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Sample records for affect material properties

  1. Cyclic cryopreservation affects the nanoscale material properties of trabecular bone.

    PubMed

    Landauer, Alexander K; Mondal, Sumona; Yuya, Philip A; Kuxhaus, Laurel

    2014-11-01

    Tissues such as bone are often stored via freezing, or cryopreservation. During an experimental protocol, bone may be frozen and thawed a number of times. For whole bone, the mechanical properties (strength and modulus) do not significantly change throughout five freeze-thaw cycles. Material properties at the trabecular and lamellar scales are distinct from whole bone properties, thus the impact of freeze-thaw cycling at this scale is unknown. To address this, the effect of repeated freezing on viscoelastic material properties of trabecular bone was quantified via dynamic nanoindentation. Vertebrae from five cervine spines (1.5-year-old, male) were semi-randomly assigned, three-to-a-cycle, to 0-10 freeze-thaw cycles. After freeze-thaw cycling, the vertebrae were dissected, prepared and tested. ANOVA (factors cycle, frequency, and donor) on storage modulus, loss modulus, and loss tangent, were conducted. Results revealed significant changes between cycles for all material properties for most cycles, no significant difference across most of the dynamic range, and significant differences between some donors. Regression analysis showed a moderate positive correlation between cycles and material property for loss modulus and loss tangent, and weak negative correlation for storage modulus, all correlations were significant. These results indicate that not only is elasticity unpredictably altered, but also that damping and viscoelasticity tend to increase with additional freeze-thaw cycling. PMID:25278046

  2. Dynamic Material Properties of the Heat-Affected Zone (haz) in Resistance SPOT Welding

    NASA Astrophysics Data System (ADS)

    Ha, Ji-Woong; Song, Jung-Han; Huh, Hoon; Lim, Ji-Ho; Park, Sung-Ho

    This paper is concerned with a methodology to identify the dynamic material properties of the heat-affected zone (HAZ) near the base metal in a resistance spot weld process at various strain rates. In order to obtain the dynamic material properties of the HAZ in the spot-welded steel sheet, specimens are prepared to have similar material properties, hardness and microstructure to the actual HAZ. Such thermally simulated specimens are fabricated with the material thermal cycle simulator (MTCS) and compared with the real one for the hardness and microstructure. Dynamic tensile tests are then conducted with a high speed material testing machine. Stress-strain curves of the thermally simulated HAZ are obtained at various strain rates ranged from 0.001/sec to 100/sec. Obtained material properties are applied to the finite element analysis of the spot-welded tensile-shear specimen in order to verify validity of the proposed testing methodology and obtained results. Analysis results demonstrate that the material properties obtained are appropriate for the FE analysis of spot-welded specimens.

  3. Affects of Microgravity on the Polymerization and Material Properties of Biomedical Grade Polymers

    NASA Astrophysics Data System (ADS)

    Crane, Deborah J.

    2002-01-01

    extended to include other polymers. Polymerization as well as polymer processing in a microgravity environment may affect the length and orientation of the molecular chains, the degree of crosslinking, and distribution of amorphous to crystalline portions of the material, thus changing the ultimate properties of the polymer. Small polymer samples would be produced from the resin for testing and analysis. This research would include the effect of micro-g processing by compression molded vs. ram extruded samples for analysis. Morphological alterations in the material could be monitored using Transmission Electron Microscopy and associated properties such as toughness, density and crystallinity could be determined and compared to terra produced materials using conventional mechanical testing, density gradient columns and calorimetry techniques. If alterations are evident, fatigue testing can be performed on small specimens in order to determine the material's resistance to crack initiation and propagation. number of orthopaedic implant recipients and could be extended for use in robotics and other beneficial applications. Although polymers exhibit the greatest biocompatibility, problems with debris particle generation continue to reduce the effectiveness of UHMWPE as a biomedical material. Further polymer research in a microgravity environment may prove to produce the desired alterations in the materials' morphology and associated properties, therefore providing millions of people with superior orthopaedic implant components and lessen the occurrences of repeat surgery.

  4. Stress analysis of thermally affected rotating nanoshafts with varying material properties

    NASA Astrophysics Data System (ADS)

    Kiani, Keivan

    2016-04-01

    Based on the surface elasticity theory of Gurtin-Murdoch, thermo-elastic fields within rotating nanoshafts with varying material properties subjected to a thermal field are explicitly examined. Accounting for the surface energy effect, the nonclassical boundary conditions are enforced in the cases of fixed-free and free-free conditions. The effects of variation of material properties, temperature of the environment, angular velocity, and radius of the outer radius on the radial displacement, hoop and radial stresses are investigated. In all performed studies, the role of the surface effect on the thermo-elastic field of the nanostructure is methodically discussed.

  5. Acid Rain Affecting the Electrical Properties of Outdoor Composite Dielectric Materials

    NASA Astrophysics Data System (ADS)

    Wang, Xinsheng; Kumagai, Seiji; Yoshimura, Noboru

    1998-12-01

    Acid rain is precipitation with acidity, i.e., pH, below 5.6. There is an increasing interest in the degradation of the electrical properties of outdoor composite dielectric materials under severe contaminant conditions such as acid rain. In this study, the degradation effects of acid rain on the outdoor composite dielectrics are investigated by accelerated aging due to artificial acid rain. Based on the investigation of acid rain, the composition of artificial acid rain is chosen to agree with the actual composition of precipitation. The surface potential, breakdown voltage, tracking resistance, and surface discharge current of dielectric materials are studied. Furthermore, the degradation mechanisms of electrical properties of composite dielectrics are discussed by investigating the degradation of the chemical and physical microstructures of material surface using Fourier transform infrared (FTIR), the X-ray diffraction spectrum (XDS), and the metalloscope. Experimental results show that the outdoor polymeric dielectrics suffer severely and degrade due to acid rain so that their surface electrical properties deteriorate after aging. The erosion, by acid rain, of the energized dielectric materials is larger than that of outdoor materials used for other purposes.

  6. Molecular and microstructural factors affecting mechanical properties of polymeric cover plate materials

    SciTech Connect

    Clark, E.J.

    1985-07-01

    This paper reviews the dependence of mechanical properties of polymers on various microstructural factors. The microstructural and molecular factors considered are: molecular weight, crystallinity, crosslinking, branching, copolymerization, plasticization, orientation, and residual stresses. The types of mechanical properties considered are: direct loading, fatigue, creep, wear and abrasion, and environmental stress cracking. The effects of polymer deformation and fraction at the molecular level are discussed. Cracking, crazing, and shear yielding are described. Polymeric cover plate materials are discussed and their degradation reviewed. Methods to measure microlevel changes in polymers are identified.

  7. Formulation Changes Affect Material Properties and Cell Behavior in HA-Based Hydrogels

    PubMed Central

    Lawyer, Thomas; McIntosh, Kristen; Clavijo, Cristian; Potekhina, Lydia; Mann, Brenda K.

    2012-01-01

    To develop and optimize new scaffold materials for tissue engineering applications, it is important to understand how changes to the scaffold affect the cells that will interact with that scaffold. In this study, we used a hyaluronic acid- (HA-) based hydrogel as a synthetic extracellular matrix, containing modified HA (CMHA-S), modified gelatin (Gtn-S), and a crosslinker (PEGda). By varying the concentrations of these components, we were able to change the gelation time, enzymatic degradation, and compressive modulus of the hydrogel. These changes also affected fibroblast spreading within the hydrogels and differentially affected the proliferation and metabolic activity of fibroblasts and mesenchymal stem cells (MSCs). In particular, PEGda concentration had the greatest influence on gelation time, compressive modulus, and cell spreading. MSCs appeared to require a longer period of adjustment to the new microenvironment of the hydrogels than fibroblasts. Fibroblasts were able to proliferate in all formulations over the course of two weeks, but MSCs did not. Metabolic activity changed for each cell type during the two weeks depending on the formulation. These results highlight the importance of determining the effect of matrix composition changes on a particular cell type of interest in order to optimize the formulation for a given application. PMID:23251160

  8. Material property evaluations of bimetallic welds, stainless steel saw fusion lines, and materials affected by dynamic strain aging

    SciTech Connect

    Rudland, D.; Scott, P.; Marschall, C.; Wilkowski, G.

    1997-04-01

    Pipe fracture analyses can often reasonably predict the behavior of flawed piping. However, there are material applications with uncertainties in fracture behavior. This paper summarizes work on three such cases. First, the fracture behavior of bimetallic welds are discussed. The purpose of the study was to determine if current fracture analyses can predict the response of pipe with flaws in bimetallic welds. The weld joined sections of A516 Grade 70 carbon steel to F316 stainless steel. The crack was along the carbon steel base metal to Inconel 182 weld metal fusion line. Material properties from tensile and C(T) specimens were used to predict large pipe response. The major conclusion from the work is that fracture behavior of the weld could be evaluated with reasonable accuracy using properties of the carbon steel pipe and conventional J-estimation analyses. However, results may not be generally true for all bimetallic welds. Second, the toughness of austenitic steel submerged-arc weld (SAW) fusion lines is discussed. During large-scale pipe tests with flaws in the center of the SAW, the crack tended to grow into the fusion line. The fracture toughness of the base metal, the SAW, and the fusion line were determined and compared. The major conclusion reached is that although the fusion line had a higher initiation toughness than the weld metal, the fusion-line J-R curve reached a steady-state value while the SAW J-R curve increased. Last, carbon steel fracture experiments containing circumferential flaws with periods of unstable crack jumps during steady ductile tearing are discussed. These instabilities are believed to be due to dynamic strain aging (DSA). The paper discusses DSA, a screening criteria developed to predict DSA, and the ability of the current J-based methodologies to assess the effect of these crack instabilities. The effect of loading rate on the strength and toughness of several different carbon steel pipes at LWR temperatures is also discussed.

  9. Properties Affecting the Angle of Repose in a Vertically Vibrated Container of Granular Materials

    NASA Astrophysics Data System (ADS)

    Fox, Odysseus; Quinn, Paul; Tweddle, Thomas

    2014-03-01

    Experiments are conducted using various granular materials subject to a vertical vibration. The angle of repose is studied while varying certain parameters of the system, such as vibration amplitude, vibration frequency, initial height, grain size, container size, and container shape. Empirical relationships are found for the angle of repose as a function of each of these variables. In particular, we compare the results when using a homogeneous material as compared to an inhomogeneous material with varied sizes of particles. We also examine the surface structure and relate it to the propagation of energy through the vibrating system of particles.

  10. Gradient moduli lens models: how material properties and application of forces can affect deformation and distributions of stress

    PubMed Central

    Wang, Kehao; Venetsanos, Demetrios; Wang, Jian; Pierscionek, Barbara K.

    2016-01-01

    The human lens provides one-third of the ocular focussing power and is responsible for altering focus over a range of distances. This ability, termed accommodation, defines the process by which the lens alters shape to increase or decrease ocular refractive power; this is mediated by the ciliary muscle through the zonule. This ability decreases with age such that around the sixth decade of life it is lost rendering the eye unable to focus on near objects. There are two opponent theories that provide an explanation for the mechanism of accommodation; definitive support for either of these requires investigation. This work aims to elucidate how material properties can affect accommodation using Finite Element models based on interferometric measurements of refractive index. Gradients of moduli are created in three models from representative lenses, aged 16, 35 and 48 years. Different forms of zonular attachments are studied to determine which may most closely mimic the physiological form by comparing stress and displacement fields with simulated shape changes to accommodation in living lenses. The results indicate that for models to mimic accommodation in living eyes, the anterior and posterior parts of the zonule need independent force directions. Choice of material properties affects which theory of accommodation is supported. PMID:27507665

  11. Gradient moduli lens models: how material properties and application of forces can affect deformation and distributions of stress.

    PubMed

    Wang, Kehao; Venetsanos, Demetrios; Wang, Jian; Pierscionek, Barbara K

    2016-01-01

    The human lens provides one-third of the ocular focussing power and is responsible for altering focus over a range of distances. This ability, termed accommodation, defines the process by which the lens alters shape to increase or decrease ocular refractive power; this is mediated by the ciliary muscle through the zonule. This ability decreases with age such that around the sixth decade of life it is lost rendering the eye unable to focus on near objects. There are two opponent theories that provide an explanation for the mechanism of accommodation; definitive support for either of these requires investigation. This work aims to elucidate how material properties can affect accommodation using Finite Element models based on interferometric measurements of refractive index. Gradients of moduli are created in three models from representative lenses, aged 16, 35 and 48 years. Different forms of zonular attachments are studied to determine which may most closely mimic the physiological form by comparing stress and displacement fields with simulated shape changes to accommodation in living lenses. The results indicate that for models to mimic accommodation in living eyes, the anterior and posterior parts of the zonule need independent force directions. Choice of material properties affects which theory of accommodation is supported. PMID:27507665

  12. Thickness and material selection of polymeric passive samplers for polycyclic aromatic hydrocarbons in water: Which more strongly affects sampler properties?

    PubMed

    Belles, Angel; Alary, Claire; Mamindy-Pajany, Yannick

    2016-07-01

    Three configurations of single-phase polymer passive samplers made of polyoxymethylene (POM), silicone rubber, and polyethylene (PE) were simultaneously calibrated in laboratory experiments by determining their partitioning coefficients and the POM diffusion coefficients and by validating a kinetic accumulation model. In addition, the performance of each device was evaluated under field conditions. With the support of the developed model, the device properties are discussed with regard to material selection and polymer thickness. The results show that a sampler's properties, such as its concentration-averaging period and ability to sample a large amount of polycyclic aromatic hydrocarbons, are widely affected by material selection. Sampler thickness also allows modulation of the properties of the device but with a much lower magnitude. Selection of the appropriate polymer and/or thickness allows samplers to be adapted either for quick equilibration or for the kinetic accumulation regime and promotes either membrane or water boundary layer control of the kinetic accumulation. In addition, membrane-controlled or equilibrated compounds are quantified with greater accuracy because they are not corrected by the performance reference compounds approach. However, the averaged concentrations cannot be assessed when compounds reach equilibrium in the sampler, whereas membrane-controlled devices remaining in the kinetic accumulation regime provide averaged concentrations without requiring performance reference compound correction; detection limits are then increased because of the higher mass transfer resistance of the membrane. Environ Toxicol Chem 2016;35:1708-1717. © 2015 SETAC. PMID:26647116

  13. How does particle shape affect the near jamming properties of granular materials? Pentagons vs. disks

    NASA Astrophysics Data System (ADS)

    Zhao, Yiqiu; Bares, Jonathan; Behringer, Bob

    Understanding the role of particle shape in system-scale properties is a fundamental challenge in granular physics. We investigated the difference between the response of systems made of pentagons vs. more traditional disks. We performed isotropic compression experiments on 2D photoelastic pentagons and disks near the jamming transition. These experiments show qualitative and quantitative differences in the macroscopic responses of the two systems, such as shifts in the packing fraction at jamming onset and differences in the contact number evolution. Some of these differences are due to a reduction of packing order and the appearance of side-side contacts for the pentatons. We also examined the stress relaxation and dynamical heterogeneity of pentagon particles by performing cyclic compression to allow the system explore phase diagram. We contrast disk and pentagon evolution using four-point-susceptibility and G2 techniques. Work supported by NSF-DMR1206351, DMS1248071, NASA NNX15AD38G, and the W.M. Keck Foundation.

  14. Can you see what you feel? Color and folding properties affect visual-tactile material discrimination of fabrics.

    PubMed

    Xiao, Bei; Bi, Wenyan; Jia, Xiaodan; Wei, Hanhan; Adelson, Edward H

    2016-01-01

    Humans can often estimate tactile properties of objects from vision alone. For example, during online shopping, we can often infer material properties of clothing from images and judge how the material would feel against our skin. What visual information is important for tactile perception? Previous studies in material perception have focused on measuring surface appearance, such as gloss and roughness, and using verbal reports of material attributes and categories. However, in real life, predicting tactile properties of an object might not require accurate verbal descriptions of its surface attributes or categories. In this paper, we use tactile perception as ground truth to measure visual material perception. Using fabrics as our stimuli, we measure how observers match what they see (photographs of fabric samples) with what they feel (physical fabric samples). The data shows that color has a significant main effect in that removing color significantly reduces accuracy, especially when the images contain 3-D folds. We also find that images of draped fabrics, which revealed 3-D shape information, achieved better matching accuracy than images with flattened fabrics. The data shows a strong interaction between color and folding conditions on matching accuracy, suggesting that, in 3-D folding conditions, the visual system takes advantage of chromatic gradients to infer tactile properties but not in flattened conditions. Together, using a visual-tactile matching task, we show that humans use folding and color information in matching the visual and tactile properties of fabrics. PMID:26913626

  15. The physicochemical properties of microwave-assisted encapsulated anthocyanins from Ipomoea batatas as affected by different wall materials

    PubMed Central

    Mohd Nawi, Norazlina; Muhamad, Ida Idayu; Mohd Marsin, Aishah

    2015-01-01

    This study focuses on the impact of different wall materials on the physicochemical properties of microwave-assisted encapsulated anthocyanins from Ipomoea batatas. Using the powder characterization technique, purple sweet potato anthocyanin (PSPAs) powders were analysed for moisture content, water activity, dissolution time, hygroscopicity, color and morphology. PSPAs were produced using different wall materials: maltodextrin (MD), gum arabic (GA) and a combination of gum arabic and maltodextrin (GA + MD) at a 1:1 ratio. Each of the wall materials was homogenized to the core material at a core/wall material ratio of 5 and were microencapsulated by microwave-assisted drying at 1100 W. Results indicated that encapsulated powder with the GA and MD combination presented better quality of powder with the lowest value of moisture content and water activity. With respect to morphology, the microcapsule encapsulated with GA + MD showed several dents in coating surrounding its core material, whereas other encapsulated powders showed small or slight dents entrapped onto the bioactive compound. Colorimetric analysis showed changes in values of L, a*, b*, hue and chroma in the reconstituted powder compared to the initial powder. PMID:25838887

  16. Age Does Not Affect the Material Properties of Expanded Polystyrene Liners in Field-Used Bicycle Helmets.

    PubMed

    Kroeker, Shannon G; Bonin, Stephanie J; DeMarco, Alyssa L; Good, Craig A; Siegmund, Gunter P

    2016-04-01

    Bicycle helmet foam liners absorb energy during impacts. Our goal was to determine if the impact attenuation properties of expanded polystyrene (EPS) foam used in bicycle helmets change with age. Foam cores were extracted from 63 used and unused bicycle helmets from ten different models spanning an age range of 2-20 yrs. All cores were impact tested at a bulk strain rate of 195 s(-1). Six dependent variables were determined from the stress-strain curve derived from each impact (yield strain, yield stress, elastic modulus, plateau slope, energy at 65% compression, and stress at 65% compression), and a general linear model was used to assess the effect of age on each dependent variable with density as a covariate. Age did not affect any of the dependent variables; however, greater foam density, which varied from 58 to 100 kg/m(3), generated significant increases in all of the dependent variables except for yield strain. Higher density foam cores also exhibited lower strains at which densification began to occur, tended to stay within the plateau region of the stress-strain curve, and were not compressed as much compared with the lower density cores. Based on these data, the impact attenuation properties of EPS foam in field-used bicycle helmets do not degrade with the age. PMID:26902784

  17. Ultrasonic material property determinations

    NASA Technical Reports Server (NTRS)

    Serabian, S.

    1986-01-01

    The use and potential offered by ultrasonic velocity and attenuation measurements to determine and/or monitor material properties is explored. The basis for such unique measurements along with examples of materials from a variety of industries are presented.

  18. Building Materials Property Table

    SciTech Connect

    2010-04-16

    This information sheet describes a table of some of the key technical properties of many of the most common building materials taken from ASHRAE Fundamentals - 2001, Moisture Control in Buildings, CMHC, NRC/IRC, IEA Annex 24, and manufacturer data.

  19. Mechanical properties of nanophase materials

    SciTech Connect

    Siegel, R.W.; Fougere, G.E.

    1993-11-01

    It has become possible in recent years to synthesize new materials under controlled conditions with constituent structures on a nanometer size scale (below 100 nm). These novel nanophase materials have grain-size dependent mechanical properties significantly different than those of their coarser-grained counterparts. For example, nanophase metals are much stronger and apparently less ductile than conventional metals, while nanophase ceramics are more ductile and more easily formed than conventional ceramics. The observed mechanical property changes are related to grain size limitations and/or the large percentage of atoms in grain boundary environments; they can also be affected by such features as flaw populations, strains and impurity levels that can result from differing synthesis and processing methods. An overview of what is presently known about the mechanical properties of nanophase materials, including both metals and ceramics, is presented. Some possible atomic mechanisms responsible for the observed behavior in these materials are considered in light of their unique structures.

  20. Rhenium material properties

    NASA Technical Reports Server (NTRS)

    Biaglow, James A.

    1995-01-01

    Tensile data were obtained from four different types of rhenium at ambient and elevated temperatures. The four types of rhenium included chemical vapor deposition (CVD) and three powder metallurgy (PM) types, i.e., rolled sheet and pressed and sintered bars, with and without hot isostatic pressure (HIP) treatment. Results revealed a wide range of values with ultimate strengths at ambient temperatures varying from 663 MPa for CVD rhenium to 943 MPa for rolled sheet. A similar spread was also obtained for material tested at 1088 K and 1644 K. The wide variance observed with the different materials indicated that the rhenium manufacturing process, material composition and prior handling strongly dictated its properties. In addition to tensile properties, CVD, pressed and sintered material and HIP rhenium successfully completed 100 cycles of low cycle fatigue. Creep data were also obtained showing that CVD and pressed and sintered rhenium could sustain five hours of testing under a tension of 27.5 MPa at 1922 K.

  1. Rhenium material properties

    SciTech Connect

    Biaglow, J.A.

    1995-09-01

    Tensile data were obtained from four different types of rhenium at ambient and elevated temperatures. The four types of rhenium included chemical vapor deposition (CVD) and three powder metallurgy (PM) types, i.e., rolled sheet and pressed and sintered bars, with and without hot isostatic pressure (HIP) treatment. Results revealed a wide range of values with ultimate strengths at ambient temperatures varying from 663 MPa for CVD rhenium to 943 MPa for rolled sheet. A similar spread was also obtained for material tested at 1088 K and 1644 K. The wide variance observed with the different materials indicated that the rhenium manufacturing process, material composition and prior handling strongly dictated its properties. In addition to tensile properties, CVD, pressed and sintered material and HIP rhenium successfully completed 100 cycles of low cycle fatigue. Creep data were also obtained showing that CVD and pressed and sintered rhenium could sustain five hours of testing under a tension of 27.5 MPa at 1922 K.

  2. Materials property measurements

    SciTech Connect

    Boyd, D.M.; Green, E.R.; Doctor, S.R.; Good, M.S.

    1990-04-19

    An in-depth review of the measurement techniques that could be used in materials characterization is presented. The measurement techniques to non-destructively determine the in-service or time-related aging of materials considered include ultrasonic velocity and attenuation, eddy current conductivity, neutron scattering and absorption, conventional and tomographic imaging for ultrasonic and radiation imaging, x-ray scattering, thermal impedance, and magnetic hysteresis. The three sections of the report include a review of failure mechanisms in steel and a discussion of nondestructive evaluation techniques and fracture mechanics, a description of a chart on Measurement Techniques versus Material Properties, and recommendations on the techniques and tests to be performed for the experimental investigations and analysis task of the project. 49 refs., 7 figs.

  3. Materials properties data base computerization

    NASA Technical Reports Server (NTRS)

    Baur, R. G.; Donthnier, M. L.; Moran, M. C.; Mortman, I.; Pinter, R. S.

    1984-01-01

    Material property data plays a key role in the design of jet engine components. Consistency, accuracy and efficient use of material property data is of prime importance to the engineering community. The system conception, development, implementation, and future plans for computer software that captures the Material Properties Handbook into a scientific data base are described. The engineering community is given access to raw data and property curves, display of multiple curves for material evaluation and selection, direct access by design analysis computer programs, display of the material specification, and a historical repository for the material evolution. The impact of this activity includes significant productivity gains and cost reductions; all users have access to the same information nd provides consistent, rapid response to the needs of the engineering community. Future plans include incorporating the materials properties data base into a network environment to access information from other data bases and download information to engineering work stations.

