ecological costs. Recent studies have revealed that within-species variation in behaviour (i.e. animal personality) can shed light on the invasion process. The general hypothesis is that individuals' personality type may affect their colonization success, suggesting that some individuals might be better invaders than others. We have recently shown that, in the invasive mosquitofish (Gambusia affinis), social personality trait was an important indicator of dispersal distance, with more asocial individuals dispersing further. Here, we tested how mean personality within a population, in addition to individual personality type, affect dispersal and settlement decisions in the mosquitofish. We found that individual dispersal tendencies were influenced by the population's mean boldness and sociability score. For example, individuals from populations with more asocial individuals or with more bold individuals are more likely to disperse regardless of their own personality type. We suggest that identifying behavioural traits facilitating invasions, even at the group level, can thus have direct applications in pest management.

  13. Chemical composition distribution analysis of photoresist copolymers and influence on ArF lithographic performance

    Science.gov (United States)

    Momose, Hikaru; Yasuda, Atsushi; Ueda, Akifumi; Iseki, Takayuki; Ute, Koichi; Nishimura, Takashi; Nakagawa, Ryo; Kitayama, Tatsuki

    2007-03-01

    For getting information about the distribution of chemical composition, several model polymers were prepared under different polymerization conditions and were measured by critical adsorption point-liquid chromatography (CAP-LC). In the copolymer system of 8- and 9- (4-oxatricyclo[5.2.1.0 2,6]decane-3-one) acrylate (OTDA) and 2-ethyl-2-adamantyl methacrylate (EAdMA), the peak shapes of the CAP-LC chromatogram varied according to the polymerization condition although they indicated same molecular weight and averaged chemical composition. The difference of the CAP-LC elution curves was related to the chemical composition distribution of copolymers for CAP-LC measurement combined with proton nuclear magnetic resonance (1H-NMR). The terpolymers consisted of α-hydroxy-γ-butyrolactone methacrylate (GBLMA), 2-methyl-2-adamantyl methacrylate (MAdMA) and 1-hydroxy-3-adamantyl methacrylate (HAdMA) were prepared under various polymerization conditions. In the terpolymer system that had same molecular weight and average chemical composition, the solubility parameter (δ) and the dissolution rate were measured. The δ value and the dissolution rate curve were different among these terpolymers. It was suggested that the δ value and the chemical composition distribution of these terpolymers have a significant influence on the lithographic performance.

  14. Considerations regarding the volume fraction influence on the wear behavior of the fiber reinforced composite systems

    Science.gov (United States)

    Caliman, R.

    2017-08-01

    This paper contains an analysis of the factors that have an influence on the tribological characteristics of the composite material sintered with metal matrix reinforced with carbon fibers. These composites are used generally if it’s needed the wear resistant materials, whereas these composites have high specific strength in conjunction with a good corrosion resistance at low densities and some self-lubricating properties. Through the knowledge of the better tribological properties of the materials and their behavior to wear, can be generated by dry and the wet friction. Thus, where necessary the use of high temperature resistant material with low friction between the elements, carbon fiber composite materials are very suitable because they have: mechanical strength and good ductility, melting temperature on the higher values, higher electrical and thermal conductivity, lower wear speed and lower friction forces. For this purpose, this paper also contains an experimental program based on the evidence of formaldehyde resin made from fiber reinforced Cu-carbon with the aim to specifically determine the volume of fibers fraction for the consolidation of the composite material. In order to determine the friction coefficient and the wear rates of the various fiber reinforced polymer mixtures of carbon have been used special devices with needle-type with steel disc. These tests were conducted in the atmosphere at the room temperature without external lubrication study taking into consideration the sliding different speeds with constant loading task.

  15. Influence of Constituents on Creep Properties of SiC/SiC Composites

    Science.gov (United States)

    Bhatt, R.; DiCarlo, J.

    2016-01-01

    SiC-SiC composites are being considered as potential candidate materials for next generation turbine components such as combustor liners, nozzle vanes and blades because of their low density, high temperature capability, and tailorable mechanical properties. These composites are essentially fabricated by infiltrating matrix into a stacked array of fibers or fiber preform by one or a combination of manufacturing methods such as, Melt Infiltration (MI) of molten silicon metal, Chemical Vapor Infiltration (CVI), Polymer Infiltration and Pyrolysis (PIP). To understand the influence of constituents, the SiC-SiC composites fabricated by MI, CVI, and PIP methods were creep tested in air between 12000 and 14500 degrees Centigrade for up to 500 hours. The failed specimens were analyzed under a scanning electron microscope to assess damage mechanisms. Also, knowing the creep deformation parameters of the fiber and the matrix under the testing conditions, the creep behavior of the composites was modeled and compared with the measured data. The implications of the results on the long term durability of these composites will be discussed.

  16. Influence of head group methylation on the phase behavior of lipid monolayers

    DEFF Research Database (Denmark)

    Brezesinski, G.; Bringezu, F.; Weidemann, G.

    1998-01-01

    per three tails exceeds that per head, an influence of the head group methylation on the monolayer structure is observed. The tilt angles at lower lateral pressures and the transition pressure to a hexagonal packing of upright oriented chains increase with increasing methylation degree. The transition...... from the NN tilted rectangular to this hexagonal phase is connected with a pressure region where the in-plane components Q(xy) of the two peaks coincide while the out-of-plane components Q(z) differ. This indicates an undistorted hexagonal in-plane lattice even for tilted chains. The area-pressure...... and X-ray measurements below 10 mN/m, can be explained by the formation of holes in the monolayer. Possibly the tilting of the triple-chain molecules leads to an orientational ordering of the head group dipoles and therefore to an electrostatic repulsion between condensed phase domains. (C) 1998...

  17. Influence of a Neighboring Charged Group on Hydrophobic Hydration Shell Structure.

    Science.gov (United States)

    Davis, Joel G; Zukowski, Samual R; Rankin, Blake M; Ben-Amotz, Dor

    2015-07-23

    Raman multivariate curve resolution (Raman-MCR), as well as quantum and classical calculations, are used to probe water structural changes in the hydration shells of carboxylic acids and tetraalkyl ammonium ions with various aliphatic chain lengths. The results reveal that water molecules in the hydration shell around the hydrophobic chains undergo a temperature and chain length dependent structural transformation resembling that previously observed in aqueous solutions of n-alcohols. Deprotonation of the carboxylic acid headgroup (at pH ∼ 7) is found to suppress the onset of the hydration-shell structural transformation around the nearest aliphatic methylene group. Tetraalkyl ammonium cations are found to more strongly suppress the water structural transformation, perhaps reflecting the greater intramolecular charge delocalization and suppression of dangling OH defects in water's tetrahedral H-bond network. The observed coupling between ionic and hydrophobic groups, as well as the associated charge asymmetry, may influence the hydrophobicity of proteins and other materials.

  18. Surface modification influencing adsorption of red wine constituents: The role of functional groups

    Energy Technology Data Exchange (ETDEWEB)

    Mierczynska-Vasilev, Agnieszka, E-mail: agnieszka.mierczynska-vasilev@awri.com.au; Smith, Paul A., E-mail: paul.smith@awri.com.au

    2016-11-15

    Highlights: • Chemical surface composition affects behaviour of wine adsorption. • SO{sub 3}H and COOH groups adsorb more of the wine nitrogen-containing compounds. • NH{sub 2} and NR{sub 3} groups encourage carbon-containing compounds adsorption. • Red wine constituents after filtration adsorbed more on NR{sub 3} and CHO surfaces. - Abstract: The adsorption of wine constituents at solid surfaces is important in applications such as filtration and membrane fouling, binding to tanks and fittings and interactions with processing aids such as bentonite. The interaction of wine constituents with surfaces is mediated through adsorbed wine components, where the type of constituents, amount, orientation, and conformation are of consequence for the surface response. This study examines the effect of surface chemical functionalities on the adsorption of red wine constituents. Plasma-polymerized films rich in amine, carboxyl, hydroxyl, formyl and methyl functional groups were generated on solid substrates whereas, glycidyltrimethylammonium chloride was covalently attached to allylamine plasma-polymer modified surface and poly(sodium styrenesulfonate) was electrostatically adsorbed to an amine plasma-polymerized surface. The surface chemical functionalities were characterized by X-ray photoelectron spectroscopy. The ability of different substrates to adsorb red wine constituents was evaluated by quartz crystal microbalance and atomic force microscopy. The results showed that substrates modified with −SO{sub 3}H and –COOH groups can adsorb more of the wine nitrogen-containing compounds whereas −NH{sub 2} and −NR{sub 3} groups encourage carbon-containing compounds adsorption. Red wine constituents after filtration were adsorbed in higher extend on −NR{sub 3} and –CHO surfaces. The –OH modified surfaces had the lowest ability to absorb wine components.

  19. Heat treatment of a direct composite resin: influence on flexural strength

    Directory of Open Access Journals (Sweden)

    Caroline Lumi Miyazaki

    2009-09-01

    Full Text Available The purpose of this study was to evaluate the flexural strength of a direct composite, for indirect application, that received heat treatment, with or without investment. One indirect composite was used for comparison. For determination of the heat treatment temperature, thermogravimetric analysis (TGA and differential scanning calorimetry (DSC were performed, considering the initial weight loss temperature and glass transition temperature (Tg. Then, after photoactivation (600 mW/cm² - 40 s, the specimens (10 x 2 x 2 mm were heat-treated following these conditions: 170ºC for 5, 10 or 15 min, embedded or not embedded in investment. Flexural strength was assessed as a means to evaluate the influence of different heat treatment periods and investment embedding on mechanical properties. The data were analyzed by ANOVA and Tukey's test (α = 0.05. TGA showed an initial weight loss temperature of 180ºC and DSC showed a Tg value of 157°C. Heat treatment was conducted in an oven (Flli Manfredi, Italy, after 37°C storage for 48 h. Flexural strength was evaluated after 120 h at 37°C storage. The results showed that different periods and investment embedding presented similar statistical values. Nevertheless, the direct composite resin with treatments presented higher values (178.7 MPa compared to the indirect composite resin (146.0 MPa and the same direct composite submitted to photoactivation only (151.7 MPa. Within the limitations of this study, it could be concluded that the heat treatment increased the flexural strength of the direct composite studied, leading to higher mechanical strength compared to the indirect composite.

  20. Influence of microleakage, surface roughness and biofilm control on secondary caries formation around composite resin restorations: an in situ evaluation

    Directory of Open Access Journals (Sweden)

    Fábio Garcia Lima

    2009-02-01

    Full Text Available This study was carried out to evaluate in situ the influence of microleakage, surface roughness and biofilm control on caries formation around composite resin restorations. During 28 days, 12 volunteers wore palatal devices containing bovine enamel slabs restored with composite resin. Restorations were made without leakage, when the adhesive system was applied, or with leakage, when adhesive system was omitted. Half of the restorations in each group were finished and the remaining were finished and polished. In one side of the palatal device, biofilm was left to accumulate over the restored slabs, and in the other side dental slabs were brushed, to allow biofilm removal. There was an extraoral application of 20% sucrose solution (8x/day over the enamel slabs. The formation of caries lesions (white spots was evaluated by visual inspection under stereomicroscopy. Additionally, the dental slabs were sectioned and observed under polarized light microscopy. Data were submitted to Kruskal-Wallis test and Spearman's correlation test at 5% significance level. Polishing and bonding were not significant factors regarding white spot formation (p>0.05. Biofilm control (brushing was associated with reduction of caries formation close to the restorations (p<0.01. Polarized light microscopy confirmed the visual inspection findings. These results suggest that while microleakage and surface roughness did not influence caries lesion formation, biofilm control may prevent the enamel demineralization.

  1. Chemical and morphological features of nanofilled composite resin: influence of finishing and polishing procedures and fluoride solutions.

    Science.gov (United States)

    de Oliveira, Ana Luísa Botta Martins; Domingos, Patrícia Aleixo Dos Santos; Palma-Dibb, Regina Guenka; Garcia, Patrícia Petromilli Nordi Sasso

    2012-02-01

    This study evaluated the influence of finishing and polishing procedures and different fluoride solutions on superficial morphology and chemistry of the nanofilled composite resin Supreme XT (3M) through the EDX analysis and SEM evaluation. Circular specimens (n = 30) of 10 mm diameter and 2 mm thickness were prepared, with half of the sample assays finished and polished with Super-Snap® sandpaper. The experimental groups were divided according to the presence or absence of finishing and polishing and solutions (artificial saliva, 0.05% of manipulated sodium fluoride solution, Fluordent Reach, Oral B, Fluorgard). Specimens were immersed in each respective solution for 1 min per day, during 60 days and stored in artificial saliva at 37 ± 1°C between immersion periods. Topography and chemical analysis was qualitative. It was observed that specimens submitted to finishing and polishing procedures had lower superficial degradation. Fluoride solutions promoted superficial alterations on specimens, being the highest degradation obtained with Fluordent Reach. It can be concluded that finishing and polishing procedures and the immersion media influence the superficial morphology of composite resin tested; the Fluordent Reach was the fluoride solution that most affected the material's surface.

  2. Influence of microleakage, surface roughness and biofilm control on secondary caries formation around composite resin restorations: an in situ evaluation.

    Science.gov (United States)

    Lima, Fábio Garcia; Romano, Ana Regina; Correa, Marcos Britto; Demarco, Flávio Fernando

    2009-01-01

    This study was carried out to evaluate in situ the influence of microleakage, surface roughness and biofilm control on caries formation around composite resin restorations. During 28 days, 12 volunteers wore palatal devices containing bovine enamel slabs restored with composite resin. Restorations were made without leakage, when the adhesive system was applied, or with leakage, when adhesive system was omitted. Half of the restorations in each group were finished and the remaining were finished and polished. In one side of the palatal device, biofilm was left to accumulate over the restored slabs, and in the other side dental slabs were brushed, to allow biofilm removal. There was an extraoral application of 20% sucrose solution (8x/day) over the enamel slabs. The formation of caries lesions (white spots) was evaluated by visual inspection under stereomicroscopy. Additionally, the dental slabs were sectioned and observed under polarized light microscopy. Data were submitted to Kruskal-Wallis test and Spearman's correlation test at 5% significance level. Polishing and bonding were not significant factors regarding white spot formation (p>0.05). Biofilm control (brushing) was associated with reduction of caries formation close to the restorations (p<0.01). Polarized light microscopy confirmed the visual inspection findings. These results suggest that while microleakage and surface roughness did not influence caries lesion formation, biofilm control may prevent the enamel demineralization.

  3. The Influence of Mo Additive on the Microstructure and Property of Ti/Al2O3 Composite

    Institute of Scientific and Technical Information of China (English)

    WANG Zhi; LI Ming-ling; SHEN Qiang; ZHANG Lian-meng

    2003-01-01

    The influence of Mo on the microstructure, bending strength and HV of Ti/Al2O3 composite was studied, and the influence mechanism was analyzed . The results indicate that after the addition of Mo, the composite organization is finer and phases distribution is better-proportioned which make the microstructure denser , the bending strength and HV of composite are also increased to a degree . But the bending strength inceases first then decreases with the increasing of Mo content, so the appropriate Mo content for the Ti/Al2O3 composite is to be further confirmed.

  4. The influence of the cavity preparation design on marginal accuracy of laboratory-processed resin composite restorations.

    Science.gov (United States)

    Fonseca, Rodrigo Borges; Correr-Sobrinho, Lourenço; Fernandes-Neto, Alfredo Júlio; Quagliatto, Paulo Sérgio; Soares, Carlos José

    2008-03-01

    The aim of this study was to evaluate the influence of different cavity preparation designs on marginal accuracy of laboratory-processed resin composite restored teeth. Eighty mandibular human third molars were selected. There were two experimental factors, occlusal isthmus width (narrow vs wide) and cuspal coverage (inlay, one-cusp onlay, two-cusp onlay, and all-cusp onlay), resulting on eight groups (N = 10). Indirect composite restorations (SR Adoro, Ivoclar-Vivadent) were manufactured and positioned over each respective preparation. Marginal accuracy evaluation was accomplished using a stereomicroscope at three points on buccal, lingual, mesial, and distal regions with 40x magnification. The results showed significant differences (P = 0.00) with wide inlay showing the best overall marginal accuracy and narrow inlay the worst one. Two-way analysis of variance (ANOVA) showed significant differences when considering the factor occlusal isthmus width (P = 0.00). In general, preparations with wide occlusal isthmus presented better results than narrow ones, except for wide all-cusp onlays; however, the test failed to show differences when considering the cuspal coverage (P = 0.42) or the interaction between both factors (P = 0.30). The effect of occlusal width extension on marginal accuracy of indirect composite resin restorations is significant, with lower values of gaps width in wide preparations, but since in a clinical situation this would mean greater removal of sound tooth structure, less-aggressive preparations combined with other restorative procedures seem to be more feasible.

  5. Influence of Sealer and Light-Curing Units on Push-Out Bond Strength Of Composite Resin to Weakened Roots.

    Science.gov (United States)

    Lima, Adriana Corrêa de; Rached-Junior, Fuad Jacob; Faria, Natália Spadini de; Messias, Danielle Cristine; Chaves, Carolina de Andrade Lima; Freitas, Jessica Vavassori de; Baratto-Filho, Flares; Silva-Sousa, Yara Teresinha Corrêa

    2016-01-01

    The aim of this study was to assess the influence of sealer and light-curing unit on regional bond strength of resin composite to the weakened roots. Ninety roots of incisors were experimentally weakened, subjected to biomechanical preparation and filled with either Endofill, AH Plus or MTA Fillapex The roots were desobturated e reinforced with resin composite and fiber post light-activated with one of the light sources: halogen at 600 mW/ cm2 (QTH-600), LED at 800 mW/ cm2 (LED-800) and LED at 1500 mW/ cm2 (LED-1500). The roots were sectioned in slices from cervical, middle and apical root-reinforcement regions and analyzed by push out test, scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Bond strength data were analyzed using three-way ANOVA and Tukey´s test (α=0.05). Specimens filled with AH Plus had higher bond strength, followed by MTA Fillapex and Endofill (pfilling material in the dentinal tubules for all groups. The eugenol-containing sealer (Endofill) compromised the push-out bond strength of composite resin to the root dentin. Bond strength was favored in the cervical region, and when LED-1500 was used.

  6. The influence of snakehead (Channa striata) fish extract to increase hyperglycemic mice fertility based on spermatogenic cell composition

    Science.gov (United States)

    Hidayati, Dewi; Abdulgani, Nurlita; Ashuri, Nova Maulidina; Sa'adah, Noor Nailis; Lukitasari, Maharani

    2017-06-01

    Reproductive dysfunction is recognized as a consequence of diabetes mellitus. Previous study revealed that snakehead (Channa striata) fish extract can repairing the pancreas histological structure which by that decreasing the blood glucose levels. Further research was conducted to determine the influence of snakehead fish extract (SHFE) to increasing the fertility of hyperglycemic mice based on spermatogenic cell composition. Twenty five adult mice (Mus musculus) were induced intraperitoneally to be hyperglycemic using alloxan monohydrate single dose of 190 mg/kg body weight. Hyperglycemic mice treated orally for 14 days using SHFE which grouped into five treatment dosages. Testicular histology were prepared using the paraffin methods and stained with Haematoxylin and Eosin. According to ANOVA and Tukey's test, it was found that spermatogenic cells population as well as its composition in the testis of mice that treated with SHFE are significantly higher than hyperglichemic mice. The highest dose of SHFE (0.15 ml/day), showed highest spermatogenic cell. All hyperglichemic mice that treated with SHFE exhibited the ratio composition of spermatogonia: spermatocytes: spermatids as same as with control (healthy mice) i.e. 1:1:3 respectively.

  7. Modelling the influence of steel fibres on the electrical resistivity of cementitious composites

    DEFF Research Database (Denmark)

    Solgaard, Anders Ole Stubbe; Michel, Alexander; Stang, Henrik

    2009-01-01

    work concerns the electrical resistivity of cementitious composites and some of the parameters influencing it in order to get a more thorough understanding of the factors governing the overall resistivity. The basis of the present study is an experimental investigation of the electrical resistivity...... the overall resistivity of the material and thereby the corrosion rate of the embedded reinforcement. To the knowledge of the authors, only preliminary studies have been made on the influence of corrosion of the reinforcement bars from the addition of the electrical conductive steel fibres. Thus the present......One of the governing factors on the corrosion of embedded reinforcement is the electrical resistivity of the concrete. The combination of steel fibres and conventional reinforcement bars has been used in a number of structures. However, the addition of electrical con-ductive fibres might influence...

