WorldWideScience

Sample records for resistant composite concepts

  1. The impact of a 12-week resistance training program on strength, body composition, and self-concept of Hispanic adolescents.

    Science.gov (United States)

    Velez, Amelia; Golem, Devon L; Arent, Shawn M

    2010-04-01

    Current evidence suggests that a resistance training program may be physically and psychologically beneficial for adolescents. The purpose of this study was to examine the effects of a structured resistance training program on strength, body composition, and self-concept in normal and overweight Hispanic adolescents. Male and female participants (n = 28; 16.1 +/- 0.2 y; 164.5 +/- 1.4 cm; 63.3 +/- 2.5 kg; 20.0 +/- 1.7% body fat [BF]) were recruited from a predominantly Hispanic high school. Prior to the 12-week program, strength, body composition, and self-concept were assessed. Subjects were randomly assigned to a control group (CON; n = 15) or to a resistance training group (RT; n = 13) that participated in supervised strength training 3 days/week. All measures were repeated at the end of the 12-week program. RT had significantly greater strength increases for bench press (p increased %BF. RT had an increase in condition/stamina competence (p = 0.008), attractive body adequacy (p = 0.017), and global self-worth (p = 0.013) from pretest to posttest, whereas no change was observed for CON. In conclusion, resistance training resulted in significant physiological and psychological improvements in Hispanic adolescents compared to typical school-based activities. These findings indicate that resistance training can be incorporated into the activities of Hispanic adolescents to promote improved health and fitness.

  2. Corrosion resistant composite materials

    International Nuclear Information System (INIS)

    Ul'yanin, E.A.

    1986-01-01

    Foundations for corrosion-resistant composite materials design are considered with account of components compatibility. Fibrous and lamellar composites with metal matrix, dispersion-hardened steels and alloys, refractory metal carbides-, borides-, nitrides-, silicides-based composites are described. Cermet compositions and fields of their application, such as protective coatings for operation in agressive media at high temperatures, are presented

  3. Can resistance training change the strength, body composition and self-concept of overweight and obese adolescent males? A randomised controlled trial.

    Science.gov (United States)

    Schranz, Natasha; Tomkinson, Grant; Parletta, Natalie; Petkov, John; Olds, Tim

    2014-10-01

    Resistance training is an exercise modality at which overweight and obese adolescents can excel and which can therefore positively affect their psychological well-being. The aim of this study was to determine the effect of a 6-month resistance training intervention on the self-concept strength and body composition of overweight and obese adolescent males. 56 overweight and obese males aged 13-17 years were randomly allocated to an Intervention (n=30) or Control (n=26) group. Primary (psychological) and secondary (strength and body composition) outcomes were assessed at baseline as well as at 3 (halfway through the intervention), 6 (immediately postintervention) and 12 months follow-up. Random effects mixed modelling was used to determine the effects of the intervention. Statistically significant differences between the Intervention and Control groups were observed at 3-month and 6-month assessments for exercise self-efficacy, resistance training confidence and self-esteem. Large increases in strength for the Intervention group, relative to Controls, were also observed with no substantial changes in body composition shown for either group. Values for all variables returned to baseline following completion of the programme. A 6-month resistance training intervention can positively affect the self-concept and strength of overweight and obese adolescent boys. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  4. Extending Profiles with Stereotypes for Composite Concepts

    OpenAIRE

    Quartel, Dick; Dijkman, R.M.; van Sinderen, Marten J.; Briand, L.; Williams, C.

    2005-01-01

    This paper proposes an extension of the UML 2.0 profiling mechanism. This extension facilitates a language designer to introduce composite concepts as separate conceptual and notational elements in a modelling language. Composite concepts are compositions of existing concepts. To facilitate the introduction of composite concepts, the notion of stereotype is extended. This extension defines how a composite concept can be specified and added to a language’s metamodel, ithout modifying the exist...

  5. Extending Profiles with Stereotypes for Composite Concepts

    NARCIS (Netherlands)

    Quartel, Dick; Dijkman, R.M.; van Sinderen, Marten J.; Briand, L.; Williams, C.

    2005-01-01

    This paper proposes an extension of the UML 2.0 profiling mechanism. This extension facilitates a language designer to introduce composite concepts as separate conceptual and notational elements in a modelling language. Composite concepts are compositions of existing concepts. To facilitate the

  6. Erosion-resistant composite material

    Science.gov (United States)

    Finch, C.B.; Tennery, V.J.; Curlee, R.M.

    A highly erosion-resistant composite material is formed of chemical vapor-deposited titanium diboride on a sintered titanium diboride-nickel substrate. This material may be suitable for use in cutting tools, coal liquefaction systems, etc.

  7. Current voltage characteristics of composite superconductors with high contact resistance

    International Nuclear Information System (INIS)

    Akhmetov, A.A.; Baev, V.P.

    1984-01-01

    An experimental study has been made of current-voltage characteristics of composite superconductors with contact resistance between superconducting filaments and normal metal with high electrical conductivity. It is shown that stable resistive states exist in such conductors over a wide range of currents. The presence of resistive states is interpreted in terms of the resistive domain concept. The minimum and maximum currents of resistive states are found to be dependent on the electrical resistance of normal metal and magnetic field. (author)

  8. Using the concept of pseudo amino acid composition to predict resistance gene against Xanthomonas oryzae pv. oryzae in rice: an approach from chaos games representation.

    Science.gov (United States)

    Jingbo, Xia; Silan, Zhang; Feng, Shi; Huijuan, Xiong; Xuehai, Hu; Xiaohui, Niu; Zhi, Li

    2011-09-07

    To evaluate the possibility of an unknown protein to be a resistant gene against Xanthomonas oryzae pv. oryzae, a different mode of pseudo amino acid composition (PseAAC) is proposed to formulate the protein samples by integrating the amino acid composition, as well as the Chaos games representation (CGR) method. Some numerical comparisons of triangle, quadrangle and 12-vertex polygon CGR are carried to evaluate the efficiency of using these fractal figures in classifiers. The numerical results show that among the three polygon methods, triangle method owns a good fractal visualization and performs the best in the classifier construction. By using triangle + 12-vertex polygon CGR as the mathematical feature, the classifier achieves 98.13% in Jackknife test and MCC achieves 0.8462. Copyright © 2011 Elsevier Ltd. All rights reserved.

  9. Service composition: concepts, techniques, tools and trends

    NARCIS (Netherlands)

    Benatallah, B.; Dijkman, R.M.; Dumas, M.; Maamar, Z.; Stojanovic, Z.; Dahanayake, A.

    2005-01-01

    This chapter provides an overview of the area of service composition. It does so byintroducing a generic architecture for service composition and using this architecture todiscuss some salient concepts and techniques. The architecture is also used as aframework for providing a critical view into a

  10. High temperature resistant cermet and ceramic compositions

    Science.gov (United States)

    Phillips, W. M. (Inventor)

    1978-01-01

    Cermet compositions having high temperature oxidation resistance, high hardness and high abrasion and wear resistance, and particularly adapted for production of high temperature resistant cermet insulator bodies are presented. The compositions are comprised of a sintered body of particles of a high temperature resistant metal or metal alloy, preferably molybdenum or tungsten particles, dispersed in and bonded to a solid solution formed of aluminum oxide and silicon nitride, and particularly a ternary solid solution formed of a mixture of aluminum oxide, silicon nitride and aluminum nitride. Also disclosed are novel ceramic compositions comprising a sintered solid solution of aluminum oxide, silicon nitride and aluminum nitride.

  11. High temperature oxidation resistant cermet compositions

    Science.gov (United States)

    Phillips, W. M. (Inventor)

    1976-01-01

    Cermet compositions are designed to provide high temperature resistant refractory coatings on stainless steel or molybdenum substrates. A ceramic mixture of chromium oxide and aluminum oxide form a coating of chromium oxide as an oxidation barrier around the metal particles, to provide oxidation resistance for the metal particles.

  12. Influence of resistive matrices on the stability of superconducting composites

    International Nuclear Information System (INIS)

    Maccioni, P.

    1990-03-01

    Stability of superconducting composites is governed by limiting the temperature rise in conductors submitted to disturbances. Cooling exchange enhancement and reduction of the composite mean resistivity in the normal state, introducing a sufficient amount of copper, are the main ways to ensure stabilization. Nevertheless some losses occur in composites exposed to time varying fields because of induced currents between the filaments and circulating through the matrix. These currents have to be reduced to a convenient level by increasing the matrix resistivity by means of resistive barriers of greater resistivity than copper. It is necessary to study how the existence of these barriers affects the composite stability and whether an improved arrangement may lead to the fulfillment of the required conditions e.g: stability and low losses. The original theoretical approaches allow some existing models to be completed, to evaluate additional energy dissipation, inherent in current transfer through resistive barriers, and to compare the performance of two different conductor concepts from the cryostability point of view. Numerical simulations -performed by means of a finite element code- are in quite good agreement with theoretical predictions and link up with experimental results. The influence of resistive matrix and barriers on stability degradation is clearly demonstrated by the comparison between various kinds of conductors [fr

  13. Resistance gene management: concepts and practice

    Science.gov (United States)

    Christopher C. Mundt

    2012-01-01

    There is now a very long history of genetics/breeding for disease resistance in annual crops. These efforts have resulted in conceptual advances and frustrations, as well as practical successes and failures. This talk will review this history and its relevance to the genetics of resistance in forest species. All plant breeders and pathologists are familiar with boom-...

  14. Advanced composites structural concepts and materials technologies for primary aircraft structures: Design/manufacturing concept assessment

    Science.gov (United States)

    Chu, Robert L.; Bayha, Tom D.; Davis, HU; Ingram, J. ED; Shukla, Jay G.

    1992-01-01

    Composite Wing and Fuselage Structural Design/Manufacturing Concepts have been developed and evaluated. Trade studies were performed to determine how well the concepts satisfy the program goals of 25 percent cost savings, 40 percent weight savings with aircraft resizing, and 50 percent part count reduction as compared to the aluminum Lockheed L-1011 baseline. The concepts developed using emerging technologies such as large scale resin transfer molding (RTM), automatic tow placed (ATP), braiding, out-of-autoclave and automated manufacturing processes for both thermoset and thermoplastic materials were evaluated for possible application in the design concepts. Trade studies were used to determine which concepts carry into the detailed design development subtask.

  15. Shock resistance of composite material pipes

    International Nuclear Information System (INIS)

    Pays, M.F.

    1995-01-01

    Composite materials have found a wide range of applications for EDF nuclear plants. Applications include fire pipework, demineralized water, service water, and emergency-supplied service water piping. Some of those pipework is classified nuclear safety, their integrity (resistance to water aging and earthquakes or accidental excess pressure (water hammer)) must be safeguarded. As composite materials generally suffer damage for low energy impacts (under 10 J), the pipes planned for the Civaux power plant have been studied for their resistance to a low speed shock (0 to 50 m/s) and of a 0 to 110 J energy level. For three representative diameters (20, 150, 600 mm), the minimum impact energy that leads to a leak has been determined to be respectively 18, 20 and 48 J. Then the leak rate versus impact energy was plotted; until roughly 90 J, the leak rate remains stable at less than 25 cm 3 /h and raises to higher values (300 cm 3 /h) afterwards. The level of leakage in the range of impact energy tested always stays within the limits set by the Safety Authorities for metallic pipes. These results have been linked to destructive examinations, to clarify the damage mechanisms. Other tests are still ongoing to follow the evolution of the damage and of the leak rate while the pipe is maintained under service pressure during one year

  16. Soft shell hard core concept for aircraft impact resistant design

    International Nuclear Information System (INIS)

    Chen, C.; Rieck, P.J.

    1978-01-01

    For nuclear power plants sited in the vicinity of airports, the hypothetical events of aircraft impact have to be designed for. The conventional design concept is to strengthen the exterior structure to resist the impact induced force. The stiffened structures have two (2) disadvantages; one is the high construction cost, and the other is the high reaction force induced as well as the vibrational effects on the interior equipment and piping systems. This new soft shell hard core concept can relieve the above shortcomings. In this concept, the essential equipment required for safety are installed inside the hard core area for protection and the non-essential equipment are maintained between the hard core and soft shell area. During a hypothetical impact event, the soft shell will collapse locally and absorb large amounts of kinetic energy; hence, it reduces the reaction force and the vibrational effects. The design and analysis of the soft shell concept are discussed. (Author)

  17. Fracture resistance curves and toughening mechanisms in polymer based dental composites

    DEFF Research Database (Denmark)

    De Souza, J.A.; Goutianos, Stergios; Skovgaard, M.

    2011-01-01

    The fracture resistance (R-curve behaviour) of two commercial dental composites (Filtek Z350® and Concept Advanced®) were studied using Double Cantilever Beam sandwich specimens loaded with pure bending moments to obtain stable crack growth. The experiments were conducted in an environmental...... significantly higher fracture resistance than the composite with the coarser microstructure. The fracture properties were related to the flexural strength of the dental composites. The method, thus, can provide useful insight into how the microstructure enhances toughness, which is necessary for the future...

  18. Improving subcritical crack growth resistance for alumina glass dental composite

    NARCIS (Netherlands)

    Zhu, Q.; With, de G.

    2005-01-01

    The improvement of subcritical crack growth (SCG) resistance for alumina glass dental composites was explored in this study. The addition of nitrogen to the glass phases in the composite was found to increase the SCG resistance, where the SCG exponent n increases from 22 for the oxide glass

  19. Flame-Resistant Composite Materials For Structural Members

    Science.gov (United States)

    Spears, Richard K.

    1995-01-01

    Matrix-fiber composite materials developed for structural members occasionally exposed to hot, corrosive gases. Integral ceramic fabric surface layer essential for resistance to flames and chemicals. Endures high temperature, impedes flame from penetrating to interior, inhibits diffusion of oxygen to interior where it degrades matrix resin, resists attack by chemicals, helps resist erosion, and provides additional strength. In original intended application, composite members replace steel structural members of rocket-launching structures that deteriorate under combined influences of atmosphere, spilled propellants, and rocket exhaust. Composites also attractive for other applications in which corrosion- and fire-resistant structural members needed.

  20. Development of radiation resistant organic composites for cryogenic use

    International Nuclear Information System (INIS)

    Nishijima, S.

    1997-01-01

    The mechanism of the radiation induced degradation of the mechanical properties in composite materials have been studied and based on the mechanism the radiation resistant organic composites for fusion magnet have been developing. It was found that the degradation was brought by the change of the fracture mode from tensile (or flexural) to shear failure. Consequently the intrinsic parameter which control the degradation was concluded to be the interlaminar shear strength. To develop the radiation resistant composites, therefore, means to develop the composites showing the radiation resistant interlaminar shear strength. The mechanism was confirmed using three dimensional fabric reinforced plastics which do not have the interlaminar area. The roles of matrix in the composites were also revealed. The effects of dose quality and irradiated temperature on the radiation induced degradation were also discussed and the selection standards of the components for radiation resistant composites were proposed

  1. Composite Structure Modeling and Analysis of Advanced Aircraft Fuselage Concepts

    Science.gov (United States)

    Mukhopadhyay, Vivek; Sorokach, Michael R.

    2015-01-01

    NASA Environmentally Responsible Aviation (ERA) project and the Boeing Company are collabrating to advance the unitized damage arresting composite airframe technology with application to the Hybrid-Wing-Body (HWB) aircraft. The testing of a HWB fuselage section with Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) construction is presently being conducted at NASA Langley. Based on lessons learned from previous HWB structural design studies, improved finite-element models (FEM) of the HWB multi-bay and bulkhead assembly are developed to evaluate the performance of the PRSEUS construction. In order to assess the comparative weight reduction benefits of the PRSEUS technology, conventional cylindrical skin-stringer-frame models of a cylindrical and a double-bubble section fuselage concepts are developed. Stress analysis with design cabin-pressure load and scenario based case studies are conducted for design improvement in each case. Alternate analysis with stitched composite hat-stringers and C-frames are also presented, in addition to the foam-core sandwich frame and pultruded rod-stringer construction. The FEM structural stress, strain and weights are computed and compared for relative weight/strength benefit assessment. The structural analysis and specific weight comparison of these stitched composite advanced aircraft fuselage concepts demonstrated that the pressurized HWB fuselage section assembly can be structurally as efficient as the conventional cylindrical fuselage section with composite stringer-frame and PRSEUS construction, and significantly better than the conventional aluminum construction and the double-bubble section concept.

  2. Concept of a Conducting Composite Material for Lightning Strike Protection

    OpenAIRE

    Katunin A.; Krukiewicz K.; Herega A.; Catalanotti G.

    2016-01-01

    The paper focuses on development of a multifunctional material which allows conducting of electrical current and simultaneously holds mechanical properties of a polymeric composite. Such material could be applied for exterior fuselage elements of an aircraft in order to minimize damage occurring during lightning strikes. The concept introduced in this paper is presented from the points of view of various scientific disciplines including materials science, chemistry, structural physics and mec...

  3. High temperature resistant cermet and ceramic compositions. [for thermal resistant insulators and refractory coatings

    Science.gov (United States)

    Phillips, W. M. (Inventor)

    1978-01-01

    High temperature oxidation resistance, high hardness and high abrasion and wear resistance are properties of cermet compositions particularly to provide high temperature resistant refractory coatings on metal substrates, for use as electrical insulation seals for thermionic converters. The compositions comprise a sintered body of particles of a high temperature resistant metal or metal alloy, preferably molybdenum or tungsten particles, dispersed in and bonded to a solid solution formed of aluminum oxide and silicon nitride, and particularly a ternary solid solution formed of a mixture of aluminum oxide, silicon nitride and aluminum nitride. Ceramic compositions comprising a sintered solid solution of aluminum oxide, silicon nitride and aluminum nitride are also described.

  4. Study on the heat-resistant EB curing composites

    International Nuclear Information System (INIS)

    Bao Jianwen; Li Yang; Li Fengmei

    2000-01-01

    There are many advantages in the EB-curing process of composites. Heat-resistant EB-curing composites could substitute for polyimide composites used in aeronautical engine. The effects of catalyst and dose on the cured resin were investigated. The heat-resistance of the resin cured by EB was evaluated by dynamic mechanical thermal analysis (DMTA). The experiment result shows that the mechanical property of the composites cured by EB could meet the needs of the aeronautical engine in 250degC. (author)

  5. Effect of composition on the polarization and ohmic resistances of ...

    Indian Academy of Sciences (India)

    2017-06-09

    Jun 9, 2017 ... Solid oxide fuel cell; composite cathodes; polarization resistance; ohmic resistance; ... of Oad on LSM, (iii) conversion of Oad into oxygen ion ... ions need to flow through the low temperature sintered ..... TPB's are present) suggest the formation of face-to-face con- ..... calculated using the following equation.

  6. Design and Analysis of a Stiffened Composite Structure Repair Concept

    Science.gov (United States)

    Przekop, Adam

    2011-01-01

    A design and analysis of a repair concept applicable to a stiffened thin-skin composite panel based on the Pultruded Rod Stitched Efficient Unitized Structure is presented. Since the repair concept is a bolted repair using metal components, it can easily be applied in the operational environment. Initial analyses are aimed at validating the finite element modeling approach by comparing with available test data. Once confidence in the analysis approach is established several repair configurations are explored and the most efficient one presented. Repairs involving damage to the top of the stiffener alone are considered in addition to repairs involving a damaged stiffener, flange and underlying skin. High fidelity finite element modeling techniques such as mesh-independent definition of compliant fasteners, elastic-plastic metallic material properties and geometrically nonlinear analysis are utilized in the effort. The results of the analysis are presented and factors influencing the design are assessed and discussed.

  7. Investigation on low velocity impact resistance of SMA composite material

    Science.gov (United States)

    Hu, Dianyin; Zhang, Long; Wang, Rongqiao; Zhang, Xiaoyong

    2016-04-01

    A method to improve low velocity impact resistance of aeroengine composite casing using shape memory alloy's properties of shape memory(SM) and super-elasticity(SE) is proposed in this study. Firstly, a numerical modeling of SMA reinforced composite laminate under low velocity impact load with impact velocity of 10 m/s is established based on its constitutive model implemented by the VUMAT subroutine of commercial software ABAQUS. Secondly, the responses of SMA composite laminate including stress and deflection distributions were achieved through transient analysis under low velocity impact load. Numerical results show that both peak stress and deflection values of SMA composite laminate are less than that without SMA, which proves that embedding SMA into the composite structure can effectively improve the low velocity impact performance of composite structure. Finally, the influence of SM and SE on low velocity impact resistance is quantitatively investigated. The values of peak stress and deflection of SMA composite based on SM property decrease by 18.28% and 9.43% respectively, compared with those without SMA, instead of 12.87% and 5.19% based on SE. In conclusion, this proposed model described the impact damage of SMA composite structure and turned to be a more beneficial method to enhance the impact resistance by utilizing SM effect.

  8. Design Concepts for Cooled Ceramic Composite Turbine Vane

    Science.gov (United States)

    Boyle, Robert J.; Parikh, Ankur H.; Nagpal, VInod K.

    2015-01-01

    The objective of this work was to develop design concepts for a cooled ceramic vane to be used in the first stage of the High Pressure Turbine(HPT). To insure that the design concepts were relevant to the gas turbine industry needs, Honeywell International Inc. was subcontracted to provide technical guidance for this work. The work performed under this contract can be divided into three broad categories. The first was an analysis of the cycle benefits arising from the higher temperature capability of Ceramic Matrix Composite(CMC) compared with conventional metallic vane materials. The second category was a series of structural analyses for variations in the internal configuration of first stage vane for the High Pressure Turbine(HPT) of a CF6 class commercial airline engine. The third category was analysis for a radial cooled turbine vanes for use in turboshaft engine applications. The size, shape and internal configuration of the turboshaft engine vanes were selected to investigate a cooling concept appropriate to small CMC vanes.

  9. Irradiatable polymer composition with improved oxidation resistance

    International Nuclear Information System (INIS)

    Lyons, B.J.

    1977-01-01

    A method is described for the incorporation of a substantially insoluble organic phosphite into a polymer composition such as polyolefin polymers or ethylene copolymers to prevent oxidation of the polymer at elevated temperatures after radiation-induced crosslinking. The crosslinking is readily achieved without affecting the antioxidant properties of the organic phosphite. Particularly suitable organic compounds are derivatives of pentaerythritol, dipentaerythritol, and tripentaerythritol in cooncentrations of 1 to 3% of the mixture to be irradiated

  10. Wear and impact resistance of HVOF sprayedceramic matrix composites coating

    Science.gov (United States)

    Prawara, B.; Martides, E.; Priyono, B.; Ardy, H.; Rikardo, N.

    2016-02-01

    Ceramic coating has the mechanical properties of high hardness and it is well known for application on wear resistance, but on the other hand the resistance to impact load is low. Therefore its use is limited to applications that have no impact loading. The aim of this research was to obtain ceramic-metallic composite coating which has improved impact resistance compared to conventional ceramic coating. The high impact resistance of ceramic-metallic composite coating is obtained from dispersed metallic alloy phase in ceramic matrix. Ceramic Matrix Composites (CMC) powder with chrome carbide (Cr3C2) base and ceramic-metal NiAl-Al2O3 with various particle sizes as reinforced particle was deposited on mild steel substrate with High Velocity Oxygen Fuel (HVOF) thermal spray coating. Repeated impact test showed that reinforced metallic phase size influenced impact resistance of CMC coating. The ability of CMC coating to absorb impact energy has improved eight times and ten times compared with original Cr3C2 and hard chrome plating respectively. On the other hand the high temperature corrosion resistance of CMC coating showed up to 31 cycles of heating at 800°C and water quenching cooling.

  11. Common bunt resistant wheat composite cross populations

    DEFF Research Database (Denmark)

    Steffan, Philipp Matthias; Borgen, A.; Backes, Gunter Martin

    stability. However, a number of challenges must be met before diverse wheat populations can be introduced into commercial wheat production: one of these is the development of breeding technologies based on mass selection which enable breeders and farmers to improve specific traits in populations...... and maintain diversity at the same time. BIOBREED is a project which commenced in Denmark in 2011 to meet these challenges for wheat population breeding. The project focuses on the development of tools and methods for mass selection of traits relevant for organic and low input production, where it is expected...... that the highest benefits of utilizing diverse populations can be achieved. BIOBREED focuses on three main aspects of wheat population breeding for organic and low input production systems: i) common bunt (caused by Tilletia caries) resistance, ii) selection for improved protein content and iii) the influence...

  12. Model for the resistive critical current transition in composite superconductors

    International Nuclear Information System (INIS)

    Warnes, W.H.

    1988-01-01

    Much of the research investigating technological type-II superconducting composites relies on the measurement of the resistive critical current transition. We have developed a model for the resistive transition which improves on older models by allowing for the very different nature of monofilamentary and multifilamentary composite structures. The monofilamentary model allows for axial current flow around critical current weak links in the superconducting filament. The multifilamentary model incorporates an additional radial current transfer between neighboring filaments. The development of both models is presented. It is shown that the models are useful for extracting more information from the experimental data than was formerly possible. Specific information obtainable from the experimental voltage-current characteristic includes the distribution of critical currents in the composite, the average critical current of the distribution, the range of critical currents in the composite, the field and temperature dependence of the distribution, and the fraction of the composite dissipating energy in flux flow at any current. This additional information about the distribution of critical currents may be helpful in leading toward a better understanding of flux pinning in technological superconductors. Comparison of the models with several experiments is given and shown to be in reasonable agreement. Implications of the models for the measurement of critical currents in technological composites is presented and discussed with reference to basic flux pinning studies in such composites

  13. Laboratory tests on fungal resistance of wood filled polyethylene composites

    Science.gov (United States)

    Craig M. Clemons; Rebecca E. Ibach

    2002-01-01

    A standard method for determining the durability of structural wood was modified for testing the fungal resistance of composites made from high density polyethylene filled with 50% wood flour. Moisture content, mechanical properties, and weight loss were measured over 12 weeks exposure to brown-and white-rot fungi. Mechanical properties were decreased, but irreversible...

  14. Radiation resistant organic composites for superconducting fusion magnets

    International Nuclear Information System (INIS)

    Nishijima, S.; Okada, T.

    1993-01-01

    Organic composite materials (usually reinforced by glas fibers: GFRP) are to be used in fusion superconducting magnets as insulating and/or structural materials. The fusion superconducting magnets are operated under radiation environments and hence the radiation induced degradation of magnet components is ought to be estimated. Among the components the organic composite materials were evaluated to be the most radiation sensitive. Consequently the development of radiation resistant organic composite materials is thought one of the 'key' technologies for fusion superconducting magnets. The mechanism of radiation-induced degradation was studied and the degradation of interlaminar shear strength (ILSS) was found to be the intrinsic phenomenon which controlled the overall degradation of organic composite materials. The degradation of ILSS was studied changing matrix resin, reinforcement and type of fabrics. The possible combination of the organic composites for the fusion superconducting magnet will be discussed. (orig.)

  15. Electrodeposition and Corrosion Resistance of Ni-Graphene Composite Coatings

    Science.gov (United States)

    Szeptycka, Benigna; Gajewska-Midzialek, Anna; Babul, Tomasz

    2016-08-01

    The research on the graphene application for the electrodeposition of nickel composite coatings was conducted. The study assessed an important role of graphene in an increased corrosion resistance of these coatings. Watts-type nickel plating bath with low concentration of nickel ions, organic addition agents, and graphene as dispersed particles were used for deposition of the composite coatings nickel-graphene. The results of investigations of composite coatings nickel-graphene deposited from the bath containing 0.33, 0.5, and 1 g/dm3 graphene and one surface-active substance were shown. The contents of particles in coatings, the surface morphology, the cross-sectional structures of the coated samples, and their thickness and the internal stresses were studied. Voltammetric method was used for examination of the corrosion resistance of samples of composite coatings in 0.5 M NaCl. The obtained results suggest that the content of incorporated graphene particles increases with an increasing amount of graphene in plating bath. The application of organic compounds was advantageous because it caused compressive stresses in the deposited coatings. All of the nickel-graphene composite layers had better corrosion resistance than the nickel coating.

  16. Using the adaptive SMA composite cylinder concept to reduce radial dilation in composite pressure vessels

    Science.gov (United States)

    Paine, Jeffrey S.; Rogers, Craig A.

    1995-05-01

    Composite materials are widely used in the design of pressurized gas and fluid vessels for applications ranging from underground gasoline storage tanks to rocket motors for the space shuttle. In the design of a high pressure composite vessel (Pi > 12 Ksi), thick-wall (R/h short term dilation and long term creep are not problematic for applications requiring only the containment of the pressurized fluid. In applications where metallic liners are required, however, substantial dilation and creep causes plastic yielding which leads to reduced fatigue life. To applications such as a hydraulic accumulator, where a piston is employed to fit and seal the fluid in the composite cylinder, the dilation and creep may allow leakage and pressure loss around the piston. A concept called the adaptive composite cylinder is experimentally presented. Shape memory alloy wire in epoxy resin is wrapped around or within polymer matrix composite cylinders to reduce radial dilation of the cylinder. Experimental results are presented that demonstrate the ability of the SMA wire layers to reduce radial dilation. Results from experimental testing of the recovery stress fatigue response of nitinol shape memory alloy wires is also presented.

  17. Wear resistance and fracture mechanics of WC-Co composites

    International Nuclear Information System (INIS)

    Kaytbay, Saleh; El-Hadek, Medhat

    2014-01-01

    Manufacturing of WC-Co composites using the electroless precipitation method at different sintering temperatures of 1 100, 1 250, 1 350 and 1 500 C was successfully achieved. The chemical composition of the investigated materials was 90 wt.% WC with 10 wt.% Co, and 80 wt.% WC with 20 wt.% Co. The specific density, densification, and Vickers microhardness measurements were found to increase with increased sintering temperature for both the WC-Co compositions. The composites of tungsten carbide with 10 wt.% Co had a higher specific density and Vickers microhardness measurements than those for the composites of tungsten carbide with 20 wt.% Co. Composites with WC-10 wt.% Co had better wear resistance. The stress-strain and transverse rupture strength increased monotonically with the increase in sintering temperatures, agreeing with the material hardness and wear resistance behavior. Fractographical scanning electron microscopy analysis of the fracture surface demonstrated a rough characteristic conical shape failure in the direction of the maximum shear stress. A proposed mechanism for the formation of the conical fracture surface under compression testing is presented. (orig.)

  18. Shape memory-based tunable resistivity of polymer composites

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Hongsheng, E-mail: hongshengluo@163.com [Faculty of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006 (China); Zhou, Xingdong; Ma, Yuanyuan [Faculty of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006 (China); Yi, Guobin, E-mail: ygb116@163.com [Faculty of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006 (China); Cheng, Xiaoling [Faculty of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006 (China); Zhu, Yong [Shanghai Hiend Polyurethane Inc., No. 389, Jinshan District, Shanghai (China); Zu, Xihong; Zhang, Nanjun; Huang, Binghao; Yu, Lifang [Faculty of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006 (China)

    2016-02-15

    Graphical abstract: Hybrid nanofillers of the CNTs and AgNPs were embedded into a shape memory polyurethane. The composites exhibited tunable conduction, which could be facially tailored by the compositions and the thermal–mechanical programming. - Highlights: • Electrically conductive polymer composites in bi-layer structure were fabricated. • The CNTs/AgNPs layer had influence on the mechanics and thermal transitions. • The conductivity could be facially tailored via a thermo-mechanical programming. • The AgNPs contents enlarged the gauge factor of the resistivity–strain curves. • Tunneling theory was suitable for simulating the strain-dependent behaviors. - Abstract: A conductive composite in bi-layer structure was fabricated by embedding hybrid nanofillers, namely carbon nanotubes (CNTs) and silver nanoparticles (AgNPs), into a shape memory polyurethane (SMPU). The CNT/AgNP-SMPU composites exhibited a novel tunable conductivity which could be facially tailored in wide range via the compositions or a specifically designed thermo-mechanical shape memory programming. The morphologies of the conductive fillers and the composites were investigated by scanning electron microscope (SEM). The mechanical and thermal measurements were performed by tensile tests and differential scanning calorimetry (DSC). By virtue of a specifically explored shape memory programming, the composites were stretched and fixed into different temporary states. The electrical resistivity (R{sub s}) varied accordingly, which was able to be stabilized along with the shape fixing. Theoretical prediction based upon the tunneling model was performed. The R{sub s}–strain curves of the composites with different compositions were well fitted. Furthermore, the relative resistivity and the Gauge factor along with the elongation were calculated. The influence of the compositions on the strain-dependent R{sub s} was disclosed. The findings provided a new avenue to tailor the conductivity

  19. Thermal Oxidation Resistance of Rare Earth-Containing Composite Elastomer

    Institute of Scientific and Technical Information of China (English)

    邱关明; 张明; 周兰香; 中北里志; 井上真一; 冈本弘

    2001-01-01

    The rare earth-containing composite elastomer was obtained by the reaction of vinyl pyridine-SBR (PSBR) latex with rare earth alkoxides, and its thermal oxidation resistance was studied. After aging test, it is found that its retention rate of mechanical properties is far higher than that of the control sample. The results of thermogravimetric analysis show that its thermal-decomposing temperature rises largely. The analysis of oxidation mechanisms indicates that the main reasons for thermal oxidation resistance are that rare earth elements are of the utility to discontinue autoxidation chain reaction and that the formed complex structure has steric hindrance effect on oxidation.

  20. Oxidation resistance coating for niobium base structural composites

    International Nuclear Information System (INIS)

    Tabaru, T.; Shobu, K.; Kim, J.H.; Hirai, H.; Hanada, S.

    2003-01-01

    Oxidation behavior of Al-rich Mo(Si,Al) 2 base alloys, which is a candidate material for the oxidation resistance coating on Nb base structural composites, were investigated by thermogravimetry. The Mo(Si,Al) 2 base alloys containing Mo 5 (Si,Al) 3 up to about 10 vol% exhibits excellent oxidation resistance at temperatures ranging from 780 to 1580 K, particularly at 1580 K due to continuous Al 2 O 3 layer development. To evaluate the applicability of the Mo(Si,Al) 2 base coating, plasma spraying on Nb base composites were undertaken. However, interface reaction layer was found to form during the following heat treatment. Preparation of Mo(Si,Al) 2 /Al 2 O 3 /Nb layered structures via powder metallurgical process was attempted to preclude diffusion reaction between coating and substrate. (orig.)

  1. Affirmation, Validation, and Empowerment: Influences of a Composition Competition on Students' Self-Concepts as Musicians

    Science.gov (United States)

    Albert, Daniel J.

    2017-01-01

    The purpose of this study was to determine if participation in a composition competition influenced four K-12 students' self-concepts as musicians. Research questions explored motivations for these four students to enter into a composition competition, influences of the competition on students' self-concepts as musicians (if at all), and effects…

  2. Fissure sealant materials: Wear resistance of flowable composite resins.

    Science.gov (United States)

    Asefi, Sohrab; Eskandarion, Solmaz; Hamidiaval, Shadi

    2016-01-01

    Background. Wear resistance of pit and fissure sealant materials can influence their retention. Wear characteristics of sealant materials may determine scheduling of check-up visits. The aim of this study was to compare wear resistance of two flowable composite resins with that of posterior composite resin materials. Methods. Thirty-five disk-shaped specimens were prepared in 5 groups, including two flowable composite resins (Estelite Flow Quick and Estelite Flow Quick High Flow), Filtek P90 and Filtek P60 and Tetric N-Ceram. The disk-shaped samples were prepared in 25-mm diameter by packing them into a two-piece aluminum mold and then light-cured. All the specimens were polished for 1minute using 600-grit sand paper. The samples were stored in distilled water at room temperature for 1 week and then worn by two-body abrasion test using "pin-on-disk" method (with distilled water under a 15-Nload at 0.05 m/s, for a distance of 100 meter with Steatite ceramic balls antagonists). A Profilometer was used for evaluating the surface wear. Data were analyzed with the one-way ANOVA. Results. Estelite Flow Quick exhibited 2708.9 ± 578.1 μm(2) and Estelite Flow Quick High Flow exhibited 3206 ± 2445.1 μm(2)of wear but there were no significant differences between the groups. They demonstrated similar wear properties. Conclusion. Estelite flowable composite resins have wear resistance similar to nano- and micro-filled and micro-hybrid composite resins. Therefore, they can be recommended as pit and fissure sealant materials in the posterior region with appropriate mechanical characteristics.

  3. Wear resistance of polypropylene-SiC composite

    Science.gov (United States)

    Abenojar, J.; Enciso, B.; Martínez, MA; Velasco, F.

    2017-05-01

    In this work, the wear resistance of thermoplastic composites with a high amount of ceramic is evaluated. Composites made of polypropylene (PP) and silicon carbide (SiC) powder at 50 wt% were used with the final objective of manufacturing ablative materials. This is the first part of a project studying the wear resistance and the mechanical properties of those composites, to be used in applications like habitat industry. In theory, the exposure to high temperature of ablative materials involves the elimination of thermal energy by the sacrifice of surface polymer. In our case, PP will act as a heat sink, up to the reaction temperature (melting or sublimation), where endothermic chemical decomposition into charred material and gaseous products occurs. As the surface is eroded, it is formed a SiC like-foam with improved insulation performance. Composites were produced by extrusion and hot compression. The wear characterization was performed by pin-on-disk test. Wear test was carried out under standard ASTM G99. The parameters were 120 rpm speed, 15 N load, a alumina ball with 6 mm as pin and 1000 m sliding distance. The tracks were also observed by opto-digital microscope.

  4. Wear resistance of polypropylene-SiC composite

    International Nuclear Information System (INIS)

    Abenojar, J; Enciso, B; Martínez, MA; Velasco, F

    2017-01-01

    In this work, the wear resistance of thermoplastic composites with a high amount of ceramic is evaluated. Composites made of polypropylene (PP) and silicon carbide (SiC) powder at 50 wt% were used with the final objective of manufacturing ablative materials. This is the first part of a project studying the wear resistance and the mechanical properties of those composites, to be used in applications like habitat industry. In theory, the exposure to high temperature of ablative materials involves the elimination of thermal energy by the sacrifice of surface polymer. In our case, PP will act as a heat sink, up to the reaction temperature (melting or sublimation), where endothermic chemical decomposition into charred material and gaseous products occurs. As the surface is eroded, it is formed a SiC like-foam with improved insulation performance. Composites were produced by extrusion and hot compression. The wear characterization was performed by pin-on-disk test. Wear test was carried out under standard ASTM G99. The parameters were 120 rpm speed, 15 N load, a alumina ball with 6 mm as pin and 1000 m sliding distance. The tracks were also observed by opto-digital microscope. (paper)

  5. Fabrication of an Electrically-Resistive, Varistor-Polymer Composite

    Directory of Open Access Journals (Sweden)

    Sanaz A. Mohammadi

    2012-11-01

    Full Text Available This study focuses on the fabrication and electrical characterization of a polymer composite based on nano-sized varistor powder. The polymer composite was fabricated by the melt-blending method. The developed nano-composite was characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, field emission scanning electron microscopy (FeSEM, and energy-dispersive X-ray spectroscopy (EDAX. The XRD pattern revealed the crystallinity of the composite. The XRD study also showed the presence of secondary phases due to the substitution of zinc by other cations, such as bismuth and manganese. The TEM picture of the sample revealed the distribution of the spherical, nano-sized, filler particles throughout the matrix, which were in the 10–50 nm range with an average of approximately 11 nm. The presence of a bismuth-rich phase and a ZnO matrix phase in the ZnO-based varistor powder was confirmed by FeSEM images and EDX spectra. From the current-voltage curves, the non-linear coefficient of the varistor polymer composite with 70 wt% of nano filler was 3.57, and its electrical resistivity after the onset point was 861 KΩ. The non-linear coefficient was 1.11 in the sample with 100 wt% polymer content. Thus, it was concluded that the composites established a better electrical non-linearity at higher filler amounts due to the nano-metric structure and closer particle linkages.

  6. Current concepts in the management of resistant hypertension: a ...

    African Journals Online (AJOL)

    Background: Resistant hypertension is defined as uncontrolled hypertension above the target goal despite treatment with 3 or more antihypertensive agents, one of which is a diuretic, at optimum and best tolerated doses. The target blood pressure is defined as < 140/90 mmHg in most people and < 130/80 mmHg in those ...

  7. Treatment resistance and psychodynamic psychiatry: concepts psychiatry needs from psychoanalysis.

    Science.gov (United States)

    Plakun, Eric

    2012-06-01

    Over the last 30 years psychiatry and psychoanalysis have moved in substantially divergent directions. Psychiatry has become rich in methodology but conceptually limited, with a drift toward biological reductionism. Psychoanalysis has remained relatively limited in methodology, but conceptually rich. The rich methodology of psychiatry has led to major contributions in discovering gene by environment interactions, the importance of early adversity, and to recognition of the serious problem posed by treatment resistance. However, psychiatry's biologically reductionistic conceptual focus interferes with the development of a nuanced clinical perspective based on emerging knowledge that might help more treatment resistant patients become treatment responders. This article argues that recognition of the problem of treatment resistance in psychiatry creates a need for it to reconnect with the conceptual richness of psychoanalysis in order to improve patient care. Psychodynamic psychiatry is defined as the relevant intersection of psychiatry and psychoanalysis where this reconnection can occur. I will suggest selected aspects of psychoanalysis that are especially relevant to psychiatry in improving outcomes in work with treatment resistant patients.

  8. Electrical Resistance Based Damage Modeling of Multifunctional Carbon Fiber Reinforced Polymer Matrix Composites

    Science.gov (United States)

    Hart, Robert James

    In the current thesis, the 4-probe electrical resistance of carbon fiber-reinforced polymer (CFRP) composites is utilized as a metric for sensing low-velocity impact damage. A robust method has been developed for recovering the directionally dependent electrical resistivities using an experimental line-type 4-probe resistance method. Next, the concept of effective conducting thickness was uniquely applied in the development of a brand new point-type 4-probe method for applications with electrically anisotropic materials. An extensive experimental study was completed to characterize the 4-probe electrical resistance of CFRP specimens using both the traditional line-type and new point-type methods. Leveraging the concept of effective conducting thickness, a novel method was developed for building 4-probe electrical finite element (FE) models in COMSOL. The electrical models were validated against experimental resistance measurements and the FE models demonstrated predictive capabilities when applied to CFRP specimens with varying thickness and layup. These new models demonstrated a significant improvement in accuracy compared to previous literature and could provide a framework for future advancements in FE modeling of electrically anisotropic materials. FE models were then developed in ABAQUS for evaluating the influence of prescribed localized damage on the 4-probe resistance. Experimental data was compiled on the impact response of various CFRP laminates, and was used in the development of quasi- static FE models for predicting presence of impact-induced delamination. The simulation-based delamination predictions were then integrated into the electrical FE models for the purpose of studying the influence of realistic damage patterns on electrical resistance. When the size of the delamination damage was moderate compared to the electrode spacing, the electrical resistance increased by less than 1% due to the delamination damage. However, for a specimen with large

  9. Design of a new bottom antireflective coating composition for KrF resist

    Science.gov (United States)

    Mizutani, Kazuyoshi; Momota, Makoto; Aoai, Toshiaki; Yagihara, Morio

    1999-06-01

    A study for a new organic bottom antireflective coating (BARC) composition is described. A structural design of a light-absorbing dye was most important because dye structure not only plays a role in eliminating reflection from a substrate but also shows influence on dry etch rate of BARC material to a considerable extent. For example, an anthracene moiety with large absorption at 248 nm had undesirable dry etch resistance. 3-Hydroxy-2-naphthoic acid moiety was found to be one of suitable dyes for KrF BARC compositions, and the polymer bearing the dye showed enough absorbance and good erodability in dry etch. The BARC polymer was eroded as one and a half times faster than a novolak resin, and a little faster than an anthracene incorporated polymer. The result was discussed from the concepts of Ohnishi parameter and the ring parameter for dry etch durability of resist materials. BARC polymer should be thermoset by hard bake to eliminate intermixing with resist compositions. The BARC polymer bearing hydroxy group which is useful for a crosslinking reaction was thermoset in the presence of melamine-formaldehyde crosslinker and an acid catalyst after baking over 200 degrees C.

  10. Metal-nanotube composites as radiation resistant materials

    Energy Technology Data Exchange (ETDEWEB)

    González, Rafael I.; Valencia, Felipe; Mella, José; Kiwi, Miguel, E-mail: m.kiwi.t@gmail.com [Departamento de Física, Facultad de Ciencias, CEDENNA, Universidad de Chile, Casilla 653, Santiago 7800024 (Chile); Duin, Adri C. T. van [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); So, Kang Pyo; Li, Ju [Department of Nuclear Science and Engineering and Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Bringa, Eduardo M. [CONICET and Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza 5500 (Argentina)

    2016-07-18

    The improvement of radiation resistance in nanocomposite materials is investigated by means of classical reactive molecular dynamics simulations. In particular, we study the influence of carbon nanotubes (CNTs) in an Ni matrix on the trapping and possible outgassing of He. When CNTs are defect-free, He atoms diffuse alongside CNT walls and, although there is He accumulation at the metal-CNT interface, no He trespassing of the CNT wall is observed, which is consistent with the lack of permeability of a perfect graphene sheet. However, when vacancies are introduced to mimic radiation-induced defects, He atoms penetrate CNTs, which play the role of nano-chimneys, allowing He atoms to escape the damaged zone and reduce bubble formation in the matrix. Consequently, composites made of CNTs inside metals are likely to display improved radiation resistance, particularly when radiation damage is related to swelling and He-induced embrittlement.

  11. Metal-nanotube composites as radiation resistant materials

    International Nuclear Information System (INIS)

    González, Rafael I.; Valencia, Felipe; Mella, José; Kiwi, Miguel; Duin, Adri C. T. van; So, Kang Pyo; Li, Ju; Bringa, Eduardo M.

    2016-01-01

    The improvement of radiation resistance in nanocomposite materials is investigated by means of classical reactive molecular dynamics simulations. In particular, we study the influence of carbon nanotubes (CNTs) in an Ni matrix on the trapping and possible outgassing of He. When CNTs are defect-free, He atoms diffuse alongside CNT walls and, although there is He accumulation at the metal-CNT interface, no He trespassing of the CNT wall is observed, which is consistent with the lack of permeability of a perfect graphene sheet. However, when vacancies are introduced to mimic radiation-induced defects, He atoms penetrate CNTs, which play the role of nano-chimneys, allowing He atoms to escape the damaged zone and reduce bubble formation in the matrix. Consequently, composites made of CNTs inside metals are likely to display improved radiation resistance, particularly when radiation damage is related to swelling and He-induced embrittlement.

  12. Method of making sulfur-resistant composite metal membranes

    Science.gov (United States)

    Way, J Douglas [Boulder, CO; Lusk, Mark [Golden, CO; Thoen, Paul [Littleton, CO

    2012-01-24

    The invention provides thin, hydrogen-permeable, sulfur-resistant membranes formed from palladium or palladium-alloy coatings on porous, ceramic or metal supports. Also disclosed are methods of making these membranes via sequential electroless plating techniques, wherein the method of making the membrane includes decomposing any organic ligands present on the substrate, reducing the palladium crystallites on the substrate to reduced palladium crystallites, depositing a film of palladium metal on the substrate and then depositing a second, gold film on the palladium film. These two metal films are then annealed at a temperature between about 200.degree. C. and about 1200.degree. C. to form a sulfur-resistant, composite PdAu alloy membrane.

  13. Maleimido substituted cyclotriphosphazene resins for fire and heat resistant composites

    Science.gov (United States)

    Kumar, D.; Fohlen, G. M.; Parker, J. A.

    1983-01-01

    A new class of fire- and heat-resistant matrix resins have been synthesized by the thermal polymerization of maleimido substituted phenoxycyclotriphosphazenes. The resins have exhibited a char yield of 82 percent at 800 C in nitrogen and 81 percent at 700 C in air. Graphite-fabric laminates based on a resin of this class have shown a limiting oxygen index of 100 percent even at 300 C. Details of the fabrication of the resins and the composites and testing procedures are discussed.

  14. Fracture resistance of teeth restored with packable and hybrid composites

    Directory of Open Access Journals (Sweden)

    Ghavam M

    2006-06-01

    Full Text Available Background and Aim: With recent introduction of packable composites, it is claimed that they apply less stress on tooth structure because of reduced polymerization shrinkage, and similarity of coefficient of thermal expansion to tooth structure. However, the high viscosity may in turn cause less adaptation, so it is not clearly known whether these materials strengthen tooth structure or not. The aim of this study was to evaluate fracture resistance of maxillary premolars, receiving hybrid or packable composite restorations with different methods of application and curing. Materials and Methods: In this experimental study, seventy five intact premolars were randomly assigned to five groups of 15 teeth each. One group was maintained intact as the control group. Similar MOD cavities were prepared in the other teeth. The teeth in group two were restored with Spectrum in incremental layers and light cured with 500 mw/cm2 intensity. The third group were filled with Surefil and cured with light intensity of 500 mw/cm2. The groups four and five were restored with Surefil in bulk technique with two different modes: 500 mw/cm2 intensity and a ramp mode (100-900 mw/cm2 respectively. After thermocycling, force to fracture was assessed and degree of conversion (DC at the bottom of cavities was evaluated for different modes and methods. The curing and placement methods in groups tested for DC (A to D were the same as fracture resistance groups (2 to 5. Data were analyzed using one way ANOVA and Tukey HSD tests with p<0.05 as the limit of significance. Results: All the restored groups showed significantly less fracture resistance than the control group, but had no significant difference among themselves. DC of Spectrum was higher than Surefil. Bulk method with 500 mw/cm2 light intensity, significantly decreased DC. DC in bulk method with high light intensity was not significantly different from incremental method with 500 mw/cm2 light intensity. Conclusion

  15. Laser cladding of wear resistant metal matrix composite coatings

    International Nuclear Information System (INIS)

    Yakovlev, A.; Bertrand, Ph.; Smurov, I.

    2004-01-01

    A number of coatings with wear-resistant properties as well as with a low friction coefficient are produced by laser cladding. The structure of these coatings is determined by required performance and realized as metal matrix composite (MMC), where solid lubricant serves as a ductile matrix (e.g. CuSn), reinforced by appropriate ceramic phase (e.g. WC/Co). One of the engineered coating with functionally graded material (FGM) structure has a dry friction coefficient 0.12. Coatings were produced by coaxial injection of powder blend into the zone of laser beam action. Metallographic and tribological examinations were carried out confirming the advanced performance of engineered coatings

  16. Effects of Siblings' Sex Composition on Self-Concept.

    Science.gov (United States)

    Nystul, Michael S.

    1981-01-01

    Subjects (N=106) from families of two or three children were analyzed in terms of various sibling sex configurations and administered the Tennessee Self Concept Scale. Results were discussed in terms of a "special place in the family." (Author/CM)

  17. [Concept Analysis for Psychological Insulin Resistance in Korean People with Diabetes].

    Science.gov (United States)

    Song, Youngshin

    2016-06-01

    The purpose of this study was to define the concept for psychological insulin resistance in the Korean population with diabetes. The Hybrid model was used to perform the concept analysis of psychological insulin resistance. Results from both the theoretical review with 26 studies and a field study including 19 participants with diabetes were included in final process. The preceding factors of psychological insulin resistance were uncontrolled blood glucose and change in daily life. The concept of psychological insulin resistance was found to have three categories with 8 attributes such as emotional factors (negative feeling), cognitive factors (low awareness and knowledge, low confidence for self-injection) and supportive factors (economic burden, dependency life, embarrassing, feeling about supporters, feeling of trust in, vs mistrust of health care providers). The 8 attributes included 30 indicators. The psychological insulin resistance of population with diabetes in Korea was defined as a complex phenomenon associated with insulin therapy that can be affected by emotional factors, cognitive factors, and supportive relational factors. Based on the results, a tool for measuring psychological insulin resistance of Koreans with diabetes and effective programs for enhancing insulin adherence should be developed in future studies.

  18. Aligned composite structures for mitigation of impact damage and resistance to wear in dynamic environments

    Science.gov (United States)

    Mulligan, Anthony C.; Rigali, Mark J.; Sutaria, Manish P.; Popovich, Dragan; Halloran, Joseph P.; Fulcher, Michael L.; Cook, Randy C.

    2009-04-14

    Fibrous monolith composites having architectures that provide increased flaw insensitivity, improved hardness, wear resistance and damage tolerance and methods of manufacture thereof are provided for use in dynamic environments to mitigate impact damage and increase wear resistance.

  19. Oxidation resistant coatings for ceramic matrix composite components

    Energy Technology Data Exchange (ETDEWEB)

    Vaubert, V.M.; Stinton, D.P. [Oak Ridge National Lab., TN (United States); Hirschfeld, D.A. [New Mexico Inst. of Mining and Technology, Socorro, NM (United States). Dept. of Materials and Metallurgical Engineering

    1998-11-01

    Corrosion resistant Ca{sub 0.6}Mg{sub 0.4}Zr{sub 4}(PO{sub 4}){sub 6} (CMZP) and Ca{sub 0.5}Sr{sub 0.5}Zr{sub 4}(PO{sub 4}){sub 6} (CS-50) coatings for fiber-reinforced SiC-matrix composite heat exchanger tubes have been developed. Aqueous slurries of both oxides were prepared with high solids loading. One coating process consisted of dipping the samples in a slip. A tape casting process has also been created that produced relatively thin and dense coatings covering a large area. A processing technique was developed, utilizing a pre-sintering step, which produced coatings with minimal cracking.

  20. Residual stress effects on the impact resistance and strength of fiber composites

    Science.gov (United States)

    Chamis, C. C.

    1973-01-01

    Equations have been derived to predict degradation effects of microresidual stresses on impact resistance of unidirectional fiber composites. Equations also predict lamination residual stresses in multilayered angle ply composites.

  1. Design Concepts for Cooled Ceramic Matrix Composite Turbine Vanes

    Science.gov (United States)

    Boyle, Robert

    2014-01-01

    This project demonstrated that higher temperature capabilities of ceramic matrix composites (CMCs) can be used to reduce emissions and improve fuel consumption in gas turbine engines. The work involved closely coupling aerothermal and structural analyses for the first-stage vane of a high-pressure turbine (HPT). These vanes are actively cooled, typically using film cooling. Ceramic materials have structural and thermal properties different from conventional metals used for the first-stage HPT vane. This project identified vane configurations that satisfy CMC structural strength and life constraints while maintaining vane aerodynamic efficiency and reducing vane cooling to improve engine performance and reduce emissions. The project examined modifications to vane internal configurations to achieve the desired objectives. Thermal and pressure stresses are equally important, and both were analyzed using an ANSYS® structural analysis. Three-dimensional fluid and heat transfer analyses were used to determine vane aerodynamic performance and heat load distributions.

  2. The effect of composition (art or music) on the self-concept of hospitalized children.

    Science.gov (United States)

    Colwell, Cynthia M; Davis, Kathy; Schroeder, Linda K

    2005-01-01

    The purpose of the present study was to determine the effect of composition (art or music) on the self-concept of hospitalized children. The music composition was created using the program Making More Music. The art composition was a drawing using standard medium. The Piers-Harris Children's Self-Concept Scale was used to measure self-concept. When examining subjects as one group, a significant difference from pre- to posttest for the Total score indicated an improved self-concept. Further analyses on each of the 6 categories indicated no significant differences. The art composition group had a significant difference from pre- to posttest for the Total score and for Popularity (POP). Although not significant, scores increased from pre- to posttest for Behavioral Adjustment (BEH), Physical Appearance (PHY), Freedom from Anxiety (FRE), and Happiness and Satisfaction (HAP). The music composition group had no significant difference from pre- to posttest for the Total score but a significant difference from pre- to posttest on Intellectual and School Status (INT) and Physical Appearance (PRY). Although not significant, scores increased from pre- to posttest for TOT, BEH, and HAP. There was a significant difference between the groups on 2 categories that indicated an improved self-concept for the music group under Intellectual and School Status and for the art group under Popularity.

  3. The concept of resistance in Benjamin and Adorno O conceito de resistência em Benjamin e Adorno

    Directory of Open Access Journals (Sweden)

    Natalia A. Morato Fernandes

    2007-05-01

    Full Text Available That work intends, with base in some texts of Theodor Adorno and of Walter Benjamin, to discuss the meaning of the “resistance” concepts and of “conformism” for such authors. These concepts are not elaborated in way explicit or systematic by both, to the opposite they are related subtlety the some aspects of the contemporary social life, as the disappearance of the experience, the decline of the narration, the loss of the sense of the history and the consequent suppression of the memory, the appearance of the cultural industry. Of that it sorts things out, explicit those concepts, especially when referred the those subjects, it helps us not only to understand the conception of Benjamin and Adorno, but also your judgements on the cultural scene of the beginning of the century - without, though, to intend to establish a model of what can be the resistance or the conformism. Keywords: Resistance. Conformism. Culture. Romances. School of Frankfurt. Este trabalho pretende, com base em alguns textos de Theodor Adorno e de Walter Benjamin, discutir o significado dos conceitos de “resistência” e de “conformismo” para tais autores. Esses conceitos não são elaborados de modo explícito ou sistemático por ambos; ao contrário, são sutilmente relacionados a alguns aspectos da vida social contemporânea, como o desaparecimento da experiência, o declínio da narração, a perda do sentido da história e a conseqüente supressão da memória, e o surgimento da indústria cultural. Dessa maneira, explicitar esses conceitos, especialmente quando referidos a essas questões, ajuda-nos não só a entender a concepção de Benjamin e de Adorno, mas também seus juízos sobre a cena cultural do início do século XX - sem, todavia, pretender estabelecer um modelo do que possa ser a resistência ou o conformismo. Palavras-chave: Resistência. Conformismo. Cultura. Romances. Escola de Frankfurt.

  4. Advanced composite structural concepts and materials technologies for primary aircraft structures: Advanced material concepts

    Science.gov (United States)

    Lau, Kreisler S. Y.; Landis, Abraham L.; Chow, Andrea W.; Hamlin, Richard D.

    1993-01-01

    To achieve acceptable performance and long-term durability at elevated temperatures (350 to 600 F) for high-speed transport systems, further improvements of the high-performance matrix materials will be necessary to achieve very long-term (60,000-120,000 service hours) retention of mechanical properties and damage tolerance. This report emphasizes isoimide modification as a complementary technique to semi-interpenetrating polymer networks (SIPN's) to achieve greater processibility, better curing dynamics, and possibly enhanced thermo-mechanical properties in composites. A key result is the demonstration of enhanced processibility of isoimide-modified linear and thermo-setting polyimide systems.

  5. Advanced composite structural concepts and material technologies for primary aircraft structures

    Science.gov (United States)

    Jackson, Anthony

    1991-01-01

    Structural weight savings using advanced composites have been demonstrated for many years. Most military aircraft today use these materials extensively and Europe has taken the lead in their use in commercial aircraft primary structures. A major inhibiter to the use of advanced composites in the United States is cost. Material costs are high and will remain high relative to aluminum. The key therefore lies in the significant reduction in fabrication and assembly costs. The largest cost in most structures today is assembly. As part of the NASA Advanced Composite Technology Program, Lockheed Aeronautical Systems Company has a contract to explore and develop advanced structural and manufacturing concepts using advanced composites for transport aircraft. Wing and fuselage concepts and related trade studies are discussed. These concepts are intended to lower cost and weight through the use of innovative material forms, processes, structural configurations and minimization of parts. The approach to the trade studies and the downselect to the primary wing and fuselage concepts is detailed. The expectations for the development of these concepts is reviewed.

  6. 3D printing-assisted interphase engineering of polymer composites: Concept and feasibility

    Directory of Open Access Journals (Sweden)

    G. Szebenyi

    2017-07-01

    Full Text Available We introduced a general concept to create smart, (multifunctional interphases in polymer composites with layered reinforcements, making use of 3D printing. The concept can be adapted for both thermoplastic and thermoset matrix-based composites with either thermoplastic- or thermoset-enriched interphases. We showed feasibility using an example of a composite containing a thermoset matrix/thermoplastic interphase. Carbon fiber unidirectional reinforcing layers were patterned with poly(ε-caprolactone (PCL through 3D printing, then infiltrated with an amine-cured epoxy (EP. The corresponding composites were subjected to static and dynamic flexure tests. The PCL-rich interphase markedly improved the ductility in static tests without deteriorating the flexural properties. Its effect was marginal in Charpy impact tests, which can be explained with effects of specimen and PCL pattern sizes. The PCL-rich interphase ensured self-healing when triggered by heat treatment above the melting temperature of PCL.

  7. Development of a metal-clad advanced composite shear web design concept

    Science.gov (United States)

    Laakso, J. H.

    1974-01-01

    An advanced composite web concept was developed for potential application to the Space Shuttle Orbiter main engine thrust structure. The program consisted of design synthesis, analysis, detail design, element testing, and large scale component testing. A concept was sought that offered significant weight saving by the use of Boron/Epoxy (B/E) reinforced titanium plate structure. The desired concept was one that was practical and that utilized metal to efficiently improve structural reliability. The resulting development of a unique titanium-clad B/E shear web design concept is described. Three large scale components were fabricated and tested to demonstrate the performance of the concept: a titanium-clad plus or minus 45 deg B/E web laminate stiffened with vertical B/E reinforced aluminum stiffeners.

  8. Concept selection of car bumper beam with developed hybrid bio-composite material

    International Nuclear Information System (INIS)

    Davoodi, M.M.; Sapuan, S.M.; Ahmad, D.; Aidy, A.; Khalina, A.; Jonoobi, Mehdi

    2011-01-01

    Highlights: → We simulate the low impact test by Abaqus Ver16R9 using the same material model. → Six different weighted criteria were discussed to nominate the best concept. → Double Hat Profile showed the best concept to fulfil the defined PDS. → Geometric parameters may overcome the weak inherent properties of bio composite. → Toughened bio-composite material may employ in structural automotive components. -- Abstract: Application of natural fibre composites is going to increase in different areas caused by environmental, technical and economic advantages. However, their low mechanical properties have limited their particular application in automotive structural components. Hybridizations with other reinforcements or matrices can improve mechanical properties of natural fibre composite. Moreover, geometric optimizations have a significant role in structural strength improvement. This study focused on selecting the best geometrical bumper beam concept to fulfill the safety parameters of the defined product design specification (PDS). The mechanical properties of developed hybrid composite material were considered in different bumper beam concepts with the same frontal curvature, thickness, and overall dimensions. The low-speed impact test was simulated under the same conditions in Abaqus V16R9 software. Six weighted criteria, which were deflection, strain energy, mass, cost, easy manufacturing, and the rib possibility were analyzed to form an evaluation matrix. Topsis method was employed to select the best concept. It is concluded that double hat profile (DHP) with defined material model can be used for bumper beam of a small car. In addition, selected concept can be strengthened by adding reinforced ribs or increasing the thickness of the bumper beam to comply with the defined PDS.

  9. Effects of processing method and moisture history on laboratory fungal resistance of wood-HDPE composites.

    Science.gov (United States)

    Craig M. Clemons; Rebecca E. Ibach

    2004-01-01

    The purpose of this study was to clarify the effects of composite processing and moisture sorption on laboratory fungal resistance of wood-plastic composites. A 2-week water soaking or cyclic boiling-drying procedure was used to infuse moisture into composites made from high-density polyethylene filled with 50 percent wood flour and processed by extrusion, compression...

  10. Representing general theoretical concepts in structural equation models: The role of composite variables

    Science.gov (United States)

    Grace, J.B.; Bollen, K.A.

    2008-01-01

    Structural equation modeling (SEM) holds the promise of providing natural scientists the capacity to evaluate complex multivariate hypotheses about ecological systems. Building on its predecessors, path analysis and factor analysis, SEM allows for the incorporation of both observed and unobserved (latent) variables into theoretically-based probabilistic models. In this paper we discuss the interface between theory and data in SEM and the use of an additional variable type, the composite. In simple terms, composite variables specify the influences of collections of other variables and can be helpful in modeling heterogeneous concepts of the sort commonly of interest to ecologists. While long recognized as a potentially important element of SEM, composite variables have received very limited use, in part because of a lack of theoretical consideration, but also because of difficulties that arise in parameter estimation when using conventional solution procedures. In this paper we present a framework for discussing composites and demonstrate how the use of partially-reduced-form models can help to overcome some of the parameter estimation and evaluation problems associated with models containing composites. Diagnostic procedures for evaluating the most appropriate and effective use of composites are illustrated with an example from the ecological literature. It is argued that an ability to incorporate composite variables into structural equation models may be particularly valuable in the study of natural systems, where concepts are frequently multifaceted and the influence of suites of variables are often of interest. ?? Springer Science+Business Media, LLC 2007.

  11. Continuous monitoring of the composition of liquid Pb-17Li eutectic using electrical resistivity methods

    International Nuclear Information System (INIS)

    Hubberstey, P.; Sample, T.; Barker, M.G.

    1991-01-01

    The composition of liquid Pb-17Li alloys has been continously determined, using an electrical resistivity monitor, during their interaction with nitrogen, oxygen, hydrogen and water vapour. The operation of the monitor depends on the fact that the resistivity of liquid Pb-Li alloys is dependent on their composition. Accurate resistivity-composition isotherms have been derived from resistivity-temperature data for 15 Pb-Li alloys (0 Li -8 Ω m (mol% Li) -1 at 725 K) is such that a change of 0.05 mol% Li in the alloy composition can be measured. The addition of oxygen and water vapour resulted in a decrease in the resistivity of the liquid alloy. Neither nitrogen nor hydrogen had any effect. The observed changes were shown to be consistent with Li 2 O formation. (orig.)

  12. Composite-Material Tanks with Chemically Resistant Liners

    Science.gov (United States)

    DeLay, Thomas K.

    2004-01-01

    Lightweight composite-material tanks with chemically resistant liners have been developed for storage of chemically reactive and/or unstable fluids . especially hydrogen peroxide. These tanks are similar, in some respects, to the ones described in gLightweight Composite-Material Tanks for Cryogenic Liquids h (MFS-31379), NASA Tech Briefs, Vol. 25, No. 1 (January, 2001), page 58; however, the present tanks are fabricated by a different procedure and they do not incorporate insulation that would be needed to prevent boil-off of cryogenic fluids. The manufacture of a tank of this type begins with the fabrication of a reusable multisegmented aluminum mandrel in the shape and size of the desired interior volume. One or more segments of the mandrel can be aluminum bosses that will be incorporated into the tank as end fittings. The mandrel is coated with a mold-release material. The mandrel is then heated to a temperature of about 400 F (approximately equal to 200 C) and coated with a thermoplastic liner material to the desired thickness [typically approxiamtely equal to 15 mils (approximately equal to 0.38 mm)] by thermal spraying. In the thermal-spraying process, the liner material in powder form is sprayed and heated to the melting temperature by a propane torch and the molten particles land on the mandrel. The sprayed liner and mandrel are allowed to cool, then the outer surface of the liner is chemically and/or mechanically etched to enhance bonding of a composite overwrap. The etched liner is wrapped with multiple layers of an epoxy resin reinforced with graphite fibers; the wrapping can be done either by manual application of epoxy-impregnated graphite cloth or by winding of epoxy-impregnated filaments. The entire assembly is heated in an autoclave to cure the epoxy. After the curing process, the multisegmented mandrel is disassembled and removed from inside, leaving the finished tank. If the tank is to be used for storing hydrogen peroxide, then the liner material

  13. Long-Term Chemical Resistance of Ecological Epoxy Polymer Composites

    Directory of Open Access Journals (Sweden)

    Bernardeta Debska

    2018-03-01

    Full Text Available Resin concretes belong to a small group of building materials which, besides high strength parameters, also have a very good chemical resistance. This is confirmed by the studies carried out by various research institutions around the world. However, there is little data on the behaviour of composite resin exposed to corrosive solutions for an extended period of time. This article presents the results of the research on weight changes in samples of epoxy mortar modified with poly(ethylene terephthalate glycolysates, immersed for 5 years in four different aggressive media i.e. 10% aqueous solutions of sulphuric and nitric acids, sodium hydroxide, and sodium chloride. The actual average weight changes obtained were compared with the data calculated on the basis of the regression functions fitted to the data recorded after 3.5 years of exposure. This allowed verification of the model selection correctness and evaluation of the effectiveness of the fitted regression curve. In the case of aqueous sodium hydroxide and sodium chloride solutions, it can be assumed that the logarithmic model describes weight changes well. It was observed that the weight of the samples exposed to NaCl solutions and NaOH stabilizes over prolonged monitoring time and reaches a plateau. However, the weight changes in mortar samples immersed for 5 years in aqueous solution of sulphuric and nitric acids quite significantly differ from the data calculated on the basis of the trend line fitted to the results of the tests carried out after 3.5 years of exposure. It seems that the better solution in this case is the selection of an exponential model. In addition, placing the logarithmic trendlines for all corrosive media together on a chart allows to note which of the solutions is the most aggressive. It was found that after 5 years of immersion in aqueous solutions of acids, mortar samples became brittle, and the observation of their fractures confirmed the weakness of the

  14. Low-Cost Repairable Oxidation Resistant Coatings for Carbon-Carbon Composites via CCVD

    National Research Council Canada - National Science Library

    Hendrick, Michelle

    2000-01-01

    ...) thin film process to yield oxidation resistant coatings on carbon-carbon (C-C) composites. Work was on simple coatings at this preliminary stage of investigation, including silicon dioxide, platinum and aluminum oxide...

  15. Fiber Finishes for Improving Galvanic Resistance of Imide-Based Composites

    National Research Council Canada - National Science Library

    Allred, R. E

    1998-01-01

    The objective of this program is the development and demonstration of galvanic corrosion resistant carbon/ BMI composites through the use of reactive finishes to form coatings that isolate the carbon...

  16. Towards mechanisms-guided resistivity-based monitoring of damage evolution in laminated composites

    KAUST Repository

    Lubineau, Gilles; Nouri, Hedi; Selvakumaran, Lakshmi

    2013-01-01

    A convenient health monitoring technique for detecting degradation in laminated composite is to monitor the change of electrical resistance along multiple conduction paths within the structure. Yet, the relations between the global modification

  17. Mechanical Properties and Thermal Shock Resistance Analysis of BNNT/Si3N4 Composites

    Science.gov (United States)

    Wang, Shouren; Wang, Gaoqi; Wen, Daosheng; Yang, Xuefeng; Yang, Liying; Guo, Peiquan

    2018-04-01

    BNNT/Si3N4 ceramic composites with different weight amount of BNNT fabricated by hot isostatic pressing were introduced. The mechanical properties and thermal shock resistance of the composites were investigated. The results showed that BNNT-added ceramic composites have a finer and more uniform microstructure than that of BNNT-free Si3N4 ceramic because of the retarding effect of BNNT on Si3N4 grain growth. The addition of 1.5 wt.% BNNT results in simultaneous increase in flexural strength, fracture toughness, and thermal shock resistance. The analysis of the results indicates that BNNT brings many thermal transport channels in the microstructure, increasing the efficiency of thermal transport, therefore results in increase of thermal shock resistance. In addition, BNNT improves the residual flexural strength of composites by crack deflection, bridging, branching and pinning, which increase the crack propagation resistance.

  18. Mode I and Mode II Interlaminar Crack Growth Resistances of Ceramic Matrix Composites at Ambient Temperature

    National Research Council Canada - National Science Library

    Choi, Sung R; Kowalik, Robert W; Alexander, Donald J

    2007-01-01

    ...) including three gas-turbine grade melt-infiltrated SiC/SiC composites. Modes I and II crack growth resistances, GI and GII, were evaluated at ambient temperature using double cantilever beam and end notched flexure methods, respectively...