  4. Coating agents affected toward magnetite nanoparticles properties

    NASA Astrophysics Data System (ADS)

    Petcharoen, Karat; Sirivat, Anuvat

    2012-02-01

    Magnetite nanoparticles --MNPs-- are innovative materials used in biological and medical applications. They respond to magnetic field through the superparamagnetic behavior at room temperature. In this study, the MNPs were synthesized via the chemical co-precipitation method using various coating agents. Fatty acids, found naturally in the animal fats, can be used as a coating agent. Oleic acid and hexanoic acid were chosen as the surface modification agents to study the improvement in the suspension of MNPs in water and the magnetite properties. Suspension stability, particle size, and electrical conductivity of MNPs are critically affected by the modification process. The well-dispersed MNPs in water can be improved by the surface modification and the oleic acid coated MNPs possess excellent suspension stability over 1 week. The particle size of MNPs increases up to 40 nm using oleic acid coated MNPs. The electrical conductivity of the smallest particle size is 1.3x10-3 S/cm, which is 5 times higher than that of the largest particle, suggesting potential applications as a biomedical material under both of the electrical and magnetic fields.

  5. Tactual perception of liquid material properties.

    PubMed

    Bergmann Tiest, Wouter M

    2015-04-01

    In this paper, studies into the tactual perception of two liquid material properties, viscosity and wetness, are reviewed. These properties are very relevant in the context of interaction with liquids, both real, such as cosmetics or food products, and simulated, as in virtual reality or teleoperation. Both properties have been the subject of psychophysical characterisation in terms of magnitude estimation experiments and discrimination experiments, which are discussed. For viscosity, both oral and manual perception is discussed, as well as the perception of the viscosity of a mechanical system. For wetness, the relevant cues are identified and factors affecting perception are discussed. Finally, some conclusions are drawn pertaining to both properties. PMID:25128819

  6. Psychometric properties of the Affect Phobia Test.

    PubMed

    Frankl, My; Philips, Björn; Berggraf, Lene; Ulvenes, Pål; Johansson, Robert; Wennberg, Peter

    2016-10-01

    The aim of this study was to make the first evaluation of the psychometric properties of the Affect Phobia Test, using the Swedish translation - a test developed to screen the ability to experience, express and regulate emotions. Data was collected from a clinical sample (N = 82) of patients with depression and/or anxiety participating in randomized controlled trial of Internet-based affect-focused treatment, and a university student sample (N = 197). The internal consistency for the total score was satisfactory (Clinical sample α = 0.88/Student sample α = 0.84) as well as for all the affective domains, except Anger/Assertion (α = 0.44/0.36), Sadness/Grief (α = 0.24/0.46) and Attachment/Closeness (α = 0.67/0.69). Test retest reliability was satisfactory (ICC > 0.77) for the total score and for all the affective domains except for Sadness/Grief (ICC = 0.04). The exploratory factor analysis resulted in a six-factor solution and did only moderately match the test's original affective domains. An empirical cut-off between the clinical and the university student sample were calculated and yielded a cut-off of 72 points. As expected, the Affect Phobia test showed negative significant correlations in the clinical group with measures on depression (rxy  = -0.229; p < 0.01) and anxiety (rxy  = -0.315; p < 0.05). The conclusion is that the psychometric properties are satisfactory for the total score of the Affect Phobia Test but not for some of the test's affective domains. Consequently the domains should not be used as subscales. The test can discriminate between individuals who seek help for psychological problems and those who do not. PMID:27461917

  7. Determination of Thermal Properties of Composting Bulking Materials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Thermal properties of compost bulking materials affect temperature and biodegradation during the composting process. Well determined thermal properties of compost feedstocks will therefore contribute to practical thermodynamic approaches. Thermal conductivity, thermal diffusivity, and volumetric hea...

  8. Determination of Thermal Properties of Composting Bulking Materials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Thermal properties of compost bulking materials affect temperature and biodegradation during the composting process. Well-determined thermal properties of compost feedstocks will therefore contribute to practical thermodynamic approaches. Thermal conductivity, thermal diffusivity, and volumetric hea...

  9. Property Status of Lunar Material

    NASA Astrophysics Data System (ADS)

    Pop, V.

    Most of the lunar material in private hands is of meteoric origin, and its property sta- tus does not present many challenges. The intention of Applied Space Resources, Inc, to fly a commercial lunar sample return mission and to subsequently offer lunar ma- terial for sale, raises the issue of the legality of exploitation and private ownership of retrieved lunar material. Lunar samples have been returned in the past by means of the Apollo (US) and Luna (USSR) missions and, while most of the material re- mains government property and is used for scientific means, a small fraction has been transferred abroad and some has entered the private market. Apollo-collected moon- rocks have been offered, symbolically, to heads of States, and some foreign nations have subsequently transferred ownership to private individuals. The same, lunar ma- terial of Soviet provenience has entered the private market, this forming a valuable legal precedent for the lawfulness of sale of lunar material. Recently, plans were made public to award the Apollo astronauts with lunar rocks. While in the US there is a popular misconception that it is illegal to own lunar material, the truth lies elsewhere. As the Apollo samples are the property of the US government and a small fraction was stolen, lost, or misplaced, the US government intends to recover this material, unlawfully owned. In the same time, a significant number of individuals have been prosecuted for offering for sale fake lunar rocks. The present paper will analyse the different categories of lunar material according to its ownership status, and will as- sert that private property of lunar material is lawful, and lunar material that will be returned in the future will be able to enter the market without hindrances.

  10. Properties of aircraft tire materials

    NASA Technical Reports Server (NTRS)

    Dodge, Richard N.; Clark, Samuel K.

    1988-01-01

    A summary is presented of measured elastomeric composite response suitable for linear structural and thermoelastic analysis in aircraft tires. Both real and loss properties are presented for a variety of operating conditions including the effects of temperature and frequency. Suitable micro-mechanics models are used for predictions of these properties for other material combinations and the applicability of laminate theory is discussed relative to measured values.

  11. Functional Properties of Nanostructured Materials

    NASA Astrophysics Data System (ADS)

    Kassing, Rainer; Petkov, Plamen; Kulisch, Wilhelm; Popov, Cyril

    This book, based on the lectures and contributions of the NATO ASI on "Functional Properties of Nanostructured Materials", gives a broad overview on this topic, as it combines basic theoretical articles, papers dealing with experimental techniques, and contributions on advanced and up-to-date applications in fields such as microelectronics, optoelectronics, electrochemistry, sensorics, and biotechnology. In addition, it presents an interdisciplinary approach since the authors came from such different fields as physics, chemistry, engineering, materials science and biology.

  12. Satellite material contaminant optical properties

    NASA Technical Reports Server (NTRS)

    Wood, B. E.; Bertrand, W. T.; Seiber, B. L.; Kiech, E. L.; Falco, P. M.; Holt, J. D.

    1990-01-01

    The Air Force Wright Research and Development Center and the Arnold Engineering Development Center are continuing a program for measuring optical effects of satellite material outgassing products on cryo-optic surfaces. Presented here are infrared (4000 to 700 cm(-1)) transmittance data for contaminant films condensed on a 77 K geranium window. From the transmittance data, the contaminant film refractive and absorptive indices (n, k) were derived using an analytical thin-film interference model with a nonlinear least-squares algorithm. To date 19 materials have been studied with the optical contents determined for 13 of those. The materials include adhesives, paints, composites, films, and lubricants. This program is continuing and properties for other materials will be available in the future.

  13. Dynamic properties of ceramic materials

    SciTech Connect

    Grady, D.E.; Wise, J.L.

    1993-09-01

    Controlled impact methods have been employed to obtain dynamic response properties of armor materials. Experimental data have been obtained for high-strength ceramics. Continued analysis of time-resolved velocity interferometer measurements has produced systematic material-property data for Hugoniot and release response, initial and post-yield strength, pressure-induced phase transformation, and dynamic fracture strength. A new technique has been developed to measure hydrodynamic properties of ceramic through shock-wave experiments on metal-ceramic composites and data obtained for silicon carbide. Additional data on several titanium diboride ceramics and high-quality aluminum oxide ceramic have been acquired, and issues regarding the influence of microstructure on dynamic properties have emerged. Comparison of dynamic (Hugoniot elastic limit) strength and indentation hardness data has been performed and important correlations revealed. Innovative impact experiments on confined and unconfined alumina rods using axial and transverse VISAR diagnostics have been demonstrated which permit acquisition of multiaxial dynamic response data. Dynamic failure properties of a high-density aluminosilicate glass, similar in composition to the intergranular glassy phase of some aluminas, have been investigated with regard to yield, spall, and failure-wave propagation.

  14. Thermal expansion properties of composite materials

    NASA Technical Reports Server (NTRS)

    Johnson, R. R.; Kural, M. H.; Mackey, G. B.

    1981-01-01

    Thermal expansion data for several composite materials, including generic epoxy resins, various graphite, boron, and glass fibers, and unidirectional and woven fabric composites in an epoxy matrix, were compiled. A discussion of the design, material, environmental, and fabrication properties affecting thermal expansion behavior is presented. Test methods and their accuracy are discussed. Analytical approaches to predict laminate coefficients of thermal expansion (CTE) based on lamination theory and micromechanics are also included. A discussion is included of methods of tuning a laminate to obtain a near-zero CTE for space applications.

  15. Material properties of oxide superconductors

    SciTech Connect

    Phillips, J.C.

    1996-12-31

    The differences between the old (inter-) metallic superconductors and the new oxide superconductors are not limited to the much higher values of {Tc} attainable in the latter. There are many pervasive differences caused directly by oxide chemistry, quasi-perovskite local coordination configurations, and layered metal-semiconductor-metal{prime}-semiconductor-structures. When these differences are ignored, for instance in theoretical models which make effective medium approximations, many experiments appear to present anomalous results. These anomalies largely disappear when account is taken of the real materials properties of the cuprates and other new oxide superconductors, for instance in theoretical models which treat transport as a partially percolative process. This percolative process directly reflects the fact that the highest values of {Tc}, as well as the most anomalous normal-state transport properties, occur in materials vicinal to a metal-insulator transition. As the metallic and insulating regions alternate even in single-crystal samples, effective medium models, and most effective-medium parameters, lose their significance. Examples of attempts to measure microscopic properties illustrate the importance of filamentary effects on both normal-state and superconductive properties.

  16. Mechanical processess affecting differentiation of protolunar material

    NASA Technical Reports Server (NTRS)

    Kaula, W. M.

    1977-01-01

    Mechanisms prior to lunar formation are sought to account for the loss of volatiles, the depletion of iron, and the enrichment of plagioclase. Some of the same mechanisms are necessary to account for achondritic, stony-iron, and iron meteorites. Collisions seem marginally capable of providing the heat to accomplish the differentiation into iron, magnesian silicates, and plagioclase. Once this differentiation is accomplished, the subsequent mechanical history should have been sufficient to sort material according to composition in the protolunar circumterrestrial cloud. Effects operating include the correlation of body size with mechanical strength; the lesser ability of the cloud to trap the larger, denser infalling bodies; the more rapid drawing into the Earth of the larger moonlets; and the higher energy orbits for dominantly plagioclase smaller pieces broken off by collision.

  17. Mechanical Properties of Heat Affected Zone of High Strength Steels

    NASA Astrophysics Data System (ADS)

    Sefcikova, K.; Brtnik, T.; Dolejs, J.; Keltamaki, K.; Topilla, R.

    2015-11-01

    High Strength Steels became more popular as a construction material during last decade because of their increased availability and affordability. On the other hand, even though general use of Advanced High Strength Steels (AHSS) is expanding, the wide utilization is limited because of insufficient information about their behaviour in structures. The most widely used technique for joining steels is fusion welding. The welding process has an influence not only on the welded connection but on the area near this connection, the so-called heat affected zone, as well. For that reason it is very important to be able to determine the properties in the heat affected zone (HAZ). This area of investigation is being continuously developed in dependence on significant progress in material production, especially regarding new types of steels available. There are currently several types of AHSS on the world market. Two most widely used processes for AHSS production are Thermo-Mechanically Controlled Processing (TMCP) and Quenching in connection with Tempering. In the presented study, TMCP and QC steels grade S960 were investigated. The study is focused on the changes of strength, ductility, hardness and impact strength in heat affected zone based on the used amount of heat input.

  18. Tillage system affects microbiological properties of soil

    NASA Astrophysics Data System (ADS)

    Delgado, A.; de Santiago, A.; Avilés, M.; Perea, F.

    2012-04-01

    Soil tillage significantly affects organic carbon accumulation, microbial biomass, and subsequently enzymatic activity in surface soil. Microbial activity in soil is a crucial parameter contributing to soil functioning, and thus a basic quality factor for soil. Since enzymes remain soil after excretion by living or disintegrating cells, shifts in their activities reflect long-term fluctuations in microbial biomass. In order to study the effects of no-till on biochemical and microbiological properties in comparison to conventional tillage in a representative soil from South Spain, an experiment was conducted since 1982 on the experimental farm of the Institute of Agriculture and Fisheries Research of Andalusia (IFAPA) in Carmona, SW Spain (37o24'07''N, 5o35'10''W). The soil at the experimental site was a very fine, montomorillonitic, thermic Chromic Haploxerert (Soil Survey Staff, 2010). A randomized complete block design involving three replications and the following two tillage treatments was performed: (i) Conventional tillage, which involved mouldboard plowing to a depth of 50 cm in the summer (once every three years), followed by field cultivation to a depth of 15 cm before sowing; crop residues being burnt, (ii) No tillage, which involved controlling weeds before sowing by spraying glyphosate and sowing directly into the crop residue from the previous year by using a planter with double-disk openers. For all tillage treatments, the crop rotation (annual crops) consisted of winter wheat, sunflower, and legumes (pea, chickpea, or faba bean, depending on the year), which were grown under rainfed conditions. Enzymatic activities (ß-glucosidase, dehydrogenase, aryl-sulphatase, acid phosphatase, and urease), soil microbial biomass by total viable cells number by acridine orange direct count, the density of cultivable groups of bacteria and fungi by dilution plating on semi-selective media, the physiological profiles of the microbial communities by BiologR, and the

  19. Do cluster properties affect the quenching rate?

    NASA Astrophysics Data System (ADS)

    Raichoor, A.; Andreon, S.

    2014-10-01

    The quenching rate is known to depend on galaxy stellar mass and environment, however, possible dependences on the hosting halo properties, such as mass, richness, and dynamical status, are still debated. The determination of these dependences is hampered by systematics, induced by noisy estimates of cluster mass or by the lack of control on galaxy stellar mass, which may mask existing trends or introduce fake trends. We studied a sample of local clusters (20 with 0.02 < z < 0.1 and log (M200/M⊙) ≳ 14), selected independent of the galaxy properties under study, having homogeneous optical photometry and X-ray estimated properties. Using those top quality measurements of cluster mass, hence of cluster scale, richness, iron abundance, and cooling time/presence of a cool-core, we study the simultaneous dependence of quenching on these cluster properties on galaxy stellar mass M and normalised cluster-centric distance r/r200. We found that the quenching rate can be completely described by two variables only, galaxy stellar mass and normalised cluster-centric distance, and is independent of halo properties (mass, richness, iron abundance, and central cooling time/presence of a cool-core). These halo properties change, in most cases, by less than 3% the probability that a galaxy is quenched, once the mass-size (M200 - r200) scaling relation is accounted for through cluster-centric distance normalisation. Appendix A is available in electronic form at http://www.aanda.org

  20. Factors affecting mechanical properties of biomass pellet from compost.

    PubMed

    Zafari, A; Kianmehr, M H

    2014-01-01

    Effectiveness of a densification process to create strong and durable bonding in pellets can be determined by testing the mechanical properties such as compressive strength (CS) and durability. Mechanical properties of pellet from composted municipal solid waste were determined at different raw material and densification conditions. Ground compost samples were compressed with three levels of moisture content (35%, 40% and 45% (wb)), piston compaction speed (2, 6 and 10 mm/s), die length (8, 10 and 12mm) and raw material particle size (0.3, 0.9 and 1.5mm) into cylindrical pellets utilizing opened-end dies under axial stress from a vertical piston applied by a hydraulic press. The effects of independent variables on mechanical properties were determined using response surface methodology based on Box-Behnken design (BBD). All independent variables affected the durability significantly. However, different piston speed and die length not produce any significant difference on CS of pellets. Also in this research the electron photography method was used to identify the binding mechanism of compost particles. PMID:24600888

  1. Factors affecting the dielectric properties of agricultural and food products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dielectric properties of materials are defined, and the major factors that influence these properties of agricultural and food materials, namely, frequency of the applied radio-frequency and microwave electric fields, water content, temperature, and density of the materials are discussed on the bas...

  2. Factors Affecting the Textural Properties of Pork

    ERIC Educational Resources Information Center

    Holmer, Sean Frederick

    2009-01-01

    Research concerning rate and extent of tenderization has focused on beef or lamb. However, it is critical to understand these processes in pork, especially as retailers move towards minimally processed or non-enhanced product. The objectives of this experiment were to evaluate the textural properties of pork (firmness and tenderness) by examining…

  3. Property Data Summaries for Advanced Materials

    National Institute of Standards and Technology Data Gateway

    SRD 150 NIST Property Data Summaries for Advanced Materials (Web, free access)   Property Data Summaries are topical collections of property values derived from surveys of published data. Thermal, mechanical, structural, and chemical properties are included in the collections.

  4. NIST Materials Properties Databases for Advanced Ceramics

    PubMed Central

    Munro, R. G.

    2001-01-01

    The NIST Ceramics Division maintains two databases on the physical, mechanical, thermal, and other properties of high temperature superconductors and structural ceramics. Crystallographic data are featured prominently among the physical property data and serve several important functions in the classification and evaluation of the property values. The scope of materials, properties, and data evaluation protocols are discussed for the two databases.

  5. A Bibliography of Affective Materials for the Adolescent Years.

    ERIC Educational Resources Information Center

    Bolen, Jackie

    The annotated bibliography lists approximately 146 instructional materials and books useful to teachers who deal with normal and abnormal adolescent affective behavior in junior and senior high schools. An explanation sheet gives instructions for correlating publisher with a specific material, and for finding items according to topic categories. A…

  6. City snow's physicochemical property affects snow disposal

    NASA Astrophysics Data System (ADS)

    Dovbysh, V. O.; Sharukha, A. V.; Evtin, P. V.; Vershinina, S. V.

    2015-10-01

    At the present day the industrial cities run into severe problem: fallen snow in a city it's a concentrator of pollutants and their quantity is constantly increasing by technology development. Pollution of snow increases because of emission of gases to the atmosphere by cars and factories. Large accumulation of polluted snow engenders many vexed ecological problems. That's why we need a new, non-polluting, scientifically based method of snow disposal. This paper investigates polluted snow's physicochemical property effects on snow melting. A distinctive feature of the ion accelerators with self-magnetically insulated diode is that there.

  7. Materialism, affective states, and life satisfaction: case of Croatia.

    PubMed

    Lipovčan, Ljiljana Kaliterna; Prizmić-Larsen, Zvjezdana; Brkljačić, Tihana

    2015-01-01

    In recent years, a number of studies have used Material Values Scale (MVS) to assess beliefs about importance to own material things. The aims of this study were to validate the MVS scale and to explore the relationships between materialistic values and well-being of Croatian citizens. The study was carried out on a representative sample of N = 1129 Croatian citizens. We used the short 9-item version of the MVS, life satisfaction rating, ratings of two positive (Positive affect) and four negative emotions (Negative affect) over the past month, and demographic variables (age, gender, income). The original dimensionality of the MVS was not confirmed; confirmatory factor analyses yielded two instead of three factors, Happiness and Centrality/Success. When controlled for income, gender and age, the Happiness dimension predicted Life satisfaction and both Positive and Negative affect, indicating that people who believed that the material goods in ones life leads to happiness reported to have lower life satisfaction, lower level of positive affect and higher level of negative affect over the past month. The Centrality/Success dimension was positively related to Positive affect, indicating that the belief that possessions play a central role in enjoyment leads to more frequent experiences of happiness and satisfaction over the past month. PMID:26587367

  8. Acoustical properties of double porosity granular materials.

    PubMed

    Venegas, Rodolfo; Umnova, Olga

    2011-11-01

    Granular materials have been conventionally used for acoustic treatment due to their sound absorptive and sound insulating properties. An emerging field is the study of the acoustical properties of multiscale porous materials. An example of these is a granular material in which the particles are porous. In this paper, analytical and hybrid analytical-numerical models describing the acoustical properties of these materials are introduced. Image processing techniques have been employed to estimate characteristic dimensions of the materials. The model predictions are compared with measurements on expanded perlite and activated carbon showing satisfactory agreement. It is concluded that a double porosity granular material exhibits greater low-frequency sound absorption at reduced weight compared to a solid-grain granular material with similar mesoscopic characteristics. PMID:22087905

  9. Synthesis and properties of nanophase materials

    SciTech Connect

    Siegel, R.W.

    1993-03-01

    Nanophase materials, with their grain sizes or phase dimensions in the nanometer size regime, are now being produced by a wide variety of synthesis and processing methods. The interest in these new ultrafine-grained materials results primarily from the special nature of their various physical, chemical, and mechanical properties and the possibilities to control these properties during the synthesis and subsequent processing procedures. Since it is now becoming increasingly apparent that their properties can be engineered effectively during synthesis and processing, and that they can also be produced in quantity, nanophase materials should have considerable potential for technological development in a variety of applications. Some of the recent research on nanophase materials related to their synthesis and properties is briefly reviewed and the future potential of these new materials is considered.

  10. Dynamic properties of ceramic materials

    SciTech Connect

    Grady, D.E.

    1995-02-01

    The present study offers new data and analysis on the transient shock strength and equation-of-state properties of ceramics. Various dynamic data on nine high strength ceramics are provided with wave profile measurements, through velocity interferometry techniques, the principal observable. Compressive failure in the shock wave front, with emphasis on brittle versus ductile mechanisms of deformation, is examined in some detail. Extensive spall strength data are provided and related to the theoretical spall strength, and to energy-based theories of the spall process. Failure waves, as a mechanism of deformation in the transient shock process, are examined. Strength and equation-of-state analysis of shock data on silicon carbide, boron carbide, tungsten carbide, silicon dioxide and aluminum nitride is presented with particular emphasis on phase transition properties for the latter two. Wave profile measurements on selected ceramics are investigated for evidence of rate sensitive elastic precursor decay in the shock front failure process.

  11. Design of materials with prescribed nonlinear properties

    NASA Astrophysics Data System (ADS)

    Wang, F.; Sigmund, O.; Jensen, J. S.

    2014-09-01

    We systematically design materials using topology optimization to achieve prescribed nonlinear properties under finite deformation. Instead of a formal homogenization procedure, a numerical experiment is proposed to evaluate the material performance in longitudinal and transverse tensile tests under finite deformation, i.e. stress-strain relations and Poissons ratio. By minimizing errors between actual and prescribed properties, materials are tailored to achieve the target. Both two dimensional (2D) truss-based and continuum materials are designed with various prescribed nonlinear properties. The numerical examples illustrate optimized materials with rubber-like behavior and also optimized materials with extreme strain-independent Poissons ratio for axial strain intervals of εi∈[0.00, 0.30].

  12. Learning targeted materials properties from data

    NASA Astrophysics Data System (ADS)

    Lookman, Turab; Balachandran, Prasanna V.; Dezhen, Xue; Theiler, James; Hogden, John

    We compare several strategies using a data set of 223 M2AX family of compounds for which the elastic properties [bulk (B), shear (G), and Young's (E) modulus] have been computed using density functional theory. The strategy is decomposed into two steps: a regressor is trained to predict elastic properties in terms of elementary orbital radii of the individual components of the materials; and a selector uses these predictions to choose the next material to investigate. The ultimate goal is to obtain a material with desired elastic properties. We examine how the choice of data set size, regressor and selector impact the results.

  13. Switchgrass affects on soil property changes in the Great Plains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The capacity of perennial grasses to affect change in soil properties is well documented but soil property information on switchgrass (Panicum virgatum L.) managed for bioenergy is limited. Potential improvements in near-surface soil function are important should switchgrass be included as a perenn...

  14. Synthesis, properties, and applications of nanophase materials

    SciTech Connect

    Siegel, R.W. |

    1995-04-01

    Work on the synthesis, properties, and applications of nanophase materials has developed rapidly during the past decade. A wide variety of methods now exist for their production, including several plasma-based processes. The possibilities for engineering new materials with unique or improved properties for a number of applications is now evident from the extant research results. A brief review is presented here along with some examples of useful application areas and some thoughts for the future of this field.

  15. Materials Properties Research at MSFC

    NASA Technical Reports Server (NTRS)

    Presson, Joan B.; Burdine, Robert (Technical Monitor)

    2002-01-01

    MSFC is currently planning, organizing and directing test coupon fabrication and subsequent CTE testing for two mirror materials of specific interest to the AMSD and NGST programs, Beryllium 0-30H (Be 0-30H) and Ultra Low Expansion glass (ULE). The ULE test coupons are being fabricated at MSFC from AMSD core residuals provided by Kodak, The Be 0-30H test coupons are being fabricated at Brush Wellman using residuals from the SBMD. Both sets of test coupons will be sent to a test vendor selected through the NASA competitive proposal process with the test results being provided by written report to MSFC by the end of the fiscal year. The test results will become model input data for the AMSD analysts, both MSFC and contractor, providing an enhancement to the historical CTE data currently available.