  8. Influence of composition on microstructural parameters of single crystal nickel-base superalloys

    Energy Technology Data Exchange (ETDEWEB)

    MacKay, R.A., E-mail: Rebecca.A.MacKay@nasa.gov [NASA Glenn Research Center, 21000 Brookpark Rd., Cleveland, Ohio 44135 (United States); Gabb, T.P. [NASA Glenn Research Center, 21000 Brookpark Rd., Cleveland, Ohio 44135 (United States); Garg, A. [NASA Glenn Research Center, 21000 Brookpark Rd., Cleveland, Ohio 44135 (United States); University of Toledo, 2801 W. Bancroft, Toledo, Ohio 43606 (United States); Rogers, R.B.; Nathal, M.V. [NASA Glenn Research Center, 21000 Brookpark Rd., Cleveland, Ohio 44135 (United States)

    2012-08-15

    Fourteen nickel-base superalloy single crystals containing a range of chromium (Cr), cobalt (Co), molybdenum (Mo), and rhenium (Re) levels, and fixed amounts of aluminum (Al) and tantalum (Ta), were examined to determine the effect of bulk composition on basic microstructural parameters, including {gamma} Prime solvus, {gamma} Prime volume fraction, topologically close-packed (TCP) phases, {gamma} and {gamma} Prime phase chemistries, and {gamma}-{gamma} Prime lattice mismatch. Regression models describing the influence of bulk alloy composition on each of the microstructural parameters were developed and compared to predictions by a commercially-available software tool that used computational thermodynamics. Co produced the largest change in {gamma} Prime solvus over the wide compositional range explored and Mo produced the biggest effect on the {gamma} lattice parameter over its range, although Re had a very potent influence on all microstructural parameters investigated. Changing the Cr, Co, Mo, and Re contents in the bulk alloy had an impact on their concentrations in the {gamma} matrix and to a smaller extent in the {gamma} Prime phase. The software tool under-predicted {gamma} Prime solvus temperatures and {gamma} Prime volume fractions, and over-predicted TCP phase volume fractions at 982 Degree-Sign C. However, the statistical regression models provided excellent estimations of the microstructural parameters and demonstrated the usefulness of such formulas. - Highlights: Black-Right-Pointing-Pointer Effects of Cr, Co, Mo, and Re on microstructure in new low density superalloys Black-Right-Pointing-Pointer Co produced a large change in {gamma} Prime solvus; Mo had a large effect on lattice mismatch. Black-Right-Pointing-Pointer Re exhibited very potent influence on all microstructural parameters was investigated. Black-Right-Pointing-Pointer {gamma} and {gamma} Prime phase chemistries both varied with temperature and alloy composition. Black

  9. Influence of Mining Thickness on the Rationality of Upward Mining in Coal Seam Group

    Directory of Open Access Journals (Sweden)

    Y. Li

    2016-04-01

    Full Text Available This study aimed to determine the influence of mining thickness on the rationality of upward mining in coal seam group. Numerical simulation and theoretical analysis were performed to investigate the influence of the mining thicknesses of initial mining seam on the destruction and pressure relief effect of the upper coal seam in a high-gas coal seam group. The mechanical model of the roof failure based on the mining thickness was established by assuming that the gob formed after adjacent panels have fully been caved is the infinite plane. On the basis of this model, an equation was derived to calculate the roof failure height of the panel. Considering the geological conditions of No. 9 and No. 12 coal seams of Zhaogezhuang Coal Mine, economic effectiveness, and proposed techniques, we concluded that the top layer (4 m of the No. 12 coal seam should be mined first. The top layer of the No. 9 coal seam should be subsequently mined. The topcaving technique was applied to the exploitation of the lower layer of the No. 12 coal seam. Practically monitored data revealed that the deformation and failure of the No. 2699 panel roadway was small and controllable, the amount of gas emission was reduced significantly, and the effect of upward mining was active. The results of this study provide theory basics for mine designing, and it is the provision of a reference for safe and efficient coal exploitation under similar conditions.

  10. The influence of cavity preparation design on fracture strength and mode of fracture of laboratory-processed composite resin restorations.

    Science.gov (United States)

    Fonseca, Rodrigo Borges; Fernandes-Neto, Alfredo Julio; Correr-Sobrinho, Lourenco; Soares, Carlos Jose

    2007-10-01

    Removal of large amounts of sound tooth structure may result in a weakened restored tooth. Nevertheless, removal of tooth structure for cuspal coverage has been recommended to protect teeth restored with laboratory-processed composite resin (LPCR) from fracture. The purpose of this study was to evaluate the influence of different cavity preparation designs on fracture strength and modes of fracture of teeth restored with LPCR. Ninety anatomically similar human third mandibular molars were selected. There were 2 experimental factors, occlusal isthmus width (narrow versus wide) and cuspal coverage (inlay, 1-cusp onlay, 2-cusp onlay, and all-cusp onlay), and 1 control group that received no treatment, resulting in 9 groups (n=10). Indirect composite resin (SR Adoro) restorations were manufactured and adhesively cemented with Adper Single Bond 2 and Rely-X ARC. A compressive loading test (0.5 mm/min) was performed. The modes of fracture were classified according to 4 categories. One-way and 2-way ANOVA followed by Tukey-HSD test were used to statistically analyze the fracture load data (alpha =.05). The statistical analysis failed to show significant differences among restored groups but showed differences between these groups and the control group (P = .001). Two-way ANOVA failed to show any difference when considering the occlusal isthmus width alone (P = .98), cuspal coverage (P = .273), or the interaction between these factors (P = .972). Several teeth had fractures affecting a great amount of both restoration and tooth structure. This in vitro study showed restored teeth having similar fracture strength and fracture modes, suggesting that with the tested preparation designs, there is no advantage of cuspal coverage to protect LPCR restored teeth from fracture.

  11. Influence of in situ post-bleaching times on resin composite shear bond strength to enamel and dentin.

    Science.gov (United States)

    Barbosa, Cinthia Maria; Sasaki, Robson Tetsuo; Flório, Flávia Martão; Basting, Roberta Tarkany

    2009-12-01

    To evaluate in situ the influence of time after treatment with a 16% carbamide peroxide home-use bleaching agent on the shear bond strength of resin-based composite to human enamel and dentin. 80 enamel slabs (E) and 80 dentin slabs (D) were obtained, embedded, flattened, sterilized and randomly fixed on the buccal surface of teeth in 20 volunteers. These specimens were submitted to treatment with a 16% carbamide peroxide bleaching agent (Pola Night) for 2 hours a day, for 3 weeks. The control group (C) consisted of slabs that were fixed on buccal tooth faces that did not receive any bleaching treatment. For the experimental groups, three slabs of E and three slabs of D were fixed to teeth of the same volunteers, and after bleaching treatment, the slabs were removed at different times: EI--immediate removal; E7--removal 7 days after treatment ended; E14--removal 14 days after treatment ended. After removal, the slabs were again embedded and microhybrid composite resin cylinders (Filtek Z250) were constructed and bonded using a one-bottle adhesive system (Single Bond) for shear bond strength tests. These tests were performed in a universal testing machine, with a speed of 0.5 mm/minute, with the data returned in MPa. The results were submitted to the ANOVA test. There were no significant differences with regards to the timespan for the E and D groups (P > 0.05). For the fracture mode analysis, there was a predominance of adhesive failures for Groups C, EI and E14 in enamel, with the same adhesive failures occurred for all groups in dentin. It was concluded that restorative procedures may be performed immediately after the end of the bleaching treatment.

  12. Differential School Effects among Low, Middle, and High Social Class Composition Schools: A Multiple Group, Multilevel Latent Growth Curve Analysis

    Science.gov (United States)

    Palardy, Gregory J.

    2008-01-01

    This study uses large-scale survey data and a multiple group, multilevel latent growth curve model to examine differential school effects between low, middle, and high social class composition public schools. The results show that the effects of school inputs and school practices on learning differ across the 3 subpopulations. Moreover, student…

  13. Differential School Effects among Low, Middle, and High Social Class Composition Schools: A Multiple Group, Multilevel Latent Growth Curve Analysis

    Science.gov (United States)

    Palardy, Gregory J.

    2008-01-01

    This study uses large-scale survey data and a multiple group, multilevel latent growth curve model to examine differential school effects between low, middle, and high social class composition public schools. The results show that the effects of school inputs and school practices on learning differ across the 3 subpopulations. Moreover, student…

  14. Attitudes, Behaviors, and Effectiveness of Black and White Leaders of Simulated Problem Solving Groups of Varying Size and Racial Composition.

    Science.gov (United States)

    Hill, Walter A.; Allen, William R.

    A field experiment was used to investigate the effects, if any, of changing group size and racial composition on the attitudes, behaviors, and effectiveness of black and white leaders. Subjects were 288 naval recruits, half black and half white, performing two tasks which were watched by a pair of racially mixed observers through a one-way mirror.…

  15. The influence of pendant hydroxyl groups on enzymatic degradation and drug delivery of amphiphilic poly[glycidol-block-(epsilon-caprolactone)] copolymers.

    Science.gov (United States)

    Mao, Jing; Gan, Zhihua

    2009-11-10

    An amphiphilic diblock copolymer PG-b-PCL with well-controlled structure and pendant hydroxyl groups along hydrophilic block was synthesized by sequential anionic ring-opening polymerization. The micellization and drug release of PG-b-PCL copolymers using pyrene as a fluorescence probe were investigated for determining the influences of copolymer composition and lipase concentration on drug loading capacity and controlled release behavior. The biodegradation of PG-b-PCL copolymers was studied with microspheres as research samples. It has been concluded that the polar hydroxyl groups along each repeat unit of hydrophilic PG block in PG-b-PCL copolymer have great influences on drug encapsulation, drug release, and enzymatic degradation of micelles and microspheres.

  16. Influence of dispersants on aging and frost elastomeric compositions based on butadiene acrylonitrile rubbers

    Directory of Open Access Journals (Sweden)

    R. M. Dolinskaya

    2016-01-01

    Full Text Available The possibility of use of dispergators of various nature for production of rubber technical products with expanded temperature conditions of operation is studied. It is investigated influences of dispergators of Dispergator FL and INT 159 on properties of rubber mixes for receiving products with high resistance to thermal aging or frost resistance. Research of influence of modifiers was conducted for rubber mixes on the basis of butadienenitrile rubbers synthetic (BNRS-18 and BNRS-28. I’s established that at addition of a dispergator of Dispergator FL the indicator of relative deformatstion of compression (RDC and respectively heat stability of rubbers increases. Introduction to structure of elastomeric composition of a dispergator of INT 159 practically doesn’t influence frost resistance, and Dispergator FL worsens her (the coefficient of frost resistance decreases by 15.4–17.8%. Possibly it is connected with the fact that at the lowered temperatures in the presence of Dispergator FL there is a bigger delay of relaxation processes and decrease in energy of the thermal movement of links of macromolecules of rubbers. It becomes insufficient for overcoming of intermolecular interaction in the modified system and commission of conformational transitions of macromolecules under the influence of external loading. Mechanical energy is to a large extent mentioned not on change of a form of macromolecules, and on their mechanodestruction. However, it increases heat stability since it that is higher, than molecular mobility is lower. INT 159 dispergator components, settling down on borders of supramolecular formations of elastomers, increase mobility of links of macromolecules of rubbers, weaken chemical bonds in them, reduce thermal stability, but at the same time INT 159 dispergator practically doesn’t reduce frost resistance therefore it is expedient to apply it when receiving frost-resistant elastomeric composition. Thus, when receiving

  17. Leaf wax composition and carbon isotopes vary among major conifer groups

    Science.gov (United States)

    Diefendorf, Aaron F.; Leslie, Andrew B.; Wing, Scott L.

    2015-12-01

    Leaf waxes (e.g. n-alkanes, n-alkanoic acids) and their carbon isotopes (δ13C) are commonly used to track past changes in the carbon cycle, water availability, and plant ecophysiology. Previous studies indicated that conifers have lower n-alkane concentrations than angiosperms and that 13C fractionation during n-alkane synthesis (εn-alkane) is smaller than in angiosperms. These prior studies, however, sampled a limited phylogenetic and geographic subset of conifers, leaving out many important subtropical and Southern Hemisphere groups that were once widespread and common components of fossil assemblages. To expand on previous work, we collected 43 conifer species (and Ginkgo biloba) from the University of California Botanical Garden at Berkeley, sampling all extant conifer families and almost two-thirds of extant genera. We find that Pinaceae, including many North American species used in previous studies, have very low or no n-alkanes. However, other conifer groups have significant concentrations of n-alkanes, especially Southern Hemisphere Araucariaceae and Podocarpaceae (monkey puzzles, Norfolk Island pines, and yellowwoods), and many species of Cupressaceae (junipers and relatives). Within the Cupressaceae, we find total n-alkane concentrations are high in subfamilies Cupressoideae and Callitroideae, but significantly lower in the early diverging taxodioid lineages (including bald cypress and redwood). Individual n-alkane chain lengths have a weak phylogenetic signal, except for n-C29 alkane, but when combined using average chain length (ACL), a strong phylogenetic signal emerges. The strong phylogenetic signal in ACL, observed in the context of a common growth environment for all plants we sampled, suggests that ACL is strongly influenced by factors other than climate. An analysis of εn-alkane indicates a strong phylogenetic signal in which the smallest biosynthetic fractionation occurs in Pinaceae and the largest in Taxaceae (yews and relatives). The

  18. Composites

    Science.gov (United States)

    Chmielewski, M.; Nosewicz, S.; Pietrzak, K.; Rojek, J.; Strojny-Nędza, A.; Mackiewicz, S.; Dutkiewicz, J.

    2014-11-01

    It is commonly known that the properties of sintered materials are strongly related to technological conditions of the densification process. This paper shows the sintering behavior of a NiAl-Al2O3 composite, and its individual components sintered separately. Each kind of material was processed via the powder metallurgy route (hot pressing). The progress of sintering at different stages of the process was tested. Changes in the microstructure were examined using scanning and transmission electron microscopy. Metal-ceramics interface was clean and no additional phases were detected. Correlation between the microstructure, density, and mechanical properties of the sintered materials was analyzed. The values of elastic constants of NiAl/Al2O3 were close to intermetallic ones due to the volume content of the NiAl phase particularly at low densities, where small alumina particles had no impact on the composite's stiffness. The influence of the external pressure of 30 MPa seemed crucial for obtaining satisfactory stiffness for three kinds of the studied materials which were characterized by a high dense microstructure with a low number of isolated spherical pores.

  19. The influence of beverage composition on delivery of phenolic compounds from coffee and tea.

    Science.gov (United States)

    Ferruzzi, Mario G

    2010-04-26

    Epidemiological data suggest that consumption of coffee and tea is associated with a reduced risk of several chronic and degenerative diseases including cardiovascular disorders, diabetes, obesity and neurodegenerative disorders. Both coffee and tea are a rich source of phenolic compounds including chlorogenic acids in coffee; and flavan-3-ols as well as complex theaflavins and thearubigens in tea. Coffee and tea are two of the most commonly consumed beverages in the world and thus represent a significant opportunity to positively affect disease risk and outcomes globally. Central to this opportunity is a need to better understand factors that may affect the bioavailability of specific phenolic components from coffee and tea based beverages. An overview of the phenolic composition of coffee and tea is discussed in the context of how processing and composition might influence phenolic profiles and bioavailability of individual phenolic components. Specifically, the impact of beverage formulation, the extent and type of processing and the influence of digestion on stability, bioavailability and metabolism of bioactive phenolics from tea and coffee are discussed. The impact of co-formulation with ascorbic acid and other phytochemicals are discussed as strategies to improve absorption of these health promoting phytochemicals. A better understanding of how the beverage composition impacts phenolic profiles and their bioavailability is critical to development of beverage products designed to deliver specific health benefits. Copyright 2010 Elsevier Inc. All rights reserved.

  20. Influence of weave structures on the tribological properties of hybrid Kevlar/PTFE fabric composites

    Science.gov (United States)

    Gu, Dapeng; Yang, Yulin; Qi, Xiaowen; Deng, Wei; Shi, Lei

    2012-09-01

    The existing research of the woven fabric self-lubricating liner mainly focus on the tribological performance improvements and the service life raised by changing different fiber type combinations, adding additive modification, and performing fiber surface modification. As fabric composites, the weave structures play an important role in the mechanical and tribological performances of the liners. However, hardly any literature is available on the friction and wear behavior of such composites with different weave structures. In this paper, three weave structures (plain, twill 1/3 and satin 8/5) of hybrid Kevlar/PTFE fabric composites are selected and pin-on-flat linear reciprocating wear studies are done on a CETR tester under different pressures and different frequencies. The relationship between the tensile strength and the wear performance are studied. The morphologies of the worn surfaces under the typical test conditions are analyzed by means of scanning electron microscopy (SEM). The analysis results show that at 10 MPa, satin 8/5 performs the best in friction-reduction and antiwear performance, and plain is the worst. At 30 MPa, however, the antiwear performance is reversed and satin 8/5 does not even complete the 2 h wear test at 16 Hz. There is no clear evidence proving that the tensile strength has an influence on the wear performance. So the different tribological performance of the three weave structures of fabric composites may be attributed to the different PTFE proportions in the fabric surface and the different wear mechanisms. The fabric composites are divided into three regions: the lubrication region, the reinforced region and the bonding region. The major mechanisms are fatigue wear and the shear effects of the friction force in the lubrication region. In the reinforced region fiber-matrix de-bonding and fiber breakage are involved. The proposed research proposes a regional wear model and further indicates the wear process and the wear mechanism

  1. Influence of different restorative techniques on marginal seal of class II composite restorations

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    Sinval Adalberto Rodrigues Junior

    2010-02-01

    Full Text Available OBJECTIVE: To evaluate the gingival marginal seal in class II composite restorations using different restorative techniques. MATERIAL AND METHODS: Class II box cavities were prepared in both proximal faces of 32 sound human third molars with gingival margins located in either enamel or dentin/cementum. Restorations were performed as follows: G1 (control: composite, conventional light curing technique; G2: composite, soft-start technique; G3: amalgam/composite association (amalcomp; and G4: resin-modified glass ionomer cement/composite, open sandwich technique. The restored specimens were thermocycled. Epoxy resin replicas were made and coated for scanning electron microscopy examination. For microleakage evaluation, teeth were coated with nail polish and immersed in dye solution. Teeth were cut in 3 slices and dye penetration was recorded (mm, digitized and analyzed with Image Tool software. Microleakage data were analyzed statistically by non-parametric Kruskal-Wallis and Mann-Whitney tests. RESULTS: Leakage in enamel was lower than in dentin (p<0.001. G2 exhibited the lowest leakage values (p<0.05 in enamel margins, with no differences between the other groups. In dentin margins, groups G1 and G2 had similar behavior and both showed less leakage (p<0.05 than groups G3 and G4. SEM micrographs revealed different marginal adaptation patterns for the different techniques and for the different substrates. CONCLUSION: The soft-start technique showed no leakage in enamel margins and produced similar values to those of the conventional (control technique for dentin margins.