  19. Stab Resistance of Shear Thickening Fluid (STF)-Kevlar Composites for Body Armor Applications

    National Research Council Canada - National Science Library

    Egres Jr., R. G; Decker, M. J; Halbach, C. J; Lee, Y. S; Kirkwood, J. E; Kirwood, K. M; Wagner, N. J; Wetzel, E. D

    2004-01-01

    The stab resistance of shear thickening fluid (STF)-Kevlar and STF-Nylon fabric composites are investigated and found to exhibit significant improvements over neat fabric targets of equivalent areal density...

  20. Wireless Damage Monitoring of Laminated CFRP Composites using Electrical Resistance Change

    National Research Council Canada - National Science Library

    Todoroki, Akira

    2007-01-01

    .... In this system, a tiny oscillation circuit is attached to the composite component. When delimitation of the component occurs, electrical resistance changes, which causes a change in the oscillating frequency of the circuit...

  1. Explorative Study on the Concept of Mind Shares: Confidence, Resistance and Loyalty

    Directory of Open Access Journals (Sweden)

    Hui-Hsin HUANG

    2014-03-01

    Full Text Available In practices and academics, the growth/decline of a brand or product sales is often measured with market shares. However, this method does not really gain insight into loyalty and perception of consumers toward brands and products. This paper proposes a concept of Mind Shares which combines confidence and resistance as the main contents of loyalty to establish a new theoretic foundation and develop the calculation method for the quantification of this model. The data from questionnaire survey showed that confidence and resistance are both positively correlated with loyalty, and these two variables are capable of predictability on loyalty. It is considered that this paper lays down the theoretic foundation of Mind Shares and contributes applications.

  2. Novel Repair Concept for Composite Materials by Repetitive Geometrical Interlock Elements

    Directory of Open Access Journals (Sweden)

    David Zaremba

    2011-12-01

    Full Text Available Material adapted repair technologies for fiber-reinforced polymers with thermosetting matrix systems are currently characterized by requiring major efforts for repair preparation and accomplishment in all industrial areas of application. In order to allow for a uniform distribution of material and geometrical parameters over the repair zone, a novel composite interlock repair concept is introduced, which is based on a repair zone with undercuts prepared by water-jet technology. The presented numerical and experimental sensitivity analyses make a contribution to the systematic development of the interlock repair technology with respect to material and geometrical factors of influence. The results show the ability of the novel concept for a reproducible and automatable composite repair.

  3. Concepts for the development of light-weight composite structures for rotor burst containment

    Science.gov (United States)

    Holms, A. G.

    1977-01-01

    Based on published results on rotor burst containment with single materials, and on body armor using composite materials, a set of hypotheses is established as to what variables might control the design of a weight-efficient protective device. Based on modern concepts for the design and analysis of small optimum seeking experiments, a particular experiment for evaluating the hypotheses and materials was designed. The design and methods for the analysis of results are described.

  4. Resistance Welding of Thermoplastic Composites : Process and Performance

    NARCIS (Netherlands)

    Shi, H.

    2014-01-01

    Compared to thermoset composites, thermoplastic composites are drawing more and more attention by aircraft industries not only due to their excellent material properties but also due to their potentials to reduce cycle time and structure cost by using low-cost manufacturing technologies such as

  5. Fatigue resistance of CAD/CAM resin composite molar crowns.

    NARCIS (Netherlands)

    Shembish, F.A.; Tong, H.; Kaizer, M.; Janal, M.N.; Thompson, V.P.; Opdam, N.J.M.; Zhang, Y.

    2016-01-01

    OBJECTIVE: To demonstrate the fatigue behavior of CAD/CAM resin composite molar crowns using a mouth-motion step-stress fatigue test. Monolithic leucite-reinforced glass-ceramic crowns were used as a reference. METHODS: Fully anatomically shaped monolithic resin composite molar crowns (Lava

  6. Pressure and temperature induced electrical resistance change in nano-carbon/epoxy composites

    NARCIS (Netherlands)

    Shen, J. T.; Buschhorn, S. T.; De Hosson, J. Th. M.; Schulte, K.; Fiedler, B.

    2015-01-01

    In this study, we investigate the changes of electrical resistance of the carbon black (CB) and carbon nanotube (CNT) filled epoxy composites upon compression, swelling and temperature variation. For all samples we observe a decrease of electrical resistance under compression, while an increase of

  7. Increased corrosion resistance of basalt reinforced cement compositions with nanosilica

    Directory of Open Access Journals (Sweden)

    URKHANOVA Larisa Alekseevna

    2014-08-01

    Full Text Available Disperse fiber reinforcement is used to improve deformation and shrinkage characteristics, flexural strength of concrete. Basalt roving and thin staple fiber are often used as mineral fibers. The paper considers the problems of using thin basalt fiber produced by centrifugal-blow method. Evaluation of the corrosion resistance of basalt fiber as part of the cement matrix was performed. Nanodispersed silica produced by electron beam accelerator was used to increase corrosion resistance of basalt fiber.

  8. Increased corrosion resistance of basalt reinforced cement compositions with nanosilica

    OpenAIRE

    URKHANOVA Larisa Alekseevna; LKHASARANOV Solbon Aleksandrovich; ROZINA Victoria Yevgenievna; BUYANTUEV Sergey Lubsanovich; BARDAKHANOV Sergey Prokopievich

    2014-01-01

    Disperse fiber reinforcement is used to improve deformation and shrinkage characteristics, flexural strength of concrete. Basalt roving and thin staple fiber are often used as mineral fibers. The paper considers the problems of using thin basalt fiber produced by centrifugal-blow method. Evaluation of the corrosion resistance of basalt fiber as part of the cement matrix was performed. Nanodispersed silica produced by electron beam accelerator was used to increase corrosion resistance of ba...

  9. Fracture strength and fatigue resistance of dental resin-based composites

    NARCIS (Netherlands)

    Keulemans, F.; Palav, P.; Aboushelib, M.M.N.; van Dalen, A.; Kleverlaan, C.J.; Feilzer, A.J.

    2009-01-01

    Objectives: The aim of this study was to evaluate in vitro the influence of fiber-reinforcement on the fracture strength and fatigue resistance of resin-based composites. Methods: One hundred rectangular bar-shaped specimens (2 mm × 2 mm × 25 mm) made of resin-based composite were prepared in a

  10. Effect of magnesium aluminum silicate glass on the thermal shock resistance of BN matrix composite ceramics

    NARCIS (Netherlands)

    Cai, Delong; Jia, Dechang; Yang, Zhihua; Zhu, Qishuai; Ocelik, Vaclav; Vainchtein, Ilia D.; De Hosson, Jeff Th M.; Zhou, Yu

    The effects of magnesium aluminum silicate (MAS) glass on the thermal shock resistance and the oxidation behavior of h-BN matrix composites were systematically investigated at temperature differences from 600 degrees C up to 1400 degrees C. The retained strength rate of the composites rose with the

  11. Fracture resistance of reattached incisor fragments with mini fibre-reinforced composite anchors.

    NARCIS (Netherlands)

    Fennis, W.M.M.; Kreulen, C.M.; Wolke, J.G.C.; Fokkinga, W.A.; Machado, C.; Creugers, N.H.J.

    2009-01-01

    OBJECTIVES: Fractured coronal fragments of incisors can be adhered to the remaining tooth with resin composite, but are prone to failure. This study explores whether mini fibre-reinforced composite (FRC) anchors increase fracture resistance of reattached fragments. METHODS: Forty-five extracted

  12. Conception, analyse et caracterisation des proprietes mecaniques de ressorts composites a renfort tresse

    Science.gov (United States)

    Zebdi, Oussama

    High performance composites reinforced by woven or braided fabrics have several different applications in various fields such as in the aerospace, automobile and marine industry. This research project was carried out at the Ecole Polytechnique de Montreal in collaboration with an industrial sponsor, the company Composites Atlantic Ltd. Composite springs often represent an interesting alternative, given the reduction in weight that they allow with equal mechanical performance compared to metallic springs. Their good resistance to fatigue and corrosion bring additional benefits in several industrial applications. Moreover, the use of the composites increases safety by avoiding the risks of brutal rupture because of the low propagation velocity of cracks in this type of material. Lastly, in electrotechnics, another significant advantage comes into play because of the electrical insulation capability of composite springs. Few research results can be found on composite springs in the scientific literature. The first part of this thesis studies the problems connected with the design of composite springs. The results are promising, because it was confirmed that composite springs can be devised with the same mechanical performance in term of stiffness as metallic ones. Two solutions were found to replace the metallic springs of the suspension of a four wheel drive: the first spring was in carbon-epoxy, and the second one in glass-epoxy. In the second part, software was developed in order to devise a new approach to predict the mechanical properties of woven or braided composites. This work shows how an inverse method based on plate laminate theory allows creating, from experimental results on braided composites, a virtual basic ply that includes the effect of fiber architecture (undulation and braiding angle). Using this model, the properties of the composite can be predicted for any braid angle. The comparison with the experimental results shows a good correlation with

  13. Effects of oxygen plasma treatment power on Aramid fiber III/BMI composite humidity resistance properties

    Science.gov (United States)

    Wang, Jing; Shi, Chen; Feng, Jiayue; Long, Xi; Meng, Lingzhi; Ren, Hang

    2018-01-01

    The effects of oxygen plasma treatment power on Aramid Fiber III chemical structure and its reinforced bismaleimides (BMI) composite humidity resistance properties were investigated in this work. The aramid fiber III chemical structure under different plasma treatment power were measured by FTIR. The composite bending strength and interlinear shear strength with different plasma treatment power before and after absorption water were tested respectively. The composite rupture morphology was observed by SEM. The FTIR results showed that oxygen plasma treatment do not change the fiber bulk chemical structure. The composite humidity resistance of bending strength and interlinear shear strength are similar for untreated and plasma treated samples. The retention rate of composite bending strength and interlinear shear strength are about 75% and 94%, respectively. The composite rupture mode turns to be the fiber failure after water absorption.

  14. Hybrid carbon/glass fiber composites: Micromechanical analysis of structure–damage resistance relationships

    DEFF Research Database (Denmark)

    Mishnaevsky, Leon; Dai, Gaoming

    2014-01-01

    A computational study of the effect of microstructure of hybrid carbon/glass fiber composites on their strength is presented. Unit cells with hundreds of randomly located and misaligned fibers of various properties and arrangements are subject to tensile and compression loading, and the evolution...... strength than pure composites, while the strength of hybrid composites under inform force loading increases steadily with increasing the volume content of carbon fibers....... of fiber damages is analyzed in numerical experiments. The effects of fiber clustering, matrix properties, nanoreinforcement, load sharing rules on the strength and damage resistance of composites are studied. It was observed that hybrid composites under uniform displacement loading might have lower...

  15. Random walks in nanotube composites: Improved algorithms and the role of thermal boundary resistance

    International Nuclear Information System (INIS)

    Duong, Hai M.; Papavassiliou, Dimitrios V.; Lee, Lloyd L.; Mullen, Kieran J.

    2005-01-01

    Random walk simulations of thermal walkers are used to study the effect of interfacial resistance on heat flow in randomly dispersed carbon nanotube composites. The adopted algorithm effectively makes the thermal conductivity of the nanotubes themselves infinite. The probability that a walker colliding with a matrix-nanotube interface reflects back into the matrix phase or crosses into the carbon nanotube phase is determined by the thermal boundary (Kapitza) resistance. The use of 'cold' and 'hot' walkers produces a steady state temperature profile that allows accurate determination of the thermal conductivity. The effects of the carbon nanotube orientation, aspect ratio, volume fraction, and Kapitza resistance on the composite effective conductivity are quantified

  16. Radiolucent Composites Providing High Resistance against Sterilization Decomposition

    Czech Academy of Sciences Publication Activity Database

    Suchý, Tomáš; Balík, Karel; Sedláček, R.; Sucharda, Zbyněk; Sochor, M.; Prokop, J.; Beneš, J.; Křena, J.

    2011-01-01

    Roč. 55, č. 4 (2011), s. 401-409 ISSN 0862-5468 R&D Projects: GA ČR(CZ) GAP108/10/1457 Institutional research plan: CEZ:AV0Z30460519 Keywords : composite material * polymer matrix * radiolucency Subject RIV: JI - Composite Materials Impact factor: 0.382, year: 2011 http://www.ceramics-silikaty.cz/2011/2011_04_401.htm

  17. Fabrication and testing of fire resistant graphite composite panels

    Science.gov (United States)

    Roper, W. D.

    1986-01-01

    Eight different graphite composite panels were fabricated using four different resin matrices. The resin matrices included Hercules 71775, a blend of vinylpolystyrpyridine and bismaleimide, H795, a bismaleimide, Cycom 6162, a phenolic, and PSP 6022m, a polystyrylpyridine. Graphite panels were fabricated using fabric or unidirectional tape. Described are the processes for preparing these panels and some of their mechanical, thermal and flammability properties. Panel properties are compared with state-of-the-art epoxy fiberglass composite panels.

  18. Influence of Heat Treatment on Abrasive Wear Resistance of Silumin Matrix Composite Castings

    Directory of Open Access Journals (Sweden)

    Gawdzińska K.

    2016-03-01

    Full Text Available The authors attempted at examining the effect of heat treatment on abrasive wear resistance of metal composite castings. Metal matrix composites were made by infiltrating preforms created from unordered short fibers (graphite or silumin with liquid aluminium alloy AlSi12(b. Thus prepared composites were subject to solution heat treatment at a temperature of 520°C for four hours, then aging at a temperature of 220°C for four hours. Abrasion resistance of the material was tested before and after thermal treatment.

  19. Enhanced oxidation resistance of carbon fiber reinforced lithium aluminosilicate composites by boron doping

    International Nuclear Information System (INIS)

    Xia, Long; Jin, Feng; Zhang, Tao; Hu, Xueting; Wu, Songsong; Wen, Guangwu

    2015-01-01

    Highlights: • C f /LAS composites exhibit enhanced oxidation resistance by boron doping. • Boron doping is beneficial to the improvement of graphitization degree of carbon fibers. • Graphitization of carbon fibers together with the decrease of viscosity of LAS matrix is responsible to the enhancement of oxidation resistance of C f /LAS composites. - Abstract: Carbon fiber reinforced lithium aluminosilicate matrix composites (C f /LAS) modified with boron doping were fabricated and oxidized for 1 h in static air. Weight loss, residual strength and microstructure were analyzed. The results indicate that boron doping has a remarkable effect on improving the oxidation resistance for C f /LAS. The synergism of low viscosity of LAS matrix at high temperature and formation of graphite crystals on the surface of carbon fibers, is responsible for excellent oxidation resistance of the boron doped C f /LAS.

  20. Preparation of novel functional Mg/O/PCL/ZnO composite biomaterials and their corrosion resistance

    International Nuclear Information System (INIS)

    Xi, Zhongxian; Tan, Cui; Xu, Lan; Yang, Na; Li, Qing

    2015-01-01

    Highlights: • Novel functional Mg/O/PCL/ZnO composite biomaterials were prepared. • The biomaterials were prepared by anodization treatment and dip-coating technique. • The composite biomaterials were smooth and with low porosity. • The prepared biomaterials have good corrosion resistance in SBF. • The composite biomaterials can release zinc ion to promote bone formation. - Abstract: In this study, novel and functional Mg/O/PCL/ZnO (magnesium/anodic film/poly(ε-caprolactone)/zinc oxide) composite biomaterials for enhancing the bioactivity and biocompatibility of the implant was prepared by using anodization treatment and dip-coating technique. The surface morphology, microstructure, adhesion strength and corrosion resistance of the composite biomaterials were investigated using scanning electron microscopy (SEM), adhesion measurements, electrochemical tests and immersion tests respectively. In addition, the biocompatible properties of Mg (magnesium), Mg/PCL (magnesium/poly(ε-caprolactone)) and Mg/O/PCL (magnesium/anodic film/poly(ε-caprolactone)) samples were also investigated. The results show that the Mg/O/PCL/ZnO composite biomaterials were with low porosity and with the ZnO powders dispersed in PCL uniformly. The adhesion tests suggested that Mg/O/PCL/ZnO composite biomaterials had better adhesion strength than that of Mg/PCL composite biomaterials obviously. Besides, an in vitro test for corrosion demonstrated that the Mg/O/PCL/ZnO composite biomaterials had good corrosion resistance and zinc ion was released obviously in SBF

  1. An Introduction to The Interdisciplinary Concept of Risk-Informed Proliferation Resistance

    International Nuclear Information System (INIS)

    Gouveia, Fernando

    2010-01-01

    The nonproliferation community is rich in diverse attempts aimed at predicting and preventing attempts at nuclear proliferation. Such efforts, however, are rarely incorporated into a holistic approach well-suited to solving both existing and emerging proliferation dilemmas. This division is particularly apparent with respect to the partition that separates the socio-political and technical approaches to solving such problems, approaches which are very often developed and utilized in isolation. Complicating matters further, are the diverse positions taken by various entities as they relate to the secure implementation of nuclear energy world-wide. Such positions range from the obdurate belief in the supposed inherent proliferation resistance of traditional spent fuel, to those regarding all nuclear energy systems as inherently proliferation prone, given their core reliance on the sensitive technologies of enrichment and reprocessing. Accordingly, moderates have argued for a risk-informed approach to combat nuclear proliferation, combining institutional factors, such as IAEA safeguards, with innovative reactor and fuel designs to bring about an acceptable notion of proliferation resistance. To this end, methodologies have been developed, which seek to assess and score attained proliferation resistance. Most notably, these include, the Proliferation Resistance and Physical Protection (PR and PP) methodology prepared by the GEN-IV International Forum and the IAEA's International Project on Innovative Nuclear Reactors and Fuel Cycles (INPRO). Such approaches have greatly advanced the concept of proliferation resistance; however, they remain limited by their exclusive concentration on the technological determinants of proliferation and non-consideration of other, equally important, socio-political determinants. This limitation is significant as numerous incidents have illustrated the ability of atypical states to find alternate paths to proliferation, for example

  2. Novel Concepts for Damage-Resistant Alloys in Next Generation Nuclear Power Systems

    Energy Technology Data Exchange (ETDEWEB)

    Stephen M. Bruemmer; Peter L. Andersen; Gary Was

    2002-12-27

    The discovery of a damage-resistant alloy based on Hf solute additions to a low-carbon 316SS is the highlight of the Phase II research. This damage resistance is supported by characterization of radiation-induced microstructures and microchemistries along with measurements of environmental cracking. The addition of Hf to a low-carbon 316SS reduced the detrimental impact of radiation by changing the distribution of Hf. Pt additions reduced the impact of radiation on grain boundary segregation but did not alter its effect on microstructural damage development or cracking. Because cracking susceptibility is associated with several material characteristics, separate effect experiments exploring strength effects using non-irradiated stainless steels were conducted. These crack growth tests suggest that irradiation strength by itself can promote environmental cracking. The second concept for developing damage resistant alloys is the use of metastable precipitates to stabilize the microstructure during irradiation. Three alloys have been tailored for evaluation of precipitate stability influences on damage evolution. The first alloy is a Ni-base alloy (alloy 718) that has been characterized at low neutron irradiation doses but has not been characterized at high irradiation doses. The other two alloys are Fe-base alloys (PH 17-7 and PH 17-4) that have similar precipitate structures as alloy 718 but is more practical in nuclear structures because of the lower Ni content and hence lesser transmutation to He.

  3. Fundamental studies of low velocity impact resistance of graphite fiber reinforced polymer matrix composites

    International Nuclear Information System (INIS)

    Bowles, K.J.

    1985-01-01

    A study was conducted to relate the impact resistance of graphite fiber reinforced composites with matrix properties through gaining an understanding of the basic mechanics involved in the deformation and fracture process, and the effect of the polymer matrix structure on these mechanisms. It was found that the resin matrix structure influences the composite impact resistance in at least two ways. The integration of flexibilizers into the polymer chain structure tends to reduce the T/sub G/ and the mechanical properties of the polymer. The reduction in the mechanical properties of the matrix does not enhance the composite impact resistance because it allows matrix controlled failure to initiate impact damage. Linear polymers, which contain no active groups for cross-linking, do not toughen composites because the fiber-matrix interfacial bond is not of sufficient strength to prevent interfacial failure from occurring. Toughness must be built into the basic polymer backbone and cross-linking structure

  4. Radiation-resistant composite for biological shield of personnel

    Science.gov (United States)

    Barabash, D. E.; Barabash, A. D.; Potapov, Yu B.; Panfilov, D. V.; Perekalskiy, O. E.

    2017-10-01

    This article presents the results of theoretical and practical justification for the use of polymer concrete based on nonisocyanate polyurethanes in biological shield structures. We have identified the impact of ratio: polymer - radiation-resistant filling compound on the durability and protection properties of polymer concrete. The article expounds regression dependence of the change of basic properties of the aforementioned polymer concrete on the absorbed radiation dose rate. Synergy effect in attenuation of radioactivity release in case of conjoint use of hydrogenous polymer base and radiation-resistant powder is also addressed herein.

  5. Erosion resistance and adhesion of composite metal/ceramic coatings produced by plasma spraying

    International Nuclear Information System (INIS)

    Ramm, D.A.J.; Hutchings, I.M.; Clyne, T.W.

    1993-01-01

    Ceramic coatings can exhibit greater erosion resistance than most metallic coatings. Such coatings are conveniently produced by thermal spraying. Unfortunately, thermally sprayed ceramic coatings often exhibit poor adhesion, partly as a consequence of the development of residual stresses during spraying and subsequent cooling. Composite coatings have been studied using aluminium/alumina deposits on steel substrates. The incorporation of ceramics within a ductile matrix has potential for sharply reducing the erosive wear at high erodent impact angles, whilst retaining the good erosion resistance of ceramics at low angles. It is shown that the proportion of metal and ceramic at the free surface can be specified so as to optimise the erosion resistance. Experiments have also been carried out on the resistance of the coatings to debonding during four-point bending of the coated substrate. Progress is being made towards the tailoring of composition profiles in graded coatings so as to optimise the combination of erosion resistance and adhesion. (orig.)

  6. Impact resistance of uncoated SiC/SiC composites

    International Nuclear Information System (INIS)

    Bhatt, Ramakrishna T.; Choi, Sung R.; Cosgriff, Laura M.; Fox, Dennis S.; Lee, Kang N.

    2008-01-01

    Two-dimensional woven SiC/SiC composites fabricated by melt infiltration method were impact tested at room temperature and at 1316 deg. C in air using 1.59-mm diameter steel-ball projectiles at velocities ranging from 115 to 400 m/s. The extent of substrate damage with increasing projectile velocity was imaged and analyzed using optical and scanning electron microscopy, and non-destructive evaluation (NDE) methods such as pulsed thermography, and computed tomography. The impacted specimens were tensile tested at room temperature to determine their residual mechanical properties. Results indicate that at 115 m/s projectile velocity, the composite showed no noticeable surface or internal damage and retained its as-fabricated mechanical properties. As the projectile velocity increased above this value, the internal damage increased and mechanical properties degraded. At velocities >300 m/s, the projectile penetrated through the composite, but the composite retained ∼50% of the ultimate tensile strength of the as-fabricated composite and exhibited non-brittle failure. Predominant internal damages are delamination of fiber plies, fiber fracture and matrix shearing

  7. Unifying concepts linking dissolved organic matter composition to persistence in aquatic ecosystems

    Science.gov (United States)

    Kellerman, Anne M.; Guillemette, François; Podgorski, David C.; Aiken, George R.; Butler, Kenna D.; Spencer, Robert G. M.

    2018-01-01

    The link between composition and reactivity of dissolved organic matter (DOM) is central to understanding the role aquatic systems play in the global carbon cycle; yet, unifying concepts driving molecular composition have yet to be established. We characterized 37 DOM isolates from diverse aquatic ecosystems, including their stable and radiocarbon isotopes (δ13C-dissolved organic carbon (DOC) and Δ14C-DOC), optical properties (absorbance and fluorescence), and molecular composition (ultrahigh resolution mass spectrometry). Isolates encompassed end-members of allochthonous and autochthonous DOM from sites across the United States, the Pacific Ocean, and Antarctic lakes. Modern Δ14C-DOC and optical properties reflecting increased aromaticity, such as carbon specific UV absorbance at 254 nm (SUVA254), were directly related to polyphenolic and polycyclic aromatic compounds, whereas enriched δ13C-DOC and optical properties reflecting autochthonous end-members were positively correlated to more aliphatic compounds. Furthermore, the two sets of autochthonous end-members (Pacific Ocean and Antarctic lakes) exhibited distinct molecular composition due to differences in extent of degradation. Across all sites and end-members studied, we find a consistent shift in composition with aging, highlighting the persistence of certain biomolecules concurrent with degradation time.

  8. Fracture resistance of premolar teeth restored with silorane-based or dimethacrylate-based composite resins.

    Science.gov (United States)

    Akbarian, Golsa; Ameri, Hamideh; Chasteen, Joseph E; Ghavamnasiri, Marjaneh

    2014-01-01

    To restore posterior teeth using low-shrinkage composite to minimize microleakage. To compare the fracture resistance of mesio-occlusal-distal (MOD) cavity preparations restored with either low-shrinkage composite or with dimethacrylate-based composite in conjunction with cavity liners and without them. The null hypothesis of the study is that there are no differences in either fracture resistance or fracture mode between the silorane group and dimethacrylate groups with and without the use of cavity liners. Sixty maxillary premolars were divided into six groups of 10. MOD cavities were prepared in four groups: F: posterior composite (Filtek P60); GF: 0.5-mm Glass Ionomer (Fuji LC) + posterior composite; FF: 0.5-mm flowable composite (Filtek Supreme XT) + posterior composite; and S: low-shrinkage composite (Filtek P90). Negative (N) and positive (P) control groups consisted of unrestored and sound teeth, respectively. The specimens were thermocycled and loaded. Data were analyzed using analysis of variance, Tukey, and chi-square tests (α = 0.05). Groups FF (1643.09 ± 187/80 N) and GF (1596.80 ± 163/93 N) (p = 0.06 > 0.05) were statistically identical, although less than group P (1742/33 ± 110/08 N), but still demonstrated greater fracture resistance than the other groups. The fracture resistance of group S (1434/69 ± 107/62 N) was identical to GF and FF (p = 0.06 > 0.05). The fracture resistance of F (1353/19 ± 233/90 N) was less than GF and FF, and statistically identical to S (p = 0.87 > 0.05). Silorane-based composite showed a resistance to fracture similar to methacrylate-based composite restorations regardless of whether cavity liners were used. The findings of this study support the selection of silorane-based composite for the restoration of maxillary premolars with standardized Class II cavity preparations in order to strengthen the resistance to fracture to the same extent as do dimethacrylate

  9. Effect of different glass and zeolite A compositions on the leach resistance of ceramic waste forms

    International Nuclear Information System (INIS)

    Lewis, M.A.; Hash, M.; Glandorf, D.

    1996-01-01

    A ceramic waste form is being developed for waste generated during electrometallurgical treatment of spent nuclear fuel. The waste is generated when fission products are removed from the electrolyte, LiCl-KCl eutectic. The waste form is a composite fabricated by hot isostatic pressing a mixture of glass frit and zeolite occluded with fission products and salt. Normalized release rate is less than 1 g/m 2 d for all elements in MCC-1 leach test run for 28 days in deionized water at 90 C. This leach resistance is comparable to that of early Savannah River glasses. We are investigating how leach resistance is affected by changes in cationic form of zeolite and in glass composition. Composites were made with 3 forms of zeolite A and 6 glasses. We used 3-day ASTM C1220-92 (formerly MCC-1) leach tests to screen samples for development purposes only. The leach test results show that the glass composites of zeolites 5A and 4A retain fission products equally well. Loss of Cs is small (0.1-0.5 wt%), while the loss of divalent and trivalent fission products is one or more orders of magnitude smaller. Composites of 5A retain chloride ion better in these short-term screens than 4A and 3A. The more leach resistant composites were made with durable glasses rich in silica and poor in alkaline earth oxides. XRD show that a salt phase was absent in the leach resistant composites of 5A and the better glasses but was present in the other composites with poorer leach performance. Thus, absence of salt phase corresponds to improved leach resistance. Interactions between zeolite and glass depend on composition of both

  10. Investigation of a bearingless helicopter rotor concept having a composite primary structure

    Science.gov (United States)

    Bielawa, R. L.; Cheney, M. C., Jr.; Novak, R. C.

    1976-01-01

    Experimental and analytical investigations were conducted to evaluate a bearingless helicopter rotor concept (CBR) made possible through the use of the specialized nonisotropic properties of composite materials. The investigation was focused on four principal areas which were expected to answer important questions regarding the feasibility of this concept. First, an examination of material properties was made to establish moduli, ultimate strength, and fatigue characteristics of unidirectional graphite/epoxy, the composite material selected for this application. The results confirmed the high bending modulus and strengths and low shear modulus expected of this material, and demonstrated fatigue properties in torsion which make this material ideally suited for the CBR application. Second, a dynamically scaled model was fabricated and tested in the low speed wind tunnel to explore the aeroelastic characteristics of the CBR and to explore various concepts relative to the method of blade pitch control. Two basic control configurations were tested, one in which pitch flap coupling could occur and another which eliminated all coupling. It was found that both systems could be operated successfully at simulated speeds of 180 knots; however, the configuration with coupling present revealed a potential for undesirable aeroelastic response. The uncoupled configuration behaved generally as a conventional hingeless rotor and was stable for all conditions tested.

  11. Equivalent network for resistance and temperature coefficient of resistance versus temperature and composition of thick resistive films

    International Nuclear Information System (INIS)

    Kusy, A.

    1987-01-01

    Two types of elementary resistances in thick resistive films have been considered: (i) constriction resistance R/sub C/ determined by the bulk properties of conducting material and by the geometry of constriction, and (ii) barrier resistance R/sub B/ determined by the parameters of a thermally activated type of tunneling process and by the geometry of the metal-insulator-metal unit. On this basis a resistance network composed of a large number of the two types of resistances has been defined. The network has been considered as being equivalent to thick resistive film (TRF) from the point of view of the resistance and temperature coefficient of resistance (TCR). The parameters of this network have been evaluated by the computer-aided approximation of the experimental data found for RuO 2 -based TRFs. On the basis of the equations derived for the network as well as the results of the approximation process, it can be concluded that the small values of the network TCR result from the superposition of the TCR of the conducting component β/sub C/ and of the temperature coefficient of barrier resistance α/sub B/. In this superposition β/sub C/ is attenuated (by 1--2 orders of magnitude), while α/sub B/ is attenuated by only few percentages. The network has been found to be strongly barrier dominated

  12. Development of in-situ ZrC reinforced iron based composites for wear resistance applications

    International Nuclear Information System (INIS)

    Bandyopadhyay, T.K.; Das, K.

    2002-01-01

    A common objective behind the processing of iron-based composites is to improve the wear resistance of steels by incorporating some reinforcing phases, e.g., carbides and oxides. In the present investigation, iron-based zirconium carbide reinforced composite is produced by the aluminothermic reduction of zircon sand (ZrSiO 4 ) and blue dust (Fe 2 O 3 ) in the presence of carbon. Aluminothermic reduction of blue dust and zircon sand, being highly exothermic in nature, essentially leads to a self-propagating high-temperature synthesis (SHS) of the Fe-ZrC composite. The as-cast composite is characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The mechanical properties of the composite and the effect of heat treatment on the microstructure are evaluated. The composite possess sufficient hardness and promising abrasive wear resistance property. The abrasive wear resistance property of the Fe-ZrC composite is compared with that of a M2 grade tool material and it is found to be better than the tool material. The composite also possess good high temperature stability. (author)

  13. An electrical resistivity monitor for the detection of composition changes in Pb-17Li

    International Nuclear Information System (INIS)

    Hubberstey, P.; Barker, M.G.; Sample, T.

    1991-01-01

    An electrical resistivity monitor for the detection of composition changes in the lithium-lead eutectic alloy, Pb-17Li, has been developed. A miniature electromagnetic pump is used to sample alloy continuously from a pool or loop system and force it through a capillary section, within which the necessary resistance measurements are made, prior to its return to the bulk source. To calibrate the monitor, detailed resistivity-temperature and resistivity-composition data have been determined for Pb-Li alloys at temperatures from 600 to 800K and compositions from 0 to 20.5 at% Li. The resistivity increases with both temperature and composition; for Pb-17li at 723 K, dρ/dT=0.054x10 -8 ΩmK -1 , and dρ/d[Li]=1.27x10 -8 Ωm(at% Li) -1 . The sensitivity of the monitor is such that changes in composition of as little as ±0.05 at% Li can be detected and its response time is limited soley by the rate of sampling. (orig.)

  14. Specific features in the behavior of electrical resistivity of the pine biocarbon preform/copper composite

    Science.gov (United States)

    Burkov, A. T.; Orlova, T. S.; Smirnov, B. I.; Smirnov, I. A.; Misiorek, H.; Jezowski, A.

    2010-11-01

    The electrical resistivity ρ( T) of the novel type of composites prepared by infiltrating melted copper in vacuum in empty sap channels of white pine high-porosity biocarbon preforms has been measured in the temperature range 5-300 K. Biocarbon preforms have been prepared by pyrolysis of tree wood in an argon flow at two carbonization temperatures, 1000 and 2400°C. The electrical resistivity of the composites has been found to vary relatively weakly with temperature and to pass through a characteristic minimum near 40-50 K, which can be ascribed to iron and manganese impurities penetrating into copper from the carbon preform when liquid copper is infiltrated into it. It has been shown that the electrical resistivity ρ( T) of the composites is governed primarily by the specific microstructure of the preform, which is made up of parallel channels with an average diameter of about 50 μm interrupted by systems of thin capillaries. The small cross section of the copper-filled capillaries accounts for these regions providing the major contribution to the electrical resistivity of the composites. An increase in the wood carbonization temperature brings about a noticeable increase in the effective capillary cross section and a decrease in the electrical resistivity ρ( T) of the composite.

  15. Role of certain cellular composition in radio-resistant fungi

    International Nuclear Information System (INIS)

    Shahin, A.A.M.; Hammad, A.A.I.; Hazaa, M.M.; Swelim, M.A.; Mohamed, Y.A.

    2007-01-01

    Fifty three fungal isolates of genera Curvularia, Alternaria and Fusarium were isolated from different sources included crops, vegetables, fruits in addition to bread, chicken feed soil and air. Five isolates were selected from each genus according to the difference in the morphological characters and its source. The fifteen isolates were exposed to increasing doses of gamma rays from 0.5 to 10.0 I 10 values when irradiated in saline solution were found to be 1.92,1.25, 1.47,0.47,1.31 and 0.70 respectively while their D 10 values were 2.25, 1.56, 1.70, 1.30, 1.83 and 1.23 as the irradiation process was done in their natural sources. The values of total protein, total lipids and total nucleic acids either RNA or DNA were relatively higher in radio-resistant strains than sensitive ones. Amino acids containing sulfur (cysteine, methionine) or double bonds (histidine) and the percentage of unsaturated fatty acids were also higher in resistant strains than the sensitive ones. Exposing the six selected strains to dose level 4 kGy obviously decreased each of total protein, total amino acids and total nucleic acids especially DNA and the values of decreases were found to be higher in sensitive than the resistant strains. Dose level 12.5 kGy was quiet enough to eliminate the radioresistant fungi from the contaminated food whatever the level of contamination is

  16. Study of advanced composite structural design concepts for an arrow wing supersonic cruise configuration

    Science.gov (United States)

    Turner, M. J.; Grande, D. L.

    1978-01-01

    Based on estimated graphite and boron fiber properties, allowable stresses and strains were established for advanced composite materials. Stiffened panel and conventional sandwich panel concepts were designed and analyzed, using graphite/polyimide and boron/polyimide materials. The conventional sandwich panel was elected as the structural concept for the modified wing structure. Upper and lower surface panels of the arrow wing structure were then redesigned, using high strength graphite/polyimide sandwich panels, retaining the titanium spars and ribs from the prior study. The ATLAS integrated analysis and design system was used for stress analysis and automated resizing of surface panels. Flutter analysis of the hybrid structure showed a significant decrease in flutter speed relative to the titanium wing design. The flutter speed was increased to that of the titanium design by selective increase in laminate thickness and by using graphite fibers with properties intermediate between high strength and high modulus values.

  17. Development of Composite Materials Under Ecological Aspects as Recycling Concept For Borosilicate Glass Containing Iron Slags

    International Nuclear Information System (INIS)

    Khalil, T.K.; Bossert, J.; Aly, H.F.; Bossert, J.

    1999-01-01

    Composite concept in materials science can be conveniently applied in the waste treatment technology to construct specific t ailor made c omposite materials, in which at least one of the phases is built by the waste material. In this work the applicability of this concept for the fixation and recycling of slags wastes is done, whereby different mixtures of blast furnace slags are mixed with two different borosilicate glasses, which serve as matrix material. Thermal behaviour of the produced compacts were studied. Both melting and powder technology are applied for the fabrication of dense products. The microstructure of sintered samples is investigated by electron microscopy. The mechanical properties such as hardness and fracture toughness are determined by a Vickers technique. An improvement of the fracture toughness of more than 50% over the value for the original glass VG 98 is achieved by slag addition

  18. Strain-dependent electrical resistance of multi-walled carbon nanotube/polymer composite films

    International Nuclear Information System (INIS)

    Park, Myounggu; Kim, Hyonny; Youngblood, Jeffrey P

    2008-01-01

    The strain-dependent electrical resistance characteristics of multi-walled carbon nanotube (MWCNT)/polymer composite films were investigated. In this research, polyethylene oxide (PEO) is used as the polymer matrix. Two representative volume fractions of MWCNT/PEO composite films were selected: 0.56 vol% (near the percolation threshold) and 1.44 vol% (away from the percolation threshold) of MWCNT. An experimental setup which can measure electrical resistance and strain simultaneously and continuously has been developed. Unique and repeatable relationships in resistance versus strain were obtained for multiple specimens with different volume fractions of MWCNT. The overall pattern of electrical resistance change versus strain for the specimens tested consists of linear and nonlinear regions. A resistance change model to describe the combination of linear and nonlinear modes of electrical resistance change as a function of strain is suggested. The unique characteristics in electrical resistance change for different volume fractions imply that MWCNT/PEO composite films can be used as tunable strain sensors and for application into embedded sensor systems in structures

  19. UV resistibility of a nano-ZnO/glass fibre reinforced epoxy composite

    International Nuclear Information System (INIS)

    Wong, Tsz-ting; Lau, Kin-tak; Tam, Wai-yin; Leng, Jinsong; Etches, Julie A.

    2014-01-01

    Highlights: • A GFRE composite with UV resistibility is introduced. • The bonding behaviour and UV resistibility of the composite were studied upon the addition of nano-ZnO particles. • The solvent effect in the dispersion of nano-ZnO particles was also studied. • The nano-ZnO/GFRE composite shows effective UV absorption with enhanced bonding behaviour. - Abstract: The harmfulness of ultraviolet (UV) radiation (UVR) to human health and polymer degradation has been the focus recently in all engineering industries. A polymer-based composite filled with nano-ZnO particles can enhance its UV resistibility. It has been found that the use of appropriate amount of nano-ZnO/Isopropyl alcohol solvent to prepare a UV resistant nano-ZnO/glass fibre reinforced epoxy (ZGFRE) composite can effectively block the UV transmission with negligible influence on the crystal structure of its resin system. This paper aims at investigating the interfacial bonding behaviour and UV resistibility of a ZGFRE composite. The solvent effect in relation to the dispersion properties of ZnO in the composite is also discussed. XRD results indicated that 20 wt% Isopropyl alcohol was an effective solvent for filling nano-ZnO particles into an epoxy. SEM examination also showed that the bonding behaviour between glass fibre and matrix was enhanced after filling 20 wt% nano-ZnO particles with 20 wt% Isopropyl alcohol into the composite. Samples filled with 20 wt% nano-ZnO/Isopropyl alcohol and 40 wt% nano-ZnO/Isopropyl alcohol has full absorption of UVA (315–400 nm), UVB (280–315 nm) and a part of UVC (190–280 nm)

  20. Proton Conducting Graphene Oxide/Chitosan Composite Electrolytes as Gate Dielectrics for New-Concept Devices.

    Science.gov (United States)

    Feng, Ping; Du, Peifu; Wan, Changjin; Shi, Yi; Wan, Qing

    2016-09-30

    New-concept devices featuring the characteristics of ultralow operation voltages and low fabrication cost have received increasing attention recently because they can supplement traditional Si-based electronics. Also, organic/inorganic composite systems can offer an attractive strategy to combine the merits of organic and inorganic materials into promising electronic devices. In this report, solution-processed graphene oxide/chitosan composite film was found to be an excellent proton conducting electrolyte with a high specific capacitance of ~3.2 μF/cm 2 at 1.0 Hz, and it was used to fabricate multi-gate electric double layer transistors. Dual-gate AND logic operation and two-terminal diode operation were realized in a single device. A two-terminal synaptic device was proposed, and some important synaptic behaviors were emulated, which is interesting for neuromorphic systems.

  1. Fracture Resistance Evaluation of Fibre Reinforced Brittle Matrix Composites

    Czech Academy of Sciences Publication Activity Database

    Dlouhý, Ivo; Chlup, Zdeněk

    2005-01-01

    Roč. 290, - (2005), s. 167-174 ISSN 1013-9826. [Fractography of Advanced Ceramic s /2./. Stará Lesná, 03.10.2004-06.10.2004] R&D Projects: GA AV ČR(CZ) IAA2041003; GA ČR(CZ) GA101/02/0683 Keywords : fibre-reinforced ceramic s * glass matrix composites * chevron notch Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 0.224, year: 2005

  2. Fracture resistance of endodontically treated teeth restored with a bulkfill flowable material and a resin composite.

    Science.gov (United States)

    Isufi, Almira; Plotino, Gianluca; Grande, Nicola Maria; Ioppolo, Pietro; Testarelli, Luca; Bedini, Rossella; Al-Sudani, Dina; Gambarini, Gianluca

    2016-01-01

    To determine and compare the fracture resistance of endodontically treated teeth restored with a bulk fill flowable material (SDR) and a traditional resin composite. Thirty maxillary and 30 mandibular first molars were selected based on similar dimensions. After cleaning, shaping and filling of the root canals and adhesive procedures, specimens were assigned to 3 subgroups for each tooth type (n=10): Group A: control group, including intact teeth; Group B: access cavities were restored with a traditional resin composite (EsthetX; Dentsply-Italy, Rome, Italy); Group C: access cavities were restored with a bulk fill flowable composite (SDR; Dentsply-Italy), except 1.5 mm layer of the occlusal surface that was restored with the same resin composite as Group B. The specimens were subjected to compressive force in a material static-testing machine until fracture occurred, the maximum fracture load of the specimens was measured (N) and the type of fracture was recorded as favorable or unfavorable. Data were statistically analyzed with one-way analysis of variance (ANOVA) and Bonferroni tests (Pcomposite and with a bulk fill flowable composite (SDR) was similar in both maxillary and mandibular molars and showed no significant decrease in fracture resistance compared to intact specimens. No significant difference was observed in the mechanical fracture resistance of endodontically treated molars restored with traditional resin composite restorations compared to bulk fill flowable composite restorations.

  3. The Causal-Compositional Concept of Information Part I. Elementary Theory: From Decompositional Physics to Compositional Information

    Directory of Open Access Journals (Sweden)

    Gerhard Luhn

    2012-03-01

    Full Text Available This first part of the study introduces an elementary concept of information. Our interest for newness, our curiosity in the new, will be considered as a main building block of information, and of reality itself. A typical definition of information (the reduction of uncertainty needs to be fundamentally inverted: Information is a compositional activity, including the inconsistent, the paradox, the contradiction and the incoherent meaning. This study expands on the analysis of the composition of new structure (new macrophysical laws, and the analysis of the causality and causal state of such structures (“causally active symbols”. The classical, scientific-objective, passive understanding of information gives meaning to the fact that modern information technology does not by itself lead to an increase of human values. However, our social and moral stance is an informational one, and our informational, active conscious process holds the power to mediate and to enforce this process towards an enriched life. The indicator for such enrichment is given to us by information, and the knowledge about this process will feed us with energy to move towards an active spirit of ethics, and towards the information society. Part I of this study expands on the fundament basis and on our intrinsic responsibility to release the forces that are based on the active dimension of information. Those forces are required in order to reveal the so-called information society from its metaphorical character (Part II.

  4. Thickness effect on electric resistivity on polystyrene and carbon black- based composites

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Lopez, S; Vigueras-Santiago, E [Laboratorio de Investigacion y Desarrollo de Materiales Avanzados (LIDMA) Facultad de Quimica, Paseo Colon Esquina con Paseo Tollocan, s/n, CP 50000, Toluca (Mexico); Mayorga-Rojas, M; Reyes-Contreras, D, E-mail: eviguerass@uaemex.m [Facultad de Ciencias, Universidad Autonoma del Estado de Mexico. Av. Instituto Literario 100 Ote. C. P. 50000, Toluca (Mexico)

    2009-05-01

    Changes on electrical resistivity were experimentally studied for polystyrene and carbon black-based composites respect to the temperature. 22% w/w carbon black composite films at 30{mu}m, 2mm y 1cm thick were submitted to thermal heating-cooling cycles from room temperature to 100 deg. C, slightly up to T{sub g} of the composite. For each cycle changes on electrical resistivity constituent a hysteresis loop that depends on the sample thickness. The changes during the heating stage could be explained as a consequence of the thermal expansion and mobility of the polymer chains at T{sub g}, producing a disconnecting of the electrical contacts among carbon black particles and an important increasing (200%) of the electrical resistivity. For each cycle, the hysteresis loop was observed in thicker samples, whereas for 30 mu m thickness sample the hysteresis loop was lost after four cycles.

  5. Implementation of an active instructional design for teaching the concepts of current, voltage and resistance

    Science.gov (United States)

    Orlaineta-Agüero, S.; Del Sol-Fernández, S.; Sánchez-Guzmán, D.; García-Salcedo, R.

    2017-01-01

    In the present work we show the implementation of a learning sequence based on an active learning methodology for teaching Physics, this proposal tends to promote a better learning in high school students with the use of a comic book and it combines the use of different low-cost experimental activities for teaching the electrical concepts of Current, Resistance and Voltage. We consider that this kind of strategy can be easily extrapolated to higher-education levels like Engineering-college/university level and other disciplines of Science. To evaluate this proposal, we used some conceptual questions from the Electric Circuits Concept Evaluation survey developed by Sokoloff and the results from this survey was analysed with the Normalized Conceptual Gain proposed by Hake and the Concentration Factor that was proposed by Bao and Redish, to identify the effectiveness of the methodology and the models that the students presented after and before the instruction, respectively. We found that this methodology was more effective than only the implementation of traditional lectures, we consider that these results cannot be generalized but gave us the opportunity to view many important approaches in Physics Education; finally, we will continue to apply the same experiment with more students, in the same and upper levels of education, to confirm and validate the effectiveness of this methodology proposal.

  6. Delamination Detection in Carbon Fibre Reinforced Composites Using Electrical Resistance Measurement

    International Nuclear Information System (INIS)

    Kovalovs, A; Rucevskis, S; Kulakov, V; Aniskevich, A

    2016-01-01

    In the present study 2-D numerical analysis of strip-type laminated composite specimens with and without damage is considered and numerical investigation is carried out by using a finite element method. The surface and oblique resistances are numerically calculated according to the two-probe and four-probe methods. The electrical conductivity of the composite laminate in the longitudinal direction is constant, while the electrical conductivity in the through-thickness direction is used as a variable in the parametric study. The resistance change due to delamination for each case is estimated by comparing the obtained resistance with the corresponding resistance of the specimen without delamination. Applicability and effectiveness of the proposed method are investigated by using various lengths of a delaminated crack in the specimen. (paper)

  7. High-Temperature Ceramic Matrix Composite with High Corrosion Resistance

    Science.gov (United States)

    2010-06-02

    description of high temperature oxidation processes of composite ceramic materials of ZrB2 - SiC and ZrB2-SiC-Zr(Mo)Si2 systems up to high (~1300 °C...analysis was applied using MІN-7 mineralogical microscope and a set of standard immersion liquids with the known values of refraction coefficients...2.0 V) corresponds to the simultaneous formation of ZrO2 zirconium dioxide of monoclinic modification and Zr(OH)4 zirconium hydroxide which is

  8. FIRE-RESISTANCE PROPERTIES RESEARCH OF “WATER GLASS - GRAPHITE MICROPARTICLES” COMPOSITE MATERIAL

    Directory of Open Access Journals (Sweden)

    E. A. Pitukhin

    2016-03-01

    Full Text Available Subject of Research. Research results of the fire-resistance for “water glass - graphite microparticles” composite material (CM are given. The method for fire-resistance test of the micro composition is suggested in order to determine the limit state of the experimental samples under hightemperature action. Method. Test-benchequipment being used for research includes metering devices of temperature and time, as well as laboratory electric furnace PL20 with a maximum temperature in the chamber up to 1250ºC. Fire-resistance limit for the test samples of composite material is determined by the loss of insulating ability (I. For that purpose, the time is obtained from the test beginning with the standard temperature mode up to a limiting condition. Main Results. In accordance with the requirements of regulatory documents fire-resistance limit I15 has been obtained equal to 15 minutes. The qualitative and quantitative phase analysis of the CM structure has been done. By the study of samples by X-ray diffraction and electron microscopy we have determined that the material retains the same chemical structure with a monotonic heating above 700° C. Practical Relevance. The composite material with obtained characteristics can be used as a protective coating for building constructions with the aim of fire-resistance enhancement and fuel hazard reduction.

  9. Preparation of electrodes on cfrp composites with low contact resistance comprising laser-based surface pre-treatment

    KAUST Repository

    Almuhammadi, Khaled Hamdan; Lubineau, Gilles; Alfano, Marco Francesco; Buttner, Ulrich

    2016-01-01

    Various examples are provided related to the preparation of electrodes on carbon fiber reinforced polymer (CFRP) composites with low contact resistance. Laser-based surface preparation can be used for bonding to CFRP composites. In one example, a

  10. Preparation of electrodes on cfrp composites with low contact resistance comprising laser-based surface pre-treatment

    KAUST Repository

    Almuhammadi, Khaled Hamdan

    2016-12-29

    Various examples are provided related to the preparation of electrodes on carbon fiber reinforced polymer (CFRP) composites with low contact resistance. Laser-based surface preparation can be used for bonding to CFRP composites. In one example, a method includes preparing a pretreated target area on a CFRP composite surface using laser pulsed irradiation and bonding an electrode to exposed fibers in the pretreated target area. The surface preparation can allow the electrode to have a low contact resistance with the CFRP composite.

  11. Study of advanced composite structural design concepts for an arrow wing supersonic cruise configuration, task 3

    Science.gov (United States)

    1978-01-01

    A structural design study was conducted to assess the relative merits of structural concepts using advanced composite materials for an advanced supersonic aircraft cruising at Mach 2.7. The configuration and structural arrangement developed during Task I and II of the study, was used as the baseline configuration. Allowable stresses and strains were established for boron and advanced graphite fibers based on projected fiber properties available in the next decade. Structural concepts were designed and analyzed using graphite polyimide and boron polyimide, applied to stiffened panels and conventional sandwich panels. The conventional sandwich panels were selected as the structural concept to be used on the wing structure. The upper and lower surface panels of the Task I arrow wing were redesigned using high-strength graphite polyimide sandwich panels over the titanium spars and ribs. The ATLAS computer system was used as the basis for stress analysis and resizing the surface panels using the loads from the Task II study, without adjustment for change in aeroelastic deformation. The flutter analysis indicated a decrease in the flutter speed compared to the baseline titanium wing design. The flutter analysis indicated a decrease in the flutter speed compared to the baseline titanium wing design. The flutter speed was increased to that of the titanium wing, with a weight penalty less than that of the metallic airplane.

  12. Microstructure and wear resistance of in situ porous TiO/Cu composites

    Science.gov (United States)

    Qin, Qingdong; Huang, Bowei; Li, Wei

    2016-07-01

    An in situ porous TiO/Cu composite is successfully prepared using powder metallurgy by the reaction of Ti2CO and Cu powder. Morphological examination of the composite shows that the porosity of composites lies in the range between 10.2% and 35.2%. Dry sliding un-lubricated wear tests show that the wear resistance of the composite is higher than that of the Cu-Al alloy ingot. The coefficient of friction test shows that, as the volume fraction of the reinforced phase increases, the coefficient of friction decreases. The wear rate variation trend of the oil-lubricated wear test results is similar to that of the un-lubricated wear test results. The coefficient of friction for oil lubrication is similar for different volume fractions of the reinforced phase. The wear resistance of the composite at a sliding velocity of 200 rpm is slightly larger than that at 50 rpm. The porosity of the composites enhances the high-velocity oil-lubricated sliding wear resistance.

  13. Preparation and corrosion resistance of magnesium phytic acid/hydroxyapatite composite coatings on biodegradable AZ31 magnesium alloy.

    Science.gov (United States)

    Zhang, Min; Cai, Shu; Zhang, Feiyang; Xu, Guohua; Wang, Fengwu; Yu, Nian; Wu, Xiaodong

    2017-06-01

    In this work, a magnesium phytic acid/hydroxyapatite composite coating was successfully prepared on AZ31 magnesium alloy substrate by chemical conversion deposition technology with the aim of improving its corrosion resistance and bioactivity. The influence of hydroxyapatite (HA) content on the microstructure and corrosion resistance of the coatings was investigated. The results showed that with the increase of HA content in phytic acid solution, the cracks on the surface of the coatings gradually reduced, which subsequently improved the corrosion resistance of these coated magnesium alloy. Electrochemical measurements in simulated body fluid (SBF) revealed that the composite coating with 45 wt.% HA addition exhibited superior surface integrity and significantly improved corrosion resistance compared with the single phytic acid conversion coating. The results of the immersion test in SBF showed that the composite coating could provide more effective protection for magnesium alloy substrate than that of the single phytic acid coating and showed good bioactivity. Magnesium phytic acid/hydroxyapatite composite, with the desired bioactivity, can be synthesized through chemical conversion deposition technology as protective coatings for surface modification of the biodegradable magnesium alloy implants. The design idea of the new type of biomaterial is belong to the concept of "third generation biomaterial". Corrosion behavior and bioactivity of coated magnesium alloy are the key issues during implantation. In this study, preparation and corrosion behavior of magnesium phytic acid/hydroxyapatite composite coatings on magnesium alloy were studied. The basic findings and significance of this paper are as follows: 1. A novel environmentally friendly, homogenous and crack-free magnesium phytic acid/hydroxyapatite composite coating was fabricated on AZ31 magnesium alloy via chemical conversion deposition technology with the aim of enhancing its corrosion resistance and

  14. The fibre orientation influence in cementitious composite against extreme load resistance

    Science.gov (United States)

    Lovichova, R.; Fornusek, J.; Mara, M.; Kocova, M.; Rihova, Z.

    2018-02-01

    This paper is focused on resistance of steel fibre-reinforced cement composite against impact of the deformable projectile shot from the 7.62 × 39 caliber. Different values of resistance against impact of the projectile are caused by different orientation of the fibres. The influence of formwork position, which is the main cause of the different orientation of the fibres, is investigated. The resistance was examined on thirty slabs made of ultra-high performance fibre-reinforced concrete (UHPFRC). Fifteen specimens with vertical orientation of formwork and fifteen with horizontal orientation of formwork was made. The resistance is classified according to the visual evaluation and local damage measurement on the front side and the rear side of the examined specimens. The experiment shown positive influence of vertically oriented formwork on the slabs according to their resistance against impact of the projectile.

  15. New Design Concept for a Lifting Platform Made of Composite Material

    Science.gov (United States)

    Solazzi, L.; Scalmana, R.

    2013-08-01

    Elevating work platforms are hoists equipment that are increasingly used in many applications, like in the construction industry and in the maintenance field. The maintenance of the hub of the wind turbines, for example, can be done through the use of a working platform; these structures have to reach great heights and obviously they have to satisfy the constraints induced by the highway standards, like the maximum axle load and the maximum overall dimensions. To satisfy these requests the material of the structures changed from the classic structural steel (S235 JR, S275 JR or S355JR) to high strength steel (S700 to S1100 or more), characterized by a significantly higher specific resistance. The idea of this paper is to use a composite material for the construction of the arms of an elevating platform in order to reduce the global weight of the machine. The analyses on the new kind of platform show the technical possibility to change the material of the arms with composite materials and this produces a significant reduction of the weight of the machine components, about 50 %. Being a feasibility study, still remain open some problems such as the mechanical behavior of the used composite materials (fatigue, environment effects, etc.).

  16. Effect of aggregate graining compositions on skid resistance of Exposed Aggregate Concrete pavement

    Science.gov (United States)

    Wasilewska, Marta; Gardziejczyk, Wladysław; Gierasimiuk, Pawel

    2018-05-01

    The paper presents the evaluation of skid resistance of EAC (Exposed Aggregate Concrete) pavements which differ in aggregate graining compositions. The tests were carried out on concrete mixes with a maximum aggregate size of 8 mm. Three types of coarse aggregates were selected depending on their resistance to polishing which was determined on the basis of the PSV (Polished Stone Value). Basalt (PSV 48), gabbro (PSV 50) and trachybasalt (PSV 52) aggregates were chosen. For each type of aggregate three graining compositions were designed, which differed in the content of coarse aggregate > 4mm. Their content for each series was as follows: A - 38%, B - 50% and C - 68%. Evaluation of the skid resistance has been performed using the FAP (Friction After Polishing) test equipment also known as the Wehner/Schulze machine. Laboratory method enables to compare the skid resistance of different types of wearing course under specified conditions simulating polishing processes. In addition, macrotexture measurements were made on the surface of each specimen using the Elatexure laser profile. Analysis of variance showed that at significance level α = 0.05, aggregate graining compositions as well as the PSV have a significant influence on the obtained values of the friction coefficient μm of the tested EAC pavements. The highest values of the μm have been obtained for EAC with the lowest amount of coarse aggregates (compositions A). In these cases the resistance to polishing of the aggregate does not significantly affect the friction coefficients. This is related to the large areas of cement mortar between the exposed coarse grains. Based on the analysis of microscope images, it was observed that the coarse aggregates were not sufficiently exposed. It has been proved that PSV significantly affected the coefficient of friction in the case of compositions B and C. This is caused by large areas of exposed coarse aggregate. The best parameters were achieved for the EAC pavements

  17. Determining the fracture resistance of advanced SiC fiber reinforced SiC matrix composites

    International Nuclear Information System (INIS)

    Nozawa, T.; Katoh, Y.; Kishimoto, H.

    2007-01-01

    Full text of publication follows: One of the perceived advantages for highly-crystalline and stoichiometric silicon carbide (SiC) and SiC composites, e.g., advanced SiC fiber reinforced chemically-vapor-infiltrated (CVI) SiC matrix composites, is the retention of fast fracture properties after neutron irradiation at high-temperatures (∼1000 deg. C) to intermediate-doses (∼15 dpa). Accordingly, it has been clarified that the maximum allowable stress (or strain) limit seems unaffected in certain irradiation conditions. Meanwhile, understanding the mechanism of crack propagation from flaws, as potential weakest link to cause composite failure, is somehow lacking, despite that determining the strength criterion based on the fracture mechanics will eventually become important considering the nature of composites' fracture. This study aims to evaluate crack propagation behaviors of advanced SiC/SiC and to provide fundamentals on fracture resistance of the composites to define the strength limit for the practical component design. For those purposes, the effects of irreversible energies related to interfacial de-bonding, fiber bridging, and microcrack forming on the fracture resistance were evaluated. Two-dimensional SiC/SiC composites were fabricated by CVI or nano-infiltration and transient-eutectic-phase (NITE ) methods. Hi-Nicalon TM Type-S or Tyranno TM -SA fibers were used as reinforcements. In-plane mode-I fracture resistance was evaluated by the single edge notched bend technique. The key finding is the continuous Load increase with the crack growth for any types of advanced composites, while many studies specified the gradual load decrease for the conventional composites once the crack initiates. This high quasi-ductility appeared due primarily to high friction (>100 MPa) at the fiber/matrix interface using rough SiC fibers. The preliminary analysis based on the linear elastic fracture mechanics, which does not consider the effects of irreversible energy

  18. The effect of nylon nanofibers on the dynamic behaviour and the delamination resistance of GFRP composites

    Directory of Open Access Journals (Sweden)

    Garcia Cristobal

    2018-01-01

    Full Text Available Vibrations are responsible for a considerable number of accidents in aircrafts, bridges and other civil engineering structures. Therefore, there is a need to reduce the vibrations on structures made of composite materials. Delamination is a particularly dangerous failure mode for composite materials because delaminated composites can lose up to 60% of their strength and stiffness and still remain unchanged. One of the methods to suppress vibrations and preventing delamination is to incorporate nanofibers into the composite laminates. The aim of the present work is to investigate how nylon nanofibers affect the dynamic behaviour and delamination resistance of glass fibre reinforced polymer (GFRP composites. Experiments and numerical simulations using finite element modelling (FEM analysis are used to estimate the natural frequencies, the damping ratio and inter-laminar strength in GFRP composites with and without nylon nanofibers. It is found that the natural frequencies of the nylon nano-modified composites do not change significantly as compared to the traditional composites. However, nano-modified composites demonstrated a considerable increase in damping ratio and inter-laminar shear strength due to the incorporation of nylon nanofibers. This work contributes to the knowledge about the mechanical and dynamic properties of glass fibre reinforced polymer (GFRP composites with nylon nanofibers.

  19. Fatigue Resistant Bioinspired Composite from Synergistic Two-Dimensional Nanocomponents.

    Science.gov (United States)

    Wan, Sijie; Zhang, Qi; Zhou, Xiaohang; Li, Dechang; Ji, Baohua; Jiang, Lei; Cheng, Qunfeng

    2017-07-25

    Portable and wearable electronics require much more flexible graphene-based electrode with high fatigue life, which could repeatedly bend, fold, or stretch without sacrificing its mechanical properties and electrical conductivity. Herein, a kind of ultrahigh fatigue resistant graphene-based nanocomposite via tungsten disulfide (WS 2 ) nanosheets is synthesized by introducing a synergistic effect with covalently cross-linking inspired by the orderly layered structure and abundant interfacial interactions of nacre. The fatigue life of resultant graphene-based nanocomposites is more than one million times at the stress level of 270 MPa, and the electrical conductivity can be kept as high as 197.1 S/cm after 1.0 × 10 5 tensile testing cycles. These outstanding properties are attributed to the synergistic effect from lubrication of WS 2 nanosheets for deflecting crack propagation, and covalent bonding between adjacent GO nanosheets for bridging crack, which is verified by the molecular dynamics (MD) simulations. The WS 2 induced synergistic effect with covalent bonding offers a guidance for constructing graphene-based nanocomposites with high fatigue life, which have great potential for applications in flexible and wearable electronic devices, etc.

  20. Wear Resistance of TiC Reinforced Cast Steel Matrix Composite

    Directory of Open Access Journals (Sweden)

    Sobula S.

    2017-03-01

    Full Text Available Wear resistance of TiC-cast steel metal matrix composite has been investigated. Composites were obtained with SHSB method known as SHS synthesis during casting. It has been shown the differences in wear between composite and base cast steel. The Miller slurry machine test were used to determine wear loss of the specimens. The slurry was composed of SiC and water. The worn surface of specimens after test, were studied by SEM. Experimental observation has shown that surface of composite zone is not homogenous and consist the matrix lakes. Microscopic observations revealed the long grooves with SiC particles indented in the base alloy area, and spalling pits in the composite area. Due to the presence of TiC carbides on composite layer, specimens with TiC reinforced cast steel exhibited higher abrasion resistance. The wear of TiC reinforced cast steel mechanism was initially by wearing of soft matrix and in second stage by polishing and spalling of TiC. Summary weight loss after 16hr test was 0,14÷0,23 g for composite specimens and 0,90 g for base steel.

  1. Diffusion barrier coatings for high temperature corrosion resistance of advanced carbon/carbon composites

    International Nuclear Information System (INIS)

    Singh Raman, K.S.

    2000-01-01

    Carbon possesses an excellent combination of mechanical and thermal properties, viz., excellent creep resistance at temperatures up to 2400 deg C in non-oxidizing environment and a low thermal expansion coefficient. These properties make carbon a potential material for very high temperature applications. However, the use of carbon materials at high temperatures is considerably restricted due to their extremely poor oxidation resistance at temperatures above 400 deg C. The obvious choice for improving high temperature oxidation resistance of such materials is a suitable diffusion barrier coating. This paper presents an overview of recent developments in advanced diffusion- and thermal-barrier coatings for ceramic composites, with particular reference to C/C composites. The paper discusses the development of multiphase and multi-component ceramic coatings, and recent investigations on the oxidation resistance of the coated C/C composites. The paper also discusses the cases of innovative engineering solutions for traditional problems with the ceramic coatings, and the scope of intelligent processing in developing coatings for the C/C composites. Copyright (2000) AD-TECH - International Foundation for the Advancement of Technology Ltd

  2. Fatigue resistance of teeth restored with cuspal-coverage composite restorations.

    NARCIS (Netherlands)

    Fennis, W.M.M.; Kuijs, R.H.; Kreulen, C.M.; Verdonschot, N.J.J.; Creugers, N.H.J.

    2004-01-01

    PURPOSE: This study assessed the influence of palatal cuspal coverage on the in vitro fatigue resistance and failure mode of Class II resin composite restorations including replacement of the buccal cusp in premolars. MATERIALS AND METHODS: A master model was made of a maxillary premolar with an MOD

  3. Study of the relation between hydrated portland cement composition and leaching resistance

    NARCIS (Netherlands)

    Eijk, van R.J.; Brouwers, H.J.H.

    1998-01-01

    The present paper addresses cement compositions that have an optimal resistance against acid attack and hence, low leaching rates and optimal waste containment. To this end a shrinking core leaching model is used that describes the leaching of metals from a cement sample. This process is directly

  4. Study of hydrated Portland cement composition in regard to leaching resistance

    NARCIS (Netherlands)

    Eijk, van R.J.; Brouwers, H.J.H.

    1997-01-01

    The present paper addresses cement compositions that have an optimal resistance against acid attack and hence, low leaching rates and optimal waste containment. To this end a shrinking core leaching model is used that describes the leaching of metals from a cement sample. This process is directly

  5. In vitro fracture resistance of fiber reinforced cusp-replacing composite restorations.

    NARCIS (Netherlands)

    Fennis, W.M.M.; Tezvergil, A.; Kuijs, R.H.; Lassila, L.V.; Kreulen, C.M.; Creugers, N.H.J.; Vallittu, P.K.

    2005-01-01

    OBJECTIVES: To assess the fracture resistance and failure mode of fiber reinforced composite (FRC) cusp-replacing restorations in premolars. METHODS: Forty-five extracted sound upper premolars were randomly divided into three groups. Identical MOD cavities with simulated buccal cusp fracture and

  6. Decay resistance of wood-plastic composites reinforced with extracted or delignified wood flour

    Science.gov (United States)

    Rebecca E. Ibach; Yao Chen; Nicole M. Stark; Mandla A. Tshabalala; Yongming Fan; Jianmin Gao

    2014-01-01

    The moisture and decay resistance of wood-plastic composites (WPCs) reinforced with extracted or delignified wood flour (WF) was investigated. Three different extractions were preformed: toluene/ethanol (TE), acetone/water (AW), and hot water (HW). Delignification (DL) was performed using a sodium chlorite/acetic acid solution. All WPCs specimens were made with 50% by...

  7. Characterization of fatigue resistance in photochromic composite materials for 3D rewritable optical memory applications

    International Nuclear Information System (INIS)

    Samoylova, Elena; Dallari, William; Allione, Marco; Pignatelli, Francesca; Marini, Lara; Cingolani, Roberto; Diaspro, Alberto; Athanassiou, Athanassia

    2013-01-01

    Highlights: • Fatigue resistance of diarylethene–polymer composites was tested with optical absorption and fluorescence methods upon repetitive UV–VIS irradiation. • Significant differences in fatigue were found in different polymeric matrices and in one-photon and two-photon excitation experiments. • Several explanations for fatigue resistance of the composites are proposed based on the physico-chemical properties of the diarylethenes and polymeric matrices. -- Abstract: Fatigue resistance of the photochromic diarylethene molecules 1,2-bis[2-methylbenzo[b]thyophen-3-yl] -3,3,4,4,5,5-hexafluoro-1-cyclopentene embedded in three different acrylic polymers is studied upon multiple coloration–decoloration cycles. The resistance to photofatigue is found to be different in the three polymeric materials when one-photon excitation was used for the reversible photoconversion experiment. In particular, the photochromic molecules lose their photoisomerization ability faster if they are embedded in poly(methyl methacrylate) (PMMA) with respect to poly(ethyl methacrylate-co-methyl acrylate) (PEMMA) and poly(ethyl methacrylate) (PEMA). We propose several explanations based on the physico-chemical properties of the matrix and of the photochromic molecules. In the case of two-photon excitation, which is necessary for 3D optical writing, the fatigue resistance is found to be poorer than in the one-photon case. The accelerated photodegradation can be assigned to the non-linear nature of interaction between the polymeric composite material and light

  8. Characterization of fatigue resistance in photochromic composite materials for 3D rewritable optical memory applications

    Energy Technology Data Exchange (ETDEWEB)

    Samoylova, Elena, E-mail: Elena.Samoylova@physik.uni-muenchen.de [Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova (Italy); Dallari, William; Allione, Marco; Pignatelli, Francesca; Marini, Lara; Cingolani, Roberto; Diaspro, Alberto [Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova (Italy); Athanassiou, Athanassia, E-mail: athanassia.athanassiou@iit.it [Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova (Italy); Center for Biomolecular Nanotechnologies-Unile, Istituto Italiano di Tecnologia, via Barsanti, 73010 Arnesano, Lecce (Italy)

    2013-06-01

    Highlights: • Fatigue resistance of diarylethene–polymer composites was tested with optical absorption and fluorescence methods upon repetitive UV–VIS irradiation. • Significant differences in fatigue were found in different polymeric matrices and in one-photon and two-photon excitation experiments. • Several explanations for fatigue resistance of the composites are proposed based on the physico-chemical properties of the diarylethenes and polymeric matrices. -- Abstract: Fatigue resistance of the photochromic diarylethene molecules 1,2-bis[2-methylbenzo[b]thyophen-3-yl] -3,3,4,4,5,5-hexafluoro-1-cyclopentene embedded in three different acrylic polymers is studied upon multiple coloration–decoloration cycles. The resistance to photofatigue is found to be different in the three polymeric materials when one-photon excitation was used for the reversible photoconversion experiment. In particular, the photochromic molecules lose their photoisomerization ability faster if they are embedded in poly(methyl methacrylate) (PMMA) with respect to poly(ethyl methacrylate-co-methyl acrylate) (PEMMA) and poly(ethyl methacrylate) (PEMA). We propose several explanations based on the physico-chemical properties of the matrix and of the photochromic molecules. In the case of two-photon excitation, which is necessary for 3D optical writing, the fatigue resistance is found to be poorer than in the one-photon case. The accelerated photodegradation can be assigned to the non-linear nature of interaction between the polymeric composite material and light.