  16. Spacecraft Charging Sensitivity to Material Properties

    NASA Technical Reports Server (NTRS)

    Minow, Joseph I.; Edwards, David L.

    2015-01-01

    Evaluating spacecraft charging behavior of a vehicle in the space environment requires knowledge of the material properties relevant to the charging process. Implementing surface and internal charging models requires a user to specify a number of material electrical properties including electrical resistivity parameters (dark and radiation induced), dielectric constant, secondary electron yields, photoemission yields, and breakdown strength in order to correctly evaluate the electric discharge threat posed by the increasing electric fields generated by the accumulating charge density. In addition, bulk material mass density and/or chemical composition must be known in order to analyze radiation shielding properties when evaluating internal charging. We will first describe the physics of spacecraft charging and show how uncertainties in material properties propagate through spacecraft charging algorithms to impact the results obtained from charging models. We then provide examples using spacecraft charging codes to demonstrate their sensitivity to material properties. The goal of this presentation is to emphasize the importance in having good information on relevant material properties in order to best characterize on orbit charging threats.

  17. Nonlinear optical properties of composite materials

    NASA Technical Reports Server (NTRS)

    Haus, Joseph W.; Inguva, Ramarao

    1991-01-01

    The optical properties of a new class of composite nonlinear materials composed of coated grains, such as cadmium sulfide with a silver coating, are examined. These materials exhibit intrinsic optical bistability and resonantly enhanced conjugate reflectivity. The threshold for intrinsic optical bistability is low enough for practical applications in optical communications and optical computing. Some problems associated with the fabrication of these materials are addressed. Based on preliminary results, switching times are expected to be in the subpicosecond range.

  18. Repair material properties for effective structural application

    SciTech Connect

    Mangat, P.S.; Limbachiya, M.C.

    1997-04-01

    Strength and engineering properties of three generic repair materials which are likely to influence long-term performance of repaired concrete structures were studied. Measured properties include strength, stiffness, shrinkage and creep deformations, together with the complete compressive stress-strain characteristics including post-cracking behavior. The repair materials considered in this investigation are commercially available and widely used. These included a high performance non-shrinkable concrete, a mineral based cementitious material with no additives or coarse aggregate size particles, and a cementitious mortar containing styrene acrylic copolymer with fiber additives. Performance comparisons are also made between these materials and plain concrete mixes of similar strength and stiffness, suitable for repair applications. The results show that shrinkage of the repair materials was significantly greater than the shrinkage of normal concrete. Moreover, the shrinkage of those modified with a polymer admixture was found to be very sensitive to the relative humidity of the exposure compared to normal concrete. The post-peak strain capacity of the material modified with a polymer admixture was markedly improved leading to a more pronounced falling branch of stress-strain curve. The ultimate stress level (at a maximum load) of specially formulated repair materials varies significantly, the lowest ultimate stress being recorded for the porous mineral-based material. The inclusion of aggregates improves the mechanical properties and dimensional stability of repair materials.

  19. Material properties of novel polymeric films

    NASA Astrophysics Data System (ADS)

    Kim, Gene

    This dissertation will study the material properties of two types of novel polymer films (polyelectrolyte multilayer films and photolithographic polymer films). The formation of polylelectrolyte multilayer films onto functionalized aluminum oxide surfaces and functionalized poly(ethylene terephthaltate) (PET) were studied. Functionalization of the aluminum oxide surfaces was achieved via silane coupling. Functionalization of PET surfaces was achieved via hydrolysis and amidation. Surface characterization techniques such as X-ray photoelectron spectroscopy (XPS) and dynamic contact angle measurements were used to monitor the polyelectrolyte multilayer formation. Mechanical properties of the aluminum oxide supported polyelectrolyte multilayer films were tested using a simplified peel test. XPS was used to analyze the surfaces before and after peel. Single lap shear joint specimens were constructed to test the adhesive shear strength of the PET-supported polyelectrolyte multilayer film samples with the aid of a cyanoacrylate adhesive. The adhesive shear strength and its relation with the type of functionalization, number of polyelectrolyte layers, and the effect of polyelectrolyte conformation using added salt were explored. Also, characterization on the single lap joints after adhesive failure was carried out to determine the locus of failure within the multilayers by using XPS and SEM. Two types of photolithographic polymers were formulated and tested. These two polymers (photocrosslinkable polyacrylate (PUA), and a photocrosslinkable polyimide (HRP)) were used to investigate factors that would affect the structural integrity of these particular polymers under environmental variables such as processing (time, UV cure, pressure, and temperature) and ink exposure. Thermomechanical characterization was carried out to see the behavior of these two polymers under these environmental variables. Microscopic techniques were employed to study the morphological behavior of

  20. From Microstructures to Predict Properties of Materials

    NASA Astrophysics Data System (ADS)

    Wang, Ke-Gang

    2010-03-01

    Understanding the precise and fundamental manner in which materials structures (nanostructures or microstructures) and their evolution influences properties and service lifetimes of advanced materials profoundly impacts material design and today materials design plays an increasingly important rôle in many engineering applications. Linking structures to properties and predicting properties of materials is fundamental step for materials design. First, a framework of applications of multiscale modeling to property prediction of advanced materials will be briefly presented. As an example, a methodology will be shown to link micro-scale to the continuum scale, integrating microstructure modeling with the large Thermo-Calc^ database. This paradigm was successfully applied to the case of Fe-12Ni-6Mn maraging steel. Next, methodology for integrating first-principle calculation into simulations of microstructure evolution will be reviewed. Our methods are sufficiently reliable to permit control and fabrication of quantum-dots structures, nanocrystals, and particle-reinforced nanocomposites, as well as assist in the predictive behavior of macro-scale colloids, aerosols, and other soft matter systems.

  1. Factors affecting coercivity in rare-earth based advanced permanent magnet materials

    SciTech Connect

    Lewis, L.H.; Sellers, C.H.; Panchanathan, V.

    1997-02-01

    The relationships that link microstructural properties of advanced permanent magnet materials with magnetic properties such as the coercivity are often difficult to quantify, especially in materials with nano-scale structures. Recent work on RE{sub 2}Fe{sub 14}B-based powders fabricated with rapid-solidification techniques such as inert gas atomization (IGA) and melt-spinning provide insight into the nanostructural features which affect the acquisition and stability of coercivity. In all cases the coercivity is found to be a function of both the scale of the constituent microstructure and of the presence and distribution of minor phases.

  2. Thermal protection materials: Thermophysical property data

    NASA Technical Reports Server (NTRS)

    Williams, S. D.; Curry, Donald M.

    1992-01-01

    This publication presents a thermophysical property survey on materials that could potentially be used for future spacecraft thermal protection systems (TPS). This includes data that was reported in the 1960's as well as more current information reported through the 1980's. An attempt was made to cite the manufacturers as well as the data source in the bibliography. This volume represents an attempt to provide in a single source a complete set of thermophysical data on a large variety of materials used in spacecraft TPS analysis. The property data is divided into two categories: ablative and reusable. The ablative materials have been compiled into twelve categories that are descriptive of the material composition. An attempt was made to define the Arrhenius equation for each material although this data may not be available for some materials. In a similar manner, char data may not be available for some of the ablative materials. The reusable materials have been divided into three basic categories: thermal protection materials (such as insulators), adhesives, and structural materials.

  3. Understanding and Tailoring the Mechanical Properties of LIGA Fabricated Materials

    SciTech Connect

    Buchheit, T.E.; Christenson, T.R.; Lavan, D.A.; Schmale, D.T.

    1999-01-25

    LIGA fabricated materials and components exhibit several processing issues affecting their metallurgical and mechanical properties, potentially limiting their usefulness for MEMS applications. For example, LIGA processing by metal electrodeposition is very sensitive to deposition conditions which causes significant processing lot variations of mechanical and metallurgical properties. Furthermore, the process produces a material with a highly textured lenticular rnicrostructural morphology suggesting an anisotropic material response. Understanding and controlling out-of-plane anisotropy is desirable for LIGA components designed for out-of-plane flexures. Previous work by the current authors focused on results from a miniature servo-hydraulic mechanical test frame constructed for characterizing LIGA materials. Those results demonstrated microstructural and mechanical properties dependencies with plating bath current density in LIGA fabricated nickel (LIGA Ni). This presentation builds on that work and fosters a methodology for controlling the properties of LIGA fabricated materials through processing. New results include measurement of mechanical properties of LIGA fabricated copper (LIGA Cu), out-of-plane and localized mechanical property measurements using compression testing and nanoindentation of LIGA Ni and LIGA Cu.

  4. How Molecular Structure Affects Mechanical Properties of an Advanced Polymer

    NASA Technical Reports Server (NTRS)

    Nicholson, Lee M.; Whitley, Karen S.; Gates, Thomas S.; Hinkley, Jeffrey A.

    2000-01-01

    density was performed over a range of temperatures below the glass transition temperature. The physical characterization, elastic properties and notched tensile strength all as a function of molecular weight and test temperature were determined. For the uncrosslinked SI material, it was shown that notched tensile strength is a strong function of both temperature and molecular weight, whereas stiffness is only a strong function of temperature. For the crosslinked PETI-SI material, it was shown that the effect of crosslinking significantly enhances the mechanical performance of the low molecular weight material; comparable to that exhibited by the high molecular weight material.

  5. High Strength Stainless Steel Properties that Affect Resistance Welding

    SciTech Connect

    Kanne, W.R.

    2001-08-01

    This report discusses results of a study on selected high strength stainless steel alloy properties that affect resistance welding. The austenitic alloys A-286, JBK-75 (Modified A-286), 21-6-9, 22-13-5, 316 and 304L were investigated and compared. The former two are age hardenable, and the latter four obtain their strength through work hardening. Properties investigated include corrosion and its relationship to chemical cleaning, the effects of heat treatment on strength and surface condition, and the effect of mechanical properties on strength and weldability.

  6. ESTEC wiring test programme materials related properties

    NASA Technical Reports Server (NTRS)

    Judd, M. D.

    1994-01-01

    Electrical wires are considered as EEE parts and are covered within the ESA SCC specification series (ESA SCC 3901/XXX). This specification defines the principal properties of the wires including insulation/lay-up and electrical properties. Some additional space related materials requirements are also included, requirements such as outgassing and silver plating thickness. If a project has additional materials requirements over and above those covered by the relevant SCC specification, then additional testing is required. This is especially true for crewed spacecraft. The following topics are discussed in this context: additional requirements for manned spacecraft; flammability; arc tracking; thermal decomposition; microbial surface growth; and ageing.

  7. Upgrades to the TPSX Material Properties Database

    NASA Technical Reports Server (NTRS)

    Squire, T. H.; Milos, F. S.; Partridge, Harry (Technical Monitor)

    2001-01-01

    The TPSX Material Properties Database is a web-based tool that serves as a database for properties of advanced thermal protection materials. TPSX provides an easy user interface for retrieving material property information in a variety of forms, both graphical and text. The primary purpose and advantage of TPSX is to maintain a high quality source of often used thermal protection material properties in a convenient, easily accessible form, for distribution to government and aerospace industry communities. Last year a major upgrade to the TPSX web site was completed. This year, through the efforts of researchers at several NASA centers, the Office of the Chief Engineer awarded funds to update and expand the databases in TPSX. The FY01 effort focuses on updating correcting the Ames and Johnson thermal protection materials databases. In this session we will summarize the improvements made to the web site last year, report on the status of the on-going database updates, describe the planned upgrades for FY02 and FY03, and provide a demonstration of TPSX.

  8. 7 CFR 1955.105 - Real property affected (CONACT).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 14 2011-01-01 2011-01-01 false Real property affected (CONACT). 1955.105 Section 1955.105 Agriculture Regulations of the Department of Agriculture (Continued) RURAL HOUSING SERVICE, RURAL BUSINESS-COOPERATIVE SERVICE, RURAL UTILITIES SERVICE, AND FARM SERVICE AGENCY, DEPARTMENT OF AGRICULTURE (CONTINUED) PROGRAM REGULATIONS...

  9. 7 CFR 1955.105 - Real property affected (CONACT).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 14 2010-01-01 2009-01-01 true Real property affected (CONACT). 1955.105 Section 1955.105 Agriculture Regulations of the Department of Agriculture (Continued) RURAL HOUSING SERVICE, RURAL BUSINESS-COOPERATIVE SERVICE, RURAL UTILITIES SERVICE, AND FARM SERVICE AGENCY, DEPARTMENT OF AGRICULTURE (CONTINUED) PROGRAM REGULATIONS...

  10. Spectral reflectance properties of carbon-bearing materials

    NASA Astrophysics Data System (ADS)

    Cloutis, E. A.; Gaffey, M. J.; Moslow, T. F.

    1994-02-01

    The 0.3-2.6 micrometers spectral reflectance properties of carbon polymorphs (graphite, carbon black, diamond), carbides (silicon carbide, cementite), and macromolecular organic-bearing materials (coal, coal tar extract, oil sand, oil shale) are found to vary from sample to sample and among groups. The carbon polymorphs are readily distinguishable on the basis of their visible-near infrared spectral slopes and shapes. The spectra of macromolecular organic-bearing materials show increases in reflectance toward longer wavelengths, exceeding the reflectance rise of more carbon-rich materials. Reflectance spectra of carbonaceous materials are affected by the crystal structure, composition, and degree of order/disorder of the samples. The characteristic spectral properties can potentially be exploited to identify individual carbonaceous grains in meteorites (as separates or in situ) or to conduct remote sensing geothermometry and identification of carbonaceous phases on asteroids.

  11. Spectral reflectance properties of carbon-bearing materials

    NASA Technical Reports Server (NTRS)

    Cloutis, Edward A.; Gaffey, Michael J.; Moslow, Thomas F.

    1994-01-01

    The 0.3-2.6 micrometers spectral reflectance properties of carbon polymorphs (graphite, carbon black, diamond), carbides (silicon carbide, cementite), and macromolecular organic-bearing materials (coal, coal tar extract, oil sand, oil shale) are found to vary from sample to sample and among groups. The carbon polymorphs are readily distinguishable on the basis of their visible-near infrared spectral slopes and shapes. The spectra of macromolecular organic-bearing materials show increases in reflectance toward longer wavelengths, exceeding the reflectance rise of more carbon-rich materials. Reflectance spectra of carbonaceous materials are affected by the crystal structure, composition, and degree of order/disorder of the samples. The characteristic spectral properties can potentially be exploited to identify individual carbonaceous grains in meteorites (as separates or in situ) or to conduct remote sensing geothermometry and identification of carbonaceous phases on asteroids.

  12. Properties of Extruded PS-212 Type Self-Lubricating Materials

    NASA Technical Reports Server (NTRS)

    Waters, W. J.; Sliney, H. E.; Soltis, R. F.

    1993-01-01

    Research has been underway at the NASA Lewis Research Center since the 1960's to develop high temperature, self-lubricating materials. The bulk of the research has been done in-house by a team of researchers from the Materials Division. A series of self-lubricating solid material systems has been developed over the years. One of the most promising is the composite material system referred to as PS-212 or PM-212. This material is a powder metallurgy product composed of metal bonded chromium carbide and two solid lubricating materials known to be self-lubricating over a wide temperature range. NASA feels this material has a wide potential in industrial applications. Simplified processing of this material would enhance its commercial potential. Processing changes have the potential to reduce processing costs, but tribological and physical properties must not be adversely affected. Extrusion processing has been employed in this investigation as a consolidation process for PM-212/PS-212. It has been successful in that high density bars of EX-212 (extruded PM-212) can readily be fabricated. Friction and strength data indicate these properties have been maintained or improved over the P.M. version. A range of extrusion temperatures have been investigated and tensile, friction, wear, and microstructural data have been obtained. Results indicate extrusion temperatures are not critical from a densification standpoint, but other properties are temperature dependent.

  13. Mechanisms affecting kinetic energies of laser-ablated materials

    SciTech Connect

    Chen, K.R. |; Leboeuf, J.N.; Wood, R.F.; Geohegan, D.B.; Donato, J.M.; Liu, C.L.; Puretzky, A.A.

    1995-12-31

    Laser materials processing techniques are expected to have a dramatic impact on materials science and engineering in the near future and beyond. One of the main laser materials processing techniques is Pulsed Laser Deposition (PLD) for thin film growth. While experimentalists search for optimal approaches for thin film growth with pulsed laser deposition (PLD), a systematic effort in theory and modeling of various processes during PLD is needed. The quality of film deposited depends critically on the range and profile of the kinetic energy and density of the ablated plume. While it is to the advantage of pulsed laser deposition to have high kinetic energy, plumes that are too energetic causes film damage. A dynamic source effect was found to accelerate the plume expansion velocity much higher than that from a conventional free expansion model. A self-similar theory and a hydrodynamic model are developed to study this effect, which may help to explain experimentally observed high front expansion velocity. Background gas can also affect the kinetic energies. High background gas may cause the ablated materials to go backward. Experimentally observed plume splitting is also discussed.

  14. Type of Speech Material Affects Acceptable Noise Level Test Outcome.

    PubMed

    Koch, Xaver; Dingemanse, Gertjan; Goedegebure, André; Janse, Esther

    2016-01-01

    The acceptable noise level (ANL) test, in which individuals indicate what level of noise they are willing to put up with while following speech, has been used to guide hearing aid fitting decisions and has been found to relate to prospective hearing aid use. Unlike objective measures of speech perception ability, ANL outcome is not related to individual hearing loss or age, but rather reflects an individual's inherent acceptance of competing noise while listening to speech. As such, the measure may predict aspects of hearing aid success. Crucially, however, recent studies have questioned its repeatability (test-retest reliability). The first question for this study was whether the inconsistent results regarding the repeatability of the ANL test may be due to differences in speech material types used in previous studies. Second, it is unclear whether meaningfulness and semantic coherence of the speech modify ANL outcome. To investigate these questions, we compared ANLs obtained with three types of materials: the International Speech Test Signal (ISTS), which is non-meaningful and semantically non-coherent by definition, passages consisting of concatenated meaningful standard audiology sentences, and longer fragments taken from conversational speech. We included conversational speech as this type of speech material is most representative of everyday listening. Additionally, we investigated whether ANL outcomes, obtained with these three different speech materials, were associated with self-reported limitations due to hearing problems and listening effort in everyday life, as assessed by a questionnaire. ANL data were collected for 57 relatively good-hearing adult participants with an age range representative for hearing aid users. Results showed that meaningfulness, but not semantic coherence of the speech material affected ANL. Less noise was accepted for the non-meaningful ISTS signal than for the meaningful speech materials. ANL repeatability was comparable across

  15. Type of Speech Material Affects Acceptable Noise Level Test Outcome

    PubMed Central

    Koch, Xaver; Dingemanse, Gertjan; Goedegebure, André; Janse, Esther

    2016-01-01

    The acceptable noise level (ANL) test, in which individuals indicate what level of noise they are willing to put up with while following speech, has been used to guide hearing aid fitting decisions and has been found to relate to prospective hearing aid use. Unlike objective measures of speech perception ability, ANL outcome is not related to individual hearing loss or age, but rather reflects an individual’s inherent acceptance of competing noise while listening to speech. As such, the measure may predict aspects of hearing aid success. Crucially, however, recent studies have questioned its repeatability (test–retest reliability). The first question for this study was whether the inconsistent results regarding the repeatability of the ANL test may be due to differences in speech material types used in previous studies. Second, it is unclear whether meaningfulness and semantic coherence of the speech modify ANL outcome. To investigate these questions, we compared ANLs obtained with three types of materials: the International Speech Test Signal (ISTS), which is non-meaningful and semantically non-coherent by definition, passages consisting of concatenated meaningful standard audiology sentences, and longer fragments taken from conversational speech. We included conversational speech as this type of speech material is most representative of everyday listening. Additionally, we investigated whether ANL outcomes, obtained with these three different speech materials, were associated with self-reported limitations due to hearing problems and listening effort in everyday life, as assessed by a questionnaire. ANL data were collected for 57 relatively good-hearing adult participants with an age range representative for hearing aid users. Results showed that meaningfulness, but not semantic coherence of the speech material affected ANL. Less noise was accepted for the non-meaningful ISTS signal than for the meaningful speech materials. ANL repeatability was comparable

  16. Intellectual property analysis of holographic materials business

    NASA Astrophysics Data System (ADS)

    Reingand, Nadya; Hunt, David

    2006-02-01

    The paper presents an overview of intellectual property in the field of holographic photosensitive materials and highlights the possibilities offered by patent searching and analysis. Thousands of patent documents relevant to holographic materials have been uncovered by the study. The search was performed in the following databases: U.S. Patent Office, European Patent Office, and Japanese Patent Office for the time frame of 1971 through November 2005. The patent analysis has unveiled trends in patent temporal distribution, leading IP portfolios, companies competition within the holographic materials market and other interesting insights.

  17. Electromagnetic properties of material coated surfaces

    NASA Technical Reports Server (NTRS)

    Beard, L.; Berrie, J.; Burkholder, R.; Dominek, A.; Walton, E.; Wang, N.

    1989-01-01

    The electromagnetic properties of material coated conducting surfaces were investigated. The coating geometries consist of uniform layers over a planar surface, irregularly shaped formations near edges and randomly positioned, electrically small, irregularly shaped formations over a surface. Techniques to measure the scattered field and constitutive parameters from these geometries were studied. The significance of the scattered field from these geometries warrants further study.

  18. Systems and methods for predicting materials properties

    DOEpatents

    Ceder, Gerbrand; Fischer, Chris; Tibbetts, Kevin; Morgan, Dane; Curtarolo, Stefano

    2007-11-06

    Systems and methods for predicting features of materials of interest. Reference data are analyzed to deduce relationships between the input data sets and output data sets. Reference data includes measured values and/or computed values. The deduced relationships can be specified as equations, correspondences, and/or algorithmic processes that produce appropriate output data when suitable input data is used. In some instances, the output data set is a subset of the input data set, and computational results may be refined by optionally iterating the computational procedure. To deduce features of a new material of interest, a computed or measured input property of the material is provided to an equation, correspondence, or algorithmic procedure previously deduced, and an output is obtained. In some instances, the output is iteratively refined. In some instances, new features deduced for the material of interest are added to a database of input and output data for known materials.

  19. Thermal Property Parameter Estimation of TPS Materials

    NASA Technical Reports Server (NTRS)

    Maddren, Jesse

    1998-01-01

    Accurate knowledge of the thermophysical properties of TPS (thermal protection system) materials is necessary for pre-flight design and post-flight data analysis. Thermal properties, such as thermal conductivity and the volumetric specific heat, can be estimated from transient temperature measurements using non-linear parameter estimation methods. Property values are derived by minimizing a functional of the differences between measured and calculated temperatures. High temperature thermal response testing of TPS materials is usually done in arc-jet or radiant heating facilities which provide a quasi one-dimensional heating environment. Last year, under the NASA-ASEE-Stanford Fellowship Program, my work focused on developing a radiant heating apparatus. This year, I have worked on increasing the fidelity of the experimental measurements, optimizing the experimental procedures and interpreting the data.

  20. How forest fire affects the chemical properties of Andisols

    NASA Astrophysics Data System (ADS)

    Neris, Jonay; Hernández-Moreno, José Manuel; Tejedor, Marisa; Jiménez, Concepción

    2013-04-01

    Forest fires affect soil physical, chemical and mineralogical properties. However, the magnitude of these changes depends on both fire properties, such as the peak temperature reached and duration or depth achieved; and initial soil properties (soil type) as for example soil moisture, organic matter content or soil structure characteristics. Although many works have studied the effects of fire on the chemical properties of different soil types, its effects on Andisols properties have been omitted until now. Taking into account the high susceptibility to drying processes showed by the properties of Andisols affected by land use changes, it could be expected that the fire effects on their chemical properties may differ from those shown by other types of soil. In this study, the main chemical properties in addition to the specific andic properties of burned pine forest Andisols were compared to their unburned control. The chemical properties of ashes found after fire at the soil surface were also studied. The results show a slightly increase in EC and pH after the fire due mainly to the higher content of cations of the soil solution. Ashes derived from the vegetation and soil organic matter consumption by fire could be the main source of these elements in the soils after a fire, as they showed a high cation content. However, the rise in EC and pH is lower than the reported by most authors for other soil types. This behaviour could be related to the higher organic matter content of this soils, even after fire, and the buffering effect of organic compounds on the soil EC and pH changes after the fire. As other authors have shown, a decrease in both the total and active organic content after the fire was also observed as a result of the fire event. The specific andic properties of Andisols were also affected. The P retention of these soils slightly declines as a consequence of fire, while the content of short-range-order products was also modified, but no statistically

  1. Properties of five toughened matrix composite materials

    NASA Technical Reports Server (NTRS)

    Cano, Roberto J.; Dow, Marvin B.