  2. The influence of tree species composition on the storage and mobility of semivolatile organic compounds in forest soils

    Energy Technology Data Exchange (ETDEWEB)

    Komprdová, Klára, E-mail: komprdova@recetox.muni.cz [RECETOX (Research Centre for Toxic Compounds in the Environment), Kamenice 753/5, CZ-625 00 Brno (Czech Republic); Komprda, Jiří [RECETOX (Research Centre for Toxic Compounds in the Environment), Kamenice 753/5, CZ-625 00 Brno (Czech Republic); Menšík, Ladislav [Mendel University in Brno, Faculty of Forestry and Wood Technology, Zemědělská 3, Brno 613 00 (Czech Republic); Vaňková, Lenka [RECETOX (Research Centre for Toxic Compounds in the Environment), Kamenice 753/5, CZ-625 00 Brno (Czech Republic); Kulhavý, Jiří [Mendel University in Brno, Faculty of Forestry and Wood Technology, Zemědělská 3, Brno 613 00 (Czech Republic); Nizzetto, Luca [RECETOX (Research Centre for Toxic Compounds in the Environment), Kamenice 753/5, CZ-625 00 Brno (Czech Republic); Norwegian Institute for Water Research, Gaustadalleen 21, NO-0349 Oslo (Norway)

    2016-05-15

    Soil contamination with PCBs and PAHs in adjacent forest plots, characterized by a distinct composition in tree species (spruce only, mixed and beech only), was analyzed to investigate the influence of ecosystem type on contaminant mobility in soil under very similar climate and exposure conditions. Physical-chemical properties and contaminant concentrations in litter (L), organic (F, H) and mineral (A, B) soil horizons were analyzed. Contaminant distribution in the soil core varied both in relation to forest type and contaminant group/properties. Contaminant mobility in soil was assessed by examining the ratios of total organic carbon (TOC)-standardized concentrations across soil horizons (Enrichment factors, EF{sub TOC}) and the relationship between EF{sub TOC} and the octanol-water equilibrium partitioning coefficient (K{sub OW}). Contaminant distribution appeared to be highly unsteady, with pedogenic/biogeochemical drivers controlling contaminant mobility in organic layers and leaching controlling accumulation in mineral layers. Lighter PCBs displayed higher mobility in all forest types primarily controlled by leaching and, to a minor extent, diffusion. Pedogenic processes controlling the formation of soil horizons were found to be crucial drivers of PAHs and heavier PCBs distribution. All contaminants appeared to be more mobile in the soil of the broadleaved plot, followed by mixed canopy and spruce forest. Increasing proportion of deciduous broadleaf species in the forest can thus lead to faster degradation or the faster leaching of PAHs and PCBs. The composition of humic substances was found to be a better descriptor of contaminant concentration than TOC. - Highlights: • Tree species composition influences vertical distribution of PCBs and PAHs in soils. • PCBs and PAHs were more mobile in the soil of the broadleaved plot. • Low molecular weight PCBs displayed higher mobility in all forest types. • Humic substances were important descriptors of

  3. ABO, Secretor and Lewis histo-blood group systems influence the digestive form of Chagas disease.

    Science.gov (United States)

    Bernardo, Cássia Rubia; Camargo, Ana Vitória Silveira; Ronchi, Luís Sérgio; de Oliveira, Amanda Priscila; de Campos Júnior, Eumildo; Borim, Aldenis Albaneze; Brandão de Mattos, Cinara Cássia; Bestetti, Reinaldo Bulgarelli; de Mattos, Luiz Carlos

    2016-11-01

    Chagas disease, caused by Trypanosoma cruzi, can affect the heart, esophagus and colon. The reasons that some patients develop different clinical forms or remain asymptomatic are unclear. It is believed that tissue immunogenetic markers influence the tropism of T. cruzi for different organs. ABO, Secretor and Lewis histo-blood group systems express a variety of tissue carbohydrate antigens that influence the susceptibility or resistance to diseases. This study aimed to examine the association of ABO, secretor and Lewis histo-blood systems with the clinical forms of Chagas disease. We enrolled 339 consecutive adult patients with chronic Chagas disease regardless of gender (cardiomyopathy: n=154; megaesophagus: n=119; megacolon: n=66). The control group was composed by 488 healthy blood donors. IgG anti-T. cruzi antibodies were detected by ELISA. ABO and Lewis phenotypes were defined by standard hemagglutination tests. Secretor (FUT2) and Lewis (FUT3) genotypes, determined by Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), were used to infer the correct histo-blood group antigens expressed in the gastrointestinal tract. The proportions between groups were compared using the χ2 test with Yates correction and Fisher's exact test and the Odds Ratio (OR) and 95% Confidence Interval (95% CI) were calculated. An alpha error of 5% was considered significant with p-values ABO (X(2): 2.635; p-value=0.451), Secretor (X(2): 0.056; p-value=0.812) or Lewis (X(2): 2.092; p-value=0.351) histo-blood group phenotypes between patients and controls. However, B plus AB Secretor phenotypes were prevalent in pooled data from megaesophagus and megacolon patients (OR: 5.381; 95% CI: 1.230-23.529; p-value=0.011; pc=0.022) in comparison to A plus O Secretor phenotypes. The tissue antigen variability resulting from the combined action of ABO and Secretor histo-blood systems is associated with the digestive forms of Chagas disease. Copyright © 2016 Elsevier B

  4. Diversity and composition of vaginal microbiota of pregnant women at risk for transmitting Group B Streptococcus treated with intrapartum penicillin.

    Science.gov (United States)

    Roesch, Luiz Fernando Wurdig; Silveira, Rita C; Corso, Andréa L; Dobbler, Priscila Thiago; Mai, Volker; Rojas, Bruna S; Laureano, Álvaro M; Procianoy, Renato S

    2017-01-01

    Administering intravenous antibiotics during labor to women at risk for transmitting Group B Streptococcus (GBS) can prevent infections in newborns. However, the impact of intrapartum antibiotic prophylaxis on mothers' microbial community composition is largely unknown. We compared vaginal microbial composition in pregnant women experiencing preterm birth at ≤ 32 weeks gestation that received intrapartum antibiotic prophylaxis with that in controls. Microbiota in vaginal swabs collected shortly before delivery from GBS positive women that received penicillin intravenously during labor or after premature rupture of membranes was compared to controls. Microbiota was analyzed by 16S rRNA sequencing using the PGM Ion Torrent to determine the effects of penicillin use during hospitalization and GBS status on its composition. Penicillin administration was associated with an altered vaginal microbial community composition characterized by increased microbial diversity. Lactobacillus sp. contributed only 13.1% of the total community in the women that received penicillin compared to 88.1% in the controls. Streptococcus sp. were present in higher abundance in GBS positive woman compared to controls, with 60% of the total vaginal microbiota in severe cases identified as Streptococcus sp. Vaginal communities of healthy pregnant women were dominated by Lactobacillus sp. and contained low diversity, while Group B Streptococcus positive women receiving intrapartum antibiotic prophylaxis had a modified vaginal microbiota composition with low abundance of Lactobacillus but higher microbial diversity.

  5. Diversity and composition of vaginal microbiota of pregnant women at risk for transmitting Group B Streptococcus treated with intrapartum penicillin

    Science.gov (United States)

    Roesch, Luiz Fernando Wurdig; Silveira, Rita C.; Corso, Andréa L.; Dobbler, Priscila Thiago; Mai, Volker; Rojas, Bruna S.; Laureano, Álvaro M.; Procianoy, Renato S.

    2017-01-01

    Background Administering intravenous antibiotics during labor to women at risk for transmitting Group B Streptococcus (GBS) can prevent infections in newborns. However, the impact of intrapartum antibiotic prophylaxis on mothers’ microbial community composition is largely unknown. We compared vaginal microbial composition in pregnant women experiencing preterm birth at ≤ 32 weeks gestation that received intrapartum antibiotic prophylaxis with that in controls. Methods Microbiota in vaginal swabs collected shortly before delivery from GBS positive women that received penicillin intravenously during labor or after premature rupture of membranes was compared to controls. Microbiota was analyzed by 16S rRNA sequencing using the PGM Ion Torrent to determine the effects of penicillin use during hospitalization and GBS status on its composition. Results Penicillin administration was associated with an altered vaginal microbial community composition characterized by increased microbial diversity. Lactobacillus sp. contributed only 13.1% of the total community in the women that received penicillin compared to 88.1% in the controls. Streptococcus sp. were present in higher abundance in GBS positive woman compared to controls, with 60% of the total vaginal microbiota in severe cases identified as Streptococcus sp. Conclusions Vaginal communities of healthy pregnant women were dominated by Lactobacillus sp. and contained low diversity, while Group B Streptococcus positive women receiving intrapartum antibiotic prophylaxis had a modified vaginal microbiota composition with low abundance of Lactobacillus but higher microbial diversity. PMID:28178310

  6. Influence of Ultraviolet/Ozonolysis Treatment of Nanocarbon Filler on the Electrical Resistivity of Epoxy Composites.

    Science.gov (United States)

    Perets, Yulia; Matzui, Lyudmila; Vovchenko, Lyudmila; Ovsiienko, Irina; Yakovenko, Olena; Lazarenko, Oleksandra; Zhuravkov, Alexander; Brusylovets, Oleksii

    2016-12-01

    In the present work, we have investigated concentration and temperature dependences of electrical conductivity of graphite nanoplatelets/epoxy resin composites. The content of nanocarbon filler is varied from 0.01 to 0.05 volume fraction. Before incorporation into the epoxy resin, the graphite nanoplatelets were subjected to ultraviolet ozone treatment at 20-min ultraviolet exposure. The electric resistance of the samples was measured by two- or four-probe method and teraohmmeter E6-13. Several characterization techniques were employed to identify the mechanisms behind the improvements in the electrical properties, including SEM and FTIR spectrum analysis.It is established that the changes of the relative intensities of the bands in FTIR spectra indicate the destruction of the carboxyl group -COOH and group -OH. Electrical conductivity of composites has percolation character and graphite nanoplatelets (ultraviolet ozone treatment for 20 min) addition which leads to a decrease of percolation threshold 0.005 volume fraction and increase values of electrical conductivity (by 2-3 orders of magnitude) above the percolation threshold in comparison with composite materials-graphite nanoplatelets/epoxy resin. The changes of the value and behavior of temperature dependences of the electrical resistivity of epoxy composites with ultraviolet/ozone-treated graphite nanoparticles have been analyzed within the model of effective electrical conductivity. The model takes into account the own electrical conductivity of the filler and the value of contact electric resistance between the filler particles of the formation of continuous conductive pathways.

  7. The Influence of Culture on Agroecosystem Structure: A Comparison of the Spatial Patterns of Homegardens of Different Ethnic Groups in Thailand and Vietnam.

    Directory of Open Access Journals (Sweden)

    Pijika Timsuksai

    Full Text Available Different ethnic groups have evolved distinctive cultural models which guide their interactions with the environment, including their agroecosystems. Although it is probable that variations in the structures of homegardens among separate ethnic groups reflect differences in the cultural models of the farmers, empirical support for this assumption is limited. In this paper the modal horizontal structural patterns of the homegardens of 8 ethnic groups in Northeast Thailand and Vietnam are described. Six of these groups (5 speaking Tai languages and 1 speaking Vietnamese live in close proximity to each other in separate villages in Northeast Thailand, and 2 of the groups (one Tai-speaking and one Vietnamese-speaking live in different parts of Vietnam. Detailed information on the horizontal structure of homegardens was collected from samples of households belonging to each group. Although each ethnic group has a somewhat distinctive modal structure, the groups cluster into 2 different types. The Tai speaking Cao Lan, Kalaeng, Lao, Nyaw, and Yoy make up Type I while both of the Vietnamese groups, along with the Tai speaking Phu Thai, belong to Type II. Type I gardens have predominantly organic shapes, indeterminate boundaries, polycentric planting patterns, and multi-species composition within planting areas. Type II homegardens have geometric shapes, sharp boundaries, lineal planting patterns, and mono-species composition of planting areas. That the homegardens of most of the Tai ethnic groups share a relatively similar horizontal structural pattern that is quite different from the pattern shared by both of the Vietnamese groups suggests that the spatial layout of homegardens is strongly influenced by their different cultural models.

  8. The Influence of Culture on Agroecosystem Structure: A Comparison of the Spatial Patterns of Homegardens of Different Ethnic Groups in Thailand and Vietnam.

    Science.gov (United States)

    Timsuksai, Pijika; Rambo, A Terry

    2016-01-01

    Different ethnic groups have evolved distinctive cultural models which guide their interactions with the environment, including their agroecosystems. Although it is probable that variations in the structures of homegardens among separate ethnic groups reflect differences in the cultural models of the farmers, empirical support for this assumption is limited. In this paper the modal horizontal structural patterns of the homegardens of 8 ethnic groups in Northeast Thailand and Vietnam are described. Six of these groups (5 speaking Tai languages and 1 speaking Vietnamese) live in close proximity to each other in separate villages in Northeast Thailand, and 2 of the groups (one Tai-speaking and one Vietnamese-speaking) live in different parts of Vietnam. Detailed information on the horizontal structure of homegardens was collected from samples of households belonging to each group. Although each ethnic group has a somewhat distinctive modal structure, the groups cluster into 2 different types. The Tai speaking Cao Lan, Kalaeng, Lao, Nyaw, and Yoy make up Type I while both of the Vietnamese groups, along with the Tai speaking Phu Thai, belong to Type II. Type I gardens have predominantly organic shapes, indeterminate boundaries, polycentric planting patterns, and multi-species composition within planting areas. Type II homegardens have geometric shapes, sharp boundaries, lineal planting patterns, and mono-species composition of planting areas. That the homegardens of most of the Tai ethnic groups share a relatively similar horizontal structural pattern that is quite different from the pattern shared by both of the Vietnamese groups suggests that the spatial layout of homegardens is strongly influenced by their different cultural models.

  9. The influence of anthropometric factors on postural balance: the relationship between body composition and posturographic measurements in young adults

    Directory of Open Access Journals (Sweden)

    Angélica Castilho Alonso

    2012-12-01

    Full Text Available OBJECTIVE: The aim of the present study was to evaluate the influence of anthropometric characteristics and gender on postural balance in adults. One hundred individuals were examined (50 males, 50 females; age range 20-40 years. METHODS: The following body composition measurements were collected (using bone densitometry measurements: fat percentage (% fat, tissue (g, fat (g, lean mass (g, bone mineral content (g, and bone mineral density (g/cm2. In addition, the following anthropometric measurements were collected: body mass (kg, height (cm, length of the trunk-cephalic region (cm, length of the lower limbs (cm and length of the upper limbs (cm. The following indices were calculated: body mass index (kg/m², waist-hip ratio and the support base (cm². Also, a postural balance test was performed using posturography variables with open and closed eyes. RESULTS: The analysis revealed poor correlations between postural balance and the anthropometric variables. A multiple linear regression analysis demonstrated that the whole group (female and male height explained 12% of the medial-lateral displacement, 10% of the speed of oscillation, and 11% of the displacement area. The length of the trunk-cephalic length explained 6% of the displacement in the anteroposterior direction. With eyes closed, the support base and height explained 18% of the medial displacement, and the lateral height explained 10% of the displacement speed and 5% of the scroll area. CONCLUSION: Measured using posturography, the postural balance was only slightly influenced by the anthropometric variables, both with open and closed eyes. Height was the anthropometric variable that most influenced postural balance, both in the whole group and separately for each gender. Postural balance was more influenced by anthropometric factors in males than females.

  10. The influence of pomegranate by-product and punicalagins on selected groups of human intestinal microbiota.

    Science.gov (United States)

    Bialonska, Dobroslawa; Ramnani, Priya; Kasimsetty, Sashi G; Muntha, Kesava R; Gibson, Glenn R; Ferreira, Daneel

    2010-06-15

    We have examined the gut bacterial metabolism of pomegranate by-product (POMx) and major pomegranate polyphenols, punicalagins, using pH-controlled, stirred, batch culture fermentation systems reflective of the distal region of the human large intestine. Incubation of POMx or punicalagins with faecal bacteria resulted in formation of the dibenzopyranone-type urolithins. The time course profile confirmed the tetrahydroxylated urolithin D as the first product of microbial transformation, followed by compounds with decreasing number of phenolic hydroxy groups: the trihydroxy analogue urolithin C and dihydroxylated urolithin A. POMx exposure enhanced the growth of total bacteria, Bifidobacterium spp. and Lactobacillus spp., without influencing the Clostridium coccoides-Eubacterium rectale group and the C. histolyticum group. In addition, POMx increased concentrations of short chain fatty acids (SCFA) viz. acetate, propionate and butyrate in the fermentation medium. Punicalagins did not affect the growth of bacteria or production of SCFA. The results suggest that POMx oligomers, composed of gallic acid, ellagic acid and glucose units, may account for the enhanced growth of probiotic bacteria.

  11. Application of a central composite design to evaluate the influence of colouring agents in lipstick formulation.

    Science.gov (United States)

    Zibetti, F M; Cardoso, A C A; Desmarais, G C; de Almeida, K B; do Nascimento, L M; Rolim, L F; Rocha, M S; Duarte, N G D; Azevedo, P H R A; Araújo, J L; Mourão, S C; Falcão, D Q

    2016-10-01

    The aim of this study was to evaluate by central composite design the influence of colouring agents in lipstick colour, expressed by L*, a*, b* parameters (CIELab system) where L* indicates lightness, and a* and b* are the chromaticity coordinates. The a* indicates colour direction from red to green and b* from yellow to blue. Lipsticks were formulated as described by (Recent Adv. Prosp. Potent Med. Plants, 2009 and 39). The combined effect of three variables (dye, pigment and opacifier) was evaluated by different formulations in a central composite design. Colour parameters (L*, a*, b*) were analysed by reflectance spectrophotometry. Lipsticks were characterized by visual analyses and melting point. All formulations were integrate and homogeneous. The pigments and dye do not influence in colour transfer neither in melting point of lipsticks. On the other hand, results indicated that variables studied show influence only in parameter b*, whereas for L* and a* values there was no significant difference (P lipstick formulation, leading to the production of the colour ranging between violet and light red. Such results are useful for developing new lipstick formulations to obtain the desired colour in the final product. © 2016 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

  12. Photo-oxidation of EPDM/layered double hydroxides composites: Influence of layered hydroxides and stabilizers

    Directory of Open Access Journals (Sweden)

    2007-11-01

    Full Text Available The photo-oxidation of ethylene propylene diene monomer (EPDM/ layered double hydroxide (LDH composites as well as EPDM/LDH with stabilizers is studied under accelerated UV irradiation (λ≥290 nm at 60°C for different time intervals. The development of functional groups during oxidation was monitored by FT-IR spectroscopy. The photodegradation of the pristine polymer and composites take place and the increase in hydroxyl and carbonyl groups with irradiation times, was estimated. EPDM filled LDH showed higher degradation rate than pristine EPDM, while in acidic medium EPDM/LDH showed almost equal degradation as in isolated conditions. These results show the advantages of LDHs as a filler as well as an acid killer. The effect of stabilizers is very less because of their concentration in comparison of LDH.

  13. Influence of Composition on the Environmental Impact of a Cast Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    Patricia Gómez

    2016-05-01

    Full Text Available The influence of alloy composition on the environmental impact of the production of six aluminum casting alloys (Al Si12Cu1(Fe, Al Si5Mg, Al Si9Cu3Zn3Fe, Al Si10Mg(Fe, Al Si9Cu3(Fe(Zn and Al Si9 has been analyzed. In order to perform a more precise environmental impact calculation, Life Cycle Assessment (LCA with ReCiPe Endpoint methodology has been used, with the EcoInvent v3 AlMg3 aluminum alloy dataset as a reference. This dataset has been updated with the material composition ranges of the mentioned alloys. The balanced, maximum and minimum environmental impact values have been obtained. In general, the overall impact of the studied aluminum alloys varies from 5.98 × 10−1 pts to 1.09 pts per kg, depending on the alloy composition. In the analysis of maximum and minimum environmental impact, the alloy that has the highest uncertainty is AlSi9Cu3(Fe(Zn, with a range of ±9%. The elements that contribute the most to increase its impact are Copper and Tin. The environmental impact of a specific case, an LED luminaire housing made out of an Al Si12Cu1(Fe cast alloy, has been studied, showing the importance of considering the composition. Significant differences with the standard datasets that are currently available in EcoInvent v3 have been found.

  14. Influence of Composition on the Environmental Impact of a Cast Aluminum Alloy.

    Science.gov (United States)

    Gómez, Patricia; Elduque, Daniel; Sarasa, Judith; Pina, Carmelo; Javierre, Carlos

    2016-05-25

    The influence of alloy composition on the environmental impact of the production of six aluminum casting alloys (Al Si12Cu1(Fe), Al Si5Mg, Al Si9Cu3Zn3Fe, Al Si10Mg(Fe), Al Si9Cu3(Fe)(Zn) and Al Si9) has been analyzed. In order to perform a more precise environmental impact calculation, Life Cycle Assessment (LCA) with ReCiPe Endpoint methodology has been used, with the EcoInvent v3 AlMg3 aluminum alloy dataset as a reference. This dataset has been updated with the material composition ranges of the mentioned alloys. The balanced, maximum and minimum environmental impact values have been obtained. In general, the overall impact of the studied aluminum alloys varies from 5.98 × 10(-1) pts to 1.09 pts per kg, depending on the alloy composition. In the analysis of maximum and minimum environmental impact, the alloy that has the highest uncertainty is AlSi9Cu3(Fe)(Zn), with a range of ±9%. The elements that contribute the most to increase its impact are Copper and Tin. The environmental impact of a specific case, an LED luminaire housing made out of an Al Si12Cu1(Fe) cast alloy, has been studied, showing the importance of considering the composition. Significant differences with the standard datasets that are currently available in EcoInvent v3 have been found.