  9. "A New Class of Creep Resistant Oxide/Oxide Ceramic Matrix Composites"

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Mohit Jain, Dr. Ganesh Skandan, Prof. Roger Cannon, Rutgers University

    2007-03-30

    Despite recent progress in the development of SiC-SiC ceramic matrix composites (CMCs), their application in industrial gas turbines for distributed energy (DE) systems has been limited. The poor oxidation resistance of the non-oxide ceramics warrants the use of envrionmental barrier coatings (EBCs), which in turn lead to issues pertaining to life expectancy of the coatings. On the other hand, oxide/oxide CMCs are potential replacements, but their use has been limited until now due to the poor creep resistance at high temperatures, particularly above 1200 oC: the lack of a creep resistant matrix has been a major limiting factor. Using yttrium aluminum garnet (YAG) as the matrix material system, we have advanced the state-of-the-art in oxide/oxide CMCs by introducing innovations in both the structure and composition of the matrix material, thereby leading to high temperature matrix creep properties not achieved until now. An array of YAG-based powders with a unique set of particle characteristics were produced in-house and sintered to full density and compressive creep data was obtained. Aided in part by the composition and the microstructure, the creep rates were found to be two orders of magnitude smaller than the most creep resistant oxide fiber available commercially. Even after accounting for porosity and a smaller matrix grain size in a practical CMC component, the YAG-based matrix material was found to creep slower than the most creep resistant oxide fiber available commercially.

  10. Evaluation of the Impact Resistance of Various Composite Sandwich Beams by Vibration Tests

    Directory of Open Access Journals (Sweden)

    Amir Shahdin

    2011-01-01

    Full Text Available Impact resistance of different types of composite sandwich beams is evaluated by studying vibration response changes (natural frequency and damping ratio. This experimental works will help aerospace structural engineer in assess structural integrity using classification of impact resistance of various composite sandwich beams (entangled carbon and glass fibers, honeycomb and foam cores. Low velocity impacts are done below the barely visible impact damage (BVID limit in order to detect damage by vibration testing that is hardly visible on the surface. Experimental tests are done using both burst random and sine dwell testing in order to have a better confidence level on the extracted modal parameters. Results show that the entangled sandwich beams have a better resistance against impact as compared to classical core materials.

  11. Environment-friendly wood fibre composite with high bonding strength and water resistance

    Science.gov (United States)

    Ji, Xiaodi; Dong, Yue; Nguyen, Tat Thang; Chen, Xueqi; Guo, Minghui

    2018-04-01

    With the growing depletion of wood-based materials and concerns over emissions of formaldehyde from traditional wood fibre composites, there is a desire for environment-friendly binders. Herein, we report a green wood fibre composite with specific bonding strength and water resistance that is superior to a commercial system by using wood fibres and chitosan-based adhesives. When the mass ratio of solid content in the adhesive and absolute dry wood fibres was 3%, the bonding strength and water resistance of the wood fibre composite reached the optimal level, which was significantly improved over that of wood fibre composites without adhesive and completely met the requirements of the Chinese national standard GB/T 11718-2009. Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) characterizations revealed that the excellent performance of the binder might partly be due to the amide linkages and hydrogen bonding between wood fibres and the chitosan-based adhesive. We believe that this strategy could open new insights into the design of environment-friendly wood fibre composites with high bonding strength and water resistance for multifunctional applications.

  12. Resistance of Bonded Composite Restorations on Fractures of Endodontically Treated Teeth

    Directory of Open Access Journals (Sweden)

    AR Daneshkazemi

    2005-01-01

    Full Text Available Introduction: This study was performed to evaluate the effect of dentine bonding agents and Glass Ionomer cement beneath composite restorations and its resistance on fractures of endodontically treated teeth. Material and Methods: Forty sound maxillary teeth were selected; ten of them for positive control, and on the rest, RCT and MOD cavity preparations were done with standard methods. Then, the teeth were divided to four groups: 1-Sound teeth for positive control. 2-Prepared without any restoration for negative control. 3-Prepared and restored with Vitrabond(3M, USA, Single bond(3M, USA and Z100(3M, USA resin composite. 4-Prepared and restored by Single bond and Z100 resin composite. Specimens were subjected to compressive load by Instron 8502 until fracture occurred. Results: Group 1 showed the highest resistance to compressive forces followed by group 4,3&2 respectively. ANOVA, t test and Chi-square tests indicated significant difference between all the groups. Conclusion: Use of dentine bonding agents and resin composite increases resistance of endodontically treated teeth to fractures more than teeth restored with sandwich of glass ionomer cements, dentine bonding agents and resin composite.

  13. High compressive resistance drainage geo composites; Geocompuestos de drenaje de alta resistencia a compresion

    Energy Technology Data Exchange (ETDEWEB)

    Castelo Nolla, J.; Gutierrez Cuevas, J.

    2014-02-01

    There are several typologies of drainage geo composites available in the market which can be classified according to their structures as: cus pated, mono filaments, geo nets and those products formed by the combination of a draining blanket with a series of mini-pipes. Each one of them has its own range of compressive resistances. There are applications, such as are the new cells of landfills or mines and roads or railways over large embankments, where the pressure exerted on the geo composite exceeds the compressive resistance of the majority of these typologies. For all this applications, besides providing and adequate flow capacity, it must be ensured that the chosen typology is able to withstand the required loading without collapsing and guaranteeing an adequate factor of safety. This article will expose that, currently, the only typology of drainage geo composites that can bear these loadings while maintaining its drainage properties is the tri-planar geo net. (Author)

  14. Self-Diagnosis of Damage in Carbon Fiber Reinforced Composites Using Electrical Residual Resistance Measurement

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Ji Ho [KAERI, Daejeon (Korea, Republic of)

    2009-08-15

    The objective of this research was to develop a practical integrated approach using extracted features from electrical resistance measurements and coupled electromechanical models of damage, for in-situ damage detection and sensing in carbon fiber reinforced plastic(CFRP) composites. To achieve this objective, we introduced specific known damage (in terms of type, size, and location) into CFRP laminates and established quantitative relationships with the electrical resistance measurements. For processing of numerous measurement data, an autonomous data acquisition system was devised. We also established a specimen preparation procedure and a method for electrode setup. Coupon and panel CFRP laminate specimens with several known damage were tested. Coupon specimens with various sizes of artificial delaminations obtained by inserting Teflon film were manufactured and the resistance was measured. The measurement results showed that increase of delamination size led to increase of resistance implying that it is possible to sense the existence and size of delamination. A quasi-isotropic panel was manufactured and electrical resistance was measured. Then three different sizes of holes were drilled at a chosen location. The panel was prepared using the established procedures with six electrode connections on each side making a total of twenty-four electrodes. Vertical, horizontal, and diagonal pairs of electrodes were chosen and the resistance was measured. The measurement results showed the possibility of the established measurement system for an in-situ damage detection method for CFRP composite structures.

  15. The Impact of Morphology and Composition on the Resistivity and Oxidation Resistance of Metal Nanostructure Films

    Science.gov (United States)

    Stewart, Ian Edward

    Printed electronics, including transparent conductors, currently rely on expensive materials to generate high conductivity devices. Conductive inks for thick film applications utilizing inkjet, aerosol, and screen printing technologies are often comprised of expensive and rare silver particles. Thin film applications such as organic light emitting diodes (OLEDs) and organic photovoltaics (OPVs) predominantly employ indium tin oxide (ITO) as the transparent conductive layer which requires expensive and wasteful vapor deposition techniques. Thus an alternative to silver and ITO with similar performance in printed electronics warrants considerable attention. Copper nanomaterials, being orders of magnitude cheaper and more abundant than silver or indium, solution-coatable, and exhibiting a bulk conductivity only 6 % less than silver, have emerged as a promising candidate for incorporation in printed electronics. First, we examine the effect of nanomaterial shape on the conductivity of thick films. The inks used in such films often require annealing at elevated temperature in order to sinter the silver nanoparticles together and obtain low resistivities. We explore the change in morphology and resistivity that occurs upon heating thick films of silver nanowires (of two different lengths, Ag NWs), nanoparticles (Ag NPs), and microflakes (Ag MFs) deposited from water at temperatures between 70 and 400 °C. At the lowest temperatures, longer Ag NWs exhibited the lowest resistivity (1.8 x 10-5 O cm), suggesting that the resistivity of thick films of silver nanostructures is dominated by the contact resistance between particles. This result supported previous research showing that junction resistance between Ag NWs in thin film conductors also dominates optoelectronic performance. Since the goal is to replace silver with copper, we perform a similar analysis by using a pseudo-2D rod network modeling approach that has been modified to include lognormal distributions in length

  16. Repair Concepts as Design Constraints of a Stiffened Composite PRSEUS Panel

    Science.gov (United States)

    Przekop, Adam

    2012-01-01

    A design and analysis of a repair concept applicable to a stiffened thin-skin composite panel based on the Pultruded Rod Stitched Efficient Unitized Structure is presented. The concept is a bolted repair using metal components, so that it can easily be applied in the operational environment. The damage scenario considered is a midbay-to-midbay saw-cut with a severed stiffener, flange and skin. In a previous study several repair configurations were explored and their feasibility confirmed but refinement was needed. The present study revisits the problem under recently revised design requirements and broadens the suite of loading conditions considered. The repair assembly design is based on the critical tension loading condition and subsequently its robustness is verified for a pressure loading case. High fidelity modeling techniques such as mesh-independent definition of compliant fasteners, elastic-plastic material properties for metal parts and geometrically nonlinear solutions are utilized in the finite element analysis. The best repair design is introduced, its analysis results are presented and factors influencing the design are assessed and discussed.

  17. Fire protection concepts for Timber-Glass Composite façades

    Directory of Open Access Journals (Sweden)

    Schleicher Andreas

    2016-01-01

    The main objectives can be summarized as follows: Growth and densification in urban areas require the development of intelligent and resource-efficient building systems for “Smart Cities” of the future. By using timber-glass composites (TGC the primary energy demand of buildings can be reduced substantially. This research project examines the feasibility of applications of this new technology in multi-story and high-rise buildings. Critical aspects concerning fire protection such as flammability of timber elements, fire spread and failure of façade elements with bracing capacity will be analyzed. Different strategies will be developed in case studies and validated by structural analysis. Large scale mock ups of TGC façade elements will be checked on their suitability in fire tests. The findings of this research will lead to innovative fire safety concepts for building systems with TGC façades. Compliance with the high safety standards for multi-story buildings in urban areas like Vienna is one of the main objectives of this work. The adaptation of these fire safety concepts to the national standards of the neighboring countries will be continued subsequently. The gained knowledge should lead to further cooperation with companies for serial productions with TGC technology.

  18. Damage Tolerance of Resin Transfer Molded Composite Sandwich Constructions

    National Research Council Canada - National Science Library

    Vaidya, U

    1999-01-01

    .... The sandwich composite concepts considered in this study possessed the feasibility to improve the transverse stiffness, provide enhanced damage resistance/tolerance to impact and functionality...

  19. Recycled Aluminium Cans/Eggshell Composites: Evaluation of Mechanical and Wear Resistance Properties

    Directory of Open Access Journals (Sweden)

    J.O. Agunsoye

    2015-03-01

    Full Text Available Aluminium based metal matrix composites have been produced from recycled aluminium cans and 150µm sized eggshell particles using a stir cast process. The mechanical properties of the control and aluminium can/eggshell composites produced have been investigated. The microstructures of the aluminium can/eggshell composites were examined with the aids of Scanning Electron Microscope (SEM after the sample surfaces have been carefully prepared and etched with aqueous solution of 0.5 cm3 nitric acid. Micrographs revealed that there was a homogenous distribution of eggshell particles within the aluminium can matrix. An indication of effective stirring action during the melting process. The wear resistance was also investigated under different applied loads (6 to 14 N on an abrasive surface emery paper of grade 220. The results revealed an increase in Young’s modulus of elasticity and yield stress from 1,206.45 and 50.23 Mpa respectively of the cast aluminium can with 0 % eggshell particle to the maximum of 3,258.87and 73.2 MPa of aluminium can/12 % eggshell composites. The hardness values increased from 66.23 to 75.13 VN. There was a gradual increase in wear rate of the tested samples as the applied load increased. However, the wear resistance of the aluminium can/6 % eggshell and aluminium can/12 % eggshell composites increased significantly. Hence, recycling of aluminium cans and eggshells can be harnessed into development of useful engineering metal matrix composite materials.

  20. New Design Concept for an Excavator Arms by Using Composite Material

    Science.gov (United States)

    Solazzi, L.; Assi, A.; Ceresoli, F.

    2018-06-01

    The purpose of the present paper is to lightweight design an excavator arms, by using a different materials and in particular composite material. Specifically, the research is based on the study of a commercial excavator, by determining its geometry and analyzing the load conditions to which it is exposed. These are determined in relation to either the load diagram of the machine or the possible utilities of the excavator, such as the rotation of the machine. The materials used and implemented in the different analytical and numerical elaborations are classic construction steel S 355 (UNI EN 10025-3), high-resistance steel S 890 (UNI EN 10025-6), aluminum Al 6063 T6 (UNI EN 573-3) and the composite material made by carbon fiber and epoxy resin. The adopted constraints for the design of new arms with different materials, non-conventional for these applications, are numerous. The new solutions must present a safety factor either with respect to the yield tensile strength or to the critical load of buckling greater than or equal to the one determined for the excavator in its original geometrical conformation. Another criterion, which has heavily conditioned the geometry of the arms, was given by the fact that the developed solutions must present a very similar value of the maximum displacement in the different load conditions analyzed. A new geometry for arms made by composite material was developed. It was an elliptical conic section, instead of the classic rectangular section, in order to use the filament winding technological process. As for the adoption of the composite material, we focused on the study and the design of this material as long as the interaction with the extremities (made of aluminum) which are interfaced either with the link between the arms or with the elements of the hydraulic plant which serves for the arms movement. From the results developed, it emerges that the solution developed by adopting composite materials is the one that permits the

  1. Current concepts and systematic review of vascularized composite allotransplantation of the abdominal wall.

    Science.gov (United States)

    Berli, Jens U; Broyles, Justin M; Lough, Denver; Shridharani, Sachin M; Rochlin, Danielle; Cooney, Damon S; Lee, W P Andrew; Brandacher, Gerald; Sacks, Justin M

    2013-01-01

    Abdominal wall vascularized composite allotransplantation (AW-VCA) is a rarely utilized technique for large composite abdominal wall defects. The goal of this article is to systematically review the literature and current concepts of AW-VCA, outline the challenges ahead, and provide an outlook for the future. Systematic review of the literature was performed using MEDLINE, EMBASE, and PubMed to identify relevant articles discussing results of AW-VCA. Cadaver and animal studies were excluded from the systematic review, but selectively included in the discussion. The resultant five papers report their results on AW-VCA(Transplantation, 85, 2008, 1607; Am J Transplant, 7, 2007, 1304; Transplant Proc, 41, 2009, 521; Transplant Proc, 36, 2004, 1561; Lancet, 361, 2003, 2173). These papers represent the result of two study groups in which a total of 18 AW-VCA were performed in 17 patients. Two different operative approaches were used. Overall flap/graft survival was 88%. No mortality related to the transplant was reported. One cadaver study and two animal models were identified and separately presented (Transplant Proc, 43, 2011, 1701; Transplantation, 90, 2010, 1590; Journal of Surgical Research, 162, 2010, 314). Literature review reports AW-VCA is technically feasible with low morbidity and mortality. Functional outcomes are not reported and minimally considered. With advancements in vascularized composite allotransplantation research and decreasing toxicity of immunosuppression therapies and immunomodulatory regimens, AW-VCA can be applied in circumstances beyond conjunction with visceral transplantation. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  2. Piezoelectric and mechanical properties of fatigue resistant, self-healing PZT–ionomer composites

    International Nuclear Information System (INIS)

    James, N K; Lafont, U; Van der Zwaag, S; Groen, W A

    2014-01-01

    Piezoelectric ceramic–polymer composites with 0–3 connectivity were fabricated using lead zirconium titanate (PZT) powder dispersed in an ionomer (Zn ionomer) and its reference ethylene methacrylic acid copolymer (EMAA) polymer matrix. The PZT–Zn ionomer and PZT–EMAA composites were prepared by melt extrusion followed by hot pressing. The effects of poling conditions such as temperature, time and electric field on the piezoelectric properties of the composites were investigated. The experimentally observed piezoelectric charge coefficient and dielectric constant of the composites were compared with theoretical models. The results show that PZT–Zn ionomer composites have better piezoelectric properties compared to PZT–EMAA composites. The static and fatigue properties of the composites were investigated. The PZT–Zn ionomer composites were found to have excellent fatigue resistance even at strain levels of 4%. Due to the self-healing capabilities of the ionomer matrix, the loss of piezoelectric properties after high strain tensile cyclic loading could be partially recovered by thermal healing. (paper)

  3. Piezoelectric and mechanical properties of fatigue resistant, self-healing PZT-ionomer composites

    Science.gov (United States)

    James, N. K.; Lafont, U.; van der Zwaag, S.; Groen, W. A.

    2014-05-01

    Piezoelectric ceramic-polymer composites with 0-3 connectivity were fabricated using lead zirconium titanate (PZT) powder dispersed in an ionomer (Zn ionomer) and its reference ethylene methacrylic acid copolymer (EMAA) polymer matrix. The PZT-Zn ionomer and PZT-EMAA composites were prepared by melt extrusion followed by hot pressing. The effects of poling conditions such as temperature, time and electric field on the piezoelectric properties of the composites were investigated. The experimentally observed piezoelectric charge coefficient and dielectric constant of the composites were compared with theoretical models. The results show that PZT-Zn ionomer composites have better piezoelectric properties compared to PZT-EMAA composites. The static and fatigue properties of the composites were investigated. The PZT-Zn ionomer composites were found to have excellent fatigue resistance even at strain levels of 4%. Due to the self-healing capabilities of the ionomer matrix, the loss of piezoelectric properties after high strain tensile cyclic loading could be partially recovered by thermal healing.

  4. Fracture Resistance of Premolars Restored by Various Types and Placement Techniques of Resin Composites

    Directory of Open Access Journals (Sweden)

    Horieh Moosavi

    2012-01-01

    Full Text Available To verify the fracture resistance of premolars with mesioocclusodistal preparations restored by different resin composites and placement techniques. Sixty premolars were randomly divided into two groups based on type of composite resin: Filtek P60 or Nulite F, and then each group was separated into three subgroups: bulk, centripetal, and fiber insert according to the type of placement method (n=10. Single-bond adhesive system was used as composite bonding according to the manufacturer's instructions. Specimens were restored in Groups 1, 2, and 3 with Filtek P60 and in Groups 4, 5, and 6 with Nulite F. After being stored 24 hours at 37∘C, a 4 mm diameter steel sphere in a universal testing machine was applied on tooth buccal and lingual cusps at a cross-head speed of 5 mm/min until fracture occurred. Groups 3 and 6 showed higher fracture resistance than Groups 1, 2, 4, and 5. Among the placement techniques, the fiber insert method had a significant effect, but the type of composite was ineffective. The insertion technique in contrast to the type of material had a significant influence on the fracture resistance of premolar teeth.

  5. Insulin resistance, body composition, and fat distribution in obese children with nonalcoholic fatty liver disease.

    Science.gov (United States)

    Yang, Hye Ran; Chang, Eun Jae

    2016-01-01

    The aim of this study was to evaluate the influence of body composition, especially distribution of body fat, and insulin resistance on nonalcoholic fatty liver disease (NAFLD) in obese children. One hundred obese children (66 boys, 34 girls) with (n=60) and without NAFLD (n=40) were assessed. Anthropometry, laboratory tests, abdominal ultrasonography, and dual energy x-ray absorption metry (DXA) were evaluated in all subjects. Subject age and measurements of liver enzymes, γ- glutamyl transpeptidase (γGT), uric acid, high-density lipoprotein cholesterol, and insulin resistance were significantly different between the non-NAFLD group and NAFLD group. Body fat and trunk fat percentage were significantly different between the two groups (pfat percentage was not (p=0.683). Insulin resistance correlated significantly with body fat and trunk fat percentages, age, liver enzymes, γGT, and uric acid in obese children. Multiple logistic regression analysis indicated that insulin resistance and trunk fat percentage significantly affected the development of NAFLD in obese children. Body fat, especially abdominal fat, influences the development of insulin resistance and subsequent NAFLD in obese children. Therefore, body composition measurement using DXA, in conjunction with biochemical tests, may be beneficial in evaluating obese children with NAFLD.

  6. Effect of composition on corrosion resistance of high-alloy austenitic stainless steel weld metals

    International Nuclear Information System (INIS)

    Marshall, P.I.; Gooch, T.G.

    1993-01-01

    The corrosion resistance of stainless steel weld metal in the ranges of 17 to 28% chromium (Cr), 6 to 60% nickel (Ni), 0 to 9% molybdenum (Mo), and 0.0 to 0.37% nitrogen (N) was examined. Critical pitting temperatures were determined in ferric chloride (FeCl 3 ). Passive film breakdown potentials were assessed from potentiodynamic scans in 3% sodium chloride (NaCl) at 50 C. Potentiodynamic and potentiostatic tests were carried out in 30% sulfuric acid (H 2 SO 4 ) ar 25 C, which was representative of chloride-free acid media of low redox potential. Metallographic examination and microanalysis were conducted on the test welds. Because of segregation of alloying elements, weld metal pitting resistance always was lower than that of matching composition base steel. The difference increased with higher Cr, Mo, and N contents. Segregation also reduced resistance to general corrosion in H 2 SO 4 , but the effect relative to the base steel was less marked than with chloride pitting. Segregation of Cr, Mo, and N in fully austenitic deposits decreased as the Ni' eq- Cr' eq ratio increased. Over the compositional range studied, weld metal pitting resistance was dependent mainly on Mo content and segregation. N had less effect than in wrought alloys. Both Mo and N enhanced weld metal corrosion resistance in H 2 SO 4

  7. Co nanoparticles induced resistive switching and magnetism for the electrochemically deposited polypyrrole composite films.

    Science.gov (United States)

    Xu, Zedong; Gao, Min; Yu, Lina; Lu, Liying; Xu, Xiaoguang; Jiang, Yong

    2014-10-22

    The resistive switching behavior of Co-nanoparticle-dispersed polypyrrole (PPy) composite films is studied. A novel design method for resistive random access memory (ReRAM) is proposed. The conducting polymer films with metal nanocrystal (NC)-dispersed carbon chains induce the spontaneous oxidization of the conducting polymer at the surface. The resistive switching behavior is achieved by an electric field controlling the oxygen ion mobility between the metal electrode and the conducting polymer film to realize the mutual transition between intrinsic conduction (low resistive state) and oxidized layer conduction (high resistive state). Furthermore, the formation process of intrinsic conductive paths can be effectively controlled in the conducting polymer ReRAM using metal NCs in films because the inner metal NCs induce electric field lines converging around them and the intensity of the electric field at the tip of NCs can greatly exceed that of the other region. Metal NCs can also bring new characteristics for ReRAM, such as magnetism by dispersing magnetic metal NCs in polymer, to obtain multifunctional electronic devices or meet some special purpose in future applications. Our works will enrich the application fields of the electromagnetic PPy composite films and present a novel material for ReRAM devices.

  8. Study of Thermal Fatigue Resistance of a Composite Coating Made by a Vacuum Fusion Sintering Method

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Thermal fatigue behavior of a Ni-base alloy chromium carbide composite coating made by a vacuum fusion sintering method are discussed. Results show that thermal fatigue behavior is associated with cyclic upper temperature and coating thickness. As the thickness of the coating decreases, the thermal fatigue resistance increases. The thermal fatigue resistance cuts down with the thermal cyclic upper temperature rising. The crack growth rate decreases with the increase in cyclic number until crack arrests. Thermal fatigue failure was not found along the interface of the coating/matrix. The tract of thermal fatigue crack cracks along the interfaces of phases.

  9. Nitrous Oxide for Treatment-Resistant Major Depression: A Proof-of-Concept Trial.

    Science.gov (United States)

    Nagele, Peter; Duma, Andreas; Kopec, Michael; Gebara, Marie Anne; Parsoei, Alireza; Walker, Marie; Janski, Alvin; Panagopoulos, Vassilis N; Cristancho, Pilar; Miller, J Philip; Zorumski, Charles F; Conway, Charles R

    2015-07-01

    N-methyl-D-aspartate receptor antagonists, such as ketamine, have rapid antidepressant effects in patients with treatment-resistant depression (TRD). We hypothesized that nitrous oxide, an inhalational general anesthetic and N-methyl-D-aspartate receptor antagonist, may also be a rapidly acting treatment for TRD. In this blinded, placebo-controlled crossover trial, 20 patients with TRD were randomly assigned to 1-hour inhalation of 50% nitrous oxide/50% oxygen or 50% nitrogen/50% oxygen (placebo control). The primary endpoint was the change on the 21-item Hamilton Depression Rating Scale (HDRS-21) 24 hours after treatment. Mean duration of nitrous oxide treatment was 55.6 ± 2.5 (SD) min at a median inspiratory concentration of 44% (interquartile range, 37%-45%). In two patients, nitrous oxide treatment was briefly interrupted, and the treatment was discontinued in three patients. Depressive symptoms improved significantly at 2 hours and 24 hours after receiving nitrous oxide compared with placebo (mean HDRS-21 difference at 2 hours, -4.8 points, 95% confidence interval [CI], -1.8 to -7.8 points, p = .002; at 24 hours, -5.5 points, 95% CI, -2.5 to -8.5 points, p nitrous oxide and placebo, p nitrous oxide compared with one patient (5%) and none after placebo (odds ratio for response, 4.0, 95% CI, .45-35.79; OR for remission, 3.0, 95% CI, .31-28.8). No serious adverse events occurred; all adverse events were brief and of mild to moderate severity. This proof-of-concept trial demonstrated that nitrous oxide has rapid and marked antidepressant effects in patients with TRD. Copyright © 2015 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  10. Dextromethorphan/quinidine pharmacotherapy in patients with treatment resistant depression: A proof of concept clinical trial.

    Science.gov (United States)

    Murrough, James W; Wade, Elizabeth; Sayed, Sehrish; Ahle, Gabriella; Kiraly, Drew D; Welch, Alison; Collins, Katherine A; Soleimani, Laili; Iosifescu, Dan V; Charney, Dennis S

    2017-08-15

    At least one-third of patients with major depressive disorder (MDD) have treatment-resistant depression (TRD), defined as lack of response to two or more adequate antidepressant trials. For these patients, novel antidepressant treatments are urgently needed. The current study is a phase IIa open label clinical trial examining the efficacy and tolerability of a combination of dextromethorphan (DM) and the CYP2D6 enzyme inhibitor quinidine (Q) in patients with TRD. Dextromethorphan acts as an antagonist at the glutamate N-methyl-d-aspartate (NMDA) receptor, in addition to other pharmacodynamics properties that include activity at sigma-1 receptors. Twenty patients with unipolar TRD who completed informed consent and met all eligibility criteria we enrolled in an open-label study of DM/Q up to 45/10mg by mouth administered every 12h over the course of a 10-week period, and constitute the intention to treat (ITT) sample. Six patients discontinued prior to study completion. There was no treatment-emergent suicidal ideation, psychotomimetic or dissociative symptoms. Montgomery-Asberg Depression Rating Scale (MADRS) score was reduced from baseline to the 10-week primary outcome (mean change: -13.0±11.5, t 19 =5.0, p<0.001), as was QIDS-SR score (mean change: -5.9±6.6, t 19 =4.0, p<0.001). The response and remission rates in the ITT sample were 45% and 35%, respectively. Open-label, proof-of-concept design. Herein we report acceptable tolerability and preliminary efficacy of DM/Q up to 45/10mg administered every 12h in patients with TRD. Future larger placebo controlled randomized trials in this population are warranted. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Utilization of composite fecal samples for detection of anthelmintic resistance in gastrointestinal nematodes of cattle.

    Science.gov (United States)

    George, Melissa M; Paras, Kelsey L; Howell, Sue B; Kaplan, Ray M

    2017-06-15

    Recent reports indicate that anthelmintic resistance in gastrointestinal nematodes of cattle is becoming increasingly prevalent worldwide. Presently, the fecal egg count reduction test (FECRT) is the only means available for detection of resistance to anthelmintics in cattle herds at the farm level. However, the FECRT is labor and cost intensive, and consequently is only rarely performed on cattle farms unless for research purposes. If costs could be reduced, cattle producers might be more likely to pursue drug resistance testing on their farms. One approach to reducing the cost of the FECRT, is the use of composite fecal samples for performing fecal egg counts (FEC), rather than conducting FEC on fecal samples from 15 to 20 individual animals. In this study FECRT were performed on 14 groups of cattle using both individual and composite FEC methods To measure how well the results of composite sampling reproduce those of individual sampling, Lin's Concordance Correlation Coefficient was utilized to describe both the linear relationship between methods and the slope and y-intercept of the line relating the data sets. There was little difference between the approaches with 98% agreement in mean FEC found between methods Mean FEC based on individual counts ranged between 0 and 670.6 eggs per gram of feces, indicating that the results of this study are applicable to a wide range of FEC levels. Standard error of the mean FEC and range of FEC are reported for each group prior to and following treatment to describe the variability of the data set. There was greater than 95% agreement in drug efficacy between individual and composite sampling methods, demonstrating composite sampling is appropriate to evaluate drug efficacy. Notably, for all groups tested the efficacy calculated by composite sampling was within the 95% confidence interval for efficacy calculated using individual sampling. The use of composite samples was shown to reduce the number of FEC required by 79

  12. Wettability and interface considerations in advanced heat-resistant Ni-base composites

    International Nuclear Information System (INIS)

    Asthana, R.; Mileiko, S.T.; Sobczak, N.

    2006-01-01

    Oxide fiber-reinforced Ni-base composites have long been considered as attractive heat-resistant materials. After several decades of active research, however, interest in these materials began to decline around mid-1990's due chiefly to 1) a lack of manufacturing technology to grow inexpensive single-crystal oxide fibers to be used in structural composites, and 2) fiber strength loss during processing due to chemical interactions with reactive solutes in the matrix. The cost disadvantage has been mitigated to a large extent by the development of innovative fiber fabrication processes such as the Internal Crystallization Method (ICM) that produces monocrystalline oxide fibers in a cost-effective manner. Fiber strength loss has been an equally restrictive issue but recent work has shown that it may be possible to design creep-resistant composites even when fiber surface reconstruction from chemical interactions has degraded the strength of extracted fibers tested outside the matrix. The key issue is the optimization of the composite- and interface structure. Reaction-formed defects may be healed by the matrix (or a suitable coating material) so that the fiber residing in the matrix may exhibit diminished sensitivity to flaws as compared to fibers extracted from the matrix and tested in isolation of the matrix. Generally, the Ni-base/Al 2 O 3 composites exhibit acceptable levels of wettability and interface strength (further improved with the aid of reactive solutes), which are required for elevated-temperature creep-resistance. In order to harness the full potential of these composites, the quality of the interface as manifested in the fiber/matrix wettability, interface composition, interphase morphology, and interface strength must be designed. We identify key issues related to the measurement of contact angle, interface strength, and chemical and structural properties at the fiber/matrix interface in the Ni/alumina composites, and present the current state-of the

  13. The influence of modification of elastomer compositions in polyethylene oxides on their resistance to mineral oils

    Directory of Open Access Journals (Sweden)

    E. P. Uss

    2017-01-01

    Full Text Available The influence of modifying of elastomer compositions based on nitrile rubber in the medium of low molecular weight polyethylene oxide on resistance of rubbers to liquid aggressive mediawas studied. Standard hydrocarbon oils – oil ASTM №1 and ASTM №3, having a constant chemical composition and properties, were used as aggressive fluids. Resistance of elastomer compositions to standard oil was evaluated by change in weight, volume and relative compression set after keeping the samples in these oils at elevated temperatures. The influence of aggressive environment on the degree of swelling and the value of compression set of compositions modified in polyethylene oxides medium was established. It has been shown that the mass/volume of modified rubbers during aging in oil ASTM №1 reduced to a lesser degree compared to unmodified samples, which is probably due to the influence of low molecular weight polyethylene oxides for the formation of vulcanizates structure. At the same time exposure to oil ASTM №3 of elastomer compositions increases the degree of swelling of modified rubber more than unmodified, which can be due to destruction by the action of aggressive medium additional intermolecular bonds between macromolecules of polyethylene oxide and rubber, resulting in increased flexibility of the elastomeric matrix segments. It revealed that modification of rubbers in low molecular weightpolyethylene oxides facilitates preparation of rubber with low compression set after aging in standard oils at elevated temperatures.

  14. Body composition influenced by progressive elastic band resistance exercise of sarcopenic obesity elderly women: a pilot randomized controlled trial.

    Science.gov (United States)

    Huang, Shih-Wei; Ku, Jan-Wen; Lin, Li-Fong; Liao, Chun-De; Chou, Lin-Chuan; Liou, Tsan-Hon

    2017-08-01

    Sarcopenia involves age-related decreases in muscle strength and muscle mass, leading to frailty and disability in elderly people. When combined with obesity, it is defined as sarcopenic obesity (SO), which can result in more functional limitations and metabolic disorders than either disorder alone. The aim of this study was to investigate body composition changes after elastic band resistance training in elderly women with SO. Randomized single-blinded (assessor blinded) controlled pilot trial. Academic medical center. Thirty-five elderly (>60 years old) women with SO. This pilot randomized controlled trial focused on elderly women with SO. The study group underwent progressive elastic band resistance training for 12 weeks (3 times per week). The control group received only a 40-minute lesson about the exercise concept. Dual-energy X-ray absorptiometry was performed before and after intervention to evaluate body composition. Mann-Whitney U and Wilcoxon signed rank tests were used to analyze the differences within and between these groups. In total, 35 elderly women with SO were enrolled and divided into study (N.=18) and control groups (N.=17). No difference was observed in age, biochemical parameters, or Body Mass Index between both groups. After the intervention, the fat proportion of body composition in the right upper extremity (P=0.03), left upper extremity (P=0.04), total fat (P=0.035), and fat percentage (P=0.012) had decreased, and bone mineral density (BMD) (P=0.026), T-score (P=0.028), and Z-score (P=0.021) had increased in the study group. Besides, statistical difference was observed in outcome measurements of right upper extremity (P=0.013), total fat (P=0.023), and fat percentage (P=0.012) between the groups. Our study demonstrated that progressive elastic band resistance exercise can reduce fat mass and increase BMD in elderly women with SO, and that this exercise program is feasible for this demographic. Additional studies with larger sample sizes

  15. Wear resistance and electrical properties of functionally graded epoxy-resin/silica composites

    International Nuclear Information System (INIS)

    Rihan, Y. A.; Abd El-Bary, B.

    2012-12-01

    In this paper graded Silica/Epoxy composite fabricated by controlled mold filling to obtain a stepwise graded structure. The generated graded structure was controlled by the w 1% content of silica particulates of size range from (45 μm-250 μm). Microstructural characterization was conducted using Scanning Electron Microscope (SEM). Electrical properties were conducted in High Voltage-Lab using Sphere-Plate Electrode System and Insulating resistance equipment s. Wear characteristics were studied using Block-on-Ring wear testing machine for the different layers of the graded silica/epoxy composites, The prepared materials are used as coating materials for the floors of chemical laboratories. (Author)

  16. Dependence of Seebeck coefficient on a load resistance and energy conversion efficiency in a thermoelectric composite

    International Nuclear Information System (INIS)

    Yamashita, Osamu; Odahara, Hirotaka; Ochi, Takahiro; Satou, Kouji

    2007-01-01

    The thermo-emf ΔV and current ΔI generated by imposing the alternating temperature gradients (ATG) at a period of T and the steady temperature gradient (STG) on a thermoelectric (TE) composite were measured as a function of t, where t is the lapsed time and T was varied from 60 to or ∞ s. The STG and ATG were produced by imposing steadily and alternatively a source voltage V in the range from 1.0 to 4.0 V on two Peltier modules sandwiching a composite. ΔT, ΔV, ΔI and V P oscillate at a period T and their waveforms vary significantly with a change of T, where ΔV and V P are the voltage drops in a load resistance R L and in resistance R P of two modules. The resultant Seebeck coefficient |α| = |ΔV|/ΔT of a composite under the STG was found to be expressed as |α| = |α 0 |(1 - R comp /R T ), where R T is the total resistance of a circuit for measuring the output signals and R comp is the resistance of a composite. The effective generating power ΔW eff has a local maximum at T = 960 s for the p-type composite and at T = 480 s for the n-type one. The maximum energy conversion efficiency η of the p- and n-type composites under the ATG produced by imposing a voltage of 4.0 V at an optimum period were 0.22 and 0.23% at ΔT eff = 50 K, respectively, which are 42 and 43% higher than those at ΔT = 42 K under the STG. These maximum η for a TE composite sandwiched between two Peltier modules, were found to be expressed theoretically in terms of R P , R T , R L , α P and α, where α P and α are the resultant Seebeck coefficients of Peltier modules and a TE composite

  17. Muscle function and body composition profile in adolescents with restrictive anorexia nervosa: Does resistance training help?

    OpenAIRE

    Fernández del Valle, María; Larumbe Zabala, Eneko; Morandé Lavín, Gonzalo; Pérez Ruiz, Margarita

    2016-01-01

    The aim of this study was to analyze the effects of short-term resistance training on the body composition profile and muscle function in a group of Anorexia Nervosa restricting type (AN-R) patients. The sample consisted of AN-R female adolescents (12.8 ± 0.6 years) allocated into the control and intervention groups (n¼18 each). Body composition and relative strength were assessed at baseline, after 8 weeks and 4 weeks following the intervention. Body mass index (BMI) increased throughout...

  18. Thermal shock resistances of a bonding material of C/C composite and copper

    International Nuclear Information System (INIS)

    Kurumada, Akira; Oku, Tatsuo; Kawamata, Kiyohiro; Motojima, Osamu; Noda, Nobuaki; McEnaney, B.

    1997-01-01

    The purpose of this study is to contribute to the development and the safety design of plasma facing components for fusion reactor devices. We evaluated the thermal shock resistance and the thermal shock fracture toughness of a bonding material which was jointed a carbon-fiber-reinforced carbon composite (C/C composite) to oxygen-free copper. We also examined the microstructures of the bonding layers using a scanning electron microscope before and after thermal shock tests. The bonding material did not fracture during thermal shock tests. However, thermal cracks and delamination cracks were observed in the bonding layers. (author)

  19. Insulin resistance, exercise capacity and body composition in subjects with two hypertensive parents

    DEFF Research Database (Denmark)

    Andersen, U B; Dige-Petersen, H; Ibsen, H

    1999-01-01

    OBJECTIVE: To study insulin resistance in subjects with strong genetic predisposition to essential hypertension, compared with non-disposed subjects. SUBJECTS: Thirty normotensive subjects aged 18-35 years whose parents both had essential hypertension, and 30 age- and sex matched subjects whose...... correlated to abdominal fat mass but not to insulin sensitivity. CONCLUSION: Subjects with a strong genetic predisposition to essential hypertension had increased diastolic blood pressure compared with subjects with normotensive parents, but they were not insulin resistant. This may be due to the subjects...... for the difference between the means; -0.5; -7.9), but the insulin sensitivity index was similar: 312 versus 362 I(2) min(-1) pmol(-1) kg(-1) (28; -129). The two groups were similar in terms of body composition, exercise capacity and composition of usual diet. Resting and 24-h diastolic blood pressures were...

  20. Effect of Processing Conditions on Fracture Resistance and Cohesive Laws of Binderfree All-Cellulose Composites

    DEFF Research Database (Denmark)

    Goutianos, Stergios; Arévalo, R.; Sørensen, Bent F.

    2014-01-01

    molecules during the drying process. Defibrilation of the raw cellulose material is done in wet medium in a paper-like process. Panels with different refining time were tested and it was found than an increase in fibre fibrillation results in a lower fracture resistance. © 2014 Springer Science......The fracture properties of all-cellulose composites without matrix were studied using Double Cantilever Beam (DCB) sandwich specimens loaded with pure monotonically increasing bending moments, which give stable crack growth. The experiments were conducted in an environmental scanning electron...... microscope to a) perform accurate measurements of both the fracture energy for crack initiation and the fracture resistance and b) observe the microscale failure mechanisms especially in the the wake of the crack tip. Since the mechanical behaviour of the all-cellulose composites was non-linear, a general...

  1. A new concept in polymeric thin-film composite nanofiltration membranes with antibacterial properties.

    Science.gov (United States)

    Mollahosseini, Arash; Rahimpour, Ahmad

    2013-01-01

    A new, thin film, biofouling resistant, nanofiltration (NF) membrane was fabricated with two key characteristics, viz. a low rate of silver (Ag) release and long-lasting antibacterial properties. In the new approach, nanoparticles were embedded completely in a polymeric thin-film layer. A comparison was made between the new thin-film composite (TFC), NF membrane and thin-film nanocomposite (TFN), and antibacterial NF membranes. Both types of NF membrane were fabricated by interfacial polymerization on a polysulphone sublayer using m-phenylenediamine and trimesoyl chloride as an amine monomer and an acid chloride monomer, respectively. Energy dispersive X-ray (EDX) microanalysis demonstrated the presence of Ag nanoparticles. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to study the cross-sectional and surface morphological properties of the NF membranes. Permeability and salt rejection were tested using a dead-end filtration cell. Ag leaching from the membranes was measured using inductively coupled mass spectrometry (ICP-MS). Morphological studies showed that the TFC NF membranes had better thin-film formation (a more compact structure and a smoother surface) than TFN NF membranes. Performance experiments on TFC NF membranes revealed that permeability was good, without sacrificing salt rejection. The antibacterial properties of the fabricated membranes were tested using the disk diffusion method and viable plate counts. The antibiofouling properties of the membranes were examined by measuring the quantity of bacterial cells released from the biofilm formed (as a function of the amount of biofilm present). A more sensitive surface was observed compared to that of a typical antibacterial NF membrane. The Ag leaching rates were low, which will likely result in long-lasting antibacterial and biofouling resistant properties.

  2. The correlation of grain boundary composition in irradiated stainless steel with IASCC resistance

    International Nuclear Information System (INIS)

    Jacobs, A.J.; Wozadlo, G.P.; Nakata, K.; Kasahara, S.; Okada, T.; Kawano, S.; Suzuki, S.

    1993-01-01

    Scanning transmission electron microscopy (STEMP) analysis were conducted on a group of irradiated Type-316 stainless steels (SS), in an continuing effort to correlate grain boundary composition with IASCC resistance. The latter property was measured by either one of two means: an in-reactor (boiling water reactor) swelling-mandrel-type test or a laboratory constant extension rate tensile (CERT) test. Possibly because of their basically different nature, the two types of test yielded different correlations with the STEM results. The in-reactor results showed two regimes, one in which IASCC resistance remained essentially unchanged with increasing radiation-induced segregation/depletion (RIS), and another in which IASCC resistance increased with decreasing RIS. The CERT test results, on the other hand, showed a monotonic increase in IASCC resistance with decreasing RIS, with a transition range of RIS in which IASCC resistance was very high or very low. It appeared from the two sets of results that in the reactor environment, a low degree of RIS was necessary but not sufficient for high IASCC resistance, and in the laboratory environment, a low degree of RIS was necessary and sufficient

  3. Generation of composite Persea americana (Mill.) (avocado) plants: A proof-of-concept-study.

    Science.gov (United States)

    Prabhu, S Ashok; Ndlovu, Buyani; Engelbrecht, Juanita; van den Berg, Noëlani

    2017-01-01

    Avocado (Persea americana (Mill.)), an important commercial fruit, is severely affected by Phytophthora Root Rot in areas where the pathogen is prevalent. However, advances in molecular research are hindered by the lack of a high-throughput transient transformation system in this non-model plant. In this study, a proof-of-concept is demonstrated by the successful application of Agrobacterium rhizogenes-mediated plant transformation to produce composite avocado plants. Two ex vitro strategies were assessed on two avocado genotypes (Itzamna and A0.74): In the first approach, 8-week-old etiolated seedlings were scarred with a sterile hacksaw blade at the base of the shoot, and in the second, inch-long incisions were made at the base of the shoot (20-week-old non-etiolated plants) with a sterile blade to remove the cortical tissue. The scarred/wounded shoot surfaces were treated with A. rhizogenes strains (K599 or ARqua1) transformed with or without binary plant transformation vectors pRedRootII (DsRed1 marker), pBYR2e1-GFP (GFP- green fluorescence protein marker) or pBINUbiGUSint (GUS- beta-glucuronidase marker) with and without rooting hormone (Dip 'N' Grow) application. The treated shoot regions were air-layered with sterile moist cocopeat to induce root formation. Results showed that hormone application significantly increased root induction, while Agrobacterium-only treatments resulted in very few roots. Combination treatments of hormone+Agrobacterium (-/+ plasmids) showed no significant difference. Only the ARqua1(+plasmid):A0.74 combination resulted in root transformants, with hormone+ARqua1(+pBINUbiGUSint) being the most effective treatment with ~17 and 25% composite plants resulting from strategy-1 and strategy-2, respectively. GUS- and GFP-expressing roots accounted for less than 4 and ~11%, respectively, of the total roots/treatment/avocado genotype. The average number of transgenic roots on the composite plants was less than one per plant in all treatments

  4. Highly stretchable resistive pressure sensors using a conductive elastomeric composite on a micropyramid array.

    Science.gov (United States)

    Choong, Chwee-Lin; Shim, Mun-Bo; Lee, Byoung-Sun; Jeon, Sanghun; Ko, Dong-Su; Kang, Tae-Hyung; Bae, Jihyun; Lee, Sung Hoon; Byun, Kyung-Eun; Im, Jungkyun; Jeong, Yong Jin; Park, Chan Eon; Park, Jong-Jin; Chung, U-In

    2014-06-04

    A stretchable resistive pressure sensor is achieved by coating a compressible substrate with a highly stretchable electrode. The substrate contains an array of microscale pyramidal features, and the electrode comprises a polymer composite. When the pressure-induced geometrical change experienced by the electrode is maximized at 40% elongation, a sensitivity of 10.3 kPa(-1) is achieved. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Erosion resistance and adhesion of composite metal/ceramic coatings produced by plasma spraying

    OpenAIRE

    Ramm , D.; Hutchings , I.; Clyne , T.

    1993-01-01

    Ceramic coatings can exhibit greater erosion resistance than most metallic coatings. Such coatings are conveniently produced by thermal spraying. Unfortunately, thermally sprayed ceramic coatings often exhibit poor adhesion, partly as a consequence of the development of residual stresses during spraying and subsequent cooling. Composite coatings have been studied using aluminium/alumina deposits on steel substrates. The incorporation of ceramics within a ductile matrix has potential for sharp...

  6. Rhodium and Hafnium Influence on the Microstructure, Phase Composition, and Oxidation Resistance of Aluminide Coatings

    OpenAIRE

    Maryana Zagula-Yavorska; Małgorzata Wierzbińska; Jan Sieniawski

    2017-01-01

    A 0.5 μm thick layer of rhodium was deposited on the CMSX 4 superalloy by the electroplating method. The rhodium-coated superalloy was hafnized and aluminized or only aluminized using the Chemical vapour deposition method. A comparison was made of the microstructure, phase composition, and oxidation resistance of three aluminide coatings: nonmodified (a), rhodium-modified (b), and rhodium- and hafnium-modified (c). All three coatings consisted of two layers: the additive layer and the interdi...

  7. Multi-scale approach to the mechanical behavior of SiC/SiC composites: the concept of mini-composite

    International Nuclear Information System (INIS)

    Lamon, J.

    2007-01-01

    Full text of publication follows: The concept of composite materials is very powerful, since one can tailor the properties with respect to end use applications, through a sound combination of constituents, including fibre, matrix and inter-phases. Ceramic matrix composites (CMCs) are at the forefront of advanced materials technology because of their light weight, high strength and toughness, high temperature capabilities and graceful failure under loading. This key behaviour is achieved by proper design of the fiber/matrix interface which helps in arresting and deflecting the cracks formed in the brittle matrix under load and preventing the early failure of the fiber arrangement. Ceramic matrix composites are considered as enabling technology for advanced aero-propulsion, space power, aerospace vehicles, space structures, ground transportation, as well as nuclear and chemical industries. During the last 30 years, tremendous progress has been made in the development of CMCs. Much research work has been conducted by LCTS on those SiC/SiC composites made via Chemical Vapor Infiltration. A multi-scale approach to mechanical behaviour has been developed. This multi-scale approach is aimed at relating the mechanical behaviour at macroscopic scale to constituent properties. It involves experiments and modelling. It allows chemical effects to be introduced in the models of mechanical behaviour. The present paper discusses the main features of the mechanical behaviour of textile SiC/SiC composites. These features are related to composite microstructure, properties of constituents (fibers, matrix and interphase) and fiber arrangement. Relationships between properties at different scales are established. Then the mini-composite concept is addressed. This concept is very powerful for composite design and investigation. Mini-composites consist of unidirectional composites reinforced by multi-filament tows. Mini-composites represent the mesoscale of textile composites. In

  8. Fracture resistance of class IV fiber-reinforced composite resin restorations: An in vitro study

    Directory of Open Access Journals (Sweden)

    P S Praveen Kumar

    2017-01-01

    Full Text Available Objectives: The aim of this study was to evaluate fracture resistance of incisal edge fractures (Class IV restored with a Glass Fiber-reinforced Composite (FRC. Materials and Methods: Twenty-four extracted sound maxillary central incisors were randomly divided into two groups. Group I (control contained untreated teeth. Samples in experimental groups II were prepared by cutting the incisal (one-third part of the crown horizontally and was subjected to enamel preparations, then restored with a Glass FRC. Fracture resistance was evaluated as Newton's for samples tested in a Hounsfield universal testing machine. Failure modes were examined microscopically. Results: Mean peak failure load (Newton's observed in Glass Fiber-reinforced Nanocomposite was 863.50 ± 76.12. The experimental group showed similar types of failure modes with the majority occurring as cohesive and mixed type. 58% of the teeth in Glass FRC group fractured below the cementoenamel junction. Conclusion: Using Fiber reinforced composite substructure under conventional composites in Class IV restorations, the fracture resistance of the restored incisal edge could be increased.

  9. A Damage Resistance Comparison Between Candidate Polymer Matrix Composite Feedline Materials

    Science.gov (United States)

    Nettles, A. T

    2000-01-01

    As part of NASAs focused technology programs for future reusable launch vehicles, a task is underway to study the feasibility of using the polymer matrix composite feedlines instead of metal ones on propulsion systems. This is desirable to reduce weight and manufacturing costs. The task consists of comparing several prototype composite feedlines made by various methods. These methods are electron-beam curing, standard hand lay-up and autoclave cure, solvent assisted resin transfer molding, and thermoplastic tape laying. One of the critical technology drivers for composite components is resistance to foreign objects damage. This paper presents results of an experimental study of the damage resistance of the candidate materials that the prototype feedlines are manufactured from. The materials examined all have a 5-harness weave of IM7 as the fiber constituent (except for the thermoplastic, which is unidirectional tape laid up in a bidirectional configuration). The resin tested were 977-6, PR 520, SE-SA-1, RS-E3 (e-beam curable), Cycom 823 and PEEK. The results showed that the 977-6 and PEEK were the most damage resistant in all tested cases.

  10. Towards mechanisms-guided resistivity-based monitoring of damage evolution in laminated composites

    KAUST Repository

    Lubineau, Gilles

    2013-04-05

    A convenient health monitoring technique for detecting degradation in laminated composite is to monitor the change of electrical resistance along multiple conduction paths within the structure. Yet, the relations between the global modification of resistivity and the exact underlying damage map is still unclear that makes diffcult to interpret these nondestructive-testing results. The challenge is then to be able to reconstruct from these global observation the underlying damage map. This is even more diffcult due to the numerous underlying damage mechanisms that can take place either at the inter laminar of intra laminar level. This paper intends to provide some preliminary insights about strategies to recover the damage state based only on global measurements. We focus here on transverse cracking detection. We introduce the homogenization process that defines at the meso scale an equivalent homogeneous ply that is energetically equivalent to the cracked one. This can be used as a first tool to reconstruct damage maps based on global resistivity measurements.

  11. Fatigue resistance and microleakage of CAD/CAM ceramic and composite molar crowns.

    Science.gov (United States)

    Kassem, Amr S; Atta, Osama; El-Mowafy, Omar

    2012-01-01

    The aim of this study was to determine effect of compressive cyclic loading on fatigue resistance and microleakage of monolithic CAD/CAM molar ceramic and composite crowns. Thirty-two extracted molars were prepared to receive CEREC crowns according to manufacturer's guidelines using a special paralleling device (Parallel-A-Prep). Sixteen feldspathic ceramic crowns (VITABLOCS Mark II) (VMII) and 16 resin-composite crowns (Paradigm-MZ100 blocks) (PMZ) were milled using a CEREC-3D machine. Eight crowns of each group were cemented to their respective teeth using self-etching resin cement (Panavia-F-2.0) (PAN), and eight were cemented using self-adhesive resin cement (RelyX-Unicem-Clicker) (RXU). Following storage for 1 week in water, specimens were subjected to uniaxial compressive cyclic loading in an Instron testing machine at 12 Hz for 1,000,000 cycles. Load was applied at the central fossa, and the cycle range was 60-600 N. Specimens were then subjected to microleakage testing. Data were statistically analyzed using factorial ANOVA and Post Hoc (Tukey HSD) tests. All composite crowns survived compressive cyclic loading without fracture, while three ceramic crowns from the subgroup cemented with RXU developed surface cracks at the center of occlusal surfaces, extending laterally. Microleakage scores of ceramic crowns cemented with PAN were significantly lower than those of the other three subgroups (p < 0.05). After 1,000,000 cycles of compressive cyclic loading, PMZ composite molar crowns were more fatigue-resistant than VMII ceramic crowns. Cement type had a significant effect on fatigue resistance of the ceramic crowns but not the composite ones. Microleakage scores of ceramic crowns cemented with PAN were significantly lower than those of the other subgroups (p < 0.05). © 2011 by The American College of Prosthodontists.

  12. 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…

  13. Chemical resistance, void content and tensile properties of oil palm/jute fibre reinforced polymer hybrid composites

    International Nuclear Information System (INIS)

    Jawaid, M.; Khalil, H.P.S. Abdul; Bakar, A. Abu; Khanam, P. Noorunnisa

    2011-01-01

    Tri layer hybrid composites of oil palm empty fruit bunches (EFB) and jute fibres was prepared by keeping oil palm EFB as skin material and jute as the core material and vice versa. The chemical resistance, void content and tensile properties of oil palm EFB/Jute composites was investigated with reference to the relative weight of oil palm EFB/Jute, i.e. 4:1, the fibre loading was optimized and different layering pattern were investigated. It is found from the chemical resistance test that all the composites are resistant to various chemicals. It was observed that marked reduction in void content of hybrid composites in different layering pattern. From the different layering pattern, the tensile properties were slightly higher for the composite having jute as skin and oil palm EFB as core material. Scanning electron microscopy (SEM) was used to study tensile fracture surfaces of different composites.

  14. Erosion resistance of composite materials on titanium, zirconium and aluminium nitride base under the electron beam effect

    International Nuclear Information System (INIS)

    Verkhoturov, A.D.; Kuzenkova, M.A.; Slutskin, M.G.; Kravchuk, L.A.

    1977-01-01

    Erosion resistance of composites based on nitrides of titanium, zirconium and aluminium to spark and electron beam processing has been studied. The erosion resistance in spark processing is shown to depend on specific electric resistance of the alloys. TiN-AlN and ZrN-AlN alloys containing more than 70% AlN (with specific electric resistance more than 10 6 -10 7 ohm/cm) caot be processed by spark method. It is shown that erosion of the composites by an electron beam depends primarily on the rate of evaporation of the components

  15. Concepts for Reusing Composite Materials from Decommissioned Wind Turbine Blades in Affordable Housing

    Directory of Open Access Journals (Sweden)

    Lawrence C. Bank

    2018-01-01

    Full Text Available The very rapid growth in wind energy technology in the last 15 years has led to a rapid growth in the amount of non-biodegradable, thermosetting fiber reinforced polymer (FRP composite materials used in wind turbine blades. This paper discusses conceptual architectural and structural options for recycling these blades by reusing parts of wind turbine blades in new or retrofitted housing projects. It focuses on large-sized FRP pieces that can be salvaged from the turbine blades and can potentially be useful in infrastructure projects where harsh environmental conditions (water and high humidity exist. Since reuse design should be for specific regional locations and architectural characteristics the designs presented in this paper are for the coastal regions of the Yucatan province in Mexico on the Gulf of Mexico where low-quality masonry block informal housing is vulnerable to severe hurricanes and flooding. To demonstrate the concept a prototype 100 m long wind blade model developed by Sandia National Laboratories is used to show how a wind blade can be broken down into parts, thus making it possible to envision architectural applications for the different wind blade segments for housing applications.

  16. Multilayer oxidation resistant coating for SiC coated carbon/carbon composites at high temperature

    International Nuclear Information System (INIS)

    Li Hejun; Jiao Gengsheng; Li Kezhi; Wang Chuang

    2008-01-01

    To prevent carbon/carbon (C/C) composites from oxidation, a multilayer coating based on molybdenum disilicide and titanium disilicide was formed using a two-step pack cementation technique in argon atmosphere. XRD and SEM analysis showed that the internal coating was a bond SiC layer that acts as a buffer layer, and that the external multilayer coating formed in the two-step pack cementation was composed of two MoSi 2 -TiSi 2 -SiC layers. This coating, which is characterized by excellent thermal shock resistance, could effectively protect the composites from exposure to an oxidizing atmosphere at 1773 K for 79 h. The oxidation of the coated C/C composites was primarily due to the reaction of C/C matrix and oxygen diffusing through the penetrable cracks in the coating

  17. Radiation-resistant composite scintillators based on GSO and GPS grains

    Energy Technology Data Exchange (ETDEWEB)

    Boyarintsev, A.Yu. [Institute for Scintillation Materials, National Academy of Sciences of Ukraine, 60 Nauki Avenue, 61001 Kharkiv (Ukraine); Galunov, N.Z. [Institute for Scintillation Materials, National Academy of Sciences of Ukraine, 60 Nauki Avenue, 61001 Kharkiv (Ukraine); V.N. Karasin Kharkov National University, 4 Svobody Sq., 61022 Kharkiv (Ukraine); Gerasymov, Ia.V.; Karavaeva, N.L. [Institute for Scintillation Materials, National Academy of Sciences of Ukraine, 60 Nauki Avenue, 61001 Kharkiv (Ukraine); Krech, A.V., E-mail: AntonKrech@gmail.com [Institute for Scintillation Materials, National Academy of Sciences of Ukraine, 60 Nauki Avenue, 61001 Kharkiv (Ukraine); Levchuk, L.G.; Popov, V.F. [National Science Center, Kharkov Institute of Physics and Technology, 1 Akademicheskaya Str., 61108 Kharkiv (Ukraine); Sidletskiy, O.Ts. [Institute for Scintillation Materials, National Academy of Sciences of Ukraine, 60 Nauki Avenue, 61001 Kharkiv (Ukraine); Sorokin, P.V. [National Science Center, Kharkov Institute of Physics and Technology, 1 Akademicheskaya Str., 61108 Kharkiv (Ukraine); Tarasenko, O.A. [Institute for Scintillation Materials, National Academy of Sciences of Ukraine, 60 Nauki Avenue, 61001 Kharkiv (Ukraine)

    2017-01-01

    The effect of irradiation on the scintillation light output, optical transmittance, and luminescent spectra of composite scintillators based on grains of single crystals Gd{sub 2}SiO{sub 5}:Ce (GSO) and Gd{sub 2}Si{sub 2}O{sub 7}:Ce (GPS) is studied. The dielectric gel Sylgard-184 is the base and the binder for the grains inside the composite scintillator. The paper presents and analyzes the results obtained for the scintillators exposed by 10 MeV electrons from the linear electron accelerator at room temperature. The exposure doses D≤250 Mrad. The dose rate is 0.2 or 1500 Mrad/h. The study has shown that the composite scintillators based on the grains of GSO and GPS are radiation-resistant over the range of the irradiation.

  18. Aliza Shvarts’s Art of Aborting: Queer Conceptions and Resistance to Reproductive Futurism

    Directory of Open Access Journals (Sweden)

    Ana Grahovac

    2013-07-01

    Full Text Available In April 2008, the Yale Daily News published an article introducing Yale University fine arts student Aliza Shvarts's senior undergraduate art project. In the article, Shvarts announced that as part of her project she had been privately artificially inseminating herself every month during a nine-month period, and performing self-induced miscarriages by ingesting abortifacient drugs each month. The announcement ignited a national controversy, sparking university protests and 'pro-life' outcries across internet communities. Ultimately, the Yale School of Art banned the project from being exhibited. No feminist made an immediate defence of Shvarts's work. Through an in-depth exploration of Shvarts's art project, this essay aims to critically interrogate the politics of reproduction and the rhetoric of futurity in relation to a woman's social and symbolic positioning in a culture that places heterosexual reproduction and the institution of family at the heart of future. I argue that Shvarts's project was an attempt to explore how art could be a means to empty the realm of femininity of its symbolic 'function' within a patriarchal order. By means of her radical refusal of reproduction, manifested in a series of repeated abortions, she staged a resistance to the patriarchal symbolic positioning of a woman – the positioning within which a woman's life is intelligible insofar as it follows the pre-determined reproductive narrative of 'natural' womanhood (birth, marriage, motherhood and death – so that a multitude of new narratives and possibilities could be birthed. I argue that Shvarts is the author of the possibility for imagining the future that is not mapped in advance for a woman – the future in which she is not an 'object' of reproduction but an 'author'. Drawing on Jack J. Halberstam's concept of 'shadow feminism' and Lee Edelman's 'reproductive futurism', I will also suggest that Shvarts's performance provides an invaluable reflection

  19. Wear Resistance Properties Reinforcement Using Nano-Al/Cu Composite Coating in Sliding Bearing Maintenance.

    Science.gov (United States)

    Liu, Hongtao; Li, Zhixiong; Wang, Jianmei; Sheng, Chenxing; Liu, Wanli

    2018-03-01

    Sliding bearing maintenance is crucial for reducing the cost and extending the service life. An efficient and practical solution is to coat a restorative agent onto the worn/damaged bearings. Traditional pure-copper (Cu) coating results in a soft surface and poor abrasion resistance. To address this issue, this paper presents a nano-composite repairing coating method. A series of nano-Al/Cu coatings were prepared on the surface of 45 steel by composite electro-brush plating (EBP). Their micro-hardness was examined by a MHV-2000 Vickers hardness tester, and tribological properties by a UMT-2M Micro-friction tester, 3D profiler and SEM. Then, the influence of processing parameters such as nano-particle concentration and coating thickness on the micro-hardness of nano-Al/Cu coating was analyzed. The experimental analysis results demonstrate that, when the nano-Al particle concentration in electrolyte was 10 g/L, the micro-hardness of the composite coating was 1.1 times as much as that of pure-Cu coating. When the Al nano-particle concentration in electrolyte was 20 g/L, the micro-hardness of the composite coating reached its maximum value (i.e., 231.6 HV). Compared with the pure-Cu coating, the hardness and wear resistance of the nano-composite coating were increased, and the friction coefficient and wear volume were decreased, because of the grain strengthening and dispersion strengthening. The development in this work may provide a feasible and effective nano-composite EBP method for sliding bearing repair.

  20. The correlation of low-velocity impact resistance of graphite-fiber-reinforced composites with matrix properties

    Science.gov (United States)

    Bowles, Kenneth J.

    1988-01-01

    Summarized are basic studies that were conducted to correlate the impact resistance of graphite-fiber-reinforced composites with polymer matrix properties. Three crosslinked epoxy resins and a linear polysulfone were selected as composite matrices. As a group, these resins possess a significantly large range of mechanical properties. The mechanical properties of the resins and their respective composites were measured. Neat resin specimens and unidirectional and crossply composite specimens were impact tested with an instrumented dropweight tester. Impact resistances of the specimens were assesseed on the basis of loading capability, energy absorption, and extent of damage.

  1. Optimal Electrode Selection for Electrical Resistance Tomography in Carbon Fiber Reinforced Polymer Composites

    Science.gov (United States)

    Escalona Galvis, Luis Waldo; Diaz-Montiel, Paulina; Venkataraman, Satchi

    2017-01-01

    Electrical Resistance Tomography (ERT) offers a non-destructive evaluation (NDE) technique that takes advantage of the inherent electrical properties in carbon fiber reinforced polymer (CFRP) composites for internal damage characterization. This paper investigates a method of optimum selection of sensing configurations for delamination detection in thick cross-ply laminates using ERT. Reduction in the number of sensing locations and measurements is necessary to minimize hardware and computational effort. The present work explores the use of an effective independence (EI) measure originally proposed for sensor location optimization in experimental vibration modal analysis. The EI measure is used for selecting the minimum set of resistance measurements among all possible combinations resulting from selecting sensing electrode pairs. Singular Value Decomposition (SVD) is applied to obtain a spectral representation of the resistance measurements in the laminate for subsequent EI based reduction to take place. The electrical potential field in a CFRP laminate is calculated using finite element analysis (FEA) applied on models for two different laminate layouts considering a set of specified delamination sizes and locations with two different sensing arrangements. The effectiveness of the EI measure in eliminating redundant electrode pairs is demonstrated by performing inverse identification of damage using the full set and the reduced set of resistance measurements. This investigation shows that the EI measure is effective for optimally selecting the electrode pairs needed for resistance measurements in ERT based damage detection. PMID:28772485

  2. Static resistance function for steel-plate composite (SC) walls subject to impactive loading

    Energy Technology Data Exchange (ETDEWEB)

    Bruhl, Jakob C., E-mail: jbruhl@purdue.edu; Varma, Amit H., E-mail: ahvarma@purdue.edu; Kim, Joo Min, E-mail: kim1493@purdue.edu

    2015-12-15

    Highlights: • An idealized static resistance function for SC walls is proposed. • The influence of design parameters on static resistance is explained. • SDOF models can accurately estimate global response of SC walls to missile impact. - Abstract: Steel-plate composite (SC) walls consist of a plain concrete core reinforced with two steel faceplates on the surfaces. Modules (consisting of steel faceplates, shear connectors and tie-bars) can be shop-fabricated and shipped to the site for erection and concrete casting, which expedites construction schedule and thus economy. SC structures have recently been used in nuclear power plant designs and are being considered for the next generation of small modular reactors. Design for impactive and impulsive loading is an important consideration for SC walls in safety-related nuclear facilities. The authors have previously developed design methods to prevent local failure (perforation) of SC walls due to missile impact. This paper presents the development of static resistance functions for use in single-degree-of-freedom (SDOF) analyses to predict the maximum displacement response of SC walls subjected to missile impact and designed to resist local failure (perforation). The static resistance function for SC walls is developed using results of numerical analyses and parametric studies conducted using benchmarked 3D finite element (FE) models. The influence of various design parameters are discussed and used to develop idealized bilinear resistance functions for SC walls with fixed edges and simply supported edges. Results from dynamic non-linear FE analysis of SC panels subjected to rigid missile impact are compared with the maximum displacements predicted by SDOF analyses using the bilinear resistance function.

  3. Static resistance function for steel-plate composite (SC) walls subject to impactive loading

    International Nuclear Information System (INIS)

    Bruhl, Jakob C.; Varma, Amit H.; Kim, Joo Min

    2015-01-01

    Highlights: • An idealized static resistance function for SC walls is proposed. • The influence of design parameters on static resistance is explained. • SDOF models can accurately estimate global response of SC walls to missile impact. - Abstract: Steel-plate composite (SC) walls consist of a plain concrete core reinforced with two steel faceplates on the surfaces. Modules (consisting of steel faceplates, shear connectors and tie-bars) can be shop-fabricated and shipped to the site for erection and concrete casting, which expedites construction schedule and thus economy. SC structures have recently been used in nuclear power plant designs and are being considered for the next generation of small modular reactors. Design for impactive and impulsive loading is an important consideration for SC walls in safety-related nuclear facilities. The authors have previously developed design methods to prevent local failure (perforation) of SC walls due to missile impact. This paper presents the development of static resistance functions for use in single-degree-of-freedom (SDOF) analyses to predict the maximum displacement response of SC walls subjected to missile impact and designed to resist local failure (perforation). The static resistance function for SC walls is developed using results of numerical analyses and parametric studies conducted using benchmarked 3D finite element (FE) models. The influence of various design parameters are discussed and used to develop idealized bilinear resistance functions for SC walls with fixed edges and simply supported edges. Results from dynamic non-linear FE analysis of SC panels subjected to rigid missile impact are compared with the maximum displacements predicted by SDOF analyses using the bilinear resistance function.

  4. Fatigue resistance and stiffness of glass fiber-reinforced urethane dimethacrylate composite.

    Science.gov (United States)

    Narva, Katja K; Lassila, Lippo V J; Vallittu, Pekka K

    2004-02-01

    Retentive properties of cast metal clasps decrease over time because of metal fatigue. Novel fiber-reinforced composite materials are purported to have increased fatigue resistance compared with metals and may offer a solution to the problem of metal fatigue. The aim of this study was to investigate the fatigue resistance and stiffness of E-glass fiber-reinforced composite. Twelve cylindrical fiber-reinforced composite test cylinders (2 mm in diameter and 60 mm in length) were made from light-polymerized urethane dimethacrylate monomer with unidirectional, single-stranded, polymer preimpregnated E-glass fiber reinforcement. Six cylinders were stored in dry conditions and 6 in distilled water for 30 days before testing. Fatigue resistance was measured by a constant-deflection fatigue test with 1 mm of deflection across a specimen span of 11 mm for a maximum of 150,000 loading cycles. The resistance of the cylinder against deflection was measured (N) and the mean values of the force were compared by 1-way analysis of variance (alpha = .05). The flexural modulus (GPa) was calculated for the dry and water-stored cylinders for the first loading cycle. Scanning electron microscopy was used to assess the distribution of the fibers, and the volume percent of fibers and polymer were assessed by combustion analysis. The test cylinders did not fracture due to fatigue following 150,000 loading cycles. Flexural modulus at the first loading cycle was 18.9 (+/- 2.9) GPa and 17.5 (+/- 1.7) GPa for the dry and water-stored cylinders, respectively. The mean force required to cause the first 1-mm deflection was 33.5 (+/- 5.2) N and 37.7 (+/- 3.6) N for the dry and water stored cylinders, respectively; however, the differences were not significant. After 150,000 cycles the mean force to cause 1-mm deflection was significantly reduced to 23.4 (+/- 8.5) N and 13.1 (+/- 3.5) N, respectively (P fiber- and polymer-rich areas within the specimens and indicated that individual fibers were

  5. Mechanical Properties and Chemical Resistance of New Composites for Oil Pump Impellers

    Directory of Open Access Journals (Sweden)

    Dilyus I. Chukov

    2018-05-01

    Full Text Available In this paper, a new class of high-performance composites and a method of their production based on the carbonization of an elastomeric matrix are proposed. The use of elastomeric matrix makes it possible to manufacture products with complex shapes, while the subsequent carbonization can significantly improve their properties by changing the chemical nature of the elastomeric matrix. Such an approach can reduce the products’ machining cost, especially for composites reinforced with super hard fillers such as silicon carbide at high filling degrees. Low-temperature carbonization makes it possible to obtain composites with mechanical behavior similar to that of ceramics. In contrast to classical elastomeric materials, the nitrile butadiene rubber (NBR-based compounds were highly filled (300 parts per hundred rubber-PHR with different carbon fillers and silicon carbide; then cured and carbonized at low-temperature 360 °C with the carbonization cycle of 12 h. The feasibility of the production method was validated through the manufacturing of products with complex shapes—impellers for electric centrifugal pumps. It was found that the carbonized composites have good chemical resistance and low water absorption. The composites have high Shore D hardnesses (93–96, ultimate tensile strengths (62–85 MPa, Young’s moduli (17–24 GPa, and compressive strengths (155–181 MPa.