    1992-01-01

    The use of toughened matrix composite materials offers an attractive solution to the problem of poor damage tolerance associated with advanced composite materials. In this study, the unidirectional laminate strengths and moduli, notched (open-hole) and unnotched tension and compression properties of quasi-isotropic laminates, and compression-after-impact strengths of five carbon fiber/toughened matrix composites, IM7/E7T1-2, IM7/X1845, G40-800X/5255-3, IM7/5255-3, and IM7/5260 have been evaluated. The compression-after-impact (CAI) strengths were determined primarily by impacting quasi-isotropic laminates with the NASA Langley air gun. A few CAI tests were also made with a drop-weight impactor. For a given impact energy, compression after impact strengths were determined to be dependent on impactor velocity. Properties and strengths for the five materials tested are compared with NASA data on other toughened matrix materials (IM7/8551-7, IM6/1808I, IM7/F655, and T800/F3900). This investigation found that all five materials were stronger and more impact damage tolerant than more brittle carbon/epoxy composite materials currently used in aircraft structures.

  2. Tailoring of materials properties under extreme conditions

    NASA Astrophysics Data System (ADS)

    Schenkel, Thomas

    Materials can be driven far from equilibrium e. g. with intense pules of lasers and ions, in mostly destructive processes. When combined with micro- and nano-structuring, the ability to rapidly excite and then quench local excitations opens up. Now opportunities emerge to form and stabilize novel materials phases and to tailor materials properties for applications. Examples are color centers in diamond and silicon carbide for sensing and qubit applications and proposed ordered dopant structures in cuprate superconductors. Results from studies of materials processing under transient extreme conditions, far from equilibrium will be presented. This work was supported by the Director, Office of Science, Office of Fusion Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

  3. Effects of Material Properties on Bacterial Adhesion and Biofilm Formation.

    PubMed

    Song, F; Koo, H; Ren, D

    2015-08-01

    Adhesion of microbes, such as bacteria and fungi, to surfaces and the subsequent formation of biofilms cause multidrug-tolerant infections in humans and fouling of medical devices. To address these challenges, it is important to understand how material properties affect microbe-surface interactions and engineer better nonfouling materials. Here we review the recent progresses in this field and discuss the main challenges and opportunities. In particular, we focus on bacterial biofilms and review the effects of surface energy, charge, topography, and stiffness of substratum material on bacterial adhesion. We summarize how these surface properties influence oral biofilm formation, and we discuss the important findings from nondental systems that have potential applications in dental medicine. PMID:26001706

  4. First principles simulation of materials properties

    SciTech Connect

    Shelton, W.A.; Stocks, G.M.; Pinski, F.J.; Jordan, R.G.; Liu, Y.; Qui, L.L.; Staunton, J.B.; Johnson, D.D.; Ginatempo, B.

    1994-06-01

    We have developed a hybrid, parallel computer code for calculating the electronic structure of both ordered and substitutionally disordered materials. By using PVM3.3, we can integrate into our local computer environment multiple parallel and vector superconductors as well as high performance workstations. Without this approach, calculations of materials properties of large systems would be otherwise untenable due to a lack of computer resources. For example, we have determined the short-range order intensity and its electronic origin for the Ag-Mg alloy system, including an estimate of the order-disorder (spinodal) temperature.

  5. Temperature dependent phonon properties of thermoelectric materials

    NASA Astrophysics Data System (ADS)

    Hellman, Olle; Broido, David; Fultz, Brent

    2015-03-01

    We present recent developments using the temperature dependent effective potential technique (TDEP) to model thermoelectric materials. We use ab initio molecular dynamics to generate an effective Hamiltonian that reproduce neutron scattering spectra, thermal conductivity, phonon self energies, and heat capacities. Results are presented for (among others) SnSe, Bi2Te3, and Cu2Se proving the necessity of careful modelling of finite temperature properties for strongly anharmonic materials. Supported by the Swedish Research Council (VR) Project Number 637-2013-7296.

  6. First principles simulation of materials properties

    SciTech Connect

    Shelton, W.A.; Stocks, G.M.; Jordan, R.G.; Liu, Y.; Qui, L.; Johnson, D.D.; Pinski, F.J.; Staunton, J.B.; Ginatempo, B.

    1994-08-01

    We have developed a hybrid, parallel computer code for calculating the electronic structure of both ordered and substitutionally disordered materials. By using PVM3.3, we can integrate into our local computer environment multiple parallel and vector supercomputers as well as high performance workstations. Without this approach, calculations of materials properties of large systems would be otherwise untenable due to a lack of computer resources. For example, we have determined the short-range order intensity and its electronic origin for the Ag-Mg alloy system, including an estimate of the order-disorder (spinodal) temperature.

  7. 14 CFR 25.613 - Material strength properties and material design values.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... individual item is tested before use to determine that the actual strength properties of that particular item... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Material strength properties and material... § 25.613 Material strength properties and material design values. (a) Material strength properties...

  8. 14 CFR 25.613 - Material strength properties and material design values.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... individual item is tested before use to determine that the actual strength properties of that particular item... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Material strength properties and material... § 25.613 Material strength properties and material design values. (a) Material strength properties...

  9. 14 CFR 25.613 - Material strength properties and material design values.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... individual item is tested before use to determine that the actual strength properties of that particular item... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Material strength properties and material... § 25.613 Material strength properties and material design values. (a) Material strength properties...

  10. 14 CFR 25.613 - Material strength properties and material design values.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... individual item is tested before use to determine that the actual strength properties of that particular item... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Material strength properties and material... § 25.613 Material strength properties and material design values. (a) Material strength properties...

  11. 14 CFR 25.613 - Material strength properties and material design values.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... individual item is tested before use to determine that the actual strength properties of that particular item... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Material strength properties and material... § 25.613 Material strength properties and material design values. (a) Material strength properties...

  12. DIELECTRIC PROPERTIES OF VARIOUS NANOCOMPOSITE MATERIALS

    SciTech Connect

    Tuncer, E.; Polizos, G.; James, D. R.; Sauers, I.; Ellis, A. R.; More, K. L.

    2010-01-01

    Composite materials based on polymers are used in various engineering applications due to their ability to be tailored for a specific application. As a result a composite could be selected or designed for a high performance part such as field grading applications in high voltage technology. Presently, there exists no commercially available material for electric field control. For this reason in this study we characterize a polymeric system composed of a thermoplast polymer filled with nanometer size ceramic particles. Since it is hard to tailor or to predict properties of composites theoretically, an Edisonian approach is employed. Composites with different filler weight concentrations are prepared and their dielectric performance are characterized. Impedance spectroscopy technique at a constant frequency is used to determine the dielectric properties of the composites at low temperatures. Measurement results and potential applications of the composite systems are presented.

  13. Dielectric properties of various nanocomposite materials

    SciTech Connect

    Tuncer, Enis; Polyzos, Georgios; James, David Randy; Sauers, Isidor; Ellis, Alvin R; More, Karren Leslie

    2010-01-01

    Composite materials based on polymers are used in various engineering applications due to their ability to be tailored for a specific application. As a result a composite could be selected or designed for a high performance part such as field grading applications in high voltage technology. Presently, there exists no commercially available material for electric field control. For this reason in this study we characterize a polymeric system composed of a thermoplast polymer filled with nanometer size ceramic particles. Since it is hard to tailor or to predict properties of composites theoretically, an Edisonian approach is employed. Composites with different filler weight concentrations are prepared and their dielectric performance are characterized. Impedance spectroscopy technique at a constant frequency is used to determine the dielectric properties of the composites at low temperatures. Measurement results and potential applications of the composite systems are presented.

  14. Optical properties of photochromic and thermochromic materials

    NASA Astrophysics Data System (ADS)

    Mo, Yeon-Gon

    The optical properties of some thin film materials can be altered by an external stimulus. Photochromic and thermochromic materials, including inorganic and organic substances, have optical properties that can be changed in a reversible manner by irradiation and temperature respectively. These materials can be used in applications such as radiation or thermal sensors, information storage devices and smart window applications in buildings and cars. In this work, major effort was concentrated on passive thermal control coatings based on photochromic and thermochromic materials. The inorganic photochromic materials were based on tungsten and molybdenum oxide films and the organic photochromic materials included spiropyrans and spirooxazines. In addition, photochromic composite organic-inorganic films and thermochromic vanadium oxide films were prepared. The samples were synthesized using sputtering, sol-gel process, and thermal oxidation. The optical properties were investigated for the first time by ultraviolet/visible/infrared (UV/VIS/IR) spectroscopic ellipsometry, attenuated total reflection (ATR) infrared ellipsometry, spectrophotometry, and X-ray diffraction (XRD). For amorphous oxide films, the oxygen deficiency was important in determining the photochromic properties of the films. In the mid-infrared region, no photochromism was observed for the films. The optical properties of organic-inorganic composite films changed in the VIS/NIR wavelength region markedly in a reversible process, with UV irradiation. The composite films containing tungsten heteropolyoxometalate (HPOM) showed faster coloration and bleaching than pure tungsten oxide films. The composite films with molybdenum HPOM showed faster coloration and much slower bleaching than tungsten HPOM. The spiropyran and spirooxazine doped polymeric films were investigated for the first time using infrared and ATR ellipsometry. The infrared optical functions obtained by ATR measurements were a little smaller

  15. Solar Sail Material Performance Property Response to Space Environmental Effects

    NASA Technical Reports Server (NTRS)

    Edwards, David L.; Semmel, Charles; Hovater, Mary; Nehls, Mary; Gray, Perry; Hubbs, Whitney; Wertz, George

    2004-01-01

    The National Aeronautics and Space Administration's (NASA) Marshall Space Flight Center (MSFC) continues research into the utilization of photonic materials for spacecraft propulsion. Spacecraft propulsion, using photonic materials, will be achieved using a solar sail. A solar sail operates on the principle that photons, originating from the sun, impart pressure to the sail and therefore provide a source for spacecraft propulsion. The pressure imparted to a solar sail can be increased, up to a factor of two, if the sun-facing surface is perfectly reflective. Therefore, these solar sails are generally composed of a highly reflective metallic sun-facing layer, a thin polymeric substrate and occasionally a highly emissive back surface. Near term solar sail propelled science missions are targeting the Lagrange point 1 (Ll) as well as locations sunward of L1 as destinations. These near term missions include the Solar Polar Imager and the L1 Diamond. The Environmental Effects Group at NASA s Marshall Space Flight Center (MSFC) continues to actively characterize solar sail material in preparation for these near term solar sail missions. Previous investigations indicated that space environmental effects on sail material thermo-optical properties were minimal and would not significantly affect the propulsion efficiency of the sail. These investigations also indicated that the sail material mechanical stability degrades with increasing radiation exposure. This paper will further quantify the effect of space environmental exposure on the mechanical properties of candidate sail materials. Candidate sail materials for these missions include Aluminum coated Mylar[TM], Teonex[TM], and CPl (Colorless Polyimide). These materials were subjected to uniform radiation doses of electrons and protons in individual exposures sequences. Dose values ranged from 100 Mrads to over 5 Grads. The engineering performance property responses of thermo-optical and mechanical properties were

  16. Magnetic properties of Martian surface material

    NASA Technical Reports Server (NTRS)

    Hargraves, R. B.

    1984-01-01

    The hypothesis that the magnetic properties of the Martian surface material are due to the production of a magnetic phase in the clay mineral nontronite by transient shock heating is examined. In the course of the investigation a magnetic material is produced with rather unusual properties. Heating from 900 C to 1000 C, of natural samples of nontronite leads first to the production of what appears to be Si doped maghemite gamma (-Fe2O3). Although apparently metastable, the growth of gamma -Fe2O3 at these temprtures is unexpected, and its relative persistence of several hours at 1000 C is most surprising. Continued annealing of this material for longer periods promote the crystallization of alpha Fe2O3 and cristobalite (high temperature polymorph of SiO2). All available data correlate this new magnetic material with the cristobalite hence our naming it magnetic ferri cristobalite. Formation of this magnetic cristobalite, however, may require topotactic growth from a smectite precursor.

  17. Magnetic properties of Martian surface material

    NASA Astrophysics Data System (ADS)

    Hargraves, R. B.

    1984-06-01

    The hypothesis that the magnetic properties of the Martian surface material are due to the production of a magnetic phase in the clay mineral nontronite by transient shock heating is examined. In the course of the investigation a magnetic material is produced with rather unusual properties. Heating from 900 C to 1000 C, of natural samples of nontronite leads first to the production of what appears to be Si doped maghemite gamma (-Fe2O3). Although apparently metastable, the growth of gamma -Fe2O3 at these temprtures is unexpected, and its relative persistence of several hours at 1000 C is most surprising. Continued annealing of this material for longer periods promote the crystallization of alpha Fe2O3 and cristobalite (high temperature polymorph of SiO2). All available data correlate this new magnetic material with the cristobalite hence our naming it magnetic ferri cristobalite. Formation of this magnetic cristobalite, however, may require topotactic growth from a smectite precursor.

  18. Acoustical properties of highly porous fibrous materials

    NASA Technical Reports Server (NTRS)

    Lambert, R. F.

    1979-01-01

    Highly porous, fibrous bulk sound absorbing materials are studied with a view toward understanding their acoustical properties and performance in a wide variety of applications including liners of flow ducts. The basis and criteria for decoupling of acoustic waves in the pores of the frame and compressional waves in the frame structure are established. The equations of motion are recast in a form that elucidates the coupling mechanisms. The normal incidence surface impedance and absorption coefficient of two types of Kevlar 29 and an open celled foam material are studied. Experimental values and theoretical results are brought into agreement when the structure factor is selected to provide a fit to the experimental data. A parametric procedure for achieving that fit is established. Both a bulk material quality factor and a high frequency impedance level are required to characterize the real and imaginary part of the surface impedance and absorption coefficient. A derivation of the concepts of equivalent density and dynamic resistance is presented.

  19. Tailoring material properties of a nanofibrous extracellular matrix derived hydrogel

    NASA Astrophysics Data System (ADS)

    Johnson, Todd D.; Lin, Stephen Y.; Christman, Karen L.

    2011-12-01

    In the native tissue, the interaction between cells and the extracellular matrix (ECM) is essential for cell migration, proliferation, differentiation, mechanical stability, and signaling. It has been shown that decellularized ECMs can be processed into injectable formulations, thereby allowing for minimally invasive delivery. Upon injection and increase in temperature, these materials self-assemble into porous gels forming a complex network of fibers with nanoscale structure. In this study we aimed to examine and tailor the material properties of a self-assembling ECM hydrogel derived from porcine myocardial tissue, which was developed as a tissue specific injectable scaffold for cardiac tissue engineering. The impact of gelation parameters on ECM hydrogels has not previously been explored. We examined how modulating pH, temperature, ionic strength, and concentration affected the nanoscale architecture, mechanical properties, and gelation kinetics. These material characteristics were assessed using scanning electron microscopy, rheometry, and spectrophotometry, respectively. Since the main component of the myocardial matrix is collagen, many similarities between the ECM hydrogel and collagen gels were observed in terms of the nanofibrous structure and modulation of properties by altering ionic strength. However, variation from collagen gels was noted for the gelation temperature along with varied times and rates of gelation. These discrepancies when compared to collagen are likely due to the presence of other ECM components in the decellularized ECM based hydrogel. These results demonstrate how the material properties of ECM hydrogels could be tailored for future in vitro and in vivo applications.

  20. MATERIAL PROPERTIES OF COMMON SUTURE MATERIALS IN ORTHOPAEDIC SURGERY

    PubMed Central

    Najibi, S; Banglmeier, R; Matta, JM; Tannast, M

    2010-01-01

    Suture materials in orthopaedic surgery are used for closure of wounds, repair of fascia, muscles, tendons, ligaments, joint capsules, and cerclage or tension band of certain fractures. The purpose of this study was to compare the biomechanical properties of eleven commonly used sutures in orthopaedic surgery. Three types of braided non-absorbable and one type of braided absorbable suture material with different calibers (n=77) underwent biomechanical testing for maximum load to failure, strain, and stiffness. All samples were tied by one surgeon with a single SMC (Seoul Medical Center) knot and three square knots. The maximum load to failure and strain were highest for #5 FiberWire and lowest for #0 Ethibond Excel (p<0.001). The stiffness was highest for #5 FiberWire and lowest for #2-0 Vicryl (p<0.001). In all samples, the failure of the suture material occurred at the knot There was no slippage of the knot in any of the samples tested. This data will assist the orthopaedic surgeon in selection and application of appropriate suture materials and calibers to specific tasks. PMID:21045977

  1. Elastic properties of nanostructured materials with layered grain boundary structure

    NASA Astrophysics Data System (ADS)

    Karakasidis, T. E.; Charitidis, C. A.; Skarakis, D.; Chouliaras, F.

    2007-08-01

    Atomistic calculations of the elastic constants for a bulk nanostructured material that consists of a layered structure where alternating layers meet along high angle grain boundaries and where atoms interact via a Lennard-Jones potential are presented. The calculations of the elastic constants were performed in the frame of homogeneous deformations for a wide range of layer widths ranging from 2.24 up to 74.62 nm. The results showed that the relaxation of the atomic structure affects the elastic constants for the cases where more than 5% of atoms are located in the GB region. Also it was found that the way that external stresses are applied on the system affects the values of the obtained elastic properties, with the elastic constants related to the characteristic directions of the grain boundary being the most affected ones. The findings of this work are of interest for the fabrication methods of nanostructured materials, the measurement methods of their elastic properties as well as multiscale modeling schemes of nanostructured materials.

  2. Emergent Properties of Patch Shapes Affect Edge Permeability to Animals

    PubMed Central

    Nams, Vilis O.

    2011-01-01

    Animal travel between habitat patches affects populations, communities and ecosystems. There are three levels of organization of edge properties, and each of these can affect animals. At the lowest level are the different habitats on each side of an edge, then there is the edge itself, and finally, at the highest level of organization, is the geometry or structure of the edge. This study used computer simulations to (1) find out whether effects of edge shapes on animal behavior can arise as emergent properties solely due to reactions to edges in general, without the animals reacting to the shapes of the edges, and to (2) generate predictions to allow field and experimental studies to test mechanisms of edge shape response. Individual animals were modeled traveling inside a habitat patch that had different kinds of edge shapes (convex, concave and straight). When animals responded edges of patches, this created an emergent property of responding to the shape of the edge. The response was mostly to absolute width of the shapes, and not the narrowness of them. When animals were attracted to edges, then they tended to collect in convexities and disperse from concavities, and the opposite happened when animals avoided edges. Most of the responses occurred within a distance of 40% of the perceptual range from the tip of the shapes. Predictions were produced for directionality at various locations and combinations of treatments, to be used for testing edge behavior mechanisms. These results suggest that edge shapes tend to either concentrate or disperse animals, simply because the animals are either attracted to or avoid edges, with an effect as great as 3 times the normal density. Thus edge shape could affect processes like pollination, seed predation and dispersal and predator abundance. PMID:21747965

  3. The role of material properties in adhesion

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1984-01-01

    When two solid surfaces are brought into contact strong adhesive bond forces can develop between the materials. The magnitude of the forces will depend upon the state of the surfaces, cleanliness and the fundamental properties of the two solids, both surface and bulk. Adhesion between solids is addressed from a theoretical consideration of the electronic nature of the surfaces and experimentally relating bond forces to the nature of the interface resulting from solid state contact. Surface properties correlated with adhesion include, atomic or molecular orientation, reconstruction and segregation as well as the chemistry of the surface specie. Where dissimilar solids are in contact the contribution of each is considered as is the role of their interactive chemistry on bond strength. Bulk properties examined include elastic and plastic behavior in the surficial regions, cohesive binding energies, crystal structure, crystallographic orientation and state. Materials examined with respect to interfacial adhesive interactions include metals, alloys, ceramics, polymers and diamond. They are reviewed both in single and polycrystalline form. The surfaces of the contacting solids are studied both in the atomic or molecularly clean state and in the presence of selected surface contaminants.

  4. Mechanical properties of thermal protection system materials.

    SciTech Connect

    Hardy, Robert Douglas; Bronowski, David R.; Lee, Moo Yul; Hofer, John H.

    2005-06-01

    An experimental study was conducted to measure the mechanical properties of the Thermal Protection System (TPS) materials used for the Space Shuttle. Three types of TPS materials (LI-900, LI-2200, and FRCI-12) were tested in 'in-plane' and 'out-of-plane' orientations. Four types of quasi-static mechanical tests (uniaxial tension, uniaxial compression, uniaxial strain, and shear) were performed under low (10{sup -4} to 10{sup -3}/s) and intermediate (1 to 10/s) strain rate conditions. In addition, split Hopkinson pressure bar tests were conducted to obtain the strength of the materials under a relatively higher strain rate ({approx}10{sup 2} to 10{sup 3}/s) condition. In general, TPS materials have higher strength and higher Young's modulus when tested in 'in-plane' than in 'through-the-thickness' orientation under compressive (unconfined and confined) and tensile stress conditions. In both stress conditions, the strength of the material increases as the strain rate increases. The rate of increase in LI-900 is relatively small compared to those for the other two TPS materials tested in this study. But, the Young's modulus appears to be insensitive to the different strain rates applied. The FRCI-12 material, designed to replace the heavier LI-2200, showed higher strengths under tensile and shear stress conditions. But, under a compressive stress condition, LI-2200 showed higher strength than FRCI-12. As far as the modulus is concerned, LI-2200 has higher Young's modulus both in compression and in tension. The shear modulus of FRCI-12 and LI-2200 fell in the same range.

  5. MEASUREMENT OF MATERIAL PROPERTIES OF DAMAGED ENERGETIC MATERIALS

    SciTech Connect

    Hsu, P C; Hust, G; Dehaven, M; Chidester, S; Glascoe, L; Hoffman, M; Maienschein, J L

    2010-03-10

    We recently conducted damaged experiments on three explosives (mechanical damage on LX-04 and thermal experiments on HPP and PBXN-9) and characterized the effect of damage on some material properties. The MTS equipment was used to apply compressive cycling to LX-04 pressed parts and the results showed that older LX-04 parts became mechanically weaker than newer parts. After repeated compressive cycling for over 20,000 times, older LX-04 parts failed but newer LX-04 parts survived. Thermal insults were applied to PBXN-9 and HPP at 180 C and 200 C, respectively in unconfined conditions for several hours. The thermally-damaged HPP sample suffered 12.0% weight losses and a volume expansion of 20% was observed. Porosity of the damaged HPP increased to 25% after thermal exposure, which led to higher gas permeability. Burn rates of damaged PBXN-9 were 2 orders of magnitude higher than those of pristine samples but burn rates of damaged HPP were only slightly higher than those of pristine HPP. Small-scale safety tests (impact, friction, and spark) showed no significant sensitization when the damaged samples were tested at room temperature. Gas permeation measurements showed that gas permeability in damaged materials was several orders of magnitude higher than that in pristine materials. In-situ measurements of gas permeability at high temperatures were made on HPP samples and the results showed that the gas permeability increased by 3 to 4 orders of magnitude.

  6. Do Stretch Durations Affect Muscle Mechanical and Neurophysiological Properties?

    PubMed

    Opplert, J; Genty, J-B; Babault, N

    2016-08-01

    The aim of the study was to determine whether stretching durations influence acute changes of mechanical and neurophysiological properties of plantar flexor muscles. Plantar flexors of 10 active males were stretched in passive conditions on an isokinetic dynamometer. Different durations of static stretching were tested in 5 randomly ordered experimental trials (1, 2, 3, 4 and 10×30-s). Fascicle stiffness index, evoked contractile properties and spinal excitability (Hmax/Mmax) were examined before (PRE), immediately after (POST0) and 5 min after (POST5) stretching. No stretch duration effect was recorded for any variable. Moreover, whatever the stretching duration, stiffness index, peak twitch torque and rate of force development were significantly lower at POST0 and POST5 as compared to PRE (P<0.05). Electromechanical delay was longer at POST0 and POST5 as compared to PRE (P<0.05). Whatever the stretch duration, no significant changes of Hmax/Mmax ratio were recorded. In conclusion, 30 s of static stretching to maximum tolerated discomfort is sufficient enough to alter mechanical properties of plantar flexor muscles, but 10×30 s does not significantly affect these properties further. Stretching does not impair spinal excitability. PMID:27191211

  7. Physical Properties of Synthetic Resin Materials

    NASA Technical Reports Server (NTRS)

    Fishbein, Meyer

    1939-01-01

    A study was made to determine the physical properties of synthetic resins having paper, canvas, and linen reinforcements, and of laminated wood impregnated with a resin varnish. The results show that commercial resins have moduli of elasticity that are too low for structural considerations. Nevertheless, there do exist plastics that have favorable mechanical properties and, with further development, it should be possible to produce resin products that compare favorably with the light-metal alloys. The results obtained from tests on Compound 1840, resin-impregnated wood, show that this material can stand on its own merit by virtue of a compressive strength four times that of the natural wood. This increase in compressive strength was accomplished with an increase of density to a value slightly below three times the normal value and corrected one of the most serious defects of the natural product.