  15. Influence of yttrium oxide doping on the microstructures of alumina-niobium carbide composites

    Energy Technology Data Exchange (ETDEWEB)

    Rumbao, A.H.; Bressiani, J.C.; Bressiani, A.H.A. [IPEN - Inst. de Pesquisas Energeticas e Nucleares, Cidade Univ. - Sao Paulo, SP (Brazil)

    2003-07-01

    Ceramic cutting tools have been developed as an alternative material to cemented carbides based ones with the goal of improving cutting speeds and productivity. Among the vast variety of ceramics considered for prospective use as cutting tools materials the preference is given to the composites containing carbides as a second component, i.e., such materials as Al{sub 2}O{sub 3}-SiC, and Al{sub 2}O{sub 3}-TiC. In the present work, the influence of Y{sub 2}O{sub 3} additives on microstructure of Al{sub 2}O{sub 3}-NbC composite is studied in order to evaluate the applicability of this material for as ceramic cutting tools manufacturing. The amount of Y{sub 2}O{sub 3} additives varied in the ranged, 0-3 wt% in the Al{sub 2}O{sub 3}-NbC 20 wt% composition. Specimens were produced by consequent uniaxial and isostatic pressing followed by pressureless sintering in the flowing argon at 1750 C for 15 min in a graphite resistance furnace. The achieved densities were up to 99% TD. Microstructure evaluation in terms of grain size distribution were achieved by mean of QUANTIKOV software applied to scanning electron microscope (SEM) micrographs. Optimization of the materials composition in regard of achieving the high densities without compromising the microstructure formation are discussed. (orig.)

  16. Influence of taro (Colocasia esculenta L. Shott) growth conditions on the phenolic composition and biological properties.

    Science.gov (United States)

    Gonçalves, Rui F; Silva, Artur M S; Silva, Ana Margarida; Valentão, Patrícia; Ferreres, Federico; Gil-Izquierdo, Angel; Silva, João B; Santos, Delfim; Andrade, Paula B

    2013-12-15

    Colocasia esculenta (L.) Shott, commonly known as taro, is an essential food for millions of people. The leaves are consumed in sauces, purees, stews, and soups, being also used in wound healing treatment. Nowadays, the consumers' demand for bioactive compounds from the diet led to the development of new agricultural strategies for the production of health-promoting constituents in vegetables. In this work, two strategies (variety choice and irrigation conditions) were considered in the cultivation of C. esculenta. The effect on the phenolic composition of the leaves was evaluated. Furthermore, a correlation between the biological activity of the different varieties and their chemical composition was established. Qualitative and quantitative differences in the phenolic composition were observed between varieties; furthermore, the irrigation conditions also influenced the composition. C. esculenta varieties were able to scavenge several oxidant species and to inhibit hyaluronidase, but data suggest that metabolites other than phenolics are involved. The results show that cultivation strategies can effectively modulate the accumulation of these types of bioactive compounds. Furthermore C. esculenta wound healing potential can be attributed, at least in part, to the protection of the wound site against oxidative/nitrosative damage and prevention of hyaluronic acid degradation.

  17. The influence of self-assembly behavior of nanoparticles on the dielectric polymer composites

    Directory of Open Access Journals (Sweden)

    Xin Lu

    2013-11-01

    Full Text Available To clearify the influence of the distribution of the conductive nanoparticles on the dielectric properties of the corresponding polymer composites, the microstructure and dielectric character of the composites based on the oleic acid modified ferroferric oxide and polyvinylidene fluoride (PVDF polymer have been studied experimentally. It is found that these composites exhibit a normal percolative phase transition over the filler content from insulator to conductor, consistent with the classical percolation theory. However, when the percentage of fillers is at a certain value which is below the percolation threshold, these nanoparticles can assemble into a special porous structure in the PVDF matrix, associated with the enhancement of dielectric constant at low frequency. In addition, the controllable dispersion of conducting nanoparticles in a polymer matrix can prevent premature agglomeration at low filling fractions and avoid the appearance of anomalously early percolation. Therefore, the self-assembly behavior of nanoparticles can be beneficial to preparation of the high dielectric constant and low loss composites for the application of electric energy storage.

  18. The influence of self-assembly behavior of nanoparticles on the dielectric polymer composites

    Science.gov (United States)

    Lu, Xin; Li, Weiping; Wang, Tingting; Jiang, Long; Luo, Laihui; Hua, Dayin; Zhu, Yuejin

    2013-11-01

    To clearify the influence of the distribution of the conductive nanoparticles on the dielectric properties of the corresponding polymer composites, the microstructure and dielectric character of the composites based on the oleic acid modified ferroferric oxide and polyvinylidene fluoride (PVDF) polymer have been studied experimentally. It is found that these composites exhibit a normal percolative phase transition over the filler content from insulator to conductor, consistent with the classical percolation theory. However, when the percentage of fillers is at a certain value which is below the percolation threshold, these nanoparticles can assemble into a special porous structure in the PVDF matrix, associated with the enhancement of dielectric constant at low frequency. In addition, the controllable dispersion of conducting nanoparticles in a polymer matrix can prevent premature agglomeration at low filling fractions and avoid the appearance of anomalously early percolation. Therefore, the self-assembly behavior of nanoparticles can be beneficial to preparation of the high dielectric constant and low loss composites for the application of electric energy storage.

  19. Influence of static and cyclic climate condition on bending properties of wood plastic composites (WPC

    Directory of Open Access Journals (Sweden)

    2010-06-01

    Full Text Available Wood and natural fiber reinforced plastic composites are established for several fields like decking, transportation and automotive applications. In the last decade, extensive researches were conducted to improve the mechanical properties, such as incorporating additives like maleic anhydride grafted polypropylene (MAH-PP. The major challenge is to keep the properties in face of the environmental influence the parts are exposed to. Therefore it’s necessary to find the hardest impact factor concerning the mechanical properties. Water absorption (static and cyclic of the composites was examined at two different temperatures (23, 50°C. A correlation between duration, kind of conditioning, temperature and modification was established. The results indicate that the coupling agent MAH-PP improved significantly the water resistance of the wood plastic composites under climatic conditions and higher temperature accelerated the rate of water absorption of the composites. The decrease of mechanical properties related to cyclic conditions is partially reversible and therefore the cyclic exposition shows less effects compared to static conditions.

  20. Composition, concentration and deprivation: exploring their association with social cohesion among different ethnic groups in the UK.

    Science.gov (United States)

    Bécares, Laia; Stafford, Mai; Laurence, James; Nazroo, James

    2011-01-01

    Although studies in the US have shown an association between the ethnic residential composition of an area and reports of decreased social cohesion among its residents, this association is not clear in the UK, and particularly for ethnic minority groups. The current study analyses a merged dataset from the 2005 and 2007 Citizenship Survey to assess the evidence for an association between social cohesion and ethnic residential concentration, composition and area deprivation across different ethnic groups in the UK. Results of the multilevel regression models show that, after adjusting for area deprivation, increased levels of social cohesion are found in areas of greater ethnic residential heterogeneity. Although different patterns emerge across ethnic groups and the measure of social cohesion used, findings consistently show that it is area deprivation, and not ethnic residential heterogeneity, which erodes social cohesion in the UK.

  1. Nutrition and fatty acid composition in different botanical groups of groundnut (Arachis hypogaea. L in ICRISAT mini core collection

    Directory of Open Access Journals (Sweden)

    Ganapati Mukri , ,Shridevi Jakkeral and H.L Nadaf

    2014-09-01

    Full Text Available Breeding for enhanced nutritional quality is need of the hour. India not only needs increased quantity of food to feed the growing population but also quality food to mitigate hidden hunger. Oil is the major energy source of the Indian diet. Chemical composition of oil decides its edible nature. Even in edible oil fatty acid composition in general and ratio of oleic acid to linoleic acid of the oil plays major role in deciding its quality. In India, availability of breeding line to improve groundnut oil quality is limited. Screening of different botanical group may give some idea about choice of material for further crop improvement program. In present study botanical group hypogaea, found to have higher amount of oleic acid and fastigiata group recorded high protein and oil content. Growing season also matters in the expression of different fatty acid. Rainy season is found to have better for the better expression of all studied traits.

  2. Comparing molecular composition of dissolved organic matter in soil and stream water: Influence of land use and chemical characteristics.

    Science.gov (United States)

    Seifert, Anne-Gret; Roth, Vanessa-Nina; Dittmar, Thorsten; Gleixner, Gerd; Breuer, Lutz; Houska, Tobias; Marxsen, Jürgen

    2016-11-15

    Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS) was used to examine the molecular composition of dissolved organic matter (DOM) from soils under different land use regimes and how the DOM composition in the catchment is reflected in adjacent streams. The study was carried out in a small area of the Schwingbach catchment, an anthropogenic-influenced landscape in central Germany. We investigated 30 different soil water samples from 4 sites and different depths (managed meadow (0-5cm, 40-50cm), deciduous forest (0-5cm), mixed-coniferous forest (0-5cm) and agricultural land (0-5cm, 40-50cm)) and 8 stream samples. 6194 molecular formulae and their magnitude-weighted parameters ((O/C)w, (H/C)w, (N/C)w, (AI-mod)w, (DBE/C)w, (DBE/O)w, (DBE-O)w, (C#)w, (MW)w) were used to describe the molecular composition of the samples. The samples can be roughly divided in three groups. Group 1 contains samples from managed meadow 40-50cm and stream water, which are characterized by high saturation compared to samples from group 2 including agricultural samples and samples from the surface meadow (0-5cm), which held more nitrogen containing and aromatic compounds. Samples from both forested sites (group 3) are characterized by higher molecular weight and O/C ratio. Environmental parameters vary between sites and among these parameters pH and nitrate significantly affect chemical composition of DOM. Results indicate that most DOM in streams is of terrestrial origin. However, 120 molecular formulae were detected only in streams and not in any of the soil samples. These compounds share molecular formulae with peptides, unsaturated aliphatics and saturated FA-CHO/FA-CHOX. Compounds only found in soil samples are much more aromatic, have more double bonds and a much lower H/C ratio but higher oxygen content, which indicates the availability of fresh plant material and less microbial processed material compared to stream samples. Copyright

  3. Grape cluster microclimate influences the aroma composition of Sauvignon blanc wine.

    Science.gov (United States)

    Martin, Damian; Grose, Claire; Fedrizzi, Bruno; Stuart, Lily; Albright, Abby; McLachlan, Andrew

    2016-11-01

    New Zealand Sauvignon blanc (SB) wines are characterised by a distinctive combination of tropical-fruity and green-herbaceous aromatic compounds. The influence of sunlight exposure of grape clusters on juice and wine composition was investigated, with the aim of manipulating aromatic compounds in SB wine. In the absence of basal leaf removal SB clusters naturally exposed to sunlight were riper than shaded clusters, evidenced by higher total soluble solids (TSS) and proline, and lower malic acid, 3-isobutyl-2-methoxypyrazine (IBMP) and arginine. Volatile thiols in wines did not differ between shaded and exposed clusters. At equivalent TSS, cluster exposure had little or no effect on malic acid concentration. Conversely, wine from shaded clusters had almost double the IBMP concentration of wine from exposed clusters at equivalent TSS. The effects on SB juice and wine composition of natural variations in cluster microclimate are not comparable with the effects of cluster exposure created through leaf removal.

  4. Influence of emulsion composition and spray-drying conditions on microencapsulation of tilapia oil.

    Science.gov (United States)

    Huang, Hui; Hao, Shuxian; Li, Laihao; Yang, Xianqing; Cen, Jianwei; Lin, Wanling; Wei, Ya

    2014-09-01

    The influence of processing conditions on the microencapsulation of tilapia oil by spray drying was studied. Trehalose, gelatin, sucrose and xanthan were used as emulsion composition. The experimental parameters of spray drying such as inlet air temperature, solid content, drying air flow rate and atomizing pressure were optimized using a central composite design. Encapsulation efficiency and lipid oxidation were determined. Bulk density, powder morphology and particle size were also analyzed. Trehalose improved the glass transition temperature of wall material significantly and prevented the oxidation of the fish oil. Encapsulation efficiency reached a maximum of 90 % under optimum conditions with an inlet air temperature of 121 °C, a drying air flow rate of 0.65 m(3)/min and a spray pressure of 100 kPa.

  5. Influence of compliance of the substrate materials on polymerization contraction stress in thin resin composite layers.

    Science.gov (United States)

    Alster, D; Venhoven, B A; Feilzer, A J; Davidson, C L

    1997-02-01

    The present study determined in a laboratory set-up the influence of compliance of the substrate material on polymerisation contraction stress for various thicknesses of bonded dental resin composite films. When the compliance of the tensilometer set-up was increased from 0.029 micron MPa-1 to 0.150 micron MPa-1, the contraction stress in films with a thickness of 100 microns and a diameter of 5.35 mm decreased from 22 to 7 MPa. For the 700 microns samples the stress decreased from 12 to 11 MPa. It was concluded that if compliance from the substrate materials is possible, a thinner resin composite film may effect a more reliable bond.

  6. Influence of pressure and temperature of deformation on phase composition of yttrium ceramics

    Science.gov (United States)

    Shishkova, N. V.; Malyshev, E. N.; Shepel, V. M.; Mikheenko, P. N.

    1994-07-01

    The influence of main flatting process parameters: pressure (P) and temperature (T), when obtaining conductors, on phase composition and critical properties of YBCO system ceramics placed into Al-bronze air-tight shell has been studied. It has been found that alongside with large decrease, due to plastic deformation, of the volume of superconducting (SC) phase there exist regions of the optimal combination of pressure and temperature where volume of SC phases can be ˜60...70% conserved as comparee to initial composition. The subsequent sintering of the deformed powder at 1250 K in the air-shell resulted in ˜90% restoring of the SC phase content. Zero resistance for different samples has been observed in the 80...86 K interval. Deformation scheme and power-temperature conditions as well as the material of hermetic shell used have shown the work to be perspective one in view of substitution of expensive silver for the Al-bronze.

  7. Influence of emulsifying component composition on creams formulated with fractionated milkfat.

    Science.gov (United States)

    Scott, Lisa L; Duncan, Susan E; Sumner, Susan S; Waterman, Kim M; Kaylegian, Kerry E

    2003-09-24

    Dairy systems formulated with fractionated milkfat and milk-derived components have compositional differences that may affect functionality and nutritional aspects as compared to natural dairy products. The composition of 20% milkfat creams formulated with emulsifying components (skim milk, sweet buttermilk, and butter-derived aqueous phase) and low- or medium-melt fractionated butteroil was compared with natural cream. Cream separation temperatures (49 and 55 degrees C) and processing conditions (commercial and pilot plant) in obtaining emulsifying components were examined for effect on content of surface active agents. Individual fatty acids, lipids, cholesterol, phospholipids, protein levels, and types varied with components. Separation temperature influenced the cholesterol level in the aqueous phase. A commercially produced aqueous phase contained less total lipid, protein, cholesterol, and phospholipid than aqueous phase obtained in the pilot plant. Milkfat globule membrane concentration of emulsifying components affected phospholipid and cholesterol content of formulated creams. Butteroil type affected cholesterol levels and cream formulations.

  8. Influence of the alumina microstructure and composition in thermoluminescence for using in dosimetry

    CERN Document Server

    Silva, M R

    2001-01-01

    Among its various applications alumina may be used in thermoluminescent dosimeters (TLD) to radiations. The TLD are commonly used to determine the absorbed doses of radiation received in many application fields as nuclear installations, radiodiagnostic and radiotherapy in medicine. In this work it was developed a study of the influence of the microstructure, grain size and composition on the thermoluminescent properties in alumina (pure and carbon doped). The alumina and carbon powders used as starting materials were characterized by x-ray diffraction (XRD), chemical analysis, particle size distribution and surface area were determined by and BET analysis, respectively. The Al sub 2 O sub 3 samples were sintered at 1650 deg C in air for one, three, five, seven and ten hours. The carbon doped samples were sintered using the same temperature for one hour, in a graphite resistance furnace in argon. Sintered materials were further characterised for phase composition and microstructure by XRD and scanning electron...

  9. Influence of Charge Shape and Orientation on the Response of Steel-Concrete Composite Panels

    Directory of Open Access Journals (Sweden)

    Abraham Christian

    2016-09-01

    Full Text Available Blast design codes usually generalize the shape of the charge as spherical or hemispherical. However, it was found that the blast overpressure of cylindrical charges differ greatly when compared with relevant analytical results generated with the charges assumed to be spherical. The objective is to use fully coupled 3D multi-material arbitrary Lagrangian Eulerian (MMALE modelling technique in LS Dyna software to simulate the cylindrical charge blast loading. Comparison of spherical and cylindrical charge blast simulation was carried out to show the influence on peak overpressure and total impulse. Two steel-concrete composite specimens were subjected to blast testing under cylinder charges for benchmarking against numerical results. It was found that top detonated, vertical cylinder charge could give much higher blast loading compared to horizontal cylinder charge. The MMALE simulation could generate the pressure loading of various charge shape and orientation to be used for predicting the response of the composite panel.

  10. Experimental assessment of environmental influences on the stable isotopic composition of Daphnia pulicaria and their ephippia

    Directory of Open Access Journals (Sweden)

    J. Schilder

    2015-02-01

    δ15N values of ephippia and Daphnia between the 12 °C and 20 °C treatments, but the δ18O values of Daphnia and ephippia were on average 1.2‰ lower at 20 °C compared with 12 °C. We conclude that the stable isotopic composition of Daphnia ephippia provides information on that of the parent Daphnia and of the food and water they were exposed to, with small offsets between Daphnia and ephippia relative to variations in Daphnia stable isotopic composition reported from downcore studies. However, our experiments also indicate that temperature may have a minor influence on the δ13C, δ15N and δ18O values of Daphnia body tissue and ephippia. This aspect deserves attention in further controlled experiments.

  11. Influence of composition and heat treatments on corrosion resistance of Fe-Co-BSi amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Angelini, E.; Antonione, C.; Baricco, M.; Rosalbino, F.; Zucchi, F. (Ist. Elettrotecnico Nazionale Galileo Ferraris, Turin (Italy) Turin Univ. (Italy) Politecnico di Torino (Italy))

    This paper studies the influence of composition and heat treatments on the corrosion resistance, in a solution of Na/sub 2/SO/sub 4/ 0.05M + H/sub 2/SO/sub 4/ 0.05M, at 1.5 pH, of a series of iron base amorphous alloys with increasing cobalt content, i.e., Fe/sub 80-x/Co/sub x/B/sub 10/Si/sub 10/ with x=0, 30, and 80. The treatments were carried out in an argon atmosphere over increasing time durations: 30, 60, 120, and 240 minutes, and increasing temperatures: 350, 400, 450 and 500 degrees C respectively. It was possible to observe that, independent of heat treatment, the corrosion resistance increased with increasing cobalt concentration. In comparing samples having the same chemical composition, it was noted that their electrochemical behaviour worsened with increasing temperature and time.

  12. High-performance composite membrane with enriched CO2-philic groups and improved adhesion at the interface.

    Science.gov (United States)

    Li, Yifan; Wang, Shaofei; Wu, Hong; Guo, Ruili; Liu, Ye; Jiang, Zhongyi; Tian, Zhizhang; Zhang, Peng; Cao, Xingzhong; Wang, Baoyi

    2014-05-14

    A novel strategy to design a high-performance composite membrane for CO2 capture via coating a thin layer of water-swellable polymers (WSPs) onto a porous support with enriched CO2-philic groups is demonstrated in this study. First, by employing a versatile platform technique combining non-solvent-induced phase separation and surface segregation, porous support membranes with abundant CO2-philic ethylene oxide (EO) groups at the surface are successfully prepared. Second, a thin selective layer composed of Pebax MH 1657 is deposited onto the support membranes via dip coating. Because of the water-swellable characteristic of Pebax and the enriched EO groups at the interface, the composite membranes exhibit high CO2 permeance above 1000 GPU with CO2/N2 selectivity above 40 at a humidified state (25 °C and 3 bar). By tuning the content of the PEO segment at the interface, the composite membranes can show either high CO2 permeance up to 2420 GPU with moderate selectivity of 46.0 or high selectivity up to 109.6 with fairly good CO2 permeance of 1275 GPU. Moreover, enrichment of the PEO segment at the interface significantly improves interfacial adhesion, as revealed by the T-peel test and positron annihilation spectroscopy measurement. In this way, the feasibility of designing WSP-based composite membranes by enriching CO2-philic groups at the interface is validated. We hope our findings may pave a generic way to fabricate high-performance composite membranes for CO2 capture using cost-effective materials and facile methods.

  13. Influence of immediate dentin sealing techniques on cuspal deflection and fracture resistance of teeth restored with composite resin inlays.