  6. Highly sensitive piezo-resistive graphite nanoplatelet-carbon nanotube hybrids/polydimethylsilicone composites with improved conductive network construction.

    Science.gov (United States)

    Zhao, Hang; Bai, Jinbo

    2015-05-13

    The constructions of internal conductive network are dependent on microstructures of conductive fillers, determining various electrical performances of composites. Here, we present the advanced graphite nanoplatelet-carbon nanotube hybrids/polydimethylsilicone (GCHs/PDMS) composites with high piezo-resistive performance. GCH particles were synthesized by the catalyst chemical vapor deposition approach. The synthesized GCHs can be well dispersed in the matrix through the mechanical blending process. Due to the exfoliated GNP and aligned CNTs coupling structure, the flexible composite shows an ultralow percolation threshold (0.64 vol %) and high piezo-resistive sensitivity (gauge factor ∼ 10(3) and pressure sensitivity ∼ 0.6 kPa(-1)). Slight motions of finger can be detected and distinguished accurately using the composite film as a typical wearable sensor. These results indicate that designing the internal conductive network could be a reasonable strategy to improve the piezo-resistive performance of composites.

  7. EFFECT OF SURFACE SEALING ON STAIN RESISTANCE OF A NANO-HYBRID RESIN COMPOSITE*

    Directory of Open Access Journals (Sweden)

    Günçe SAYGI

    2015-04-01

    Full Text Available Purpose: This study investigated the influence of sealant application on stain resistance of a nanohybrid resin composite compared to the efficacy of a bonding agent used as a surface sealant on prolonging color stability of the resin composite. Materials and Methods: 28 disc-shaped materials were prepared from a nano-hybrid resin composite Filtek Z550 and assigned to four groups: G1K: nonsealed; G2:Adper Single Bond; G3: Fortify ; G4: Biscover LV. After 24 h storage in distilled water at 37˚C, all specimens were subjected to thermocycling and immersed into coffee solution. Color measurements were performed using spectrophotometer (VITA Easyshade; Vident according to CIEL*a*b* system. Results: Color change values were significantly different among the groups in each evaluation period except for after thermocycling (p<0.05. For 7 days evaluation period, the difference between G3 and G4 group was statistically significant while G4 exhibited statistically significant differences (p<0.05 and p<0.0001 respectively compared to control (G1 in 14 day whereas no significant difference was found between GI and GII in 28-day evaluation period. However, ΔE values of sealed specimens (GIII, GIV differed significantly from non-sealed (GI specimens after 28 days of immersion in coffee solution (p<0.05 and p<0.0001 respectively. Conclusion: It may be concluded that using a bonding agent as a surface sealant does not increase stain resistance of resin composites of the sealants evaluated. Biscover LV showed the highest efficacy to prolong color stability of the resin composite.

  8. Evidence-based tick acaricide resistance intervention strategy in Uganda: Concept and feedback of farmers and stakeholders.

    Science.gov (United States)

    Vudriko, Patrick; Okwee-Acai, James; Byaruhanga, Joseph; Tayebwa, Dickson Stuart; Omara, Robert; Muhindo, Jeanne Bukeka; Lagu, Charles; Umemiya-Shirafuji, Rika; Xuan, Xuenan; Suzuki, Hiroshi

    2018-02-01

    The emergence of multi-acaricide resistant ticks has led to unprecedented level of acaricide failure in central and western Uganda. In the absence of a national acaricide resistance management strategy, the country's dairy sector is threatened by upsurge of ticks and tick-borne diseases. In this study, we developed a short-to-medium-term intervention approach called Evidence-Based Acaricide Tick Control (EBATIC): Identify, Test, Intervene and Eradicate (IT-IE). Furthermore, the perception of 199 farmers and extension workers, 12 key informants in four districts and 47 stakeholders in the animal industry in Uganda were assessed using semi-structured questionnaires. We report that the establishment of a specialized laboratory is pivotal in identifying and testing (IT) acaricide resistant ticks for prompt intervention and eradication (IE). The laboratory test results and the farm tick control gaps identified are very important in guiding acaricide resistance management strategies such as evidence-based acaricide rotation, development and dissemination of extension materials, training of farmers and extension workers, and stakeholders' engagement towards finding sustainable solutions. All the 47 stakeholders and 91.0% (181/199) of the farmers and extension workers reported that the EBATIC approach will help in solving the tick acaricide resistance crisis in Uganda. Similarly, all the 12 key informants and 92.5% (184/199) of the farmers and extension workers suggested that the EBATIC approach should be sustained and rolled out to other districts. The EBATIC stakeholders' dialogue generated both short-to-medium and long-term strategies for sustainable management of tick acaricide resistance in the country. Overall, the positive feedback from farmers, district veterinarians and stakeholders in the animal industry suggest that the EBATIC approach is a useful proof-of-concept on scalable intervention pathway against tick acaricide resistance in Uganda with possibility of

  9. Electrical resistivity and thermal properties of compatibilized multi-walled carbon nanotube/polypropylene composites

    Directory of Open Access Journals (Sweden)

    A. Szentes

    2012-06-01

    Full Text Available The electrical resistivity and thermal properties of multi-walled carbon nanotube/polypropylene (MWCNT/PP composites have been investigated in the presence of coupling agents applied for improving the compatibility between the nanotubes and the polymer. A novel olefin-maleic-anhydride copolymer and an olefin-maleic-anhydride copolymer based derivative have been used as compatibilizers to achieve better dispersion of MWCNTs in the polymer matrix. The composites have been produced by extrusion followed by injection moulding. They contained different amounts of MWCNTs (0.5, 2, 3 and 5 wt% and coupling agent to enhance the interactions between the carbon nanotubes and the polymer. The electrical resistivity of the composites has been investigated by impedance spectroscopy, whereas their thermal properties have been determined using a thermal analyzer operating on the basis of the periodic thermal perturbation method. Rheological properties, BET-area and adsorption-desorption isotherms have been determined. Dispersion of MWCNTs in the polymer has been studied by scanning electron microscopy (SEM.

  10. Effect of Fiber Layers on the Fracture Resistance of Fiber Reinforced Composite Bridges

    Directory of Open Access Journals (Sweden)

    A Fazel

    2011-08-01

    Full Text Available Introduction: The purpose of this in vitro study was to introduce the fiber reinforced composite bridges and evaluate the most suitable site and position for placement of fibers in order to get maximum strength. Methods: The study included 20 second premolars and 20 second molars selected for fabricating twenty fiber reinforced composite bridges. Twenty specimens were selected for one fiber layer and the remaining teeth for two fiber layers. In the first group, fibers were placed in the inferior third and in the second group, fibers were placed in both the middle and inferior third region. After tooth preparation, the restorations were fabricated, thermocycled and then loaded with universal testing machine in the middle of the pontics with crosshead speed of 1mm/min. Data was analyzed by Kolmogorov-Smirnov test, Independent sample t test and Kaplan-Meier test. Mode of failure was evaluated using stereomicroscope. Results: Mean fracture resistance for the first and second groups was 1416±467N and 1349±397N, respectively. No significant differences were observed between the groups (P>0.05.In the first group, 5 specimens had delamintation and 5 specimens had detachment between fibers and resin composite. In the second group, there were 4 and 6 delaminations and detachments, respectively. There was no fracture within the fiber. Conclusion: In the fiber reinforced fixed partial dentures, fibers reinforce the tensile side of the connectors but placement of additional fibers at other sites does not increase the fracture resistance of the restoration.

  11. Resistivity tomography-basic concepts and its application. Hiteiko tomography no kiso to oyo

    Energy Technology Data Exchange (ETDEWEB)

    Shima, H

    1990-12-31

    In this paper, principles and characteristics of resistivity tomography are outlined, and its application examples are described. Resistivity tomography is a technology to measure electric potential of many electrodes placed on the earth {prime} s surface or in the well and to analyze the resistivity distribution in the objective area. Arrangement of electrodes (current electrodes and potential electrodes) is determined taking account of the sensitivity distribution. Also, measurements need to be done not only between the surface and a borehole and between boreholes, but also along the wall of a borehole. After the measured data are corrected according to the influence of topography, the initial model is revised repeatedly with the Alpha Center method, and then, resistivity distribution maps are obtained. As an example of field application of resistivity tomography, a geological survey using three boreholes at the scheduled construction site for a dam is described. In this survey, distribution conditions of surface soil, gravel, and andesite were confirmed, and the results almost agreed with the results of seismic tomography. Moreover, another survey with resistivity tomography was carried out at the test site of hot dry rock power generation in Yamagata Prefecture. There, conductive solution was injected from the borehole after hydraulic fracturing, and cracking conditions of rocks were investigated. 28 refs., 21 figs., 1 tab.

  12. Metal Matrix Composite Coatings of Cupronickel Embedded with Nanoplatelets for Improved Corrosion Resistant Properties

    Directory of Open Access Journals (Sweden)

    Casey R. Thurber

    2018-01-01

    Full Text Available The deterioration of metals under the influence of corrosion is a costly problem faced by many industries. Therefore, particle-reinforced composite coatings are being developed in different technological fields with high demands for corrosion resistance. This work studies the effects of nanoplatelet reinforcement on the durability, corrosion resistance, and mechanical properties of copper-nickel coatings. A 90 : 10 Cu-Ni alloy was coelectrodeposited with nanoplatelets of montmorillonite (Mt embedded into the metallic matrix from electrolytic baths containing 0.05, 0.10, and 0.15% Mt. X-ray diffraction of the coatings indicated no disruption of the crystal structure with addition of the nanoplatelets into the alloy. The mechanical properties of the coatings improved with a 17% increase in hardness and an 85% increase in shear adhesion strength with nanoplatelet incorporation. The measured polarization resistance increased from 11.77 kΩ·cm2 for pure Cu-Ni to 33.28 kΩ·cm2 for the Cu-Ni-0.15% Mt coating after soaking in a simulated seawater environment for 30 days. The incorporation of montmorillonite also stabilized the corrosion potential during the immersion study and increased resistance to corrosion.

  13. Chemical composition and antibacterial activity of Lavandula coronopifolia essential oil against antibiotic-resistant bacteria.

    Science.gov (United States)

    Ait Said, L; Zahlane, K; Ghalbane, I; El Messoussi, S; Romane, A; Cavaleiro, C; Salgueiro, L

    2015-01-01

    The aim of this study was to analyse the composition of the essential oil (EO) of Lavandula coronopifolia from Morocco and to evaluate its in vitro antibacterial activity against antibiotic-resistant bacteria isolated from clinical infections. The antimicrobial activity was assessed by a broth micro-well dilution method using multiresistant clinical isolates of 11 pathogenic bacteria: Klebsiella pneumoniae subsp. pneumoniae, Klebsiella ornithinolytica, Escherichia coli, Enterobacter cloacae, Enterobacter aerogenes, Providencia rettgeri, Citrobacter freundii, Hafnia alvei, Salmonella spp., Acinetobacter baumannii and methicillin-resistant Staphylococcus aureus. The main compounds of the oil were carvacrol (48.9%), E-caryophyllene (10.8%) and caryophyllene oxide (7.7%). The oil showed activity against all tested strains with minimal inhibitory concentration (MIC) values ranging between 1% and 4%. For most of the strains, the MIC value was equivalent to the minimal bactericidal concentration value, indicating a clear bactericidal effect of L. coronopifolia EO.

  14. Influence of electropolishing and anodic oxidation on morphology, chemical composition and corrosion resistance of niobium

    Energy Technology Data Exchange (ETDEWEB)

    Sowa, Maciej; Greń, Katarzyna [Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego Street 6, 44-100 Gliwice (Poland); Kukharenko, Andrey I. [Institute of Metal Physics, Russian Academy of Sciences-Ural Division, S. Kovalevskoi Street 18, 620990 Yekaterinburg (Russian Federation); Ural Federal University, Mira Street 19, 620002 Yekaterinburg, Mira str. 19 (Russian Federation); Korotin, Danila M. [Institute of Metal Physics, Russian Academy of Sciences-Ural Division, S. Kovalevskoi Street 18, 620990 Yekaterinburg (Russian Federation); Michalska, Joanna [Faculty of Materials Engineering and Metallurgy, Silesian University of Technology, Krasińskiego Street 8, 40-019 Katowice (Poland); Szyk-Warszyńska, Lilianna; Mosiałek, Michał [Jerzy Haber Institute of Catalysis and Surface Chemistry PAS, Niezapominajek Street 8, 30-239 Kraków (Poland); Żak, Jerzy [Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego Street 6, 44-100 Gliwice (Poland); Pamuła, Elżbieta [AGH University of Science and Technology, Faculty of Materials Science and Ceramics, Mickiewicza Avenue 30, 30-059 Kraków (Poland); Kurmaev, Ernst Z. [Institute of Metal Physics, Russian Academy of Sciences-Ural Division, S. Kovalevskoi Street 18, 620990 Yekaterinburg (Russian Federation); Cholakh, Seif O. [Ural Federal University, Mira Street 19, 620002 Yekaterinburg, Mira str. 19 (Russian Federation); Simka, Wojciech, E-mail: wojciech.simka@polsl.pl [Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego Street 6, 44-100 Gliwice (Poland)

    2014-09-01

    The work presents results of the studies performed on electropolishing of pure niobium in a bath that contained: sulphuric acid, hydrofluoric acid, ethylene glycol and acetanilide. After the electropolishing, the specimens were subjected to anodic passivation in a 1 mol dm{sup −3} phosphoric acid solution at various voltages. The surface morphology, thickness, roughness and chemical composition of the resulting oxide layers were analysed. Thusly prepared niobium samples were additionally investigated in terms of their corrosion resistance in Ringer's solution. The electropolished niobium surface was determined to be smooth and lustrous. The anodisation led to the growth of barrier-like oxide layers, which were enriched in phosphorus species. - Highlights: • Pure niobium was electropolished and subsequently anodised in a H{sub 3}PO{sub 4} solution. • Phosphorus was successfully introduced into the oxide layers after the treatment. • Corrosion resistance of niobium in Ringer's solution was improved after anodising.

  15. Metagenomic profiling of microbial composition and antibiotic resistance determinants in Puget Sound.

    Science.gov (United States)

    Port, Jesse A; Wallace, James C; Griffith, William C; Faustman, Elaine M

    2012-01-01

    Human-health relevant impacts on marine ecosystems are increasing on both spatial and temporal scales. Traditional indicators for environmental health monitoring and microbial risk assessment have relied primarily on single species analyses and have provided only limited spatial and temporal information. More high-throughput, broad-scale approaches to evaluate these impacts are therefore needed to provide a platform for informing public health. This study uses shotgun metagenomics to survey the taxonomic composition and antibiotic resistance determinant content of surface water bacterial communities in the Puget Sound estuary. Metagenomic DNA was collected at six sites in Puget Sound in addition to one wastewater treatment plant (WWTP) that discharges into the Sound and pyrosequenced. A total of ~550 Mbp (1.4 million reads) were obtained, 22 Mbp of which could be assembled into contigs. While the taxonomic and resistance determinant profiles across the open Sound samples were similar, unique signatures were identified when comparing these profiles across the open Sound, a nearshore marina and WWTP effluent. The open Sound was dominated by α-Proteobacteria (in particular Rhodobacterales sp.), γ-Proteobacteria and Bacteroidetes while the marina and effluent had increased abundances of Actinobacteria, β-Proteobacteria and Firmicutes. There was a significant increase in the antibiotic resistance gene signal from the open Sound to marina to WWTP effluent, suggestive of a potential link to human impacts. Mobile genetic elements associated with environmental and pathogenic bacteria were also differentially abundant across the samples. This study is the first comparative metagenomic survey of Puget Sound and provides baseline data for further assessments of community composition and antibiotic resistance determinants in the environment using next generation sequencing technologies. In addition, these genomic signals of potential human impact can be used to guide initial

  16. Metagenomic profiling of microbial composition and antibiotic resistance determinants in Puget Sound.

    Directory of Open Access Journals (Sweden)

    Jesse A Port

    Full Text Available Human-health relevant impacts on marine ecosystems are increasing on both spatial and temporal scales. Traditional indicators for environmental health monitoring and microbial risk assessment have relied primarily on single species analyses and have provided only limited spatial and temporal information. More high-throughput, broad-scale approaches to evaluate these impacts are therefore needed to provide a platform for informing public health. This study uses shotgun metagenomics to survey the taxonomic composition and antibiotic resistance determinant content of surface water bacterial communities in the Puget Sound estuary. Metagenomic DNA was collected at six sites in Puget Sound in addition to one wastewater treatment plant (WWTP that discharges into the Sound and pyrosequenced. A total of ~550 Mbp (1.4 million reads were obtained, 22 Mbp of which could be assembled into contigs. While the taxonomic and resistance determinant profiles across the open Sound samples were similar, unique signatures were identified when comparing these profiles across the open Sound, a nearshore marina and WWTP effluent. The open Sound was dominated by α-Proteobacteria (in particular Rhodobacterales sp., γ-Proteobacteria and Bacteroidetes while the marina and effluent had increased abundances of Actinobacteria, β-Proteobacteria and Firmicutes. There was a significant increase in the antibiotic resistance gene signal from the open Sound to marina to WWTP effluent, suggestive of a potential link to human impacts. Mobile genetic elements associated with environmental and pathogenic bacteria were also differentially abundant across the samples. This study is the first comparative metagenomic survey of Puget Sound and provides baseline data for further assessments of community composition and antibiotic resistance determinants in the environment using next generation sequencing technologies. In addition, these genomic signals of potential human impact can be used

  17. Correlation of chemical compositions of cassava varieties to their resistance to Prostephanus truncatus Horn (Coleoptera: Bostrichidae).

    Science.gov (United States)

    Osipitan, Adebola A; Sangowusi, Victoria T; Lawal, Omoniyi I; Popoola, Kehinde O

    2015-01-01

    The preference of cassava as a major host by Prostephanus truncatus Horn is a major constraint to ample production of cassava, Manihot esculenta Crantz and storage. This study analyzed the nutritional and secondary metabolite compositions in 15 cassava varieties, evaluated levels of damage and reproduction by P. truncatus, and assessed their resistance to attack. One hundred grams of dried cassava chips in 250-ml Kilner jars were infested with 10 adult larger grain borerof 0-10 days old and held for 3 months. The nutritional and secondary metabolites compositions of the dry cassava chips were determined using the method of Association of Analytical Chemists . Chip perforation rates in the cassava varieties ranged from 17.7 to 71.6%. The weight of cassava powder varied by about threefold. The final number of larger grain borer in the cassava varieties varied by about sixfold with 63 in 01/0040 and 379 in 01/1368. Hydrocyanic acid content content varied by over 10-fold and correlated negatively with number of larger grain borer. Flavonoid content varied by ∼10%. Tannins and saponin content of the cassava negatively correlated with number of adult P. truncatus. The cassava varieties 95/0166, 92/0326, 01/0040, 05/0024, and 34 91934 had selection index 0.8 were classified as susceptible. The resistance to high damage in the resistant varieties was conferred by secondary metabolites such as tannins, saponins, alkaloids, and hydrocyanic acid content. The genetic variation in cassava varieties could be explored to breed resistant cassava varieties for use in larger grain borer-endemic areas. © The Author 2015. Published by Oxford University Press on behalf of the Entomological Society of America.

  18. Enhancement of the oxidation resistance of carbon fibres in C/C composites via surface treatments

    Energy Technology Data Exchange (ETDEWEB)

    Labruquere, S.; Pailler, R.; Naslain, R. [Bordeaux Univ., Pessac (France). Lab. des Composites Thermostructuraux; Desbat, B. [Lab. de Spectroscopie Moleculaire et Cristalline, Univ. of Bordeaux, Talence (France)

    1997-12-31

    Carbon-carbon (C/C) composites are commonly used in rockets and braking systems. However, the carbon reacts with oxygen, burning away rapidly at temperatures as low as 450 C. This work deals with the protection of carbon fibres from oxidation between 600 and 1000 C. Two kinds of methods were investigated to protect carbon fibres: (i) surface treatment with aqueous solutions (e.g. of H3PO4) and (ii) chemical vapour deposition (CVD) of SiC coatings. Oxidation resistance of the as treated preforms was studied under dry air atmosphere. (orig.) 2 refs.

  19. REM effect on nonmetallic inclusion composition and heat resistance in an austenitic steel

    International Nuclear Information System (INIS)

    Farafonov, V.K.; Shtejnberg, M.M.; Kikhtin, M.V.; Cheremnykh, V.P.; Vojnov, V.V.

    1979-01-01

    Studies were made to elucidate the effect of rare earths (lanthanum, neodymium, praseodymium, cerium) on the composition of non-metallic inclusions and heat resistance of an austenitic chromium-nickel steel. Common sulfide and oxide inclusions are shown to be substituted by rare earth sulfide and oxide inclusions at RE metal content in the steel up to 0.1%. Further increase of RE metal content results in increasing non-metallic inclusions containing RE metals, phosphorus and non-ferrous impurities. Creep rate changes insignificantly at RE metal content up to 0.1%, and then it sharply grows with the quantity of non-metallic inclusions in the steel

  20. A Numerical Analysis of the Resistance and Stiffness of the Timber and Concrete Composite Beam

    Science.gov (United States)

    Szumigała, Ewa; Szumigała, Maciej; Polus, Łukasz

    2015-03-01

    The article presents the results of a numerical analysis of the load capacity and stiffness of the composite timber and concrete beam. Timber and concrete structures are relatively new, they have not been thoroughly tested and they are rarely used because of technological constraints. One of the obstacles to using them is difficulty with finding a method which would allow successful cooperation between concrete and timber, which has been proposed by the authors of the present article. The modern idea of sustainable construction design requires the use of new more environmentally-friendly solutions. Wood as an ecological material is easily accessible, less energy-consuming, and under certain conditions more corrosion-resistant than steel. The analysis presented in the article showed that cooperation between a wooden beam and a concrete slab on profiled steel sheeting is possible. The analysed composite beam has a greater load capacity and stiffness than the wooden beam.

  1. Radiation resistance of the carbon fiber reinforced composite material with PEEK as the matrix resin

    International Nuclear Information System (INIS)

    Sasuga, Tsuneo; Seguchi, Tadao; Sakai, Hideo; Nakakura, Toshiyuki; Masutani, Masahiro.

    1987-01-01

    In the fast breeder reactor etc. the structural materials are exposed to various environment, i.e., repeated high and low temperature, stress, etc. Irradiation effect (electron radiation) in the mechanical characteristic at low and high temperature has been studied in the PEEK-CF, polyarylether · ether · ketone - carbon fiber composite. Following are the results. (1) Radiation resistance of PEEK-CF is higher than that of PEEK-PES-CF, PEEK - polyethersulfone surface treated CF composite. In PEEK-PES-CF, PES is deteriorated by irradiation so the adhesive power lowers. (2) In the unirradiated PEEK-CF, its mechanical characteristic decreases beyond 140 deg C. With increase of the radiation dose, however, the characteristic rises. (3) Mechanical characteristic of PEEK-CF thus little drops by the heat treatment after the irradiation. (Mori, K.)

  2. Wear resistance analysis of the aluminum 7075 alloy and the nanostructured aluminum 7075 - silver nanoparticles composites

    Directory of Open Access Journals (Sweden)

    Estrada-Ruiz R.H.

    2016-01-01

    Full Text Available Nanostructured composites of the aluminum 7075 alloy and carbon-coated silver nanoparticles were synthetized by the mechanical milling technique using a high-energy mill SPEX 8000M; the powders generated were compacted, sintered and hot-extruded to produce 1 cm-diameter bars. The composites were then subjected to a wear test using a pin-on-disc device to validate the hypothesis that second phase-ductile nanometric particles homogenously distributed throughout the metalmatrix improve the wear resistance of the material. It was found that silver nanoparticles prevent the wear of the material by acting as an obstacle to dislocations movement during the plastic deformation of the contact surface, as well as a solid lubricant when these are separated from the metal-matrix.

  3. A Numerical Analysis of the Resistance and Stiffness of the Timber and Concrete Composite Beam

    Directory of Open Access Journals (Sweden)

    Szumigała Ewa

    2015-03-01

    Full Text Available The article presents the results of a numerical analysis of the load capacity and stiffness of the composite timber and concrete beam. Timber and concrete structures are relatively new, they have not been thoroughly tested and they are rarely used because of technological constraints. One of the obstacles to using them is difficulty with finding a method which would allow successful cooperation between concrete and timber, which has been proposed by the authors of the present article. The modern idea of sustainable construction design requires the use of new more environmentally-friendly solutions. Wood as an ecological material is easily accessible, less energy-consuming, and under certain conditions more corrosion-resistant than steel. The analysis presented in the article showed that cooperation between a wooden beam and a concrete slab on profiled steel sheeting is possible. The analysed composite beam has a greater load capacity and stiffness than the wooden beam.

  4. Body composition using deuterated water, index of insulin resistance and cortisol levels in Costa Rican school in the metropolitan area

    International Nuclear Information System (INIS)

    Valverde Vindas, Allan Ignacio

    2014-01-01

    Body composition in the Costa Rican child population is evaluated and analyzed to determine the relationship with the index of insulin resistance and serum cortisol levels. 113 children in the metropolitan area were studied using deuterium isotope techniques as reference method for overweight and obesity. Morning cortisol levels were determined by immunoassay techniques (ELISA). The insulin resistance index of 113 Costa Rican boys and girls is obtained by the homeostatic method and the relationship between body composition with index of insulin resistance or levels of cortisol [es

  5. Effect of different composite core materials on fracture resistance of endodontically treated teeth restored with FRC posts

    OpenAIRE

    PANITIWAT, Prapaporn; SALIMEE, Prarom

    2017-01-01

    Abstract Objective This study evaluated the fracture resistance of endodontically treated teeth restored with fiber reinforced composite posts, using three resin composite core build-up materials, (Clearfil Photo Core (CPC), MultiCore Flow (MCF), and LuxaCore Z-Dual (LCZ)), and a nanohybrid composite, (Tetric N-Ceram (TNC)). Material and Methods Forty endodontically treated lower first premolars were restored with quartz fiber posts (D.T. Light-Post) cemented with resin cement (Panavia F2...

  6. Hemodynamic comparison of mild and severe preeclampsia: concept of stroke systemic vascular resistance index.

    Science.gov (United States)

    Scardo, J; Kiser, R; Dillon, A; Brost, B; Newman, R

    1996-01-01

    Our purpose was to compare baseline hemodynamic parameters of mild and severe preeclampsia. Patients admitted to the Medical University Labor and Delivery Unit with the diagnosis of preeclampsia who had not received prior antihypertensive or magnesium sulfate therapy were recruited for noninvasive hemodynamic monitoring with thoracic electrical bioimpedance. After stabilization in the lateral recumbent position, hemodynamic monitoring was begun. Baseline hemodynamic parameters, mean arterial pressure (MAP), heart rate (HR), systemic vascular resistance index (SVRI), cardiac index (CI), and stroke index (SI) were recorded. Stroke systemic vascular resistance index (SSVRI), the resistance imposed by vasculature on each beat of the heart, was calculated for each patient by multiplying SVRI by HR. For statistical analysis, unpaired Student's t-tests (two-tailed) were utilized (P preclampsia appears to be a more intensely vasoconstricted state than mild preeclampsia. Although CI is inversely proportional to SVRI, increased HR in severe preeclampsia prevents this expected decrease in cardiac output.

  7. Wear resistance of laser-deposited boride reinforced Ti-Nb-Zr-Ta alloy composites for orthopedic implants

    International Nuclear Information System (INIS)

    Samuel, Sonia; Nag, Soumya; Scharf, Thomas W.; Banerjee, Rajarshi

    2008-01-01

    The inherently poor wear resistance of titanium alloys limits their application as femoral heads in femoral (hip) implants. Reinforcing the soft matrix of titanium alloys (including new generation β-Ti alloys) with hard ceramic precipitates such as borides offers the possibility of substantially enhancing the wear resistance of these composites. The present study discusses the microstructure and wear resistance of laser-deposited boride reinforced composites based on Ti-Nb-Zr-Ta alloys. These composites have been deposited using the LENS TM process from a blend of elemental Ti, Nb, Zr, Ta, and boron powders and consist of complex borides dispersed in a matrix of β-Ti. The wear resistance of these composites has been compared with that of Ti-6Al-4V ELI, the current material of choice for orthopedic femoral implants, against two types of counterfaces, hard Si 3 N 4 and softer SS440C stainless steel. Results suggest a substantial improvement in the wear resistance of the boride reinforced Ti-Nb-Zr-Ta alloys as compared with Ti-6Al-4V ELI against the softer counterface of SS440. The presence of an oxide layer on the surface of these alloys and composites also appears to have a substantial effect in terms of enhanced wear resistance

  8. The inaccuracy of conventional one-dimensional parallel thermal resistance circuit model for two-dimensional composite walls

    International Nuclear Information System (INIS)

    Wong, K.-L.; Hsien, T.-L.; Hsiao, M.-C.; Chen, W.-L.; Lin, K.-C.

    2008-01-01

    This investigation is to show that two-dimensional steady state heat transfer problems of composite walls should not be solved by the conventionally one-dimensional parallel thermal resistance circuits (PTRC) model because the interface temperatures are not unique. Thus PTRC model cannot be used like its conventional recognized analogy, parallel electrical resistance circuits (PERC) model which has the unique node electric voltage. Two typical composite wall examples, solved by CFD software, are used to demonstrate the incorrectness. The numerical results are compared with those obtained by PTRC model, and very large differences are observed between their results. This proves that the application of conventional heat transfer PTRC model to two-dimensional composite walls, introduced in most heat transfer text book, is totally incorrect. An alternative one-dimensional separately series thermal resistance circuit (SSTRC) model is proposed and applied to the two-dimensional composite walls with isothermal boundaries. Results with acceptable accuracy can be obtained by the new model

  9. Incorrectness of conventional one-dimensional parallel thermal resistance circuit model for two-dimensional circular composite pipes

    International Nuclear Information System (INIS)

    Wong, K.-L.; Hsien, T.-L.; Chen, W.-L.; Yu, S.-J.

    2008-01-01

    This study is to prove that two-dimensional steady state heat transfer problems of composite circular pipes cannot be appropriately solved by the conventional one-dimensional parallel thermal resistance circuits (PTRC) model because its interface temperatures are not unique. Thus, the PTRC model is definitely different from its conventional recognized analogy, parallel electrical resistance circuits (PERC) model, which has unique node electric voltages. Two typical composite circular pipe examples are solved by CFD software, and the numerical results are compared with those obtained by the PTRC model. This shows that the PTRC model generates large error. Thus, this conventional model, introduced in most heat transfer text books, cannot be applied to two-dimensional composite circular pipes. On the contrary, an alternative one-dimensional separately series thermal resistance circuit (SSTRC) model is proposed and applied to a two-dimensional composite circular pipe with isothermal boundaries, and acceptable results are returned

  10. A biomechanical evaluation of resistance: fundamental concepts for training and sports performance.

    Science.gov (United States)

    Frost, David M; Cronin, John; Newton, Robert U

    2010-04-01

    Newton's second law of motion describes the acceleration of an object as being directly proportional to the magnitude of the net force, in the same direction as the net force and inversely proportional to its mass (a = F/m). With respect to linear motion, mass is also a numerical representation of an object's inertia, or its resistance to change in its state of motion and directly proportional to the magnitude of an object's momentum at any given velocity. To change an object's momentum, thereby increasing or decreasing its velocity, a proportional impulse must be generated. All motion is governed by these relationships, independent of the exercise being performed or the movement type being used; however, the degree to which this governance affects the associated kinematics, kinetics and muscle activity is dependent on the resistance type. Researchers have suggested that to facilitate the greatest improvements to athletic performance, the resistance-training programme employed by an athlete must be adapted to meet the specific demands of their sport. Therefore, it is conceivable that one mechanical stimulus, or resistance type, may not be appropriate for all applications. Although an excellent means of increasing maximal strength and the rate of force development, free-weight or mass-based training may not be the most conducive means to elicit velocity-specific adaptations. Attempts have been made to combat the inherent flaws of free weights, via accommodating and variable resistance-training devices; however, such approaches are not without problems that are specific to their mechanics. More recently, pneumatic-resistance devices (variable) have been introduced as a mechanical stimulus whereby the body mass of the athlete represents the only inertia that must be overcome to initiate movement, thus potentially affording the opportunity to develop velocity-specific power. However, there is no empirical evidence to support such a contention. Future research should

  11. TiO2-TiO2 composite resistive humidity sensor: ethanol crosssensitivity

    International Nuclear Information System (INIS)

    Ghalamboran, Milad; Saedi, Yasin

    2016-01-01

    The fabrication method and characterization results of a TiO 2 -TiO 2 composite bead used for humidity sensing along with its negative cross-sensitivity to ethanol vapor are reported. The bead shaped resistive sample sensors are fabricated by the drop-casting of a TiO 2 slurry on two Pt wire segments. The dried bead is pre-fired at 750°C and subsequently impregnated with a Ti-based sol. The sample is ready for characterization after a thermal annealing at 600°C in air. Structurally, the bead is a composite of the micron-sized TiO 2 crystallites embedded in a matrix of nanometric TiO 2 particle aggregates. The performance of the beads as resistive humidity sensors is recorded at room temperature in standard humidity level chambers. Results evince the wide dynamic range of the sensors fabricated in the low relative humidity range. While the sensor conductance is not sensitive to ethanol vapor in dry air, in humid air, sensor's responses are negatively affected by the contaminant. (paper)

  12. Muscle function and body composition profile in adolescents with restrictive anorexia nervosa: does resistance training help?

    Science.gov (United States)

    Fernández-del-Valle, Maria; Larumbe-Zabala, Eneko; Morande-Lavin, Gonzalo; Perez Ruiz, Margarita

    2016-01-01

    The aim of this study was to analyze the effects of short-term resistance training on the body composition profile and muscle function in a group of Anorexia Nervosa restricting type (AN-R) patients. The sample consisted of AN-R female adolescents (12.8 ± 0.6 years) allocated into the control and intervention groups (n = 18 each). Body composition and relative strength were assessed at baseline, after 8 weeks and 4 weeks following the intervention. Body mass index (BMI) increased throughout the study (p = 0.011). Significant skeletal muscle mass (SMM) gains were found in the intervention group (p = 0.045, d = 0.6) that correlated to the change in BMI (r = 0.51, p  0.60) with change in BMI in both the groups. Significant relative strength increases (p Anorexia Nervosa Restricting Type (AN-R) AN-R is a psychiatric disorder that has a major impact on muscle mass content and function. However, little or no attention has been paid to muscle recovery. High intensity resistance training is safe for AN-R after hospitalization and enhances the force generating capacity as well as muscle mass gains. Skeletal muscle mass content and muscular function improvements are partially maintained for a short period of time when the exercise program ceases.

  13. N-stearoylethanolamine restores pancreas lipid composition in obesity-induced insulin resistant rats.

    Science.gov (United States)

    Onopchenko, Oleksandra V; Kosiakova, Galina V; Oz, Murat; Klimashevsky, Vitaliy M; Gula, Nadiya M

    2015-01-01

    This study investigates the protective effect of N-stearoylethanolamine (NSE), a bioactive N-acylethanolamine , on the lipid profile distribution in the pancreas of obesity-induced insulin resistant (IR) rats fed with prolonged high fat diet (58% of fat for 6 months). The phospholipid composition was determined using 2D thin-layer chromatography. The level of individual phospholipids was estimated by measuring inorganic phosphorus content. The fatty acid (FA) composition and cholesterol level were investigated by gas-liquid chromatography. Compared to controls, plasma levels of triglycerides and insulin were significantly increased in IR rats. The pancreas lipid composition indicated a significant reduction of the free cholesterol level and some phospholipids such as phosphatidylcholine (PtdCho), phosphatidylethanolamine (PtdEtn), phosphatidylinositol (PtdIns), phosphatidylserine (PtdSer) compared to controls. Moreover, the FA composition of pancreas showed a significant redistribution of the main FA (18:1n-9, 18:2n-6, 18:3n-6 and 20:4n-6) levels between phospholipid, free FA, triglyceride fractions under IR conditions that was accompanied by a change in the estimated activities of Δ9-, Δ6-, Δ5-desaturase. Administration of N-stearoylethanolamine (NSE, 50 mg/kg daily per os for 2 weeks) IR rats triggered an increase in the content of free cholesterol, PtdCho and normalization of PtdEtn, PtdSer level. Furthermore, the NSE modulated the activity of desaturases, thus influenced FA composition and restored the FA ratios in the lipid fractions. These NSE-induced changes were associated with a normalization of plasma triglyceride content, considerable decrease of insulin and index HOMA-IR level in rats under IR conditions.

  14. Effect of combined aerobic and resistance training in body composition of obese postmenopausal women

    Directory of Open Access Journals (Sweden)

    Fabrício E. Rossi

    2015-03-01

    Full Text Available The aim of this study was to investigate the effects of a 16-week program of combined aerobic and resistance training on the body composition of postmenopausal women who are obese. The participants were divided into two groups: training group (TG, n = 37 and non-trained control group (CG, n = 18. The trunk fat, fat mass, percentage of fat mass and fat-free mass were estimated using DXA. Three nonconsecutive 24-hour dietary recalls were conducted. The training protocol consisted of 50 minutes of resistance training followed by 30 minutes of aerobic training. After the 16-week training program, differences were observed in trunk fat (CG= 0.064 x TG= -0.571 Kg; p-value = .020, fat mass (CG= -0.088 x TG= -1.037 Kg; p-value = .020 and fat-free mass (CG= -0.388 x TG= 1.049 Kg; p = .001. Therefore, a 16-week program of systematic combined aerobic and resistance training in obese postmenopausal women was effective in improving fat-free mass and decreasing both whole and abdominal adiposity.

  15. Hazardous industrial gases identified using a novel polymer/MWNT composite resistance sensor array

    International Nuclear Information System (INIS)

    Yuana, C.L.; Chang, C.P.; Song, Y.

    2011-01-01

    Highlights: → In this work, a silicon wafer microelectrode substrate for a resistance sensor was fabricated using the semiconductor manufacturing process. → This work developed polymer-functionalized MWNT sensor plat forms for the detection of vapors from chemical agents at different temperatures. → Applied PCA to determine the performance of as-fabricated films for exposure to three chemical agents. - Abstract: Hazardous industrial chemical gases pose a significant threat to the environment and human life. Therefore, there is an urgent need to develop a reliable sensor for identifying these hazardous gases. In this work, a silicon wafer microelectrode substrate for a resistance sensor was fabricated using the semiconductor manufacturing process. Conductive carbon nanotubes were then mixed with six different polymers with different chemical adsorption properties to produce a composite thin film for the fabrication of a chemical sensor array. This array was then utilized to identify three hazardous gases at different temperatures. Experimental results for six polymers for chemical gases, such as tetrahydrofuran (THF), chloroform (CHCl 3 ) and methanol (MeOH) at different temperatures, indicate that the variation in sensitivity resistance increased when the sensing temperature increased. The poly(ethylene adipate)/MWNT sensing film had high sensitivity, excellent selectivity, and good reproducibility in detecting all chemical agent vapors. Additionally, this study utilized a bar chart and statistical methods in principal component analysis to identify gases with the polymer/MWNT sensor.

  16. CMOS sensors in 90 nm fabricated on high resistivity wafers: Design concept and irradiation results

    International Nuclear Information System (INIS)

    Rivetti, A.; Battaglia, M.; Bisello, D.; Caselle, M.; Chalmet, P.; Costa, M.; Demaria, N.; Giubilato, P.; Ikemoto, Y.; Kloukinas, K.; Mansuy, C.; Marchioro, A.; Mugnier, H.; Pantano, D.; Potenza, A.; Rousset, J.; Silvestrin, L.; Wyss, J.

    2013-01-01

    The LePix project aims at improving the radiation hardness and the readout speed of monolithic CMOS sensors through the use of standard CMOS technologies fabricated on high resistivity substrates. In this context, high resistivity means beyond 400Ωcm, which is at least one order of magnitude greater than the typical value (1–10Ωcm) adopted for integrated circuit production. The possibility of employing these lightly doped substrates was offered by one foundry for an otherwise standard 90 nm CMOS process. In the paper, the case for such a development is first discussed. The sensor design is then described, along with the key challenges encountered in fabricating the detecting element in a very deep submicron process. Finally, irradiation results obtained on test matrices are reported

  17. Effect of Different Liners on Fracture Resistance of Premolars Restored with Conventional and Short Fiber-Reinforced Composite Resins.

    Science.gov (United States)

    Shafiei, Fereshteh; Doozandeh, Maryam; Ghaffaripour, Dordaneh

    2018-01-11

    To see whether applying four different liners under short fiber-reinforced composite (SFRC), everX Posterior, compared to conventional composite resin, Z250, affected their strengthening property in premolar MOD cavities. Mesio-occluso-distal (MOD) cavities were prepared in 120 sound maxillary premolars divided into 10 groups (n = 12) in terms of two composite resin types and 4 liners or no liner. For each composite resin, in 5 groups no liner, resin-modified glass ionomer (RMGI), conventional flowable composite (COFL), self-adhesive flowable composite resin (SAFL), and self-adhesive resin cement (SARC) were applied prior to restoring incrementally. After water storage and thermocycling, static fracture resistance was tested. Data (in Newtons) were analyzed using two-way ANOVA (α = 0.05). Fracture resistance was significantly affected by composite resin type (p = 0.02), but not by the liner (p > 0.05). The interaction of the two factors was not statistically significant (p > 0.05). SFRC exhibited higher fracture strength (1470 ± 200 N) compared to conventional composite resin (1350 ± 290), irrespective of the application of liners. Application of SARC and SAFL liners led to a higher number of restorable fractures for both composite resins. The four liners can be used without interfering with the higher efficacy of SFRC, compared to conventional composite resins, to improve the fracture strength of premolar MOD cavities. © 2018 by the American College of Prosthodontists.

  18. A new concept for stainless steels ranking upon the resistance to cavitation erosion

    Science.gov (United States)

    Bordeasu, I.; Popoviciu, M. O.; Salcianu, L. C.; Ghera, C.; Micu, L. M.; Badarau, R.; Iosif, A.; Pirvulescu, L. D.; Podoleanu, C. E.

    2017-01-01

    In present, the ranking of materials as their resistance to cavitation erosion is obtained by using laboratory tests finalized with the characteristic curves mean depth erosion against time MDE(t) and mean depth erosion rate against time MDER(t). In some previous papers, Bordeasu and co-workers give procedures to establish exponential equation representing the curves, with minimum scatter of the experimental obtained results. For a given material, both exponential equations MDE(t) and MDER(t) have the same values for the parameters of scale and for the shape one. For the ranking of materials is sometimes important to establish single figure. Till now in Timisoara Polytechnic University Cavitation Laboratory were used three such numbers: the stable value of the curve MDER(t), the resistance to cavitation erosion (Rcav ≡ 1/MDERstable) and the normalized cavitation resistance Rns which is the rate between vs = MDERstable for the analyzed material and vse= MDERse the mean depth erosion rate for the steel OH12NDL (Rns = vs/vse ). OH12NDL is a material used for manufacturing the blades of numerous Kaplan turbines in Romania for which both cavitation erosion laboratory tests and field measurements of cavitation erosions are available. In the present paper we recommend a new method for ranking the materials upon cavitation erosion resistance. This method uses the scale and shape parameters of the exponential equations which represents the characteristic cavitation erosion curves. Till now the method was applied only for stainless steels. The experimental results show that the scale parameter represents an excellent method for ranking the stainless steels. In the future this kind of ranking will be tested also for other materials especially for bronzes used for manufacturing ship propellers.

  19. Defining the frontiers between antifungal resistance, tolerance and the concept of persistence.

    Science.gov (United States)

    Delarze, Eric; Sanglard, Dominique

    2015-11-01

    A restricted number of antifungal agents are available for the therapy of fungal diseases. With the introduction of epidemiological cut-off values for each agent in important fungal pathogens based on the distribution of minimal inhibitory concentration (MIC), the distinction between wild type and drug-resistant populations has been facilitated. Antifungal resistance has been described for all currently available antifungal agents in several pathogens and most of the associated resistance mechanisms have been deciphered at the molecular level. Clinical breakpoints for some agents have been proposed and can have predictive value for the success or failure of therapy. Tolerance to antifungals has been a much more ignored area. By definition, tolerance operates at antifungal concentrations above individual intrinsic inhibitory values. Important is that tolerance to antifungal agents favours the emergence of persister cells, which are able to survive antifungal therapy and can cause relapses. Here we will review the current knowledge on antifungal tolerance, its potential mechanisms and also evaluate the role of antifungal tolerance in the efficacy of drug treatments. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Fire-Resistant Hydrogel-Fabric Laminates: A Simple Concept That May Save Lives.

    Science.gov (United States)

    Illeperuma, Widusha R K; Rothemund, Philipp; Suo, Zhigang; Vlassak, Joost J

    2016-01-27

    There is a large demand for fabrics that can survive high-temperature fires for an extended period of time, and protect the skin from burn injuries. Even though fire-resistant polymer fabrics are commercially available, many of these fabrics are expensive, decompose rapidly, and/or become very hot when exposed to high temperatures. We have developed a new class of fire-retarding materials by laminating a hydrogel and a fabric. The hydrogel contains around 90% water, which has a large heat capacity and enthalpy of vaporization. When the laminate is exposed to fire, a large amount of energy is absorbed as water heats up and evaporates. The temperature of the hydrogel cannot exceed 100 °C until it is fully dehydrated. The fabric has a low thermal conductivity and maintains the temperature gradient between the hydrogel and the skin. The laminates are fabricated using a recently developed tough hydrogel to ensure integrity of the laminate during processing and use. A thermal model predicts the performance of the laminates and shows that they have excellent heat resistance in good agreement with experiments, making them viable candidates in life saving applications such as fire-resistant blankets or apparel.

  1. Advanced core concepts with enhanced proliferation resistance by transmutation of minor actinides

    International Nuclear Information System (INIS)

    Saito, Masaki

    2005-01-01

    ''Protected Plutonium Production (P 3 )'' has been proposed to establish high burn-up cores and to produce protected with high proliferation resistance due to high decay heat and large number of spontaneous fission neutron of 238 Pu by the transmutation of Minor Actinides (MAs) which is presently treated as high-level waste. The burn-up calculations have shown that the advanced fuel with UO 2 (11-13% enrichment of 235 U) by doping 237 Np to produce 238 Pu in the commercialized large LWRs burn up to 100 GWd/t with 238 Pu to Pu ratio of about 20% which means the fuel is highly protected from proliferation. It was also predicted that medium or small size LWR cores with 15-17% enrichment, liquid metal cooled cores, and gas cooled cores added by 1-2% Np could achieve 100 GWd/t burning with bearing high proliferation resistance. The 237 Np mass balance calculations have revealed that more than 20 nuclear P 3 plants of 300 MWe could be supplied with enough 237 Np from the Japanese commercial plants in equilibrium fuel cycles. From the present studies, it is confirmed that MAs are treated as burnable and fertile materials not only to extend the core life but also to improve plutonium proliferation resistance of the future nuclear energy systems instead of their geological disposal or just their burning through fission. (author)

  2. High corrosion resistance of electroless composite plating coatings on AZ91D magnesium alloys

    International Nuclear Information System (INIS)

    Song, Y.W.; Shan, D.Y.; Han, E.H.

    2008-01-01

    The process of electroless plating Ni-P on AZ91D magnesium alloys was improved. The Ni-P-ZrO 2 composite coatings and multilayer coatings were investigated based on the new electroless plating process. The coatings surface and cross-section morphologies were observed with scanning electron microscopy (SEM). The chemical compositions were analyzed by EDXS. The corrosion behaviors were evaluated by immersion, salt spray and electrochemical tests. The experimental results indicated that the Ni-P-ZrO 2 composite coatings suffered attack in NaCl solution but displayed passivation characteristics in NaOH and Na 2 SO 4 solutions. The corrosion resistance of Ni-P-ZrO 2 coatings was superior to Ni-P coatings due to the effect of ZrO 2 nano-particle. The multilayer coatings consisting of Ni-P-ZrO 2 /electroplating nickel/Ni-P (from substrate to surface) can protect magnesium alloys from corroding more than 1000 h for the salt spray test

  3. The Formation Mechanism and Corrosion Resistance of a Composite Phosphate Conversion Film on AM60 Alloy

    Science.gov (United States)

    Lan, Xiangna; Wang, Chao; Zhang, Qinyong

    2018-01-01

    Magnesium alloy AM60 has high duc and toughness, which is expected to increase in demand for automotive applications. However, it is too active, and coatings have been extensively studied to prevent corrosion. In this work, a Ba-containing composite phosphate film has been prepared on the surface of AM60. The composition and formation mechanism of the film have been investigated using a scanning electronic microscope equipped with energy dispersive X-ray spectroscopy, Fourier transform infrared, X-ray photoelectron spectroscopy, and X-ray diffractometry tests. The corrosion resistance of the film has been measured by electrochemical and immersion tests. The results show that the deposition film has fully covered the substrate but there are some micro-cracks. The structure of the film is complex, and consists of MgHPO4·3H2O, MnHPO4·2.25H2O, BaHPO4·3H2O, BaMg2(PO4)2, Mg3(PO4)2·22H2O, Ca3(PO4)2·xH2O, and some amorphous phases. The composite phosphate film has better anticorrosion performance than the AM60 and can protect the bare alloy from corrosion for more than 12 h in 0.6 M NaCl. PMID:29518038

  4. Effect of the fatty acid composition of acclimated oenological Lactobacillus plantarum on the resistance to ethanol.

    Science.gov (United States)

    Bravo-Ferrada, B M; Gómez-Zavaglia, A; Semorile, L; Tymczyszyn, E E

    2015-02-01

    The aim of this work was to evaluate the changes due to acclimation to ethanol on the fatty acid composition of three oenological Lactobacillus plantarum strains and their effect on the resistance to ethanol and malic acid consumption (MAC). Lactobacillus plantarum UNQLp 133, UNQLp 65.3 and UNQLp 155 were acclimated in the presence of 6 or 10% v/v ethanol, for 48 h at 28°C. Lipids were extracted to obtain fatty acid methyl esters and analysed by gas chromatography interfaced with mass spectroscopy. The influence of change in fatty acid composition on the viability and MAC in synthetic wine was analysed by determining the Pearson correlation coefficient. Acclimated strains showed a significant change in the fatty composition with regard to the nonacclimated strains. Adaptation to ethanol led to a decrease in the unsaturated/saturated ratio, mainly resulting from an increase in the contribution of short-length fatty acid C12:0 and a decrease of C18:1. The content of C12:0 was related to a higher viability after inoculation of synthetic wine. The MAC increased at higher contents in saturated fatty acid, but its efficiency was strain dependent. © 2014 The Society for Applied Microbiology.

  5. The Formation Mechanism and Corrosion Resistance of a Composite Phosphate Conversion Film on AM60 Alloy.

    Science.gov (United States)

    Chen, Jun; Lan, Xiangna; Wang, Chao; Zhang, Qinyong

    2018-03-08

    Magnesium alloy AM60 has high duc and toughness, which is expected to increase in demand for automotive applications. However, it is too active, and coatings have been extensively studied to prevent corrosion. In this work, a Ba-containing composite phosphate film has been prepared on the surface of AM60. The composition and formation mechanism of the film have been investigated using a scanning electronic microscope equipped with energy dispersive X-ray spectroscopy, Fourier transform infrared, X-ray photoelectron spectroscopy, and X-ray diffractometry tests. The corrosion resistance of the film has been measured by electrochemical and immersion tests. The results show that the deposition film has fully covered the substrate but there are some micro-cracks. The structure of the film is complex, and consists of MgHPO₄·3H₂O, MnHPO₄·2.25H₂O, BaHPO₄·3H₂O, BaMg₂(PO₄)₂, Mg₃(PO₄)₂·22H₂O, Ca₃(PO₄)₂·xH₂O, and some amorphous phases. The composite phosphate film has better anticorrosion performance than the AM60 and can protect the bare alloy from corrosion for more than 12 h in 0.6 M NaCl.

  6. Incremental dynamic analysis of concrete moment resisting frames reinforced with shape memory composite bars

    International Nuclear Information System (INIS)

    Zafar, Adeel; Andrawes, Bassem

    2012-01-01

    Fiber reinforced polymer (FRP) reinforcing bars have been used in concrete structures as an alternative to conventional steel reinforcement, in order to overcome corrosion problems. However, due to the linear behavior of the commonly used reinforcing fibers, they are not considered in structures which require ductility and damping characteristics. The use of superelastic shape memory alloy (SMA) fibers with their nonlinear elastic behavior as reinforcement in the composite could potentially provide a solution for this problem. Small diameter SMA wires are coupled with polymer matrix to produce SMA–FRP composite, which is sought in this research as reinforcing bars. SMA–FRP bars are sought in this study to enhance the seismic performance of reinforced concrete (RC) moment resisting frames (MRFs) in terms of reducing their residual inter-story drifts while still maintaining the elastic characteristics associated with conventional FRP. Three story one bay and six story two bay RC MRF prototype structures are designed with steel, SMA–FRP and glass–FRP reinforcement. The incremental dynamic analysis technique is used to investigate the behaviors of the two frames with the three different reinforcement types under a suite of ground motion records. It is found that the frames with SMA–FRP composite reinforcement exhibit higher performance levels including lower residual inter-story drifts, high energy dissipation and thus lower damage, which are important for structures in highly seismic zones. (paper)

  7. Corrosion resistance of Ni-Cr-Mo alloys. Chemical composition and metallurgical condition's effects

    International Nuclear Information System (INIS)

    Zadorozne, N.S.; Rebak, Raul B.

    2009-01-01

    P, may form if Ni-Cr-Mo alloys are exposed for tens of hours in the range of 600 C degrees to 1100 C degrees. These phases could have a detrimental effect upon corrosion resistance and cause a loss of mechanical ductility. The precipitation of TCP phases starts at grain boundaries and for long aging times it progresses to twins boundaries and then the grain bodies. TCP phases are rich in Mo and Cr. Zones in the matrix adjacent to the TCP precipitates may be depleted of Cr and Mo, and the alloy becomes sensitized.The aim of the present work was to compare the general corrosion rate and the crevice corrosion susceptibility of alloys C-22, C-22HS and HYBRID-BC1 in different metallurgical conditions when exposed to hot chloride solutions. The effects of the alloy composition and different heat treatments were assessed. (author)

  8. Renewable and superior thermal-resistant cellulose-based composite nonwoven as lithium-ion battery separator.

    Science.gov (United States)

    Zhang, Jianjun; Liu, Zhihong; Kong, Qingshan; Zhang, Chuanjian; Pang, Shuping; Yue, Liping; Wang, Xuejiang; Yao, Jianhua; Cui, Guanglei

    2013-01-01

    A renewable and superior thermal-resistant cellulose-based composite nonwoven was explored as lithium-ion battery separator via an electrospinning technique followed by a dip-coating process. It was demonstrated that such nanofibrous composite nonwoven possessed good electrolyte wettability, excellent heat tolerance, and high ionic conductivity. The cells using the composite separator displayed better rate capability and enhanced capacity retention, when compared to those of commercialized polypropylene separator under the same conditions. These fascinating characteristics would endow this renewable composite nonwoven a promising separator for high-power lithium-ion battery.

  9. Using Expectancy Value Theory as a Framework to Reduce Student Resistance to Active Learning: A Proof of Concept.

    Science.gov (United States)

    Cooper, Katelyn M; Ashley, Michael; Brownell, Sara E

    2017-01-01

    There has been a national movement to transition college science courses from passive lectures to active learning environments. Active learning has been shown to be a more effective way for students to learn, yet there is concern that some students are resistant to active learning approaches. Although there is much discussion about student resistance to active learning, few studies have explored this topic. Furthermore, a limited number of studies have applied theoretical frameworks to student engagement in active learning. We propose using a theoretical lens of expectancy value theory to understand student resistance to active learning. In this study, we examined student perceptions of active learning after participating in 40 hours of active learning. We used the principal components of expectancy value theory to probe student experience in active learning: student perceived self-efficacy in active learning, value of active learning, and potential cost of participating in active learning. We found that students showed positive changes in the components of expectancy value theory and reported high levels of engagement in active learning, which provide proof of concept that expectancy value theory can be used to boost student perceptions of active learning and their engagement in active learning classrooms. From these findings, we have built a theoretical framework of expectancy value theory applied to active learning.

  10. Fracture Resistance of Endodontically Treated Teeth Restored with 2 Different Fiber-reinforced Composite and 2 Conventional Composite Resin Core Buildup Materials: An In Vitro Study.

    Science.gov (United States)

    Eapen, Ashly Mary; Amirtharaj, L Vijay; Sanjeev, Kavitha; Mahalaxmi, Sekar

    2017-09-01

    The purpose of this in vitro study was to comparatively evaluate the fracture resistance of endodontically treated teeth restored with 2 fiber-reinforced composite resins and 2 conventional composite resin core buildup materials. Sixty noncarious unrestored human maxillary premolars were collected, endodontically treated (except group 1, negative control), and randomly divided into 5 groups (n = 10). Group 2 was the positive control. The remaining 40 prepared teeth were restored with various direct core buildup materials as follows: group 3 teeth were restored with dual-cure composite resin, group 4 with posterior composite resin, group 5 with fiber-reinforced composite resin, and group 6 with short fiber-reinforced composite resin. Fracture strength testing was performed using a universal testing machine. The results were statistically analyzed by 1-way analysis of variance and the post hoc Tukey test. Fracture patterns for each sample were also examined under a light microscope to determine the level of fractures. The mean fracture resistance values (in newtons) were obtained as group 1 > group 6 > group 4 > group 3 > group 5 > group 2. Group 6 showed the highest mean fracture resistance value, which was significantly higher than the other experimental groups, and all the fractures occurred at the level of enamel. Within the limitations of this study, a short fiber-reinforced composite can be used as a direct core buildup material that can effectively resist heavy occlusal forces against fracture and may reinforce the remaining tooth structure in endodontically treated teeth. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  11. Design Concepts for Cooled Ceramic Matrix Composite Turbine Vanes, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The work proposed herein is to demonstrate that the higher temperature capabilities of Ceramic Matrix Composites (CMC) can be fully utilized to reduce emissions and...

  12. Electro-location, tomography and porosity measurements in geotechnical centrifuge models based on electrical resistivity concepts

    Science.gov (United States)

    Li, Zhihua

    This research was focused on the development of electrical techniques for soil characterization and soil dynamic behavior assessment. The research carried out mainly includes (1) development of a needle probe tool for assessment of soil spatial variability in terms of porosity with high-resolution in the centrifuge testing; (2) development of an electro-location technique to accurately detect buried objects' movements inside the soil during dynamic events; (3) collaborative development of a new electrode switching system to implement electrical resistivity tomography, and electro-location with high speed and high resolution. To assess soil spatial variability with high-resolution, electrical needle probes with different tip shapes were developed to measure soil electrical resistivity. After normalizing soil resistivity by pore fluid resistivity, this information can be correlated to soil porosity. Calibrations in laboratory prepared soils were conducted. Loosening due to insertion of needle probes was evaluated. A special needle probe tool, along with data acquisition and data processing tools were developed to be operated by the new NEES robot on the centrifuge. The needle probes have great potential to resolve interfaces between soil layers and small local porosity variations with a spatial resolution approximately equal to the spacing between electrodes (about half of the probe diameter). A new electrode switching system was developed to accurately detect buried objects' movements using a new electro-location scheme. The idea was to establish an electromagnetic field in a centrifuge model by injecting low-frequency alternating currents through pairs of boundary electrodes. The locations of buried objects are related to the potentials measured on them. A closed form expression for the electric field in a rectangular specimen with insulated boundaries was obtained based on the method of images. Effects of sampling parameters on spatial resolution and tradeoffs

  13. Resistivity and Its Anisotropy Characterization of 3D-Printed Acrylonitrile Butadiene Styrene Copolymer (ABS/Carbon Black (CB Composites

    Directory of Open Access Journals (Sweden)

    Jie Zhang

    2017-01-01

    Full Text Available The rapid printing of 3D parts with desired electrical properties enables numerous applications. Fused deposition modeling (FDM using conductive thermoplastic composites has been a valuable approach for such fabrication. The parts produced by FDM possess various controllable structural features, but the effects of the structural features on the electrical properties remain to be determined. This study investigated the effects of these features on the electrical resistivity and resistivity anisotropy of 3D-printed ABS/CB composites. The effects of the process parameters of FDM, including the layer thickness, raster width, and air gap, on the resistivity in both the vertical and horizontal directions for cubic samples were studied because the internal structure of the printed parts depended on those process parameters. The resistivities of printed parts in different parameter combinations were measured by an impedance analyzer and finite element models were created to investigate the relationship between the resistivity and the internal structure. The results indicated that the parameters remarkably affected the resistivity due to the influence of voids and the bonding condition between adjacent fibers. The resistivity in the vertical direction ranged from 70.40 ± 2.88 Ω·m to 180.33 ± 8.21 Ω·m, and the resistivity in the horizontal direction ranged from 41.91 ± 2.29 Ω·m to 58.35 ± 0.61 Ω·m at the frequency of 1 kHz. Moreover, by adjusting the resistivities in different directions, the resistivity anisotropy of the printed parts can be manipulated from 1.01 to 3.59. This research may serve as a reference to fabricate parts with sophisticated geometry with desired electrical resistivity and resistivity anisotropy.

  14. THE INFLUENCE OF THE FILLER GRAIN COMPOSITION ON THE PROPERTIES OF THE HEAT-RESISTANT BASALTIC CONCRETE

    Directory of Open Access Journals (Sweden)

    A. M. Gadzhiev

    2017-01-01

    Full Text Available Objectives. The optimal granulometric composition of filler compound ensures the production of concrete having improved  physical and mechanical characteristics, as well as minimal binder  consumption. The properties of heat-resistant concrete largely  depend on the type and the ratio of its components. Taking this into  account, the aim of the study is to determine the optimal grain composition of heat-resistant concrete.Methods. Methods for optimising the properties of heatresistant basaltic concrete with a composite binder and  mechanochemical activation of the filler grains were used during the  course of the research.A simplex-centroid experiment design is  applied for this purpose. The composite binder was subjected to  mechanochemical activation. Samples were made by vibration-pressing from a concrete mix with a cone draught of 2 cm.Results. The grain composition of heat-resistant concrete is proved  to be the most important variable factor, regulating which the  properties of concrete can be varied. The compositions of heat- resistant basaltic concrete with activated composite binder having a  maximum application temperature of 700 ºС are developed. The  influence of the grain composition of the basaltic filler on the  properties of basaltic concrete using mathematical experiment planning methods is determined. The regression equations for the ultimate tensile strength and bending stress of basaltic concrete are  obtained for heating temperature of 700ºC.Conclusion. The granulometric composition of heat-resistant basaltic concrete based on the activated binder is optimised for basic physical and technical properties. The optimal granulometric  design of the composition of heat-resistant concrete indicates that as the coarse fraction (particles greater than 0.63 mm in the filler  composition increases, the ultimate tensile strength and bending  stress of heatresistant basaltic concrete is increased

  15. Ballistic Impact Resistance of Plain Woven Kenaf/Aramid Reinforced Polyvinyl Butyral Laminated Hybrid Composite

    Directory of Open Access Journals (Sweden)

    Suhad D. Salman

    2016-07-01

    Full Text Available Traditionally, the helmet shell has been used to provide protection against head injuries and fatalities caused by ballistic threats. In this study, because of the high cost of aramid fibres and the necessity for environmentally friendly alternatives, a portion of aramid was replaced with plain woven kenaf fibre, with different arrangements and thicknesses, without jeopardising the requirements demanded by U.S. Army helmet specifications. Furthermore, novel helmets were produced and tested to reduce the dependency on the ballistic resistance components. Their use could lead to helmets that are less costly and more easily available than conventional helmet armour. The hybrid materials subjected to ballistic tests were composed of 19 layers and were fabricated by the hot press technique using different numbers and configurations of plain woven kenaf and aramid layers. In the case of ballistic performance tests, a positive effect was found for the hybridisation of kenaf and aramid laminated composites.

  16. Grain boundary composition and irradiation-assisted stress corrosion cracking resistance in Type 348 stainless steel

    International Nuclear Information System (INIS)

    Jacobs, A.J.; Wozadlo, G.P.; Nakata, K.

    1994-01-01

    Scanning transmission electron microscopy (STEM) analyses, in-reactor swelling mandrel tests, and laboratory constant extension rate tensile (CERT) tests were conducted on nine custom type 348 (UNS S34800) stainless steel (SS) alloys in an attempt to correlate grain boundary composition with irradiation-assisted stress corrosion cracking (IASCC) resistance. Phosphorus (P) enrichment showed the best correlation with in-reactor test results, and chromium (Cr) depletion showed the best correlation with laboratory results. Silicon (Si) and P enrichment were found to depend quantitatively on the bulk concentrations of these elements. The amount of Cr depletion seemed dependent at least partially on the amounts of Si and/or P enrichment. Si and P enrichment and Cr depletion were suppressed by higher carbon (C) contents, such as that present in commercial-purity type 348 SS

  17. Contribution to the study of the influence of zinc bath composition on corrosion resistance of coatings obtained by galvanization

    International Nuclear Information System (INIS)

    Cabrillac, Claude

    1969-01-01

    This research thesis deals with the influence of zinc purity on the corrosion resistance of a coating obtained by galvanization, and on its effect on cathodic protection. This study therefore addresses methods and tests processes (notably salt spray test) aiming at assessing the efficiency of steel protection by hot galvanization, and aims at highlighting the influence of galvanization bath purity or composition on corrosion resistance of galvanized layers

  18. Improved Corrosion and Abrasion Resistance of Organic-Inorganic Composite Coated Electro-galvanized Steels for Digital TV Panels

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Du-Hwan; Noh, Sang-Geol; Park, Jong-Tae; Kang, Choon-Ho [POSCO Technical Research Laboratories, Pohang (Korea, Republic of)

    2015-10-15

    Recently, household electronic industries require environmentally-friendly and highly functional steels in order to enhance the quality of human life. Customers especially require both excellent corrosion and abrasion resistant anti-fingerprint steels for digital TV panels. Thus POSCO has developed new functional electro-galvanized steels, which have double coated layers with organic-inorganic composites on the zinc surface of the steel for usage as the bottom chassis panel of TVs. The inorganic solution for the bottom layer consists of inorganic phosphate, magnesium, and zirconium compounds with a small amount of epoxy binder, and affords both improved adhesion properties by chemical conversion reactions and corrosion resistance due to a self-healing effect. The composite solution for the top layer was prepared by fine dispersion of organic-inorganic ingredients that consist of a urethane modified polyacrylate polymer, hardener, silica sol and a titanium complex inhibitor in aqueous media. Both composite solutions were coated on the steel surface by using a roll coater and then cured through an induction furnace in the electro-galvanizing line. New anti-fingerprint steel was evaluated for quality performance through such procedures as the salt spray test for corrosion resistance, tribological test for abrasion resistance, and conductivity test for surface electric conductance regarding to both types of polymer resin and coating weight of composite solution. New composite coated anti-fingerprint steels afford both better corrosion resistance and abrasion properties compared to conventional anti-fingerprint steel that mainly consists of acrylate polymers. Detailed discussions of both composite solutions and experimental results suggest that urethane modifications of acrylate polymers of composite solutions play a key role in enhanced quality performances.

  19. Microstructure and wear resistance of a laser clad TiC reinforced nickel aluminides matrix composite coating

    International Nuclear Information System (INIS)

    Chen, Y.; Wang, H.M.

    2004-01-01

    Wear resistant TiC/(NiAl-Ni 3 Al) composite coating was fabricated on a substrate of electrolyzed nickel by laser cladding using Ni-Al-Ti-C alloy powders. The laser clad coating is metallurgically bonded to the substrate and has a homogenous fine microstructure consisting of the flower-like equiaxed TiC dendrite and the dual phase matrix of NiAl and Ni 3 Al. The intermetallic matrix composite coating exhibits excellent wear resistance under both room- and high-temperature sliding wear test conditions due to the high hardness of TiC coupled with the strong atomic bonds of intermetallic matrix

  20. Data on post irradiation experiments of heat resistant ceramic composite materials. PIE for 97M-13A

    Energy Technology Data Exchange (ETDEWEB)

    Baba, Shin-ichi; Ishihara, Masahiro; Souzawa, Shizuo [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment; Sekino, Hajime [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2003-03-01

    The research on the radiation damage mechanism of heat resistant ceramic composite materials is one of the research subjects of the innovative basic research in the field of high temperature engineering, using the High Temperature engineering Test Reactor (HTTR). Three series of irradiation tests on the heat resistant ceramic composite materials, first to third irradiation test program, were carried out using the Japan Material Testing Reactor (JMTR). This is a summary report on the first irradiation test program; irradiation induced dimensional change, thermal expansion coefficient, X-ray diffraction and {gamma}-ray spectrum are reported. (author)

  1. Superior high creep resistance of in situ nano-sized TiCx/Al-Cu-Mg composite.

    Science.gov (United States)

    Wang, Lei; Qiu, Feng; Zhao, Qinglong; Zha, Min; Jiang, Qichuan

    2017-07-03

    The tensile creep behavior of Al-Cu-Mg alloy and its composite containing in situ nano-sized TiC x were explored at temperatures of 493 K, 533 K and 573 K with the applied stresses in the range of 40 to 100 MPa. The composite reinforced by nano-sized TiC x particles exhibited excellent creep resistance ability, which was about 4-15 times higher than those of the unreinforced matrix alloy. The stress exponent of 5 was noticed for both Al-Cu-Mg alloy and its composite, which suggested that their creep behavior was related to dislocation climb mechanism. During deformation at elevated temperatures, the enhanced creep resistance of the composite was mainly attributed to two aspects: (a) Orowan strengthening and grain boundary (GB) strengthening induced by nano-sized TiC x particles, (b) θ' and S' precipitates strengthening.

  2. Compartemented fibres : The concept of multiple self-healing in advanced fibre composites

    NARCIS (Netherlands)

    Prajer, M.; Wu, X.; Garcia Espallargas, S.J.; Van der Zwaag, S.

    2013-01-01

    Polymers reinforced with high performance fibres are successfully replacing metal alloys in lightweight aircraft structures. A critical factor in structural design is the resistance of a structure to progressive damage which develops during its service time. The brittle nature of matrix cracking is

  3. Triclosan-immobilized polyamide thin film composite membranes with enhanced biofouling resistance

    Science.gov (United States)

    Park, Sang-Hee; Hwang, Seon Oh; Kim, Taek-Seung; Cho, Arah; Kwon, Soon Jin; Kim, Kyoung Taek; Park, Hee-Deung; Lee, Jung-Hyun

    2018-06-01

    We report on a strategy to improve biofouling resistance of a polyamide (PA) thin-film composite (TFC) reverse osmosis (RO) membrane via chemically immobilizing triclosan (TC), known as a common organic biocide, on its surface. To facilitate covalent attachment of TC on the membrane surface, TC was functionalized with amine moiety to prepare aminopropyl TC. Then, the TC-immobilized TFC (TFC-TC) membranes were fabricated through a one-step amide formation reaction between amine groups of aminopropyl TC and acyl chloride groups present on the PA membrane surface, which was confirmed by high-resolution XPS. Strong stability of the immobilized TC was also confirmed by a hydraulic washing test. Although the TFC-TC membrane showed slightly reduced separation performance compared to the pristine control, it still maintained a satisfactory RO performance level. Importantly, the TFC-TC membrane exhibited excellent antibacterial activity against both gram negative (E. coli and P. aeruginosa) and gram positive (S. aureus) bacteria along with greatly enhanced resistance to biofilm formation. Our immobilization approach offers a robust and relatively benign strategy to control biofouling of functional surfaces, films and membranes.