  8. Ferric Phosphate Hydroxide Microstructures Affect Their Magnetic Properties

    PubMed Central

    Zhao, Junhong; Zhang, Youjuan; Run, Zhen; Li, Pengwei; Guo, Qifei; Pang, Huan

    2015-01-01

    Uniformly sized and shape-controlled nanoparticles are important due to their applications in catalysis, electrochemistry, ion exchange, molecular adsorption, and electronics. Several ferric phosphate hydroxide (Fe4(OH)3(PO4)3) microstructures were successfully prepared under hydrothermal conditions. Using controlled variations in the reaction conditions, such as reaction time, temperature, and amount of hexadecyltrimethylammonium bromide (CTAB), the crystals can be grown as almost perfect hyperbranched microcrystals at 180 °C (without CTAB) or relatively monodisperse particles at 220 °C (with CTAB). The large hyperbranched structure of Fe4(OH)3(PO4)3 with a size of ∼19 μm forms with the “fractal growth rule” and shows many branches. More importantly, the magnetic properties of these materials are directly correlated to their size and micro/nanostructure morphology. Interestingly, the blocking temperature (TB) shows a dependence on size and shape, and a smaller size resulted in a lower TB. These crystals are good examples that prove that physical and chemical properties of nano/microstructured materials are related to their structures, and the precise control of the morphology of such functional materials could allow for the control of their performance. PMID:26246988

  9. Physical Properties of Thin Film Semiconducting Materials

    NASA Astrophysics Data System (ADS)

    Bouras, N.; Djebbouri, M.; Outemzabet, R.; Sali, S.; Zerrouki, H.; Zouaoui, A.; Kesri, N.

    2005-10-01

    The physics and chemistry of semiconducting materials is a continuous question of debate. We can find a large stock of well-known properties but at the same time, many things are not understood. In recent years, porous silicon (PS-Si), diselenide of copper and indium (CuInSe2 or CIS) and metal oxide semiconductors like tin oxide (SnO2) and zinc oxide (ZnO) have been subjected to extensive studies because of the rising interest their potential applications in fields such as electronic components, solar panels, catalysis, gas sensors, in biocompatible materials, in Li-based batteries, in new generation of MOSFETS. Bulk structure and surface and interface properties play important roles in all of these applications. A deeper understanding of these fundamental properties would impact largely on technological application performances. In our laboratory, thin films of undoped and antimony-doped films of tin oxide have been deposited by chemical vapor deposition. Spray pyrolysis was used for ZnO. CIS was prepared by flash evaporation or close-space vapor transport. Some of the deposition parameters have been varied, such as substrate temperature, time of deposition (or anodization), and molar concentration of bath preparation. For some samples, thermal annealing was carried out under oxygen (or air), under nitrogen gas and under vacuum. Deposition and post-deposition parameters are known to strongly influence film structure and electrical resistivity. We investigated the influence of film thickness and thermal annealing on structural optical and electrical properties of the films. Examination of SnO2 by x-ray diffraction showed that the main films are polycrystalline with rutile structure. The x-ray spectra of ZnO indicated a hexagonal wurtzite structure. Characterizations of CIS films with compositional analysis, x-ray diffraction, scanning microscopy, spectrophotometry, and photoluminescence were carried out.

  10. New Monolayered Materials Exhibiting Unusual Electronic Properties

    NASA Astrophysics Data System (ADS)

    Lopez-Bezanilla, Alejandro; Martin, Ivar; Littlewood, Peter B.

    Computationally based approaches are allowing to progress in the discovery and design of nano-scaled materials. Here we propose a series of new mono-layered compounds with exotic properties. By means of density functional theory calculations we demonstrate that the pentagonal arrangement of SiC2 yields an inverted distribution of the p-bands which leads to an unusual electronic behaviour of the material under strain [J. Phys. Chem. C, 2015, 119 (33), pp 19469]. A different pentagonal arrangement of C atoms enables the formation of Dirac cones which, unlike graphene, exhibit a strain-mediated tunable band gap. This work is supported by DOE-BES under Contract No. DE-AC02-06CH11357.

  11. Molybdenum silicide based materials and their properties

    SciTech Connect

    Yao, Z.; Stiglich, J.; Sudarshan, T.S.

    1999-06-01

    Molybdenum disilicide (MoSi{sub 2}) is a promising candidate material for high temperature structural applications. It is a high melting point (2030 C) material with excellent oxidation resistance and a moderate density (6.24 g/cm{sup 3}). However, low toughness at low temperatures and high creep rates at elevated temperatures have hindered its commercialization in structural applications. Much effort has been invested in MoSi{sub 2} composites as alternatives to pure molybdenum disilicide for oxidizing and aggressive environments. Molybdenum disilicide-based heating elements have been used extensively in high-temperature furnaces. The low electrical resistance of silicides in combination with high thermal stability, electron-migration resistance, and excellent diffusion-barrier characteristics is important for microelectronic applications. Projected applications of MoSi{sub 2}-based materials include turbine airfoils, combustion chamber components in oxidizing environments, missile nozzles, molten metal lances, industrial gas burners, diesel engine glow plugs, and materials for glass processing. On this paper, synthesis, fabrication, and properties of the monolithic and composite molybdenum silicides are reviewed.

  12. Auditory perception of geometry-invariant material properties.

    PubMed

    Ren, Zhimin; Yeh, Hengchin; Klatzky, Roberta; Lin, Ming C

    2013-04-01

    Accurately modeling the intrinsic material-dependent damping property for interactive sound rendering is a challenging problem. The Rayleigh damping model is commonly regarded as an adequate engineering model for interactive sound synthesis in virtual environment applications, but this assumption has never been rigorously analyzed. In this paper, we conduct a formal evaluation of this model. Our goal is to determine if auditory perception of material under Rayleigh damping assumption is 'geometry-invariant', i.e. if this approximation model is transferable across different shapes and sizes. First, audio recordings of same-material objects in various shapes and sizes are analyzed to determine if they can be approximated by the Rayleigh damping model with a single set of parameters. Next, we design and conduct a series of psychoacoustic experiments, in subjects evaluate if audio clips synthesized using the Rayleigh damping model are from the same material, when we alter the material, shape, and size parameters. Through both quantitative and qualitative evaluation, we show that the acoustic properties of the Rayleigh damping model for a single material is generally preserved across different geometries of objects consisting of homogeneous materials and is therefore a suitable, geometry-invariant sound model. Our study results also show that consistent with prior crossmodal expectations, visual perception of geometry can affect the auditory perception of materials. These findings facilitate the wide adoption of Rayleigh damping for interactive auditory systems and enable reuse of material parameters under this approximation model across different shapes and sizes, without laborious per-object parameter tuning. PMID:23428439

  13. Does UV irradiation affect polymer properties relevant to tissue engineering?

    NASA Astrophysics Data System (ADS)

    Fischbach, Claudia; Tessmar, Jörg; Lucke, Andrea; Schnell, Edith; Schmeer, Georg; Blunk, Torsten; Göpferich, Achim

    2001-10-01

    For most tissue engineering approaches aiming at the repair or generation of living tissues the interaction of cells and polymeric biomaterials is of paramount importance. Prior to contact with cells or tissues, biomaterials have to be sterilized. However, many sterilization procedures such as steam autoclave or heat sterilization are known to strongly affect polymer properties. UV irradiation is used as an alternative sterilization method in many tissue engineering laboratories on a routine basis, however, potential alterations of polymer properties have not been extensively considered. In this study we investigated the effects of UV irradiation on spin-cast films made from biodegradable poly( D, L-lactic acid)-poly(ethylene glycol)-monomethyl ether diblock copolymers (Me.PEG-PLA) which have recently been developed for controlled cell-biomaterial interaction. After 2 h of UV irradiation, which is sufficient for sterilization, no alterations in cell adhesion to polymer films were detected, as demonstrated with 3T3-L1 preadipocytes. This correlated with unchanged film topography and molecular weight distribution. However, extended UV irradiation for 5-24 h elicited drastic responses regarding Me.PEG-PLA polymer properties and interactions with biological elements: Large increases in unspecific protein adsorption and subsequent cell adhesion were observed. Changes in polymer surface properties could be correlated with the observed alterations in cell/protein-polymer interactions. Atomic force microscopy analysis of polymer films revealed a marked "smoothing" of the polymer surface after UV irradiation. Investigations using GPC, 1H-NMR, mass spectrometry, and a PEG-specific colorimetric assay demonstrated that polymer film composition was time-dependently affected by exposure to UV irradiation, i.e., that large amounts of PEG were lost from the copolymer surface. The data indicate that sterilization using UV irradiation for 2 h is an appropriate technique for the

  14. The effects of material property assumptions on predicted meltpool shape for laser powder bed fusion based additive manufacturing

    NASA Astrophysics Data System (ADS)

    Teng, Chong; Ashby, Kathryn; Phan, Nam; Pal, Deepankar; Stucker, Brent

    2016-08-01

    The objective of this study was to provide guidance on material specifications for powders used in laser powder bed fusion based additive manufacturing (AM) processes. The methodology was to investigate how different material property assumptions in a simulation affect meltpool prediction and by corrolary how different material properties affect meltpool formation in AM processes. The sensitvity of meltpool variations to each material property can be used as a guide to help drive future research and to help prioritize material specifications in requirements documents. By identifying which material properties have the greatest affect on outcomes, metrology can be tailored to focus on those properties which matter most; thus reducing costs by eliminating unnecessary testing and property charaterizations. Futhermore, this sensitivity study provides insight into which properties require more accurate measurements, thus motivating development of new metrology methods to measure those properties accurately.

  15. Tailoring material properties of sputtered beryllium

    SciTech Connect

    McEachern, R.M.

    1999-03-01

    Doped beryllium is a material of considerable interest to both the ICF and the weapons communities, as well as finding application in specialized industrial settings (e.g., x-ray windows and mirrors). Some of these uses require conformal coating of thin films on (possibly) irregularly-shaped surfaces. Physical vapor deposition (PVD) is often used to accomplish this, and sputtering is often the technique of choice. Among its advantages are that the depositing atoms are relatively energetic, leading to more compact films. Moreover, by simply applying a voltage bias to the substrate, ambient noble gas ions will bombard the growing film, which can cause further densification and other modifications to the microstructure. Sputtering is also well suited to the introduction of dopants, even those that are insoluble. Most applications of these novel materials will require fundamental knowledge of their properties. Because so many can be devised, such information is generally unavailable. The objective of the effort has been to systematically study the properties of films produced under different conditions, with an emphasis on surface finish and permeability. They have made extensive use of atomic force microscopy (AFM) and electron microscopy to determine the microstructure of the films, along with composition probes (mainly x-ray fluorescence) to quantify the chemical structure. The studies can be roughly divided into three categories. First, there are those in which the properties of pure or Cu-doped Be films have been investigated, especially on randomly-agitated spherical capsules. Included are studies of the effects of a constant substrate bias ranging from 0 to 120 v and application of an intermittent bias during deposition. Second, there are experiments in which the structure of the depositing films has been modified via the incorporation of dopants, primarily boron. Finally, there have been numerous attempts to characterize the permeability of Be coatings at

  16. Interdisciplinary research on the nature and properties of ceramic materials

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Several investigations concerning the properties and processing of brittle ceramic materials as related to design considerations are briefly described. Surface characterization techniques, fractography, high purity materials, creep properties, impact and thermal shock resistance, and reaction bonding are discussed.

  17. Viscoelastic properties and compaction behaviour of pharmaceutical particulate materials

    NASA Astrophysics Data System (ADS)

    Tsardaka, Ekaterini D.

    1990-01-01

    The viscoelastic behaviour of particulate solids is of major relevance in powder compaction. When designing a pharmaceutical tablet formulation, it is highly undesirable for the tablet properties to be markedly affected by changes in compaction rate on different tablet presses, if problems are to be avoided during scale-up and manufacture. In order to be able to predict and minimise the time-dependent deformation of pharmaceutical powders, a full understanding of such behaviour is needed. For comparative purposes, a range of materials with differing compaction properties were studied. Heckel plots were extended in order to study the consolidation behaviour of materials during compression, decompression and after ejection. A number of derived parameters were proposed as a useful means of assessing the viscoelastic characteristics of materials. The mechanical properties of the tablets produced were assessed by means of both a diametral loading test and a direct tension test, in order to study the homogeneity of tablets with respect to strength and toughness. Fitting stress relaxation data to a hyperbolic equation enabled the asymptotic value of relaxed stress and the rate of stress relaxation at short times to be determined. Creep analysis was found to be a most useful method in quantifying the viscoelastic properties of materials. Creep experiments were used to separately quantify the ability of a material to undergo elastic, viscoelastic and plastic deformation at constant stress. Analysis of the viscoelastic compliance provided a time constant and an equilibrium value. Spectral analysis of the creep data was an alternative method of studying viscoelastic behaviour, since analysis in the frequency domain revealed hidden periodicities of mechanisms possibly related to viscoelastic behaviour. A detailed study of several forms of modified starch addressed factors which may influence its viscoelastic behaviour, including manufacturing process variables such as particle

  18. Flexible control in processing affective and non-affective material predicts individual differences in trait resilience.

    PubMed

    Genet, Jessica J; Siemer, Matthias

    2011-02-01

    Trait resilience is a stable personality characteristic that involves the self-reported ability to flexibly adapt to emotional events and situations. The present study examined cognitive processes that may explain individual differences in trait resilience. Participants completed self-report measures of trait resilience, cognitive flexibility and working memory capacity tasks, and a novel affective task-switching paradigm that assesses the ability to flexibly switch between processing the affective versus non-affective qualities of affective stimuli (i.e., flexible affective processing). As hypothesised, cognitive flexibility and flexible affective processing were unique predictors of trait resilience. Working memory capacity was not predictive of trait resilience, indicating that trait resilience is tied to specific cognitive processes rather than overall better cognitive functioning. Cognitive flexibility and flexible affective processing were not associated with other trait measures, suggesting that these flexibility processes are unique to trait resilience. This study was among the first to investigate the cognitive abilities underlying trait resilience. PMID:21432680

  19. Food properties affecting the digestion and absorption of carbohydrates.

    PubMed

    Björck, I; Granfeldt, Y; Liljeberg, H; Tovar, J; Asp, N G

    1994-03-01

    Carbohydrate foods differ considerably in their effects on postprandial glucose and insulin responses. Qualitative differences among starchy foods are particularly intriguing because of the dominance of starch in human diets. This paper focuses on food properties in cereal (eg, pasta, bread, Arepas, and porridge) and legume products (eg, red kidney beans and lentils) that affect metabolic responses to starch. Studies in healthy subjects have found that postprandial blood glucose and insulin responses are greatly affected by food structure. Any process that disrupts the physical or botanical structure of food ingredients will increase the plasma glucose and insulin responses. The glycemic responses to bread products were reduced by the use of ingredients with an intact botanical or physical structure or a high amylose content or by enrichment with viscous dietary fiber. However, the important of a moderate increase in the amylose-amylopectin ratio and the naturally occurring levels of viscous cereal fiber is less clear. The rate of starch digestion in vitro was shown to be a key determinant of metabolic responses to most products. Assuming the sample preparation mimics chewing, in vitro enzymic procedures can be used to facilitate ranking. One such procedure, based on chewed rather than artificially disintegrated products, was recently developed and correlates well with glycemic and insulinemic indices for several starchy foods. PMID:8116553

  20. Spacecraft dielectric material properties and spacecraft charging

    NASA Technical Reports Server (NTRS)

    Frederickson, A. R.; Wall, J. A.; Cotts, D. B.; Bouquet, F. L.

    1986-01-01

    The physics of spacecraft charging is reviewed, and criteria for selecting and testing semiinsulating polymers (SIPs) to avoid charging are discussed and illustrated. Chapters are devoted to the required properties of dielectric materials, the charging process, discharge-pulse phenomena, design for minimum pulse size, design to prevent pulses, conduction in polymers, evaluation of SIPs that might prevent spacecraft charging, and the general response of dielectrics to space radiation. SIPs characterized include polyimides, fluorocarbons, thermoplastic polyesters, poly(alkanes), vinyl polymers and acrylates, polymers containing phthalocyanine, polyacene quinones, coordination polymers containing metal ions, conjugated-backbone polymers, and 'metallic' conducting polymers. Tables summarizing the results of SIP radiation tests (such as those performed for the NASA Galileo Project) are included.

  1. Characterization of Secondary Electron Emission Properties of Plasma Facing Materials

    NASA Astrophysics Data System (ADS)

    Patino, Marlene I.; Capece, Angela M.; Raitses, Yevgeny; Koel, Bruce E.

    2015-11-01

    The behavior of wall-bounded plasmas is significantly affected by the plasma-wall interactions, including the emission of secondary electrons (SEE) from the wall materials due to bombardment by primary electrons. The importance of SEE has prompted previous investigations of SEE properties of materials especially with applications to magnetic fusion, plasma thrusters, and high power microwave devices. In this work, we present results of measurements of SEE properties of graphite and lithium materials relevant for the divertor region of magnetic fusion devices. Measurements of total SEE yield (defined as the number of emitted secondary electrons per incident primary electron) for lithium are extended up to 5 keV primary electron energy, and the energy distributions of secondary electrons are provided for graphite and lithium. Additionally, the effect of contamination on the total SEE yield of lithium was explored by exposing the material to water vapor. Auger electron spectroscopy (AES) was used to determine surface composition and temperature programmed desorption (TPD) was used to determine lithium film thickness. Results show an order of magnitude increase in total SEE yield for lithium exposed to water vapor. This work was supported by DOE contract DE-AC02-09CH11466; AFOSR grants FA9550-14-1-0053, FA9550-11-1-0282, and AF9550-09-1-0695; and DOE Office of Science Graduate Student Research Program.

  2. Interdisciplinary research on the nature and properties of ceramic materials

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The advancement of material performance and design methodology as related to brittle materials was investigated. The processing and properties of ceramic materials as related to design requirements was also studied.

  3. Helium retention properties of plasma facing materials

    NASA Astrophysics Data System (ADS)

    Yanagihara, H.; Yamauchi, Y.; Hino, T.; Hirohata, Y.; Yamashina, T.

    1997-02-01

    In a fusion reactor, the continuous removal of helium from the core plasma is needed in order to sustain the ignition condition. For this purpose, it has been proposed to place helium selective pumping metals, which can trap more helium than hydrogen, in the vicinity of the divertor. In this study, the helium and hydrogen trapping properties of nickel, tungsten, molybdenum, SS 304 and Inconel 625 were examined. Namely, the dependencies of irradiation temperature on the amount of trapped helium and hydrogen were obtained by thermal desorption spectroscopy (TDS), after helium or hydrogen plasma irradiation. In those metals, nickel showed the most suitable selective pumping capability. Nickel had the helium selective pumping property above 100°C. The maximum amount of trapped helium was (2-3) × 10 16He/ cm2 at an irradiation temperature of 200°C and 600°C. The optimum temperature becomes about 600°C when nickel is used for a selective pumping material.

  4. Mechanical properties of low dimensional materials

    NASA Astrophysics Data System (ADS)

    Saini, Deepika

    Recent advances in low dimensional materials (LDMs) have paved the way for unprecedented technological advancements. The drive to reduce the dimensions of electronics has compelled researchers to devise newer techniques to not only synthesize novel materials, but also tailor their properties. Although micro and nanomaterials have shown phenomenal electronic properties, their mechanical robustness and a thorough understanding of their structure-property relationship are critical for their use in practical applications. However, the challenges in probing these mechanical properties dramatically increase as their dimensions shrink, rendering the commonly used techniques inadequate. This dissertation focuses on developing techniques for accurate determination of elastic modulus of LDMs and their mechanical responses under tensile and shear stresses. Fibers with micron-sized diameters continuously undergo tensile and shear deformations through many phases of their processing and applications. Significant attention has been given to their tensile response and their structure-tensile properties relations are well understood, but the same cannot be said about their shear responses or the structure-shear properties. This is partly due to the lack of appropriate instruments that are capable of performing direct shear measurements. In an attempt to fill this void, this dissertation describes the design of an inexpensive tabletop instrument, referred to as the twister, which can measure the shear modulus (G) and other longitudinal shear properties of micron-sized individual fibers. An automated system applies a pre-determined twist to the fiber sample and measures the resulting torque using a sensitive optical detector. The accuracy of the instrument was verified by measuring G for high purity copper and tungsten fibers. Two industrially important fibers, IM7 carbon fiber and KevlarRTM 119, were found to have G = 17 and 2.4 GPa, respectively. In addition to measuring the shear

  5. Solar Sail Material Performance Property Response to Space Environmental Effects

    NASA Technical Reports Server (NTRS)

    Edwards, David L.; Semmel, Charles; Hovater, Mary; Nehls, Mary; Gray, Perry; Hubbs, Whitney; Wertz, George

    2004-01-01

    The National Aeronautics and Space Administration's (NASA) Marshall Space Flight Center (MSFC) continues research into the utilization of photonic materials for spacecraft propulsion. Spacecraft propulsion, using photonic materials, will be achieved using a solar sail. A solar sail operates on the principle that photons, originating from the sun, impart pressure to the sail and therefore provide a source for spacecraft propulsion. The pressure imparted to a solar sail can be increased, up to a factor of two if the sun-facing surface is perfectly reflective. Therefore, these solar sails are generally composed of a highly reflective metallic sun-facing layer, a thin polymeric substrate and occasionally a highly emissive back surface. Near term solar sail propelled science missions are targeting the Lagrange point 1 (L1) as well as locations sunward of L1 as destinations. These near term missions include the Solar Polar Imager' and the L1 Diamond '. The Environmental Effects Group at NASA's Marshall Space Fliglit Center (MSFC) continues to actively characterize solar sail material in preparation for these near term solar sail missions. Previous investigations indicated that space environmental effects on sail material thermo-optical properties were minimal and would not significantly affect the propulsion efficiency of the sail3-'. These investigations also indicated that the sail material mechanical stability degrades with increasing radiation exposure. This paper will further quantify the effect of space environmental exposure on the mechanical properties of candidate sail materials. Candidate sail materials for these missions include Aluminum coated Mylar TM, Teonexm, and CP1 (Colorless Polyimide). These materials were subjected to uniform radiation doses of electrons and protons in individual exposures sequences. Dose values ranged from 100 Mrads to over 5 Grads. The engineering performance property responses of thermo-optical and mechanical properties were

  6. Environmental Factors Affecting the Permanence of Library Materials

    ERIC Educational Resources Information Center

    Wessel, Carl J.