    Science.gov (United States)

    Oliveira, L; Mota, E G; Borges, G A; Burnett, L H; Spohr, A M

    2014-01-01

    SUMMARY This research evaluated the influence of immediate dentin sealing (IDS) techniques on cuspal deflection and fracture resistance of teeth restored with composite resin inlays. Forty-eight maxillary premolars were divided into four groups: G1, sound teeth (control); G2, without IDS; G3, IDS with Clearfil SE Bond (CSE); and G4, IDS with CSE and Protect Liner F. The teeth from groups 2, 3, and 4 received mesio-distal-occlusal preparations. The impressions were made with vinyl polysiloxane, followed by provisional restoration and storage in water for seven days. The impressions were poured using type IV die stone, and inlays with Filtek Z250 composite resin were built over each cast. The inlays were luted with Panavia F. After storage in water for 72 hours, a 200-N load was applied on the occlusal surface using a metal sphere connected to a universal testing machine, and the cuspal deflection was measured with a micrometer. The specimens were then submitted to an axial load until failure. The following mean cuspal deflection (μm) and mean fracture resistance (N) followed by the same lowercase letter represent no statistical difference by analysis of variance and Tukey (p<0.05): cuspal deflection: G1, 3.1 ± 1.5(a); G2, 10.3 ± 4.6(b); G3, 5.5 ± 1.8(ac); and G4, 7.7 ± 5.1(bc); fracture resistance: G1, 1974 ± 708(a); G2, 1162 ± 474(b); G3, 700 ± 280(b); and G4, 810 ± 343(b). IDS with CSE allowed cuspal deflection comparable with that associated with sound teeth. The application of Protect Liner F did not contribute to a decrease in cuspal deflection. The IDS techniques did not influence the fracture resistance of teeth.

  14. Composite resin color stability: influence of light sources and immersion media

    Directory of Open Access Journals (Sweden)

    Patricia Aleixo dos Santos Domingos

    2011-06-01

    Full Text Available OBJECTIVE: This study evaluated the influence of light sources and immersion media on the color stability of a nanofilled composite resin. MATERIAL AND METHODS: Conventional halogen, high-power-density halogen and high-power-density light-emitting diode (LED units were used. There were 4 immersion media: coffee, tea, Coke® and artificial saliva. A total of 180 specimens (10 mm x 2 mm were prepared, immersed in artificial saliva for 24 h at 37±1ºC, and had their initial color measured with a spectrophotometer according to the CIELab system. Then, the specimens were immersed in the 4 media during 60 days. Data from the color change and luminosity were collected and subjected to statistical analysis by the Kruskall-Wallis test (p<0.05. For immersion time, the data were subjected to two-way ANOVA test and Fisher's test (p<0.05. RESULTS: High-power-density LED (ΔE=1.91 promoted similar color stability of the composite resin to that of the tested halogen curing units (Jet Lite 4000 plus - ΔE=2.05; XL 3000 - ΔE=2.28. Coffee (ΔE=8.40; ΔL=-5.21 showed the highest influence on color stability of the studied composite resin. CONCLUSION: There was no significant difference in color stability regardless of the light sources, and coffee was the immersion medium that promoted the highest color changes on the tested composite resin.

  15. Influence of matrix systems on proximal contact tightness of 2- and 3-surface posterior composite restorations in vivo

    NARCIS (Netherlands)

    Wirsching, E.; Loomans, B.A.C.; Klaiber, B.; Dorfer, C.E.

    2011-01-01

    OBJECTIVES: To investigate the influence of cavity preparation (MO/DO/MOD) and type of matrix system on proximal contact tightness of direct posterior composite restorations. MATERIALS AND METHODS: 85 patients in need of a two- or three surface Class II direct composite restoration were randomly div

  16. Influence of the physical structure of flax fibres on the mechanical properties of flax fibre reinforced polypropylene composites

    NARCIS (Netherlands)

    Oever, van den M.J.A.; Bos, H.L.; Kemenade, van M.J.J.M.

    2000-01-01

    This study investigates the influence of the physical structure of flax fibres on the mechanical properties of polypropylene (PP) composites. Due to their composite-like structure, flax fibres have relatively weak lateral bonds which are in particular present in flax fibres that are often used in na

  17. The influence of emotional facial expressions on gaze-following in grouped and solitary pedestrians.

    Science.gov (United States)

    Gallup, Andrew C; Chong, Andrew; Kacelnik, Alex; Krebs, John R; Couzin, Iain D

    2014-07-23

    The mechanisms contributing to collective attention in humans remain unclear. Research indicates that pedestrians utilise the gaze direction of others nearby to acquire environmentally relevant information, but it is not known which, if any, additional social cues influence this transmission. Extending upon previous field studies, we investigated whether gaze cues paired with emotional facial expressions (neutral, happy, suspicious and fearsome) of an oncoming walking confederate modulate gaze-following by pedestrians moving in a natural corridor. We found that pedestrians walking alone were not sensitive to this manipulation, while individuals traveling together in groups did reliably alter their response in relation to emotional cues. In particular, members of a collective were more likely to follow gaze cues indicative of a potential threat (i.e., suspicious or fearful facial expression). This modulation of visual attention dependent on whether pedestrians are in social aggregates may be important to drive adaptive exploitation of social information, and particularly emotional stimuli within natural contexts.

  18. Influence of alkyl group of imidazolinyl-quaternary-ammonium-salt on corrosion inhibition efficiency

    Institute of Scientific and Technical Information of China (English)

    SHI Shun-cun; WANG Xue-ye; YI Ping-gui; CAO Chen-zhong; DENG Tong-tong; SU Jie-shu

    2006-01-01

    The action between imidazolinyl-quaternary-ammonium-salt(IQAS) molecule and Fe atom was studied,and the influence of the alkyl group connected with N atom of imidazoline ring on corrosion inhibition efficiency was explored. Quantum chemical methods, HF/6- 31 G and HF/Lan L2 dz, were applied successively to calculate the parameters such as front molecular orbit energy of IQAS Ⅰ-Ⅳ and chemical adsorption for IQAS Ⅰ-Ⅳ and Fe atom.The corrosion inhibition efficiency was measured with the weight loss method of carbon steel samples in acidic solution and oil field sewage. Based on the theoretical analyses and experimental results, it is concluded that N-Fe coordination bond is formed between IQAS molecule and Fe atom, corrosion inhibition efficiency is decreased in the following order(from large to small): IQAS Ⅳ, IQAS Ⅲ, IQAS Ⅱ , IQAS Ⅰ.

  19. Analysis of changes in selected parameters of calcium and magnesium metabolism in response to diet composition and B-group vitamin supplementation in rat

    Directory of Open Access Journals (Sweden)

    Joanna Sadowska

    2010-09-01

    Full Text Available Background. The aim of the study was to investigate the effects of a diet modification and supplementation with B-group vitamins, on selected characteristics of calcium and magnesium management in rats. Material and methods. The experiment was carried out on 60 rats aged 5 months. Animals were fed two different diets. Groups I and II received clean tap water to drink, while group III had water solution of group-B vitamins. Results. Analysis of blood plasma calcium and magnesium concentrations in the studied animals did not reveal a significant effect of the analysed factors on blood plasma calcium concentration in examined rats. An increase of the plasma level of magnesium was observed with a change in the diet composition. The supplementation reduced magnesium level to those observed in animals fed a basic feed. Diet modification and supplementation exerted the influence on whole blood calcium and magnesium levels. A change in the composition of the diet and its supplementation results also in an increase in bone calcium content in males, and in an increase in bone magnesium content in females. Conclusions. Lack of changes in blood plasma calcium levels in the studied animals implies the preservation of the homeostatic mechanisms that regulate its concentration, whereas the observed significant changes in the concentration of magnesium, point to a significant effect of this factor on its metabolism. Changes in hematocrit indicator, whole blood concentrations of calcium and magnesium and the absence of changes in concentrations of these elements in blood plasma of supplemented animals may indicate that the elements move to erythrocytes, which may imply a distortion of cellular membrane and an increase in its permeability. Composition of the diet and its supplementation modified also bone calcium and magnesium concentrations in the studied rats.

  20. Influence of stuttering variation on talker group classification in preschool children: Preliminary findings

    Science.gov (United States)

    Johnson, Kia N.; Karrass, Jan; Conture, Edward G.; Walden, Tedra

    2010-01-01

    The purpose of this study was to investigate whether variations in disfluencies of young children who do (CWS) and do not stutter (CWNS) significantly change their talker group classification or diagnosis from stutterer to nonstutterer, and vice versa. Participants consisted of 17 3- to 5-year-old CWS and 9 3- to 5-year-old CWNS, with no statistically significant between-group difference in chronological age (CWS: M = 45.53 months, SD = 8.32; CWNS: M = 47.67 months, SD = 6.69). All participants had speech, language, and hearing development within normal limits, with the exception of stuttering for CWS. Both talker groups participated in a series of speaking samples that varied by: (a) conversational partner [parent and clinician], (b) location [home and clinic], and (c) context [conversation and narrative]. The primary dependent measures for this study were the number of stuttering-like disfluencies (SLD) per total number of spoken words [%SLD] and the ratio of SLD to total disfluencies (TD) [SLD/TD]. Results indicated that significant variability of stuttering did not exist as a result of conversational partner or location. Changes in context, however, did impact the CWS, who demonstrated higher SLD/TD in the conversation sample versus a narrative sample. Consistent with hypotheses, CWS and CWNS were accurately identified as stutterers and nonstutterers, respectively, regardless of changes to conversational partner, location or context for the overall participant sample. Present findings were taken to suggest that during assessment, variations in stuttering frequency resulting from changes in conversational partner, location or context do not significantly influence the diagnosis of stuttering, especially for children not on the talker group classification borderline between CWS and CWNS. PMID:19167719

  1. The influence of maternal Lewis, Secretor and ABO(H) blood groups on fetal growth restriction.

    Science.gov (United States)

    Clark, P; Greer, I A

    2011-12-01

    Fetal growth restriction (FGR) is associated with thrombosis of the placenta and an increased risk of subsequent vascular disease in the mother and fetus. The products of interactions between ABO(H), Lewis and Secretor genes are also associated with thrombosis and vascular disease risk. A prospective case-control study of mothers with a severe FGR pregnancy (cases, n = 128; controls, n = 288) was performed to determine whether FGR is associated with particular maternal blood groups. No association with ABO(H) status was observed, but FGR was more common in maternal secretors (odds ratio [OR] 1.70, 95% confidence interval [CI] 1.08-2.69) and consequently in those mothers expressing Le(b) on their red cells (OR 1.80, 95% CI 1.15-2.83), with a reduced risk in non-secretors and those expressing Le(a). Given the association between blood groups and both activated protein C resistance (APCR) and von Willebrand factor (VWF) levels, post hoc pilot studies on first-trimester APCR and VWF antigen levels and blood group genotypes were performed. No relationship with Lewis or Secretor was observed. Despite this, lower first-trimester VWF levels were observed in pregnancies subsequently complicated by FGR.  This is the first study reporting a relationship between maternal Secretor/Lewis status and FGR. A link between blood groups and FGR is plausible, as both are associated with cardiovascular disease. We observed no relationship between Lewis/Secretor status and VWF or APCR, but this should be confirmed in a larger study. Thus, the mechanism whereby Secretor and/or Lewis influences FGR is unknown. © 2011 International Society on Thrombosis and Haemostasis.

  2. Sediment composition influences spatial variation in the abundance of human pathogen indicator bacteria within an estuarine environment.

    Directory of Open Access Journals (Sweden)

    Tracy L Perkins

    Full Text Available Faecal contamination of estuarine and coastal waters can pose a risk to human health, particularly in areas used for shellfish production or recreation. Routine microbiological water quality testing highlights areas of faecal indicator bacteria (FIB contamination within the water column, but fails to consider the abundance of FIB in sediments, which under certain hydrodynamic conditions can become resuspended. Sediments can enhance the survival of FIB in estuarine environments, but the influence of sediment composition on the ecology and abundance of FIB is poorly understood. To determine the relationship between sediment composition (grain size and organic matter and the abundance of pathogen indicator bacteria (PIB, sediments were collected from four transverse transects of the Conwy estuary, UK. The abundance of culturable Escherichia coli, total coliforms, enterococci, Campylobacter, Salmonella and Vibrio spp. in sediments was determined in relation to sediment grain size, organic matter content, salinity, depth and temperature. Sediments that contained higher proportions of silt and/or clay and associated organic matter content showed significant positive correlations with the abundance of PIB. Furthermore, the abundance of each bacterial group was positively correlated with the presence of all other groups enumerated. Campylobacter spp. were not isolated from estuarine sediments. Comparisons of the number of culturable E. coli, total coliforms and Vibrio spp. in sediments and the water column revealed that their abundance was 281, 433 and 58-fold greater in sediments (colony forming units (CFU/100g when compared with the water column (CFU/100ml, respectively. These data provide important insights into sediment compositions that promote the abundance of PIB in estuarine environments, with important implications for the modelling and prediction of public health risk based on sediment resuspension and transport.

  3. Environmental influences on African migration to Canada: focus group findings from Ottawa-Gatineau.

    Science.gov (United States)

    Veronis, Luisa; McLeman, Robert

    2014-01-01

    There is limited empirical evidence of how environmental conditions in the Global South may influence long-distance international migration to the Global North. This research note reports findings from seven focus groups held in Ottawa-Gatineau, Canada, with recent migrants from the Horn of Africa and francophone sub-Saharan Africa, where the role of environment in migration decision-making was discussed. Participants stated that those most affected by environmental challenges in their home countries lack the financial wherewithal to migrate to Canada. Participants also suggested that internal rural-urban migration patterns generated by environmental challenges in their home countries underlay socioeconomic factors that contributed to their own migration. In other words, environment is a second- or third-order contributor in a complex chain of interactions in the migrant source country that may lead to long-distance international migration by skilled and educated urbanites. These findings have informed the scope and detail of a larger, ongoing empirical study of environmental influences on immigration to Canada.

  4. Influence of sample composition and processing parameters on the UV cure of clear coatings

    Science.gov (United States)

    Ruiz, C. S. B.; Machado, L. D. B.; Volponi, J. E.; Pino, E. S.

    2003-08-01

    Photocurable systems consist of functional macromolecules, which undergo polymerization and a photoinduced crosslinking reaction under UV irradiation. Radiation-curable coatings have gained importance because they are environmentally friendly and save more energy than conventional heat-curable processes. The performance of UV-curable coatings depends on their formulation and cure quality. The quality of UV radiation cure depends on lamp characteristics, photoinitiator (PI) content, film thickness, curing environment, substrate and temperature. The aim of this study was to evaluate the influence of coating thickness and UV radiation dose, as well as coating characteristics such as PI content and stabilizer additive composition, on the curing process.

  5. Influence of meal composition on postprandial peripheral plasma concentrations of vasoactive peptides in man

    DEFF Research Database (Denmark)

    Pedersen-Bjergaard, U; Høst, U; Kelbaek, H

    1996-01-01

    In a randomized cross-over study healthy non-obese male human subjects received standardized isocaloric, isovolumetric meals consisting of either carbohydrate, protein or fat and a non-caloric control meal consisting of an equal volume of water. Peripheral venous plasma concentrations of calcitonin...... that the postprandial peripheral plasma concentrations of CGRP, VIP and PYY are dependent on the caloric meal composition. The VIP, but not the CGRP and PYY concentrations seem to be influenced by gastric distension. The physiological significance of the postprandial alterations in peripheral concentrations...

  6. The influence of vegetation fires on the chemical composition of the atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Helas, H.; Pienaar, J.J. [Max Planck Institute of Chemistry, Mainz (Germany). Biogeochemistry Dept.

    1996-03-01

    The authors discuss the influence of vegetation fires on the chemical composition of the atmosphere and compare the contribution of these fires to atmospheric pollution with other natural and anthropogenic sources. In the case of South Africa, the comparison shows that for CO{sub 2}, NO{sub x} and SO{sub 2}, industrial coal use is the largest contributor whereas for CO and CH{sub 4}, vegetation fires contribute the most. As a source of atmospheric NO{sub x} motor vehicles are more important than emissions from veld fires.

  7. Influence of Composition of Sm2O3-Containing Rare Earth Glass on Its Absorption Spectrum

    Institute of Scientific and Technical Information of China (English)

    Zhang Qitu; Wang Tingwei; Meng Xianfeng; Shan Xiaobing; Xu Zhongzi

    2005-01-01

    Borosilicate glass with high rare earth content was fabricated by traditional method. The influence of glass compositions and rare earth content on absorption spectra was examined and discussed. With increasing Sm2O3 content, the intensity of characteristic absorption peak is increased and the absorption peak is broadened. With increasing of the ratios of SiO2/B2O3 and Al2O3/SiO2, the broadening degree of absorption peak is increased. The experimental results provide basis for making special optical glasses which have the characteristics of high absorption for special wavelength laser and high transparence for visible light.

  8. The Influence of Collaborative Group Work on Students' Development of Critical Thinking: The Teacher's Role in Facilitating Group Discussions

    Science.gov (United States)

    Fung, Dennis Chun-Lok; To, Helen; Leung, Kit

    2016-01-01

    The objective of this study was to determine whether the incorporation of group work in a teaching intervention can effectively foster students' critical thinking skills. Building upon Kuhn's critical thinking model, the research involved comparison of pretest and post-test results for 140 secondary four (10th grade) students in Hong Kong on two…

  9. Influence of Stellar Flares on the Chemical Composition of Exoplanets and Spectra

    Science.gov (United States)

    Venot, Olivia; Rocchetto, Marco; Carl, Shaun; Roshni Hashim, Aysha; Decin, Leen

    2016-10-01

    More than three thousand exoplanets have been detected so far, and more and more spectroscopic observations of exoplanets are performed. Future instruments (James Webb Space Telescope (JWST), E-ELT, PLATO, Ariel, etc.,) are eagerly awaited, as they will be able to provide spectroscopic data with greater accuracy and sensitivity than what is currently available. This will allow more accurate conclusions to be drawn regarding the chemistry and dynamics of exoplanetary atmospheres, provided that the observational data are carefully processed. One important aspect to consider is temporal stellar atmospheric disturbances that can influence the planetary composition, and hence spectra, and potentially can lead to incorrect assumptions about the steady-state atmospheric composition of the planet. In this paper, we focus on perturbations coming from the host star in the form of flare events that significantly increase photon flux impingement on the exoplanets atmosphere. In some cases, particularly for M stars, this sudden increase may last for several hours. We aim to discover to what extent a stellar flare is able to modify the chemical composition of the planetary atmosphere and, therefore, influence the resulting spectra. We use a one-dimensional thermo-photochemical model to study the neutral atmospheric composition of two hypothetical planets located around the star AD Leo. We place the two planets at different distances from the star, which results in effective atmospheric temperatures of 412 and 1303 K. AD Leo is an active star that has already been observed during a flare. Therefore, we use the spectroscopic data from this flare event to simulate the evolution of the chemical composition of the atmospheres of the two hypothetical planets. We compute synthetic spectra to evaluate the implications for observations. The increase in the incoming photon flux affects the chemical abundances of some important species (such as H and NH3), down to altitudes associated with

  10. Quantitative Approach to Collaborative Learning: Performance Prediction, Individual Assessment, and Group Composition

    Science.gov (United States)

    Cen, Ling; Ruta, Dymitr; Powell, Leigh; Hirsch, Benjamin; Ng, Jason

    2016-01-01

    The benefits of collaborative learning, although widely reported, lack the quantitative rigor and detailed insight into the dynamics of interactions within the group, while individual contributions and their impacts on group members and their collaborative work remain hidden behind joint group assessment. To bridge this gap we intend to address…

  11. Quantitative Approach to Collaborative Learning: Performance Prediction, Individual Assessment, and Group Composition

    Science.gov (United States)

    Cen, Ling; Ruta, Dymitr; Powell, Leigh; Hirsch, Benjamin; Ng, Jason

    2016-01-01

    The benefits of collaborative learning, although widely reported, lack the quantitative rigor and detailed insight into the dynamics of interactions within the group, while individual contributions and their impacts on group members and their collaborative work remain hidden behind joint group assessment. To bridge this gap we intend to address…

  12. Experimental and Kinetic Investigation of the Influence of OH Groups on NOX Formation

    KAUST Repository

    Bohon, Myles

    2016-05-04

    This work investigates the influence of one or more OH groups present on the fuel molecule and the resultant formation of NOX emissions. Combustion of oxygenated fuels has been increasing globally and such fuels offer significant potential in the reduction of pollutant emissions. One such emission class is the oxides of nitrogen, which typically form through a combination of two regimes: the thermal and non-thermal mechanisms. While thermal NO formation can be reduced by lowering the combustion temperature, non-thermal NO formation is coupled to the fuel chemistry. An experimental and computational investigation of NOX formation in three different burner configurations and under a range of equivalence ratios and temperature regimes explored the differences in NO formation. Measurements of temperature profiles and in-flame species concentrations, utilizing both probed and non-intrusive laser based techniques, allowed for the investigation of NO formation through non-thermal pathways and the differences that exist between fuels with varying numbers of OH groups. The first burner configuration was composed of a high swirl liquid spray burner with insulted combustion chamber walls designed specifically for the combustion of low energy density fuels. In this system the combustion of alcohols and glycerol (the largest by-product of biodiesel production), along with other fuels with multiple hydroxyl groups, was studied. Measurements of the mean flame temperature and exhaust gas measurements of NOX showed significant reductions in non-thermal NO concentrations with increasing numbers of OH groups. An accompanying modeling study and detailed reaction path analysis showed that fuel decomposition pathways through formaldehyde were shown a preference due to the presence of the OH groups which resulted in reduced contributions to the hydrocarbon radical pools subsequent reductions to the Prompt NO mechanism. Two burner configurations with reduced dimensionality facilitated

  13. Temporary versus permanent group membership: how the future prospects of newcomers affect newcomer acceptance and newcomer influence.