  4. Proof of the concept to use a malignant B cell line drug screen strategy for identification and weight of melphalan resistance genes in multiple myeloma.

    Directory of Open Access Journals (Sweden)

    Martin Bøgsted

    Full Text Available In a conceptual study of drug resistance we have used a preclinical model of malignant B-cell lines by combining drug induced growth inhibition and gene expression profiling. In the current report a melphalan resistance profile of 19 genes were weighted by microarray data from the MRC Myeloma IX trial and time to progression following high dose melphalan, to generate an individual melphalan resistance index. The resistance index was subsequently validated in the HOVON65/GMMG-HD4 trial data set to prove the concept. Biologically, the assigned resistance indices were differentially distributed among translocations and cyclin D expression classes. Clinically, the 25% most melphalan resistant, the intermediate 50% and the 25% most sensitive patients had a median progression free survival of 18, 32 and 28 months, respectively (log-rank P-value  = 0.05. Furthermore, the median overall survival was 45 months for the resistant group and not reached for the intermediate and sensitive groups (log-rank P-value  = 0.003 following 38 months median observation. In a multivariate analysis, correcting for age, sex and ISS-staging, we found a high resistance index to be an independent variable associated with inferior progression free survival and overall survival. This study provides clinical proof of concept to use in vitro drug screen for identification of melphalan resistance gene signatures for future functional analysis.

  5. Application of bridging-law concepts to short-fibre composites

    DEFF Research Database (Denmark)

    Lindhagen, J.E.; Gamstedt, Kristofer; Berglund, L.A.

    2000-01-01

    This is the third paper in a series of four where notch sensitivity, fracture energy and bridging laws are studied in short-fibre polymer composites. Here, bridging laws are derived from experimental crack-opening profiles in centre-hole notched tensile specimens. The materials studied are three...... types of commercial glass-mat composites with different reinforcement structures and matrices. The materials have softening bridging laws and the calculated fracture energies from bridging laws are in good agreement with values determined directly by experiment. The calculated maximum local bridging...

  6. Role of polymeric binders on mechanical behavior and cracking resistance of silicon composite electrodes during electrochemical cycling

    Science.gov (United States)

    Li, Dawei; Wang, Yikai; Hu, Jiazhi; Lu, Bo; Dang, Dingying; Zhang, Junqian; Cheng, Yang-Tse

    2018-05-01

    This work focuses on understanding the role of various binders, including sodium alginate (SA), Nafion, and polyvinylidene fluoride (PVDF), on the mechanical behavior and cracking resistance of silicon composite electrodes during electrochemical cycling. In situ curvature measurement of bilayer electrodes, consisting of a silicon-binder-carbon black composite layer on a copper foil, is used to determine the effects of binders on bending deformation, elastic modulus, and stress on the composite electrodes. It is found that the lithiation induced curvature and the modulus of the silicon/SA electrodes are larger than those of electrodes with Nafion and PVDF as binders. Although the modulus of Nafion is smaller than that of PVDF, the curvature and the modulus of silicon/Nafion composite are larger than those of silicon/PVDF electrodes. The moduli of all three composites decrease not only during lithiation but also during delithiation. Based on the measured stress and scanning electron microscopy observations of cracking in the composite electrodes, we conclude that the stress required to crack the composite electrodes with SA and Nafion binders is considerably higher than that of the silicon/PVDF electrode during electrochemical cycling. Thus, the cracking resistance of silicon/SA and silicon/Nafion composite electrodes is higher than that of silicon/PVDF electrodes.

  7. Materials, Manufacturing, and Test Development of a Composite Fan Blade Leading Edge Subcomponent for Improved Impact Resistance

    Science.gov (United States)

    Miller, Sandi G.; Handschuh, Katherine; Sinnott, Matthew J.; Kohlman, Lee W.; Roberts, Gary D.; Martin, Richard E.; Ruggeri, Charles R.; Pereira, J. Michael

    2015-01-01

    Application of polymer matrix composite materials for jet engine fan blades is becoming attractive as an alternative to metallic blades; particularly for large engines where significant weight savings are recognized on moving to a composite structure. However, the weight benefit of the composite is offset by a reduction of aerodynamic efficiency resulting from a necessary increase in blade thickness; relative to the titanium blades. Blade dimensions are largely driven by resistance to damage on bird strike. Further development of the composite material is necessary to allow composite blade designs to approximate the dimensions of a metallic fan blade. The reduction in thickness over the state of the art composite blades is expected to translate into structural weight reduction, improved aerodynamic efficiency, and therefore reduced fuel consumption. This paper presents test article design, subcomponent blade leading edge fabrication, test method development, and initial results from ballistic impact of a gelatin projectile on the leading edge of composite fan blades. The simplified test article geometry was developed to realistically simulate a blade leading edge while decreasing fabrication complexity. Impact data is presented on baseline composite blades and toughened blades; where a considerable improvement to impact resistance was recorded.

  8. Analysis of impact resistance of composite fan blade. Fukugozai fan blade no taishogekisei no kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Miyachi, T; Okumura, H; Otake, K; Sofue, Y [Japan Society for Aeronautical and Space Sciences, Tokyo (Japan)

    1992-01-05

    Numerical analysis of impact response was carried out when a bird strike was simulated to study the applicability of fiber reinforced composite material to fan blades for turbo-fan engines. The validity of the numerical analysis was verified by comparing the analyzed results with impact tested results of a fan-blade model of Ti-alloy. The impact resistance was studied by applying this method to fan blades of composite materials such as carbon fiber, epoxy resin and carbon-silicate fiber reinforced Ti-alloy. The finite element method was used for the analysis by dividing the model into triangular flat elements. The relation between the impact load, the deformation of blade and the strain, the natural frequency characteristics, the elastic modulus and hetrogeneity of blade were considered to analyze the impact response. The impact load by the strike of 1.5 lbs bird is very severe to the fan blades for turbo-fan engines having the thrust of 5 ton class. 23 refs., 23 figs., 3 tabs.

  9. Evaluating the thermal damage resistance of graphene/carbon nanotube hybrid composite coatings

    Science.gov (United States)

    David, L.; Feldman, A.; Mansfield, E.; Lehman, J.; Singh, G.

    2014-03-01

    We study laser irradiation behavior of multiwalled carbon nanotubes (MWCNT) and chemically modified graphene (rGO)-composite spray coatings for use as a thermal absorber material for high-power laser calorimeters. Spray coatings on aluminum test coupon were exposed to increasing laser irradiance for extended exposure times to quantify their damage threshold and optical absorbance. The coatings, prepared at varying mass % of MWCNTs in rGO, demonstrated significantly higher damage threshold values at 2.5 kW laser power at 10.6 μm wavelength than carbon paint or MWCNTs alone. Electron microscopy and Raman spectroscopy of irradiated specimens show that the coating prepared at 50% CNT loading endure at least 2 kW.cm-2 for 10 seconds without significant damage. The improved damage resistance is attributed to the unique structure of the composite in which the MWCNTs act as an efficient absorber of laser light while the much larger rGO sheets surrounding them, dissipate the heat over a wider area.

  10. The effect of N-stearoylethanolamine on plasma lipid composition in rats with experimental insulin resistance

    Directory of Open Access Journals (Sweden)

    O. V. Onopchenko

    2015-02-01

    Full Text Available A model of insulin resistance (IR, induced by prolonged high fat diet with high content of saturated fats was used to investigate the effect of N-stearoylethanolamine (NSE on the composition of free fatty acids (FFA, plasma lipoprotein spectrum and content of proinflammatory cytokine TNFα in rats. The results of this work showed a rise in the content of monounsaturated fatty acids (18:1 n-9 and a reduction in the level of polyunsaturated fatty acids (20:4 n-6 in plasma of rats with experimental IR. These findings are accompanied by the increased TNFα production and significant changes in plasma lipoprotein profile of rats with the fat overload. Particularly, a decreased high-density lipoprotein (HDL cholesterol level and increased low-density (LDL and very low-density lipoprotein (VLDL cholesterol level were detected. The NSE administration to obese rats with IR restored the content of mono- and polyunsaturated FFA, increased HDL cholesterol content and reduced LDL cholesterol level. In addition, the IR rats treated with NSE showed normalization in the serum TNFα level. Our results showed the restoration of plasma lipid profile under NSE administration in rats with obesity-induced IR. Considering the fact that plasma lipid composition displays the lipid metabolism in general, the NSE actions may play a significant role in the prevention of IR-associated complications.

  11. New Concept of Designing Composite Fuel for Fast Reactors with Closing Fuel Cycle

    International Nuclear Information System (INIS)

    Savchenko, A.; Vatulin, A.; Uferov, O.; Kulakov, G.; Sorokin, V.

    2013-01-01

    For fast reactors a novel type of promising composite U-PuO2 fuel is proposed which is based on dispersion fuel elements. Basic approach to fuel element development - separated operations of fabricating uranium meat fuel element and introducing into it Pu or MA dioxides powder, that results in minimizing dust forming operations in fuel element fabrication. Novel fuel features higher characteristics in comparison to metallic or MOX fuel its fabrication technology is readily accomplished and is environmentally clean. A possibility is demonstrated of fabricating coated steel claddings to protect from interaction with fuel and fission products when use standard rod type MOX or metallic U-Pu-Zr fuel. Novel approach to reprocessing of composite fuel is demonstrated, which allows to separate uranium from burnt plutonium as well as the newly generated fissile plutonium from burnt one without chemical processes, which simplifies the closing of the nuclear fuel cycle. Novel composite fuel combines the advantages of metallic and ceramic types of fuel and has high uranium density that allows also to implicate it in BREST types reactor with conversion ratio more than 1. Peculiarities of closing nuclear cycle with composite fuel are demonstrated that allows more effective re-usage of generated Pu as well as, minimizing r/a wastes by incineration of MA in specially developed IMF design

  12. An Abstract Interaction Concept for Designing Interaction Behaviour of Service Compositions

    NARCIS (Netherlands)

    Dirgahayu, T.; Quartel, Dick; van Sinderen, Marten J.; Mertins, Kai; Ruggaber, Rainer; Popplewell, Keith; Xu, Xiaofei

    2008-01-01

    In a service composition, interaction behaviour specifies an information exchange protocol that must be complied with in order to guarantee interoperability between services. Interaction behaviour can be designed using a top-down design approach utilising high abstraction levels to control its

  13. New concepts in the abstract format of the Compositional Interchange Format

    NARCIS (Netherlands)

    D.A. van Beek; P.J. Collins (Pieter); D.E. Nadales Agut; J.E. Rooda (Jacobus); R.R.H. Schiffelers; A. Giua; M. Silva (Manuel); J. Zaytoon

    2009-01-01

    textabstractThe compositional interchange format for hybrid systems (CIF) supports inter-operability of a wide range of tools by means of model transformations to and from the CIF. Work on the CIF takes place in the FP7 Multiform project, and in several other European projects. The CIF consists of

  14. Muscle wasting and resistance of muscle anabolism: the "anabolic threshold concept" for adapted nutritional strategies during sarcopenia.

    Science.gov (United States)

    Dardevet, Dominique; Rémond, Didier; Peyron, Marie-Agnès; Papet, Isabelle; Savary-Auzeloux, Isabelle; Mosoni, Laurent

    2012-01-01

    Skeletal muscle loss is observed in several physiopathological situations. Strategies to prevent, slow down, or increase recovery of muscle have already been tested. Besides exercise, nutrition, and more particularly protein nutrition based on increased amino acid, leucine or the quality of protein intake has generated positive acute postprandial effect on muscle protein anabolism. However, on the long term, these nutritional strategies have often failed in improving muscle mass even if given for long periods of time in both humans and rodent models. Muscle mass loss situations have been often correlated to a resistance of muscle protein anabolism to food intake which may be explained by an increase of the anabolic threshold toward the stimulatory effect of amino acids. In this paper, we will emphasize how this anabolic resistance may affect the intensity and the duration of the muscle anabolic response at the postprandial state and how it may explain the negative results obtained on the long term in the prevention of muscle mass. Sarcopenia, the muscle mass loss observed during aging, has been chosen to illustrate this concept but it may be kept in mind that it could be extended to any other catabolic states or recovery situations.

  15. New concept of composite strengthening in Co-Re based alloys for high temperature applications in gas turbines

    Energy Technology Data Exchange (ETDEWEB)

    Mukherji, D.; Roesler, J.; Fricke, T.; Schmitz, F. [Technische Univ. Braunschweig (DE). Inst. fuer Werkstoffkunde (IfW); Piegert, S. [Siemens AG, Berlin (DE). Energy Sector (F PR GT EN)

    2010-07-01

    High temperature material development is mainly driven by gas turbine needs. Today, Ni-based superalloys are the dominant material class in the hot section of turbines. Material development will continue to push the maximum service temperature of Ni-superalloys upwards. However, this approach has a fundamental limit and can not be sustained indefinitely, as the Ni-superalloys are already used very close to their melting point. Within the frame work of a DFG Forschergruppe program (FOR 727) - ''Beyond Ni-base Superalloys'' - Co-Re based alloys are being developed as a new generation of high temperature materials that can be used at +100 C above single crystal Ni-superalloys. Along with other strengthening concepts, hardening by second phase is explored to develop a two phase composite alloy. With quaternary Co-Re-Cr-Ni alloys we demonstrate this development concept, where Co{sub 2}Re{sub 3}-type {sigma} phase is used in a novel way as the hardening phase. Thermodynamic calculation was used for designing model alloy compositions. (orig.)

  16. Experimental and simulation of split semi-torus key in PVC foam core to improve the debonding resistance of composite sandwich panel

    Science.gov (United States)

    Juliyana, M.; Santhana Krishnan, R.

    2018-02-01

    The sandwich composite panels consisting of facesheet and core material are used as a primary structural member for aerospace, civil and marine areas due to its high stiffness to weight ratio. But the debonding nature of facesheet from the foam core under shear loading conditions leads to failure of the composite structure. To inhibit the debonding, an innovative methodology of introducing semi-torus key is used in the present study. The polyvinyl chloride foam core(PVC) is grooved and filled with semi-torus shaped chopped strand prepregs which are sandwiched between alternate layers of woven roven(WR) and chopped strand mat(CSM) skins by vacuum infusion process. The sandwich panel manufactured with semi-torus keys is evaluated regarding experimental and numerical simulations under shear loading conditions. The present innovative concept delays the debonding between face-sheet and foam core with enhancement the shear load carrying capability as the initial stiffness is higher than the conventional model. Also, the shear behaviour of the proposed concept is in good agreement with experimental results. The split semi-torus keys sustain the shear failure resulting in resistance to debonding capability.

  17. Modified resistivity-strain behavior through the incorporation of metallic particles in conductive polymer composite fibers containing carbon nanotubes

    NARCIS (Netherlands)

    Lin, L.; Deng, H.; Gao, X.; Zhang, S.M.; Bilotti, E.; Peijs, A.A.J.M.; Fu, Q.

    2013-01-01

    Eutectic metal particles and carbon nanotubes are incorporated into a thermoplastic polyurethane matrix through a simple but efficient method, melt compounding, to tune the resistivity-strain behavior of conductive polymer composite (CPC) fibers. Such a combination of conductive fillers is rarely

  18. Altered skeletal muscle fiber composition and size precede whole-body insulin resistance in young men with low birth weight

    DEFF Research Database (Denmark)

    Jensen, Christine B; Storgaard, Heidi; Madsbad, Sten

    2007-01-01

    CONTEXT: Low birth weight (LBW), a surrogate marker of an adverse fetal milieu, is linked to muscle insulin resistance, impaired insulin-stimulated glycolysis, and future risk of type 2 diabetes. Skeletal muscle mass, fiber composition, and capillary density are important determinants of muscle...

  19. Ex vivo fracture resistance of direct resin composite complete crowns with and without posts on maxillary premolars.

    NARCIS (Netherlands)

    Fokkinga, W.A.; Bell, A.M. Le; Kreulen, C.M.; Lassila, L.V.; Vallittu, P.K.; Creugers, N.H.J.

    2005-01-01

    AIM: To investigate ex vivo the fracture resistance and failure mode of direct resin composite complete crowns with and without various root canal posts made on maxillary premolars. METHODOLOGY: The clinical crowns of 40 human extracted single-rooted maxillary premolars were sectioned at the

  20. In vitro antibacterial activity of porous TiO2-Ag composite layers against methicillin-resistant Staphylococcus aureus

    NARCIS (Netherlands)

    Necula, Bogdan S.; Fratila-Apachitei, Lidy E.; Zaat, Sebastian A. J.; Apachitei, Iulian; Duszczyk, Jurek

    2009-01-01

    The aim of this study was the synthesis of a porous TiO(2)-Ag composite coating and assessment of its in vitro bactericidal activity against methicillin-resistant Staphylococcus aureus. The coating was produced by plasma electrolytic oxidation of Ti-6Al-7Nb medical alloy in a calcium acetate/calcium

  1. Biological degradation of wood-plastic composites (WPC) and strategies for improving the resistance of WPC against biological decay

    Science.gov (United States)

    Anke Schirp; Rebecca E. Ibach; David E. Pendleton; Michael P. Wolcott

    2008-01-01

    Much of the research on wood-plastic composites (WPC) has focused on formulation development and processing while high biological durability of the material was assumed. The gap between assumption and knowledge in biodeterioration of WPC needs to be reduced. Although some information on the short-term resistance of WPC against biological degradation is available, long-...

  2. Oxygen plasma treatment and deposition of CNx on a fluorinated polymer matrix composite for improved erosion resistance

    International Nuclear Information System (INIS)

    Muratore, C.; Korenyi-Both, A.; Bultman, J. E.; Waite, A. R.; Jones, J. G.; Storage, T. M.; Voevodin, A. A.

    2007-01-01

    The use of polymer matrix composites in aerospace propulsion applications is currently limited by insufficient resistance to erosion by abrasive media. Erosion resistant coatings may provide necessary protection; however, adhesion to many high temperature polymer matrix composite (PMC) materials is poor. A low pressure oxygen plasma treatment process was developed to improve adhesion of CN x coatings to a carbon reinforced, fluorinated polymer matrix composite. Fullerene-like CN x was selected as an erosion resistant coating for its high hardness-to-elastic modulus ratio and elastic resilience which were expected to reduce erosion from media incident at different angles (normal or glancing) relative to the surface. In situ x-ray photoelectron spectroscopy was used to evaluate the effect of the plasma treatment on surface chemistry, and electron microscopy was used to identify changes in the surface morphology of the PMC substrate after plasma exposure. The fluorine concentration at the surface was significantly reduced and the carbon fibers were exposed after plasma treatment. CN x coatings were then deposited on oxygen treated PMC substrates. Qualitative tests demonstrated that plasma treatment improved coating adhesion resulting in an erosion resistance improvement of a factor of 2 compared to untreated coated composite substrates. The combination of PMC pretreatment and coating with CN x reduced the erosion rate by an order of magnitude for normally incident particles

  3. Analysis of the Effect of Surface Modification on Polyimide Composites Coated with Erosion Resistant Materials

    Science.gov (United States)

    Ndalama, Tchinga; Hirschfeld, Deidre; Sutter, James K. (Technical Monitor)

    2003-01-01

    The aim of this research is to enhance performance of composite coatings through modification of graphite-reinforced polyimide composite surfaces prior to metal bond coat/ hard topcoat application for use in the erosive and/or oxidative environments of advanced engines. Graphite reinforced polyimide composites, PMR-15 and PMR-II-50, formed by sheet molding and pre-pregging will be surface treated, overlaid with a bond coat and then coated with WC-Co. The surface treatment will include cleaning, RF plasma or ultraviolet light- ozone etching, and deposition of SiO(x) groups. These surface treatments will be studied in order to investigate and improve adhesion and oxidation resistance. The following panels were provided by NASA-Glenn Research Center(NASA-GRC): Eight compression molded PMR-II-50; 6 x 6 x 0.125 in. Two vacuum-bagged PMR-II-50; 12 x 12 x 0.125 in. Eight compression molded PMR-15; 6 x 6 x 0.125 in. One vacuum-bagged PMR-15; 12 x 12 x 0.125 in. All panels were made using a 12 x 12 in. T650-35 8HS (3K-tow) graphite fabric. A diamond-wafering blade, with deionized water as a cutting fluid, was used to cut PMR-II-50 and PMR-15 panels into 1 x 1 in. pieces for surface tests. The panel edges exhibiting delamination were used for the preliminary surface preparation tests as these would be unsuitable for strength and erosion testing. PMR-15 neat resin samples were also provided by NASA GRC. Surface profiles of the as-received samples were determined using a Dektak III Surface profile measuring system. Two samples of compression molded PMR-II-50 and PMR-15, vacuum-bagged PMR-II-50 and PMR-15 were randomly chosen for surface profile measurement according to ANSI/ASME B46.1. Prior to each measurement, the samples were blasted with compressed air to remove any artifacts. Five 10 mm-long scans were made on each sample. The short and long wavelength cutoff filter values were set at 100 and 1000 m, diamond stylus radius was 12.5 microns. Table 1 is a summary of the

  4. Ablation resistance and mechanical/conductive properties of ZrB{sub 2} reinforced carbon based composites

    Energy Technology Data Exchange (ETDEWEB)

    Li, X.T.; Shi, J.L.; Zhang, H.; Zhang, G.B.; Guo, Q.G.; Liu, L. [Chinese Academy of Sciences, Taiyuan (China)

    2007-02-15

    Zirconium diboride reinforced carbon (ZrB{sub 2}/C) particulate composites are prepared from petroleum coke, coal tar pitch, and ZrB{sub 2} powder by hot-pressing. The ablation, mechanical, thermal, and electrical properties of the composites are studied. Results show that the composites have excellent flexural strength and thermal conductivity, with highest values reaching 131 MPa and 161 W/mK for a 10% ZrB{sub 2} addition in raw materials. The electrical resistivity reduces rapidly with increasing amount of ZrB{sub 2}. The values of mass and linear ablation rates are lower in the composites than those measured for pure carbon, decreasing with increasing ZrB{sub 2} content, confirming that these materials are promising for ultrahigh temperature materials. Correlations between properties and microstructure of the composites are also discussed.

  5. A Feasibility Study into the Active Smart Patch Concept for Composite Bonded Repairs

    Science.gov (United States)

    2008-08-01

    devel- opment of the concept targets the problem of cracking at Forward Auxillary Spar Station (FASS) 281.28 in the F-111 Lower Wing Skin. As a first... Auxillary Spar Station (FASS) 281.28 in the lower wing skin of the RAAF F-111C aircraft. Involving primary structure and a critical flaw, the use of a...ASP targets the specific problem of cracking at Forward Auxillary Spar Station (FASS) 281.28 in the F-111 Lower Wing Skin. A prototype patch was

  6. Beta-lactam resistance in the gram negatives: increasing complexity of conditional, composite and multiply resistant phenotypes.

    Science.gov (United States)

    Iredell, Jon; Thomas, Lee; Espedido, Björn

    2006-12-01

    The greatest impact of microbiology data on clinical care is in the critically ill. Unfortunately, this is also the area in which microbiology laboratories are most often non-contributive. Attempts to move to rapid, culture-independent diagnostics are driven by the need to expedite urgent results. This is difficult in Gram-negative infection because of the complexity of the antibiotic resistance phenotype. Here, we discuss resistance to modern beta-lactams as a case in point. Recent outbreaks of transmissible carbapenem resistance among Gram-negative enteric pathogens in Sydney and Melbourne serve to illustrate the pitfalls of traditional phenotypical approaches. A better understanding of the epidemiology and mosaic nature of antibiotic resistance elements in the microflora is needed for us to move forward.

  7. Changes in muscle size and MHC composition in response to resistance exercise with heavy and light loading intensity

    DEFF Research Database (Denmark)

    Holm, Lars; Reitelseder, Søren; Pedersen, T.G.

    2008-01-01

    Muscle mass accretion is accomplished by heavy-load resistance training. The effect of light-load resistance exercise has been far more sparsely investigated with regard to potential effect on muscle size and contractile strength. We applied a resistance exercise protocol in which the same indivi...... in healthy young men. However, LL resistance training was inferior to HL training in evoking adaptive changes in muscle size and contractile strength and was insufficient to induce changes in MHC composition.......Muscle mass accretion is accomplished by heavy-load resistance training. The effect of light-load resistance exercise has been far more sparsely investigated with regard to potential effect on muscle size and contractile strength. We applied a resistance exercise protocol in which the same.......05) in HL but remained unchanged in LL (4 +/- 5%, not significant). Finally, MHC IIX protein expression was decreased with HL but not LL, despite identical total workload in HL and LL. Our main finding was that LL resistance training was sufficient to induce a small but significant muscle hypertrophy...

  8. Electro-thermo-mechanical coupling analysis of deep drawing with resistance heating for aluminum matrix composites sheet

    Science.gov (United States)

    Zhang, Kaifeng; Zhang, Tuoda; Wang, Bo

    2013-05-01

    Recently, electro-plastic forming to be a focus of attention in materials hot processing research area, because it is a sort of energy-saving, high efficient and green manufacturing technology. An electro-thermo-mechanical model can be adopted to carry out the sequence simulation of aluminum matrix composites sheet deep drawing via electro-thermal coupling and thermal-mechanical coupling method. The first step of process is resistance heating of sheet, then turn off the power, and the second step is deep drawing. Temperature distribution of SiCp/2024Al composite sheet by resistance heating and sheet deep drawing deformation were analyzed. During the simulation, effect of contact resistances, temperature coefficient of resistance for electrode material and SiCp/2024Al composite on temperature distribution were integrally considered. The simulation results demonstrate that Sicp/2024Al composite sheet can be rapidly heated to 400° in 30s using resistances heating and the sheet temperature can be controlled by adjusting the current density. Physical properties of the electrode materials can significantly affect the composite sheet temperature distribution. The temperature difference between the center and the side of the sheet is proportional to the thermal conductivity of the electrode, the principal cause of which is that the heat transfers from the sheet to the electrode. SiCp/2024Al thin-wall part can be intactly manufactured at strain rate of 0.08s-1 and the sheet thickness thinning rate is limited within 20%, which corresponds well to the experimental result.

  9. Composite Resin Dosimeters: A New Concept and Design for a Fibrous Color Dosimeter.

    Science.gov (United States)

    Kinashi, Kenji; Iwata, Takato; Tsuchida, Hayato; Sakai, Wataru; Tsutsumi, Naoto

    2018-04-11

    Polystyrene (PS)-based composite microfibers combined with a photochromic spiropyran dye, 1,3,3-trimethylindolino-6'-nitrobenzopyrylospiran (6-nitro BIPS), and a photostimulable phosphor, europium-doped barium fluorochloride (BaFCl:Eu 2+ ), were developed for the detection of X-ray exposure doses on the order of approximately 1 Gy. To produce the PS-based composite microfibers, we employed a forcespinning method that embeds a high concentration of phosphor in PS in a safe, inexpensive, and simple procedure. On the basis of the optimization of the forcespinning process, fibrous color dosimeters with a high radiation dose sensitivity of 1.2-4.4 Gy were fabricated. The color of the dosimeters was found to transition from white to blue in response to X-ray exposure. The optimized fibrous color dosimeter, made from a solution having a PS/6-nitro BIPS/BaFCl:Eu 2+ /C 2 Cl 4 ratio of 7.0/0.21/28.0/28.0 (wt %) and produced with a 290 mm distance between the needle and collectors, a 0.34 mm 23 G needle nozzle, and a spinneret rotational rate of 3000 rpm, exhibited sensitivity to a dose as low as 1.2 Gy. To realize practical applications, we manufactured the optimized fibrous color dosimeter into a clothlike color dosimeter. The clothlike color dosimeter was mounted on a stuffed bear, and its coloring behavior was demonstrated upon X-ray exposure. After exposure with X-ray, a blue colored and shaped in the form of the letter "[Formula: see text]" clearly appeared on the surface of the clothlike color dosimeter. The proposed fibrous color dosimeters having excellent workability will be an unprecedented dosimetry and contributed to all industries utilizing radiation dosimeters. This new fibrous "composite resin dosimeter" should be able to replace traditional, wearable, and individual radiation dose monitoring devices, such as film badges.

  10. Correlation of gut microbiota composition with resistance to experimental autoimmune encephalomyelitis in rats

    Directory of Open Access Journals (Sweden)

    Suzana Stanisavljevic

    2016-12-01

    Full Text Available Multiple sclerosis is a chronic inflammatory disease of the central nervous system (CNS. It is widely accepted that autoimmune response against the antigens of the CNS is the essential pathogenic force in the disease. It has recently become increasingly appreciated that activated encephalitogenic cells tend to migrate towards gut associated lymphoid tissues (GALT and that interrupted balance between regulatory and inflammatory immunity within the GALT might have decisive role in the initiation and propagation of the CNS autoimmunity. Gut microbiota composition and function has the major impact on the balance in the GALT. Thus, our aim was to perform analyses of gut microbiota in experimental autoimmune encephalomyelitis (EAE, an animal model of multiple sclerosis. Albino Oxford (AO rats that are highly resistant to EAE induction and Dark Agouti (DA rats that develop EAE after mild immunization were compared for gut microbiota composition in different phases after EAE induction. Microbial analyses of the genus Lactobacillus and related lactic acid bacteria showed higher diversity of Lactobacillus spp. in EAE-resistant AO rats, while some members of Firmicutes and Proteobacteria (Undibacterium oligocarboniphilum were detected only in faeces of DA rats at the peak of the disease (between 13 and 16 days after induction. Interestingly, Turicibacter sp. that was found exclusively in non-immunized AO, but not in DA rats in our previous study was detected in DA rats that remained healthy 16 days after induction. Similar observation was obtained for the members of Lachnospiraceae. As dominant presence of the members of Lachnospiraceae family in gut microbial community has been linked with mild symptoms of various diseases, it is tempting to assume that Turicibacter sp. and Lachnospiraceae contribute to the prevention of EAE development and the alleviation of the disease symptoms. Further, production of a typical regulatory cytokine interleukin-10 was

  11. Innovative fabrication processing of advanced composite materials concepts for primary aircraft structures

    Science.gov (United States)

    Kassapoglou, Christos; Dinicola, Al J.; Chou, Jack C.

    1992-01-01

    The autoclave based THERM-X(sub R) process was evaluated by cocuring complex curved panels with frames and stiffeners. The process was shown to result in composite parts of high quality with good compaction at sharp radius regions and corners of intersecting parts. The structural properties of the postbuckled panels fabricated were found to be equivalent to those of conventionally tooled hand laid-up parts. Significant savings in bagging time over conventional tooling were documented. Structural details such as cocured shear ties and embedded stiffener flanges in the skin were found to suppress failure modes such as failure at corners of intersecting members and skin stiffeners separation.

  12. Composite piping: basic materials, manufacturing methods, hydrolysis resistance. Bibliographical data and state of the art

    International Nuclear Information System (INIS)

    Pays, M.F.

    1997-01-01

    EDF has decided to replace traditional materials by glass reinforced plastic for the manufacture of certain PWR water piping. However, these are liable to in-service degradation through the hydrolysis of the operating conditions which can involve mechanical stresses or specific temperature and humidity conditions. These resins have been the subject of bibliographical surveys and laboratory experiments providing the following main results: the water diffusion in the selected thermoset resins (polyester, vinyl-ester, epoxy) can reach one percent in weight, according to the relative humidity and temperature; the water absorption is a reversible phenomenon, at the beginning and is followed by hydrolysis, an irreversible deterioration affecting the chemical functions of the polymeric chain. Thermally activated, the reaction limits the temperature for the use of these resins; polyester resins are made of a large number of ester bonds and are highly sensitive to hydrolysis. These resins can be classified on the basis of the alcohol and acid which they come acid. A possible hydrolytic degradation does not prevent from using these resins in humid environments. The cooling towers in Belleville, Nogent ad Chooz are equipped with water collecting channels made of polyester laminates which have behaved satisfactorily since their installation in 1982. In acid environments, even concentrated, resins have a better behavior than in a neutral medium. However, they can be liable to stress corrosion. Polyester resins ar not suitable for use in concentrated base media. Vinyl-ester resins are more appropriate for this purpose, although their resistance will be lower than in a neutral environment. When resins are used as a matrix for composites, the presence of glass fibers modifies their behavior. The physico-chemical protection of the fiber/matrix interfaces and of the surface of the glass itself through the sizing of the fibers plays key role in the durability of the composites, which

  13. Self healing in polymers and polymer composites. Concepts, realization and outlook: A review

    Directory of Open Access Journals (Sweden)

    2008-04-01

    Full Text Available Formation of microcracks is a critical problem in polymers and polymer composites during their service in structural applications. Development and coalescence of microcracks would bring about catastrophic failure of the materials and then reduce their lifetimes. Therefore, early sensing, diagnosis and repair of microcracks become necessary for removing the latent perils. In this context, the materials possessing self-healing function are ideal for long-term operation. Self-repairing polymers and polymer composites have attracted increasing research interests. Attempts have been made to develop solutions in this field. The present article reviews state-of-art of the achievements on the topic. According to the ways of healing, the smart materials are classified into two categories: (i intrinsic self-healing ones that are able to heal cracks by the polymers themselves, and (ii extrinsic in which healing agent has to be pre-embedded. The advances in this field show that selection and optimization of proper repair mechanisms are prerequisites for high healing efficiency. It is a challenging job to either invent new polymers with inherent crack repair capability or integrate existing materials with novel healing system.

  14. Concepts for improving the damage tolerance of composite compression panels. [aircraft structures

    Science.gov (United States)

    Rhodes, M. D.; Williams, J. G.

    1984-01-01

    The residual strength of specimens with damage and the sensitivity to damage while subjected to an applied inplane compression load were determined for flatplate specimens and blade-stiffened panels. The results suggest that matrix materials that fail by delamination have the lowest damage tolerance capability. Alternate matrix materials or laminates which are transversely reinforced suppress the delamination mode of failure and change the failure mode to transverse shear crippling which occurs at a higher strain value. Several damage-tolerant blade-stiffened panel design concepts are evaluated. Structural efficiency studies conducted show only small mass penalties may result from incorporating these damage-tolerant features in panel design. The implication of test results on the design of aircraft structures was examined with respect to FAR requirements.

  15. Electrostatic Assembly Preparation of High-Toughness Zirconium Diboride-Based Ceramic Composites with Enhanced Thermal Shock Resistance Performance.

    Science.gov (United States)

    Zhang, Baoxi; Zhang, Xinghong; Hong, Changqing; Qiu, Yunfeng; Zhang, Jia; Han, Jiecai; Hu, PingAn

    2016-05-11

    The central problem of using ceramic as a structural material is its brittleness, which associated with rigid covalent or ionic bonds. Whiskers or fibers of strong ceramics such as silicon carbide (SiC) or silicon nitride (Si3N4) are widely embedded in a ceramic matrix to improve the strength and toughness. The incorporation of these insulating fillers can impede the thermal flow in ceramic matrix, thus decrease its thermal shock resistance that is required in some practical applications. Here we demonstrate that the toughness and thermal shock resistance of zirconium diboride (ZrB2)/SiC composites can be improved simultaneously by introducing graphene into composites via electrostatic assembly and subsequent sintering treatment. The incorporated graphene creates weak interfaces of grain boundaries (GBs) and optimal thermal conductance paths inside composites. In comparison to pristine ZrB2-SiC composites, the toughness of (2.0%) ZrB2-SiC/graphene composites exhibited a 61% increasing (from 4.3 to 6.93 MPa·m(1/2)) after spark plasma sintering (SPS); the retained strength after thermal shock increased as high as 74.8% at 400 °C and 304.4% at 500 °C. Present work presents an important guideline for producing high-toughness ceramic-based composites with enhanced thermal shock properties.

  16. Microstructure Characterization and Wear-Resistant Properties Evaluation of an Intermetallic Composite in Ni–Mo–Si System

    Directory of Open Access Journals (Sweden)

    Boyuan Huang

    2017-02-01

    Full Text Available Intermetallic compounds have been studied for their potential application as structural wear materials or coatings on engineering steels. In the present work, a newly designed intermetallic composite in a Ni–Mo–Si system was fabricated by arc-melting process with commercially pure metal powders as starting materials. The chemical composition of this intermetallic composite is 45Ni–40Mo–15Si (at %, selected according to the ternary alloy diagram. The microstructure was characterized using optical microscopy (OM, scanning electron microscopy (SEM, X-ray diffraction (XRD, and energy dispersive spectroscopy (EDS, and the wear-resistant properties at room temperature were evaluated under different wear test conditions. Microstructure characterization showed that the composite has a dense and uniform microstructure. XRD results showed that the intermetallic composite is constituted by a binary intermetallic compound NiMo and a ternary Mo2Ni3Si metal silicide phase. Wear test results indicated that the intermetallic composite has an excellent wear-resistance at room-temperature, which is attributed to the high hardness and strong atomic bonding of constituent phases NiMo and Mo2Ni3Si.

  17. Temperature Dependence of Electrical Resistance of Woven Melt-Infiltrated SiCf/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Appleby, Matthew P.; Morscher, Gregory N.; Zhu, Dongming

    2016-01-01

    Recent studies have successfully shown the use of electrical resistance (ER)measurements to monitor room temperature damage accumulation in SiC fiber reinforced SiC matrix composites (SiCf/SiC) Ceramic Matrix Composites (CMCs). In order to determine the feasibility of resistance monitoring at elevated temperatures, the present work investigates the temperature dependent electrical response of various MI (Melt Infiltrated)-CVI (Chemical Vapor Infiltrated) SiC/SiC composites containing Hi-Nicalon Type S, Tyranno ZMI and SA reinforcing fibers. Test were conducted using a commercially available isothermal testing apparatus as well as a novel, laser-based heating approach developed to more accurately simulate thermomechanical testing of CMCs. Secondly, a post-test inspection technique is demonstrated to show the effect of high-temperature exposure on electrical properties. Analysis was performed to determine the respective contribution of the fiber and matrix to the overall composite conductivity at elevated temperatures. It was concluded that because the silicon-rich matrix material dominates the electrical response at high temperature, ER monitoring would continue to be a feasible method for monitoring stress dependent matrix cracking of melt-infiltrated SiC/SiC composites under high temperature mechanical testing conditions. Finally, the effect of thermal gradients generated during localized heating of tensile coupons on overall electrical response of the composite is determined.

  18. A Resistive Humidity Sensor Based on Nanostructured WO3-ZnO Composites

    Directory of Open Access Journals (Sweden)

    Karunesh Tiwari

    2011-11-01

    Full Text Available Paper reports morphological and humidity sensing studies of WO3 and WO3-ZnO composite pellets prepared in the weight % ratio of 10:1, 4:1 and 2:1 by solid-state reaction route. The pellets have been annealed at temperatures of 300-500 °C. XRD pattern shows peaks of ZnWO4 formed due to solid state reaction between WO3 and ZnO. SEM micrographs show that the sensing elements manifest porous structure. Granulation and tendency to agglomerate seen in the SEM micrograph are due to the presence of zinc ions in ZnWO4. Nanoparticles are having their sizes in the range 37-182 nm. The average Kelvin radius at 20˚C room temperature is 27 Ả. Humidity sensing application of the pellets has been studied in a humidity control cabinet. It is observed that as relative humidity increases, there is decrease in the resistance of pellets in the range 10-85 % RH. Sensing element of WO3-ZnO in 2:1 weight % ratio shows best results in 10-85 % relative humidity range. The average sensitivity of this sample is 1.25 MΩ/%RH. This sensing element shows good reproducibility, low hysteresis and less effect of aging.

  19. Biodegradation Resistance and Bioactivity of Hydroxyapatite Enhanced Mg-Zn Composites via Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Cijun Shuai

    2017-03-01

    Full Text Available Mg-Zn alloys have attracted great attention as implant biomaterials due to their biodegradability and biomechanical compatibility. However, their clinical application was limited due to the too rapid degradation. In the study, hydroxyapatite (HA was incorporated into Mg-Zn alloy via selective laser melting. Results showed that the degradation rate slowed down due to the decrease of grain size and the formation of protective layer of bone-like apatite. Moreover, the grain size continually decreased with increasing HA content, which was attributed to the heterogeneous nucleation and increased number of nucleation particles in the process of solidification. At the same time, the amount of bone-like apatite increased because HA could provide favorable areas for apatite nucleation. Besides, HA also enhanced the hardness due to the fine grain strengthening and second phase strengthening. However, some pores occurred owing to the agglomerate of HA when its content was excessive, which decreased the biodegradation resistance. These results demonstrated that the Mg-Zn/HA composites were potential implant biomaterials.

  20. Biodegradation Resistance and Bioactivity of Hydroxyapatite Enhanced Mg-Zn Composites via Selective Laser Melting.

    Science.gov (United States)

    Shuai, Cijun; Zhou, Yuanzhuo; Yang, Youwen; Feng, Pei; Liu, Long; He, Chongxian; Zhao, Mingchun; Yang, Sheng; Gao, Chengde; Wu, Ping

    2017-03-17

    Mg-Zn alloys have attracted great attention as implant biomaterials due to their biodegradability and biomechanical compatibility. However, their clinical application was limited due to the too rapid degradation. In the study, hydroxyapatite (HA) was incorporated into Mg-Zn alloy via selective laser melting. Results showed that the degradation rate slowed down due to the decrease of grain size and the formation of protective layer of bone-like apatite. Moreover, the grain size continually decreased with increasing HA content, which was attributed to the heterogeneous nucleation and increased number of nucleation particles in the process of solidification. At the same time, the amount of bone-like apatite increased because HA could provide favorable areas for apatite nucleation. Besides, HA also enhanced the hardness due to the fine grain strengthening and second phase strengthening. However, some pores occurred owing to the agglomerate of HA when its content was excessive, which decreased the biodegradation resistance. These results demonstrated that the Mg-Zn/HA composites were potential implant biomaterials.

  1. Dendrimeric Thin-Film Composite Membranes: Free Volume, Roughness, and Fouling Resistance

    KAUST Repository

    Phuoc, Duong

    2017-11-10

    Copolyamide films with a thickness from 50 to 780 nm were fabricated by interfacial polymerization between mixtures of m-phenylene diamine and primary amine-terminated polyamidoamine dendrimers (PAMAM) in the aqueous phase and trimesoyl chloride (TMC) in the organic phase. Different PAMAM generations (G0, d = 15 Å, Z = 4; G3, d = 36 Å, Z = 32; and G5, d = 54, Z = 128, where d is the measured diameter and Z is the number of terminal groups) and concentrations were used to obtain copolyamide films with different crosslinked structures. The influences of the concentration and degree of branching (PAMAM generation) on free volume were analysed via positon annihilation spectroscopy (PAS) and correlated with the separation properties of copolyamide films. Besides, surface and intrinsic properties of copolyamide films under different conditions were compared. The high hydrophilicity of PAMAM in the copolyamide network leads to the formation of a hydration layer on the copolyamide surface, which minimizes fouling. The separation performance of copolyamide membranes with various PAMAM networks was investigated in forward osmosis (FO) experiments. Understanding the correlation between the PAMAM structure/concentration, free volume, thickness, and surface intrinsic properties leads to the design of suitable fouling resistant thin-film composite membranes in a single interfacial polymerization process.

  2. An experimental estimation of the resistance against a high-temperature gas corrosion of C/C composite materials with protective plasma coating

    International Nuclear Information System (INIS)

    Babin, S.V.; Khripakov, E.V.

    2007-01-01

    Materials with well-defined structure has been proposed as corrosion- and erosion-resistant coating from the carbon-carbon composite. Experiments on heat and erosion resistance of plasma coatings at carbon-carbon composite materials demonstrate availability of multilayer with upper erosion resistant layer on the basis of aluminium oxide, intermediate layer on the basis of boron-containing components with aluminium additions and damping layer of silicon carbide. Multilayer protective coats offer demand service characteristics of details [ru

  3. Composite plasma electrolytic oxidation to improve the thermal radiation performance and corrosion resistance on an Al substrate

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Donghyun [Department of Materials Science and Engineering, Pusan National University, Busan 46241 (Korea, Republic of); Sung, Dahye [Department of Materials Science and Engineering, Pusan National University, Busan 46241 (Korea, Republic of); Korea Institute of Industrial Technology (KITECH), Busan 46742 (Korea, Republic of); Lee, Junghoon [Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030 (United States); Kim, Yonghwan [Korea Institute of Industrial Technology (KITECH), Busan 46742 (Korea, Republic of); Chung, Wonsub, E-mail: wschung1@pusan.ac.kr [Department of Materials Science and Engineering, Pusan National University, Busan 46241 (Korea, Republic of)

    2015-12-01

    Highlights: • Composite plasma electrolytic oxidation was performed using dispersed CuO particles in convectional PEO electrolyte. • Thermal radiation performance and corrosion resistance were examined by FT-IR spectroscopy and electrochemical methods, respectively. • Deposited copper oxide on the surface of the Al substrate was enhanced the corrosion resistance and the emissivity compared with the conventional PEO. - Abstract: A composite plasma electrolytic oxidation (PEO) was performed for enhancing the thermal radiation performance and corrosion resistance on an Al alloy by dispersing cupric oxide (CuO) particles in a conventional PEO electrolyte. Cu-based oxides (CuO and Cu{sub 2}O) formed by composite PEO increased the emissivity of the substrate to 0.892, and made the surface being dark color, similar to a black body, i.e., an ideal radiator. In addition, the corrosion resistance was analyzed using potentio-dynamic polarization and electrochemical impedance spectroscopy tests in 3.5 wt.% NaCl aqueous solution. An optimum condition of 10 ampere per square decimeter (ASD) current density and 30 min processing time produced appropriate surface morphologies and coating thicknesses, as well as dense Cu- and Al-based oxides that constituted the coating layers.

  4. Effect of length and diameter of fiber reinforced composite post (FRC on fracture resistance of remaining tooth structure

    Directory of Open Access Journals (Sweden)

    Mahdiyeh seifi

    2013-03-01

    Full Text Available Introduction: Post and core has been considered for endodontically treated tooth, especially in cases with severe damage crowns. Recently fiber reinforced composite posts (FRC post have been used in the treatment of endodontically treated teeth. Because the length and diameter of posts are effective in stress distribution, the purpose of this study is to evaluate the effect of length and diameter of FRC post on fracture resistance. Methods: In this experimental study, 36 glass fiber posts with combination of 7mm, 9mm, and 12mm length and 1.1mm, 1.3mm and 1.5mm diameter were divided into 9 groups of 4. These posts were cemented in root canals by Panavia. Samples were tested with 45° compressive forces for the evaluation of fracture resistance. Datas were analyzed using SPSS soft ware and One- way and Two-way ANOVA analyses. Results: Fracture resistance did not increase significantly with the effect of length and diameter simultaneously (P=0.85. Samples with 12mm length and 1.5mm diameter had the greatest fracture resistance (1023/33N±239/22. The minimum fracture resistance had occurred in post with 7mm length and 1.5mm diameter (503/13N ±69/18. Fracture resistance increased significantly by increasing the length and the same diameter. Conclusion: It can be concluded that fracture resistance is affected by the length and not the diameter of FRC post.

  5. Effect of different composite core materials on fracture resistance of endodontically treated teeth restored with FRC posts.

    Science.gov (United States)

    Panitiwat, Prapaporn; Salimee, Prarom

    2017-01-01

    This study evaluated the fracture resistance of endodontically treated teeth restored with fiber reinforced composite posts, using three resin composite core build-up materials, (Clearfil Photo Core (CPC), MultiCore Flow (MCF), and LuxaCore Z-Dual (LCZ)), and a nanohybrid composite, (Tetric N-Ceram (TNC)). Forty endodontically treated lower first premolars were restored with quartz fiber posts (D.T. Light-Post) cemented with resin cement (Panavia F2.0). Samples were randomly divided into four groups (n=10). Each group was built-up with one of the four core materials following its manufacturers' instructions. The teeth were embedded in acrylic resin blocks. Nickel-Chromium crowns were fixed on the specimens with resin cement. The fracture resistance was determined using a universal testing machine with a crosshead speed of 1 mm/min at 1350 to the tooth axis until failure occurred. All core materials used in the study were subjected to test for the flexural modulus according to ISO 4049:2009. One-way ANOVA and Bonferroni multiple comparisons test indicated that the fracture resistance was higher in the groups with CPC and MCF, which presented no statistically significant difference (p>0.05), but was significantly higher than in those with LCZ and TNC (paligned with the same tendency of fracture loads. Among the cores used in this study, the composite core with high filler content tended to enhance fracture thresholds of teeth restored with fiber posts more than others.

  6. Development of carbon/carbon composite control rod for HTTR. 2. Concept, specifications and mechanical test of materials

    International Nuclear Information System (INIS)

    Eto, Motokuni; Ishiyama, Shintaro; Fukaya, Kiyoshi; Saito, Tamotsu; Ishihara, Masahiro; Hanawa, Satoshi.

    1998-01-01

    A concept and specifications of carbon/carbon composite (C/C) control rod were proposed, aiming at the application of the material to the HTTR. The outer diameter and length of the control rod were kept as the same as those of the present control rod, i.e., 113 mm and 3094 mm, respectively. According to the concept, the rod consists of ten units which are connected in series using bolts. Then, the stresses generated by dead loads in the control rod elements were estimated and compared with the design strengths which were derived from the results of measurements of tensile, compressive, bending and shear strengths of two candidate materials, AC250 (Across Co.) and CX-270 (Toyo Tanso Co.). Design strength was preliminarily determined as one-third or one-fifth of the mean strength. Ratio of the design strength to generated stress for the AC250 (2D) was : Tensile stress in the outer sleeve tube, 66, tensile and shear stresses in the M16 bolt, 8.8 and 8.5, shear stress in the plug support bolt M8, 2.43. These results are believed to indicate the mechanical integrity of the control rod structure. Data available on the candidate materials were also compiled in the Appendix. (author)

  7. Advanced composites structural concepts and materials technologies for primary aircraft structures: Structural response and failure analysis

    Science.gov (United States)

    Dorris, William J.; Hairr, John W.; Huang, Jui-Tien; Ingram, J. Edward; Shah, Bharat M.

    1992-01-01

    Non-linear analysis methods were adapted and incorporated in a finite element based DIAL code. These methods are necessary to evaluate the global response of a stiffened structure under combined in-plane and out-of-plane loading. These methods include the Arc Length method and target point analysis procedure. A new interface material model was implemented that can model elastic-plastic behavior of the bond adhesive. Direct application of this method is in skin/stiffener interface failure assessment. Addition of the AML (angle minus longitudinal or load) failure procedure and Hasin's failure criteria provides added capability in the failure predictions. Interactive Stiffened Panel Analysis modules were developed as interactive pre-and post-processors. Each module provides the means of performing self-initiated finite elements based analysis of primary structures such as a flat or curved stiffened panel; a corrugated flat sandwich panel; and a curved geodesic fuselage panel. This module brings finite element analysis into the design of composite structures without the requirement for the user to know much about the techniques and procedures needed to actually perform a finite element analysis from scratch. An interactive finite element code was developed to predict bolted joint strength considering material and geometrical non-linearity. The developed method conducts an ultimate strength failure analysis using a set of material degradation models.

  8. A concept for fault tolerant design and improved availability of active composite elastic structures

    Science.gov (United States)

    Soeffker, D.; Wolters, K.; Krajcin, I.

    2005-05-01

    New functionalities, higher comfort and increasing performance requirements are often be solved by adding new technologies to existing (passive) solutions. Monitoring and control approaches uses additional sensors and actuators, new materials, microprocessors and new devices realizing new and improved functionalities. Two effects are becoming more and more interesting: (1) the lifetime of new actuators/materials strongly depends on the usage-history, (2) the functionality of the new composed systems depends on the fully functionality of all elements. In the consequence, the availability of such new systems is decreased by the number of elements and depends strongly on the use. These effects are known and act against new developments improving performance behavior also in mechanical engineering, automotive systems etc. This will be also the case for multifunctional composite or compound systems such as piezomaterials, magnetostrictive alloys or smart memory alloys (SMA) and is actually within the focus of the Structural-Health-Monitoring (SHM)-community. This contribution explains a new and systematically structured methodological approach to avoid and eliminate failures in mechatronical systems in an integrated and intelligent way to achieve a desirable or required amount of utilization in compliance with a defined failure rate. The result is an enhancement of the dependability of such a system.

  9. The concept of a composite perioperative quality index in kidney transplantation.

    Science.gov (United States)

    Taber, David J; McGillicuddy, John W; Bratton, Charles F; Lin, Angello; Chavin, Kenneth D; Baliga, Prabhakar K

    2014-04-01

    Public reporting of patient and graft outcomes in a national registry and close Centers for Medicare and Medicaid Services oversight has resulted in transplantation being a highly regulated surgical discipline. Despite this, transplantation surgery lacks comprehensive tracking and reporting of perioperative quality measures. Therefore, the aim of this study was to determine the association between a kidney transplantation centers' perioperative quality benchmarking and graft and patient outcomes. This was an analysis of 2011 aggregate data compiled from 2 national datasets that track outcomes from member hospitals and transplantation centers. The transplantation centers included in this study were composed of accredited US kidney transplantation centers that report data through the national registry and are associate members of the University HealthSystem Consortium. A total of 16,811 kidney transplantations were performed at 236 centers in the United States in 2011, of which 10,241 (61%) from 93 centers were included in the analysis. Of the 6 perioperative quality indicators, 3 benchmarked metrics were significantly associated with a kidney transplantation center's underperformance: mean ICU length of stay (C-statistic 0.731; p = 0.002), 30-day readmissions (C-statistic 0.697; p = 0.012) and in-hospital complications (C-statistic 0.785; p = 0.001). The composite quality index strongly correlated with inadequate center performance (C-statistic 0.854; p < 0.001, R(2) = 0.349). The centers in the lowest quartile of the quality index performed 2,400 kidney transplantations in 2011, which led to 2,640 more hospital days, 4,560 more ICU days, 120 more postoperative complications, and 144 more patients with 30-day readmissions, when compared with centers in the 3 higher-quality quartiles. An objective index of a transplantation center's quality of perioperative care is significantly associated with patient and graft survival. Copyright © 2014 American College of

  10. Fracture Resistance of Ceramic Laminate Veneers Bonded to Teeth with Class V Composite Fillings after Cyclic Loading

    Directory of Open Access Journals (Sweden)

    Leyla Sadighpour

    2018-01-01

    Full Text Available Purpose. Porcelain laminate veneers (PLVs are sometimes required to be used for teeth with composite fillings. This study examined the fracture strength of PLVs bonded to the teeth restored with different sizes of class V composite fillings. Materials and Methods. Thirty-six maxillary central incisors were divided into three groups (n=12: intact teeth (control and teeth with class V composite fillings of one-third or two-thirds of the crown height (small or large group, resp.. PLVs were made by using IPS e.max and bonded with a resin cement (RelyX Unicem. Fracture resistance (N was measured after cyclic loading (1 × 106 cycles, 1.2 Hz. For statistical analyses, one-way ANOVA and Tukey test were used (α=0.05. Results. There was a significant difference between the mean failure loads of the test groups (P=0.004, with the Tukey-HSD test showing lower failure loads in the large-composite group compared to the control (P=0.02 or small group (P=0.05. The control and small-composite groups achieved comparable results (P>0.05. Conclusions. Failure loads of PLVs bonded to intact teeth and to teeth with small class V composite fillings were not significantly different. However, extensive composite fillings could compromise the bonding of PLVs.

  11. Towards the improvement of the oxidation resistance of Nb-silicides in situ composites: A solid state diffusion approach

    International Nuclear Information System (INIS)

    Mathieu, S.; Knittel, S.; François, M.; Portebois, L.; Mathieu, S.; Vilasi, M.

    2014-01-01

    Highlights: •Local equilibrium is attained during oxidation at phase boundaries (steady state conditions). •A solid state diffusion model explains the oxidation mechanism of Nb-silicides composites. •The Nb ss fraction is not the only parameters governing the oxidation rate of Nb-silicides. •Aluminium increases the thermodynamic activity of Si in the Nb-silicides composites. •The results indicate the need to develop a Nb–Ti–Hf–Al–Cr–Si thermodynamic database. -- Abstract: The present study focuses on the oxidation mechanism of Nb-silicide composites and on the effect of the composition on the oxidation rate at 1100 °C. A theoretical approach is proposed based on experimental results and used to optimise the oxidation resistance. The growth model based on multiphase diffusion was experimentally tested and confirmed by manufacturing seven composites with different compositions. It was also found that the effect of the composition has to be evaluated at 1100 °C within a short time duration (50 h), where the oxide scale and the internal oxidation zone both grow according to parabolic kinetics

  12. Effect of domain size and interface characteristics on the impact resistance of selected polymer composites

    Science.gov (United States)

    Viratyaporn, Wantinee

    Nanocomposite technology has advanced considerably in recent years and excellent engineering properties have been achieved in numerous systems. In multiphase materials the enhancement of properties relies heavily on the nature at the interphase region between polymer domains and nanoparticle reinforcements. Strong adhesion between the phases provides excellent load-transfer and good mechanical elastic modulus and strength, whereas weak interaction contributes to crack deflection mechanisms and toughness. Polymer molecules are large and the presence of comparably sized filler particles affects chain gyration, which in turn influences the conformation of the polymer and the properties of the composite. Nanoparticles were incorporated into a poly(methyl methacrylate) matrix by means of in situ free radical (bulk) polymerization. Aluminum oxide and zinc oxide nanoparticles were added to study the effects of particle chemistry and shape on selected mechanical properties such as impact resistance, which showed significant improvement at a certain loading of zinc oxide. The elongated shape of zinc oxide particles appears to promote crack deflection processes and to introduce a pull-out mechanism similar to that observed in fiber composite systems. Moreover, the thermal stability of PMMA was improved with the addition of nanoparticles, apparently by steric hindrance of polymer chain motion and a second mechanism related to the dipole inducing effect of the oxide particles. The sensitivity of infrared spectroscopy to changes in molecular dipoles was used to study the nature of the polymer/particle interface. The results revealed some interesting aspects of the secondary bonds between polymers and oxides. Raman spectroscopy was used to investigate the extent of polymerization and changes in polymer conformation. A degree of polymerization of 93% was achieved in neat PMMA, and even when 5.0 v/o of PGMEA was introduced into the system no monomer was detected. However, when

  13. Effect of Volume Fraction of Particle on Wear Resistance of Al2O3/Steel Composites at Elevated Temperature

    Institute of Scientific and Technical Information of China (English)

    BAO Chong-gao; WANG En-ze; GAO Yi-min; XING Jian-dong

    2005-01-01

    Based on previous work,abrasive wear resistance of Al2 O3/steel composites with different Al2 O3 parti cle volume fraction (VOF) at 900 C was investigated.The experimental results showed that a suitable particle VOF is important to protect the metal matrix from wear at elevated temperature.Both too high and too low particle VOF lead to a poor abrasive wear because a bulk matrix is easily worn off by grits when it exceeds the suitable VOF and also because when VOF is low,the Al2O3 particles are easily dug out by grits during wearing as well.When the particle VOF is 39%,the wear resistance of tested composites is excellent.

  14. High Kinetic Energy Penetrator Shielding and High Wear Resistance Materials Fabricated with Boron Nitride Nanotubes (BNNTS) and BNNT Polymer Composites

    Science.gov (United States)

    Kang, Jin Ho (Inventor); Sauti, Godfrey (Inventor); Smith, Michael W. (Inventor); Jordan, Kevin C. (Inventor); Park, Cheol (Inventor); Bryant, Robert George (Inventor); Lowther, Sharon E. (Inventor)

    2015-01-01

    Boron nitride nanotubes (BNNTs), boron nitride nanoparticles (BNNPs), carbon nanotubes (CNTs), graphites, or combinations, are incorporated into matrices of polymer, ceramic or metals. Fibers, yarns, and woven or nonwoven mats of BNNTs are used as toughening layers in penetration resistant materials to maximize energy absorption and/or high hardness layers to rebound or deform penetrators. They can be also used as reinforcing inclusions combining with other polymer matrices to create composite layers like typical reinforcing fibers such as Kevlar.RTM., Spectra.RTM., ceramics and metals. Enhanced wear resistance and usage time are achieved by adding boron nitride nanomaterials, increasing hardness and toughness. Such materials can be used in high temperature environments since the oxidation temperature of BNNTs exceeds 800.degree. C. in air. Boron nitride based composites are useful as strong structural materials for anti-micrometeorite layers for spacecraft and space suits, ultra strong tethers, protective gear, vehicles, helmets, shields and safety suits/helmets for industry.

  15. Effect of chemical composition on corrosion resistance of Zircaloy fuel cladding tube for BWR

    International Nuclear Information System (INIS)

    Inagaki, Masahisa; Akahori, Kimihiko; Kuniya, Jirou; Masaoka, Isao; Suwa, Masateru; Maru, Akira; Yasuda, Teturou; Maki, Hideo.

    1990-01-01

    Effects of Fe and Ni contents on nodular corrosion susceptibility and hydrogen pick-up of Zircaloy were investigated. Total number of 31 Zr alloys having different chemical compositions; five Zr-Sn-Fe-Cr alloys, eight Zr-Sn-Fe-Ni alloys and eighteen Zr-Sn-Fe-Ni-Cr alloys, were melted and processed to thin plates for the corrosion tests in the environments of a high temperature (510degC) steam and a high temperature (288degC) water. In addition, four 450 kg ingots of Zr-Sn-Fe-Ni-Cr alloys were industrially melted and BWR fuel cladding tubes were manufactured through a current material processing sequence to study their producibility, tensile properties and corrosion resistance. Nodular corrosion susceptibility decreased with increasing Fe and Ni contents of Zircaloys. It was seen that the improved Zircaloys having Fe and Ni contents in the range of 0.30 [Ni]+0.15[Fe]≥0.045 (w%) showed no susceptibility to nodular corrosion. An increase of Fe content resulted in a decrease of hydrogen pick-up fraction in both steam and water environments. An increase of Fe and Ni content of Zircaloys in the range of Fe≤0.25 w% and Ni≤0.1 w% did not cause the changes in tensile properties and fabricabilities of fuel cladding tube. The fuel cladding tube of improved Zircaloy, containing more amount of Fe and Ni than the upper limit of Zircaloy-2 specification showed no susceptibility to nodular corrosion even in the 530degC steam test. (author)

  16. Determining the fracture resistance of fibre-reinforced glass matrix composites by means of the chevron-notch flexural technique

    Czech Academy of Sciences Publication Activity Database

    Boccaccini, A. R.; Kern, H.; Dlouhý, Ivo

    2001-01-01

    Roč. 308, 1/2 (2001), s. 111-117 ISSN 0921-5093 R&D Projects: GA ČR GV101/96/K264 Institutional research plan: CEZ:AV0Z2041904 Keywords : glass matrix composites * fracture toughness * chevron notch test Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 0.978, year: 2001

  17. Concept of the development of new type reactor and other nuclear technology in which nuclear-proliferation resistivity is taken into consideration

    International Nuclear Information System (INIS)

    Chang, Yoon I.

    2000-01-01

    As we start a new century in a new millennium, it is timely to look back at the last 50 years of nuclear energy development, and take a pause here to formulate the directions we need to take in the nuclear energy development for the next 50 years and beyond. The proliferation resistivity should be given a priority in the development of next-generation advanced reactor concepts, and there are three important principles to be considered in such efforts. The proliferation resistivity should be considered as a part of broader objectives, rather than a design goal by itself; the proliferation resistivity should be considered within the context of global institutional framework; and any technical proliferation resistivity features designed into the reactor system should be made intrinsic in nature. (author)

  18. Changes in body composition in heart failure patients after a resistance exercise program and branched chain amino acid supplementation.

    Science.gov (United States)

    Pineda-Juárez, Juan Antonio; Sánchez-Ortiz, Néstor Alonso; Castillo-Martínez, Lilia; Orea-Tejeda, Arturo; Cervantes-Gaytán, Rocío; Keirns-Davis, Candace; Pérez-Ocampo, Carlos; Quiroz-Bautista, Karla; Tenorio-Dupont, Mónica; Ronquillo-Martínez, Alberto

    2016-02-01

    Heart Failure (HF) is a complex syndrome, which can include the physiological, neural hormonal and metabolic complications known as "Cardiac Cachexia" (CC). In the development of CC there is a release of catabolic cytokines (Tumor Necrosis Factor-α, interleukins 1 and 6) that cause a decrease of fat free mass and fat mass. These changes in body composition might be reversed with a therapeutic combination of resistance exercise and branched chain amino acid supplementation (BCAA). Evaluate changes in body composition after a resistance exercise program and BCAA supplementation in patients with HF. In a randomized clinical trial with 3 month of follow-up anthropometric body composition analysis and stress tests were evaluated at the beginning and in the end of the study. Patients were divided into two groups; the experimental group performed the resistance exercise program and received 10 g/day BCAA supplementation, and the control group only performed the resistance exercise program. Both groups were provided with individualized diets and conventional medical treatment. Changes were found in hip circumference between the groups (p = 0.02), and muscle strength was increased in the experimental group (8%) and the control group (11.4%) with no difference between them. METS and VO2Max also increased in experimental and control groups (16.6% and 50.1% respectively). Regarding changes in symptoms, improvements in fatigue (45.4%), decubitus intolerance (21.8%) and dyspnea (25.4%) were observed in the overall sample. Improvements in physical and functional capacities are attributed to resistance exercise program but not to the BCAA supplementation. NCT02240511. Copyright © 2015 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

  19. Wear Resistant Thermal Sprayed Composite Coatings Based on Iron Self-Fluxing Alloy and Recycled Cermet Powders

    Directory of Open Access Journals (Sweden)

    Heikki SARJAS

    2012-03-01

    Full Text Available Thermal spray and WC-Co based coatings are widely used in areas subjected to abrasive wear. Commercial  cermet thermal spray powders for HVOF are relatively expensive. Therefore applying these powders in cost-sensitive areas like mining and agriculture are hindered. Nowadays, the use of cheap iron based self-fluxing alloy powders for thermal spray is limited. The aim of this research was to study properties of composite powders based on self-fluxing alloys and recycled cermets and to examine the properties of thermally sprayed (HVOF coatings from composite powders based on iron self-fluxing alloy and recycled cermet powders (Cr3C2-Ni and WC-Co. To estimate the properties of  recycled cermet powders, the sieving analysis, laser granulometry and morphology were conducted. For deposition of coatings High Velocity Oxy-Fuel spray was used. The structure and composition of powders and coatings were estimated by SEM and XRD methods. Abrasive wear performance of coatings was determined and compared with wear resistance of coatings from commercial powders. The wear resistance of thermal sprayed coatings from self-fluxing alloy and recycled cermet powders at abrasion is comparable with wear resistance of coatings from commercial expensive spray powders and may be an alternative in tribological applications in cost-sensitive areas.DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1338

  20. Changes in muscle size and MHC composition in response to resistance exercise with heavy and light loading intensity

    DEFF Research Database (Denmark)

    Holm, L.; Reitelseder, S.; Pedersen, T.G.

    2008-01-01

    resonance imaging, muscle biopsies were obtained bilaterally from vastus lateralis for determination of myosin heavy chain (MHC) composition, and maximal muscle strength was assessed by 1RM testing and in an isokinetic dynamometer at 60 degrees /s. Quadriceps muscle cross-sectional area increased (P ...Muscle mass accretion is accomplished by heavy-load resistance training. The effect of light-load resistance exercise has been far more sparsely investigated with regard to potential effect on muscle size and contractile strength. We applied a resistance exercise protocol in which the same...... individual trained one leg at 70% of one-repetition maximum (1RM) (heavy load, HL) while training the other leg at 15.5% 1RM (light load, LL). Eleven sedentary men (age 25 +/- 1 yr) trained for 12 wk at three times/week. Before and after the intervention muscle hypertrophy was determined by magnetic...

  1. Electrical resistivity of carbon black-filled high-density polyethylene (HDPE) composite containing radiation crosslinked HDPE particles

    International Nuclear Information System (INIS)

    Lee, M.-G.; Nho, Y.C.

    2001-01-01

    The room-temperature volume resistivity of high-density polyethylene (HDPE)-carbon black (CB) blends containing previously radiation crosslinked HDPE powder was studied. The results showed that the room-temperature volume resistivity decreases with increasing concentration of crosslinked HDPE powder. It is considered that the crosslinked HDPE particles act as a filler that increases the CB volume fraction in the HDPE matrix. The results of an optical microscope observation indicated that the crosslinked polymer particles are dispersed in the HDPE/CB composite. This effect of the crosslinked particles is attributed to the fact that the crosslinked mesh size of the HDPE particles is so small that the CB particles cannot go inside them. The effect of 60 Co γ-ray and electron beam (EB) irradiation on the positive temperature coefficient, negative temperature coefficient and electrical resistivity behavior of the blends were studied

  2. The electrical resistivity and percolation threshold of MWCNTs/polymer composites filled with a few aligned carbonyl iron particles

    Science.gov (United States)

    Dong, Shuai; Wang, Xiaojie

    2018-03-01

    Conductive polymer composites (CPCs) consist of multi-walled carbon nanotubes (MWCNTs), a few carbonyl iron particles (CIPs) and polydimethylsiloxane (PDMS) are fabricated under a moderate magnetic field. The alignment of CIPs will change the structure of MWCNT network, and consequently the electrical properties of CPCs. The volume fraction of CIPs is fixed at 0.08 vol% at which CIPs will not directly participate in electric conduction. The electrical resistivity of CPCs and the changes of resistance versus strain are evaluated at various MWCNT volume fractions. The testing results show that a percolation threshold as low as 0.19 vol% is obtained due to the effect of aligned CIPs, comparing with 0.39 vol% of isotropic MWCNT/CIP/PDMS (prepared without magnetic field). Meanwhile, the anisotropic structure reduces the electrical resistivity by more than 80% when the MWCNT volume fractions is over the percolation threshold.

  3. Nonequilibrium Alloying of Aluminum for Improving the Corrosion Resistance of Graphite-Reinforced Metal Matrix Composites

    National Research Council Canada - National Science Library

    Shaw, Barbara

    1994-01-01

    .... Unfortunately, MMCs, especially Gr reinforced composites, are extremely susceptible to corrosion with severe attack in chloride-containing environments occurring in as little time as several weeks for Gr/Al composites...

  4. Direct patterning of highly-conductive graphene@copper composites using copper naphthenate as a resist for graphene device applications.