    1970-01-01

    Reviews pertinent evidence relating to deterioration originating with air pollution, heat, humidity, light, and biological agents; and suggests how librarians may lengthen the useful life of library materials through environmental controls. (Author/JS)

  7. Maternal nutrient restriction affects properties of skeletal muscle in offspring

    PubMed Central

    Zhu, Mei J; Ford, Stephen P; Means, Warrie J; Hess, Bret W; Nathanielsz, Peter W; Du, Min

    2006-01-01

    Maternal nutrient restriction (NR) affects fetal development with long-term consequences on postnatal health of offspring, including predisposition to obesity and diabetes. Most studies have been conducted in fetuses in late gestation, and little information is available on the persistent impact of NR from early to mid-gestation on properties of offspring skeletal muscle, which was the aim of this study. Pregnant ewes were subjected to 50% NR from day 28–78 of gestation and allowed to deliver. The longissimus dorsi muscle was sampled from 8-month-old offspring. Maternal NR during early to mid-gestation decreased the number of myofibres in the offspring and increased the ratio of myosin IIb to other isoforms by 17.6 ± 4.9% (P < 0.05) compared with offspring of ad libitum fed ewes. Activity of carnitine palmitoyltransferase-1, a key enzyme controlling fatty acid oxidation, was reduced by 24.7 ± 4.5% (P < 0.05) in skeletal muscle of offspring of NR ewes and would contribute to increased fat accumulation observed in offspring of NR ewes. Intramuscular triglyceride content (IMTG) was increased in skeletal muscle of NR lambs, a finding which may be linked to predisposition to diabetes in offspring of NR mothers, since enhanced IMTG predisposes to insulin resistance in skeletal muscle. Proteomic analysis by two-dimensional gel electrophoresis demonstrated downregulation of several catabolic enzymes in 8-month-old offspring of NR ewes. These data demonstrate that the early to mid-gestation period is important for skeletal muscle development. Impaired muscle development during this stage of gestation affects the number and composition of fibres in offspring which may lead to long-term physiological consequences, including predisposition to obesity and diabetes. PMID:16763001

  8. The Study of the Thermoelectric Properties of Phase Change Materials

    NASA Astrophysics Data System (ADS)

    Yin, Ming; Abdi, Mohammed; Noimande, Zibusisu; Mbamalu, Godwin; Alameeri, Dheyaa; Datta, Timir

    We study thermoelectric property that is electrical phenomena occurring in conjunction with the flow of heat of phase-change materials (PCM) in particular GeSbTe (GST225). From given sets of material parameters, COMSOL Multiphysics heat-transfer module is used to compute maps of temperature and voltage distribution in the PCM samples. These results are used to design an apparatus including the variable temperature sample holder set up. An Arbitrary/ Function generator and a circuit setup is also designed to control the alternation of heaters embedded on the sample holder in order to ensure sequential back and forward flow of heat current from both sides of the sample. Accurate values of potential differences and temperature distribution profiles are obtained in order to compute the Seebeck coefficient of the sample. The results of elemental analysis and imaging studies such as XRD, UV-VIS, EDEX and SEM of the sample are obtained. Factors affecting the thermoelectric properties of phase change memory are also discussed. NNSA/ DOD Consortium for Materials and Energy Studies.

  9. Happy Objects, Happy Men? Affect and Materiality in Vocational Training

    ERIC Educational Resources Information Center

    Åberg, Magnus; Hedlin, Maria

    2015-01-01

    This article investigates the prevailing social inertia of vocational training. Previous research indicates that gendered social norms contribute to sustaining gender segregation. Few studies, however, have paid attention to how the interplay of emotional and material factors impact on gender norms in vocational training. The article builds on an…

  10. Properties of materials using acoustic waves

    NASA Astrophysics Data System (ADS)

    Apfel, R. E.

    1984-10-01

    Our goal of characterizing materials using acoustic waves was forwarded through a number of projects: (1) We have refined our modulated radiation pressure technique for characterizing the interfaces between liquids so that we can automatically track changes in interfacial tension over time due to contaminants, surfactants, etc. (2) We have improved and simplified our acoustic scattering apparatus for measuring distributions of the properties of microparticle samples, which will allow us to distinguish particulates in liquids by size, compressibility, and density. (3) We are continuing work on theoretical approaches to nonlinear acoustics which should permit us to cast problems with geometric and other complexities into a manageable form. (4) Our studies of cavitation have enabled us to derive an analytic expression which predicts the acoustic pressure threshold for cavitation at the micrometer scale - where surface tension effects are important. This work has relevance to the consideration of possible bioeffects from diagnostic ultrasound. (5) Other projects include the calibration of hydrophones using acoustically levitated samples, and the investigation of solitary waves of the sort discovered by Wu, Keolian and Rudnick.

  11. Factors Influencing the Dielectric Properties of Agricultural and Food Materials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dielectric properties of materials are defined, and the major factors that influence these properties of agricultural and food materials, namely, frequency of the applied radio-frequency or microwave electric fields, and water content, temperature, and density of the materials, are discussed on the ...

  12. Mechanical properties of new dental pulp-capping materials.

    PubMed

    Nielsen, Matthew J; Casey, Jeffery A; VanderWeele, Richard A; Vandewalle, Kraig S

    2016-01-01

    The mechanical properties of pulp-capping materials may affect their resistance to fracture during placement of a final restorative material or while supporting an overlying restoration over time. The purpose of this study was to compare the compressive strength, flexural strength, and flexural modulus of 2 new pulp-capping materials (TheraCal LC and Biodentine), mineral trioxide aggregate (MTA), and calcium hydroxide over time. Specimens were created in molds and tested to failure in a universal testing machine after 15 minutes, 3 hours, and 24 hours. The MTA specimens did not set at 15 minutes. At all time periods, TheraCal LC had the greatest compressive and flexural strengths. After 3 and 24 hours, Biodentine had the greatest flexural modulus. TheraCal LC had greater early strength to potentially resist fracture during immediate placement of a final restorative material. Biodentine had greater stiffness after 3 hours to potentially provide better support of an overlying restoration under function over time. PMID:26742167

  13. How vision affects kinematic properties of pantomimed prehension movements.

    PubMed

    Fukui, Takao; Inui, Toshio

    2013-01-01

    When performing the reach-to-grasp movement, fingers open wider than the size of a target object and then stop opening. The recorded peak grip aperture (PGA) is significantly larger when this action is performed without vision during the movement than with vision, presumably due to an error margin that is retained in order to avoid collision with the object. People can also pretend this action based on an internal target representation (i.e., pantomimed prehension), and previous studies have shown that kinematic differences exist between natural and pantomimed prehension. These differences are regarded as a reflection of variations in information processing in the brain through the dorsal and ventral streams. Pantomimed action is thought to be mediated by the ventral stream. This implies that visual information during the movement, which is essential to the dorsal stream, has little effect on the kinematic properties of pantomimed prehension. We investigated whether an online view of the external world affects pantomimed grasping, and more specifically, whether the dorsal stream is involved in its execution. Participants gazed at a target object and were then subjected to a 3-s visual occlusion, during which time the experimenter removed the object. The participants were then required to pretend to make a reach-to-grasp action toward the location where the object had been presented. Two visual conditions (full vision and no vision) were imposed during the pantomimed action by manipulating shutter goggles. The PGA showed significant differences between the two visual conditions, whereas no significant difference was noted for terminal grip aperture, which was recorded at the movement end. This suggests the involvement of the dorsal stream in pantomimed action and implies that pantomimed prehension is a good probe for revealing the mechanism of interaction between the ventral and dorsal streams, which is also linked to embodied cognition. PMID:23404470

  14. 7 CFR 1955.105 - Real property affected (CONACT).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... planting, cultivating, growing, producing, harvesting, or storing a controlled substance (see 21 CFR Part... AGRICULTURE (CONTINUED) PROGRAM REGULATIONS (CONTINUED) PROPERTY MANAGEMENT Disposal of Inventory Property... and Waste Disposal (WWD); Reserve Conservation and Development (RC&D); Watershed (WS);...

  15. Water Bouncing Balls: how material stiffness affects water entry

    NASA Astrophysics Data System (ADS)

    Truscott, Tadd

    2014-03-01

    It is well known that one can skip a stone across the water surface, but less well known that a ball can also be skipped on water. Even though 17th century ship gunners were aware that cannonballs could be skipped on the water surface, they did not know that using elastic spheres rather than rigid ones could greatly improve skipping performance (yet would have made for more peaceful volleys). The water bouncing ball (Waboba®) is an elastic ball used in a game of aquatic keep away in which players pass the ball by skipping it along the water surface. The ball skips easily along the surface creating a sense that breaking the world record for number of skips could easily be achieved (51 rock skips Russell Byers 2007). We investigate the physics of skipping elastic balls to elucidate the mechanisms by which they bounce off of the water. High-speed video reveals that, upon impact with the water, the balls create a cavity and deform significantly due to the extreme elasticity; the flattened spheres resemble skipping stones. With an increased wetted surface area, a large hydrodynamic lift force is generated causing the ball to launch back into the air. Unlike stone skipping, the elasticity of the ball plays an important roll in determining the success of the skip. Through experimentation, we demonstrate that the deformation timescale during impact must be longer than the collision time in order to achieve a successful skip. Further, several material deformation modes can be excited upon free surface impact. The effect of impact velocity and angle on the two governing timescales and material wave modes are also experimentally investigated. Scaling for the deformation and collision times are derived and used to establish criteria for skipping in terms of relevant physical parameters.

  16. Understanding nanoscale mechanical properties of materials using ultrafast EUV photoacoustics

    NASA Astrophysics Data System (ADS)

    Hoogeboom-Pot, K.; Turgut, E.; Shaw, J.; Hernandez-Charpak, J.; Murnane, M.; Kapteyn, H.; Nardi, D.

    2014-03-01

    How do the elastic properties of materials evolve as a nanostructure builds up layer by layer? A host of questions in nanoscience, nanotechnology, quantum dot systems and more rely on an answer to this issue; but our ability to probe mechanical properties is severely constrained at dimensions below 100 nm. With tabletop high harmonic generation (HHG), we overcome these limitations by extending non-destructive visible photoacoustics to extreme ultraviolet (EUV) wavelengths. The short wavelength of EUV light, combined with the coherence and ultrashort pulses of HHG creates a unique and powerful probe of nanostructured materials on their intrinsic length and time scales. We study a series of ultrathin bilayer (10-nm Ni/0-6-nm Ta) nanostructures on SiO2 substrates. A femtosecond infrared pulse excites longitudinal acoustic waves (LAWs) within the nanostructures and surface acoustic waves (SAWs) in the substrate. Diffraction of a time-delayed EUV probe pulse monitors the dynamics. LAW resonances are directly related to the bilayer thickness and effective speed of sound; their dependence on Ta-layer thickness reveals that the LAW velocities of both Ni and Ta differ from bulk values. The changing mass of Ta also affects the SAW frequency, allowing us to extract nanoscale densities. This work was supported by the SRC Contract 2012-OJ-2304, by NSF Award No.: DGE 1144083, and used facilities provided by the NSF Engineering Research Center in EUV Science and Technology.

  17. Line defects in graphene: How doping affects the electronic and mechanical properties

    NASA Astrophysics Data System (ADS)

    Berger, Daniel; Ratsch, Christian

    2016-06-01

    Graphene and carbon nanotubes have extraordinary mechanical and electronic properties. Intrinsic line defects such as local nonhexagonal reconstructions or grain boundaries, however, significantly reduce the tensile strength, but feature exciting electronic properties. Here, we address the properties of line defects in graphene from first principles on the level of full-potential density-functional theory, and assess doping as one strategy to strengthen such materials. We carefully disentangle the global and local effect of doping by comparing results from the virtual crystal approximation with those from local substitution of chemical species, in order to gain a detailed understanding of the breaking and stabilization mechanisms. We find that doping primarily affects the occupation of the frontier orbitals. Occupation through n -type doping or local substitution with nitrogen increases the ultimate tensile strength significantly. In particular, it can stabilize the defects beyond the ultimate tensile strength of the pristine material. We therefore propose this as a key strategy to strengthen graphenic materials. Furthermore, we find that doping and/or applying external stress lead to tunable and technologically interesting metal/semiconductor transitions.

  18. Perception of the material properties of wood based on vision, audition, and touch.

    PubMed

    Fujisaki, Waka; Tokita, Midori; Kariya, Kenji

    2015-04-01

    Most research on the multimodal perception of material properties has investigated the perception of material properties of two modalities such as vision-touch, vision-audition, audition-touch, and vision-action. Here, we investigated whether the same affective classifications of materials can be found in three different modalities of vision, audition, and touch, using wood as the target object. Fifty participants took part in an experiment involving the three modalities of vision, audition, and touch, in isolation. Twenty-two different wood types including genuine, processed, and fake were perceptually evaluated using a questionnaire consisting of twenty-three items (12 perceptual and 11 affective). The results demonstrated that evaluations of the affective properties of wood were similar in all three modalities. The elements of "expensiveness, sturdiness, rareness, interestingness, and sophisticatedness" and "pleasantness, relaxed feelings, and liked-disliked" were separately grouped for all three senses. Our results suggest that the affective material properties of wood are at least partly represented in a supramodal fashion. Our results also suggest an association between perceptual and affective properties, which will be a useful tool not only in science, but also in applied fields. PMID:25576379

  19. Magnetic properties of frictional volcanic materials

    NASA Astrophysics Data System (ADS)

    Kendrick, Jackie E.; Lavallée, Yan; Biggin, Andrew; Ferk, Annika; Leonhardt, Roman

    2015-04-01

    During dome-building volcanic eruptions, highly viscous magma extends through the upper conduit in a solid-like state. The outer margins of the magma column accommodate the majority of the strain, while the bulk of the magma is able to extrude, largely undeformed, to produce magma spines. Spine extrusion is often characterised by the emission of repetitive seismicity, produced in the upper <1 km by magma failure and slip at the conduit margins. The rheology of the magma controls the depth at which fracture can occur, while the frictional properties of the magma are important in controlling subsequent marginal slip processes. Upon extrusion, spines are coated by a carapace of volcanic fault rocks which provide insights into the deeper conduit processes. Frictional samples from magma spines at Mount St. Helens (USA), Soufriere Hills (Montserrat) and Mount Unzen (Japan) have been examined using structural, thermal and magnetic analyses to reveal a history of comminution, frictional heating, melting and cooling to form volcanic pseudotachylyte. Pseudotachylyte has rarely been noted in volcanic materials, and the recent observation of its syn-eruptive formation in dome-building volcanoes was unprecedented. The uniquely high thermal conditions of volcanic environments means that frictional melt remains at elevated temperatures for longer than usual, causing slow crystallisation, preventing the development of some signature "quench" characteristics. As such, rock-magnetic tests have proven to be some of the most useful tools in distinguishing pseudotachylytes from their andesite/ dacite hosts. In volcanic pseudotachylyte the mass normalised natural remanent magnetisation (NRM) when further normalised with the concentration dependent saturation remanence (Mrs) was found to be higher than the host rock. Remanence carriers are defined as low coercive materials across all samples, and while the remanence of the host rock displays similarities to an anhysteretic remanent

  20. Cytocompatibility and antibacterial properties of capping materials.

    PubMed

    Poggio, Claudio; Arciola, Carla Renata; Beltrami, Riccardo; Monaco, Annachiara; Dagna, Alberto; Lombardini, Marco; Visai, Livia

    2014-01-01

    The aim of this study was to evaluate and compare the antimicrobial activity and cytocompatibility of six different pulp-capping materials: Dycal (Dentsply), Calcicur (Voco), Calcimol LC (Voco), TheraCal LC (Bisco), MTA Angelus (Angelus), and Biodentine (Septodont). To evaluate antimicrobial activity, materials were challenged in vitro with Streptococcus mutans, Streptococcus salivarius, and Streptococcus sanguis in the agar disc diffusion test. Cytocompatibility of the assayed materials towards rat MDPC-23 cells was evaluated at different times by both MTT and apoptosis assays. Results significantly differed among the different materials tested. Both bacterial growth inhibition halos and cytocompatibility performances were significantly different among materials with different composition. MTA-based products showed lower cytotoxicity and valuable antibacterial activity, different from calcium hydroxide-based materials, which exhibited not only higher antibacterial activity but also higher cytotoxicity. PMID:24959601

  1. Cytocompatibility and Antibacterial Properties of Capping Materials

    PubMed Central

    Arciola, Carla Renata; Monaco, Annachiara; Lombardini, Marco

    2014-01-01

    The aim of this study was to evaluate and compare the antimicrobial activity and cytocompatibility of six different pulp-capping materials: Dycal (Dentsply), Calcicur (Voco), Calcimol LC (Voco), TheraCal LC (Bisco), MTA Angelus (Angelus), and Biodentine (Septodont). To evaluate antimicrobial activity, materials were challenged in vitro with Streptococcus mutans, Streptococcus salivarius, and Streptococcus sanguis in the agar disc diffusion test. Cytocompatibility of the assayed materials towards rat MDPC-23 cells was evaluated at different times by both MTT and apoptosis assays. Results significantly differed among the different materials tested. Both bacterial growth inhibition halos and cytocompatibility performances were significantly different among materials with different composition. MTA-based products showed lower cytotoxicity and valuable antibacterial activity, different from calcium hydroxide-based materials, which exhibited not only higher antibacterial activity but also higher cytotoxicity. PMID:24959601

  2. Absorption properties of waste matrix materials

    SciTech Connect

    Briggs, J.B.

    1997-06-01

    This paper very briefly discusses the need for studies of the limiting critical concentration of radioactive waste matrix materials. Calculated limiting critical concentration values for some common waste materials are listed. However, for systems containing large quantities of waste materials, differences up to 10% in calculated k{sub eff} values are obtained by changing cross section data sets. Therefore, experimental results are needed to compare with calculation results for resolving these differences and establishing realistic biases.

  3. Studies of molecular properties of polymeric materials

    NASA Technical Reports Server (NTRS)

    Harries, W. L.; Long, Sheila Ann T.; Long, Edward R., Jr.

    1990-01-01

    Aerospace environment effects (high energy electrons, thermal cycling, atomic oxygen, and aircraft fluids) on polymeric and composite materials considered for structural use in spacecraft and advanced aircraft are examined. These materials include Mylar, Ultem, and Kapton. In addition to providing information on the behavior of the materials, attempts are made to relate the measurements to the molecular processes occurring in the material. A summary and overview of the technical aspects are given along with a list of the papers that resulted from the studies. The actual papers are included in the appendices and a glossary of technical terms and definitions is included in the front matter.

  4. Metallurgy and properties of plasma spray formed materials

    NASA Technical Reports Server (NTRS)

    Mckechnie, T. N.; Liaw, Y. K.; Zimmerman, F. R.; Poorman, R. M.

    1992-01-01

    Understanding the fundamental metallurgy of vacuum plasma spray formed materials is the key to enhancing and developing full material properties. Investigations have shown that the microstructure of plasma sprayed materials must evolve from a powder splat morphology to a recrystallized grain structure to assure high strength and ductility. A fully, or near fully, dense material that exhibits a powder splat morphology will perform as a brittle material compared to a recrystallized grain structure for the same amount of porosity. Metallurgy and material properties of nickel, iron, and copper base alloys will be presented and correlated to microstructure.

  5. Ultrasonic excitation affects friction interactions between food materials and cutting tools.

    PubMed

    Schneider, Yvonne; Zahn, Susann; Schindler, Claudia; Rohm, Harald

    2009-06-01

    In the food industry, ultrasonic cutting is used to improve separation by a reduction of the cutting force. This reduction can be attributed to the modification of tool-workpiece interactions at the cutting edge and along the tool flanks because of the superposition of the cutting movement with ultrasonic vibration of the cutting tool. In this study, model experiments were used to analyze friction between the flanks of a cutting tool and the material to be cut. Friction force at a commercial cutting sonotrode was quantified using combined cutting-friction experiments, and sliding friction tests were carried out by adapting a standard draw-off assembly and using an ultrasonic welding sonotrode as sliding surface. The impact of material parameters, ultrasonic amplitude, and the texture of the contacting food surface on friction force was investigated. The results show that ultrasonic vibration significantly reduces the sliding friction force. While the amplitude showed no influence within the tested range, the texture of the contact surface of the food affects the intensity of ultrasonic transportation effects. These effects are a result of mechanical interactions and of changes in material properties of the contact layer, which are induced by the deformation of contact points, friction heating and absorption heating because of the dissipation of mechanical vibration energy. PMID:19342070

  6. NDE Elastic Properties of Fiber-Reinforced Composite Materials

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Y.

    1995-01-01

    Fiber-reinforced composites are increasingly replacing metallic alloys as structural materials for primary components of fracture-critical structures. This trend is a result of the growing understanding of material behavior and recognition of the desirable properties of composites. A research program was conducted on NDE methods for determining the elastic properties of composites.

  7. Dielectric properties of agricultural materials and their application

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This book is prepared as a comprehensive source of information on dielectric properties of agricultural materials for scientific researchers and engineers involved in practical application of radio-frequency and microwave energy for potential problem solutions. Dielectric properties of materials det...

  8. Structure and Thermal Properties of Porous Geological Materials

    NASA Astrophysics Data System (ADS)

    Kirk, Simon; Williamson, David

    2011-06-01

    Understanding the behaviour of porous geological materials is important for developing models of the explosive loading of rock in mining applications. To this end it is essential to first characterise its complex internal structure. Knowing the structure shows how the properties of the component materials relate to the overall properties of rock. The structure and mineralogy of Gosford sandstone was investigated and this information was used to predict its thermal properties. The thermal properties of the material were measured experimentally and compared against these predictions.

  9. Exposure effects on the optical properties of building materials

    NASA Astrophysics Data System (ADS)

    Lane, Sarah; Cathcart, J. Michael; Harrell, J. Timothy

    2008-04-01

    Georgia Tech recently initiated a weathering effects measurement program to monitor the optical properties of several common building materials. A set of common building materials were placed outdoors and optical property measurements made over a series of weeks to assess the impact of exposure on these properties. Both reflectivity and emissivity measurements were made. Materials in this program included aluminum flashing, plastic sheets, bricks, roof shingles, and tarps. This paper will discuss the measurement approach, experimental setup, and present preliminary results from the optical property measurements.

  10. Calculation of material properties and ray tracing in transformation media.

    PubMed

    Schurig, D; Pendry, J B; Smith, D R

    2006-10-16

    Complex and interesting electromagnetic behavior can be found in spaces with non-flat topology. When considering the properties of an electromagnetic medium under an arbitrary coordinate transformation an alternative interpretation presents itself. The transformed material property tensors may be interpreted as a different set of material properties in a flat, Cartesian space. We describe the calculation of these material properties for coordinate transformations that describe spaces with spherical or cylindrical holes in them. The resulting material properties can then implement invisibility cloaks in flat space. We also describe a method for performing geometric ray tracing in these materials which are both inhomogeneous and anisotropic in their electric permittivity and magnetic permeability. PMID:19529371

  11. "TPSX: Thermal Protection System Expert and Material Property Database"

    NASA Technical Reports Server (NTRS)

    Squire, Thomas H.; Milos, Frank S.; Rasky, Daniel J. (Technical Monitor)

    1997-01-01

    The Thermal Protection Branch at NASA Ames Research Center has developed a computer program for storing, organizing, and accessing information about thermal protection materials. The program, called Thermal Protection Systems Expert and Material Property Database, or TPSX, is available for the Microsoft Windows operating system. An "on-line" version is also accessible on the World Wide Web. TPSX is designed to be a high-quality source for TPS material properties presented in a convenient, easily accessible form for use by engineers and researchers in the field of high-speed vehicle design. Data can be displayed and printed in several formats. An information window displays a brief description of the material with properties at standard pressure and temperature. A spread sheet window displays complete, detailed property information. Properties which are a function of temperature and/or pressure can be displayed as graphs. In any display the data can be converted from English to SI units with the click of a button. Two material databases included with TPSX are: 1) materials used and/or developed by the Thermal Protection Branch at NASA Ames Research Center, and 2) a database compiled by NASA Johnson Space Center 9JSC). The Ames database contains over 60 advanced TPS materials including flexible blankets, rigid ceramic tiles, and ultra-high temperature ceramics. The JSC database contains over 130 insulative and structural materials. The Ames database is periodically updated and expanded as required to include newly developed materials and material property refinements.

  12. Vanadium oxide based materials: Synthesis, characterization and gas sensing properties

    NASA Astrophysics Data System (ADS)

    Ayesh, Samar I.

    In recent years, the demand for gas sensors based on safety and process control requirements has been expanding. The reason for such demand sterns from environmental and safety concerns since the toxic gases released from automobile exhausts and chemical plants can directly or indirectly pollute our environment and affect our health. Among the chemicals studied, nitrogen oxide (NOx) gases are among the most dangerous air pollutants. Transition metal oxide clusters (or polyoxometalates) provide an exciting opportunity for the design and synthesis of a new generation of materials for efficient NOx sensing. Polyoxometalates are an important and fast emerging class of compounds that exhibit many remarkable properties. Chapter 1 provides introduction and background of chemical sensors. It describes the need for gas sensors and the current status of research in the area of NOx gas sensors in particular. A description of polyoxmetalates and their relevance as potential novel gas sensor materials is also given. Chapter 2 describes the synthesis and characterization by FTIR spectroscopy, elemental analysis, thermogravimetric analysis, manganometric titration, bond valence sum calculation, temperature dependent magnetic properties studies, electron paramagnetic resonance, and complete single crystal X-ray diffraction analysis of newly prepared vanadium oxide based-systems that have been discovered during the course of this work. First, the system containing arrays of decavanadates networked by extensive hydrogen bonding with cyclic nitrogen bases are described. This is followed by the mixed-valence vanadium oxide cluster, [VV 13VIV3O42(Cl)]-7, containing a hitherto unknown vanadium oxide framework structure. Finally the synthesis of 3D-framework materials is described. These compounds have highly symmetrical closely related three-dimensional framework structures consisting vanadium oxide shells {V18O42(XO4)} linked via heterometallic atoms {M' = Cd, Zn} into three

  13. Process Formulations And Curing Conditions That Affect Saltstone Properties

    SciTech Connect

    Reigel, M. M.; Pickenheim, B. R.; Daniel, W. E.