    Science.gov (United States)

    Rink, Floor A; Ellemers, Naomi

    2009-06-01

    Three studies examine how the future prospects of new group members affect newcomer acceptance and newcomer influence. In Study 1, participants anticipate accepting temporary newcomers less easily than permanent newcomers because they expect temporary newcomers to differ from the group. In Study 2, the effects of newcomer entry in three-person groups are examined. Results show that groups perceived temporary newcomers as more involved in a judgmental decision-making process than permanent newcomers. In Study 3, a hidden profile task confirms that temporary newcomers indeed shared more unique knowledge during discussions than permanent newcomers and that this enhanced the groups' decision quality. However, compared to permanent newcomers, temporary newcomers caused teams to experience more conflict and less group identification, illustrating the tension between innovative group performance and group cohesion. The results are discussed in light of the social identity perspective and research on minority influence.

  14. Spectral Analysis by XANES Reveals that GPNMB Influences the Chemical Composition of Intact Melanosomes

    Energy Technology Data Exchange (ETDEWEB)

    T Haraszti; C Trantow; A Hedberg-Buenz; M Grunze; M Anderson

    2011-12-31

    GPNMB is a unique melanosomal protein. Unlike many melanosomal proteins, GPNMB has not been associated with any forms of albinism, and it is unclear whether GPNMB has any direct influence on melanosomes. Here, melanosomes from congenic strains of C57BL/6J mice mutant for Gpnmb are compared to strain-matched controls using standard transmission electron microscopy and synchrotron-based X-ray absorption near-edge structure analysis (XANES). Whereas electron microscopy did not detect any ultrastructural changes in melanosomes lacking functional GPNMB, XANES uncovered multiple spectral phenotypes. These results directly demonstrate that GPNMB influences the chemical composition of melanosomes and more broadly illustrate the potential for using genetic approaches in combination with nano-imaging technologies to study organelle biology.

  15. The influence of imitated microgravity on the amyloplast structure, the composition and characteristics of potato minituber

    Science.gov (United States)

    Nedukha, O. M.; Kordyum, Ye. L.; Schnyukova, Ye. I.

    The influence of imitated microgravity (clinorotation, 2 rev/min) of long-term duration on the structural-functional organization of Solanum tuberosum L. (cv Adreta) minituber cells is studied. An essential influence on 45-day minituber size, on the content and composition of starch, on the solubility of starch in water and on the structure of amyloplasts in the storage parenchyma of potato minitubers is detected. The appearance of a fraction of "gigantic" amyloplasts in starch-storage parenchyma is observed during horizontal clinorotation of long-term duration. The correlation between the decrease of content amylose and the inhibition of starch solubility in water is detected under long-term clinorotation. The results point to some changes of the carbohydrate metabolism of potato storage organs under the effect of microgravity imitation.

  16. Influence of Fabric Geometrical Structure on Bonding of the Fabric Reinforced Cement Composites

    Institute of Scientific and Technical Information of China (English)

    YU Qiao-zhen

    2007-01-01

    Influence of fabric geometrical parameters,including the number of filling yams per 10 cm, yarntwist and fiber type, on bonding of the fabric reinforcedcement composites is studied by fabric pull-out test andSEM microstructure analysis. The results show that thebonding strength increase with the increase of the numberof filling yams per 10 cm in the range of this study. Butthe influence of fabric count on the interfacial bonding isdual and there is a critical value. The twist of yarns hasa little effect on the bending strength and interfacialbonding behaves of nylon fabric reinforced cementcomposites. There is an optimum twist range. Withinthis range, the bonding strength increase slowly with theincrease of yarn twist. Beyond this range, it is versus.The bonding strength is strongly affected by the fabriccharacter. The bonding between the nylon fiber fabricand cement is good; that of between glass fiber fabric andcement is moderate and that of between the carbon fiberfabric and cement is poor.

  17. Influence of preconsolidation on consolidation quality after stamp forming of C/PEEK composites

    Science.gov (United States)

    Slange, T. K.; Warnet, L.; Grouve, W. J. B.; Akkerman, R.

    2016-10-01

    Stamp forming is a rapid manufacturing technology used to shape flat blanks of thermoplastic composite material into three-dimensional components. Currently, expensive autoclave and press consolidation are used to preconsolidate blanks. This study investigates the influence of preconsolidation on final consolidation quality after stamp forming and explores the potential of alternative blank manufacturing methods that could reduce part costs. Blanks were manufactured using various blank manufacturing methods and subsequently were stamp formed. The consolidation quality both before and after stamp forming was compared, where the focus was on void content as the main measure for consolidation quality. The void content was characterized through thickness and density measurements, as well as by microscopy analysis. Results indicate that preconsolidation quality does have an influence on the final consolidation quality. This is due to the severe deconsolidation and limited reconsolidation during stamp forming. Nevertheless, the potential of automated fiber placement and ultrasonic spot welding as alternative blank manufacturing methods was demonstrated.

  18. INFLUENCE OF THE COMPOSITION OF MILK POWDER ON WATER ACTIVITY APPLYING THE GAB MODEL

    Directory of Open Access Journals (Sweden)

    Julio Gil

    2016-03-01

    Full Text Available The use of sorption isotherms at 25°C, for analyze the influence of water activity (aw of the different compositions of whole milk, skim and low in lactose powder, was study. Precisely the latter incorporating previous work can extend the differential behavior of the various components. The work can establish the relationship between the moisture content of the milk powders studied, with its water activity (aw. The experimental results are evaluated with reference model GAB, noting that the layout of the isotherms and the model parameters were successfully adjusted to the values obtained. The clear influence of the presence of monosaccharides (glucose and galactose in the reduced-lactose milk, which reduce the water activity aw from greater value of 0.4 due to the higher solubility of these, is observed. The fat content in whole milk, not being adsorbent is manifested in higher values for water activity.

  19. Association between Self-Rated Health and the Ethnic Composition of the Residential Environment of Six Ethnic Groups in Amsterdam

    Directory of Open Access Journals (Sweden)

    Eleonore M. Veldhuizen

    2015-11-01

    Full Text Available Background: Studies on the association between health and neighborhood ethnic composition yielded inconsistent results, possibly due to methodological limitations. We assessed these associations at different spatial scales and for different measures of ethnic composition. Methods: We obtained health survey data of 4673 respondents of Dutch, Surinamese, Moroccan, Turkish other non-Western and other Western origin. Neighborhood ethnic composition was measured for buffers varying from 50–1000 m. Associations with self-rated health were measured using logistic multilevel regression analysis, with control for socioeconomic position at the individual and area level. Results: Overall ethnic heterogeneity was not related to health for any ethnic group. The presence of other Surinamese was associated with poor self-rated health among Surinamese respondents. The presence of Moroccans or Turks was associated with poor health among some groups. The presence of Dutch was associated with better self-rated health among Surinamese and Turks. In most cases, these associations were stronger at lower spatial scales. We found no other associations. Conclusions: In Amsterdam, self-rated health was not associated with ethnic heterogeneity in general, but may be related to the presence of specific ethnic groups. Policies regarding social and ethnic mixing should pay special attention to the co-residence of groups with problematic interrelations.

  20. The composition of coexisting jarosite-group minerals and water from the Richmond mine, Iron Mountain, California

    Science.gov (United States)

    Jamieson, H.E.; Robinson, C.; Alpers, C.N.; Nordstrom, D.K.; Poustovetov, A.; Lowers, H.A.

    2005-01-01

    Jarosite-group minerals accumulate in the form of stalactites and fine-grained mud on massive pyrite in the D drift of the Richmond mine, Iron Mountain, California. Water samples were collected by placing beakers under the dripping stalactites and by extracting pore water from the mud using a centrifuge. The water is rich in Fe3+ and SO42-, with a pH of approximately 2.1, which is significantly higher than the extremely acidic waters found elsewhere in the mine. Electron-microprobe analysis and X-ray mapping indicate that the small crystals (<10 ??m in diameter) are compositionally zoned with respect to Na and K, and include hydronium jarosite corresponding to the formula (H3O)0.6K0.3 Na0.1Fe3+3 (SO4)2(OH)6. The proton-microprobe analyses indicate that the jarosite-group minerals contain significant amounts of As, Pb and Zn, and minor levels of Bi, Rb, Sb, Se, Sn and Sr. Speciation modeling indicates that the drip waters are supersaturated with respect to jarosite-group minerals. The expected range in composition of jarosite-group solid-solution in equilibrium with the pore water extracted from the mud was found to be consistent with the observed range in composition.

  1. Influence of the nature of surface-active substances on rheology of high-filled pastelike compositions on a base on liquid diene rubber and disperse filler

    Directory of Open Access Journals (Sweden)

    Alexander B. Surovtcev

    2014-12-01

    Full Text Available Results of researches on reception of pastelike high-filled compositions and estimation of their rheological properties with use cone – plate rheometer are presented. Liquid diene rubber with end hydroxyl groups (as binding, surfaceactive substance (PEAHENS and disperse filler are entered into structure of compositions. The estimation of sedimentation firmness of compositions and their fluidity in the range of pressure of shift 1 – 30 кPа and temperatures from 30 to 50°С is executed. By results of an estimation of influence of concentration dependence of PEAHENS on a viscosity indicator it is shown that its introduction in a pastelike composition at level 0.5 mas. % is expedient. For considered in work low polar liquid diene rubber more effective decrease in viscosity of a pastelike composition provide polyoxypropylene, especially on the average an interval of pressure of shift which basically can be used in practice. Slightly concede them titanorganic derivatives of oligomer polyoxypropylene. The greatest effect of decrease in viscosity for compositions will reach at use oligomer polyoxypropylene with molecular weight 480, in this case viscosity of a composition is at level of 10 Pa ⋅ s for rather wide interval of pressure of shift.

  2. What Online Networks Offer: Online Network Compositions and Online Learning Experiences of Three Ethnic Groups

    NARCIS (Netherlands)

    Lecluijze, Susanne Elisabeth; de Haan, M.J.; Ünlüsoy, A.

    2015-01-01

    This exploratory study examines ethno-cultural diversity in youth ́s narratives regarding their online learning experiences while also investigating how these narratives can be understood from the analysis of their online network structure and composition. Based on ego-network data of 79 respondents

  3. What Online Networks Offer: Online Network Compositions and Online Learning Experiences of Three Ethnic Groups

    NARCIS (Netherlands)

    Lecluijze, Susanne Elisabeth; de Haan, M.J.; Ünlüsoy, A.

    2015-01-01

    This exploratory study examines ethno-cultural diversity in youth ́s narratives regarding their online learning experiences while also investigating how these narratives can be understood from the analysis of their online network structure and composition. Based on ego-network data of 79 respondents

  4. Bond strength between fiber posts and composite resin core: influence of temperature on silane coupling agents.

    Science.gov (United States)

    Novais, Veridiana Resende; Simamotos Júnior, Paulo Cézar; Rontani, Regina Maria Puppin; Correr-Sobrinho, Lourenço; Soares, Carlos José

    2012-01-01

    This study evaluated the effect of air drying temperature and different silane coupling agents on the bond strength between glass fiber posts and composite resin core. The post surface was cleaned with alcohol and treated with different silane coupling agents, being three prehydrolyzed silanes [Silano (Angelus), Prosil (FGM), RelyX Ceramic Primer (3M ESPE)] and one two-component silane [Silane Coupling Agent (Dentsply)]. Two post-silanization air drying temperatures, 23ºC and 60ºC, were applied. A cylindrical plastic matrix was placed around the silanized post and filled with composite resin. Each bonded post provided 7 slices for push-out testing. Each slice was loaded to failure under compression at a cross-head speed of 0.5 mm/min. Data were analyzed by two-way ANOVA and Scott-Knott tests (α=0.05). Dunnett's test was used to compare the mean of the control group with that of each experimental group. Scanning electron microscopy (SEM) was used to evaluate the interface of the fractured slices. For the 23ºC air drying temperature, the use of RelyX Ceramic Primer resulted in significantly lower bond strength than the other silane coupling agents, while the bond strength with Silane Coupling Agent was the highest of all groups. Only with Silane Coupling Agent, the bond strength for the 23ºC air drying temperature was significantly higher than that for 60ºC air drying. In conclusion, the use of warm air drying after silane application produced no increase in the bond strength between the fiber-reinforced composite post and the composite core. The two-component silane produced higher bond strength than all prehydrolyzed silanes when it was used with air drying at room temperature.

  5. The comparison between carboxyl, amido and hydroxy group in influencing electrorheological performance

    Science.gov (United States)

    Li, Huo; Li, Jun-Ran; Liao, Fu-Hui

    2011-03-01

    Three kinds of electrorheological (ER) materials with carboxyl, amido and hydroxyl group, respectively, were synthesized by a simple adsorption method. The powder of silicon dioxide as a substrate of the materials, as well as terephthalic acid [ p-C6H4(COOH)2, abbr.: phen-COOH], p-phenylenediamine [ p-C6H4(NH2)2, abbr.: phen-NH2] and hydroquinone [ p-C6H4(OH)2, abbr.: phen-OH] were chosen as starting materials. The ER properties of suspensions of the materials in silicon oil were studied. The suspension of the material adsorbing phen-COOH reveals the highest ER activity, the relative shear stress of the suspension (25 wt%), τr(=τE/τ0, τE and τ0 are the shear stresses at electric field strengths of E=4.2 and 0 kV/mm, respectively), reaches 220 under a DC electric field at a shear rate of 14.5 s-1. The shear stress of the suspension of the material adsorbing phen-NH2 is the largest at an high electric field strength. The ER activity of the material adsorbing phen-OH is the lowest among the three materials. The molecule structure is an importance factor in influencing ER performance of the materials for similar compounds with different polar function groups. The relationship between the ER activity and dielectric property of the materials was discussed.

  6. The Influence of BMW Group Energy Strategy Communication on Corporate Image

    Directory of Open Access Journals (Sweden)

    Jasna Jurum Kipke

    2004-07-01

    Full Text Available This paper deals with the application of BMW Group energystrategy communication in order to build excellent BMWcorporate image worldwide with the purpose of analyzing thecurrent situation regarding this topic on the Croatian car marketas well as analyzing the possible influence of BMW environmentprotection care and energy strategy on BMW corporateimage in the Republic of Croatia.To ensure sufficient supply of energy in order to meet the futureneeds, the BMW's chosen priorities worldwide are to promoteefficient use of today's available energy sources and to developinnovative solutions for the future. The company usesthese elements in building the desirable BMW corporate image.On the basis of the conducted surve, it was more than obviousthat these activities still do not play a large role in building agood BMW corporate image among BMW customers in Croatia.Obviously, there is great possibility for the BMW Group toimprove its corporate image in Croatia and on the similar marketsboth with the application of intensive environmental careand the energy strategy communication.

  7. Influence of fasting on muscle composition and antioxidant defenses of market-size Sparus macrocephalus

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The study was conducted to investigate fasting effects on flesh composition and antioxidant defenses of market-size Sparus macrocephalus. Two hundred fish (main initial weight 580 g) were divided into two groups (control and fasted) and reared in 6 cages. After two weeks of adaptation, group Ⅰ fasted for 28 d; group Ⅱ was fed normally as a control. In 3, 7, 14, 21 and 28 d,6 fish per group were sampled for proximate flesh composition, liver antioxidant enzyme activities and malondialdehyde flesh content analyses. In fasted fish, the reduction of lipid content in muscle occurred after day 3, and, compared to controls, the content of protein decreased from day 14, the activities of liver antioxidative enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPX) increased from day 3, and flesh malondialdehyde levels increased from day 21. Flesh fat reduction shows that fasting may be used as a technique to reduce flesh lipid content in Sparus macrocephalus. However, considering flesh protein loss and the subsequent oxidative stress, the fasting technique should be used with precautions.

  8. Low shrinkage composite resins: influence on sealing ability in unfavorable C-factor cavities

    Directory of Open Access Journals (Sweden)

    Eliza Burlamaqui Klautau

    2011-02-01

    Full Text Available The present investigation observed the sealing ability of low shrinkage composite resins in large and deep cavities, placed and photocured in one increment. Large, deep cavities (5.0 mm diameter and 2.5 mm deep surrounded by enamel were prepared in bovine teeth, which were then divided into five groups. Groups 1, 2, 3 and 4: acid conditioning + Adper Single Bond (3M/ESPE, St Paul, MN, USA and restoration with Aelite LS Posterior (BISCO Inc. Schaumburg, IL, USA (G1; Filtek Z-350 (3M/ESPE,St Paul, MN, USA (G2; Filtek Z-350 Flow (3M/ESPE, St Paul, MN, USA (G3; Premisa (KERR Corporation, Orange, CA, USA (G4. Group 5: Silorane Adhesive system (3M/ESPE, St Paul, MN, USA + restoration with Filtek Low Shrinkage Posterior P90 (3M/ESPE, St Paul, MN, USA. After polymerization, the teeth were immersed in 0.5% basic fuchsine solution and immediately washed. Using the Imagetool Software, the extent of dye along the margins was calculated as a percentage of total perimeter. The restorations were then transversally sectioned and the depth of dye penetration was calculated in mm, using the same software. Kruskal-Wallis analysis for all groups showed no statistical differences for extent (p = 0.54 or depth (p = 0.8364 of dye penetration. According to this methodology, the so-called low shrinkage composite resins had the same sealing ability compared to regular and flowable nanocomposite materials.

  9. INFLUENCE OF IRRADIATION EXPOSURE TIME ON THE DEPTH CURE OF RESTORATIVE RESIN COMPOSITE

    Directory of Open Access Journals (Sweden)

    Francesca Fabiano

    2014-02-01

    Full Text Available A study was conducted to evaluate the degree of conversion by the hardness measurements of a commercial resin composite. The specimens were prepared according to ISO 4049 and photo-activated for 20s – 40s – 60s with a light-emitting diodes (LEDs. To establish the optimal increment technique mono-layers 1 mm and 2 mm thick were tested. The ratio bottom-to-top was assessed for the mono-layers groups. Vickers hardness profiles were measured for mono-layer, bi-layer and tri-layer along the cross-section. The microhardness map showed difference in the mechanical characteristic of overlying resin confirmed by SEM images analysis of the fracture mechanics. Curing effectiveness of resin composite is not only dependent on the curing light unit but also from thickness of the resin composite and the duration of the exposure. The data suggest that an exposure time of 40 s or higher is required to provide composites with a homogeneous and high hardness, moreover, a 1 mm buildup multi-layering technique results in adequate curing of the bottom layer and better mechanical properties.