    Science.gov (United States)

    Bi, Kaixi; Xiang, Quan; Chen, Yiqin; Shi, Huimin; Li, Zhiqin; Lin, Jun; Zhang, Yongzhe; Wan, Qiang; Zhang, Guanhua; Qin, Shiqiao; Zhang, Xueao; Duan, Huigao

    2017-11-09

    We report an electron-beam lithography process to directly fabricate graphene@copper composite patterns without involving metal deposition, lift-off and etching processes using copper naphthenate as a high-resolution negative-tone resist. As a commonly used industrial painting product, copper naphthenate is extremely cheap with a long shelf time but demonstrates an unexpected patterning resolution better than 10 nm. With appropriate annealing under a hydrogen atmosphere, the produced graphene@copper composite patterns show high conductivity of ∼400 S cm -1 . X-ray diffraction, conformal Raman spectroscopy and X-ray photoelectron spectroscopy were used to analyze the chemical composition of the final patterns. With the properties of high resolution and high conductivity, the patterned graphene@copper composites could be used as conductive pads and interconnects for graphene electronic devices with ohmic contacts. Compared to common fabrication processes involving metal evaporation and lift-off steps, this pattern-transfer-free fabrication process using copper naphthenate resist is direct and simple but allows comparable device performance in practical device applications.

  5. Improving the corrosion wear resistance of AISI 316L stainless steel by particulate reinforced Ni matrix composite alloying layer

    Science.gov (United States)

    Xu, Jiang; Zhuo, Chengzhi; Tao, Jie; Jiang, Shuyun; Liu, Linlin

    2009-01-01

    In order to overcome the problem of corrosion wear of AISI 316L stainless steel (SS), two kinds of composite alloying layers were prepared by a duplex treatment, consisting of Ni/nano-SiC and Ni/nano-SiO2 predeposited by brush plating, respectively, and subsequent surface alloying with Ni-Cr-Mo-Cu by a double glow process. The microstructure of the two kinds of nanoparticle reinforced Ni-based composite alloying layers was investigated by means of SEM and TEM. The electrochemical corrosion behaviour of composite alloying layers compared with the Ni-based alloying layer and 316L SS under different conditions was characterized by potentiodynamic polarization test and electrochemical impedance spectroscopy. Results showed that under alloying temperature (1000 °C) conditions, amorphous nano-SiO2 particles still retained the amorphous structure, whereas nano-SiC particles were decomposed and Ni, Cr reacted with SiC to form Cr6.5Ni2.5Si and Cr23C6. In static acidic solution, the corrosion resistance of the composite alloying layer with the brush plating Ni/nano-SiO2 particles interlayer is lower than that of the Ni-based alloying layer. However, the corrosion resistance of the composite alloying layer with the brush plating Ni/nano-SiO2 particles interlayer is prominently superior to that of the Ni-based alloying layer under acidic flow medium condition and acidic slurry flow condition. The corrosion resistance of the composite alloying layer with the brush plating Ni/nano-SiC particles interlayer is evidently lower than that of the Ni-based alloying layer, but higher than that of 316L SS under all test conditions. The results show that the highly dispersive nano-SiO2 particles are helpful in improving the corrosion wear resistance of the Ni-based alloying layer, whereas carbides and silicide phase are deleterious to that of the Ni-based alloying layer due to the fact that the preferential removal of the matrix around the precipitated phase takes place by the chemical

  6. The effect of pioglitazone and resistance training on body composition in older men and women undergoing hypocaloric weight loss.

    Science.gov (United States)

    Shea, M Kyla; Nicklas, Barbara J; Marsh, Anthony P; Houston, Denise K; Miller, Gary D; Isom, Scott; Miller, Michael E; Carr, J Jeffrey; Lyles, Mary F; Harris, Tamara B; Kritchevsky, Stephen B

    2011-08-01

    Age-related increases in ectopic fat accumulation are associated with greater risk for metabolic and cardiovascular diseases, and physical disability. Reducing skeletal muscle fat and preserving lean tissue are associated with improved physical function in older adults. PPARγ-agonist treatment decreases abdominal visceral adipose tissue (VAT) and resistance training preserves lean tissue, but their effect on ectopic fat depots in nondiabetic overweight adults is unclear. We examined the influence of pioglitazone and resistance training on body composition in older (65-79 years) nondiabetic overweight/obese men (n = 48, BMI = 32.3 ± 3.8 kg/m(2)) and women (n = 40, BMI = 33.3 ± 4.9 kg/m(2)) during weight loss. All participants underwent a 16-week hypocaloric weight-loss program and were randomized to receive pioglitazone (30 mg/day) or no pioglitazone with or without resistance training, following a 2 × 2 factorial design. Regional body composition was measured at baseline and follow-up using computed tomography (CT). Lean mass was measured using dual X-ray absorptiometry. Men lost 6.6% and women lost 6.5% of initial body mass. The percent of fat loss varied across individual compartments. Men who were given pioglitazone lost more visceral abdominal fat than men who were not given pioglitazone (-1,160 vs. -647 cm(3), P = 0.007). Women who were given pioglitazone lost less thigh subcutaneous fat (-104 vs. -298 cm(3), P = 0.002). Pioglitazone did not affect any other outcomes. Resistance training diminished thigh muscle loss in men and women (resistance training vs. no resistance training men: -43 vs. -88 cm(3), P = 0.005; women: -34 vs. -59 cm(3), P = 0.04). In overweight/obese older men undergoing weight loss, pioglitazone increased visceral fat loss and resistance training reduced skeletal muscle loss. Additional studies are needed to clarify the observed gender differences and evaluate how these changes in body composition influence functional status.

  7. Surface composition, microstructure and corrosion resistance of AZ31 magnesium alloy irradiated by high-intensity pulsed ion beam

    International Nuclear Information System (INIS)

    Li, P.; Lei, M.K.; Zhu, X.P.

    2011-01-01

    High-intensity pulsed ion beam (HIPIB) irradiation of AZ31 magnesium alloy is performed and electrochemical corrosion experiment of irradiated samples is carried out by using potentiodynamic polarization technology in order to explore the effect of HIPIB irradiation on corrosion resistance of magnesium alloy. The surface composition, cross-sectional morphology and microstructure are characterized by using electron probe microanalyzer, optical microscope and transmission electron microscope, respectively. The results indicated that HIPIB irradiation leads to a significant improvement in corrosion resistance of magnesium alloy, in terms of the considerable increase in both corrosion potential and pitting breakdown potential. The microstructural refinement and surface purification induced by HIPIB irradiation are responsible for the improved corrosion resistance. - Research Highlights: → A modified layer about 30 μm thick is obtained by HIPIB irradiation. → Selective ablation of element/impurity phase having lower melting point is observed. → More importantly, microstructural refinement occurred on the irradiated surface. → The modified layer exhibited a significantly improved corrosion resistance. → Improved corrosion resistance is ascribed to the combined effect induced by HIPIB.

  8. Fracture resistance of metal-free composite crowns-effects of fiber reinforcement, thermal cycling, and cementation technique.

    Science.gov (United States)

    Lehmann, Franziska; Eickemeyer, Grit; Rammelsberg, Peter

    2004-09-01

    The improved mechanical properties of contemporary composites have resulted in their extensive use for the restoration of posterior teeth. However, the influence of fiber reinforcement, cementation technique, and physical stress on the fracture resistance of metal-free crowns is unknown. This in vitro study evaluated the effect of fiber reinforcement, physical stress, and cementation methods on the fracture resistance of posterior metal-free Sinfony crowns. Ninety-six extracted human third molars received a standardized tooth preparation: 0.5-mm chamfer preparation and occlusal reduction of 1.3 to 1.5 mm. Sinfony (nonreinforced crowns, n=48) and Sinfony-Vectris (reinforced crowns, n=48) crowns restoring original tooth contour were prepared. Twenty-four specimens of each crown type were cemented, using either glass ionomer cement (GIC) or resin cement. Thirty-two crowns (one third) were stored in humidity for 48 hours. Another third was exposed to 10,000 thermal cycles (TC) between 5 degrees C and 55 degrees C. The remaining third was treated with thermal cycling and mechanical loading (TCML), consisting of 1.2 million axial loads of 50 N. The artificial crowns were then vertically loaded with a steel sphere until failure occurred. Significant differences in fracture resistance (N) between experimental groups were assessed by nonparametric Mann-Whitney U-test (alpha=.05). Fifty percent of the Sinfony and Sinfony-Vectris crowns cemented with glass ionomer cement loosened after thermal cycling. Thermal cycling resulted in a significant reduction in the mean fracture resistance for Sinfony crowns cemented with GIC, from 2037 N to 1282 N (P=.004). Additional fatigue produced no further effects. Fiber reinforcement significantly increased fracture resistance, from 1555 N to 2326 N (P=.001). The minimal fracture resistance was above 600 N for all combinations of material, cement and loading. Fracture resistance of metal-free Sinfony crowns was significantly increased by

  9. Effect of different composite core materials on fracture resistance of endodontically treated teeth restored with FRC posts

    Directory of Open Access Journals (Sweden)

    Prapaporn PANITIWAT

    Full Text Available Abstract Objective This study evaluated the fracture resistance of endodontically treated teeth restored with fiber reinforced composite posts, using three resin composite core build-up materials, (Clearfil Photo Core (CPC, MultiCore Flow (MCF, and LuxaCore Z-Dual (LCZ, and a nanohybrid composite, (Tetric N-Ceram (TNC. Material and Methods Forty endodontically treated lower first premolars were restored with quartz fiber posts (D.T. Light-Post cemented with resin cement (Panavia F2.0. Samples were randomly divided into four groups (n=10. Each group was built-up with one of the four core materials following its manufacturers’ instructions. The teeth were embedded in acrylic resin blocks. Nickel-Chromium crowns were fixed on the specimens with resin cement. The fracture resistance was determined using a universal testing machine with a crosshead speed of 1 mm/min at 1350 to the tooth axis until failure occurred. All core materials used in the study were subjected to test for the flexural modulus according to ISO 4049:2009. Results One-way ANOVA and Bonferroni multiple comparisons test indicated that the fracture resistance was higher in the groups with CPC and MCF, which presented no statistically significant difference (p>0.05, but was significantly higher than in those with LCZ and TNC (p<0.05. In terms of the flexural modulus, the ranking from the highest values of the materials was aligned with the same tendency of fracture loads. Conclusion Among the cores used in this study, the composite core with high filler content tended to enhance fracture thresholds of teeth restored with fiber posts more than others.

  10. Composites

    International Nuclear Information System (INIS)

    Kasen, M.B.

    1983-01-01

    This chapter discusses the roles of composite laminates and aggregates in cryogenic technology. Filamentary-reinforced composites are emphasized because they are the most widely used composite materials. Topics considered include composite systems and terminology, design and fabrication, composite failure, high-pressure reinforced plastic laminates, low-pressure reinforced plastics, reinforced metals, selectively reinforced structures, the effect of cryogenic temperatures, woven-fabric and random-mat composites, uniaxial fiber-reinforced composites, composite joints in cryogenic structures, joining techniques at room temperature, radiation effects, testing laminates at cryogenic temperatures, static and cyclic tensile testing, static and cyclic compression testing, interlaminar shear testing, secondary property tests, and concrete aggregates. It is suggested that cryogenic composite technology would benefit from the development of a fracture mechanics model for predicting the fitness-for-purpose of polymer-matrix composite structures

  11. SCIENTIFIC-METHODICAL PREREQUISITES FOR DEVELOPMENT OF THE STEEL COMPOSITIONS FOR INCREASE OF RESISTANCE OF HIGH-LOADED STAMPS OF COLD DEFORMATION

    Directory of Open Access Journals (Sweden)

    V. N. Fedulov

    2005-01-01

    Full Text Available The basis of perfecting of the known steels composition with the purpose of using for solving of concrete production problem, in particular increase of instrument resistance, are examined in the article.

  12. Wear Resistance Analysis of A359/SiC/20p Advanced Composite Joints Welded by Friction Stir Welding

    Directory of Open Access Journals (Sweden)

    O. Cuevas Mata

    Full Text Available Abstract Advancement in automotive part development demands new cost-effective materials with higher mechanical properties and improved wear resistance as compared to existing materials. For instance, Aluminum Matrix Composites (AMC shows improved mechanical properties as wear and abrasion resistance, high strength, chemical and dimensional stability. Automotive industry has focused in AMC for a variety of applications in automotive parts in order to improve the fuel economy, minimize vehicle emissions, improve design options, and increase the performance. Wear resistance is one of the most important factors in useful life of the automotive components, overall in those components submitted to mechanical systems like automotive brakes and suspensions. Friction Stir Welding (FSW rises as the most capable process to joining AMC, principally for the capacity to weld without compromising their ceramic reinforcement. The aim of this study is focused on the analysis of wear characteristics of the friction-stir welded joint of aluminum matrix reinforced with 20 percent in weight silicon carbide composite (A359/SiC/20p. The experimental procedure consisted in cut samples into small plates and perform three welds on these with a FSW machine using a tool with 20 mm shoulder diameter and 8 mm pin diameter. The wear features of the three welded joints and parent metal were analyzed at constant load applying 5 N and a rotational speed of 100 rpm employing a Pin-on - Disk wear testing apparatus, using a sapphire steel ball with 6 mm diameter. The experimental results indicate that the three welded joints had low friction coefficient compared with the parent metal. The results determine that the FSW process parameters affect the wear resistance of the welded joints owing to different microstructural modifications during welding that causes a low wear resistance on the welded zone.

  13. Oxidation-resistant interface coatings for SiC/SiC composites

    Energy Technology Data Exchange (ETDEWEB)

    Stinton, D.P.; Kupp, E.R.; Hurley, J.W.; Lowden, R.A. [Oak Ridge National Lab., TN (United States)] [and others

    1996-08-01

    The characteristics of the fiber-matrix interfaces in ceramic matrix composites control the mechanical behavior of these composites. Finite element modeling (FEM) was performed to examine the effect of interface coating modulus and coefficient of thermal expansion on composite behavior. Oxide interface coatings (mullite and alumina-titania) produced by a sol-gel method were chosen for study as a result of the FEM results. Amorphous silicon carbide deposited by chemical vapor deposition (CVD) is also being investigated for interface coatings in SiC-matrix composites. Processing routes for depositing coatings of these materials were developed. Composites with these interfaces were produced and tested in flexure both as-processed and after oxidation to examine the suitability of these materials as interface coatings for SiC/SiC composites in fossil energy applications.

  14. Surfactant-free electrodeposition of reduced graphene oxide/copper composite coatings with enhanced wear resistance

    Science.gov (United States)

    Mai, Y. J.; Zhou, M. P.; Ling, H. J.; Chen, F. X.; Lian, W. Q.; Jie, X. H.

    2018-03-01

    How to uniformly disperse graphene sheets into the electrolyte is one of the main challenges to synthesize graphene enhanced nanocomposites by electrodeposition. A surfactant-free colloidal solution comprised of copper (II)-ethylene diamine tetra acetic acid ([CuIIEDTA]2-) complexes and graphene oxide (GO) sheets is proposed to electrodeposit reduced graphene oxide/copper (RGO/Cu) composite coatings. Anionic [CuIIEDTA]2- complexes stably coexist with negatively charged GO sheets due to the electrostatic repulsion between them, facilitating the electrochemical reduction and uniform dispersion of GO sheets into the copper matrix. The RGO/Cu composite coatings are well characterized by XRD, Raman, SEM and XPS. Their tribological behavior as a function of RGO content in composite coatings and normal loads are investigated. Also the chemical composition and topography of the wear tracks for the composite coatings are analyzed to deduce the lubricating and anti-wear mechanism of RGO/Cu composite coatings.

  15. A novel Rapid Additive Manufacturing concept for architectural composite shell construction inspired by the shell formation in land snails.

    Science.gov (United States)

    Felbrich, Benjamin; Wulle, Frederik; Allgaier, Christoph; Menges, Achim; Verl, Alexander; Wurst, Karl-Heinz; Nebelsick, James

    2018-01-04

    State of the art rapid additive manufacturing (RAM), specifically Fused Filament Fabrication (FFF) has gained popularity among architects, engineers and designers for quick prototyping of technical devices, rapid production of small series and even construction scale fabrication of architectural elements. The spectrum of producible shapes and the resolution of detail, however, are determined and constrained by the layer-based nature of the fabrication process. These aspects significantly limit FFF-based approaches for the prefabrication and in-situ fabrication of freeform shells at the architectural scale. Snails exhibit a shell building process that suggests ways to overcome these limits. They produce a soft, pliable proteinaceous film - the periostracum - which later hardens and serves, among other functions, as a form-giving surface for an inner calcium carbonate layer. Snail shell formation behavior is interpreted from a technical point of view to extract potentially useful aspects for a biomimetic transfer. A RAM concept for continuous extrusion of thin free form composite shells inspired by the snail shell formation is presented. © 2018 IOP Publishing Ltd.

  16. Design and evaluation of low-cost laminated wood composite blades for intermediate size wind turbines: Blade design, fabrication concept, and cost analysis

    Science.gov (United States)

    Lieblein, S.; Gaugeon, M.; Thomas, G.; Zueck, M.

    1982-01-01

    As part of a program to reduce wind turbine costs, an evaluation was conducted of a laminated wood composite blade for the Mod-OA 200 kW wind turbine. The effort included the design and fabrication concept for the blade, together with cost and load analyses. The blade structure is composed of laminated Douglas fir veneers for the primary spar and nose sections, and honeycomb cored plywood panels for the trailing edges sections. The attachment of the wood blade to the rotor hub was through load takeoff studs bonded into the blade root. Tests were conducted on specimens of the key structural components to verify the feasibility of the concept. It is concluded that the proposed wood composite blade design and fabrication concept is suitable for Mod-OA size turbines (125-ft diameter rotor) at a cost that is very competitive with other methods of manufacture.

  17. The effect of morphology and surface composition on radiation resistance of heterogeneous material CdS-PbS

    Energy Technology Data Exchange (ETDEWEB)

    Malyar, I. V., E-mail: imalyar@yandex.ru; Stetsyura, S. V., E-mail: stetsyurasv@info.sgu.ru [Chernyshevsky Saratov State University (Russian Federation)

    2011-07-15

    As a result of a complex study of the heterophase photosensitive material CdS-PbS by the methods of scanning electron microscopy and Auger spectrometry, it has been found that the radiation resistance of this material depends on the morphology and phase composition at its surface. It is shown that, as the temperature of annealing is increased, aggregations with predominant content of PbS grow; simultaneously, the composition of these aggregations varies as a consequence of the reaction of substitution of sulfur atoms with oxygen atoms. The latter of the aforementioned processes brings about a decrease in the radiation resistance of the heterophase photosensitive material CdS-PbS, which is accounted for by a decrease in the gettering due to appearance of an intermediate oxidized layer between PbS and CdS. An increase in the sizes and number of spherical aggregations at the surface, which consist of crystallites with predominant content of PbS, brings about an increase in the radiation resistance.

  18. On the reception of the concept of the death drive in Germany: expressing and resisting an 'evil principle'?

    Science.gov (United States)

    Frank, Claudia

    2015-04-01

    With Beyond the Pleasure Principle, Freud attempted 'to describe and to account for the facts of daily observation in our field of study' (1920, p. 7), in particular concerning destructive clinical phenomena that confront us in the analytic situation: traumatic neuroses, melancholic states, negative-therapeutic reactions, masochism, repetition compulsion and so on. The author demonstrates in the first section how Freud's own resistance - later self-diagnosed - to recognizing these unwelcome facts was expressed in the terminological and conceptual ambiguities of the death drive hypothesis then introduced, ambiguities that to some extent continue to impede the reception of its clinical usefulness to this day. As soon as Freud had demonstrated the connection with clinical practice more directly in The Ego and the Id (1923), some contemporaries adopted it as a helpful clinical concept, while others believed that they could (and must) refute it. The second part outlines its reception in the 1920s and 1930s, which was part of an international discussion that was, of course, initially conducted mainly in German. The beginnings of an important further development of the death drive hypothesis are described in a separate section because it originated from Melanie Klein's earliest experiences in analysing children in Berlin in the early to mid-1920s. She referred at that time to an 'evil principle', and in 1932 published her view of the death drive hypothesis, which was further developed in subsequent decades by her and her followers in London. In this period, conditions changed dramatically: in Germany Freud's books (among others) were burnt, crimes against humanity were instigated and psychoanalysis ceased to exist in this country. Almost all the analysts who published on the death drive had to emigrate. From then on, entirely different discourses took place in the various regions. In Germany, the death drive hypothesis was (largely) disregarded or rejected for decades

  19. Effect of Si3N4 Addition on Oxidation Resistance of ZrB2-SiC Composites

    Directory of Open Access Journals (Sweden)

    Manab Mallik

    2017-06-01

    Full Text Available The oxidation behavior of ZrB2-20 vol % SiC and ZrB2-20 vol % SiC-5 vol % Si3N4 composites prepared by hot-pressing and subjected to isothermal exposure at 1200 or 1300 °C for durations of 24 or 100 h in air, as well as cyclic exposure at 1300 °C for 24 h, have been investigated. The oxidation resistance of the ZrB2-20 vol % SiC composite has been found to improve by around 20%–25% with addition of 5 vol % Si3N4 during isothermal or cyclic exposures at 1200 or 1300 °C. This improvement in oxidation resistance has been attributed to the formation of higher amounts of SiO2 and Si2N2O, as well as a greater amount of continuity in the oxide scale, because these phases assist in closing the pores and lower the severity of cracking by exhibiting self-healing type behavior. For both the composites, the mass changes are found to be higher during cyclic exposure at 1300 °C by about 2 times compared to that under isothermal conditions.

  20. Effects of resistance training and dietary changes on physical function and body composition in overweight and obese older adults.

    Science.gov (United States)

    Straight, Chad R; Dorfman, Leah R; Cottell, Kathryn E; Krol, Julie M; Lofgren, Ingrid E; Delmonico, Matthew J

    2012-08-01

    Community-based interventions that incorporate resistance training (RT) and dietary changes have not been extensively studied in overweight and obese older adults. The purpose of this investigation was to determine the effects of a community-based RT and dietary intervention on physical function and body composition in overweight and obese older adults. Ninety-five overweight and obese (BMI=33.4±4.0 kg/m2) older adults aged 55-80 years completed an 8-week RT and dietary intervention at 4 Rhode Island senior centers. Participants performed RT twice-weekly using resistance tubing, dumbbells, and ankle weights. Participants also attended 1 weekly dietary counseling session on a modified Dietary Approaches to Stop Hypertension diet. Outcome measurements included anthropometrics, body composition, and physical function. There were small changes in body mass (-1.0±1.8 kg, Pfoot up-and-go test time (-0.56±0.89 s, P<.001). Community-based RT and dietary modifications can improve body composition, muscle strength, and physical function in overweight and obese older adults. Future investigations should determine if this intervention is effective for long-term changes.

  1. Prevalence of antibiotic resistance genes and bacterial community composition in a river influenced by a wastewater treatment plant.

    Directory of Open Access Journals (Sweden)

    Elisabet Marti

    Full Text Available Antibiotic resistance represents a global health problem, requiring better understanding of the ecology of antibiotic resistance genes (ARGs, their selection and their spread in the environment. Antibiotics are constantly released to the environment through wastewater treatment plant (WWTP effluents. We investigated, therefore, the effect of these discharges on the prevalence of ARGs and bacterial community composition in biofilm and sediment samples of a receiving river. We used culture-independent approaches such as quantitative PCR to determine the prevalence of eleven ARGs and 16S rRNA gene-based pyrosequencing to examine the composition of bacterial communities. Concentration of antibiotics in WWTP influent and effluent were also determined. ARGs such as qnrS, bla TEM, bla CTX-M, bla SHV, erm(B, sul(I, sul(II, tet(O and tet(W were detected in all biofilm and sediment samples analyzed. Moreover, we observed a significant increase in the relative abundance of ARGs in biofilm samples collected downstream of the WWTP discharge. We also found significant differences with respect to community structure and composition between upstream and downstream samples. Therefore, our results indicate that WWTP discharges may contribute to the spread of ARGs into the environment and may also impact on the bacterial communities of the receiving river.

  2. Effect of impact energy on damage resistance and mechanical property of C/SiC composites under low velocity impact

    Energy Technology Data Exchange (ETDEWEB)

    Mei, Hui, E-mail: phdhuimei@yahoo.com; Yu, Changkui; Xu, Yawei; Han, Daoyang; Cheng, Laifei

    2017-02-27

    The present study investigated the damage resistance of two dimensional carbon fiber reinforced silicon carbide (C/SiCs) composites subjected to low velocity impact (LVI). Damage microstructures of specimens under different impact energies (E{sub i}) were characterized by infrared thermography, X-ray computed tomography and scanning electron microscopy. The real damage radii of specimens were found to change slightly with E{sub i}, whereas apparent damage radii where much larger. Overall, the fabricated 2D C/SiC composites exhibited good damage resistance to LVI with nominal post-impact tensile strengths remaining at 89.4%, 83.35%, 76.97%, and 74.84% of their pre-impacted counterpart of 158 MPa, for impact energies of 3, 4, 5, and 6 J, respectively. Compared with the as-received one, after LVI real tensile strengths of the C/SiC composite specimens increased by 5.84% for the E{sub i} of 3 J, 9.27% for 4 J, −1.83% for 5 J, −3.16% for 6 J.

  3. [Cellular composition of lymphoid nodules in the trachea wall in rats with different resistance to emotional stress in a model of hemorrhagic stroke].

    Science.gov (United States)

    Klyueva, L A

    2017-01-01

    To reveal regularities of changes in cellular composition of lymphoid nodules in the tracheal wall in male Wistar rats resistant and not resistant to emotional stress in a model of hemorrhagic stroke. Lymphoid formations of the tracheal wall (an area near the bifurcation of the organ) were investigated in 98 male Wistar rats using histological methods. Significant changes in the cellular composition of lymphoid nodules were found. The pattern of changes depends on the stress resistance of rats and the period of the experiment. The active cell destruction in lymphoid nodules was noted both in stress resistant and stress susceptible animals. The changes in the structure of lymphoid nodules found in the experimental hemorrhagic stroke suggest a decrease in the local immune resistance, which is most pronounced in rats not resistant to stress, that may contribute to the development of severe inflammatory complications of stroke such as pneumonia.

  4. Piezoelectric and mechanical properties of fatigue resistant, self-healing PZT-ionomer composites

    NARCIS (Netherlands)

    James, N.K.; Lafont, U.; Zwaag, S. van der; Groen, W.A.

    2014-01-01

    Piezoelectric ceramic-polymer composites with 0-3 connectivity were fabricated using lead zirconium titanate (PZT) powder dispersed in an ionomer (Zn ionomer) and its reference ethylene methacrylic acid copolymer (EMAA) polymer matrix. The PZT-Zn ionomer and PZT-EMAA composites were prepared by melt

  5. Development and optimization of manufacture process for heat resistant fibre reinforced ceramic matrix composites

    Czech Academy of Sciences Publication Activity Database

    Glogar, Petr; Hron, P.; Burian, M.; Balík, Karel; Černý, Martin; Sucharda, Zbyněk; Vymazalová, Z.; Červencl, J.; Pivoňka, M.

    -, č. 14 (2005), 25-32 ISSN 1214-9691 R&D Projects: GA ČR(CZ) GA106/02/0177 Institutional research plan: CEZ:AV0Z30460519 Keywords : polysiloxane resin * pyrolysis * ceramic matrix composite Subject RIV: JI - Composite Materials

  6. Characterization of Antibiotic Resistance Gene Abundance and Microbiota Composition in Feces of Organic and Conventional Pigs from Four EU Countries.

    Science.gov (United States)

    Gerzova, Lenka; Babak, Vladimir; Sedlar, Karel; Faldynova, Marcela; Videnska, Petra; Cejkova, Darina; Jensen, Annette Nygaard; Denis, Martine; Kerouanton, Annaelle; Ricci, Antonia; Cibin, Veronica; Österberg, Julia; Rychlik, Ivan

    2015-01-01

    One of the recent trends in animal production is the revival of interest in organic farming. The increased consumer interest in organic animal farming is mainly due to concerns about animal welfare and the use of antibiotics in conventional farming. On the other hand, providing animals with a more natural lifestyle implies their increased exposure to environmental sources of different microorganisms including pathogens. To address these concerns, we determined the abundance of antibiotic resistance and diversity within fecal microbiota in pigs kept under conventional and organic farming systems in Sweden, Denmark, France and Italy. The abundance of sul1, sul2, strA, tet(A), tet(B) and cat antibiotic resistance genes was determined in 468 samples by real-time PCR and the fecal microbiota diversity was characterized in 48 selected samples by pyrosequencing of V3/V4 regions of 16S rRNA. Contrary to our expectations, there were no extensive differences between the abundance of tested antibiotic resistance genes in microbiota originating from organic or conventionally housed pigs within individual countries. There were also no differences in the microbiota composition of organic and conventional pigs. The only significant difference was the difference in the abundance of antibiotic resistance genes in the samples from different countries. Fecal microbiota in the samples originating from southern European countries (Italy, France) exhibited significantly higher antibiotic resistance gene abundance than those from northern parts of Europe (Denmark, Sweden). Therefore, the geographical location of the herd influenced the antibiotic resistance in the fecal microbiota more than farm's status as organic or conventional.

  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

    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...... of steel fibre reinforced concrete (SFRC). The parameters investigated in the following are the fibre geometry, the fibre volume and the transitional resistance. On basis of the experimental results, a model, taking the resistivity of the fibres and the concrete matrix into account is proposed....... 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...

  8. Evaluation of contact resistance between carbon fiber/epoxy composite laminate and printed silver electrode for damage monitoring

    International Nuclear Information System (INIS)

    Jeon, Eun Beom; Kim, Hak Sung; Takahashi, Kosuke

    2014-01-01

    An addressable conducting network (ACN) makes it possible to monitor the condition of a structure using the electrical resistance between electrodes on the surface of a carbon fiber reinforced plastics (CFRP) structure. To improve the damage detection reliability of the ACN, the contact resistances between the electrodes and CFRP laminates needs to be minimized. In this study, silver nanoparticle electrodes were fabricated via printed electronics techniques on a CFRP composite. The contact resistance between the silver electrodes and CFRP were measured with respect to various fabrication conditions such as the sintering temperature of the silver nano-ink and the surface roughness of the CFRP laminates. The interfaces between the silver electrode and carbon fibers were observed using a scanning electron microscope (SEM). Based on this study, it was found that the lowest contact resistance of 0.3664Ω could be achieved when the sintering temperature of the silver nano-ink and surface roughness were 120 degree C and 0.230 a, respectively.

  9. Fabrication and characterization of a micromachined swirl-shaped ionic polymer metal composite actuator with electrodes exhibiting asymmetric resistance.

    Science.gov (United States)

    Feng, Guo-Hua; Liu, Kim-Min

    2014-05-12

    This paper presents a swirl-shaped microfeatured ionic polymer-metal composite (IPMC) actuator. A novel micromachining process was developed to fabricate an array of IPMC actuators on a glass substrate and to ensure that no shortcircuits occur between the electrodes of the actuator. We demonstrated a microfluidic scheme in which surface tension was used to construct swirl-shaped planar IPMC devices of microfeature size and investigated the flow velocity of Nafion solutions, which formed the backbone polymer of the actuator, within the microchannel. The unique fabrication process yielded top and bottom electrodes that exhibited asymmetric surface resistance. A tool for measuring surface resistance was developed and used to characterize the resistances of the electrodes for the fabricated IPMC device. The actuator, which featured asymmetric electrode resistance, caused a nonzero-bias current when the device was driven using a zero-bias square wave, and we propose a circuit model to describe this phenomenon. Moreover, we discovered and characterized a bending and rotating motion when the IPMC actuator was driven using a square wave. We observed a strain rate of 14.6% and a displacement of 700 μm in the direction perpendicular to the electrode surfaces during 4.5-V actuation.

  10. The Composition and Spatial Patterns of Bacterial Virulence Factors and Antibiotic Resistance Genes in 19 Wastewater Treatment Plants.

    Directory of Open Access Journals (Sweden)

    Bing Zhang

    Full Text Available Bacterial pathogenicity and antibiotic resistance are of concern for environmental safety and public health. Accumulating evidence suggests that wastewater treatment plants (WWTPs are as an important sink and source of pathogens and antibiotic resistance genes (ARGs. Virulence genes (encoding virulence factors are good indicators for bacterial pathogenic potentials. To achieve a comprehensive understanding of bacterial pathogenic potentials and antibiotic resistance in WWTPs, bacterial virulence genes and ARGs in 19 WWTPs covering a majority of latitudinal zones of China were surveyed by using GeoChip 4.2. A total of 1610 genes covering 13 virulence factors and 1903 genes belonging to 11 ARG families were detected respectively. The bacterial virulence genes exhibited significant spatial distribution patterns of a latitudinal biodiversity gradient and a distance-decay relationship across China. Moreover, virulence genes tended to coexist with ARGs as shown by their strongly positive associations. In addition, key environmental factors shaping the overall virulence gene structure were identified. This study profiles the occurrence, composition and distribution of virulence genes and ARGs in current WWTPs in China, and uncovers spatial patterns and important environmental variables shaping their structure, which may provide the basis for further studies of bacterial virulence factors and antibiotic resistance in WWTPs.

  11. Thermal Shock Resistance of Stabilized Zirconia/Metal Coat on Polymer Matrix Composites by Thermal Spraying Process

    Science.gov (United States)

    Zhu, Ling; Huang, Wenzhi; Cheng, Haifeng; Cao, Xueqiang

    2014-12-01

    Stabilized zirconia/metal coating systems were deposited on the polymer matrix composites by a combined thermal spray process. Effects of the thicknesses of metal layers and ceramic layer on thermal shock resistance of the coating systems were investigated. According to the results of thermal shock lifetime, the coating system consisting of 20 μm Zn and 125 μm 8YSZ exhibited the best thermal shock resistance. Based on microstructure evolution, failure modes and failure mechanism of the coating systems were proposed. The main failure modes were the formation of vertical cracks and delamination in the outlayer of substrate, and the appearance of coating spallation. The residual stress, thermal stress and oxidation of substrate near the substrate/metal layer interface were responsible for coating failure, while the oxidation of substrate near the substrate/coating interface was the dominant one.

  12. Effect of fed- versus fasted state resistance training during Ramadan on body composition and selected metabolic parameters in bodybuilders.

    Science.gov (United States)

    Trabelsi, Khaled; Stannard, Stephen R; Ghlissi, Zohra; Maughan, Ronald J; Kallel, Choumous; Jamoussi, Kamel; Zeghal, Khaled M; Hakim, Ahmed

    2013-04-25

    Muslim bodybuilders often continue training during Ramadan. However, the effect of resistance training in a fasted versus a fed state during Ramadan on body composition and metabolic parameters in bodybuilders is not well known. The aim of this study was to evaluate the effects of resistance training in a fasted versus a fed state during Ramadan on body composition and metabolic parameters in bodybuilders. Sixteen men were allocated to two groups: Eight practicing resistance training in the late afternoon in a fasted state (FAST), and eight training in the late evening in an acutely fed state (FED) during Ramadan. All visited the laboratory in the morning two days before the start of Ramadan (Bef-R) and on the 29th day of Ramadan (End-R) for anthropometric measurement, completion of a dietary questionnaire, and provision of fasting blood and urine samples. Body mass and body fat percentage remained unchanged in FAST and FED during the whole period of the investigation. Both FAST and FED experienced an increase in the following parameters from Bef-R to End-R: urine specific gravity (1%; p = 0.028, p = 0.004 respectively), serum concentrations of urea (4%, p = 0.006; 7%, p = 0.004 respectively), creatinine (5%, p = 0.015; 6%, p = 0.04 respectively), uric acid (17%; p Ramadan does not affect body mass and body composition of bodybuilders. Additionally, Ramadan fasting induced changes in urinary and some biochemical parameters, but these changes were not different according to when the training occurred.

  13. Composition

    DEFF Research Database (Denmark)

    Bergstrøm-Nielsen, Carl

    2011-01-01

    Strategies are open compositions to be realised by improvising musicians. See more about my composition practise in the entry "Composition - General Introduction". Caution: streaming the sound files will in some cases only provide a few minutes' sample. Please DOWNLOAD them to hear them in full...

  14. Composition

    DEFF Research Database (Denmark)

    2014-01-01

    Memory Pieces are open compositions to be realised solo by an improvising musicians. See more about my composition practise in the entry "Composition - General Introduction". Caution: streaming the sound files will in some cases only provide a few minutes' sample. Please DOWNLOAD them to hear them...

  15. Mechanisms of charge transport and resistive switching in composite films of semiconducting polymers with nanoparticles of graphene and graphene oxide

    Science.gov (United States)

    Berestennikov, A. S.; Aleshin, A. N.

    2017-11-01

    We have investigated the effect of the resistive switching in the composite films based on polyfunctional polymers - PVK, PFD and PVC mixed with particles of Gr and GO with the concentration of ˜ 1 - 3 wt.%. We have developed the solution processed hybrid memory structures based on PVK and GO particles composite films. The effect of the resistive switching in Al/PVK(PFD; PVC):Gr(GO)/ITO/PET structures manifests itself as a sharp change of the electrical resistance from a low-conducting state to a relatively high-conducting state when applying a bias to Al-ITO electrodes of ˜ 0.2-0.4 V. It has been established that a sharp conductivity jump characterized by S-shaped current-voltage curves and the presence of their hysteresis occurs upon applying a voltage pulse to the Au/PVK(PFD; PVC):Gr(GO)/ITO/PET structures, with the switching time in the range from 1 to 30 μs. The mechanism of resistive switching associated with the processes of capture and accumulation of charge carriers by Gr(GO) particles introduced into the matrixes of the PVK polymer due to the reduction/oxidation processes. The possible mechanisms of energy transfer between organic and inorganic components in PVK(PFD; PVC):GO(Gr) films causes increase mobility are discussed. Incorporating of Gr (GO) particles into the polymer matrix is a promising route to enhance the performance of hybrid memory structures, as well as it is an effective medium for memory cells.

  16. Insulin resistance, exercise capacity and body composition in subjects with two hypertensive parents

    DEFF Research Database (Denmark)

    Andersen, U B; Dige-Petersen, H; Ibsen, H

    1999-01-01

    -ray absorptiometry; (4) an exercise test with gas exchange analysis; and (5) investigation of composition of usual diet by diet registration for 5 days. RESULTS: The 24-h diastolic blood pressure was higher in subjects predisposed to hypertension compared with the controls: 78.1 versus 74.0 mmHg (confidence interval...... for the difference between the means; -0.5; -7.9), but the insulin sensitivity index was similar: 312 versus 362 I(2) min(-1) pmol(-1) kg(-1) (28; -129). The two groups were similar in terms of body composition, exercise capacity and composition of usual diet. Resting and 24-h diastolic blood pressures were...

  17. Oxidation-resistant interface coatings for Nicalon/SiC composites

    Energy Technology Data Exchange (ETDEWEB)

    Stinton, D.P.; Besmann, T.M.; Lowden, R.A. [Oak Ridge National Lab., TN (United States); Liaw, P.K.; Shanmugham, S. [Univ. of Tennessee, Knoxville, TN (United States)

    1997-12-01

    Nicalon/SiC composites with thin C and C/oxide/C interfaces were fabricated. The oxide layers, mullite and Al{sub 2}O{sub 3}-TiO{sub 2}, were deposited by a sol-gel process, while the C layer was deposited by a chemical vapor infiltration method. The fabricated composites were flexure tested in both as-processed and oxidized conditions. Composites with C and C/oxide/C interfaces retained graceful failure even after 500 h oxidation at 1000 C, but with reduced flexural strengths.

  18. Epoxy-borax-coal tar composition for a radiation protective, burn resistant drum liner and centrifugal casting method

    International Nuclear Information System (INIS)

    Boyer, N.W.; Taylor, R.S.

    1980-01-01

    A boron containing burn resistant, low level radiation protection material useful, for example, as a liner for radioactive waste disposal and storage, a component for neutron absorber, and a shield for a neutron source. The material is basically composed of borax in the range of 25-50%, coal tar in the range of 25-37.5%, with the remainder being an epoxy resin mix. A preferred composition is 50% borax, 25% coal tar and 25% epoxy resin. The material is not susceptible to burning and is about 1/5 the cost of existing radiation protection material utilized in similar applications

  19. High-performance flexible resistive memory devices based on Al2O3:GeOx composite

    Science.gov (United States)

    Behera, Bhagaban; Maity, Sarmistha; Katiyar, Ajit K.; Das, Samaresh

    2018-05-01

    In this study a resistive switching random access memory device using Al2O3:GeOx composite thin films on flexible substrate is presented. A bipolar switching characteristic was observed for the co-sputter deposited Al2O3:GeOx composite thin films. Al/Al2O3:GeOx/ITO/PET memory device shows excellent ON/OFF ratio (∼104) and endurance (>500 cycles). GeOx nanocrystals embedded in the Al2O3 matrix have been found to play a significant role in enhancing the switching characteristics by facilitating oxygen vacancy formation. Mechanical endurance was retained even after several bending. The conduction mechanism of the device was qualitatively discussed by considering Ohmic and SCLC conduction. This flexible device is a potential candidate for next-generation electronics device.

  20. Hexagonal Boron Nitride Impregnated Silane Composite Coating for Corrosion Resistance of Magnesium Alloys for Temporary Bioimplant Applications

    Directory of Open Access Journals (Sweden)

    Saad Al-Saadi

    2017-11-01

    Full Text Available Magnesium and its alloys are attractive potential materials for construction of biodegradable temporary implant devices. However, their rapid degradation in human body fluid before the desired service life is reached necessitate the application of suitable coatings. To this end, WZ21 magnesium alloy surface was modified by hexagonal boron nitride (hBN-impregnated silane coating. The coating was chemically characterised by Raman spectroscopy. Potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS of the coated alloy in Hanks’ solution showed a five-fold improvement in the corrosion resistance of the alloy due to the composite coating. Post-corrosion analyses corroborated the electrochemical data and provided a mechanistic insight of the improvement provided by the composite coating.

  1. Investigation on low room-temperature resistivity Cr/(Ba0.85Pb0.15)TiO3 positive temperature coefficient composites

    DEFF Research Database (Denmark)

    He, Zeming; Ma, J.; Qu, Yuanfang

    2009-01-01

    discussed. Using these special processes, the prepared composite with 20 wt% Cr possessed low room-temperature resistivity (2.96 Ω cm at 25 °C) and exhibited PTC effect (resistivity jump of 10), which is considered as a promising candidate for over-current protector when working at low voltage. The grain......Low room-temperature resistivity positive temperature coefficient (PTC) Cr/(Ba0.85Pb0.15)TiO3 composites were produced via a reducing sintering and a subsequent oxidation treatment. The effects of metallic content and processing conditions on materials resistivity–temperature properties were...

  2. Eight Weeks of Phosphatidic Acid Supplementation in Conjunction with Resistance Training Does Not Differentially Affect Body Composition and Muscle Strength in Resistance-Trained Men

    Directory of Open Access Journals (Sweden)

    Thomas L. Andre, Joshua J. Gann, Sarah K. McKinley-Barnard, Joon J. Song, Darryn S. Willoughby

    2016-09-01

    Full Text Available This study attempted to determine the effects of eight weeks of resistance training (RT combined with phosphatidic acid (PA supplementation at a dose of either 250 mg or 375 mg on body composition and muscle size and strength. Twenty-eight resistance-trained men were randomly assigned to ingest 375 mg [PA375 (n = 9] or 250 mg [PA250 (n = 9] of PA or 375 mg of placebo [PLC (n = 10] daily for eight weeks with RT. Supplements were ingested 60 minutes prior to RT and in the morning on non-RT days. Participants’ body composition, muscle size, and lower-body muscle strength were determined before and after training/supplementation. Separate group x time ANOVAs for each criterion variable were used employing an alpha level of ≤ 0.05. Magnitude- based inferences were utilized to determine the likely or unlikely impact of PA on each criterion variable. A significant main effect for time was observed for improvements in total body mass (p = 0.003, lean mass (p = 0.008, rectus femoris cross-sectional area [RF CSA (p = 0.011], and lower-body strength (p 0.05. Collectively, magnitude-based inferences determined both doses of PA to have a likely impact of increasing body mass (74.2%, lean mass (71.3%, RF CSA (92.2%, and very likely impact on increasing lower-body strength (98.1% beneficial. When combined with RT, it appears that PA has a more than likely impact on improving lower-body strength, whereas a likely impact exists for increasing muscle size and lean mass.

  3. Fracture Resistance of Endodontically Treated Teeth Restored with Biodentine, Resin Modified GIC and Hybrid Composite Resin as a Core Material.

    Science.gov (United States)

    Subash, Dayalan; Shoba, Krishnamma; Aman, Shibu; Bharkavi, Srinivasan Kumar Indu; Nimmi, Vijayan; Abhilash, Radhakrishnan

    2017-09-01

    The restoration of a severely damaged tooth usually needs a post and core as a part of treatment procedure to provide a corono - radicular stabilization. Biodentine is a class of dental material which possess high mechanical properties with excellent biocompatibility and bioactive behaviour. The sealing ability coupled with optimum physical properties could make Biodentine an excellent option as a core material. The aim of the study was to determine the fracture resistance of Biodentine as a core material in comparison with resin modified glass ionomer and composite resin. Freshly extracted 30 human permanent maxillary central incisors were selected. After endodontic treatment followed by post space preparation and luting of Glass fibre post (Reforpost, Angelus), the samples were divided in to three groups based on the type of core material. The core build-up used in Group I was Biodentine (Septodont, France), Group II was Resin-Modified Glass Ionomer Cement (GC, Japan) and Group III was Hybrid Composite Resin (TeEconom plus, Ivoclar vivadent). The specimens were subjected to fracture toughness using Universal testing machine (1474, Zwick/Roell, Germany) and results were compared using One-way analysis of variance with Tukey's Post hoc test. The results showed that there was significant difference between groups in terms of fracture load. Also, composite resin exhibited highest mean fracture load (1039.9 N), whereas teeth restored with Biodentine demonstrated the lowest mean fracture load (176.66 N). Resin modified glass ionomer exhibited intermediate fracture load (612.07 N). The primary mode of failure in Group I and Group II was favourable (100%) while unfavourable fracture was seen in Group III (30%). Biodentine, does not satisfy the requirements to be used as an ideal core material. The uses of RMGIC's as a core build-up material should be limited to non-stress bearing areas. Composite resin is still the best core build-up material owing to its high fracture

  4. Fracture resistance of endodontically treated teeth restored with Zirconia filler containing composite core material and fiber posts.

    Science.gov (United States)

    Jeaidi, Zaid Al

    2016-01-01

    To assess the fracture resistance of endodontically treated teeth with a novel Zirconia (Zr) nano-particle filler containing bulk fill resin composite. Forty-five freshly extracted maxillary central incisors were endodontically treated using conventional step back preparation and warm lateral condensation filling. Post space preparation was performed using drills compatible for fiber posts (Rely X Fiber Post) on all teeth (n=45), and posts were cemented using self etch resin cement (Rely X Unicem). Samples were equally divided into three groups (n=15) based on the type of core materials, ZirconCore (ZC) MulticCore Flow (MC) and Luxacore Dual (LC). All specimens were mounted in acrylic resin and loads were applied (Universal testing machine) at 130° to the long axis of teeth, at a crosshead speed of 0.5 mm/min until failure. The loads and the site at which the failures occurred were recorded. Data obtained was tabulated and analyzed using a statistical program. The means and standard deviations were compared using ANOVA and Multiple comparisons test. The lowest and highest failure loads were shown by groups LC (18.741±3.02) and MC (25.16±3.30) respectively. Group LC (18.741±3.02) showed significantly lower failure loads compared to groups ZC (23.02±4.21) and MC (25.16±3.30) (pcomposite cores was comparable to teeth restored with conventional Zr free bulk fill composites. Zr filled bulk fill composites are recommended for restoration of endodontically treated teeth as they show comparable fracture resistance to conventional composite materials with less catastrophic failures.

  5. Development of an oxidation resistant glass-ceramic composite coating on Ti-47Al-2Cr-2Nb alloy

    Science.gov (United States)

    Li, Wenbo; Zhu, Shenglong; Chen, Minghui; Wang, Cheng; Wang, Fuhui

    2014-02-01

    Three glass-ceramic composite coatings were prepared on Ti-47Al-2Cr-2Nb alloy by air spraying technique and subsequent firing. The aim of this work is to study the reactions between glass matrix and inclusions and their effects on the oxidation resistance of the glass-ceramic composite coating. The powders of alumina, quartz, or both were added into the aqueous solution of potassium silicate (ASPS) to form slurries used as the starting materials for the composite coatings. The coating formed from an ASPS-alumina slurry was porous, because the reaction between alumina and potassium silicate glass resulted in the formation of leucite (KAlSi2O6), consuming substantive glass phase and hindering the densification of the composite coating. Cracks were observed in the coating prepared from an ASPS-quartz slurry due to the larger volume shrinkage of the coating than that of the alloy. In contrast, an intact and dense SiO2-Al2O3-glass coating was successfully prepared from an ASPS-alumina-silica slurry. The oxidation behavior of the SiO2-Al2O3-glass composite coating on Ti-47Al-2Cr-2Nb alloy was studied at 900 °C. The SiO2-Al2O3-glass composite coating acted as an oxygen diffusion barrier, and prevented the inward diffusion of the oxygen from the air to the coating/alloy interface, therefore, decreasing the oxidation rate of the Ti-47Al-2Cr-2Nb alloy significantly.

  6. Accelerated Fatigue Resistance of Thick CAD/CAM Composite Resin Overlays Bonded with Light- and Dual-polymerizing Luting Resins.

    Science.gov (United States)

    Goldberg, Jack; Güth, Jan-Frederik; Magne, Pascal

    To evaluate the accelerated fatigue resistance of thick CAD/CAM composite resin overlays luted with three different bonding methods. Forty-five sound human second mandibular molars were organized and distributed into three experimental groups. All teeth were restored with a 5-mm-thick CAD/CAM composite resin overlay. Group A: immediate dentin sealing (IDS) with Optibond FL and luted with light-polymerizing composite (Herculite XRV). Group B: IDS with Optibond FL and luted with dual-polymerizing composite (Nexus 3). Group C: direct luting with Optibond FL and dual-polymerizing composite (Nexus 3). Masticatory forces at a frequency of 5 Hz were simulated using closed-loop servo-hydraulics and forces starting with a load of 200 N for 5000 cycles, followed by steps of 400, 600, 800, 1000, 1200 and 1400 N for a maximum of 30,000 cycles. Each step was applied through a flat steel cylinder at a 45-degree angle under submerged conditions. The fatigue test generated one failure in group A, three failures in group B, and no failures in group C. The survival table analysis for the fatigue test did not demonstrate any significant difference between the groups (p = 0.154). The specimens that survived the fatigue test were set up for the load-to-failure test with a limit of 4600 N. The survival table analysis for the load-to-failure test demonstrates an average failure load of 3495.20 N with survival of four specimens in group A, an average failure load of 4103.60 N with survival of six specimens in group B, and an average failure load of 4075.33 N with survival of nine specimens in group C. Pairwise comparisons revealed no significant differences (p composites in combination with IDS are not contraindicated with thick restorations.

  7. Toughened and corrosion- and wear-resistant composite structures and fabrication methods thereof

    Science.gov (United States)

    Seals, Roland D.; Ripley, Edward B.; Hallman, Russell L.

    2017-06-20

    Composite structures having a reinforced material interjoined with a substrate, wherein the reinforced material comprises a compound selected from the group consisting of titanium monoboride, titanium diboride, and combinations thereof.

  8. Multiply fully recyclable carbon fibre reinforced heat-resistant covalent thermosetting advanced composites.

    Science.gov (United States)

    Yuan, Yanchao; Sun, Yanxiao; Yan, Shijing; Zhao, Jianqing; Liu, Shumei; Zhang, Mingqiu; Zheng, Xiaoxing; Jia, Lei

    2017-03-02

    Nondestructive retrieval of expensive carbon fibres (CFs) from CF-reinforced thermosetting advanced composites widely applied in high-tech fields has remained inaccessible as the harsh conditions required to recycle high-performance resin matrices unavoidably damage the structure and properties of CFs. Degradable thermosetting resins with stable covalent structures offer a potential solution to this conflict. Here we design a new synthesis scheme and prepare a recyclable CF-reinforced poly(hexahydrotriazine) resin matrix advanced composite. The multiple recycling experiments and characterization data establish that this composite demonstrates performance comparable to those of its commercial counterparts, and more importantly, it realizes multiple intact recoveries of CFs and near-total recycling of the principal raw materials through gentle depolymerization in certain dilute acid solution. To our best knowledge, this study demonstrates for the first time a feasible and environment-friendly preparation-recycle-regeneration strategy for multiple CF-recycling from CF-reinforced advanced composites.

  9. Novel Nonporous Fouling-Resistant Enzymatic Composite Membranes for Waste Water Treatment

    National Research Council Canada - National Science Library

    Freeman, Benny D

    2005-01-01

    .... Permeation properties of thin-films made of these gels is also reported. Approximately 20 m2 of chitosan composite membrane were prepared at our industrial partner, Membrane Technology and Research (MTR...

  10. [The effect of N-stearoylethanolamine on liver phospholipid composition of rats with insulin resistance caused by alimentary obesity].

    Science.gov (United States)

    Onopchenko, O V; Kosiakova, H V; Horid'ko, T M; Klimashevskyĭ, V M; Hula, N M

    2014-01-01

    We used alimentary obesity-induced insulin resistance (IR) model in rats to investigate the influence of N-stearoylethanolamine on the content of phospholipids and their fatty acid composition. Our results show that prolonged high-fat diet triggers considerable aberrations in the composition of main phospholipids in the liver and can be one of the causes of IR in rats. In particular, the increase of phosphatidylcholine, phosphatidylethanolamine and significant decrease of other phospholipids: lysophosphatidylcholine, lysophosphatidylethanolamine, sphingomyelin, phosphatidylinositol, phosphatidylserine and diphosphaglicerol were observed. The levels of monounsaturated (erucic, nervonic, oleic) and polyunsaturated (eicosatrienoic, docosatrienoic, arachidonic) fatty acids were increased; meanwhile the content of diunsaturated acids was decreased. The NSE administration (50 mg/kg of body weight) caused restoration of the phospholipids content in the liver of rats with diet-induced IR that highly correlated with the decrease in plasma insulin level and the improvement of insulin sensitivity. Moreover, the effect of NSE was accompanied by the normalization of fatty acids composition of phospholipids that could be related to modulating influence of NSE on the activity of the main fatty acid desaturases. It is known that the imbalance in phospholipid composition of the rat liver causes substantial metabolic alterations that are associated with the development of IR. Accordingly, the compensations of the imbalance by NSE can help to restore insulin sensitivity, inhibit the development of obesity, IR and type 2 diabetes.

  11. Compressive fracture resistance of the marginal ridge in large Class II tunnels restored with cermet and composite resin.

    Science.gov (United States)

    Ehrnford, L E; Fransson, H

    1994-01-01

    Compressive fracture resistance of the marginal ridge was studied in large tunnel preparations, before and after restoration with cermet (Ketac Silver, ESPE), a universal hybrid composite (Superlux, DMG) and an experimental composite. Each group was represented by six tunnels in extracted upper premolars. The tunnels were prepared by the use of round burs up to size #6. Remaining ridge width was 1.5 mm and ridge height 1.7 mm in the contact area. The ridge was loaded to fracture by a rod placed perpendicular to the ridge. Generally this resulted in a shear fracture of the restoration. There was no significant reinforcement of the ridge by the cermet whereas the composites both reinforced by the same magnitude, averaging 62%. It was concluded that the ridge could be considered a "megafiller" where contact need to be preserved and contour protected against proximal and occlusal wear of the restoration. Clinically there would therefore be good reasons to save even ridge areas with very low inherent strength. Based on the present study composite resin might therefore be the filling material of choice for such tunnel preparations.

  12. Preparation and Wear Resistance of Aluminum Composites Reinforced with In Situ Formed TiO/Al2O3

    Science.gov (United States)

    Qin, Q. D.; Huang, B. W.; Li, W.; Zeng, Z. Y.

    2016-05-01

    An in situ TiO/Al2O3-reinforced Al composite is successfully prepared using a powder metallurgy route by the reaction of Ti2CO and Al powder. The Ti2CO powder is produced by carrying out a carbothermic reduction of titanium dioxide at 1000 °C. XRD results show that the final product is composed of Al, TiO, Al2O3, and Al3Ti. Morphology examination of the composite reveals the presence of bigger blocks of TiO and fine particles of Al2O3 and the volume fraction of reinforcement is found to range between 18 and 55%. As the volume fraction of the reinforced materials approaches 50%, the particles start to agglomerate. Dry sliding wear tests conducted using a conventional pin-on-disk testing machine show that the wear resistance of the composite is higher than that of the pure aluminum ingot. The wear rate of the composite increases almost linearly with the increase in the wear distance. The sliding wear test shows that as the volume fraction of the reinforced phase increases, the coefficient of friction decreases. The wear mechanism is also discussed.

  13. The effect of N-stearoylethanolamine on liver phospholipid composition of rats with insulin resistance caused by alimentary obesity

    Directory of Open Access Journals (Sweden)

    O. V. Onopchenko

    2014-02-01

    Full Text Available We used alimentary obesity-induced insulin resistance (IR model in rats to investigate the influence of N-stearoylethanolamine on the content of phospholipids and their fatty acid composition. Our results show that prolonged high-fat diet triggers considerable aberrations in the composition of main phospholipids in the liver and can be one of the causes of IR in rats. In particular, the increase of phosphatidylcholine, phosphatidylethanolamine and significant decrease of other phospholipids: lysophosphatidylcholine, lysophosphatidylethanolamine, sphingomyelin, phosphatidylinositol, phosphatidylserine and diphosphaglicerol were observed. The levels of monounsaturated (erucic, nervonic, oleic and polyunsaturated (eicosatrienoic, docosatrienoic, arachidonic fatty acids were increased; meanwhile the content of diunsaturated acids was decreased. The NSE administration (50 mg/kg of body weight caused restoration of the phospholipids content in the liver of rats with diet-induced IR that highly correlated with the decrease in plasma insulin level and the improvement of insulin sensitivity. Moreover, the effect of NSE was accompanied by the normalization of fatty acids composition of phospholipids that could be related to modulating influen­ce of NSE on the activity of the main fatty acid desaturases. It is known that the imbalance in phospholipid composition of the rat liver causes substantial metabolic alterations that are associated with the development of IR. Accordingly, the compensations of the imbalance by NSE can help to restore insulin sensitivity, inhibit the development of obesity, IR and type 2 diabetes.

  14. Evaluation of Blast Resistance of Fiber Reinforced Composite Specimens under Contact Blast Load

    Science.gov (United States)

    Janota, O.; Foglar, M.

    2017-09-01

    This paper presents results of experimental programme which took place in 2014, 2015 and 2016. Experiments were focused on the resistance of full scale concrete panels subjected to contact blast loading. Specimens were loaded by contact blast by plastic explosive. All specimens were reinforced concrete slabs made of fiber concrete. Basalt mesh and textile sheets were added to some of the experiments for creating more heterogeneous material to achieve better resistance of the specimens. Evaluation of experiments was mainly focused on the damaged area on the contact side and soffit of the specimens. Dependency of the final damage of concrete panels on the weight of explosive and concrete strength was assessed.

  15. Using Expectancy Value Theory as a Framework to Reduce Student Resistance to Active Learning: A Proof of Concept

    OpenAIRE

    Cooper, Katelyn M.; Ashley, Michael; Brownell, Sara E.

    2017-01-01

    There has been a national movement to transition college science courses from passive lectures to active learning environments. Active learning has been shown to be a more effective way for students to learn, yet there is concern that some students are resistant to active learning approaches. Although there is much discussion about student resistance to active learning, few studies have explored this topic. Furthermore, a limited number of studies have applied theoretical frameworks to studen...

  16. In vitro fracture resistance of molar teeth restored with a short fibre-reinforced composite material.

    Science.gov (United States)

    Fráter, Márk; Forster, András; Keresztúri, Márk; Braunitzer, Gábor; Nagy, Katalin

    2014-09-01

    The purpose of this in vitro study was to evaluate the efficiency of a short fibre-reinforced composite (SFRC) material compared to conventional composites when restoring class II. MOD cavities in molar teeth with different layering techniques. One hundred and thirty mandibular third molars were divided into 5 groups (n=26). Except for the control group (intact teeth), in all other groups MOD cavities were prepared. The cavities were restored by either conventional composite with horizontal and oblique layering or by SFRC with horizontal and oblique layering. The specimens were submitted to static fracture toughness test. Fracture thresholds and fracture patterns were evaluated. In general, no statistically significant difference was found in fracture toughness between the study groups, except for horizontally layered conventional composite restorations, which turned out to be significantly weaker than controls. However, SFRC yielded noticeably higher fracture thresholds and only obliquely applied SFRC restorations exhibited favourable fracture patterns above chance level. The application of SFRC did not lead to a statistically significant improvement of the fracture toughness of molar teeth with MOD cavities. Still, SFRC applied in oblique increments measurably reduces the chance of unrestorable fractures of molar teeth with class II MOD cavities. The restoration of severely weakened molar teeth with the use of SFRC combined with composite might have advantages over conventional composites alone. It was observed from the statistical data, that the application of SFRC with an oblique layering technique yielded not significantly but better fracture thresholds and more favourable fracture patterns than any other studied material/technique combination. Thus further investigations need to be carried out, to investigate the possible positive mechanical effects of SFRC. The application of the horizontal layering technique with conventional composite materials is inferior

  17. Corrosion resistance of Zn-Al layered double hydroxide/poly(lactic acid) composite coating on magnesium alloy AZ31

    Science.gov (United States)

    Zeng, Rong-Chang; Li, Xiao-Ting; Liu, Zhen-Guo; Zhang, Fen; Li, Shuo-Qi; Cui, Hong-Zhi

    2015-12-01

    A Zn-Al layered double hydroxide (ZnAl-LDH) coating consisted of uniform hexagonal nano-plates was firstly synthesized by co-precipitation and hydrothermal treatment on the AZ31 alloy, and then a poly(lactic acid) (PLA) coating was sealed on the top layer of the ZnAl-LDH coating using vacuum freeze-drying. The characteristics of the ZnAl-LDH/PLA composite coatings were investigated by means of XRD, SEM, FTIR and EDS. The corrosion resistance of the coatings was assessed by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that the ZnAl-LDH coating contained a compact inner layer and a porous outer layer, and the PLA coating with a strong adhesion to the porous outer layer can prolong the service life of the ZnAl-LDH coating. The excellent corrosion resistance of this composite coating can be attributable to its barrier function, ion-exchange and self-healing ability.

  18. The Variations of Thermal Contact Resistance and Heat Transfer Rate of the AlN Film Compositing with PCM

    Directory of Open Access Journals (Sweden)

    Huann-Ming Chou

    2015-01-01

    Full Text Available The electrical industries have been fast developing over the past decades. Moreover, the trend of microelements and packed division multiplex is obviously for the electrical industry. Hence, the high heat dissipative and the electrical insulating device have been popular and necessary. The thermal conduct coefficient of aluminum nitride (i.e., AlN is many times larger than the other materials. Moreover, the green technology of composite with phase change materials (i.e., PCMs is worked as a constant temperature cooler. Therefore, PCMs have been used frequently for saving energy and the green environment. Based on the above statements, it does show great potential in heat dissipative for the AlN film compositing with PCM. Therefore, this paper is focused on the research of thermal contact resistance and heat transfer between the AlN/PCM pairs. According to the experimental results, the heat transfer decreases and the thermal contact resistance increases under the melting process of PCM. However, the suitable parameters such as contact pressures can be used to improve the above defects.

  19. Influence of high sintering pressure on the microhardness and wear resistance of diamond powder and silicon carbide-based composites

    Directory of Open Access Journals (Sweden)

    Osipov Oleksandr Sergueevitch

    2004-01-01

    Full Text Available The work reported on here involved the development of several samples of "diamond-SiC" composite produced under sintering pressures of up to 9.0 GPa at temperatures of up to 1973 7K. The average size of the diamond micropowder crystals used was 40/28 µm. The sintering process was carried out in a 2500-ton hydraulic press equipped with an anvil-type high-pressure device having a toroidal work surface and a central concavity diameter of 20 mm. The microhardness and wear resistance of the samples were found to be dependent on the sintering pressure. The experimental results indicated that the maximum microhardness and minimum wear resistance coefficients of each compact were attained when the pressure applied during sintering exceeded 6.5 GPa. Based on the established values of pressure, this study served to identify the types of devices applicable for the manufacture of composite material inserts for a variety of rock drilling applications.

  20. Experimental investigation of copper matrix longitudinal resistance in a composite Nb-Ti wire

    International Nuclear Information System (INIS)

    Gubkin, I.N.; Kozlenkova, N.I.; Nikulin, A.D.; Polikarpova, M.V.; Filkin, V.Ya.

    1994-01-01

    The longitudinal resistance of multifilamentary superconducting wires is among the major parameters used in design and optimization of superconducting magnetic systems. To enhance the conductivity of the copper matrix, it is made of pipes and rods of enhanced quality copper produced by electron beam melting (resistance ratio between two temperatures, 295 K and 4.2 K, R 295 /R 4.2 > 200). Yet for readily obtainable conductors this parameter is much lower. The reduction of the copper-matrix electrical conductivity may be attributed to wire-production technology involving processes such as extrusion, drawing and intermediate thermal processing, as well as to the size effect. Copper-matrix longitudinal resistance was studied as a function of wire diameter on specimens of multifilamentary Nb-Ti wire with filaments coated by a Nb layer. Experimental results are compared with the Sondheimer calculations for a monofilament conductor as well as with the Gavalloni calculations for an ideal wire with hexagonally located filaments. It has been shown that the best fit with the experiment is provided by the Sondheimer approximation. Comparison of the results of this work with other authors' data obtained for the specimens with no niobium barrier, allows the authors to single out the influence of a pure size effect and diffusion of Ti on the resistivity

  1. Multilayer sulfur-resistant composite metal membranes and methods of making and repairing the same

    Science.gov (United States)

    Way, J. Douglas; Hatlevik, Oyvind

    2014-07-15

    The invention relates to thin, hydrogen-permeable, sulfur-resistant membranes formed from multi-layers of palladium or palladium-alloy coatings on porous, ceramic or metal supports, methods of making these membranes, methods of repairing layers of these membranes and devices that incorporate these membranes.

  2. Diversity and community composition of tributyltin-resistant bacteria under different conditions

    International Nuclear Information System (INIS)

    Lee, Y. H.; Park, S.; Park, H.; Choi, Y

    2009-01-01

    Tributyltin (TBT) is an organometallic compound used as anti fouling agent in marine paints. this compound is toxic not only for eukaryotes, but also for bacteria. Based on the literature review, a few researchers have reported evidence for the presence of TBT-resistant bacteria in natural seawater and marine sediment. (Author)

  3. Diversity and community composition of tributyltin-resistant bacteria under different conditions

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Y. H.; Park, S.; Park, H.; Choi, Y

    2009-07-01

    Tributyltin (TBT) is an organometallic compound used as anti fouling agent in marine paints. this compound is toxic not only for eukaryotes, but also for bacteria. Based on the literature review, a few researchers have reported evidence for the presence of TBT-resistant bacteria in natural seawater and marine sediment. (Author)

  4. Carbon and nitrogen molecular composition of soil organic matter fractions resistant to oxidation

    Science.gov (United States)

    Katherine Heckman; Dorisel Torres; Christopher Swanston; Johannes Lehmann

    2017-01-01

    The methods used to isolate and characterise pyrogenic organic carbon (PyC) from soils vary widely, and there is little agreement in the literature as to which method truly isolates the most chemically recalcitrant (inferred from oxidative resistance) and persistent (inferred from radiocarbon abundance) fraction of soil organic matter. In addition, the roles of fire,...

  5. Neuroendocrine Responses and Body Composition Changes Following Resistance Training Under Normobaric Hypoxia

    Directory of Open Access Journals (Sweden)

    Chycki Jakub

    2016-12-01

    Full Text Available The aim of the present study was to evaluate the effects of a 6 week resistance training protocol under hypoxic conditions (FiO2 = 12.9%, 4000 m on muscle hypertrophy. The project included 12 resistance trained male subjects, randomly divided into two experimental groups. Group 1 (n = 6; age 21 ± 2.4 years; body height [BH] 178.8 ± 7.3 cm; body mass [BM] 80.6 ± 12.3 kg and group 2 (n = 6; age 22 ± 1.5 years; BH 177.8 ± 3.7cm; BM 81.1 ± 7.5 kg. Each group performed resistance exercises alternately under normoxic and hypoxic conditions (4000 m for 6 weeks. All subjects followed a training protocol that comprised two training sessions per week at an exercise intensity of 70% of 1RM; each training session consisted of eight sets of 10 repetitions of the bench press and barbell squat, with 3 min rest periods. The results indicated that strength training in normobaric hypoxia caused a significant increase in BM (p < 0.01 and fat free mass (FFM (p < 0.05 in both groups. Additionally, a significant increase (p < 0.05 was observed in IGF-1 concentrations at rest after 6 weeks of hypoxic resistance training in both groups. The results of this study allow to conclude that resistance training (6 weeks under normobaric hypoxic conditions induces greater muscle hypertrophy compared to training in normoxic conditions.

  6. Protein adsorption resistant surface on polymer composite based on 2D- and 3D-controlled grafting of phospholipid moieties

    International Nuclear Information System (INIS)

    Hoshi, Toru; Matsuno, Ryosuke; Sawaguchi, Takashi; Konno, Tomohiro; Takai, Madoka; Ishihara, Kazuhiko

    2008-01-01

    To prepare the biocompatible surface, a phosphorylcholine (PC) group was introduced on this hydroxyl group generated by surface hydrolysis on the polymer composite composed of polyethylene (PE) and poly (vinyl acetate) (PVAc) prepared by supercritical carbon dioxide. Two different procedures such as two-dimensional (2D) modification and three-dimensional (3D) modification were applied to obtain the steady biocompatible surface. 2D modification was that PC groups were directly anchored on the surface of the polymer composite. 3D modification was that phospholipid polymer was grafted from the surface of the polymer composite by surface-initiated atom transfer radical polymerization (SI-ATRP) of 2-methacryloyloxyethyl phosphorylcholine (MPC). The surfaces were characterized by X-ray photoelectron spectroscopy, dynamic water contact angle measurements, and atomic force microscope. The effects of the poly(MPC) chain length on the protein adsorption resistivity were investigated. The protein adsorption on the polymer composite surface with PC groups modified by 2D or 3D modification was significantly reduced as compared with that on the unmodified PE. Further, the amount of protein adsorbed on the 3D modified surface that is poly(MPC)-grafted surface decreased with an increase in the chain length of the poly(MPC). The surface with an arbitrary structure and the characteristic can be constructed by using 2D and 3D modification. We conclude that the polymer composites of PE/PVAc with PC groups on the surface are useful for fabricating biomedical devices due to their good mechanical and surface properties

  7. Compositions of corrosion-resistant Fe-based amorphous metals suitable for producing thermal spray coatings

    Science.gov (United States)

    Farmer, Joseph C; Wong, Frank M.G.; Haslam, Jeffery J; Ji, Xiaoyan; Day, Sumner D; Blue, Craig A; Rivard, John D.K.; Aprigliano, Louis F; Kohler, Leslie K; Bayles, Robert; Lemieux, Edward J; Yang, Nancy; Perepezko, John H; Kaufman, Larry; Heuer, Arthur; Lavernia, Enrique J

    2013-09-03

    A method of coating a surface comprising providing a source of amorphous metal that contains manganese (1 to 3 atomic %), yttrium (0.1 to 10 atomic %), and silicon (0.3 to 3.1 atomic %) in the range of composition given in parentheses; and that contains the following elements in the specified range of composition given in parentheses: chromium (15 to 20 atomic %), molybdenum (2 to 15 atomic %), tungsten (1 to 3 atomic %), boron (5 to 16 atomic %), carbon (3 to 16 atomic %), and the balance iron; and applying said amorphous metal to the surface by a spray.