    2012-09-28

    The first objective of this study was to analyze saltstone fresh properties to determine the feasibility of reducing the formulation water to premix (w/p) ratio while varying the amount of extra water and admixtures used during processing at the Saltstone Production Facility (SPF). The second part of this study was to provide information for understanding the impact of curing conditions (cure temperature, relative humidity (RH)) and processing formulation on the performance properties of cured saltstone.

  14. Processing Conditions Affecting Grain Size and Mechanical Properties in Nanocomposites Produced via Cold Spray

    NASA Astrophysics Data System (ADS)

    Cavaliere, P.; Perrone, A.; Silvello, A.

    2014-10-01

    Cold spray is a coating technology based on aerodynamics and high-speed impact dynamics. In this process, spray particles (usually 1-50 μm in diameter) are accelerated to a high velocity (typically 300-1200 m/s) by a high-speed gas (pre-heated air, nitrogen, or helium) flow that is generated through a convergent-divergent de Laval-type nozzle. A coating is formed through the intensive plastic deformation of particles impacting on a substrate at a temperature below the melting point of the spray material. In the present paper the main processing parameters affecting the microstructural and mechanical behavior of metal-metal cold spray deposits are described. The effect of process parameters on grain refinement and mechanical properties were analyzed for composite particles of Al-Al2O3, Ni-BN, Cu-Al2O3, and Co-SiC. The properties of the formed nanocomposites were compared with those of the parent materials sprayed under the same conditions. The process conditions, leading to a strong grain refinement with an acceptable level of the deposit mechanical properties such as porosity and adhesion strength, are discussed.

  15. Concepts and techniques for ultrasonic evaluation of material mechanical properties

    NASA Technical Reports Server (NTRS)

    Vary, A.

    1980-01-01

    The ultrasonic nondestructive evaluation techniques discussed in the present paper indicate potentials for material characterization and property prediction. Stress wave interaction and material transfer function concepts are examined as a basis for explaining correlations between material mechanical behavior and ultrasonically measured quantities. It is observed that the effect and criticality of any discrete flaw, such as crack, inclusion, or any other stress raiser, is definable only in terms of its material microstructural environment. This underscores the importance of ultrasonic techniques capable of characterizing the stress wave energy transfer properties of a material.

  16. 46 CFR 164.013-3 - Material properties and workmanship.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal Pattern) § 164.013-3 Material properties and workmanship. (a) General. The unicellular.... Unicellular polyethylene foam must comply with the requirements of UL 1191, sections 24, 25, and 26 and...

  17. 46 CFR 164.013-3 - Material properties and workmanship.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal Pattern) § 164.013-3 Material properties and workmanship. (a) General. The unicellular.... Unicellular polyethylene foam must comply with the requirements of UL 1191, sections 24, 25, and 26 and...

  18. 46 CFR 164.013-3 - Material properties and workmanship.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ..., AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal Pattern) § 164.013-3 Material properties and workmanship. (a) General. The unicellular.... Unicellular polyethylene foam must comply with the requirements of UL 1191, sections 24, 25, and 26 and...

  19. 46 CFR 164.013-3 - Material properties and workmanship.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal Pattern) § 164.013-3 Material properties and workmanship. (a) General. The unicellular.... Unicellular polyethylene foam must comply with the requirements of UL 1191, sections 24, 25, and 26 and...

  20. 46 CFR 164.013-3 - Material properties and workmanship.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ..., AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal Pattern) § 164.013-3 Material properties and workmanship. (a) General. The unicellular.... Unicellular polyethylene foam must comply with the requirements of UL 1191, sections 24, 25, and 26 and...

  1. A study of thermoelectric properties of graphene materials

    NASA Astrophysics Data System (ADS)

    Twombly, Chris

    Graphene has very beneficial charge transport properties which make it an interesting potential thermoelectric material, but its thermoelectric efficiency is limited by large thermal conductivity. Nanostructuring graphene by incorporating periodic holes in the crystal structure produces graphene nanomesh with reduced thermal conductivity due to increased phonon scattering. The goal of this study was to investigate the thermoelectric properties of graphene nanomeshes and defected graphene using Density Functional Theory and semi-classical Boltzmann Transport Theory. We computed the Seebeck coefficient, electrical conductivity, and the electrical component of thermal conductivity from first principles. We first developed and verified the accuracy of our techniques using silicon. We then examined the properties of silicon nanowires in order to study systems with more complex geometry and to show that nanostructuring can improve thermoelectric properties. Our results agreed closely with previous experimental and theoretical studies of silicon systems. We then employed this suite of methods to study graphene, graphene nanomeshes, and periodically defected graphene. Our calculations for pristine graphene agreed closely with experimental measurements, proving that our methods work well with 2D systems. Our calculations suggest that there is up to a one order of magnitude increase in Seebeck coefficient for graphene nanomeshes compared to pristine graphene. This increase was found to be strongly dependent on a previously predicted geometrically based semimetal to semiconductor transition. We estimated a maximum ZT of 0.15-0.4 for graphene nanomeshes based on a simple scaling law for the thermal conductivity in these systems. The ZT value is strongly dependent on the purity and the quality of the graphene crystal lattice, which affects the relaxation time of charge carriers in these systems. We then studied defected graphene with partial hydrogen passivation and boron

  2. Fish gelatin: Material properties and applications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The main difference between fish gelatin and mammalian gelatin is fish gelatin’s lower gelation temperature. This property limits the use of fish gelatin in applications that currently utilize mammalian gelatin. However, fish gelatin remains an attractive alterative to mammalian gelatin due to relig...

  3. Effects of tritium on material properties

    SciTech Connect

    Caskey, G.R. Jr.

    1985-01-01

    The effecs of tritium on deformation and fracture of metals are reviewed with emphasis on similarities and differences between tritium and the other hydrogen isotopes. Helium generated by radioactive decay of tritium introduces time dependent property changes not observed with protium or deuterium. On-going studies and topics for further investigations are identified. 17 refs., 6 figs., 9 tabs.

  4. Organic materials with nonlinear optical properties

    DOEpatents

    Stupp, S.I.; Son, S.; Lin, H.C.

    1995-05-02

    The present invention is directed to organic materials that have the ability to double or triple the frequency of light that is directed through the materials. Particularly, the present invention is directed to the compound 4-[4-(2R)-2-cyano-7-(4{prime}-pentyloxy-4-biphenylcarbonyloxy)phenylheptylidenephenylcarbonyloxy]benzaldehyde, which can double the frequency of light that is directed through the compound. The invention is also directed to the compound (12-hydroxy-5,7-dodecadiynyl)-4{prime}-[(4{prime}-pentyloxy-4-biphenyl)carbonyloxy]-4-biphenylcarboxylate, and its polymeric form. The polymeric form can triple the frequency of light directed through it. 4 figs.

  5. Quantitative measurement of nanomechanical properties in composite materials

    NASA Astrophysics Data System (ADS)

    Zhao, Wei

    In this work, quantitative Atomic force acoustic microscopy (AFAM) was used to measure nanomechanical properties and to determine microstructural morphology in fiber reinforced composites and hard calcified tissue. In carbon fiber reinforced composites, the fiber-matrix interphase is of interest as it affects the primary load-transfer process and thereby bulk mechanical properties of reinforced composites. The study of properties in the interphase region is important for an understanding of the bulk mechanical properties, which have been shown affected by moisture-based environmental degradation. Single point AFAM testing has been used to quantitatively determine elastic properties at the fiber-matrix interphase by taking advantage of the high spatial scanning resolution capable of measuring interphase dimensions. Carbon-fiber epoxy composite samples were degraded in laboratory conditions by exposure to a accelerated hydrothermal degradation environment in deionized water and salt water. Composite degradation has been characterized by the change in the epoxy matrix contact stiffness and the interphase properties. A decrease in matrix stiffness was found to coincide with the environmental exposure and moisture absorption of the samples. Interphase stiffness measurements indicate a constant interphase thickness as a function of environmental exposure. Chemical analysis of the epoxy using FTIR and Raman spectroscopy indicate hydrolysis of the C-O-C and Epoxide bonds which contribute to the decrease in epoxy mechanical properties. Accelerated degradation by salt water and deionized water both resulted in degradation of the epoxy, though the presence of sodium chloride showed less degradation. From SEM, debonding of the fiber-matrix interface was observed to be more severe when exposed to a salt water environment. In performing quantitative AFAM measurements, the effects of tip shape on the contact mechanics at the epoxy interface were found to influence the reported

  6. Tuning Surface Properties of Low Dimensional Materials via Strain Engineering.

    PubMed

    Yang, Shengchun; Liu, Fuzhu; Wu, Chao; Yang, Sen

    2016-08-01

    The promising and versatile applications of low dimensional materials are largely due to their surface properties, which along with their underlying electronic structures have been well studied. However, these materials may not be directly useful for applications requiring properties other than their natal ones. In recent years, strain has been shown to be an additionally useful handle to tune the physical and chemical properties of materials by changing their geometric and electronic structures. The strategies for producing strain are summarized. Then, the electronic structure of quasi-two dimensional layered non-metallic materials (e.g., graphene, MX2, BP, Ge nanosheets) under strain are discussed. Later, the strain effects on catalytic properties of metal-catalyst loaded with strain are focused on. Both experimental and computational perspectives for dealing with strained systems are covered. Finally, an outlook on engineering surface properties utilizing strain is provided. PMID:27376498

  7. Spray characteristics affected by physical properties of adjuvants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Four drift adjuvants, Array, In-Place, Vector and Control, were tested and physical properties and spray spectrum parameters measured. Array had the highest conductivity, indicating a good potential for the electrostatic charging, and the highest shear viscosity. All adjuvants had very similar neut...

  8. IMAP: Interferometry for Material Property Measurement in MEMS

    SciTech Connect

    Jensen, B.D.; Miller, S.L.; de Boer, M.P.

    1999-03-10

    An interferometric technique has been developed for non-destructive, high-confidence, in-situ determination of material properties in MEMS. By using interferometry to measure the full deflection curves of beams pulled toward the substrate under electrostatic loads, the actual behavior of the beams has been modeled. No other method for determining material properties allows such detailed knowledge of device behavior to be gathered. Values for material properties and non-idealities (such as support post compliance) have then been extracted which minimize the error between the measured and modeled deflections. High accuracy and resolution have been demonstrated, allowing the measurements to be used to enhance process control.

  9. Data base for crack growth properties of materials

    NASA Technical Reports Server (NTRS)

    Forman, Royce G.; Lawrence, Victor B.; Nguy, Henry L.

    1988-01-01

    A computerized data base of crack growth properties of materials was developed for use in fracture control analysis of rocket engine components and other NASA space hardware. The software system has files of basic crack growth rate data, other fracture mechanics material properties such as fracture toughness and environmental crack growth threshold values, and plotting and fitting routines for deriving material properties for use in fracture control analysis. An extensive amount of data was collected and entered, and work is continuing on compiling additional data. The data base and software codes are useful both for fracture control analysis and for evaluation or development of improved crack growth theories.

  10. Soil properties affecting wheat yields following drilling-fluid application.

    PubMed

    Bauder, T A; Barbarick, K A; Ippolito, J A; Shanahan, J F; Ayers, P D

    2005-01-01

    Oil and gas drilling operations use drilling fluids (mud) to lubricate the drill bit and stem, transport formation cuttings to the surface, and seal off porous geologic formations. Following completion of the well, waste drilling fluid is often applied to cropland. We studied potential changes in soil compaction as indicated by cone penetration resistance, pH, electrical conductivity (EC(e)), sodium adsorption ratio (SAR), extractable soil and total straw and grain trace metal and nutrient concentrations, and winter wheat (Triticum aestivum L. 'TAM 107') grain yield following water-based, bentonitic drilling-fluid application (0-94 Mg ha(-1)) to field test plots. Three methods of application (normal, splash-plate, and spreader-bar) were used to study compaction effects. We measured increasing SAR, EC(e), and pH with drilling-fluid rates, but not to levels detrimental to crop production. Field measurements revealed significantly higher compaction within areas affected by truck travel, but also not enough to affect crop yield. In three of four site years, neither drilling-fluid rate nor application method affected grain yield. Extractions representing plant availability and plant analyses results indicated that drilling fluid did not significantly increase most trace elements or nutrient concentrations. These results support land application of water-based bentonitic drilling fluids as an acceptable practice on well-drained soils using controlled rates. PMID:16091622

  11. Properties of materials using acoustic waves

    NASA Astrophysics Data System (ADS)

    Apfel, R. E.

    1985-10-01

    Our goal of characterizing materials using acoustic waves was forwarded through a number of projects: (1) We have derived a theory, and tested it on tissues, for predicting the composition of composite materials using mixture rules, such as the one we derived for the nonlinear parameter two years ago; (2) We have published one article and another is in review on our use of modulated acoustic radiation pressure on levitated drops to characterize interfaces with and without surfactants. We have begun to study in a systematic way the nonlinear dynamics of drops, including drop fission: (3) we have improved apparatus for 30 MHz ultrasonic scattering from microparticles (approx. micron size), which should allow us to discriminate between different microparticles in a liquid; (4) We have begun to study the nonlinear mechanics of hydrodynamic solitons in cylindrical (2-d) geometry; and (5) We have been studying the use of acoustic levitation for transducer calibration.

  12. Properties of cathode materials in alkaline cells

    NASA Astrophysics Data System (ADS)

    Salkind, A. J.; McBreen, J.; Freeman, R.; Parkhurst, W. A.

    1984-04-01

    Conventional and new cathode materials in primary and secondary alkaline cells were investigated for stability, structure, electrochemical reversibility and efficiency. Included were various forms of AgO for reserve type silver zinc batteries, a new material - AgNiO2 and several nickel electrodes for nickel cadmium and nickel hydrogen cells for aerospace applications. A comparative study was made of the stability of electroformed and chemically prepared AgO. Stability was correlated with impurities. After the first discharge AgNiO2 can be recharged to the monovalent level. The discharge product is predominantly silver. Plastic bonded nickel electrodes display a second plateau on discharge. Additions of Co(OH)2 largely eliminate this.

  13. Mapping the fracture properties of engineering materials

    NASA Astrophysics Data System (ADS)

    Ashby, Mike

    2013-09-01

    Among Alan Cottrell's many extraordinary talents was that of an inspirational teacher. He had a masterful ability to explain the underlying physics of the Science of Materials and at the same time to simplify and to present the big picture. His teaching-texts live on, still among the clearest and most insightful expositions of the subject. This paper surveys part of one of the fields to which he contributed so much - Fracture - with education and the big picture in mind.

  14. Temperature dependent terahertz properties of energetic materials

    NASA Astrophysics Data System (ADS)

    Azad, Abul K.; Whitley, Von H.; Brown, Kathryn E.; Ahmed, Towfiq; Sorensen, Christian J.; Moore, David S.

    2016-04-01

    Reliable detection of energetic materials is still a formidable challenge which requires further investigation. The remote standoff detection of explosives using molecular fingerprints in the terahertz spectral range has been an evolving research area for the past two decades. Despite many efforts, identification of a particular explosive remains difficult as the spectral fingerprints often shift due to the working conditions of the sample such as temperature, crystal orientation, presence of binders, etc. In this work, we investigate the vibrational spectrum of energetic materials including RDX, PETN, AN, and 1,3-DNB diluted in a low loss PTFE host medium using terahertz time domain spectroscopy (THz-TDS) at cryogenic temperatures. The measured absorptions of these materials show spectral shifts of their characteristic peaks while changing their operating temperature from 300 to 7.5 K. We have developed a theoretical model based on first principles methods, which is able to predict most of the measured modes in 1, 3-DNB between 0.3 to 2.50 THz. These findings may further improve the security screening of explosives.

  15. Optical techniques for determining dynamic material properties

    SciTech Connect

    Paisley, D.L.; Stahl, D.B.

    1996-12-31

    Miniature plates are laser-launched with a 10-Joule Nd:YAG for one-dimensional (1-D) impacts on to target materials much like gas gun experiments and explosive plane wave plate launch. By making the experiments small, flyer plates (3 mm diameter x 50 micron thick) and targets (10 mm diameter x 200 micron thick), 1-D impact experiments can be performed in a standard laser-optical laboratory with minimum confinement and collateral damage. The laser-launched plates do not require the traditional sabot on gas guns nor the explosives needed for explosive planewave lenses, and as a result are much more amenable to a wide variety of materials and applications. Because of the small size very high pressure gradients can be generated with relative ease. The high pressure gradients result in very high strains and strain rates that are not easily generated by other experimental methods. The small size and short shock duration (1 - 20 ns) are ideal for dynamically measuring bond strengths of micron-thick coatings. Experimental techniques, equipment, and dynamic material results are reported.

  16. Materials properties: heterogeneity and appropriate sampling modes.

    PubMed

    Esbensen, Kim H

    2015-01-01

    The target audience for this Special Section comprises parties related to the food and feed sectors, e.g., field samplers, academic and industrial scientists, laboratory personnel, companies, organizations, regulatory bodies, and agencies who are responsible for sampling, as well as project leaders, project managers, quality managers, supervisors, and directors. All these entities face heterogeneous materials, and the characteristics of heterogeneous materials needs to be competently understood by all of them. Before delivering analytical results for decision-making, one form or other of primary sampling is always necessary, which must counteract the effects of the sampling target heterogeneity. Up to five types of sampling error may arise as a specific sampling process interacts with a heterogeneous material; two sampling errors arise because of the heterogeneity of the sampling target, and three additional sampling errors are produced by the sampling process itself-if not properly understood, reduced, and/or eliminated, which is the role of Theory of Sampling. This paper discusses the phenomenon and concepts involved in understanding, describing, and managing the adverse effects of heterogeneity in sampling. PMID:25807041

  17. Biochar physico-chemical properties as affected by environmental exposure.

    PubMed

    Sorrenti, Giovambattista; Masiello, Caroline A; Dugan, Brandon; Toselli, Moreno

    2016-09-01

    To best use biochar as a sustainable soil management and carbon (C) sequestration technique, we must understand the effect of environmental exposure on its physical and chemical properties because they likely vary with time. These properties play an important role in biochar's environmental behavior and delivery of ecosystem services. We measured biochar before amendment and four years after amendment to a commercial nectarine orchard at rates of 5, 15 and 30tha(-1). We combined two pycnometry techniques to measure skeletal (ρs) and envelope (ρe) density and to estimate the total pore volume of biochar particles. We also examined imbibition, which can provide information about soil hydraulic conductivity. Finally, we investigated the chemical properties, surface, inner layers atomic composition and C1s bonding state of biochar fragments through X-ray photoelectron spectroscopy (XPS). Ageing increased biochar skeletal density and reduced the water imbibition rate within fragments as a consequence of partial pore clogging. However, porosity and the volume of water stored in particles remained unchanged. Exposure reduced biochar pH, EC, and total C, but enhanced total N, nitrate-N, and ammonium-N. X-ray photoelectron spectroscopy analyses showed an increase of O, Si, N, Na, Al, Ca, Mn, and Fe surface (0-5nm) atomic composition (at%) and a reduction of C and K in aged particles, confirming the interactions of biochar with soil inorganic and organic phases. Oxidation of aged biochar fragments occurred mainly in the particle surface, and progressively decreased down to 75nm. Biochar surface chemistry changes included the development of carbonyl and carboxylate functional groups, again mainly on the particle surface. However, changes were noticeable down to 75nm, while no significant changes were measured in the deepest layer, up to 110nm. Results show unequivocal shifts in biochar physical and chemical properties/characteristics over short (~years) timescales. PMID

  18. The Affect and Arousal Scales: Psychometric Properties of the Dutch Version and Multigroup Confirmatory Factor Analyses

    ERIC Educational Resources Information Center

    De Bolle, Marleen; De Fruyt, Filip; Decuyper, Mieke

    2010-01-01

    Psychometric properties of the Dutch version of the Affect and Arousal Scales (AFARS) were inspected in a combined clinical and population sample (N = 1,215). The validity of the tripartite structure and the relations between Negative Affect, Positive Affect, and Physiological Hyperarousal (PH) were investigated for boys and girls, younger (8-11…

  19. Interdisciplinary research concerning the nature and properties of ceramic materials

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The nature and properties of ceramic materials as they relate to solid state physics and metallurgy are studied. Special attention was given to the applications of ceramics to NASA programs and national needs.

  20. Carboxymethyl modification of konjac glucomannan affects water binding properties.

    PubMed

    Xiao, Man; Dai, Shuhong; Wang, Le; Ni, Xuewen; Yan, Wenli; Fang, Yapeng; Corke, Harold; Jiang, Fatang

    2015-10-01

    The water binding properties of konjac glucomannan (KGM) and carboxymethyl konjac glucomannan (CMKGM) are important for their application in food, pharmaceutical, and chemical engineering fields. The equilibrium moisture content of CMKGM was lower than that of KGM at the relative humidity in the range 30-95% at 25°C. The water absorption and solubility of CMKGM in water solution were lower than that of KGM at 25°C. Carboxymethyl modification of KGM reduces the water adsorption, absorption, and solubility. Both carboxymethylation and deacetylation could confer hydrophobicity for CMKGM. These data provide the basis for expanding CMKGM application. PMID:26076594

  1. Material properties of concentrated pectin networks.

    PubMed

    Zsivanovits, Gabor; MacDougall, Alistair J; Smith, Andrew C; Ring, Stephen G

    2004-05-17

    We have examined the mechanical behaviour of different types of pectin at high concentrations (> 30% w/w), relevant to the behaviour of pectin in the plant cell wall, and as a film-forming agent. Mechanical properties were examined as a function of counterion type (K(+), Ca(2+), Mg(2+)), concentration and extent of hydration. Hydration was controlled in an osmotic stress experiment where pectin films were exposed to concentrated polyethylene glycol [PEG] solutions of known osmotic pressure. We investigated the mechanical behaviour under simple extension. The results show that the swelling and stiffness of the films are strongly dependent on pectin source and ionic environment. At a fixed osmotic stress, both Ca(2+) or Mg(2+) counterions reduce swelling and increase the stiffness of the film. PMID:15113669

  2. Some functional properties of composite material based on scrap tires

    NASA Astrophysics Data System (ADS)

    Plesuma, Renate; Malers, Laimonis

    2013-09-01

    The utilization of scrap tires still obtains a remarkable importance from the aspect of unloading the environment from non-degradable waste [1]. One of the most prospective ways for scrap tires reuse is a production of composite materials [2] This research must be considered as a continuation of previous investigations [3, 4]. It is devoted to the clarification of some functional properties, which are considered important for the view of practical applications, of the composite material. Some functional properties of the material were investigated, for instance, the compressive stress at different extent of deformation of sample (till 67% of initial thickness) (LVS EN 826) [5] and the resistance to UV radiation (modified method based on LVS EN 14836) [6]. Experiments were realized on the purposefully selected samples. The results were evaluated in the correlation with potential changes of Shore C hardness (Shore scale, ISO 7619-1, ISO 868) [7, 8]. The results showed noticeable resistance of the composite material against the mechanical influence and ultraviolet (UV) radiation. The correlation with the composition of the material, activity of binder, definite technological parameters, and the conditions supported during the production, were determined. It was estimated that selected properties and characteristics of the material are strongly dependent from the composition and technological parameters used in production of the composite material, and from the size of rubber crumb. Obtained results show possibility to attain desirable changes in the composite material properties by changing both the composition and technological parameters of examined material.

  3. Novel thermal properties of nanostructured materials.

    SciTech Connect

    Eastman, J. A.

    1999-01-13

    A new class of heat transfer fluids, termed nanofluids, has been developed by suspending nanocrystalline particles in liquids. Due to the orders-of-magnitude larger thermal conductivities of solids compared to those of liquids such as water, significantly enhanced thermal properties are obtained with nanofluids. For example, an approximately 20% improvement in effective thermal conductivity is observed when 5 vol.% CuO nanoparticles are added to water. Even more importantly, the heat transfer coefficient of water under dynamic flow conditions is increased more than 15% with the addition of less than 1 vol.% CuO particles. The use of nanofluids could impact many industrial sectors, including transportation, energy supply and production, electronics, textiles, and paper production by, for example, decreasing pumping power needs or reducing heat exchanger sizes. In contrast to the enhancement in effective thermal transport rates that is obtained when nanoparticles are suspended in fluids, nanocrystalline coatings are expected to exhibit reduced thermal conductivities compared to coarse-grained coatings. Reduced thermal conductivities are predicted to arise because of a reduction in the mean free path of phonons due to presence of grain boundaries. This behavior, combined with improved mechanical properties, makes nanostructured zirconia coatings excellent candidates for future applications as thermal barriers. Yttria-stabilized zirconia (YSZ) thin films are being produced by metal-organic chemical vapor deposition techniques. Preliminary results have indicated that the thermal conductivity is reduced by approximately a factor-of-two at room temperature in 10 nm grain-sized YSZ compared to coarse-grained or single crystal YSZ.