  10. Influence of the stacking sequence of layers on the mechanical behavior of polymeric composite cylinders; Influencia da configuracao de bobinagem no comportamento mecanico de cilindros de composito polimerico

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Osni de

    2006-07-01

    This work evaluated experimentally the influence of the stacking sequence of layers symmetrical and asymmetrical on the mechanical behavior of polymeric composite cylinders. For so much, two open-ended cylinders groups were manufactured by filament winding process, which had different stacking sequence related to the laminate midplane, characterizing symmetrical and asymmetrical laminates. The composite cylinders were made with epoxy matrix and carbon fiber as reinforcement. For evaluation of the mechanical strength, the cylinders were tested hydrostatically, which consisted of internal pressurization in a hydrostatic device through the utilization of a fluid until the cylinders burst. Additionally, were compared the strains and failure modes between the cylinders groups. The utilization of a finite element program allowed to conclude that this tool, very used in design, does not get to identify tensions in the fiber direction in each composite layer, as well as interlaminar shear stress, that appears in the cylinders with asymmetrical stacking sequence. The tests results showed that the stacking sequence had influence in the mechanical behavior of the composite cylinders, favoring the symmetrical construction. (author)

  11. Influence of surface treatments to repair recent fillings of silorane-and methacrylate-based composites.

    Science.gov (United States)

    Kaneko, Marina; Caldas, Ricardo Armini; Feitosa, Victor Pinheiro; Xediek Consani, Rafael Leonardo; Schneider, Luis Felipe J; Bacchi, Ataís

    2015-01-01

    The aim of this study was to evaluate the tensile bond strength (TBS) of repairs in recent fillings of methacrylate- (MBC) or silorane-based composites (SBC) subsequent to different surface treatments. Fifty slabs of Filtek P60 (3M ESPE, St Paul, USA) and Filtek P90 (3M ESPE) were stored for 10 days in distilled water at 37°C. The surface of adhesion was abraded with a 600-grit silicone paper and repaired using each respective composite: G1, no treatment (control); G2, application of adhesive; G3, application of silane and adhesive; G4, sandblasting (Al2O3) and adhesive; and G5, sandblasting (Al2O3), silane, and adhesive. Further 10 slabs of each composite were also evaluated for cohesive strength (G6). After 30 days immersion in distilled water at 37°C, the TBS was determined. TBS results were higher for MBC than for SBC (P = 0.00012). The experimental groups were similar for SBC and the TBS was 27% of its cohesive strength. For P60, sandblasting significantly improved the TBS compared to other groups. With MBC, G4 and G5, the TBS was approximately 47% of its cohesive strength. Sandblasting (Al2O3) improves the repair-strength of MBC, whilst for the SBC all treatments succeed. MBC presents higher repair strength than SBC.

  12. Influence of Binder Composition and Concrete Pore Structure on Chloride Diffusion Coefficient in Concrete

    Institute of Scientific and Technical Information of China (English)

    LI Pengping; SU Dagen; WANG Shengnian; FAN Zhihong

    2011-01-01

    The influence of binder composition and pore structure of concrete on chloride diffusion coefficient in concrete were investigated by the natural immersion test, MIP test, SEM and EDS test, respectively. The experimental results showed that the effect of binder composition on chloride diffusion coefficient was the comprehensive result of concrete pore structure and binder hydration products, and the porosity and pore size distribution were the main factors that influence the changes of diffusion coefficient. The chloride diffusion coefficient decreased with increasing the curing temperature and the relative humidity. The hydration degree were promoted by improving curing temperatures, and then the porosity of concrete decreased and the proportion of gel pore and transitional pore increased, respectively. But the water evaporation decreased with increasing the relative humidity and then decreased porosity and increased the proportion of gel pore and transitional pore. Additionally, The chloride diffusion coefficient of concrete got the lower value when the appropriate replacement of fly ash in the ranges of 10%-20%, when the double-adding fly ash and slag content was 50%. The porosity increased and the ratio of C/S in C-S-H decreased with further increasing the fly ash content, which led to increase the chloride diffusion coefficient in concrete.

  13. Influence of mineralogical and heavy metal composition on natural radionuclide concentrations in the river sediments.

    Science.gov (United States)

    Suresh, G; Ramasamy, V; Meenakshisundaram, V; Venkatachalapathy, R; Ponnusamy, V

    2011-10-01

    The natural radiation level has been determined for the sediment samples of the Ponnaiyar River with an aim of evaluating the radiation hazard. The mineralogical characterizations of the sediments have been carried out using the Fourier Transform Infrared (FTIR) spectroscopic technique. The relative distribution of major minerals is determined by calculating extinction coefficient. The concentration and spatial distribution of heavy metals (Pb, Cr, Cu, Zn and Ni) have been studied to understand the heavy metal contamination and its level of toxicity. To evaluate the potential toxicity, heavy metal concentrations are compared with different toxicological and geological reference values. The comparison results suggest that the present metals create an adverse effect on the aquatic ecosystems associated with this river. To assess the sediment contamination due to the studied heavy metals, the Pollution Load Index (PLI) is calculated. Multivariate Statistical analyses (Pearson Correlation, Cluster and Factor analysis) were carried out between the parameters obtained from radioactivity, mineralogical and geochemical analysis to know the existing relations. Obtained results showed that the effect of mineralogy on level of radioactivity should be significant. However, mineralogy effect on heavy metal composition in the sediments should be limited, indicating that other factors such as vicinity of the pollution sources are more important. Also, the influence of mineralogical characterization on level of radioactivity is significant, whereas the influence of the heavy metal composition on level of radioactivity should be limited.

  14. The influence of composition of gypsum plaster on its technological properties

    Directory of Open Access Journals (Sweden)

    M. Pawlak

    2010-10-01

    Full Text Available Gypsum plasters used in art and precision foundry always are the composition of gypsum-silica-cristobalite. It is necessary considering the specifity of plaster during heating stage. Plaster undergoes then, structural transformations causing significant variations of its volume which are nonuniform and proceed with different intensity. The content of silica and cristobalite reduces dimensional variations of setted gypsum plaster what increases dimensional accuracy and significant stresses reduction limiting the possibility of mould cracks occurrence during heating.The influence of cristobalite and silica addition on basic gypsum plaster properties like setting time, dimensional changes after setting, bending strength and permeability in raw and heat treated state are presented in this paper. Experiments were done for mixes containing 30÷70% of the gypsum. It was proven that cristobalite has the biggest influence on the bounding time and expansion of the sandmix and the strength and permeability do not depend on the type of additions and only on theirs total amount in the composition.

  15. The Influence of Ionizing Radiation on Exosome Composition, Secretion and Intercellular Communication.

    Science.gov (United States)

    Jelonek, Karol; Widlak, Piotr; Pietrowska, Monika

    2016-01-01

    A large variety of vesicles is actively secreted into the extracellular space by most type of cells. The smallest nanoparticles (30-120 nm), called exosomes, are known to transport their cargo (nucleic acids, proteins and lipids) between diverse locations in the body. Specific content of exosomes and their influence on recipient cells depends primarily on the type of the secretory (donor) cell, yet several studies highlight the importance of environmental stress on which the donor cells are exposed. Ionizing radiation, which induces damage to DNA and other structures of a target cell, is one of well-recognized stress conditions influencing behavior of affected cells. A few recent studies have evidenced radiationinduced changes in composition of exosomes released from irradiated cells and their involvement in radiation-related communication between cells. Inducible pathways of exosome secretion activated in irradiated cells are regulated by TSAP6 protein (the transmembrane protein tumor suppressor-activated pathway 6), which is transcriptionally regulated by p53, hence cellular status of this major DNA damage response factor affects composition and secretion rate of exosomes released from target cells. Moreover, exosomes released from irradiated cells have been shown to mediate the radiation-induced bystander effect. Understanding radiation-related mechanisms involved in exosome formation and "makeup" of their cargo would shed light on the role of exosomes in systemic response of cells, tissues and organisms to ionizing radiation which may open new perspectives in translational medicine and anticancer-treatment.

  16. The influence of chemical composition on the properties and structure Al-Si-Cu(Mg alloys

    Directory of Open Access Journals (Sweden)

    M. Kaczorowski

    2007-04-01

    Full Text Available The mechanical properties of different chemical composition AlSiCuMg type cast alloys after precipitation hardening are presented. The aim of the study was to find out how much the changes in chemistry of aluminum cast alloys permissible by EN-PN standards may influence the mechanical properties of these alloys. Eight AlSi5Cu3(Mg type cast alloys of different content alloying elements were selected for the study. The specimens cut form test castings were subjected to precipitation hardening heat treatment. The age hardened specimens were evaluated using tensile test, hardness measurements and impact test. Moreover, the structure investigation were carried out using either conventional light Metallography and scanning (SEM and transmission (TEM electron microscopy. The two last methods were used for fractography observations and precipitation process observations respectively. It was concluded that the changes in chemical composition which can reach even 2,5wt.% cause essential differences of the structure and mechanical properties of the alloys. As followed from quantitative evaluation and as could be predicted theoretically, copper and silicon mostly influenced the mechanical properties of AlSi5Cu3(Mg type cast alloys. Moreover it was showed that the total concentration of alloying elements accelerated and intensifies the process of decomposition of supersaturated solid solution. The increase of Cu and Mg concentration increased the density of precipitates. It increases of strength properties of the alloys which are accompanied with decreasing in ductility.

  17. Influence of thermomechanical processing on the structure and properties of Cu-Ag alloy in situ composites

    Institute of Scientific and Technical Information of China (English)

    NING; Yuan-tao; ZHANG; Xiao-hui; ZHANG; Jie

    2005-01-01

    The influences of the thermomechanical processing, including the solidification conditions, the cold deformation and the intermediate annealing treatment, on the structure and properties of the Cu-10Ag alloy in situ composite were studied in this paper. The cast structure and the structural changes in the cold deformation and intermediate annealing process were observed. The properties including the ultimate tensile strength (UTS) and the electrical conductivity were determined. A two-stage strain strengthening effect for the Cu-10Ag alloy in situ filamentary composite was observed. The factors influencing the UTS and conductivity were discussed. The solidification conditions in the range of 10-1000 K/s cooling rates and the intermediate heat treatment showed obviously influence on the structure and properties on the Cu-10Ag alloy in situ filamentary composite. The typical properties of the Cu-Ag alloy in situ filamentary composites through thermomechanical processing were reported.

  18. Morphological Composition of z~0.4 groups: The site of S0 formation

    CERN Document Server

    Wilman, D J; Mulchaey, J S; McGee, S L; Balogh, M L; Bower, R G

    2008-01-01

    The low redshift Universe (z99.999% confidence. Indeed the S0 fraction in groups is at least as high as in z~0.4 clusters and X-ray selected groups, which have more luminous Intra Group Medium (IGM). An 97% confident excess of S0s at >=0.3Mpc from the group centre at fixed luminosity, tells us that formation is not restricted to, and possibly even avoids, the group cores. Interactions with a bright X-ray emitting IGM cannot be important for the formation of the majority of S0s in the Universe. In contrast to S0s, the fraction of elliptical galaxies in groups at fixed luminosity is similar to the field, whilst the brightest ellipticals are strongly enhanced towards the group centres (>99.999% confidence within 0.3Mpc). We conclude that the group and sub-group environments must be dominant for the formation of S0 galaxies, and that minor mergers, galaxy harassment and tidal interactions are the most likely responsible mechanisms. This has implications not only for the inferred pre-processing of cluster galaxies...

  19. Influence of metal-ceramic interfaces on the behaviour of metal matrix composites and their joints

    Energy Technology Data Exchange (ETDEWEB)

    Urena, A. [Universidad Complutense de Madrid (Spain). Facultad de Ciencias Quimicas; Gomez de Salazar, J.M. [Universidad Complutense de Madrid (Spain). Facultad de Ciencias Quimicas; Escalera, M.D. [Universidad Complutense de Madrid (Spain). Facultad de Ciencias Quimicas

    1997-06-01

    The present contribution emphasises the importance of the chemical reactions which occur during the fabrication and joining procedures, in the metallic matrix/ceramic reinforcement interfaces of the metal matrix composites. Using both the experimental data obtained by other investigators studding metal/ceramic systems such us Al/SiC, Al-Mg/Al{sub 2}O{sub 3}, Ti/SiC, etc.; and the results of the research carried out for the present authors in the diffusion bonding of Al/SiC and Al-Mg/Al{sub 2}O{sub 3} composites, the nature of these chemical reactions and their influence on the MMC properties are discussed. Authors also study the particularly case of the participation of Li in the interface reactions occurred in the Al/SiC system. For it, the data obtained in the study of the diffusion bonding of an aluminium-copper alloy (AA2124) reinforced with SiC whiskers and using an aluminium-lithium alloy (AA8090) as interlayer, are used. TEM observations showed that Li might change the nature of this interface and penetrate in the SiC lattice. It can answer to the increase in interface strength detected by other authors in Al-Li/SiC composites. The application of TEM has proved to be an essential tool for characterisation of these kind of interfaces. (orig.)

  20. Influence of current density on microstructure and properties of electrodeposited nickel-alumina composite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Góral, Anna, E-mail: a.goral@imim.pl [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta St., 30-059 Krakow (Poland); Nowak, Marek [Institute of Non-Ferrous Metals Gliwice, Light Metals Division Skawina, 19 Pilsudskiego St., 32-050 Skawina (Poland); Berent, Katarzyna; Kania, Bogusz [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta St., 30-059 Krakow (Poland)

    2014-12-05

    Highlights: • Current density of the electrodeposition affects the incorporation of Al{sub 2}O{sub 3} in Ni matrix. • Ni/Al{sub 2}O{sub 3} composite coatings exhibit changes in crystallographic texture. • The pitting corrosion effects were observed in Ni/Al{sub 2}O{sub 3} coatings. • Residual stresses were decreased with increasing current density and coating thickness. - Abstract: Electrodeposition process is a very promising method for producing metal matrix composites reinforced with ceramic particles. In this method insoluble particles suspended in an electrolytic bath are embedded in a growing metal layer. This paper is focused on the investigations of the nickel matrix nanocomposite coatings with hard α-Al{sub 2}O{sub 3} nano-particles, electrochemically deposited from modified Watts-type baths on steel substrates. The influence of various current densities on the microstructure, residual stresses, texture, hardness and corrosion resistance of the deposited nickel/alumina coatings was investigated. The surface morphology, cross sections of the coatings and distribution of the ceramic particles in the metal matrix were examined by scanning electron microscopy. The phase composition, residual stresses and preferred grain orientation of the coatings were characterized using X-ray diffraction techniques. The coating morphology revealed that α-Al{sub 2}O{sub 3} particles show a distinct tendency to form agglomerates, approximately uniformly distributed into the nickel matrix.

  1. Influences of interfacial damage on the effective wave velocity in composites with reinforced particles

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The scattering of elastic waves by a spherical particle with imperfect interface and the multiple scattering by many spherical particles with imperfect interface are studied in this paper. First,the scattering of elastic waves by a spherical particle with imperfect interface,i.e. spring interface model,is studied. Then,the multiple scattering by random distributed particles with interfacial damage in a composite material is investigated. The equations to evaluate velocity and attenuation of effective waves defined by statistic averaging are given. Furthermore,based on the established relation between the effective velocity and interfacial constants,a method to evaluate the interfacial damage nondestructively from the ultrasonic measure data is proposed. The numerical simulation is performed for the Sic-Al composites. The effective velocity is computed to show the influences of interface damage. By using the genetic algorithm,the interfacial damage is evaluated from the synthetic experimental data with various levels of error. The numerical results show the feasibility of the method proposed to approximately evaluate the interfacial damage in a composite material with reinforced particles based on ultrasonic data.

  2. Parametric study of influence of stiffener variables on postbuckling response of frame-stiffened composite panels

    Science.gov (United States)

    Sanz-Douglass, Gabriela J.

    Traditional aircraft composite stiffened panels are designed to avoid buckling of the skin at service loads, to prevent initiation and growth of delamination damages. In stitched composites, the stitching provides reinforcement against delamination; therefore, the structure can be designed for operation in a post buckled state with local skin buckling. The novel stitched stiffened composite panel concept titled Pultruded-Rod Stiffened Efficient Unitized Structure, PRSEUS, was designed specifically for operating in the postbuckling regime, yet the nonlinear postbuckling behavior of PRSEUS has not been explored fully. This thesis presents a finite element analysis based trade study to understand influence of frame stiffener design variables on the nonlinear postbuckling response of the PRSEUS panel concept. The trade study allowed exploration of the design space as a first step towards design optimization. It also allowed discovery of some of the challenges of post processing that must be addressed to enable an automated surrogate based design optimization of the PRESUS stiffened panel concept for operation in postbuckling regimes.

  3. How surface composition of high milk proteins powders is influenced by spray-drying temperature.

    Science.gov (United States)

    Gaiani, C; Morand, M; Sanchez, C; Tehrany, E Arab; Jacquot, M; Schuck, P; Jeantet, R; Scher, J

    2010-01-01

    High milk proteins powders are common ingredients in many food products. The surface composition of these powders is expected to play an essential role during their storage, handling and/or final application. Therefore, an eventual control of the surface composition by modifying the spray-drying temperature could be very useful in the improvement of powder quality and the development of new applications. For this purpose, the influence of five spray-drying temperatures upon the surface composition of the powders was investigated by X-ray photoelectron spectroscopy. The major milk proteins were studied: native micellar casein and native whey, both more or less enriched in lactose. The results show a surface enrichment in lipids for all the powders and in proteins for many powders. Whatever the drying temperature, lipids and proteins are preferentially located near the surface whereas lactose is found in the core. This surface enrichment is also highly affected by the spray-drying temperature. More lipids, more proteins and less lactose are systematically observed at the surface of powders spray-dried at lower outlet air temperatures. The nature of proteins is also found essential; surface enrichment in lipids being much stronger for whey proteins containing powders than for casein containing powders. Additionally, we found a direct correlation between the lipids surface concentration and the wetting ability for the 25 powders studied.

  4. Influence of cultivated landscape composition on variety resistance: an assessment based on wheat leaf rust epidemics.

    Science.gov (United States)

    Papaïx, Julien; Goyeau, Henriette; Du Cheyron, Philippe; Monod, Hervé; Lannou, Christian

    2011-09-01

    In plant pathology, the idea of designing variety management strategies at the scale of cultivated landscapes is gaining more and more attention. This requires the identification of effects that take place at large scales on host and pathogen populations. Here, we show how the landscape varietal composition influences the resistance level (as measured in the field) of the most grown wheat varieties by altering the structure of the pathogen populations. For this purpose, we jointly analysed three large datasets describing the wheat leaf rust pathosystem (Puccinia triticina/Triticum aestivum) at the country scale of France with a Bayesian hierarchical model. We showed that among all compatible pathotypes, some were preferentially associated with a variety, that the pathotype frequencies on a variety were affected by the landscape varietal composition, and that the observed resistance level of a variety was linked to the frequency of the most aggressive pathotypes among all compatible pathotypes. This data exploration establishes a link between the observed resistance level of a variety and landscape composition at the national scale. It illustrates that the quantitative aspects of the host-pathogen relationship have to be considered in addition to the major resistance/virulence factors in landscape epidemiology approaches.

  5. Influence of constant and ac electric fields on ferromagnetic resonance in magnetoelectric composites

    Science.gov (United States)

    Tatarenko, A. S.; Bichurin, M. I.; Petrov, V. M.; Fillipov, D. A.; Srinivasan, G.

    2004-03-01

    A composite of ferromagnetic and ferroelectric phases is expected to show magnetoelectric coupling that is mediated by mechanical deformation. For such composites, we proposed a model to treat the magnetoelectric (ME) coupling at frequencies corresponding to ferromagnetic resonance (FMR) [1,2]. The effect manifests as a shift in the resonance field when subjected to a constant electric field. Here we discuss a theory for the influence of both dc and high frequency electric fields on FMR in the composites. The model predicts a significant increase in the strength of ME coupling when the electric field is tuned to the electromechanical resonance (EMR) frequency. We assume the composite to be a homogeneous medium. By solving combined elastostatics, electrostatics and magnetostatics equations, we estimate the ME constants using effective parameters. The calculations are for 3-0, 0-3 and 2-2 connectivities. Expressions for ME coefficients are obtained as a function of interface coupling and the volume fraction for the piezoelectric phase. Under the influence of a constant electric field E, our model predicts a shift in the ferromagnetic resonance field that is proportional to ME constants. In the presence of an ac electric field, we estimate a strong ME coupling when the frequency is tuned to EMR. As an example, the FMR field shift at 9.3 GHz due an ac electrical field tuned to EMR at 350 kHz is determined for multilayer and bulk composites of nickel ferrite - lead zirconate titanate. It is shown that ME interactions are enhanced by several orders of magnitude compared to off resonance values. 1. M.I. Bichurin, I. A. Kornev, V. M. Petrov, A. S. Tatarenko, Yu. V. Kiliba, and G. Srinivasan. Phys. Rev. B 64, 094409 (2001). 2. M.I. Bichurin, V. M. Petrov, Yu. V. Kiliba, and G. Srinivasan. Phys. Rev. B 66, 134404 (2002). - supported by grants from the Russian Ministry of Education (Å02-3.4-278), the Universities of Russia Foundation (UNR 01.01.007), and the National Science

  6. Influence of modification in core building procedure on fracture strength and failure patterns of premolars restored with fiber post and composite core.