  8. Testing of Composite Fan Vanes With Erosion-Resistant Coating Accelerated

    Science.gov (United States)

    Bowman, Cheryl L.; Sutter, James K.; Otten, Kim D.; Samorezov, Sergey; Perusek, Gail P.

    2004-01-01

    The high-cycle fatigue of composite stator vanes provided an accelerated life-state prior to insertion in a test stand engine. The accelerated testing was performed in the Structural Dynamics Laboratory at the NASA Glenn Research Center under the guidance of Structural Mechanics and Dynamics Branch personnel. Previous research on fixturing and test procedures developed at Glenn determined that engine vibratory conditions could be simulated for polymer matrix composite vanes by using the excitation of a combined slip table and electrodynamic shaker in Glenn's Structural Dynamics Laboratory. Bench-top testing gave researchers the confidence to test the coated vanes in a full-scale engine test.

  9. Chemical composition and modulation of bacterial drug resistance of the essential oil from leaves of Croton grewioides.

    Science.gov (United States)

    de Medeiros, Vivianne Marcelino; do Nascimento, Yuri Mangueira; Souto, Augusto Lopes; Madeiro, Sara Alves Lucena; Costa, Vicente Carlos de Oliveira; Silva, Suellen Maria P M; Falcão Silva, Vivyanne Dos Santos; Agra, Maria de Fátima; de Siqueira-Júnior, José Pinto; Tavares, Josean Fechine

    2017-10-01

    The essential oil from leaves of Croton grewioides Baill was obtained by hydrodistillation using Clevenger apparatus, and its chemical composition was analyzed by GC-MS, where 18 compounds were identified, mostly as monoterpenes (55.56%) and sesquiterpenes (44.44%), in which the major constituent was the α-pinene (47.43%). The essential oil of Croton grewioides (EOCg) and its major compound (α-pinene) were evaluated as modulators of antibiotic resistance in strain SA-1199B and IS-58 of Staphylococcus aureus that overexpresses efflux protein. The minimum inhibitory concentrations (MICs) of the antibiotics were determined by the microdilution assay in the absence and in the presence of sub-inhibitory concentration of EOCg and α-pinene. Although the EOCg and α-pinene did not indicate relevant antibacterial activity in vitro, they acted as antibiotic resistance modulators, i.e., EOCg in combination with norfloxacin, reducted its MIC, by 64× whereas in combination with tetracycline it was observed a reduction of 4×. Additionally, it was observed a MIC reduction of tetracycline by 32×, when combined with α-pinene. The results suggest that EOCg and α-pinene modulate or even reverse bacterial resistance as a putative efflux pump inhibitor. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. The fabrication, nano/micro-structure, heat- and wear-resistance of the superhydrophobic PPS/PTFE composite coatings.

    Science.gov (United States)

    Wang, Huaiyuan; Zhao, Jingyan; Zhu, Youzhuang; Meng, Yang; Zhu, Yanji

    2013-07-15

    A simple engineering method was used to fabricate stability and wear-resistance of superhydrophobic PPS-based PPS/PTFE surfaces through nano/micro-structure design and modification of the lowest surface energy groups (-CF2-), which was inspired by the biomimic lotus leaves. The hydrophobic properties and wear-resistance of the coatings were measured by a contact angle meter and evaluated on a pin-on-disk friction and wear tester, respectively. Moreover, the surfaces of the PPS/PTFE composite coatings were investigated by means of scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), and thermogravimetry (TG) analysis. Results showed that the highest contact angle of the PPS/PTFE surface, with papillae-like randomly distributed double-scale structure, could reach up to 162°. When 1 wt.% PDMS was added, the highest contact angle could hold is 172°. The coatings also retained superhydrophobicity, even under high temperature environment. The investigation also indicated that the coatings were not only superhydrophobic but also oleophobic behavior at room temperature, such as the crude oil, glycerol, and oil-water mixture. The PPS/45%PTFE coatings had more stable friction coefficient and excellent wear-resistance (331,407 cycles) compared with those with less than 45% of PTFE. Copyright © 2012 Elsevier Inc. All rights reserved.

  11. Formation of structure, phase composition and properties of electro explosion resistant coatings using electron-beam processing

    International Nuclear Information System (INIS)

    Romanov, Denis A.; Sosnin, Kirill V.; Budovskikh, Evgenij A.; Gromov, Viktor E.; Semin, Alexander P.

    2014-01-01

    For the first time, the high intensity electron beam modification of electroexplosion composite coatings of MoCu, MoCCu, WCu, WCCu and TiB 2 Cu systems was done. The studies of phase and elemental composition, defective structure conditions of these coatings were carried out. The regimes of electron-beam processing making possible to form the dense, specular luster surface layers having a submicrocrystalline structure were revealed. It was established that electron-beam processing of elecroexplosion spraying of layer of elecroexplosion spraying carried out in the regime of melting results in the formation of structurally and contrationally homogeneous surface layer. Investigation of the effect of electron-beam processing of electroexplosion electroerosion resistant coatings on their tribological properties (wear resistanse and coefficient of friction) and electroerosion resistance was done. It was shown that all the examined costings demonstrate the increase of electroerosion resistance in spark erosion up to 10 times

  12. Formation of structure, phase composition and properties of electro explosion resistant coatings using electron-beam processing

    Energy Technology Data Exchange (ETDEWEB)

    Romanov, Denis A., E-mail: romanov-da@physics.sibsiu.ru, E-mail: kos2906@mail.ru, E-mail: budovskih-ea@physics.sibsiu.ru, E-mail: gromov@physics.sibsiu.ru, E-mail: da-rom@live.ru; Sosnin, Kirill V., E-mail: romanov-da@physics.sibsiu.ru, E-mail: kos2906@mail.ru, E-mail: budovskih-ea@physics.sibsiu.ru, E-mail: gromov@physics.sibsiu.ru, E-mail: da-rom@live.ru; Budovskikh, Evgenij A., E-mail: romanov-da@physics.sibsiu.ru, E-mail: kos2906@mail.ru, E-mail: budovskih-ea@physics.sibsiu.ru, E-mail: gromov@physics.sibsiu.ru, E-mail: da-rom@live.ru; Gromov, Viktor E., E-mail: romanov-da@physics.sibsiu.ru, E-mail: kos2906@mail.ru, E-mail: budovskih-ea@physics.sibsiu.ru, E-mail: gromov@physics.sibsiu.ru, E-mail: da-rom@live.ru; Semin, Alexander P., E-mail: romanov-da@physics.sibsiu.ru, E-mail: kos2906@mail.ru, E-mail: budovskih-ea@physics.sibsiu.ru, E-mail: gromov@physics.sibsiu.ru, E-mail: da-rom@live.ru [Siberian State Industrial University, Novokuznetsk, 654007 (Russian Federation)

    2014-11-14

    For the first time, the high intensity electron beam modification of electroexplosion composite coatings of MoCu, MoCCu, WCu, WCCu and TiB{sub 2}Cu systems was done. The studies of phase and elemental composition, defective structure conditions of these coatings were carried out. The regimes of electron-beam processing making possible to form the dense, specular luster surface layers having a submicrocrystalline structure were revealed. It was established that electron-beam processing of elecroexplosion spraying of layer of elecroexplosion spraying carried out in the regime of melting results in the formation of structurally and contrationally homogeneous surface layer. Investigation of the effect of electron-beam processing of electroexplosion electroerosion resistant coatings on their tribological properties (wear resistanse and coefficient of friction) and electroerosion resistance was done. It was shown that all the examined costings demonstrate the increase of electroerosion resistance in spark erosion up to 10 times.

  13. In vitro evaluation of fracture resistance of Fiber-Reinforced Composite inlay bridges in upper anterior and lower posterior teeth

    Directory of Open Access Journals (Sweden)

    Jalalian E.

    2007-07-01

    Full Text Available Background and Aim: Considering flexural strength of fiber-reinforced composites (FRC and also the role of conservative cavities in protecting sound tissue of abutments, the aim of this study was to evaluate the fracture resistance of these bridges by handmade samples in vitro.Materials and Methods: In this experimental in vitro study, 44 sound newly extracted teeth were used to make 22 fixed inlay bridges including 11 three unit anterior upper inlay bridges substituting clinical model of upper central and 11 three unit posterior lower inlay bridges substituting clinical model of lower first molar. Specimens were prepared with FRC and mounted with artificial PDL in acryl. Cases were exposed to final load by using Universal Testing Machine (Instron 1195 with the speed of 1 mm/min. Statistical analysis was performed by Kolmogorov- Smirnov, independent sample T and Kaplan-Meier tests with p<0.05 as the level of significance.Results: Based on the statistical tests, the 95% confidence interval of mean was 450-562 N in anterior and  1473- 1761 N in posterior area. Fracture strength was high in the studied groups. Fractures in both groups occurred on composite facing, and the framework remained intact. The highest percentage of fracture in posterior teeth was in the middle of pontic towards the distal connector and in the anterior teeth in the lateral connector, between central pontic and lateral abutment. Using the independent sample T  test a significant statistical difference was observed between two groups (P<0.001. The fracture resistance of anterior samples was lower than the posterior ones.Conclusion: Based on the results of this study regarding the high fracture resistance in both areas FRC inlay bridges could be recommended for upper anterior and lower posterior teeth in clinical dentistry certainly more studies are needed to ascertain this treatment option.

  14. Effect of fed- versus fasted state resistance training during Ramadan on body composition and selected metabolic parameters in bodybuilders

    Science.gov (United States)

    2013-01-01

    Background Muslim bodybuilders often continue training during Ramadan. However, the effect of resistance training in a fasted versus a fed state during Ramadan on body composition and metabolic parameters in bodybuilders is not well known. The aim of this study was to evaluate the effects of resistance training in a fasted versus a fed state during Ramadan on body composition and metabolic parameters in bodybuilders. Methods Sixteen men were allocated to two groups: Eight practicing resistance training in the late afternoon in a fasted state (FAST), and eight training in the late evening in an acutely fed state (FED) during Ramadan. All visited the laboratory in the morning two days before the start of Ramadan (Bef-R) and on the 29th day of Ramadan (End-R) for anthropometric measurement, completion of a dietary questionnaire, and provision of fasting blood and urine samples. Results Body mass and body fat percentage remained unchanged in FAST and FED during the whole period of the investigation. Both FAST and FED experienced an increase in the following parameters from Bef-R to End-R: urine specific gravity (1%; p = 0.028, p = 0.004 respectively), serum concentrations of urea (4%, p = 0.006; 7%, p = 0.004 respectively), creatinine (5%, p = 0.015; 6%, p = 0.04 respectively), uric acid (17%; p bodybuilders. Additionally, Ramadan fasting induced changes in urinary and some biochemical parameters, but these changes were not different according to when the training occurred. PMID:23617897

  15. Fatigue resistance and crack propensity of large MOD composite resin restorations: direct versus CAD/CAM inlays.

    Science.gov (United States)

    Batalha-Silva, Silvana; de Andrada, Mauro Amaral Caldeira; Maia, Hamilton Pires; Magne, Pascal

    2013-03-01

    To assess the influence of material/technique selection (direct vs. CAD/CAM inlays) for large MOD composite adhesive restorations and its effect on the crack propensity and in vitro accelerated fatigue resistance. A standardized MOD slot-type tooth preparation was applied to 32 extracted maxillary molars (5mm depth and 5mm bucco-palatal width) including immediately sealed dentin for the inlay group. Fifteen teeth were restored with direct composite resin restoration (Miris2) and 17 teeth received milled inlays using Paradigm MZ100 block in the CEREC machine. All inlays were adhesively luted with a light curing composite resin (Filtek Z100). Enamel shrinkage-induced cracks were tracked with photography and transillumination. Cyclic isometric chewing (5 Hz) was simulated, 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. Samples were loaded until fracture or to a maximum of 185,000 cycles. Teeth restored with the direct technique fractured at an average load of 1213 N and two of them withstood all loading cycles (survival=13%); with inlays, the survival rate was 100%. Most failures with Miris2 occurred above the CEJ and were re-restorable (67%), but generated more shrinkage-induced cracks (47% of the specimen vs. 7% for inlays). CAD/CAM MZ100 inlays increased the accelerated fatigue resistance and decreased the crack propensity of large MOD restorations when compared to direct restorations. While both restorative techniques yielded excellent fatigue results at physiological masticatory loads, CAD/CAM inlays seem more indicated for high-load patients. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  16. Sliding wear resistance of metal matrix composite layers prepared by high power laser

    NARCIS (Netherlands)

    Ocelik, Vaclav; Matthews, D; de Hosson, Jeff

    2005-01-01

    Two laser surface engineering techniques, Laser Cladding and Laser Melt Injection (LMI), were used to prepare three different metal matrix composite layers with a thickness of about 1 mm and approximately 25-30% volume fraction of ceramic particles. SiC/Al-8Si, WC/Ti-6Al-4V and TiB2/Ti-6Al-4V layers

  17. Biological resistance of polyethylene composites made with chemically modified fiber or flour

    Science.gov (United States)

    Rebecca E. Ibach; Craig M. Clemons

    2002-01-01

    The role of moisture in the biological decay of wood-plastic composites was investigated. Southern pine wood fiber and ponderosa pine wood flour were chemically modified using either acetic anhydride (AA), butylene oxide (BO), or propylene oxide (PO). A 50:50 mixture of high density polyethylene and either chemically modified fiber or flour, or untreated fiber or flour...

  18. Characterization of nano-composite PVD coatings for wear-resistant applications

    NARCIS (Netherlands)

    Galvan, D.; Pei, Y.T.; de Hosson, J.T.M.; DeHosson, JTM; Brebbia, CA; Nishida, SI

    2005-01-01

    Various methodologies for the characterization of nano-composite coatings are discussed, which consist TiC nano-particles distributed in an amorphous hydrocarbon (a-C:H) matrix. Complications that arise from the influence of coating roughness and underlying substrate on the properties are evaluated

  19. The Impact Resistance of Fiber-Reinforced Polymer Composites: A Review

    Directory of Open Access Journals (Sweden)

    Mahmood Mehrdad Shokrieh

    2012-12-01

    Full Text Available Fiber reinforced composites are widely used instead of traditional materials in various technological applications. Therefore, by considering the extensive applications of these materials, a proper knowledge of their impact behavior (from low- to high-velocity as well as their static behavior is necessary. In order to study the effects of strain rates on the behavior of these materials, special testing machines are needed. Most of the research efforts in this feld are focused on application of real loading and gripping boundary conditions on the testing specimens. In this paper, a detailed review of different types of impact testing techniques and the strain rate dependence of mechanical and strength properties of polymer composite materials  are presented. In this respect, an attempt is made to present and summarize the methods of impact tests and the strain rate effects on the tensile, compressive, shear and bending properties of the fber-reinforced polymer composite materials. Moreover, a classifcation of the state-of-the-art of the testing techniques to characterize composite material properties in a wide range of strain rates are also given.

  20. Resistance pressure sensor based on Ag/Cu/sub 2/O-PEPC-NiPc/Al composite

    International Nuclear Information System (INIS)

    Khan, A.; Karimov, K.S.; Shah, M.

    2011-01-01

    This work reports on the fabrication and investigation of pressure sensor based on Ag/Cu/sub 2/O-PEPC-NiPc/Al composite. The active layer of the composite was deposited by drop-casting of the blend Cu/sub 2/O-PEPC-NiPc on flexible substrate. The thin film of the blend consist of cuprous oxide (Cu/sub 2/O) micropowder, (5 wt. %), poly-N-epoxypropyl carbazole (PEPC), (2 wt. %) and nickel phthalocyanine (NiPc) micropowder, (3 wt. %) in benzol (1 ml). The film thickness of the composite is in the range of 20-30 mu m. It is found that the fabricated sensor is sensitive to pressure and showed good repeatability. The decrease in resistance of the sensor is observed 10 times by increasing the external uniaxial pressure up to 11.7 kNm/sup -2/. The experimentally obtained results are compared with the simulated results and showed reasonable agreement with each other. (author)

  1. Research of the Fire Resistance оf Translucent and Composite Facade System

    Directory of Open Access Journals (Sweden)

    Nedryshkin Oleg

    2016-01-01

    Full Text Available The paper aims at researching fire resistance of a prototype facade system “Technocom” (type Alucobond A2. Experimental and theoretical research of fire hazard facade system is carried out. The objectives of the study are to determine compliance with the applicable front of special technical requirements. The status of problem reducing fire hazard facade system is reviewed. The method developed by compensatory measures is applied.

  2. Blast-Resistant Improvement of Sandwich Armor Structure with Aluminum Foam Composite

    OpenAIRE

    Yang, Shu; Qi, Chang

    2013-01-01

    Sandwich armor structures with aluminum foam can be utilized to protect a military vehicle from harmful blast load such as a landmine explosion. In this paper, a system-level dynamic finite element model is developed to simulate the blast event and to evaluate the blast-resistant performance of the sandwich armor structure. It is found that a sandwich armor structure with only aluminum foam is capable of mitigating crew injuries under a moderate blast load. However, a severe blast load causes...

  3. Chemical composition and antibacterial activities of Illicium verum against antibiotic-resistant pathogens.

    Science.gov (United States)

    Yang, Jyh-Ferng; Yang, Cheng-Hong; Chang, Hsueh-Wei; Yang, Cheng-San; Wang, Shao-Ming; Hsieh, Ming-Che; Chuang, Li-Yeh

    2010-10-01

    In recent years, human pathogenic microorganisms have developed multiple drug resistance and caused serious nosocomial infections. In this study, we identified four new antimicrobial compounds from the Chinese herbal medicine Illicium verum and assessed their antibacterial efficacies. The supercritical CO₂ and ethanol extracts of Illicium verum showed substantial antibacterial activity against 67 clinical drug-resistant isolates, including 27 Acinetobacter baumannii, 20 Pseudomonas aeruginosa, and 20 methicillin-resistant Staphylococcus aureus. The diethyl ether (EE) fraction obtained from partition extraction and supercritical CO₂ extracts revealed an antibacterial activity with a minimum inhibitory concentration value of 0.15-0.70 mg/mL and 0.11 mg/mL, respectively. The EE fraction of I. verum showed synergetic effects with some commercial antibiotics. The antimicrobial mechanism was investigated with killing curves and scanning electron microscopy observation. The chemical components of the extracts were analyzed by spectrophotometry; (E)-anethole, anisyl acetone, anisyl alcohol, and anisyl aldehyde exhibited antibacterial activity against different clinical isolates. These extracts from I. verum can be further developed into antibiotic medicines due to their proven antibacterial activity.

  4. Toward advanced gamma rays radiation resistance and shielding efficiency with phthalonitrile resins and composites

    Science.gov (United States)

    Derradji, Mehdi; Zegaoui, Abdeldjalil; Xu, Yi-Le; Wang, An-ran; Dayo, Abdul Qadeer; Wang, Jun; Liu, Wen-bin; Liu, Yu-Guang; Khiari, Karim

    2018-04-01

    The phthalonitrile resins have claimed the leading place in the field of high performance polymers thanks to their combination of outstanding properties. The present work explores for the first time the gamma rays radiation resistance and shielding efficiency of the phthalonitrile resins and its related tungsten-reinforced nanocomposites. The primary goal of this research is to define the basic behavior of the phthalonitrile resins under highly ionizing gamma rays. The obtained results confirmed that the neat phthalonitrile resins can resist absorbed doses as high as 200 kGy. Meanwhile, the remarkable shielding efficiency of the phthalonitrile polymers was confirmed to be easily improved by preparing lead-free nanocomposites. In fact, the gamma rays screening ratio reached the exceptional value of 42% for the nanocomposites of 50 wt% of nano-tungsten loading. Thus, this study confirms that the remarkable performances of the phthalonitrile resins are not limited to the thermal and mechanical properties and can be extended to the gamma rays radiation and shielding resistances.

  5. The Effect of 10 Weeks of Resistance Training on Serum Myostatin and Body Composition Levels in Obese Adolescents

    Directory of Open Access Journals (Sweden)

    Mohammad ebrahim Bahram

    2017-06-01

    Full Text Available Background and Objectives: Studies are indicative of negative regulatory role of myostatin in skeletal muscle growth. In the present study, the effect of 10 weeks of resistance training was investigated on serum level of myostatin and body composition in obese adolescents. Methods: In this quasi-experimental study, 16 students of Mohammad Naraghi Technical and Vocational Institute of Kashan with body mass index of 30-35, were purposefully selected and randomly divided into two groups of experimental and control. Resistance training program included 3 sets of 8-10 reps with 50-90% 1RM for 3 days a week. Before starting the training program and 48 h after the last training session, blood samples were taken from all participants. Before and after the training, plasma level of myostatin were measured. Data were analyzed using Kolmogorov-Smirnov, dependent t-, and independent t-tests at significance level of p<0.05. Results: In this study, 10 weeks of resistance training resulted in a significant decrease in serum level of myostatin (p=0.0001, weight (p=0.015, body mass index (p=0.02, and fat percentage (p=0.0001 in the experimental group as compared to the control group (p<0.05. Conclusion: According to the findings of the current study, it can be concluded that resistance training-induced changes reduce myostatin level and some anthropometric parameters related to obesity and overweight, which may be effective in the prevention of muscle atrophy and loss of muscle mass, and can play a role as an autocrine mechanism for guiding mechanical load stimuli in response to the growth of skeletal muscle.

  6. The concept of a novel hybrid smart composite reinforced with radially aligned zigzag carbon nanotubes on piezoelectric fibers

    International Nuclear Information System (INIS)

    Ray, M C

    2010-01-01

    A new hybrid piezoelectric composite (HPZC) reinforced with zigzag single-walled carbon nanotubes (CNTs) and piezoelectric fibers is proposed. The novel constructional feature of this composite is that the uniformly aligned CNTs are radially grown on the surface of piezoelectric fibers. A micromechanics model is derived to estimate the effective piezoelectric and elastic properties. It is found that the effective piezoelectric coefficient e 31 of the proposed HPZC, which accounts for the in-plane actuation, is significantly higher than that of the existing 1-3 piezoelectric composite without reinforcement with carbon nanotubes and the previously reported hybrid piezoelectric composite (Ray and Batra 2009 ASME J. Appl. Mech. 76 034503)

  7. Thermal shock resistance of ceramic fibre composites characterized by non-destructive methods

    Directory of Open Access Journals (Sweden)

    M. Dimitrijević

    2008-12-01

    Full Text Available Alumina based ceramic fibres and alumina based ceramic were used to produce composite material. Behaviour of composite ceramics after thermal shock treatments was investigated. Thermal shock of the samples was evaluated using water quench test. Surface deterioration level of samples was monitored by image analysis before and after a number of quenching cycles. Ultrasonic measurements were done on samples after quench tests. Dynamic Young modulus of elasticity and strength degradation were calculated using measured values of ultrasonic velocities. Strengths deterioration was calculated using the non-destructive measurements and correlated to degradation of surface area and number of quenches. The addition of small amount of ceramic fibres improves the strengths and diminishes the loss of mechanical properties of samples during thermal shock experiments.

  8. Surge-Resistant Nanocomposite Enameled Wire Using Silica Nanoparticles with Binary Chemical Compositions on the Surface

    Directory of Open Access Journals (Sweden)

    Jeseung Yoo

    2015-01-01

    Full Text Available We developed polyesterimide (PEI nanocomposite enameled wires using surface-modified silica nanoparticles with binary chemical compositions on the surface. The modification was done using silanes assisted by ultrasound, which facilitated high density modification. Two different trimethoxysilanes were chosen for the modification on the basis of resemblance of chemical compositions on the silica surface to PEI varnish. The surface-modified silica was well dispersed in PEI varnish, which was confirmed by optical observation and viscosity measurement. The glass transition temperature of the silica-PEI nanocomposite increased with the silica content. The silica-dispersed PEI varnish was then used for enameled wire fabrication. The silica-PEI nanocomposite enameled wire exhibited a much longer lifetime compared to that of neat PEI enameled wire in partial discharge conditions.

  9. The role of microcracking on the crack growth resistance of brittle solids and composites

    International Nuclear Information System (INIS)

    Biner, S.B.

    1994-01-01

    A set of numerical analyses of crack growth was preformed to elucidate the influence of microcracking on the fracture behavior of microcracking brittle solids and composites. The random nucleation, orientation and size effects of discrete nucleating microcracks and resulting interactions are fully accounted for in a hybrid finite element model. The results obtained from the finite element analysis are compared with the continuum description of the microcracking. Although continuum description can provide a reasonable estimation of shielding, it fails to resolve the details of micromechanism of toughening resulting from microcracking, since not every shielding event during the course of crack extension corresponds to an increase in the R-curve. Moreover, as seen in the composite cases, the local events leading to toughening behavior may not be associated with the microcracking even in the presence of a large population of microcracks

  10. Composition

    DEFF Research Database (Denmark)

    Bergstrøm-Nielsen, Carl

    2014-01-01

    Cue Rondo is an open composition to be realised by improvising musicians. See more about my composition practise in the entry "Composition - General Introduction". Caution: streaming the sound/video files will in some cases only provide a few minutes' sample, or the visuals will not appear at all....... Please DOWNLOAD them to see/hear them in full length! This work is licensed under a Creative Commons "by-nc" License. You may for non-commercial purposes use and distribute it, performance instructions as well as specially designated recordings, as long as the author is mentioned. Please see http...

  11. Composition and adaptation of human myotendinous junction and neighboring muscle fibers to heavy resistance training

    DEFF Research Database (Denmark)

    Jakobsen, Jens R.; Mackey, A L; Knudsen, A B

    2017-01-01

    The myotendinous junction (MTJ) is a common site of strain injury and yet understanding of its composition and ability to adapt to loading is poor. The main aims of this study were to determine the profile of selected collagens and macrophage density in human MTJ and adjoining muscle fibers...... 4 weeks of training may reflect a training-induced protection against strain injuries in this region....

  12. Wear resistant composite structure of vitreous carbon containing convoluted fibers. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Burton, R.G.; Burton, R.A.

    1996-05-28

    Energy Related Inventions Program Number 613 was a two year program to commercialize a unique new wear material, Metal Reinforced Carbon Composite, MRCC. The program was designed to manufacture sample components of MRCC for evaluation by potential users and manufacturers. As a result of the program Burton Technologies Inc. and Rotary Power International are forming a joint company to manufacture, market and license MRCC materials to a wide range of industries.

  13. The Impact Resistance of Fiber-Reinforced Polymer Composites: A Review

    OpenAIRE

    Mahmood Mehrdad Shokrieh; Majid Jamal Omidi

    2012-01-01

    Fiber reinforced composites are widely used instead of traditional materials in various technological applications. Therefore, by considering the extensive applications of these materials, a proper knowledge of their impact behavior (from low- to high-velocity) as well as their static behavior is necessary. In order to study the effects of strain rates on the behavior of these materials, special testing machines are needed. Most of the research efforts in this feld are focused on application ...

  14. A New Design of In Situ Ti(C,N) Reinforced Composite Coatings and Their Microstructures, Interfaces, and Wear Resistances.

    Science.gov (United States)

    Wang, Mingliang; Cui, Hongzhi; Wei, Na; Ding, Lei; Zhang, Xinjie; Zhao, Yong; Wang, Canming; Song, Qiang

    2018-01-31

    Here, a unique combination of a novel carbon-nitrogen source (g-C 3 N 4 ) with different mole ratios of Ti/g-C 3 N 4 has been utilized to fabricate iron matrix composite coatings by a synchronized powder feeding plasma transferred arc (PTA) cladding technology. The results show that submicron Ti(C,N) particles are successfully fabricated in situ on a Q235 low carbon steel substrate to reinforce the iron matrix composite coatings and exhibit dense microstructures and good metallurgical bonding between the coating and the substrate. The microstructure of the coating consists of an α-Fe matrix and Ti(C,N) particles when the mole ratio of Ti/g-C 3 N 4 is no more than 5:1. The microhardness and wear resistance of the coating gradually improve with increasing abundance of the in-situ-synthesized Ti(C,N) particles. Interestingly, for a Ti/g-C 3 N 4 mole ratio of 6:1, a fine lamellar eutectic Laves phase (Fe 2 Ti) appears, and this phase further improves the microhardness and wear resistance of the coating. The microhardness of the coating is 3.5 times greater than that of the Q235 substrate, and the wear resistance is enhanced 7.66 times over that of the substrate. The Ti(C,N)/Fe 2 Ti and Fe 2 Ti/α-Fe interfaces are very clean, and the crystallographic orientation relationships between the phases are analyzed by high-resolution transmission electron microscopy (HRTEM) and an edge-to-edge matching model. The theoretical predictions and the experimental results are in good agreement. Furthermore, based on the present study, for the solidification process near equilibrium, smaller interatomic spacing misfits and interplanar spacing d-value mismatches contribute to the formation of crystallographic orientation relationships between phases during the PTA cladding process. The existence of orientation relationships is beneficial for improving the properties of the coatings. This work not only expands the application fields of g-C 3 N 4 but also provides a new idea for the

  15. Effects of coal composition and flotation reagents on the water resistance of binderless briquettes

    Energy Technology Data Exchange (ETDEWEB)

    Motaung, S.R.; Mangena, S.J.; de Korte, G.J. [Syngas & Coal Technology, Sasolburg (South Africa)

    2007-10-15

    The difference in the physical properties, particularly the water resistance or wet strength, of the binderless coal briquettes produced from flotation feed and concentrate was investigated using six bituminous coals from two collieries in the Witbank Coalfield. The coal samples were analyzed for their proximate, petrographic, and mineralogical properties. The presence, in the flotation concentrates, of the reagents used during the froth flotation process was also investigated using gas chromatography. Pillow-shaped binderless briquettes were produced from coal samples at various moisture contents and a pressure of approximately 17 MPA using a Komarek B-100A double-roll press. The briquettes were tested for some physical properties (i.e., dry- and wet-compressive strengths), which were thereafter compared with the properties determined for the coal samples. The binderless briquettes produced from the flotation concentrates were more water-resistant than those produced from the flotation feed. The flotation feed and concentrates of the coals tested were found to have similar petrographic properties. As expected, the ash and kaolinite contents were found to be lower in the flotation concentrates than in the flotation feed. Flotation reagents were detected in the flotation concentrates from both collieries. From the results obtained it is concluded that the increased water resistance of the binderless briquettes produced from flotation concentrates of the coals tested is due to a combination of the fineness of the coal particles, assisted by the amount of reactive macerals (most particularly vitrinite) with the lower ash and kaolinite contents, together with the presence of the flotation reagents, particularly the collector, in the flotation concentrate.

  16. Bistable resistive memory behavior in gelatin-CdTe quantum dot composite film

    Science.gov (United States)

    Vallabhapurapu, Sreedevi; Rohom, Ashwini; Chaure, N. B.; Du, Shengzhi; Srinivasan, Ananthakrishnan

    2018-05-01

    Bistable memory behavior has been observed for the first time in gelatin type A thin film dispersed with functionalized CdTe quantum dots. The two terminal device with the polymer nanocomposite layer sandwiched between an indium tin oxide coated glass plate and an aluminium top electrode performs as a bistable resistive random access memory module. Butterfly shaped (O-shaped with a hysteresis in forward and reverse sweeps) current-voltage response is observed in this device. The conduction mechanism leading to the bistable electrical switching has been deduced to be a combination of ohmic and electron hopping.

  17. Alteration in lipid composition of plasma membranes of sensitive and resistant Guerin carcinoma cells due to the action of free and liposomal form of cisplatin.

    Science.gov (United States)

    Naleskina, L A; Todor, I N; Nosko, M M; Lukianova, N Y; Pivnyuk, V M; Chekhun, V F

    2013-09-01

    To study in vivo changes of lipid composition of plasma membranes of sensitive and resistant to cisplatin Guerin carcinoma cells under influence of free and liposomal cisplatin forms. The isolation of plasma membranes from parental (sensitive) and resistant to cisplatin Guerin carcinoma cells was by differential ultracentrifugation in sucrose density gradient. Lipids were detected by method of thin-layer chromatography. It was determined that more effective action of cisplatin liposomal form on resistant cells is associated with essential abnormalities of conformation of plasma membrane due to change of lipid components and architectonics of rafts. It results in the increase of membrane fluidity. Reconstructions in lipid composition of plasma membranes of cisplatin-resistant Guerin carcinoma cells provide more intensive delivery of drug into the cells, increase of its concentration and more effective interaction with cellular structural elements.

  18. Development of high temperature resistant ceramic matrix composites based on SiC- and novel SiBNC-fibres

    International Nuclear Information System (INIS)

    Daenicke, Enrico

    2014-01-01

    Novel ceramic fibres in the quaternary system Si-B-C-N exhibit excellent high temperature stability and creep resistance. In th is work it was investigated, to what extent these outstanding properties of SiBNC-fibres can be transferred into ceramic matrix composites (CMC) in comparison to commercial silicon carbide (SiC) fibres. For the CMC development the liquid silicon infiltration (LSI) as well as the polymer infiltration and pyrolysis process (PIP) was applied. Extensive correlations between fibre properties, fibre coating (without, pyrolytic carbon, lanthanum phosphate), process parameters of the CMC manufacturing method and the mechanical and microstructural properties of the CMC before and after exposure to air could be established. Hence, the potential of novel CMCs can be assessed and application fields can be derived.

  19. A new discrete-element approach for the assessment of the seismic resistance of composite reinforced concrete-masonry buildings

    International Nuclear Information System (INIS)

    Calio, I.; Cannizzaro, F.; Marletta, M.; Panto, B.; D'Amore, E.

    2008-01-01

    In the present study a new discrete-element approach for the evaluation of the seismic resistance of composite reinforced concrete-masonry structures is presented. In the proposed model, unreinforced masonry panels are modelled by means of two-dimensional discrete-elements, conceived by the authors for modelling masonry structures, whereas the reinforced concrete elements are modelled by lumped plasticity elements interacting with the masonry panels through nonlinear interface elements. The proposed procedure was adopted for the assessment of the seismic response of a case study confined-masonry building which was conceived to be a typical representative of a wide class of residential buildings designed to the requirements of the 1909 issue of the Italian seismic code and widely adopted in the aftermath of the 1908 earthquake for the reconstruction of the cities of Messina and Reggio Calabria

  20. Thioridazine Induces Major Changes in Global Gene Expression and Cell Wall Composition in Methicillin-Resistant Staphylococcus aureus USA300

    DEFF Research Database (Denmark)

    Thorsing, Mette; Klitgaard, Janne Kudsk; Atilano, Magda L.

    2013-01-01

    and the transcriptomic response of S. aureus to known inhibitors of cell wall synthesis suggests that TDZ disturbs PGN biosynthesis at a stage that precedes transpeptidation by penicillin-binding proteins (PBPs). In support of this notion, dramatic changes in the muropeptide profile of USA300 were observed following....... In the present study, we have examined the effect of a subinhibitory concentration of TDZ on antimicrobial resistance, the global transcriptome, and the cell wall composition of MRSA USA300. We show that TDZ is able to sensitize the bacteria to several classes of antimicrobials targeting the late stages...... a major impact on the cell wall biosynthesis pathway in S. aureus and provides new insights into how MRSA may be sensitized towards β-lactam antibiotics....

  1. Creep behavior and wear resistance of Al 5083 based hybrid composites reinforced with carbon nanotubes (CNTs) and boron carbide (B{sub 4}C)

    Energy Technology Data Exchange (ETDEWEB)

    Alizadeh, Ali [Faculty of Materials & Manufacturing Processes, Malek-e-Ashtar University of Technology, Tehran (Iran, Islamic Republic of); Abdollahi, Alireza, E-mail: alirezaabdollahi1366@gmail.com [Faculty of Materials & Manufacturing Processes, Malek-e-Ashtar University of Technology, Tehran (Iran, Islamic Republic of); Biukani, Hootan [Faculty of Engineering, South Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2015-11-25

    In the current research, aluminum based hybrid composite reinforced with boron carbide (B{sub 4}C) and carbon nanotubes (CNTs) was produced by powder metallurgy method. creep behavior, wear resistance, surface roughness, and hardness of the samples were investigated. To prepare the samples, Al 5083 powder was milled with boron carbide particles and carbon nanotubes using planetary ball mill under argon atmosphere with ball-to-powder weight ratio of 10:1 for 5 h. Afterwards, the milled powders were formed by hot press process at 380{sup °}C and then were sintered at 585{sup °}C under argon atmosphere for 2 h. There was shown to be an increase in hardness values of composite with an increase in B{sub 4}C content. The micrograph of worn surfaces indicate a delamination mechanism due to the presence of CNTs and abrasion mechanism in composite containing 10 vol.%B{sub 4}C. Moreover, it was shown that increasing B{sub 4}C content increases the wear resistance by 3 times under a load of 20 N and 10 times under a load of 10 N compared to CNTs-reinforced composite. surface roughness of the composite containing 5 vol.%CNT has shown to be more than other samples. The results of creep test showed that adding carbon nanotubes increases creep rate of Al 5083 alloy; however, adding B{sub 4}C decreases its creep rate. - Highlights: • Al 5083/(CNTs + B{sub 4}C) hybrid composite was produced by powder metallurgy method. • Creep behavior, wear resistance, surface roughness, and Hardness of samples were investigated. • Addition of CNTs to Al 5083 matrix reduces alloy hardness, wear resistance and creep strength. • By addition of B{sub 4}C and composite hybridization, creep strength and wear resistance increased. • Surface roughness of Al-5 vol.%CNT has shown to be more than other samples.

  2. Concept - or no concept

    DEFF Research Database (Denmark)

    Thorsteinsson, Uffe

    1999-01-01

    Discussion about concept in industrial companies. A method for mapping of managerial concept in specific area is shown......Discussion about concept in industrial companies. A method for mapping of managerial concept in specific area is shown...

  3. Silk Composite with a Fluoropolymer as a Water-Resistant Protein-Based Material

    Directory of Open Access Journals (Sweden)

    Keiji Numata

    2018-04-01

    Full Text Available Silk-based materials are water-sensitive and show different physical properties at different humidities and under wet/dry conditions. To overcome the water sensitivity of silk-based materials, we developed a silk composite material with a fluoropolymer. Blending and coating the silk protein-based materials, such as films and textiles, with the fluoropolymer enhanced the surface hydrophobicity, water vapor barrier properties, and size stability during shrinkage tests. This material design with a protein biopolymer and a fluoropolymer is expected to broaden the applicability of protein-based materials.

  4. Effect of inclusion of SiC particulates on the mechanical resistance behaviour of stir-cast AA6063/SiC composites

    International Nuclear Information System (INIS)

    Balasubramanian, I.; Maheswaran, R.

    2015-01-01

    Highlights: • AA6063/SiC composites with different weight percent are stir cast. • Resistance properties against indentation, stretching force and sliding force are studied. • Increase in initiation of cleavage facets and reduces the tensile strength for 15% SiC. • Transition from micro ploughing to micro cutting wear mechanism is less due to SiC inclusion. - Abstract: This study investigates the mechanical resistance behaviour of AA6063 particulate composites with the inclusion of micron-sized silicon carbide (SiC) particles with different weight percentages in an AA6063 aluminium matrix. AA6063/SiC particulate composites containing 0, 5, 10, and 15 weight percent of SiC particles were produced by stir casting. Standard mechanical tests were conducted on the composite plates, and the mechanical resistance to indentation, tensile force and sliding force are evaluated. It has been observed that upon addition of SiC particles, the resistance against indentation is increased and the resistance against tensile force is initially increased and then decreased. Furthermore, using scanning electron microscopy (SEM), the fracture appearance of the broken specimen subjected to tensile force and morphological changes in the surface subjected to sliding force are analysed. The SEM images reveal that the addition of SiC particles in the AA6063 aluminium matrix initiates more cleavage facets. This leads to brittle fracture in the specimen subjected to tensile forces and less transition from material displacement to material removal in the specimen subjected to sliding forces

  5. Nesfatin-1 in childhood and adolescent obesity and its association with food intake, body composition and insulin resistance.

    Science.gov (United States)

    Anwar, Ghada M; Yamamah, Gamal; Ibrahim, Amani; El-Lebedy, Dalia; Farid, Tarek M; Mahmoud, Rasha

    2014-01-10

    Nesfatin-1 is an anorexigenic peptide that controls feeding behavior and glucose homeostasis. However, there is little data that exists regarding nesfatin-1 secretion in obese children and young adolescents. The aim of this study is to investigate serum nesfatin-1 in childhood and adolescent obesity and to study potential correlations with food intake, anthropometric indices, body composition and insulin resistance. Forty obese children and adolescents and 40 healthy control subjects were studied. Anthropometric measurements were assessed, dietary food intake was evaluated based on 3-days food record and body composition indices were evaluated using bioelectrical impedance analysis. Lipid profile, fasting blood sugar, fasting insulin and HOMA-IR were measured. Fasting serum nesfatin-1 was quantitatively assayed by ELISA. Serum nesfatin-1 was significantly higher in obese group (2.49±1.96 ng/ml) than in control group (0.70±0.81 ng/ml), P=0.001. Positive correlations with serum insulin (P=0.001), HOMA-IR (P=0.000), BMI-SDS (P=0.04), body fat % (P=0.000), fat mass (P=0.000), fat free mass (P=0.03), CHO % (P=0.000), and saturated fat % (P=0.01) were found. While significant negative correlation with protein % (P=0.000) was observed. In conclusion, our results denote that nesfatin-1 might have an important role in regulation of food intake and pathogenesis of insulin resistance in obese children and young adolescents. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Improved corrosion resistant and mechanical behavior of distinct composite coatings (silica/titania/zirconia on Ti–6Al–4V deposited by EPD

    Directory of Open Access Journals (Sweden)

    M. Chellappa

    2017-09-01

    Full Text Available Synthesized composite powders (ZrO2/TiO2, SiO2/TiO2, and SiO2/ZrO2 were successfully deposited on Ti–6Al–4V by electrophoretic deposition method (EPD to improve its electrochemical characteristics for better biomedical applications. In the present investigation, the three composite powders were prepared by sol–gel synthesis and its phase purity was analyzed by Powder X-ray diffraction (XRD method. Further, the performance of the deposited coatings was assessed by scanning electron microscopy (SEM coupled with energy dispersive X-ray analysis (EDAX, scratch resistance test. The electrochemical properties of the composite coatings were analyzed by Potentiodynamic (Tafel polarization and electrochemical impedance spectroscopy (EIS studies. From the results, we observed that the corrosion resistance behavior of the different composite coated metallic substrate exhibited divergent corrosion resistance nature than blank Ti–6Al–4V. Of all these coatings on Ti–6Al–4V, the composite made up of, ZrO2/TiO2 has pronounced corrosion resistance behavior in Ringer’s solution when compared to others. This behavior is due to the presence of strong adherent coating owing to the existence of uniform deposition on Ti–6Al–4V.

  7. Electrical Resistivity Correlation to Vadose Zone Sediment and Pore-Water Composition for the BC Cribs and Trenches Area

    International Nuclear Information System (INIS)

    Serne, R. Jeffrey; Ward, Anderson L.; Um, Wooyong; Bjornstad, Bruce N.; Rucker, Dale F.; Lanigan, David C.; Benecke, Mark W.

    2009-01-01

    This technical report documents the results of geochemical and soil resistivity characterization of sediment obtained from four boreholes drilled in the BC Cribs and Trench area. Vadose zone sediment samples were obtained at a frequency of about every 2.5 ft from approximately 5 ft bgs to borehole total depth. In total, 505 grab samples and 39 six-inch long cores were obtained for characterization. The pore-water chemical composition data, laboratory-scale soil resistivity and other ancillary physical and hydrologic measurements and analyses described in this report are designed to provide a crucial link between direct measurements on sediments and the surface-based electrical-resistivity information obtained via field surveys. A second goal of the sediment characterization was to measure the total and water-leachable concentrations of key contaminants of concern as a function of depth and distance from the footprints of inactive disposal facilities. The total and water-leachable concentrations of key contaminants will be used to update contaminant distribution conceptual models and to provide more data for improving base-line risk predictions and remedial alternative selections. The ERC 'ground truthing' exercise for the individual boreholes showed mixed results. In general, the high concentrations of dissolved salts in the pore waters of sediments from C5923, C5924 and C4191 produced a low resistivity 'target' in the processed resistivity field surveys, and variability could be seen in the resistivity data that could relate to the variability in pore- water concentrations but the correlations (regression R2 were mediocre ranging from 0.2 to 0.7 at best; where perfect correlation is 1.0). The field-based geophysical data also seemed to suffer from a sort of vertigo, where looking down from the ground surface, the target (e.g., maximum pore-water salt concentration) depth was difficult to resolve. The best correlations between the field electrical resistivity

  8. Electrical Resistivity Correlation to Vadose Zone Sediment and Pore-Water Composition for the BC Cribs and Trenches Area

    Energy Technology Data Exchange (ETDEWEB)

    Serne, R. Jeffrey; Ward, Anderson L.; Um, Wooyong; Bjornstad, Bruce N.; Rucker, Dale F.; Lanigan, David C.; Benecke, Mark W.

    2009-06-01

    This technical report documents the results of geochemical and soil resistivity characterization of sediment obtained from four boreholes drilled in the BC Cribs and Trench area. Vadose zone sediment samples were obtained at a frequency of about every 2.5 ft from approximately 5 ft bgs to borehole total depth. In total, 505 grab samples and 39 six-inch long cores were obtained for characterization. The pore-water chemical composition data, laboratory-scale soil resistivity and other ancillary physical and hydrologic measurements and analyses described in this report are designed to provide a crucial link between direct measurements on sediments and the surface-based electrical-resistivity information obtained via field surveys. A second goal of the sediment characterization was to measure the total and water-leachable concentrations of key contaminants of concern as a function of depth and distance from the footprints of inactive disposal facilities. The total and water-leachable concentrations of key contaminants will be used to update contaminant distribution conceptual models and to provide more data for improving base-line risk predictions and remedial alternative selections. The ERC “ground truthing” exercise for the individual boreholes showed mixed results. In general, the high concentrations of dissolved salts in the pore waters of sediments from C5923, C5924 and C4191 produced a low resistivity “target” in the processed resistivity field surveys, and variability could be seen in the resistivity data that could relate to the variability in pore- water concentrations but the correlations (regression R2 were mediocre ranging from 0.2 to 0.7 at best; where perfect correlation is 1.0). The field-based geophysical data also seemed to suffer from a sort of vertigo, where looking down from the ground surface, the target (e.g., maximum pore-water salt concentration) depth was difficult to resolve. The best correlations between the field electrical

  9. Melting of corrosion-resistant steel of martensite class with given phase composition

    International Nuclear Information System (INIS)

    Grashchenkov, P.M.; Kachanov, E.B.; Stetsenko, N.V.; Moshkevich, E.I.; Bunina, T.I.

    1979-01-01

    Introduced is a melting procedure for the EhP410U (vacuum arc remelted) and VNC-2M (electroslag remelted) stainless steels with carbon (carbon ferrochrome) and nickel additions to ensure a present phase composition. Magnetizability of cold specimens of the EhP410U steel should be within the limits 17.0-19.5 mV by a special device. During melting of the second steel controlled are not only cold specimens magnetizability of which should be not less than 16 mV, but hot as well (at 25O-400 deg C) by the level of magnetizability not higher than 0.5 mV. During vacuum arc remelting nitrogen content reduces in general by 0.014% and manganese content - by 0.23%; correspondingly the magnetizability of specimens insceases approximately by 1 mV. During electroslag remelting chemical and phase composition practically are not changed. Total and diffusible hydrogen contents in the vacuum remelted steel is rather low (1-5 and 0.03-0.35 cm 3 /100 gs), which provides increased reliability of the articles

  10. Phenolic composition, antioxidant capacity of Salvia verticcilata and effect on multidrug resistant bacteria by flow-cytometry.

    Science.gov (United States)

    Tekeli, Yener; Karpuz, Esra; Danahaliloglu, Hatice; Bucak, Serbay; Guzel, Yelda; Erdmann, Helmuth

    2014-01-01

    Antioxidants are of great importance for preventing oxidative stress that may cause several degenerative diseases. Studies have indicated phytochemicals have high free-radical scavenging activity, which helps to reduce the risk of chronic diseases. The aim of the present study is the determination of antioxidant properties, polyphenolic content and multidrug resistant bacteria of Salvia verticcilata L. Methanol was used as the extraction solvent. The total phenolic content was calculated using Folin-Ciocalteau method and phenolic composition was determined by HPLC. The radical scavenging activity of plant was evaluated in vitro based on the reduction of the stable DPPH free radical. The reducing capacity was identified by using the FRAP method. The ability of Salvia verticcilata L. to increase the permeability of multidrug resistant bacterial cells was conducted by flow cytometric assay on Listeria innocua and E-coli. The amount of total phenolics was found to be 347.5 mg GA/g extract. The IC50 value and FRAP assay are 0.61, and 0.944 respectively, Free radical scavenging effect and FRAP values are less than synthetic antioxidant compounds (BHA and BHT). Eight phenolic compounds were found in Salvia verticcilata L. Intense concentration of S. verticcilata L. has destroyed 97 % of living cells for Listeria innocua and 94.86% for E-coli. This study shows that methanolic extracts of Salvia verticcilata L. is a potential source of natural antioxidants and antimicrobial agent and can form the basis for pharmacological studies.

  11. Diets high in resistent starch and arabinoxylan modulate digestion processes and SCFA pool size in the large intestine and faecal microbial composition in pigs

    DEFF Research Database (Denmark)

    Nielsen, Tina Skau; Lærke, Helle Nygaard; Theil, Peter Kappel

    2014-01-01

    The effects of a high level of dietary fibre (DF) either as arabinoxylan (AX) or resistant starch (RS) on digestion processes, SCFA concentration and pool size in various intestinal segments and on the microbial composition in the faeces were studied in a model experiment with pigs. A total...... resulted in a 3- to 5-fold higher pool size of butyrate compared with WSD feeding, with the RSD being intermediate (P microbial composition towards butyrogenic...

  12. In vitro comparative analysis of resistance to compression of laboratory resin composites and a ceramic system

    Directory of Open Access Journals (Sweden)

    Montenegro Alexandre

    2010-01-01

    Full Text Available Background: Restorative materials must be capable not only of restoring the patient′s masticatory function, but also to rescue the self-esteem of those maculated by a disharmonious smile. Among the esthetic materials available on the market, the choice frequently lies between ceramic or indirect laboratory resin restorations. Aim: This study assessed the resistance to compression of two laboratory resins found on the market, namely Artglass ® and Targis ® , considering Omega 900 ® ceramic from Vita as control. Materials and Methods: With the aid of stainless steel matrices, with internal dimensions of 8.0 mm diameter at the base, 9.0 mm in the top portion and 4.0 mm height, 15 test specimens were made, being 5 of each material to be tested. The test specimens were kept in distilled water for 72 hours and submitted to an axial load by the action of a point with a rounded tip 2 mm in diameter, adapted to an EMIC 500 universal test machine. The compression speed was 0.5 mm/min, with a load cell capacity of 200 Kgf. Results: The means of the results were calculated in kilogram-force (Kgf. The results found were treated by analysis of variance (ANOVA and the differences found among the groups were identified by the Tukey test (5%. Conclusion: It was observed that the material Omega 900 ® offered significantly greater resistance to compression than the other two materials, which did not present statistically significant difference between them.

  13. Conception de couches minces tribologiques pour augmenter la resistance a l'erosion par impacts de particules

    Science.gov (United States)

    Hassani, Salim

    Solid particle erosion (SPE) is a serious problem in gas turbines, pumps, heat exchangers and piping systems in aircrafts and other applications. Sand and dust ingested by gas turbine engines may cause major damage to compressor gas path components, leading to severe performance degradation, excessive wear, increased maintenance and eventually premature failure of the engines. For the compressor section of aerospace gas turbine engines, in addition to the complex filtration systems used to screen the eroding particles, tribological coatings, such as TiN, Ti/TiN, CrN and TiAlN are used as protective layers of the base titanium alloy (Ti-6Al-4V) or stainless steels (17-4PH and 410) materials (substrates) against erosive wear. Such coatings can extend the service life of the components, but their performance still remains insufficient due to the complexity of failure mechanisms occurring upon SPE. Therefore, aerospace industry seeks to develop high performance coatings for the protection against erosion by solid particles. However, with many new materials used and tested for different applications and operation under different conditions, conducting experiments for each one of them is becoming increasingly difficult. Presently, coating selection criteria to prevent damage caused by erosion are based on trial and error experiments instead of prior design of coating's architecture and properties to maximize erosion resistance. The present work focuses on the use of advanced finite element (FE) methods to design erosion resistant (ER) coatings. It contributes a new methodology based on the analysis of transient stresses generated by a single impact event. Identification of coating architectures in which such stresses are minimized and crack propagation suppressed, allows one to predict and possibly minimize the erosion rate. Erosion mechanisms and governing erosion parameters are investigated to predict the coating behavior in simulated erosion conditions. The

  14. The effect of fibre layering pattern in resisting bending loads of natural fibre-based hybrid composite materials

    Directory of Open Access Journals (Sweden)

    Jusoh Muhamad Shahirul Mat

    2016-01-01

    Full Text Available The effect of fibre layering pattern and hybridization on the flexural properties of composite hybrid laminates between natural fibres of basalt, jute and flax with synthetic fibre of E-glass reinforced epoxy have been investigated experimentally. Results showed that the effect fibre layering pattern was highly significant on the flexural strength and modulus, which were strongly dependent on the hybrid configuration between sandwich-like (SL and intercalation (IC sequence of fibre layers. In addition, specific modulus based on the variation densities of the hybrid laminates was used to discover the best combination either basalt, jute or flax with E-glass exhibits superior properties concerning on the strength to weight-ratio. Generally, SL sequence of glass/basalt exhibited superior strength and stiffness compared with glass/jute and glass/flax in resisting bending loads. In terms of hybridization effect, glass/jute was found to be the best combination with E-glass compared to the rest of natural fibres investigated in the present study. Hence, the proper stacking sequences and material selection are among predominant factors that influence on mechanical properties and very crucial in designing composite hybrid system to meet the desired requirements.

  15. Corrosion resistance enhancement of Ni-P-nano SiO{sub 2} composite coatings on aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Sadreddini, Sina, E-mail: sina.sadreddini1986@gmail.com [Department of Materials Science and Engineering, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Afshar, Abdollah [Department of Materials Science and Engineering, Sharif university of Technology, Tehran (Iran, Islamic Republic of)

    2014-06-01

    In this study, the influences of different concentrations of SiO{sub 2} nano sized particles in the bath on deposition rate, surface morphology and corrosion behavior of Ni-P-SiO{sub 2} Composite coatings were investigated. The deposition rate of coating was influenced by incorporation of SiO{sub 2} particles. The microstructure was investigated with field emission scanning electron microscopy (FESEM). The amount of SiO{sub 2} was examined by Energy Dispersive Analysis of X-Ray (EDX) and amount of SiO{sub 2} nanoparticles co-deposited reached a maximum value at 4.5 %wt. Corrosion behavior of coated aluminum was evaluated by electrochemical impedance spectroscopy (EIS) and polarization techniques. The results illustrated that the corrosion rate decreases (6.5–0.6 μA/cm{sup 2}) and the corrosion potential increases (−0.64 to −0.3) with increasing the quantity of the SiO{sub 2} nanoparticles in the bath. Moreover, Ni-p-SiO{sub 2} nano-composite coating possesses less porosity than that in Ni-P coating, resulting in improving corrosion resistance.

  16. Magnetocaloric effect and corrosion resistance of La(Fe, Si)13 composite plates bonded by different fraction of phenolic resin

    Science.gov (United States)

    Zhang, K. S.; Xue, J. N.; Wang, Y. X.; Sun, H.; Long, Y.

    2018-04-01

    La(Fe, Si)13-based composite plates were successfully fabricated using different amount of phenolic resin. The introduction of phenolic resin as binder increased the corrosion resistance and maintained giant magnetocaloric effect for La(Fe, Si)13-based composite plates. It was found that corroded spots were firstly observed on the boundaries between resin and La(Fe, Si)13 particles, rather than in La(Fe, Si)13-based particles, after being immersed in static distilled water. The corrosion rate decreased significantly with the increase of resin content. And the increase of the content of phenolic resin leads to the reduction of corrosion current density. Meanwhile, the volumetric magnetic entropy change ΔSM decreases slightly as the content of phenolic resin increases. The ΔSM of the plates with 3 wt.%, 5 wt.% and 8 wt.% resin are 63.1, 61.2 and 59.8 mJ/cm3 K under a low magnetic field change of 1 T, respectively.

  17. Preparation of the CNC/Ag/beeswax composites for enhancing antibacterial and water resistance properties of paper.

    Science.gov (United States)

    Liu, Kai; Liang, Hunan; Nasrallah, Joseph; Chen, Lihui; Huang, Liulian; Ni, Yonghao

    2016-05-20

    An effective method of preparing composites containing inorganic (Ag) and organic (beeswax) particles was established in this study. Ag nanoparticles were first immobilized on the cellulose nanocrystals (CNC) during the reduction of AgNO3 in the presence of CNC, then mixed with beeswax by high speed stirring. Scanning transmission electron microscopy (STEM) images indicated that Ag and beeswax particles were uniformly dispersed and stable in the network structure formed by CNC. Upon coating on a paper surface, a layer of beeswax film was evident based on scanning electron microscopy (SEM) images. The dynamic contact angle and antibacterial activity tests indicated that the contact angle of coated paper reached 113.06° and the growth inhibition of Escherichia coli increased to 99.96%, respectively, at a coating amount of 21.53 g/m(2). When applied onto paper surface by coating, the CNC/Ag/beeswax composites can impact paper with antibacterial property and improved water resistance. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Effects of exercise on insulin resistance and body composition in overweight and obese women with and without polycystic ovary syndrome.

    Science.gov (United States)

    Hutchison, Samantha K; Stepto, Nigel K; Harrison, Cheryce L; Moran, Lisa J; Strauss, Boyd J; Teede, Helena J

    2011-01-01

    Polycystic ovary syndrome (PCOS) is an insulin-resistant (IR) state. Visceral fat (VF) is independently associated with IR. The objectives of the study were to explore mechanisms underpinning IR by assessing the effect of exercise training on IR and body composition in overweight PCOS and non-PCOS women. This was a prospective exercise intervention study. The study was conducted at an academic medical center. Participants included 20 overweight PCOS and 14 overweight non-PCOS women. The intervention included 12 wk of intensified aerobic exercise (3 h/wk). IR on euglycemic hyperinsulinemic clamp, body composition including abdominal visceral and sc fat distribution by computer tomography and lipids was measured. PCOS subjects were more IR (P = 0.02) and had more VF (P = 0.04 age adjusted) than non-PCOS women. In PCOS women, IR correlated with VF (r = -0.78, P cardiometabolic risk factors including IR, triglycerides, and VF in PCOS were observed without significant weight loss and if confirmed in future controlled trials, suggest weight loss should not be the sole focus of exercise programs.

  19. Development of a new composite system: fire resistant and highly structural

    Directory of Open Access Journals (Sweden)

    González, J.

    2010-06-01

    Full Text Available Infrastructure and rail sectors share two singularities in terms of materials: highly structural performance and strict fire requirements. Moreover, there is a common growing interest in both sectors: the use of organic matrix composite materials due to their high performance, lightweight and in-service behavior. Traditionally, fire fillers have been added to the matrix, decreasing its mechanical performance in a critical way. A study about composite materials formed by three different matrices and four different carbon fibers will be presented in this paper. A number of laminates have been manufactured by using these composite materials in order to analyze both the resin processing and the compatibility of the different matrices and fibers. This study is a need due to the fact that these matrices are fire-related and therefore further problems may arise in comparison with standard matrices.

    Los sectores de la construcción y del ferrocarril tienen dos aspectos en común en el ámbito de los materiales: la utilización de materiales altamente estructurales y la aplicación de estrictos requerimientos de fuego. Asimismo, en ambos sectores existe un interés creciente en el uso de materiales compuestos de matriz orgánica por sus excelentes prestaciones, ligereza y comportamiento en servicio. Tradicionalmente, se han aplicado cargas anti-fuego a la matriz orgánica, disminuyendo sus propiedades mecánicas de forma importante. En este artículo se presentará un estudio de materiales compuestos formados por tres matrices orgánicas diferentes y cuatro tipos de fibras de carbono. Con estos constituyentes se han fabricado diferentes laminados para analizar, por un lado, la procesabilidad de estas resinas, y, por otro, la compatibilidad de estas resinas con las fibras de refuerzo utilizadas. Este estudio es necesario debido a que al tratarse de resinas formuladas con características frente a fuego y humos, su fabricabilidad puede

  20. Resistance scaling for composite fermions in the presence of a density gradient

    International Nuclear Information System (INIS)

    Stormer, H. L.; Tsui, Daniel Chee; Pan, Wei; West, Ken W.; Baldwin, K. W.; Pfeiffer, Loren N.

    2006-01-01

    The magnetoresistance, R xx , at even-denominator fractional fillings, of an ultra high quality two-dimensional electron system at T ∼ 35 mK is observed to be strictly linear in magnetic field, B. While at 35 mK R xx is dominated by the integer and fractional quantum Hall states, at T ≅ 1.2 K an almost perfect linear relationship between R xx and B emerges over the whole magnetic field range except for spikes at the integer quantum Hall states. This linear R xx cannot be understood within the Composite Fermion model, but can be explained through the existence of a density gradient in our sample

  1. High-temperature Corrosion Resistance of Composite Coating Prepared by Micro-arc Oxidation Combined with Pack Cementation Aluminizing

    Directory of Open Access Journals (Sweden)

    HUANG Zu-jiang

    2018-01-01

    Full Text Available Al2O3 ceramic film was obtained by micro-arc oxidation (MAO process on Al/C103 specimen, which was prepared by pack cementation aluminizing technology on C103 niobium alloy. With the aid of XRD and SEM equipped with EDS, chemical compositions and microstructures of the composite coatings before and after high-temperature corrosion were analyzed. The behavior and mechanism of the composite coatings in high-temperature oxidation and hot corrosion were also investigated. The results indicate that oxidation mass gain at 1000℃ for 10h of the Al/C103 specimen is 6.98mg/cm2, and it is 2.89mg/cm2 of the MAO/Al/C103 specimen. However, the mass gain of MAO/Al/C103 specimen (57.52mg/cm2 is higher than that of Al/C103 specimen (28.08mg/cm2 after oxidation 20h. After hot corrosion in 75%Na2SO4 and 25%NaCl at 900℃ for 50h, the mass gain of Al/C103 and MAO/Al/C103 specimens are 70.54mg/cm2 and 55.71mg/cm2 respectively, Al2O3 and perovskite NaNbO3 phases are formed on the surface; the diffusion of molten salt is suppressed, due to part of NaNbO3 accumulated in the MAO micropores. Therefore, MAO/Al/C103 specimen exhibits better hot corrosion resistance.

  2. Direct contact thermoelectric generator (DCTEG): A concept for removing the contact resistance between thermoelectric modules and heat source

    International Nuclear Information System (INIS)

    Kim, Tae Young; Negash, Assmelash; Cho, Gyubaek

    2017-01-01

    Highlights: • A design concept of a direct contact thermoelectric generator (DCTEG) is proposed. • Power generation characteristics of the DCTEG on a diesel engine are examined. • Maximum power output of ∼45 W and conversion efficiency of ∼2.0% are obtained. • Effect of clearance on energy conversion of the DCTEG is numerically investigated. • A 132% increase in output power with a flush mounted configuration is obtained. - Abstract: This paper proposes the concept of a direct contact thermoelectric generator (DCTEG) to enhance the practicality and widen the application areas of thermoelectric generators (TEGs). In the DCTEG, one thermoelectric module (TEM) surface is directly exposed to a heat source, and the other surface is in direct contact with a coolant flow. The current direct-contact configuration is beneficial for system fabrication, maintenance, long-term reliability, and maximizing energy usage in cooperation with other energy systems because of its simple configuration and lack of interfaces between the TEMs and heat sources. In order to validate the proposed concept experimentally, a DCTEG was constructed by fabricating customized TEMs and exhaust gas and coolant channels with openings to mount the TEMs. A diesel engine served as a heat source by providing hot exhaust gas into the DCTEG, while the coolant (water–ethylene glycol mixture) was pumped into the coolant channels to remove heat. Based on the experimental results obtained under various engine operating conditions, the power generation of the DCTEG was characterized in the form of current–voltage and power–voltage curves. The maximum output power of 43 W and conversion efficiency of 2.0% were obtained under the highest engine load and rotation speed conditions. A series of numerical simulations was carried out to investigate the effect of the system configuration on the DCTEG power generation performance with the clearance between the TEM surfaces and exhaust gas

  3. Tribaloy intermetallic alloy compositions: new materials or additives for wear resistant applications

    International Nuclear Information System (INIS)

    Cameron, C.B.; Hoffman, R.A.; Poskitt, R.W.

    1975-01-01

    Properties and uses of TRIBALOY alloys in powder metallurgy fabrication are discussed. Powders of TRIBALOY can be blended with essentially any powder processed by powder metallurgy. Green strength of the blended powder parts is reduced as the amount of TRIBALOY is increased. The concentration of TRIBALOY, however, is usually 15 to 20 volume percent, a compromise between green strength and effectiveness as a wear resistant part. Blended powders are sintered at the temperature normally used for the base metal with special consideration given to a low dew point in the atmosphere. The sintered parts can be coined, carburized, machined, or impregnated in any of the well-known ways. TRIBALOY as a powder blending agent has extended the useful life of P/M parts by factors of 5 and more. A variety of industries are presently using P/M parts at higher temperatures, heavier loads, in poorer or non-lubricated conditions or at higher speeds because of the addition of TRIBALOY. More important, however, is that TRIBALOY can be incorporated in parts to be made by powder metallurgy which until now had not been feasible. The overall effect has been considerable savings for the customer by switching to the powder metal method of manufacturing and increased activity for the fabricator

  4. Resistência adesiva de resinas compostas à dentina Adhesive strength between composite resin and dentin substract

    Directory of Open Access Journals (Sweden)

    Joel BIANCHI

    1999-01-01

    Full Text Available As pesquisas relacionadas com adesão à dentina, em virtude da ampla aplicabilidade, são de grande interesse para a Odontologia. O objetivo deste estudo foi avaliar, através de ensaios de tração, a resistência adesiva ao substrato dentinário, em função de dois sistemas adesivos (3M e Kerr, dois níveis de rugosidade do substrato dentinário (lixas 220 e 600, duas áreas de colagem (3,14 mm2 - 12,56 mm2, e duas condições de armazenagem (inicial e final. A análise dos resultados evidenciou que: 1 houve diferença estatisticamente significativa entre os dois sistemas adesivos, sendo que o da Kerr apresentou os valores mais elevados de resistência adesiva; 2 diferenças significativas não ficaram evidentes na resistência da adesão entre os dois níveis de rugosidade dentinária; 3 as colagens em áreas menores apresentaram, em nível altamente significativo, maior resistência adesiva; 4 a condição de armazenagem influiu nos resultados dependendo da área e do sistema adesivo.There is a wealthy literature on bonding strength of composites to dentine. One of the reasons for the large number of studies is the continuous introduction of new bonding agents in combination with accumulated knowledge about the dentine substrate conditions. The aim of the present study was to compare the "in vitro" tensile bond strengths of two dentine bonding systems (3M and Kerr applied to different dentine roughness (220 and 600 gritand two sizes of bonding areas (3,14 mm2 and 12,56 mm2. Different storage conditions (initial and final were also considered. One hundred and sixty human teeth were randomly allocated in 4 groups. The Kerr system groups and the smallest bonding area groups showed the highest tensile strengths. The storage condition and the substrate roughness did not display a significant influence on bond strengths.

  5. Wear-resistant EBW coatings based on a TiB{sub 2}-Fe SHS composite with a high-alloy matrix

    Energy Technology Data Exchange (ETDEWEB)

    Galchenko, Nina K.; Kolesnikova, Ksenia A.; Belyuk, Sergei I. [Institute of Strength Physics and Materials Science SB RAS, Tomsk (Russian Federation); Semenov, Grigoriy V., E-mail: Kolesnikova_KsAl@mail.ru [Tomsky Instrument Manufacturing Company, Tomsk (Russian Federation)

    2011-07-01

    In the work, we studied the structure and properties of “titanium diboride – high-chromium cast iron binder” coatings obtained by electron beam welding. It is demonstrated that the phase and structure formation of the composite coatings depends on the content of high-chromium cast iron in the deposited mixture. Varying the volume fraction of the hardening compounds and the chemical composition of the metal binder makes possible wear-resistant coatings with specified operating characteristics. Key words: electron beam technology, composite coatings.

  6. Connective Heating Improvement for Emergency Fire Shelters (CHIEFS): Composition and Performance of Fire Shelter Concepts at Close-Out

    Science.gov (United States)

    Fody, Joshua M.; Daryabeigi, Kamran; Bruce, Walter E., III; Wells, John M.; Wusk, Mary E.; Calomino, Anthony M.; Miller, Steve D.

    2018-01-01

    Summary of highlights of the Convective Heating Improvement for Emergency Fire Shelters (CHIEFS) taskunder NASA. CHIEFS was tasked with providing the US Forest Service with an emergency fire shelter forimproved resistance to flame contact. Emphasis is on the final shelter designs at task close-out (end of FY17).

  7. Fracture resistance of endodontically treated teeth restored with short fiber composite used as a core material-An in vitro study.

    Science.gov (United States)

    Garlapati, Tejesh Gupta; Krithikadatta, Jogikalmat; Natanasabapathy, Velmurugan

    2017-10-01

    This in-vitro study tested the fracture resistance of endodontically treated molars with Mesial-Occluso-Distal (MOD) cavities restored with fibre reinforced composite material everX posterior in comparision with hybrid composite and ribbond fiber composite. Fifty intact freshly extracted human mandibular first molars were collected and were randomly divided into five groups (n=10). Group 1: positive control (PC) intact teeth without any endodontic preparation. In groups 2 through 6 after endodontic procedure standard MOD cavities were prepared and restored with their respective core materials as follows: group 2, negative control (NC) left unrestored or temporary flling was applied. Group 3, Hybrid composite (HC) as a core material (Te-Econom Plus Ivoclar Vivadent Asia) group 4, Ribbond (Ribbond; Seattle, WA, USA)+conventional composite resin (RCR) group 5, everX posterior (everX Posterior GC EUROPE)+conventional composite resin (EXP) after thermocycling fracture resistance for the samples were tested using universal testing machine. The results were analysed using ANOVA and Tukey's HSD post hoc tests. Mean fracture resistance (in Newton, N) was group 1: 1568.4±221.71N, group 2: 891.0±50.107N, group 3: 1418.3±168.71N, group 4:1716.7±199.51N and group 5: 1994.8±254.195N. Among the materials tested, endodontically treated teeth restored with everX posterior fiber reinforced composite showed superior fracture resistance. Copyright © 2017 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  8. Employing Concept Mapping as a Pre-Writing Strategy to Help EFL Learners Better Generate Argumentative Compositions

    Science.gov (United States)

    Al-Shaer, Ibrahim M. R.

    2014-01-01

    The purpose of this research was to examine the impact of employing concept mapping at a pre-writing stage on English as a foreign language (EFL) students' ability to generate better argumentative essays. Thirty-eight participants were randomly assigned to two groups participating in Writing II course at Al-Quds Open University (QOU). Both groups…

  9. D-aspartic acid supplementation combined with 28 days of heavy resistance training has no effect on body composition, muscle strength, and serum hormones associated with the hypothalamo-pituitary-gonadal axis in resistance-trained men.

    Science.gov (United States)

    Willoughby, Darryn S; Leutholtz, Brian

    2013-10-01

    It was hypothesized that D-aspartic acid (D-ASP) supplementation would not increase endogenous testosterone levels or improve muscular performance associated with resistance training. Therefore, body composition, muscle strength, and serum hormone levels associated with the hypothalamo-pituitary-gonadal axis were studied after 28 days of resistance training and D-ASP supplementation. Resistance-trained men resistance trained 4 times/wk for 28 days while orally ingesting either 3 g of placebo or 3 g of D-ASP. Data were analyzed with 2 × 2 analysis of variance (P aspartate oxidase (DDO) were determined. Body composition and muscle strength were significantly increased in both groups in response to resistance training (P .05). Total and free testosterone, luteinizing hormone, gonadotropin-releasing hormone, and estradiol were unchanged with resistance training and D-ASP supplementation (P > .05). For serum D-ASP and DDO, D-ASP resulted in a slight increase compared with baseline levels (P > .05). For the D-ASP group, the levels of serum DDO were significantly increased compared with placebo (P < .05). The gonadal hormones were unaffected by 28 days of D-ASP supplementation and not associated with the observed increases in muscle strength and mass. Therefore, at the dose provided, D-ASP supplementation is ineffective in up-regulating the activity of the hypothalamo-pituitary-gonadal axis and has no anabolic or ergogenic effects in skeletal muscle. © 2013 Elsevier Inc. All rights reserved.

  10. Redox Control of Aphid Resistance through Altered Cell Wall Composition and Nutritional Quality.

    Science.gov (United States)

    Rasool, Brwa; McGowan, Jack; Pastok, Daria; Marcus, Sue E; Morris, Jenny A; Verrall, Susan R; Hedley, Peter E; Hancock, Robert D; Foyer, Christine H

    2017-09-01

    The mechanisms underpinning plant perception of phloem-feeding insects, particularly aphids, remain poorly characterized. Therefore, the role of apoplastic redox state in controlling aphid infestation was explored using transgenic tobacco ( Nicotiana tabacum ) plants that have either high (PAO) or low (TAO) ascorbate oxidase (AO) activities relative to the wild type. Only a small number of leaf transcripts and metabolites were changed in response to genotype, and cell wall composition was largely unaffected. Aphid fecundity was decreased significantly in TAO plants compared with other lines. Leaf sugar levels were increased and maximum extractable AO activities were decreased in response to aphids in all genotypes. Transcripts encoding the Respiratory Burst Oxidase Homolog F, signaling components involved in ethylene and other hormone-mediated pathways, photosynthetic electron transport components, sugar, amino acid, and cell wall metabolism, were increased significantly in the TAO plants in response to aphid perception relative to other lines. The levels of galactosylated xyloglucan were decreased significantly in response to aphid feeding in all the lines, the effect being the least in the TAO plants. Similarly, all lines exhibited increases in tightly bound (1→4)-β-galactan. Taken together, these findings identify AO-dependent mechanisms that limit aphid infestation. © 2017 American Society of Plant Biologists. All Rights Reserved.

  11. Pressure resistance of copper benzene-1,3,5-tricarboxylate - carbon aerogel composites

    Science.gov (United States)

    Domán, Andrea; Nagy, Balázs; Nichele, Laura P.; Srankó, Dávid; Madarász, János; László, Krisztina

    2018-03-01

    The protective effect of a resorcinol - formaldehyde based carbon aerogel (CA) support was compared in two different forms of the hybrid made of copper benzene-1,3,5-tricarboxilate (HKUST-1) and CA. HKUST-1:CA with identical mass ratio (1:1). HKUST-1+CAis a physical mixture while in HKUST-1@CA the metal organic framework (MOF) crystals were grown on CA under solvothermal conditions. The effect of water vapour and the external pressure (25-200 bar) was investigated. TG/DTG data show that the prehistory of the samples has a strong influence on their thermal behaviour and nitrogen data suggest that part of the MOF grows in the wider pores of the HKUST-1@CA sample. Although there are no dramatic differences in the water adsorption isotherms, the physical mixture is slightly more proficient. In dry samples under compression the crystalline structure of the free HKUST-1 is well conserved. The nanoscale structure of the hybrids is sensitive to applied pressure and formation of mesopores of wide size distribution occurs. No significant difference was found between the corresponding CH4 adsorption isotherms of the composite samples, either in the as-prepared samples or after compression at 100 bar. After being exposed to high external pressure the CH4 uptake seems to be governed by the MOF.

  12. Fatigue resistance, debonding force, and failure type of fiber-reinforced composite, polyethylene ribbon-reinforced, and braided stainless steel wire lingual retainers in vitro

    NARCIS (Netherlands)

    Foek, Dave Lie Sam; Yetkiner, Enver; Ozcan, Mutlu

    Objective: To analyze the fatigue resistance, debonding force, and failure type of fiber-reinforced composite, polyethylene ribbon-reinforced, and braided stainless steel wire lingual retainers in vitro. Methods: Roots of human mandibular central incisors were covered with silicone, mimicking the

  13. Mechanical property characterization and impact resistance of selected graphite/PEEK composite materials

    Science.gov (United States)

    Baker, Donald J.

    1994-01-01

    To use graphite polyetheretherketone (PEEK) material on highly curved surfaces requires that the material be drapable and easily conformable to the surface. This paper presents the mechanical property characterization and impact resistance results for laminates made from two types of graphite/PEEK materials that will conform to a curved surface. These laminates were made from two different material forms. These forms are: (1) a fabric where each yarn is a co-mingled Celion G30-500 3K graphite fiber and PEEK thermoplastic fiber; and (2) an interleaved material of Celion G30-500 3K graphite fabric interleaved with PEEK thermoplastic film. The experimental results from the fabric laminates are compared with results for laminates made from AS4/PEEK unidirectional tape. The results indicate that the tension and compression moduli for quasi-isotropic and orthotropic laminates made from fabric materials are at least 79 percent of the modulus of equivalent laminates made from tape material. The strength of fabric material laminates is at least 80 percent of laminates made from tape material. The evaluation of fabric material for shear stiffness indicates that a tape material laminate could be replaced by a fabric material laminate and still maintain 89 percent of the shear stiffness of the tape material laminate. The notched quasi-isotropic compression panel failure strength is 42 to 46 percent of the unnotched quasi-isotropic laminate strength. Damage area after impact with 20 ft-lbs of impact energy is larger for the co-mingled panels than for the interleaved panels. The inerleaved panels have less damage than panels made from tape material. Residual compression strength of quasi-isotropic panels after impact of 20 ft-lbs of energy varies between 33 percent of the undamaged quasi-isotropic material strength for the tape material and 38 percent of the undamaged quasi-isotropic material strength for the co-mingled fabric material.

  14. Composite piping: basic materials, manufacturing methods, hydrolysis resistance. Bibliographical data and state of the art; Tuyauteries composites: materiaux de base, methodes de fabrication, resistance a l`hydrolyse. Donnees bibliographiques et etat de l`art

    Energy Technology Data Exchange (ETDEWEB)

    Pays, M.F.

    1997-10-01

    EDF has decided to replace traditional materials by glass reinforced plastic for the manufacture of certain PWR water piping. However, these are liable to in-service degradation through the hydrolysis of the operating conditions which can involve mechanical stresses or specific temperature and humidity conditions. These resins have been the subject of bibliographical surveys and laboratory experiments providing the following main results: the water diffusion in the selected thermoset resins (polyester, vinyl-ester, epoxy) can reach one percent in weight, according to the relative humidity and temperature; the water absorption is a reversible phenomenon, at the beginning and is followed by hydrolysis, an irreversible deterioration affecting the chemical functions of the polymeric chain. Thermally activated, the reaction limits the temperature for the use of these resins; polyester resins are made of a large number of ester bonds and are highly sensitive to hydrolysis. These resins can be classified on the basis of the alcohol and acid which they come acid. A possible hydrolytic degradation does not prevent from using these resins in humid environments. The cooling towers in Belleville, Nogent ad Chooz are equipped with water collecting channels made of polyester laminates which have behaved satisfactorily since their installation in 1982. In acid environments, even concentrated, resins have a better behavior than in a neutral medium. However, they can be liable to stress corrosion. Polyester resins ar not suitable for use in concentrated base media. Vinyl-ester resins are more appropriate for this purpose, although their resistance will be lower than in a neutral environment. When resins are used as a matrix for composites, the presence of glass fibers modifies their behavior. The physico-chemical protection of the fiber/matrix interfaces and of the surface of the glass itself through the sizing of the fibers plays key role in the durability of the composites, which

  15. Development of the composition of chocolate mass that resistant to bloom

    Directory of Open Access Journals (Sweden)

    M. E. Tkeshelashvili

    2017-01-01

    Full Text Available Chocolate or used as a coating on the surface of the sweets chocolate mass when exposed to a temperature drop and/or a drop in the humidity of the environment, change color, lose gloss and acquire an unwanted grayish-white surface. The loss of the appearance of chocolate – the effect of bloom is the reason for the return of products from the trading network causing highly tangible the economic damage to the producers. In this connection, experimental researches devoted to the problem of preventing bloom and developing consist of chocolate masses preclusion to bloom appear to be an urgent task. The purpose of the research is develop consist of chocolate and covering chocolate resistant to bloom. The work is performed at the Scientific research institute of «Applied research of innovative technologies and food quality» of Plekhanov Russian University of Economics. For an investigation, samples of chocolate and covering chocolate based on cocoa butter were made in the formulation of which an additive including milk fat/isomalt/polydextrose. The control samples were dark chocolate and covering chocolate prepared according to a unified formula. For the formation of blooming, the samples were exposed to temperature fluctuations and relative humidity. The measurement of the color of chocolate is implementation by an instrumental method based on the analysis of the optical characteristics of the product. The coefficients of reflection spectra of samples of chocolate were converted into color coordinates of space CIEL ? a ? b* 1976. The emergence of a bloom of chocolate by changing the parameter lightness L ? (CIEL ? a ? b* was diagnosed. The effect of introducing an additive, including milk fat/isomalt/polydextrose on fat and sugar bloom, was determined in the formulation of chocolate masses. Based on research the consist of the chocolate mass has been developed which practically does not change the taste of the finished chocolate products

  16. High-temperature fracture and fatigue resistance of a ductile β-TiNb reinforced γ-TiAl intermetallic composite

    International Nuclear Information System (INIS)

    Rao, K.T.V.; Ritchie, R.O.

    1998-01-01

    The high-temperature fatigue-crack propagation and fracture resistance of a model γ-TiAl intermetallic composite reinforced with 20 vol. % ductile β-TiNb particles is examined at elevated temperatures of 650 and 800 C and compared with behavior at room temperature. TiNb reinforcements are found to enhance the fracture toughness of γ-TiAl, even at high temperatures, from about 123 to ∼40 MPa m 1/2 , although their effectiveness is lower compared to room temperature due to the reduction in strength of TiNb particles. Under monotonic loading, crack-growth response in the composite is characterized by resistance-curve behavior arising from crack trapping, renucleation and resultant crack bridging effects attributable to the presence of TiNb particles. In addition, crack-tip blunting associated with plasticity increases the crack-initiation (matrix) toughness of the composite, particularly at 800 C, above the ductile-to-brittle transition temperature (DBTT) for γ-TiAl. High-temperature fatigue-crack growth resistance, however, is marginally degraded by the addition of TiNb particles in the C-R (edge) orientation, similar to observations made at room temperature; premature fatigue failure of TiNb ligaments in the crack wake diminishes the role of bridging under cyclic loading. Both fatigue and fracture resistance of the composite are slightly lower at 650 C (just below the DBTT for TiAl) compared to the behavior at ambient and 800 C. Overall, the beneficial effect of adding ductile TiNb reinforcements to enhance the room-temperature fracture and fatigue resistance of γ-TiAl alloys is retained up to 800 C, in air environments. There is concern, however, regarding the long-term environmental stability of these composite microstructures in unprotected atmospheres

  17. Associations of Low-Intensity Resistance Training with Body Composition and Lipid Profile in Obese Patients with Type 2 Diabetes.

    Science.gov (United States)

    Hamasaki, Hidetaka; Kawashima, Yu; Tamada, Yoshiki; Furuta, Masashi; Katsuyama, Hisayuki; Sako, Akahito; Yanai, Hidekatsu

    2015-01-01

    Resistance training to increase muscle mass and functional capacity is an integral part of diet and exercise programs for the management of obesity and type 2 diabetes. Low-intensity resistance training with slow movement and tonic force generation (LST) may be a practical and safe regimen for elderly obese individuals but the health benefits are uncertain. This study investigated the effects of LST on body composition and metabolic parameters in obese patients with type 2 diabetes. Twenty-six obese patients with type 2 diabetes engaged in LST training during hospitalization and were advised to maintain this regimen for 12 weeks after discharge. We compared lipid profile, arterial stiffness, and body composition before and after LST training. After 12 weeks of LST training, the ratio of lower extremity muscle mass to body weight increased significantly (0.176 ± 0.028 to 0.184 ± 0.023, mean ± SD), while body fat mass and body fat percentage decreased significantly (36.2 ± 10.9 kg to 34.3 ± 9.4 kg and 41.2 ± 8.6% to 40.1 ± 7.7%, respectively). Moreover, high-density lipoprotein cholesterol was significantly increased (42.2 ± 14 mg/dl to 46.3 ± 12.4 mg/dl) and both free fatty acids and lipoprotein(a) were decreased (665.2 ± 212.1 μEq/l to 525.4 ± 231.3 μEq/l and 15.4 ± 18 mg/dl to 13.8 ± 18 mg/dl, respectively). No significant change was observed in arterial stiffness. Although this study was a non-controlled investigation and some confounding factors including dietary intake, medication and compliance with training might affect the study result, a brief (12-week) LST training program may be a safe and effective strategy for the management of obesity and type 2 diabetes.

  18. Associations of Low-Intensity Resistance Training with Body Composition and Lipid Profile in Obese Patients with Type 2 Diabetes.

    Directory of Open Access Journals (Sweden)

    Hidetaka Hamasaki

    Full Text Available Resistance training to increase muscle mass and functional capacity is an integral part of diet and exercise programs for the management of obesity and type 2 diabetes. Low-intensity resistance training with slow movement and tonic force generation (LST may be a practical and safe regimen for elderly obese individuals but the health benefits are uncertain. This study investigated the effects of LST on body composition and metabolic parameters in obese patients with type 2 diabetes. Twenty-six obese patients with type 2 diabetes engaged in LST training during hospitalization and were advised to maintain this regimen for 12 weeks after discharge. We compared lipid profile, arterial stiffness, and body composition before and after LST training. After 12 weeks of LST training, the ratio of lower extremity muscle mass to body weight increased significantly (0.176 ± 0.028 to 0.184 ± 0.023, mean ± SD, while body fat mass and body fat percentage decreased significantly (36.2 ± 10.9 kg to 34.3 ± 9.4 kg and 41.2 ± 8.6% to 40.1 ± 7.7%, respectively. Moreover, high-density lipoprotein cholesterol was significantly increased (42.2 ± 14 mg/dl to 46.3 ± 12.4 mg/dl and both free fatty acids and lipoprotein(a were decreased (665.2 ± 212.1 μEq/l to 525.4 ± 231.3 μEq/l and 15.4 ± 18 mg/dl to 13.8 ± 18 mg/dl, respectively. No significant change was observed in arterial stiffness. Although this study was a non-controlled investigation and some confounding factors including dietary intake, medication and compliance with training might affect the study result, a brief (12-week LST training program may be a safe and effective strategy for the management of obesity and type 2 diabetes.

  19. Resistance mutations and CTL epitopes in archived HIV-1 DNA of patients on antiviral treatment: toward a new concept of vaccine.

    Directory of Open Access Journals (Sweden)

    Jennifer Papuchon

    Full Text Available Eleven patients responding successfully to first-line antiretroviral therapy (ART were investigated for proviral drug resistance mutations (DRMs in RT by ultra-deep pyrosequencing (UDPS. After molecular typing of the class I alleles A and B, the CTL epitopes in the Gag, Nef and Pol regions of the provirus were sequenced and compared to the reference HXB2 HIV-1 epitopes. They were then matched with the HLA alleles with determination of theoretical affinity (TA. For 3 patients, the results could be compared with an RNA sample of the circulating virus at initiation of therapy. Five out of 11 patients exhibited DRMs by UDPS. The issue is whether a therapeutic switch is relevant in these patients by taking into account the identity of the archived resistance mutations. When the archived CTL epitopes were determined on the basis of the HLA alleles, different patterns were observed. Some epitopes were identical to those reported for the reference with the same TA, while others were mutated with a decrease in TA. In 2 cases, an epitope was observed as a combination of subpopulations at entry and was retrieved as a single population with lower TA at success. With regard to immunological stimulation and given the variability of the archived CTL epitopes, we propose a new concept of curative vaccine based on identification of HIV-1 CTL epitopes after prior sequencing of proviral DNA and matching with HLA class I alleles.

  20. Negative differential resistance and rectification effects in zigzag graphene nanoribbon heterojunctions: Induced by edge oxidation and symmetry concept

    Science.gov (United States)

    Nazirfakhr, Maryam; Shahhoseini, Ali

    2018-03-01

    By applying non-equilibrium Green's functions (NEGF) in combination with tight-binding (TB) model, we investigate and compare the electronic transport properties of H-terminated zigzag graphene nanoribbon (H/ZGNR) and O-terminated ZGNR/H-terminated ZGNR (O/ZGNR-H/ZGNR) heterostructure under finite bias. Moreover, the effect of width and symmetry on the electronic transport properties of both models is also considered. The results reveal that asymmetric H/ZGNRs have linear I-V characteristics in whole bias range, but symmetric H-ZGNRs show negative differential resistance (NDR) behavior which is inversely proportional to the width of the H/ZGNR. It is also shown that the I-V characteristic of O/ZGNR-H/ZGNR heterostructure shows a rectification effect, whether the geometrical structure is symmetric or asymmetric. The fewer the number of zigzag chains, the bigger the rectification ratio. It should be mentioned that, the rectification ratios of symmetric heterostructures are much bigger than asymmetric one. Transmission spectrum, density of states (DOS), molecular projected self-consistent Hamiltonian (MPSH) and molecular eigenstates are analyzed subsequently to understand the electronic transport properties of these ZGNR devices. Our findings could be used in developing nanoscale rectifiers and NDR devices.

  1. The effect of 8 weeks of Circuit Resistance Training on metabolic syndrome risk factors and body composition in women over age 50 with diabetes mellitus type 2

    Directory of Open Access Journals (Sweden)

    Seyede Amene Azarmehr

    2017-10-01

    Full Text Available Abstract Introduction: The prevalence of type 2 diabetes mellitus (T2DM increased significantly in the last three decades, and effective strategies to manage and prevent this disease are urgently needed. Physical activity and exercise training is an effective way for metabolic syndrome risk factors in type 2 diabetes mellitus (T2DM patients. However, the effects of Circuit Resistance Training (CRT program on patients T2DM are unknown. The purpose of this study is to investigation the effect of 8 weeks of Circuit resistance training (CRT on metabolic syndrome and body composition in women over age 50 with T2DM. Methods: Twenty women over 50 years old with diabetes Referred to diabetes Center of 17 Shahrivar hospital in Amol and they were divided randomly into two groups; Circuit resistance (n=10 and Control (n=10. Resistance training consisted of 10 stations for 8 weeks and 3 sessions per week (Intensity 60-80% 1RM. Levels of Lipid profile and body composition before and after eight weeks training in both groups were measured. Statistical analysis of the data was carried out by SPSS (v. 22. Results Fasting Blood Sugar (FBS levels (P=0.021, Triglycerides (0.010, high-density lipoprotein cholesterol (0.042, significant decreased in CRT. Also after 8 weeks circuit resistance training, BMI (P= 0.003, WHR (P=0.004 and body fat present (0.019 significant decreased in CRT. Conclusion: According to our results, CRT was an effective approach to improve the Anthropometrics, FBS, lipid profile in women over age 50 with diabetes mellitus type 2. Moreover, CRT did have influence on LDL level.  Keywords: Circuit resistance training, insulin resistance, metabolic syndrome, body composition

  2. Elastic/plastic analyses of advanced composites investigating the use of the compliant layer concept in reducing residual stresses resulting from processing

    Science.gov (United States)

    Arnold, Steven M.; Arya, Vinod K.; Melis, Matthew E.

    1990-01-01

    High residual stresses within intermetallic and metal matrix composite systems can develop upon cooling from the processing temperature to room temperature due to the coefficient of thermal expansion (CTE) mismatch between the fiber and matrix. As a result, within certain composite systems, radial, circumferential, and/or longitudinal cracks have been observed to form at the fiber-matrix interface. The compliant layer concept (insertion of a compensating interface material between the fiber and matrix) was proposed to reduce or eliminate the residual stress buildup during cooling and thus minimize cracking. The viability of the proposed compliant layer concept is investigated both elastically and elastoplastically. A detailed parametric study was conducted using a unit cell model consisting of three concentric cylinders to determine the required character (i.e., thickness and material properties) of the compliant layer as well as its applicability. The unknown compliant layer mechanical properties were expressed as ratios of the corresponding temperature dependent Ti-24Al-11Nb (a/o) matrix properties. The fiber properties taken were those corresponding to SCS-6 (SiC). Results indicate that the compliant layer can be used to reduce, if not eliminate, radial and circumferential residual stresses within the fiber and matrix and therefore also reduce or eliminate the radial cracking. However, with this decrease in in-plane stresses, one obtains an increase in longitudinal stress, thus potentially initiating longitudinal cracking. Guidelines are given for the selection of a specific compliant material, given a perfectly bonded system.

  3. Influence of temperature and composition in the mechanical resistance and porosity of ceramic pieces

    Directory of Open Access Journals (Sweden)

    Jordán Vidal, M. M.

    2001-03-01

    Full Text Available We have tried to establish a relationship between the raw material and the mechanical properties of ceramic pieces subjected to different firing processes, so under the determinant of the thermal process we have done a follow up on the petrogenetic process that the manufacture of ceramics represents. This is evaluated in terms of the mechanical behaviour of the ceramic tile bodies, which have been normalised and submitted to tests for flexion. The principal objective is to be able to indicate what the optimum firing temperature for each sample is, and to determine what it is in the ceramic body which offers the greatest resistance when a specific force is applied. The study of the texture of the ceramic body will be considered mainly in relation to the existent porosity, as well as its distribution, which conditions its characteristics and specifications. The relation between porosity and the parameters that describe the porous texture of the ceramic tile pieces studied is complicated because of the fact that these have many pores with a complex and irregular spatial disposition, with a broad distribution of forms and sizes, and as such they do not fit into established empirical equations.

    Se ha tratado de establecer la relación entre materia prima y propiedades mecánicas de piezas cerámicas sometidas a procesos de cocción diversos. Bajo el condicionante del proceso térmico se realiza un seguimiento del proceso petrogenético que representa la fabricación cerámica y se evalúa a través del comportamiento mecánico de probetas cerámicas normalizadas y sometidas a ensayos de flexión. El objetivo principal es poder indicar cuál es la temperatura óptima de cocción para cada muestra y determinar cuál es aquélla en que la probeta cerámica ofrece una mayor resistencia al aplicarle una determinada carga. El estudio de la textura de la matriz cerámica es de gran interés en relación con la porosidad, asi como su distribuci

  4. Skin conductance biofeedback training in adults with drug-resistant temporal lobe epilepsy and stress-triggered seizures: a proof-of-concept study.

    Science.gov (United States)

    Micoulaud-Franchi, Jean-Arthur; Kotwas, Iliana; Lanteaume, Laura; Berthet, Christelle; Bastien, Mireille; Vion-Dury, Jean; McGonigal, Aileen; Bartolomei, Fabrice

    2014-12-01

    The present proof-of-concept study investigated the feasibility of skin conductance biofeedback training in reducing seizures in adults with drug-resistant temporal lobe epilepsy (TLE), whose seizures are triggered by stress. Skin conductance biofeedback aims to increase levels of peripheral sympathetic arousal in order to reduce cortical excitability. This might seem somewhat counterintuitive, since such autonomic arousal may also be associated with increased stress and anxiety. Thus, this sought to verify that patients with TLE and stress-triggered seizures are not worsened in terms of stress, anxiety, and negative emotional response to this nonpharmacological treatment. Eleven patients with drug-resistant TLE with seizures triggered by stress were treated with 12 sessions of biofeedback. Patients did not worsen on cognitive evaluation of attentional biases towards negative emotional stimuli (P>.05) or on psychometric evaluation with state anxiety inventory (P = .059); in addition, a significant improvement was found in the Negative Affect Schedule (P = .014) and in the Beck Depression Inventory (P = .009). Biofeedback training significantly reduced seizure frequency with a mean reduction of -48.61% (SD = 27.79) (P = .005). There was a correlation between the mean change in skin conductance activity over the biofeedback treatment and the reduction of seizure frequency (r(11) = .62, P = .042). Thus, the skin conductance biofeedback used in the present study, which teaches patients to achieve an increased level of peripheral sympathetic arousal, was a well-tolerated nonpharmacological treatment. Further, well-controlled studies are needed to confirm the therapeutic value of this nonpharmacological treatment in reducing seizures in adults with drug-resistant TLE with seizures triggered by stress. Copyright © 2014 Elsevier Inc. All rights reserved.

  5. New concept of 3D printed bone clip (polylactic acid/hydroxyapatite/silk composite) for internal fixation of bone fractures.

    Science.gov (United States)

    Yeon, Yeung Kyu; Park, Hae Sang; Lee, Jung Min; Lee, Ji Seung; Lee, Young Jin; Sultan, Md Tipu; Seo, Ye Bin; Lee, Ok Joo; Kim, Soon Hee; Park, Chan Hum

    Open reduction with internal fixation is commonly used for the treatment of bone fractures. However, postoperative infection associated with internal fixation devices (intramedullary nails, plates, and screws) remains a significant complication, and it is technically difficult to fix multiple fragmented bony fractures using internal fixation devices. In addition, drilling in the bone to install devices can lead to secondary fracture, bone necrosis associated with postoperative infection. In this study, we developed bone clip type internal fixation device using three- dimensional (3D) printing technology. Standard 3D model of the bone clip was generated based on computed tomography (CT) scan of the femur in the rat. Polylacticacid (PLA), hydroxyapatite (HA), and silk were used for bone clip material. The purpose of this study was to characterize 3D printed PLA, PLA/HA, and PLA/HA/Silk composite bone clip and evaluate the feasibility of these bone clips as an internal fixation device. Based on the results, PLA/HA/Silk composite bone clip showed similar mechanical property, and superior biocompatibility compared to other types of the bone clip. PLA/HA/Silk composite bone clip demonstrated excellent alignment of the bony segments across the femur fracture site with well-positioned bone clip in an animal study. Our 3D printed bone clips have several advantages: (1) relatively noninvasive (drilling in the bone is not necessary), (2) patient-specific design (3) mechanically stable device, and (4) it provides high biocompatibility. Therefore, we suggest that our 3D printed PLA/HA/Silk composite bone clip is a possible internal fixation device.

  6. Metagenomic analysis of bacterial community composition and antibiotic resistance genes in a wastewater treatment plant and its receiving surface water.

    Science.gov (United States)

    Tang, Junying; Bu, Yuanqing; Zhang, Xu-Xiang; Huang, Kailong; He, Xiwei; Ye, Lin; Shan, Zhengjun; Ren, Hongqiang

    2016-10-01

    The presence of pathogenic bacteria and the dissemination of antibiotic resistance genes (ARGs) may pose big risks to the rivers that receive the effluent from municipal wastewater treatment plants (WWTPs). In this study, we investigated the changes of bacterial community and ARGs along treatment processes of one WWTP, and examined the effects of the effluent discharge on the bacterial community and ARGs in the receiving river. Pyrosequencing was applied to reveal bacterial community composition including potential bacterial pathogen, and Illumina high-throughput sequencing was used for profiling ARGs. The results showed that the WWTP had good removal efficiency on potential pathogenic bacteria (especially Arcobacter butzleri) and ARGs. Moreover, the bacterial communities of downstream and upstream of the river showed no significant difference. However, the increase in the abundance of potential pathogens and ARGs at effluent outfall was observed, indicating that WWTP effluent might contribute to the dissemination of potential pathogenic bacteria and ARGs in the receiving river. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. Microstructure and Wear Resistance of Composite Coating by Laser Cladding Al/TiN on the Ti-6Al-4V Substrate

    Science.gov (United States)

    Zhang, H. X.; Yu, H. J.; Chen, C. Z.

    2015-05-01

    The composite coatings were fabricated by laser cladding Al/TiN pre-placed powders on Ti-6Al-4V substrate for enhancing wear resistance and hardness of the substrate. The composite coatings were analyzed by means of X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The sliding wear tests were performed by MM200 wear test machine. The hardness of the coatings was tested by HV-1000 hardness tester. After laser cladding, it was found that there was a good metallurgical bond between the coating and the substrate. The composite coatings were mainly composed of the matrix of β-Ti (Al) and the reinforcements of titanium nitride (TiN), Ti3Al, TiAl and Al3Ti. The hardness and wear resistance of the coatings on four samples were greatly improved, among which sample 4 exhibited the highest hardness and best wear resistance. The hardness of the coating on sample 4 was approximately 2.5 times of the Ti-6Al-4V substrate. And the wear resistance of sample 4 was four times of the substrate.

  8. Ductile-reinforcement toughening in γ-TiAl intermetallic-matrix composites: Effects on fracture toughness and fatigue-crack propagation resistance

    International Nuclear Information System (INIS)

    Venkateswara Rao, K.T.; Ritchie, R.O.; Odette, G.R.

    1994-01-01

    The influence of the type, volume fraction, thickness and orientation of ductile phase reinforcements on the room temperature fatigue and fracture resistance of γ-TiAl intermetallic alloys is investigated. Large improvements in toughness compared to monolithic γ-TiAl are observed in both the TiNb- and Nb-reinforced composites under monotonic loading. Toughness increases with increasing ductile phase content, reinforcement thickness and strength; orientation effect are minimal. Crack-growth behavior is characterized by steep resistance curves primarily due to crack trapping/renucleation and extensive crack bridging by the ductile-phase particles. In contrast, under cyclic loading the influence of ductile phases on fatigue resistance is strongly dependent upon reinforcement orientation. Compared to monolithic γ-TiAl, improvements in fatigue-crack growth resistance are observed in TiNb-reinforced composites only in the face (C-L) orientation; crack-growth rates for the edge (C-R) orientation are actually faster in the composite. In comparison, Nb-particle reinforcements offer less toughening under monotonic loading but enhance the fatigue properties compared to TiNb reinforcements under cyclic loading

  9. Characterization of the radiation resistance of ITER-relevant and innovative fiber composites for the ITER magnet system

    International Nuclear Information System (INIS)

    Bittner-Rohrhofer, K.

    2003-06-01

    The application of glass-fiber reinforced composites for the insulation of the superconducting magnet coils of the ITER (International Thermonuclear Experimental Reactor ) fusion device requires high material performance. The mechanical integrity of the insulation is influenced by the neutron- and g-environment and by the high mechanical stresses of the magnet system over the entire plant lifetime of 20 years. Materials suggested as insulation have to be investigated in extensive test programs with respect to the present ITER design criteria. In particular, the ultimate tensile strength as well as the interlaminar shear behavior will change under static and dynamic load (tension-tension fatigue) at 77 K after irradiation to the ITER design fluence level of 1x1022 m-2 (E620.1 MeV). Therefore, a frequency of 10 Hz and a ratio of 0.1 were chosen, in order to simulate the pulsed TOKAMAK-operation as closely as possible. Furthermore, the fatigue behavior of the material is investigated over more than 3x104 cycles, which is the ITER- relevant design fatigue limit. Basically, these insulation systems are based on combined glass-fiber/Kapton tapes, which are impregnated with di-functional DGEBA epoxy resins. Several mechanical investigations showed that the radiation resistance of these organic resins is dramatically affected by radiation at a neutron fluence of 1x1022 m-2 (E620.1 MeV). Moreover, the material strength after irradiation is strongly influenced by these factors: the winding direction of the tapes, the quality of fabrication and the drastic delamination process of the whole compound. Furthermore, the radiation induced damage of adhesives applied for supporting the interfacial bonding between the glass-fiber tape and Kapton has an adverse effect on the material performance. In addition, the poor interlaminar shear behavior does not fulfil the requirements of ITER. These test-results motivated for the development of innovative resin systems with higher stability

  10. High performance corrosion and wear resistant composite titanium nitride layers produced on the AZ91D magnesium alloy by a hybrid method

    Directory of Open Access Journals (Sweden)

    Michał Tacikowski

    2014-09-01

    Full Text Available Composite, diffusive titanium nitride layers formed on a titanium and aluminum sub-layer were produced on the AZ91D magnesium alloy. The layers were obtained using a hybrid method which combined the PVD processes with the final sealing by a hydrothermal treatment. The microstructure, resistance to corrosion, mechanical damage, and frictional wear of the layers were examined. The properties of the AZ91D alloy covered with these layers were compared with those of the untreated alloy and of some engineering materials such as 316L stainless steel, 100Cr6 bearing steel, and the AZ91D alloy subjected to commercial anodizing. It has been found that the composite diffusive nitride layer produced on the AZ91D alloy and then sealed by the hydrothermal treatment ensures the corrosion resistance comparable with that of 316L stainless steel. The layers are characterized by higher electrochemical durability which is due to the surface being overbuilt with the titanium oxides formed, as shown by the XPS examinations, from titanium nitride during the hydrothermal treatment. The composite titanium nitride layers exhibit high resistance to mechanical damage and wear, including frictional wear which is comparable with that of 100Cr6 bearing steel. The performance properties of the AZ91D magnesium alloy covered with the composite titanium nitride coating are substantially superior to those of the alloy subjected to commercial anodizing which is the dominant technique employed in industrial practice.

  11. A Comparative Study of the Microstructure, Mechanical Properties and Corrosion Resistance of Ni- or Fe- Based Composite Coatings by Laser Cladding

    Science.gov (United States)

    Wan, M. Q.; Shi, J.; Lei, L.; Cui, Z. Y.; Wang, H. L.; Wang, X.

    2018-04-01

    Ni- and Fe-based composite coatings were laser cladded on 40Cr steel to improve the surface mechanical property and corrosion resistance, respectively. The microstructure and phase composition were analyzed by x-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) equipped with an energy-dispersive spectrometer (EDS). The micro-hardness, tribological properties and electrochemical corrosion behavior of the coatings were evaluated. The results show that the thickness of both the coatings is around 0.7 mm, the Ni-based coating is mainly composed of γ-(Ni, Fe), FeNi3, Ni31Si12, Ni3B, CrB and Cr7C3, and the Fe-based coating is mainly composed of austenite and (Fe, Cr)7C3. Micro-hardness of the Ni-based composite coating is about 960 HV0.3, much higher than that of Fe-based coating (357.4 HV0.3) and the 40Cr substrate (251 HV0.3). Meanwhile, the Ni-based composite coating possesses better wear resistance than the Fe-based coating validated by the worn appearance and the wear loss. Electrochemical results suggested that Ni-based coating exhibited better corrosion resistance than the Fe-based coating. The 40Cr substrate could be well protected by the Ni-based coating.

  12. Anisotropy of the thermal conductivity and electrical resistivity of the SiC/Si biomorphic composite based on a white-eucalyptus biocarbon template

    Science.gov (United States)

    Parfen'eva, L. S.; Orlova, T. S.; Smirnov, B. I.; Smirnov, I. A.; Misiorek, H.; Mucha, J.; Jezowski, A.; de Arellano-Lopez, A. R.; Martinez-Fernandez, J.; Varela-Feria, F. M.

    2006-12-01

    The thermal conductivity κ and electrical resistivity ρ of a cellular ecoceramic, namely, the SiC/Si biomorphic composite, are measured in the temperature range 5 300 K. The SiC/Si biomorphic composite is fabricated using a cellular biocarbon template prepared from white eucalyptus wood by pyrolysis in an argon atmosphere with subsequent infiltration of molten silicon into empty through cellular channels of the template. The temperature dependences κ(T) and ρ(T) of the 3C-SiC/Si biomorphic composite at a silicon content of ˜30 vol % are measured for samples cut out parallel and perpendicular to the direction of tree growth. Data on the anisotropy of the thermal conductivity κ are presented. The behavior of the dependences κ(T) and ρ(T) of the SiC/Si biomorphic composite at different silicon contents is discussed in terms of the results obtained and data available in the literature.

  13. Effect of aerobic training and resistance training on circulating irisin level and their association with change of body composition in overweight/obese adults: a pilot study.

    Science.gov (United States)

    Kim, H-J; Lee, H-J; So, B; Son, J S; Yoon, D; Song, W

    2016-06-20

    The novel myokine irisin has been reported as a therapeutic target for metabolic disease. The objective of this study is to reveal the effects of aerobic training (AT) and resistance training (RT) on circulating irisin levels and their associations with change of body composition in overweight/obese adults. Twenty eight overweight/obese adults (BMI>23 kg/m(2)) were included in this study and compared before and after 8 weeks of exercise program (60 min/day, 5 times in a week). The subjects, in both aerobic and resistance training, showed significant improvement in anthropometric parameters and exercise capacities including maximal oxygen uptake and muscle strength. Interestingly, the circulating irisin was significantly increased in resistance training group (p=0.002) but not in aerobic training (p=0.426) compared to control group. In addition, we found the positive correlation between change of the circulating irisin and muscle mass (r=0.432, p=0.022) and the negative correlation between change of the circulating irisin and fat mass (r=-0.407, p=0.031). In the present pilot study, we found that circulating irisin level was increased by 8 weeks of resistance training in overweight/obese adults, suggesting that resistance training could be the efficient exercise type in overweight/obese considering positive change of body composition concomitant with increase of irisin levels.

  14. Comparisons of low-intensity versus moderate-intensity combined aerobic and resistance training on body composition, muscle strength, and functional performance in older women.

    Science.gov (United States)

    Shiotsu, Yoko; Yanagita, Masahiko

    2018-06-01

    This study aimed to examine the effects of exercise order of combined aerobic and low- or moderate-intensity resistance training into the same session on body composition, functional performance, and muscle strength in healthy older women. Furthermore, this study compared the effects of different (low- vs moderate-) intensity combined training. A total of 60 healthy older women (age 61-81 y) were randomly assigned to five groups that performed aerobic exercise before low-intensity resistance training (AR-L, n = 12) or after resistance training (RA-L, n = 12), performed aerobic exercise before moderate-intensity resistance training (AR-M, n = 12) or after resistance training (RA-M, n = 12), or nonintervention control conditions (CON, n = 12). Body composition, functional performance, and muscle strength were evaluated before and after the 10-week training. No effects of exercise order of combined aerobic and low- or moderate-intensity resistance training (AR-L vs RA-L, AR-M vs RA-M) were observed in body composition, functional performance, or muscle strength, whereas the effects of training intensity of combined training (AR-L vs AR-M, RA-L vs RA-M) were observed on functional performance. All combined trainings significantly increased muscle strength and gait ability (P Functional reach test significantly increased in the AR-M and RA-M groups (P training increases muscle strength and improves gait ability, regardless of the exercise order. Also, greater improvement in dynamic balance capacity, a risk factor associated with falling, is observed in moderate-intensity combined training.

  15. Heavy Resistance Training and Supplementation With the Alleged Testosterone Booster Nmda has No Effect on Body Composition, Muscle Performance, and Serum Hormones Associated With the Hypothalamo-Pituitary-Gonadal Axis in Resistance-Trained Males

    Directory of Open Access Journals (Sweden)

    Darryn S. Willoughby

    2014-03-01

    Full Text Available The effects of 28 days of heavy resistance training while ingesting the alleged testosterone-boosting supplement, NMDA, were determined on body composition, muscle strength, serum cortisol, prolactin, and hormones associated with the hypothalamo-pituitary- gonadal (HPG axis. Twenty resistance-trained males engaged in 28 days of resistance training 4 times/wk while orally ingesting daily either 1.78 g of placebo (PLAC or NMDA. Data were analyzed with separate 2 x 2 ANOVA (p 0.05 or supplementation (p > 0.05. In regard to total body mass and fat-free mass, however, each was significantly increased in both groups in response to resistance training (p 0.05. In both groups, lower-body muscle strength was significantly increased in response to resistance training (p 0.05. All serum hormones (total and free testosterone, LH, GnRH, estradiol, cortisol, prolactin were unaffected by resistance training (p > 0.05 or supplementation (p > 0.05. The gonadal hormones and cortisol and prolactin were unaffected by 28 days of NMDA supplementation and not associated with the observed increases in muscle strength and mass. At the dose provided, NMDA had no effect on HPG axis activity or ergogenic effects in skeletal muscle.

  16. Influence of load and sliding velocity on wear resistance of solid-lubricant composites of ultra-high molecular weight polyethylene

    Science.gov (United States)

    Panin, S. V.; Kornienko, L. A.; Buslovich, D. G.; Alexenko, V. O.; Ivanova, L. R.

    2017-12-01

    To determine the limits of the operation loading intervals appropriate for the use of solid lubricant UHMWPE composites in tribounits for mechanical engineering and medicine, the tribotechnical properties of UHMWPE blends with the optimum solid lubricant filler content (polytetrafluoroethylene, calcium stearate, molybdenum disulfide, colloidal graphite, boron nitride) are studied under dry sliding friction at different velocities (V = 0.3 and 0.5 m/s) and loads (P = 60 and 140 N). It is shown that the wear resistance of solid lubricant UHMWPE composites at moderate sliding velocities (V = 0.3 m/s) and loads (P = 60 N) increases 2-3 times in comparison with pure UHMWPE, while at high load P = 140 N wear resistance of both neat UHMWPE and its composites is reduced almost twice. At high sliding velocities and loads (up to P = 140 N), multiple increasing of the wear of pure UHMWPE and its composites takes place (by the factor of 5 to 10). The operational conditions of UHMWPE composites in tribounits in engineering and medicine are discussed.

  17. MICROSTRUCTURE AND WEAR RESISTANCE OF COMPOSITE COATING BY LASER CLADDING Al/TiN ON THE Ti–6Al–4V SUBSTRATE

    OpenAIRE

    H. X. ZHANG; H. J. YU; C. Z. CHEN

    2015-01-01

    The composite coatings were fabricated by laser cladding Al/TiN pre-placed powders on Ti–6Al–4V substrate for enhancing wear resistance and hardness of the substrate. The composite coatings were analyzed by means of X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The sliding wear tests were performed by MM200 wear test machine. The hardness of the coatings was tested by HV-1000 hardness tester. After laser cladding, it was found that there...

  18. Advanced composites structural concepts and materials technologies for primary aircraft structures. Structural response and failure analysis: ISPAN modules users manual

    Science.gov (United States)

    Hairr, John W.; Huang, Jui-Ten; Ingram, J. Edward; Shah, Bharat M.

    1992-01-01

    The ISPAN Program (Interactive Stiffened Panel Analysis) is an interactive design tool that is intended to provide a means of performing simple and self contained preliminary analysis of aircraft primary structures made of composite materials. The program combines a series of modules with the finite element code DIAL as its backbone. Four ISPAN Modules were developed and are documented. These include: (1) flat stiffened panel; (2) curved stiffened panel; (3) flat tubular panel; and (4) curved geodesic panel. Users are instructed to input geometric and material properties, load information and types of analysis (linear, bifurcation buckling, or post-buckling) interactively. The program utilizing this information will generate finite element mesh and perform analysis. The output in the form of summary tables of stress or margins of safety, contour plots of loads or stress, and deflected shape plots may be generalized and used to evaluate specific design.

  19. THE CONCEPT OF USING EVOLUTIONARY ALGORITHMS AS TOOLS FOR OPTIMAL PLANNING OF MULTIMODAL COMPOSITION IN THE DIDACTIC TEXTS

    Directory of Open Access Journals (Sweden)

    Marek A. Jakubowski

    2014-11-01

    Full Text Available At the beginning we would like to provide a short description of the new theory of learning in the digital age called connectivism. It is the integration of principles explored by the following theories: chaos, network, complexity and self-organization. Next, we describe in short new visual solutions for the teaching of writing so called multimodal literacy 5–11. We define and describe the following notions: multimodal text and original theory so called NOS (non-optimum systems methodology as a basis for new methods of visual solutions at the classes and audiovisual texts applications. Especially, we would like to emphasize the tremendous usefulness of evolutionary algorithms VEGA and NSGA as tools for optimal planning of multimodal composition in teaching texts. Finally, we give some examples of didactic texts for classrooms, which provide a deep insight into learning skills and tasks needed in the Internet age.

  20. Multi-layer concept for containments in an integrated construction method by using steel composite building block modules

    International Nuclear Information System (INIS)

    Friedrich, F.

    1987-01-01

    Containments consisting of steel modules have been developed as an alternative design and solution to the double shell containments comprising two separate structures. The combination of different reinforcement layers of steel plates and round reinforcing bars in one cross section provides a high loadbearing capacity. The multiple utilization of the steel plates in the composite section as formwork in the construction state and as reinforcement and liner in the operation or damage/failure states, respectively, yields a number of advantages. The main effect is being achieved due to the high degree of prefabrication and completion (finishing) of the steel modules and the reduction of expenditure on the job site connected with same. (orig.)

  1. Mathematical modeling of (13)C label incorporation of the TCA cycle: the concept of composite precursor function.

    Science.gov (United States)

    Uffmann, Kai; Gruetter, Rolf

    2007-11-15

    A novel approach for the mathematical modeling of (13)C label incorporation into amino acids via the TCA cycle that eliminates the explicit calculation of the labeling of the TCA cycle intermediates is described, resulting in one differential equation per measurable time course of labeled amino acid. The equations demonstrate that both glutamate C4 and C3 labeling depend in a predictable manner on both transmitochondrial exchange rate, V(X), and TCA cycle rate, V(TCA). For example, glutamate C4 labeling alone does not provide any information on either V(X) or V(TCA) but rather a composite "flux". Interestingly, glutamate C3 simultaneously receives label not only from pyruvate C3 but also from glutamate C4, described by composite precursor functions that depend in a probabilistic way on the ratio of V(X) to V(TCA): An initial rate of labeling of glutamate C3 (or C2) being close to zero is indicative of a high V(X)/V(TCA). The derived analytical solution of these equations shows that, when the labeling of the precursor pool pyruvate reaches steady state quickly compared with the turnover rate of the measured amino acids, instantaneous labeling can be assumed for pyruvate. The derived analytical solution has acceptable errors compared with experimental uncertainty, thus obviating precise knowledge on the labeling kinetics of the precursor. In conclusion, a substantial reformulation of the modeling of label flow via the TCA cycle turnover into the amino acids is presented in the current study. This approach allows one to determine metabolic rates by fitting explicit mathematical functions to measured time courses.

  2. Analysis of thin-walled cylindrical composite shell structures subject to axial and bending loads: Concept development, analytical modeling and experimental verification

    Science.gov (United States)

    Mahadev, Sthanu

    Continued research and development efforts devoted in recent years have generated novel avenues towards the advancement of efficient and effective, slender laminated fiber-reinforced composite members. Numerous studies have focused on the modeling and response characterization of composite structures with particular relevance to thin-walled cylindrical composite shells. This class of shell configurations is being actively explored to fully determine their mechanical efficacy as primary aerospace structural members. The proposed research is targeted towards formulating a composite shell theory based prognosis methodology that entails an elaborate analysis and investigation of thin-walled cylindrical shell type laminated composite configurations that are highly desirable in increasing number of mechanical and aerospace applications. The prime motivation to adopt this theory arises from its superior ability to generate simple yet viable closed-form analytical solution procedure to numerous geometrically intense, inherent curvature possessing composite structures. This analytical evaluative routine offers to acquire a first-hand insight on the primary mechanical characteristics that essentially govern the behavior of slender composite shells under typical static loading conditions. Current work exposes the robustness of this mathematical framework via demonstrating its potential towards the prediction of structural properties such as axial stiffness and bending stiffness respectively. Longitudinal ply-stress computations are investigated upon deriving the global stiffness matrix model for composite cylindrical tubes with circular cross-sections. Additionally, this work employs a finite element based numerical technique to substantiate the analytical results reported for cylindrically shaped circular composite tubes. Furthermore, this concept development is extended to the study of thin-walled, open cross-sectioned, curved laminated shells that are geometrically

  3. The Cryogenic Impact Resistant Evaluation of Composite Materials for Use in Composite Pressure Vessels with an Additional Cryogenic Bonding Scope, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The intent of the proposed effort is to investigate the detailed composite material performance characteristics after being subjected to cryogenic temperatures and...

  4. Impact of body composition parameters on clinical outcomes in patients with metastatic castrate-resistant prostate cancer treated with docetaxel.

    Science.gov (United States)

    Cushen, Samantha J; Power, Derek G; Murphy, Kevin P; McDermott, Ray; Griffin, Brendan T; Lim, Marvin; Daly, Louise; MacEneaney, Peter; O' Sullivan, Kathleen; Prado, Carla M; Ryan, Aoife M

    2016-06-01

    Body composition may influence clinical outcomes of certain chemotherapeutic agents. We examined the prognostic significance of skeletal muscle mass and adipose tissue on docetaxel toxicity and overall survival in patients with metastatic castrate resistant prostate cancer (mCRPC). A retrospective review of patients medical records with mCRPC, treated with docetaxel was conducted. Body composition parameters (skeletal muscle mass, muscle attenuation [MA], visceral and subcutaneous adipose tissue) were measured at L3 by computed tomography (CT) and defined using previously established cut points. Toxicity profile was assessed after 3 cycles of the drug and graded according to the National Cancer Institute Common Toxicity Criteria (version 4). Overall survival was analysed. Overall 63 patients, mean age 69 years (SD 8.3), were included. Sarcopenia was present in 47% (n = 30) and of these 26.7% (8/30) were sarcopenic obese. Common toxicities (all grades) observed included fatigue (80.9%), pain (46%), and constipation (34.9%). DLT occurred in 22 (34.9%) patients; of these 10 patients (15.8%) experienced dose reductions and 12 patients (19%) experienced dose terminations. Measurements of adiposity were not predictive of DLT, however 59.1% patients who had a combination of both sarcopenia and low MA experienced DLT compared to 29.3% of patients without sarcopenia and low MA (p = 0.021). Skeletal muscle index and MA were significantly lower in patients who experienced neutropenia (grade I-II) (46.5 cm 2 /m 2 vs. 51.2 cm 2 /m 2 , p = 0.005) compared to their counterparts (24.6 HU vs. 32.2 HU, p = 0.044). Neither sarcopenia nor sarcopenic obesity was associated with overall survival. In multivariate analysis, BMI ≥25 kg/m 2 (HR: 0.349, CI: 0.156-0.782, p = 0.010) was a significant predictor of longer overall survival and both visceral fat index ≥ median 58.7 cm 2 /m 2 (HR: 2.266 CI: 1.066-4.814, p = 0.033) and anaemia (HR: 2.81, CI: 1.297-6.091, p

  5. Aging-Resistant Functionalized LDH⁻SAS/Nitrile-Butadiene Rubber Composites: Preparation and Study of Aging Kinetics/Anti-Aging Mechanism.

    Science.gov (United States)

    Li, Tianxiang; Shi, Zhengren; He, Xianru; Jiang, Ping; Lu, Xiaobin; Zhang, Rui; Wang, Xin

    2018-05-18

    With the aim of improving the anti-aging properties of nitrile-butadiene rubber (NBR), a functional organic filler, namely LDH⁻SAS, prepared by intercalating 4-amino-benzenesulfonic acid monosodium salt (SAS) into layered double hydroxides (LDHs) through anion exchange, was added to nitrile-butadiene rubber (NBR), giving the NBR/LDH⁻SAS composites. Successful preparation of LDH⁻SAS was confirmed by XRD, TGA and FTIR. LDH⁻SAS was well dispersed in the NBR matrix, owing to its strong interaction with the nitrile group of NBR. The obtained NBR/LDH⁻SAS composites exhibited excellent thermo-oxidative aging resistance as shown by TGA-DSC. Further investigation by ATR-FTIR indicated that SAS can capture the radical groups, even during the aging process, which largely accounts for the improved aging resistance.

  6. Aging-Resistant Functionalized LDH–SAS/Nitrile-Butadiene Rubber Composites: Preparation and Study of Aging Kinetics/Anti-Aging Mechanism

    Science.gov (United States)

    Li, Tianxiang; Shi, Zhengren; He, Xianru; Jiang, Ping; Lu, Xiaobin; Zhang, Rui

    2018-01-01

    With the aim of improving the anti-aging properties of nitrile-butadiene rubber (NBR), a functional organic filler, namely LDH–SAS, prepared by intercalating 4-amino-benzenesulfonic acid monosodium salt (SAS) into layered double hydroxides (LDHs) through anion exchange, was added to nitrile-butadiene rubber (NBR), giving the NBR/LDH–SAS composites. Successful preparation of LDH–SAS was confirmed by XRD, TGA and FTIR. LDH–SAS was well dispersed in the NBR matrix, owing to its strong interaction with the nitrile group of NBR. The obtained NBR/LDH–SAS composites exhibited excellent thermo-oxidative aging resistance as shown by TGA-DSC. Further investigation by ATR-FTIR indicated that SAS can capture the radical groups, even during the aging process, which largely accounts for the improved aging resistance. PMID:29783656

  7. TiFeCoNi oxide thin film - A new composition with extremely low electrical resistivity at room temperature

    International Nuclear Information System (INIS)

    Yang, Ya-Chu; Tsau, Chun-Huei; Yeh, Jien-Wei

    2011-01-01

    We show the electrical resistivity of a TiFeCoNi oxide thin film. The electrical resistivity of the TiFeCoNi thin film decreased sharply after a suitable period of oxidation at high temperature. The lowest resistivity of the TiFeCoNi oxide film was 35 ± 3 μΩ-cm. The low electrical resistivity of the TiFeCoNi oxide thin film was attributed to Ti, which is more reactive than the other elements, reacting with oxygen at the initial stage of annealing. The low resistivity is caused by the remaining electrons.

  8. Fatigue resistance and crack propensity of novel "super-closed" sandwich composite resin restorations in large MOD defects.

    Science.gov (United States)

    Magne, Pascal; Silva, Silvana; Andrada, Mauro de; Maia, Hamilton

    2016-01-01

    To assess the influence of conventional glass ionomer cement (GIC) vs resin-modified GIC (RMGIC) as a base material for novel, super-closed sandwich restorations (SCSR) and its effect on shrinkage-induced crack propensity and in vitro accelerated fatigue resistance. A standardized MOD slottype tooth preparation was applied to 30 extracted maxillary molars (5 mm depth/5 mm buccolingual width). A modified sandwich restoration was used, in which the enamel/dentin bonding agent was applied first (Optibond FL, Kerr), followed by a Ketac Molar (3M ESPE)(group KM, n = 15) or Fuji II LC (GC) (group FJ, n = 15) base, leaving 2 mm for composite resin material (Miris 2, Coltène-Whaledent). Shrinkageinduced enamel cracks were tracked with photography and transillumination. Samples were loaded until fracture or to a maximum of 185,000 cycles under isometric chewing (5 H z), starting with a load of 200 N (5,000 X), followed by stages of 400, 600, 800, 1,000, 1,200, and 1,400 N at a maximum of 30,000 X each. Groups were compared using the life table survival analysis (α = .008, Bonferroni method). Group FJ showed the highest survival rate (40% intact specimens) but did not differ from group KM (20%) or traditional direct restorations (13%, previous data). SCSR generated less shrinkage-induced cracks. Most failures were re-restorable (above the cementoenamel junction [CEJ]). Inclusion of GIC/RMGIC bases under large direct SCSRs does not affect their fatigue strength but tends to decrease the shrinkage-induced crack propensity. The use of GIC/ RMGIC bases and the SCSR is an easy way to minimize polymerization shrinkage stress in large MOD defects without weakening the restoration.

  9. Application of manure containing tetracyclines slowed down the dissipation of tet resistance genes and caused changes in the composition of soil bacteria.

    Science.gov (United States)

    Xiong, Wenguang; Wang, Mei; Dai, Jinjun; Sun, Yongxue; Zeng, Zhenling

    2018-01-01

    Manure application contributes to the increased environmental burden of antibiotic resistance genes (ARGs). We investigated the response of tetracycline (tet) resistance genes and bacterial taxa to manure application amended with tetracyclines over two months. Representative tetracyclines (oxytetracycline, chlorotetracycline and doxycycline), tet resistance genes (tet(M), tet(O), tet(W), tet(S), tet(Q) and tet(X)) and bacterial taxa in the untreated soil, +manure, and +manure+tetracyclines groups were analyzed. The abundances of all tet resistance genes in the +manure group were significantly higher than those in the untreated soil group on day 1. The abundances of all tet resistance genes (except tet(Q) and tet(X)) were significantly lower in the +manure group than those in the +manure+tetracyclines group on day 30 and 60. The dissipation rates were higher in the +manure group than those in the +manure+tetracyclines group. Disturbance of soil bacterial community composition imposed by tetracyclines was also observed. The results indicated that tetracyclines slowed down the dissipation of tet resistance genes in arable soil after manure application. Application of manure amended with tetracyclines may provide a significant selective advantage for species affiliated to the taxonomical families of Micromonosporaceae, Propionibacteriaceae, Streptomycetaceae, Nitrospiraceae and Clostridiaceae. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Development of advanced material composites for use as internal insulation for LH2 tanks (gas layer concept)

    Science.gov (United States)

    Gille, J. P.

    1972-01-01

    A program is described that was conducted to develop an internal insulation system for potential application to the liquid hydrogen tanks of a reusable booster, where the tanks would be subjected to repeated high temperatures. The design of the internal insulation is based on a unique gas layer concept, in which capillary or surface tension effects are used to maintain a stable gas layer, within a cellular core structure, between the tank wall and the contained liquid hydrogen. Specific objectives were to select materials for insulation systems that would be compatible with wall temperatures of 350 F and 650 F during reentry into the earth's atmosphere, and to fabricate and test insulation systems under conditions simulating the operating environment. A materials test program was conducted to evaluate the properties of candidate materials at elevated temperatures and at the temperature of liquid hydrogen, and to determine the compatibility of the materials with a hydrogen atmosphere at the appropriate elevated temperature. The materials that were finally selected included Kapton polyimide films, silicone adhesives, fiber glass batting, and in the case of the 350 F system, Teflon film.

  11. Properties and performance of polysiloxane-derived ceramic matrix in heat resistant composites reinforced with R-glass or fine ceramic fibres

    Czech Academy of Sciences Publication Activity Database

    Černý, Martin; Glogar, Petr; Sucharda, Zbyněk; Machovič, V.

    2005-01-01

    Roč. 49, č. 3 (2005), s. 145-152 ISSN 0862-5468 R&D Projects: GA ČR(CZ) GA106/02/0177; GA ČR(CZ) GP106/02/P025 Institutional research plan: CEZ:AV0Z30460519 Keywords : polysiloxane resin * fibre-reinforced composite * mechanical properties Subject RIV: JH - Ceramic s, Fire-Resistant Materials and Glass Impact factor: 0.463, year: 2005

  12. Effect of adhesive luting on the fracture resistance of zirconia compared to that of composite resin and lithium disilicate glass ceramic

    Directory of Open Access Journals (Sweden)

    Myung-Jin Lim

    2017-02-01

    Full Text Available Objectives The purpose of this study was to evaluate the effect of adhesive luting on the fracture resistance of zirconia compared to that of a composite resin and a lithium disilicate glass ceramic. Materials and Methods The specimens (dimension: 2 mm × 2 mm × 25 mm of the composite resin, lithium disilicate glass ceramic, and yttria-stabilized tetragonal zirconia polycrystal (Y-TZP were prepared. These were then divided into nine groups: three non-luting groups, three non-adhesive luting groups, and three adhesive luting groups, for each restorative material. In the non-luting groups, specimens were placed on the bovine tooth without any luting agents. In the non-adhesive luting groups, only zinc phosphate cement was used for luting the specimen to the bovine tooth. In the adhesive luting groups, specimens were pretreated, and the adhesive luting procedure was performed using a self-adhesive resin cement. For all the groups, a flexural test was performed using universal testing machine, in which the fracture resistance was measured by recording the force at which the specimen was fractured. Results The fracture resistance after adhesive luting increased by approximately 29% in the case of the composite resin, 26% in the case of the lithium disilicate glass ceramic, and only 2% in the case of Y-TZP as compared to non-adhesive luting. Conclusions The fracture resistance of Y-TZP did not increased significantly after adhesive luting as compared to that of the composite resin and the lithium disilicate glass ceramic.

  13. Study of the structure and development of the set of reference materials of composition and structure of heat resisting nickel and intermetallic alloys

    Directory of Open Access Journals (Sweden)

    E. B. Chabina

    2016-01-01

    Full Text Available Relevance of research: There are two sizes (several microns and nanodimensional of strengthening j'-phase in single-crystal heat resisting nickel and intermetallic alloys, used for making blades of modern gas turbine engines (GTD. For in-depth study of structural and phase condition of such alloys not only qualitative description of created structure is necessary, but quantitative analysis of alloy components geometrical characteristics. Purpose of the work: Development of reference material sets of heat resisting nickel and intermetallic alloy composition and structure. Research methods: To address the measurement problem of control of structural and geometrical characteristics of single-crystal heat resisting and intermetallic alloys by analytical microscopy and X-ray diffraction analysis the research was carried out using certified measurement techniques on facilities, entered in the Register of Measurement Means of the Russian Federation. The research was carried out on microsections, foils and plates, cut in the plane {100}. Results: It is established that key parameters, defining the properties of these alloys are particle size of strengthening j' -phase, the layer thickness of j-phase between them and parameters of phases lattice. Metrological requirements for reference materials of composition and structure of heat resisting nickel and intermetallic alloys are formulated. The necessary and sufficient reference material set providing the possibility to determine the composition and structure parameters of single-crystal heat resisting nickel and intermetallic alloys is defined. The developed RM sets are certified as in-plant reference materials. Conclusion: The reference materials can be used for graduation of spectral equipment when conducting element analysis of specified class alloys; for calibration of means of measuring alloy structure parameters; for measurement of alloys phases lattice parameters; for structure reference pictures

  14. Modification of a Phenolic Resin with Epoxy- and Methacrylate-Functionalized Silica Sols to Improve the Ablation Resistance of Their Glass Fiber-Reinforced Composites

    Directory of Open Access Journals (Sweden)

    Yu Hu

    2014-01-01

    Full Text Available Functionalized silica sols were obtained by the hydrolytic condensation of (γ-methacryloxypropyltrimethoxysilane (MPMS, (γ-glycidyloxypropyltrimethoxysilane (GPMS and tetraethoxysilane (TEOS. Three different sols were obtained: MPS (derived from MPMS and TEOS, GPS-MPS (derived from GPMS, MPMS and TEOS, and GPSD (derived from GPMS, TEOS and diglycidyl ether of bisphenol A, DGEBA. These silica sols were mixed with a phenolic resin (PR. Ethylenediamine was used as a hardener for epoxy-functionalized sols and benzoyl peroxide was used as an initiator of the free-radical polymerization of methacrylate-functionalized silica sols. Glass fiber-reinforced composites were obtained from the neat PR and MPS-PR, GPS-MPS-PR and GPSD-PR. The resulting composites were evaluated as ablation resistant materials in an acetylene-oxygen flame. A large increase in the ablation resistance was observed when the PR was modified by the functionalized silica sols. The ablation resistance of the composites decreased as follows: GPSD-PR > MPS-PR > GPS-MPS-PR > PR.

  15. Effects of protein supplements consumed with meals, versus between meals, on resistance training-induced body composition changes in adults: a systematic review.

    Science.gov (United States)

    Hudson, Joshua L; Bergia, Robert E; Campbell, Wayne W

    2018-06-01

    The impact of timing the consumption of protein supplements in relation to meals on resistance training-induced changes in body composition has not been evaluated systematically. The aim of this systematic review was to assess the effect of consuming protein supplements with meals, vs between meals, on resistance training-induced body composition changes in adults. Studies published up to 2017 were identified with the PubMed, Scopus, Cochrane, and CINAHL databases. Two researchers independently screened 2077 abstracts for eligible randomized controlled trials of parallel design that prescribed a protein supplement and measured changes in body composition for a period of 6 weeks or more. In total, 34 randomized controlled trials with 59 intervention groups were included and qualitatively assessed. Of the intervention groups designated as consuming protein supplements with meals (n = 16) vs between meals (n = 43), 56% vs 72% showed an increase in body mass, 94% vs 90% showed an increase in lean mass, 87% vs 59% showed a reduction in fat mass, and 100% vs 84% showed an increase in the ratio of lean mass to fat mass over time, respectively. Concurrently with resistance training, consuming protein supplements with meals, rather than between meals, may more effectively promote weight control and reduce fat mass without influencing improvements in lean mass.

  16. Surface modification of carbon/epoxy prepreg using oxygen plasma and its effect on the delamination resistance behavior of carbon/epoxy composites

    International Nuclear Information System (INIS)

    Kim, M.H.; Rhee, K.Y.; Kim, H.J.; Jung, D.H.

    2007-01-01

    It was shown in previous study that the fracture toughness of carbon/epoxy laminated composites could be significantly improved by modifying the surface of the prepreg using Ar + irradiation in an oxygen environment. In this study, the surface of carbon/epoxy prepreg was modified using an oxygen plasma to improve the delamination resistance behavior of carbon/epoxy laminated composites. The variation of the contact angle on the prepreg surface was determined as a function of the modification time, in order to determine the optimal modification time. An XPS analysis was conducted to investigate the chemical changes on the surface of the prepreg caused by the plasma modification. Mode I delamination resistance curves of the composites with and without surface modification were plotted as a function of the delamination increment. The results showed that the contact angle varied from ∼64 o to ∼47 o depending on the modification time and reached a minimum for a modification time of 30 min. The XPS analysis showed that the hydrophilic carbonyl C=O group was formed by the oxygen plasma modification. The results also showed that the delamination resistance behavior was significantly improved by the plasma modification of the prepreg. This improvement was caused by the better layer-to-layer adhesion as well as increased interfacial strength between the fibers and matrix

  17. The Effects of 52 Weeks of Soccer or Resistance Training on Body Composition and Muscle Function in +65-Year-Old Healthy Males – A Randomized Controlled Trial

    Science.gov (United States)

    Andersen, Thomas Rostgaard; Schmidt, Jakob Friis; Pedersen, Mogens Theisen; Krustrup, Peter; Bangsbo, Jens

    2016-01-01

    The effects of 52 weeks of soccer or resistance training were investigated in untrained elderly men. The subjects aged 68.1±2.1 yrs were randomised into a soccer (SG; n = 9), a resistance (RG; n = 9) and a control group (CG; n = 8). The subjects in SG and RG, respectively, trained 1.7±0.3 and 1.8±0.3 times weekly on average during the intervention period. Muscle function and body composition were determined before and after 16 and 52 weeks of the intervention period. In SG, BMI was reduced by 1.5% and 3.0% (psoccer training reduces BMI and improves anti-oxidative capacity, while long-term resistance training impacts muscle protein enzyme expression and increases lean body mass in elderly men. Trial Registration ClinicalTrials.gov: NCT01530035 PMID:26886262

  18. Composition-ratio influence on resistive switching behavior of solution-processed InGaZnO-based thin-film.

    Science.gov (United States)

    Hwang, Yeong-Hyeon; Hwang, Inchan; Cho, Won-Ju

    2014-11-01

    The influence of composition ratio on the bipolar resistive switching behavior of resistive switching memory devices based on amorphous indium-gallium-zinc-oxide (a-IGZO) using the spin-coating process was investigated. To study the stoichiometric effects of the a-IGZO films on device characteristics, four devices with In/Ga/Zn stoichiometries of 1:1:1, 3:1:1, 1:3:1, and 1:1:3 were fabricated and characterized. The 3:1:1 film showed an ohmic behavior and the 1:1:3 film showed a rectifying switching behavior. The current-voltage characteristics of the a-IGZO films with stoichiometries of 1:1:1 and 1:3:1, however, showed a bipolar resistive memory switching behavior. We found that the three-fold increase in the gallium content ratio reduces the reset voltage from -0.9 to - 0.4 V and enhances the current ratio of high to low resistive states from 0.7 x 10(1) to 3 x 10(1). Our results show that the increase in the Ga composition ratio in the a-IGZO-based ReRAM cells effectively improves the device performance and reliability by increasing the initial defect density in the a-IGZO films.

  19. Silane effects on the surface morphology and abrasion resistance of transparent SiO2/UV-curable resin nano-composites

    International Nuclear Information System (INIS)

    Hsiang, Hsing-I.; Chang, Yu-Lun; Chen, Chi-Yu; Yen, Fu-Su

    2011-01-01

    Transparent ultraviolet curable nano-composite coatings consisting of nano-sized SiO 2 and acrylate resin have been developed to improve the abrasion resistance of organic polymers. The nano-sized SiO 2 particles were surface-modified using various amounts of 3-methacryloxypropyltrimethoxysilane. The 3-methacryloxypropyltrimethoxysilane concentration effects on the surface morphology and abrasion resistance of the transparent SiO 2 /ultraviolet-curable resin nano-composites were investigated using scanning electron microscopy, atomic force microscopy, and ultraviolet-visible spectrophotometer. The results showed that as the 3-methacryloxypropyltrimethoxysilane/SiO 2 weight ratio increased from 0.2 to 0.6, the dispersion, compatibility and cross-linking density between the 3-methacryloxypropyltrimethoxysilane-modified SiO 2 particles and acrylate resin were improved, leading to an increase in abrasion resistance. However, as the 3-methacryloxypropyltrimethoxysilane/SiO 2 weight ratio was increased to 1.5, the additional 3-methacryloxypropyltrimethoxysilane may exceed that needed to fill the pores with the probability of SiO 2 nano-particles existing on the coating surface was lower than that for samples with a 3-methacryloxypropyltrimethoxysilane/SiO 2 weight ratio of 0.6. This produced a decrease in abrasion resistance.

  20. Nutritional Modulation of Insulin Resistance

    Directory of Open Access Journals (Sweden)

    Martin O. Weickert

    2012-01-01

    Full Text Available Insulin resistance has been proposed as the strongest single predictor for the development of Type 2 Diabetes (T2DM. Chronic oversupply of energy from food, together with inadequate physical activity, have been recognized as the most relevant factors leading to overweight, abdominal adiposity, insulin resistance, and finally T2DM. Conversely, energy reduced diets almost invariably to facilitate weight loss and reduce abdominal fat mass and insulin resistance. However, sustained weight loss is generally difficult to achieve, and distinct metabolic characteristics in patients with T2DM further compromise success. Therefore, investigating the effects of modulating the macronutrient composition of isoenergetic diets is an interesting concept that may lead to additional important insights. Metabolic effects of various different dietary concepts and strategies have been claimed, but results from randomized controlled studies and particularly from longer-term-controlled interventions in humans are often lacking. However, some of these concepts are supported by recent research, at least in animal models and short-term studies in humans. This paper provides an update of the current literature regarding the role of nutrition in the modulation of insulin resistance, which includes the discussion of weight-loss-independent metabolic effects of commonly used dietary concepts.