    Science.gov (United States)

    Kim, Young-Hoi; Lee, Jong-Hyuk

    2012-02-01

    The influence of the modified process in the fiber-reinforced post and resin core foundation treatment on the fracture resistance and failure pattern of premolar was tested in this study. Thirty-six human mandibular premolars were divided into 4 groups (n = 9). In group DCT, the quartz fibre post (D.T. Light-post) was cemented with resin cement (DUO-LINK) and a core foundation was formed with composite resin (LIGHT-CORE). In group DMO and DMT, resin cement (DUO-LINK) was used for post (D.T. Light-post) cementation and core foundation; in group DMO, these procedures were performed simultaneously in one step, while DMT group was accomplished in separated two steps. In group LCT, the glass fiber post (LuxaPost) cementation and core foundation was accomplished with composite resin (LuxaCore-Dual) in separated procedures. Tooth were prepared with 2 mm ferrule and restored with nickel-chromium crowns. A static loading test was carried out and loads were applied to the buccal surface of the buccal cusp at a 45 degree inclination to the long axis of the tooth until failure occurred. The data were analyzed with MANOVA (α = .05). The failure pattern was observed and classified as either favorable (allowing repair) or unfavorable (not allowing repair). The mean fracture strength was highest in group DCT followed in descending order by groups DMO, DMT, and LCT. However, there were no significant differences in fracture strength between the groups. A higher prevalence of favorable fractures was detected in group DMT but there were no significant differences between the groups. The change of post or core foundation method does not appear to influence the fracture strength and failure patterns.

  7. Batch cooling crystallization and pressure filtration of sulphathiazole: the influence of solvent composition.

    Science.gov (United States)

    Häkkinen, Antti; Pöllänen, Kati; Karjalainen, Milja; Rantanen, Jukka; Louhi-Kultanen, Marjatta; Nyström, Lars

    2005-02-01

    Currently there is a great interest in new process analytical approaches to increase the process understanding of pharmaceutical unit operations. In the present study, the influence of the solvent composition on the material properties and, further, on the filtration characteristics, of different crystal suspensions obtained through an unseeded batch-cooling-crystallization process was studied. Sulphathiazole, which is an antibiotic agent with multiple polymorphic forms, was produced by performing laboratory-scale cooling crystallization experiments from five different mixtures of water and propan-1-ol (n-propanol). The size, shape and polymorphic composition of the crystals produced were characterized with a scanning electron microscope, with a novel automated image analyser and with an X-ray powder diffractometer. All of the monitored crystal properties were found to clearly differ between the samples obtained from different solvents. The crystals produced in the batch-cooling-crystallization experiments were separated from the crystallizing solvents using a batch-type pressure Nutsche filter, and the filtration characteristics of the suspensions were evaluated on the basis of average filter-cake porosities and average specific cake resistances, which were determined from the experimentally obtained filtration data. Comparison between the calculated filtration characteristics revealed that considerable differences existed between the different suspensions, and it could therefore be concluded that the pressure-filtration process was influenced by the composition of the crystallizing solvent. The filterability of all the studied sulphathiazole suspensions was considered to be rather good on the basis of the relatively low cake porosities (0.51-0.63), which were accompanied with low average specific cake resistances [(8.7 x 10(7))-(1.2 x 10(9)) m/kg].

  8. Factors Influencing Graft Choice in Revision Anterior Cruciate Ligament Reconstruction in the MARS Group.

    Science.gov (United States)

    Group, Mars

    2016-08-01

    It has not been known what drives revision anterior cruciate ligament (ACL) reconstruction graft choice in the past. We undertook this study to utilize the Multicenter ACL Revision Study (MARS) group and propensity score statistical analysis to determine the drivers of revision ACL reconstruction graft choice. We hypothesized that propensity analysis would demonstrate that individual surgeons still have significant impact on revision ACL reconstruction. Twelve hundred patients were enrolled in this longitudinal revision cohort by 83 surgeons at 52 sites. The median age was 26 years and 505 (42%) were females. One thousand forty-nine (87%) patients were undergoing their first ACL revision. Graft choice for revision ACL reconstruction for these patients was 48% autograft, 49% allograft, and 3% combination. The independent variables of this model included gender, age, ethnicity, body mass index, smoking status, sport, activity level, previous graft, revision number, surgeon, surgeon's opinion of failure, previous technical aspects, etc. Surgeons were defined as those who contributed more than 15 patients during the enrollment period. . We calculated a propensity score for graft type based on the predicted probability of receiving an allograft from a logistic regression model. Propensity scores demonstrated that surgeon, prior graft choice, and patient age each had significant influence on which graft type was chosen for the revision ACL reconstruction (p  allograft was 3.6 times more likely to be chosen for the revision. This current study demonstrates that the individual surgeon is ultimately the most important factor in revision ACL reconstruction graft choice. Additional statistically significant influences of graft choice included age, gender, previous graft choice, ACL revision number, concurrent medial collateral ligament/posteromedial repair, and opinion of the previous failure. This demonstrates that if graft choice is determined to impact outcome then

  9. Research on the Influence of Size Effect for the mechanical Performance of GFRP tube concrete steel tube composite column under axial compression

    Science.gov (United States)

    Li, Wen; Wang, Tong; Na, Yu

    2017-08-01

    FRP tube-concrete-steel tube composite column (DSTC) was a new type of composite structures. The column consists of FRP outer tube and steel tube and concrete. Concrete was filled between FRP outer tube and steel tube. This column has the character of light and high strength and corrosion resistance. In this paper, properties of DSTC axial compression were studied in depth. The properties were studied by two groups DSTC short columns under axial compression performance experiment. The different size of DSTC short columns was importantly considered. According to results of the experiment, we can conclude that with the size of the column increases the ability of it to resist deformation drops. On the other hand, the size effect influences on properties of different concrete strength DSTC was different. The influence of size effect on high concrete strength was less than that of low concrete.

  10. INFLUENCE OF CSN3 MARKER ON MILK COMPOSITION IN ROMANIAN BROWN AND ROMANIAN SIMMENTAL CATTLE FROM S.C.D.C.B. ARAD

    Directory of Open Access Journals (Sweden)

    DANIELA E. ILIE

    2013-07-01

    Full Text Available Milk yield and composition in cattle are typical quantitative traitswhich are influenced by environmental factors and allelic variations. K-casein is a protein expressed in milk and, due to is polymorphism, may serve as a molecular marker for yield, composition and technological properties of milk. The objective of this study was to compare the relation between the genetic marker CSN3 (k-casein and the observed milk traits in selected cattle groups. In our study we analyzed the milk traits of 32 Romanian Brown dairy cows and 54 Romanian Simmental dairy cows. The experiments described in this paper show clear evidence that -CSN3 genotype is involved in milk protein enrichment. The CSN3 gene of BB genotype showed a grate influence on protein yield. The relation between CSN3 genotype and milk protein was found to be significant in both cattle breed.

  11. Conditioning materials with biomacromolecules: composition of the adlayer and influence on cleanability.

    Science.gov (United States)

    Touré, Yetioman; Genet, Michel J; Dupont-Gillain, Christine C; Sindic, Marianne; Rouxhet, Paul G

    2014-10-15

    The influence of substrate hydrophobicity and biomacromolecules (dextran, bovine serum albumin - BSA) adsorption on the cleanability of surfaces soiled by spraying aqueous suspensions of quartz particles (10-30μm size), then dried, was investigated using glass and polystyrene as substrates. The cleanability was evaluated using radial flow cell (RFC). The surface composition was determined by X-ray photoelectron spectroscopy (XPS). The interpretation of XPS data allowed the complexity due to the ubiquitous presence of organic contaminants to be coped with, and the surface composition to be expressed in terms of both the amount of adlayer and the mass concentration of adlayer constituents. When soiled with a suspension of particles in water, glass was much less cleanable than polystyrene, which was attributed to its much lower water contact angle, in agreement with previous observations on starch soil. Dextran was easily desorbed and did not affect the cleanability. The presence of BSA at the interface strongly improved the cleanability of glass while the contact angle did not change appreciably. In contrast, soiling polystyrene with quartz particles suspended in a BSA solution instead of water did not change markedly the cleanability, while the contact angle was much lower and the aggregates of soiling particles were more flat. These observations are explained by the major role of capillary forces developed upon drying, which influence the closeness of the contact between the soiling particles and the substrate and, thereby, the adherence of particles. The capillary forces are proportional to the liquid surface tension and depend in a more complex way on contact angles of the particles and of the substrate. The dependence of cleanability on capillary forces, and in particular on the liquid surface tension, is predominant as compared with its dependence on the size and shape of the soiling aggregates, which influence the efficiency of shear forces exerted by the

  12. The influence of composition of porous copolyester scaffolds on reactions induced by irradiation sterilization.

    Science.gov (United States)

    Odelius, Karin; Plikk, Peter; Albertsson, Ann-Christine

    2008-01-01

    In our previous work regarding radiation sterilization of porous scaffolds we have concluded that the composition and microstructure of the polymer chain are a key factor influencing the degradation reactions occurring upon irradiation. In this work we in contrast reported on the effects of high-energy irradiation on the thermal and mechanical properties. Electron beam (EB)- and gamma-irradiation sterilization were used in order to finalize the properties of a series of porous scaffolds comprised of different aliphatic polyester copolymers. The results presented here show that, for both sterilization methods, the crystallinity increased for all copolymers of 1,5-dioxepan-2-one (DXO) and l,l-lactide (LLA) at the minimum sterilization dose. The same was true of the epsilon-caprolactone (CL)- and LLA-containing copolymers upon EB sterilization, while a reduction in crystallinity were found upon gamma-irradiation. As was anticipated, it was shown that crystallinity also is a characteristic of the copolymer influencing the effects of the irradiation-induced reactions. Both the onset temperature and the temperature corresponding to the maximum rate of weight loss increased after irradiation and hence the thermal stability was increased. This is a result of a simultaneous lengthening of the chains by cross-linking reactions and a shortening by random chain-scissions occurring throughout the molecule, which lead to the formation of new endgroups with higher thermal stability. Scaffolds of crystalline polymers retained more of their initial tensile properties after irradiation compared to amorphous materials. The result previously published, showing that the composition was a key factor influencing the degradation reactions occurring upon irradiation, was augmented here.

  13. The influence of hydrodynamic diameter and core composition on the magnetoviscous effect of biocompatible ferrofluids.

    Science.gov (United States)

    Nowak, J; Wiekhorst, F; Trahms, L; Odenbach, S

    2014-04-30

    Suspensions of magnetic nanoparticles have received increasing interest in the biomedical field. While these ferrofluids are already used for magnetic resonance imaging, emerging research on cancer treatment focuses, for example, on employing the particles as drug carriers, or using them in magnetic hyperthermia to destroy diseased cells by heating of the particles. To enable safe and effective applications, an understanding of the flow behaviour of the ferrofluids is essential. Regarding the applications mentioned above, in which flow phenomena play an important role, viscosity under the influence of an external magnetic field is of special interest. In this respect, the magnetoviscous effect (MVE) leading to an increasing viscosity if an external magnetic field of a certain strength is applied, is well-known for singlecore ferrofluids used in the engineering context. In the biomedical context, multicore ferrofluids are preferred in order to avoid remanence magnetization and to enable a deposition of the particles by the organism without complications. This study focuses on a comparison of the MVE for three ferrofluids whose composition is identical except in relation to their hydrodynamic diameter and core composition-one of the fluids contains singlecore particles, while the other two feature multicore particles. This enables confident conclusions about the influence of those parameters on flow behaviour under the influence of a magnetic field. The strong effects found for two of the fluids should be taken into account, both in future investigations and in the potential use of such ferrofluids, as well as in manufacturing, in relation to the optimization of flow behaviour.

  14. Influence of light-polymerization modes on the degree of conversion and mechanical properties of resin composites: a comparative analysis between a hybrid and a nanofilled composite.

    Science.gov (United States)

    da Silva, Eduardo Moreira; Poskus, Laiza Tatiana; Guimarães, José Guilherme Antunes

    2008-01-01

    This study analyzed the influence of the light polymerization mode on the degree of conversion (DC) and mechanical properties of two resin composites: a hybrid (Filtek P60) and a nanofilled composite (Filtek Supreme). The composites were light activated by three light polymerization modes (Standard-S: 650 mW/cm2 for 30 seconds; High intensity-H: 1000 mW/cm2 for 20 seconds and Gradual-G: 100 up to 1000 mW/cm2 for 10 seconds + 1000 mW/cm2 for 10 seconds). The DC (%) was measured by FT-Raman spectroscopy. Flexural strength and flexural modulus were obtained from bar-shaped specimens (1 x 2 x 10 mm) submitted to the three-point bending test. Microhardness was evaluated by Knoop indentation (KHN). Data were analyzed by ANOVA and Student-Newman-Keuls multiple range test and linear regression analysis. The results showed the following DC: H > S > G (p hybrid > nanofilled (p S = G (p hybrid composite presented higher flexural strength and flexural modulus than the nanofilled composite (p composites (p = 0.1605). The results suggest that nanofilled composites may present a lower degree of conversion and reduced mechanical properties compared to hybrid composites.

  15. Studying the influence of nanodiamonds over the elasticity of polymer/nanodiamond composites for biomedical application

    Science.gov (United States)

    Hikov, T.; Mitev, D.; Radeva, E.; Iglic, A.; Presker, R.; Daniel, M.; Sepitka, J.; Krasteva, N.; Keremidarska, M.; Cvetanov, I.; Pramatarova, L.

    2014-12-01

    The combined unique properties offered by organic and inorganic constituents within a single material on a nanoscale level make nanocomposites attractive for the next generation of biocompatible materials. The composite materials of the detonation nanodiamond/polymer type possess spatial organization of components with new structural features and physical properties, as well as complex functions due to the strong synergistic effects between the nanoparticles and the polymer [1]. The plasma polymerization (PP) method was chosen to obtain composites of silicon-based polymers, in which detonation generated nanodiamond (DND) particles were incorporated. The composite layers are homogeneous, chemically resistant, thermally and mechanically stable, thus allowing a large amount of biological components to be loaded onto their surface and to be used in tissue engineering, regenerative medicine, implants, stents, biosensors and other medical and biological devices. Mesenchymal stem cells (MSCs) are the main focus of research in regenerative medicine due to their extraordinary potential to differentiate into different kinds of cells including osteoblasts, which are needed for various bone disease treatments. However, for optimal usage of MSCs knowledge about the factors that influence their initial distribution in the human system, tissue-specific activation and afterwards differentiation into osteoblasts is required. In recent studies it was found that one of these factors is the elasticity of the substrates [2]. The choice of the proper material which specifically guides the differentiation of stem cells even in the absence of growth factors is very important when building modern strategy for bone regeneration. One of the reasons for there not being many studies in this area worldwide is the lack of suitable biomaterials which support these kinds of experiments. The goal of this study is to create substrates suitable for cell culture with a range of mechanical properties

  16. Influence of cassava genotype and composite flours’ substitution level on rheological behaviour during bread-making

    Directory of Open Access Journals (Sweden)

    Sergio Henao Osorio

    2010-05-01

    Full Text Available Given increasing dependence on imported wheat, studies have been carried out in Colombia regarding the use of composite wheat-cassava flour in bread-making. A project was carried out from 1986-1991 in which different cassava genotypes, harvest ages, substitution levels and bread acceptability were evaluated. However, these studies did not have any effect on the baking sector because a constant supply of high quality, high volume and reasonably-priced cassava flour was lacking. Based on these studies, this work was aimed at determining the influence of three industrial cassava market genotypes (CMC-40, HMC-1, MCOL-1505, using four wheat-cassava flour composite substitution levels (0%, 5%, 10%, 15% regarding the rheological and fermentative characteristics of dough in bread-making. Farinogram, alveogram, amylogram and falling number index analysis were analysed. Specific volume and acceptability of three types of bread (common, mold and hamburger were evaluated. It was determined that composite flours had higher fiber and reduced sugar content than the wheat flour pattern, thereby increasing wa-ter absorption and available sugar content during fermentation. Dough development time for the composite flours was half the a-verage required for wheat flour and the tolerance index was higher; its stability became reduced due to increased substitution le-vels and its firmness increased due to a rise in water absorption. Falling number values came within an acceptable range (250-400 s. The specific volume of all bread having 5% and 10% substitution was higher than that for the pattern. The best general acceptability was assigned to common and mold type bread from all varieties and substitution levels.

  17. The influence of precipitation temperature on the properties of ceria–zirconia solid solution composites

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Yajuan [College of Architecture and Environment, Sichuan University, Chengdu 610065, Sichuan (China); Fang, Ruimei; Shang, Hongyan [College of Chemical Engineering, Sichuan University, Chengdu 610064, Sichuan (China); Shi, Zhonghua; Gong, Maochu [Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, Sichuan (China); Center of Engineering of Vehicular Exhaust Gases Abatement, Chengdu 610064, Sichuan (China); Center of Engineering of Environmental Catalytic Material, Chengdu 610064, Sichuan (China); Chen, Yaoqiang, E-mail: nic7501@scu.edu.cn [College of Architecture and Environment, Sichuan University, Chengdu 610065, Sichuan (China); College of Chemical Engineering, Sichuan University, Chengdu 610064, Sichuan (China); Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, Sichuan (China); Center of Engineering of Vehicular Exhaust Gases Abatement, Chengdu 610064, Sichuan (China); Center of Engineering of Environmental Catalytic Material, Chengdu 610064, Sichuan (China)

    2015-04-15

    Highlights: • The crystallite size of precipitate increases as the precipitation temperature rises. • The stack of large crystallite can form nanoparticles with big pore size. • Big pore sizes are advantageous to improve the thermal stability. • Phase segregation is restricted in CZ solid solution precipitated at 70 °C. • The reducibility and OSC of the solid solution precipitated at 70 °C are improved. - Abstract: The ceria–zirconia composites (CZ) with a Ce/Zr mass ratio of 1/1 were synthesized by a back-titration method, in which the influence of precipitation temperature on the properties of ceria–zirconia precipitates was investigated. The resulting precipitation and mixed oxides at different precipitation temperatures were then characterized by a range of techniques, including textural properties, X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), H{sub 2}-temperature programmed reduction (H{sub 2}-TPR) as well as oxygen storage capacity (OSC) measurement. The results revealed that ceria–zirconia composites were formed as solid solution and such structure is favored of thermostability and texture properties. In particular, the composite CZ-70 synthesized at 70 °C exhibited prominent thermostability with a surface area of 32 m{sup 2}/g as well as a pore volume of 0.15 cc/g after aging treatment at 1000 °C for 5 h. And this was found to be associated with the wider pore size distribution which maybe owed to the formation of large crystal at the primary stage of precipitation. Additionally, the composite CZ-70 showed excellent reduction property and OSC benefiting from stable texture and structure.

  18. Temporary Versus Permanent Group Membership : How the Future Prospects of Newcomers Affect Newcomer Acceptance and Newcomer Influence

    NARCIS (Netherlands)

    Rink, Floor A.; Ellemers, Naomi

    2009-01-01

    Three studies examine how the future prospects of new group members affect newcomer acceptance and newcomer influence. In Study 1, participants anticipate accepting temporary newcomers less easily than permanent newcomers because they expect temporary newcomers to differ from the group. In Study 2,

  19. Some Influences of Family Group Therapy on the Rehabilitation Potential of Clients. A Delgado Research Study. Final Report.

    Science.gov (United States)

    Galloway, John P.; Goldstein, Harris K.

    The Delgado Rehabilitation Center, New Orleans, Louisiana, conducted this study to determine the influence of family therapy on clients receiving rehabilitation services at the Center. An experimental group of randomly selected relatives of 33 clients received group therapy while 39 other randomly selected relatives served as controls. Criteria…

  20. Predator biomass, prey density, and species composition effects on group size in recruit coral reef fishes

    Science.gov (United States)

    DeMartini, Edward E.; Anderson, Todd W.; Friedlander, Alan M.; Beets, James P.

    2011-01-01

    Group incidence and size are described for recruit parrotfishes, wrasses, and damselfishes on Hawaiian reefs over 3 years (2006–2008) at sites spanning the archipelago (20–28°N, 155–177°W). Coral-poor and coral-rich areas were surveyed at sites with both low (Hawaii Island) and high (Midway Atoll) predator densities, facilitating examination of relations among predator and recruit densities, habitat, and group metrics. Predator and recruit densities varied spatially and temporally, with a sixfold range in total recruit densities among years. Group (≥2 recruits) metrics varied with time and tracked predator and recruit densities and the proportion of schooling species. Groups often included heterospecifics whose proportion increased with group size. A non-saturating relationship between group size and recruit density suggests that the anti-predator benefits of aggregation exceeded competitive costs. Grouping behavior may have overarching importance for recruit survival—even at high recruit densities—and merits further study on Hawaiian reefs and elsewhere.