  4. Electrical properties of commercial sheet insulation materials for cryogenic applications

    SciTech Connect

    Tuncer, Enis; Sauers, Isidor; James, David Randy; Ellis, Alvin R; Pace, Marshall O

    2008-01-01

    Dielectric properties of electrical insulation materials are needed for low-temperature power applications. Performance of materials and their compatibility determine the size of the electrical insulation in power equipment. In this work we report the dielectric properties of some commercially available materials in sheet form. The selected materials are polypropylene laminated paper from Sumitomo Electric U.S.A., Inc., porous polyethylene (Tyvek\\texttrademark) from Dupont, and polyamide paper (Nomex\\texttrademark) from Dupont. The dielectric properties are characterized with an electrical impedance analyzer in the frequency domain. The impedances are recorded in a cryocooler in the temperature range from 50 to 300 K. The dielectric breakdown characteristics of the materials are measured in a liquid nitrogen bath at atmospheric pressure.

  5. Thermal Properties of Structural Materials Used in LWR Vessels

    SciTech Connect

    J. E. Daw; J. L. Rempe; D. L. Knudson

    2011-01-01

    High temperature material property data for structural materials used in existing Light Water Reactors (LWRs) are limited. Often, extrapolated values recommended in the literature differ significantly. To reduce uncertainties in predictions relying upon extrapolated data for LWR vessel and penetration materials, high temperature tests were completed on SA533 Grade B, Class 1 (SA533B1) low alloy steel, Stainless Steel 304 (SS304), and Inconel 600 using material property measurement systems available in the High Temperature Test Laboratory (HTTL) at the Idaho National Laboratory (INL). Properties measured include thermal expansion, specific heat capacity, and thermal diffusivity for temperatures up to 1200 °C. From these results, thermal conductivity and density were calculated. Results show that, in some cases, previously recommended values for these materials differ significantly from measured values at high temperatures.

  6. Does severity of dermatochalasis in aging affect corneal biomechanical properties?

    PubMed Central

    Atalay, Kurşat; Gurez, Ceren; Kirgiz, Ahmet; Serefoglu Cabuk, Kubra

    2016-01-01

    Purpose The aim of this study was to investigate the possibility of a relationship between corneal biomechanical properties and different grades of dermatochalasis. Patients and methods Patients were assigned to four groups according to the severity of their dermatochalasis: normal (Group 1), mild (Group 2), moderate (Group 3), and severe (Group 4). An Ocular Response Analyzer device was used to measure corneal hysteresis (CH), corneal resistance factor (CRF), and corneal-compensated intraocular pressure (IOPcc). Results We found no significant differences in the mean values of the CH, CRF, and IOPcc of all groups (P=0.75, P=0.93, and P=0.11, respectively). However, CH and IOPcc were negatively correlated in Group 1, Group 2, and Group 3 patients (P=0.013, r=−0.49; P=0.015, r=−0.52; and P=0.011, r=−0.47, respectively), but this correlation was not apparent in the Group 4 patients (P=0.57, r=0.12). CRF and IOPcc were correlated, but only in Group 4 (P=0.001, r=0.66). Conclusion Severe dermatochalasis was associated with altered corneal biomechanical properties. Some of the important visual consequences of dermatochalasis and related diseases (such as floppy eyelid syndrome) can be understood by considering corneal biomechanical alterations. PMID:27274214

  7. Determining significant material properties: A discovery approach

    NASA Technical Reports Server (NTRS)

    Karplus, Alan K.

    1992-01-01

    The following is a laboratory experiment designed to further understanding of materials science. The experiment itself can be informative for persons of any age past elementary school, and even for some in elementary school. The preparation of the plastic samples is readily accomplished by persons with resonable dexterity in the cutting of paper designs. The completion of the statistical Design of Experiments, which uses Yates' Method, requires basic math (addition and subtraction). Interpretive work requires plotting of data and making observations. Knowledge of statistical methods would be helpful. The purpose of this experiment is to acquaint students with the seven classes of recyclable plastics, and provide hands-on learning about the response of these plastics to mechanical tensile loading.

  8. Analytic Thermoelectric Couple Modeling: Variable Material Properties and Transient Operation

    NASA Technical Reports Server (NTRS)

    Mackey, Jonathan A.; Sehirlioglu, Alp; Dynys, Fred

    2015-01-01

    To gain a deeper understanding of the operation of a thermoelectric couple a set of analytic solutions have been derived for a variable material property couple and a transient couple. Using an analytic approach, as opposed to commonly used numerical techniques, results in a set of useful design guidelines. These guidelines can serve as useful starting conditions for further numerical studies, or can serve as design rules for lab built couples. The analytic modeling considers two cases and accounts for 1) material properties which vary with temperature and 2) transient operation of a couple. The variable material property case was handled by means of an asymptotic expansion, which allows for insight into the influence of temperature dependence on different material properties. The variable property work demonstrated the important fact that materials with identical average Figure of Merits can lead to different conversion efficiencies due to temperature dependence of the properties. The transient couple was investigated through a Greens function approach; several transient boundary conditions were investigated. The transient work introduces several new design considerations which are not captured by the classic steady state analysis. The work helps to assist in designing couples for optimal performance, and also helps assist in material selection.

  9. Chemical hydrogen storage material property guidelines for automotive applications

    NASA Astrophysics Data System (ADS)

    Semelsberger, Troy A.; Brooks, Kriston P.

    2015-04-01

    Chemical hydrogen storage is the sought after hydrogen storage media for automotive applications because of the expected low pressure operation (<20 atm), moderate temperature operation (<200 °C), system gravimetric capacities (>0.05 kg H2/kgsystem), and system volumetric capacities (>0.05 kg H2/Lsystem). Currently, the primary shortcomings of chemical hydrogen storage are regeneration efficiency, fuel cost and fuel phase (i.e., solid or slurry phase). Understanding the required material properties to meet the DOE Technical Targets for Onboard Hydrogen Storage Systems is a critical knowledge gap in the hydrogen storage research community. This study presents a set of fluid-phase chemical hydrogen storage material property guidelines for automotive applications meeting the 2017 DOE technical targets. Viable material properties were determined using a boiler-plate automotive system design. The fluid-phase chemical hydrogen storage media considered in this study were neat liquids, solutions, and non-settling homogeneous slurries. Material properties examined include kinetics, heats of reaction, fuel-cell impurities, gravimetric and volumetric hydrogen storage capacities, and regeneration efficiency. The material properties, although not exhaustive, are an essential first step in identifying viable chemical hydrogen storage material properties-and most important, their implications on system mass, system volume and system performance.

  10. MIDAS (Material Implementation, Database, and Analysis Source): A comprehensive resource of material properties

    SciTech Connect

    Tang, M; Norquist, P; Barton, N; Durrenberger, K; Florando, J; Attia, A

    2010-12-13

    MIDAS is aimed to be an easy-to-use and comprehensive common source for material properties including both experimental data and models and their parameters. At LLNL, we will develop MIDAS to be the central repository for material strength related data and models with the long-term goal to encompass other material properties. MIDAS will allow the users to upload experimental data and updated models, to view and read materials data and references, to manipulate models and their parameters, and to serve as the central location for the application codes to access the continuously growing model source codes. MIDAS contains a suite of interoperable tools and utilizes components already existing at LLNL: MSD (material strength database), MatProp (database of materials properties files), and MSlib (library of material model source codes). MIDAS requires significant development of the computer science framework for the interfaces between different components. We present the current status of MIDAS and its future development in this paper.

  11. 12 CFR 617.7630 - Does this Federal requirement affect any state property laws?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... property laws? 617.7630 Section 617.7630 Banks and Banking FARM CREDIT ADMINISTRATION FARM CREDIT SYSTEM BORROWER RIGHTS Right of First Refusal § 617.7630 Does this Federal requirement affect any state property... first refusal under the law of the state in which the property is located....

  12. 12 CFR 617.7630 - Does this Federal requirement affect any state property laws?

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... property laws? 617.7630 Section 617.7630 Banks and Banking FARM CREDIT ADMINISTRATION FARM CREDIT SYSTEM BORROWER RIGHTS Right of First Refusal § 617.7630 Does this Federal requirement affect any state property... first refusal under the law of the state in which the property is located....

  13. 12 CFR 617.7630 - Does this Federal requirement affect any state property laws?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... property laws? 617.7630 Section 617.7630 Banks and Banking FARM CREDIT ADMINISTRATION FARM CREDIT SYSTEM BORROWER RIGHTS Right of First Refusal § 617.7630 Does this Federal requirement affect any state property... first refusal under the law of the state in which the property is located....

  14. 12 CFR 617.7630 - Does this Federal requirement affect any state property laws?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... property laws? 617.7630 Section 617.7630 Banks and Banking FARM CREDIT ADMINISTRATION FARM CREDIT SYSTEM BORROWER RIGHTS Right of First Refusal § 617.7630 Does this Federal requirement affect any state property... first refusal under the law of the state in which the property is located....

  15. 12 CFR 617.7630 - Does this Federal requirement affect any state property laws?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... property laws? 617.7630 Section 617.7630 Banks and Banking FARM CREDIT ADMINISTRATION FARM CREDIT SYSTEM BORROWER RIGHTS Right of First Refusal § 617.7630 Does this Federal requirement affect any state property... first refusal under the law of the state in which the property is located....

  16. Rheological properties of ovalbumin hydrogels as affected by surfactants addition.

    PubMed

    Hassan, Natalia; Messina, Paula V; Dodero, Veronica I; Ruso, Juan M

    2011-04-01

    The gel properties of ovalbumin mixtures with three different surfactants (sodium perfluorooctanoate, sodium octanoate and sodium dodecanoate) have been studied by rheological techniques. The gel elasticities were determined as a function of surfactant concentration and surfactant type. The fractal dimension of the formed structures was evaluated from plots of storage modulus against surfactant concentration. The role of electrostatic, hydrophobic and disulfide SS interactions in these systems has been demonstrated to be the predominant. The viscosity of these structures tends to increase with surfactant concentration, except for the fluorinated one. Unfolded ovalbumin molecules tend to form fibrillar structures that tend to increase with surfactant concentration, except for the fluorinated one. This fact has been related to the particular nature of this molecule. PMID:21262258

  17. Protein composition affects variation in coagulation properties of buffalo milk.

    PubMed

    Bonfatti, V; Gervaso, M; Rostellato, R; Coletta, A; Carnier, P

    2013-07-01

    The aim of this study was to investigate the effects exerted by the content of casein and whey protein fractions on variation of pH, rennet-coagulation time (RCT), curd-firming time (K20), and curd firmness of Mediterranean buffalo individual milk. Measures of milk protein composition and assessment of genotypes at CSN1S1 and CSN3 were obtained by reversed-phase HPLC analysis of 621 individual milk samples. Increased content of αS1-casein (CN) was associated with delayed coagulation onset and increased K20, whereas average pH, RCT, and K20 decreased when β-CN content increased. Milk with low κ-CN content exhibited low pH and RCT relative to milk with high content of κ-CN. Increased content of glycosylated κ-CN was associated with unfavorable effects on RCT. Effects of milk protein composition on curd firmness were less important than those on pH, RCT, and K20. Likely, this occurred as a consequence of the very short RCT of buffalo milk, which guaranteed a complete strengthening of the curd even in the restricted 31 min time of analysis of coagulation properties and for samples initially showing soft curds. Effects of CSN1S1-CSN3 genotypes on coagulation properties were not to be entirely ascribed to existing variation in milk protein composition associated with polymorphisms at CSN1S1 and CSN3 genes. Although the role of detailed milk protein composition in variation of cheese yield needs to be further investigated, findings of this study suggest that modification of the relative content of specific CN fractions can relevantly influence the behavior of buffalo milk during processing. PMID:23684020

  18. How SN Ia host-galaxy properties affect cosmological parameters

    NASA Astrophysics Data System (ADS)

    Campbell, H.; Fraser, M.; Gilmore, G.

    2016-04-01

    We present a systematic study of the relationship between Type Ia Supernova (SN Ia) properties, and the characteristics of their host galaxies, using a sample of 581 SNe Ia from the full Sloan Digital Sky Survey II (SDSS-II) SN Survey. We also investigate the effects of this on the cosmological constraints derived from SNe Ia. Compared to previous studies, our sample is larger by a factor of >4, and covers a substantially larger redshift range (up to z ˜ 0.5), which is directly applicable to the volume of cosmological interest. We measure a significant correlation (>5σ) between the host-galaxy stellar-mass and the SN Ia Hubble Residuals (HR). We find a weak correlation (1.4σ) between the host-galaxy metallicity as measured from emission lines in the spectra, and the SN Ia HR. We also find evidence that the slope of the correlation between host-galaxy mass and HR is -0.11 mag/log(Mhost/M⊙) steeper in lower metallicity galaxies. We test the effects on a cosmological analysis using both the derived best-fitting correlations between host parameters and HR, and by allowing an additional free parameter in the fit to account for host properties which we then marginalize over when determining cosmological parameters. We see a shift towards more negative values of the equation-of-state parameter w, along with a shift to lower values of Ωm after applying mass or metallicity corrections. The shift in cosmological parameters with host-galaxy stellar-mass correction is consistent with previous studies. We find a best-fitting cosmology of Ω m =0.266_{-0.016}^{+0.016}, Ω _{Λ }=0.740_{-0.018}^{+0.018} and w=-1.151_{-0.121}^{+0.123} (statistical errors only).

  19. Use of material dielectric properties for agricultural applications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of dielectric properties of materials for applications in agriculture are reviewed, and research findings on use of dielectric heating of materials and on sensing of product moisture content and other quality factors are discussed. Dielectric heating applications, include treatment of seed...

  20. Heat Transmission Properties of Insulating and Building Materials

    National Institute of Standards and Technology Data Gateway

    SRD 81 NIST Heat Transmission Properties of Insulating and Building Materials (Web, free access)   NIST has accumulated a valuable and comprehensive collection of thermal conductivity data. Version 1.0 of the database includes data for over 2000 measurements, covering several categories of materials including concrete, fiberboard, plastics, thermal insulation, and rubber.

  1. Material Properties for Fiber-Reinforced Silica Aerogels

    NASA Technical Reports Server (NTRS)

    White, Susan; Rouanet, Stephane; Moses, John; Arnold, James O. (Technical Monitor)

    1994-01-01

    Ceramic fiber-reinforced silica aerogels are novel materials for high performance insulation, including thermal protection materials. Experimental data are presented for the thermal and mechanical properties, showing the trends exhibited over a range of fiber loadings and silica aerogel densities. Test results are compared to that of unreinforced bulk aerogels.

  2. The design and modeling of periodic materials with novel properties

    NASA Astrophysics Data System (ADS)

    Berger, Jonathan Bernard

    Cellular materials are ubiquitous in our world being found in natural and engineered systems as structural materials, sound and energy absorbers, heat insulators and more. Stochastic foams made of polymers, metals and even ceramics find wide use due to their novel properties when compared to monolithic materials. Properties of these so called hybrid materials, those that combine materials or materials and space, are derived from the localization of thermomechanical stresses and strains on the mesoscale as a function of cell topology. The effects of localization can only be generalized in stochastic materials arising from their inherent potential complexity, possessing variations in local chemistry, microstructural inhomogeneity and topological variations. Ordered cellular materials on the other hand, such as lattices and honeycombs, make for much easier study, often requiring analysis of only a single unit-cell. Theoretical bounds predict that hybrid materials have the potential to push design envelopes offering lighter stiffer and stronger materials. Hybrid materials can achieve very low and even negative coefficients of thermal expansion (CTE) while retaining a relatively high stiffness -- properties completely unmatched by monolithic materials. In the first chapter of this thesis a two-dimensional lattice is detailed that possess near maximum stiffness, relative to the tightest theoretical bound, and low, zero and even appreciably negative thermal expansion. Its CTE and stiffness are given in closed form as a function of geometric parameters and the material properties. This result is confirmed with finite elements (FE) and experiment. In the second chapter the compressive stiffness of three-dimensional ordered foams, both closed and open cell, are predicted with FE and the results placed in property space in terms of stiffness and density. A novel structure is identified that effectively achieves theoretical bounds for Young's, shear and bulk modulus

  3. Perspective: Interactive material property databases through aggregation of literature data

    NASA Astrophysics Data System (ADS)

    Seshadri, Ram; Sparks, Taylor D.

    2016-05-01

    Searchable, interactive, databases of material properties, particularly those relating to functional materials (magnetics, thermoelectrics, photovoltaics, etc.) are curiously missing from discussions of machine-learning and other data-driven methods for advancing new materials discovery. Here we discuss the manual aggregation of experimental data from the published literature for the creation of interactive databases that allow the original experimental data as well additional metadata to be visualized in an interactive manner. The databases described involve materials for thermoelectric energy conversion, and for the electrodes of Li-ion batteries. The data can be subject to machine-learning, accelerating the discovery of new materials.

  4. Physicochemical properties of foal meat as affected by cooking methods.

    PubMed

    Lorenzo, José M; Cittadini, Aurora; Munekata, Paulo E; Domínguez, Rubén

    2015-10-01

    The present study deals with the effect of four different cooking techniques (roasting, grilling, microwave baking and frying with olive oil) on physicochemical parameters (cooking loss, WHC, texture and colour) and lipid oxidation (by TBARS measurement) of foal meat. Thermal treatments induced water loss (P<0.001), being lower in foal steaks cooked in the grill (25.8%) and higher in foal samples cooked in the microwave (39.5%). As it was expected, all the cooking methods increased TBARS index, since high temperature during cooking seems to cause an increase of the lipid oxidation in foal steaks. Statistical analysis displayed that WHC was affected (P<0.001) by thermal treatment, since the smallest WHC values were observed in samples from microwave treatment. Thermal treatment also caused a significant (P<0.001) increase in the force needed to cut the foal steaks. Regarding colour parameter, cooking led to an increase of L*-value (lightness) and b*-value (yellowness), while a*-value (redness) markedly decreased in all samples. PMID:26042921

  5. Alternative materials for solid oxide fuel cells: Factors affecting air-sintering of chromite interconnections

    SciTech Connect

    Chick, L.A.; Bates, J.L.

    1992-07-01

    The purpose of this research is to develop alternative materials for solid oxide fuel cell (SOFC) interconnections and electrodes with improved electrical, thermal and electrochemical properties. Another objective is to develop synthesis and fabrication processes for these materials whereby they can be consolidated in air into SOFCs. The approach is to (1) develop modifications of the current, state-of-the-art materials used in SOFCs, (2) minimize the number of cations used in the SOFC materials to reduce potential deleterious interactions, (3) improve thermal, electrical, and electrochemical properties, (4) develop methods to synthesize both state-of-the-art and alternative materials for the simultaneous fabrication and consolidation in air of the interconnections and electrodes with the solid electrolyte, and (5) understand electrochemical reactions at materials interfaces and the effects of component compositions and processing on those reactions.

  6. Compact rock material gas permeability properties

    NASA Astrophysics Data System (ADS)

    Wang, Huanling; Xu, Weiya; Zuo, Jing

    2014-09-01

    Natural compact rocks, such as sandstone, granite, and rock salt, are the main materials and geological environment for storing underground oil, gas, CO2, shale gas, and radioactive waste because they have extremely low permeabilities and high mechanical strengths. Using the inert gas argon as the fluid medium, the stress-dependent permeability and porosity of monzonitic granite and granite gneiss from an underground oil storage depot were measured using a permeability and porosity measurement system. Based on the test results, models for describing the relationships among the permeability, porosity, and confining pressure of rock specimens were analyzed and are discussed. A power law is suggested to describe the relationship between the stress-dependent porosity and permeability; for the monzonitic granite and granite gneiss (for monzonitic granite (A-2), the initial porosity is approximately 4.05%, and the permeability is approximately 10-19 m2; for the granite gneiss (B-2), the initial porosity is approximately 7.09%, the permeability is approximately 10-17 m2; and the porosity-sensitivity exponents that link porosity and permeability are 0.98 and 3.11, respectively). Compared with moderate-porosity and high-porosity rocks, for which φ > 15%, low-porosity rock permeability has a relatively lower sensitivity to stress, but the porosity is more sensitive to stress, and different types of rocks show similar trends. From the test results, it can be inferred that the test rock specimens' permeability evolution is related to the relative particle movements and microcrack closure.

  7. Thermophysical Properties of Polymer Materials with High Thermal Conductivity

    NASA Astrophysics Data System (ADS)

    Lebedev, S. M.; Gefle, O. S.; Dneprovskii, S. N.; Amitov, E. T.

    2015-06-01

    Results of studies on the main thermophysical properties of new thermally conductive polymer materials are presented. It is shown that modification of polymer dielectrics by micron-sized fillers allows thermally conductive materials with thermal conductivity not less than 2 W/(m K) to be produced, which makes it possible to use such materials as cooling elements of various electrical engineering and semiconductor equipment and devices.

  8. How Tissue Mechanical Properties Affect Enteric Neural Crest Cell Migration

    PubMed Central

    Chevalier, N.R.; Gazguez, E.; Bidault, L.; Guilbert, T.; Vias, C.; Vian, E.; Watanabe, Y.; Muller, L.; Germain, S.; Bondurand, N.; Dufour, S.; Fleury, V.

    2016-01-01

    Neural crest cells (NCCs) are a population of multipotent cells that migrate extensively during vertebrate development. Alterations to neural crest ontogenesis cause several diseases, including cancers and congenital defects, such as Hirschprung disease, which results from incomplete colonization of the colon by enteric NCCs (ENCCs). We investigated the influence of the stiffness and structure of the environment on ENCC migration in vitro and during colonization of the gastrointestinal tract in chicken and mouse embryos. We showed using tensile stretching and atomic force microscopy (AFM) that the mesenchyme of the gut was initially soft but gradually stiffened during the period of ENCC colonization. Second-harmonic generation (SHG) microscopy revealed that this stiffening was associated with a gradual organization and enrichment of collagen fibers in the developing gut. Ex-vivo 2D cell migration assays showed that ENCCs migrated on substrates with very low levels of stiffness. In 3D collagen gels, the speed of the ENCC migratory front decreased with increasing gel stiffness, whereas no correlation was found between porosity and ENCC migration behavior. Metalloprotease inhibition experiments showed that ENCCs actively degraded collagen in order to progress. These results shed light on the role of the mechanical properties of tissues in ENCC migration during development. PMID:26887292

  9. How Tissue Mechanical Properties Affect Enteric Neural Crest Cell Migration

    NASA Astrophysics Data System (ADS)

    Chevalier, N. R.; Gazguez, E.; Bidault, L.; Guilbert, T.; Vias, C.; Vian, E.; Watanabe, Y.; Muller, L.; Germain, S.; Bondurand, N.; Dufour, S.; Fleury, V.

    2016-02-01

    Neural crest cells (NCCs) are a population of multipotent cells that migrate extensively during vertebrate development. Alterations to neural crest ontogenesis cause several diseases, including cancers and congenital defects, such as Hirschprung disease, which results from incomplete colonization of the colon by enteric NCCs (ENCCs). We investigated the influence of the stiffness and structure of the environment on ENCC migration in vitro and during colonization of the gastrointestinal tract in chicken and mouse embryos. We showed using tensile stretching and atomic force microscopy (AFM) that the mesenchyme of the gut was initially soft but gradually stiffened during the period of ENCC colonization. Second-harmonic generation (SHG) microscopy revealed that this stiffening was associated with a gradual organization and enrichment of collagen fibers in the developing gut. Ex-vivo 2D cell migration assays showed that ENCCs migrated on substrates with very low levels of stiffness. In 3D collagen gels, the speed of the ENCC migratory front decreased with increasing gel stiffness, whereas no correlation was found between porosity and ENCC migration behavior. Metalloprotease inhibition experiments showed that ENCCs actively degraded collagen in order to progress. These results shed light on the role of the mechanical properties of tissues in ENCC migration during development.

  10. How Tissue Mechanical Properties Affect Enteric Neural Crest Cell Migration.

    PubMed

    Chevalier, N R; Gazguez, E; Bidault, L; Guilbert, T; Vias, C; Vian, E; Watanabe, Y; Muller, L; Germain, S; Bondurand, N; Dufour, S; Fleury, V

    2016-01-01

    Neural crest cells (NCCs) are a population of multipotent cells that migrate extensively during vertebrate development. Alterations to neural crest ontogenesis cause several diseases, including cancers and congenital defects, such as Hirschprung disease, which results from incomplete colonization of the colon by enteric NCCs (ENCCs). We investigated the influence of the stiffness and structure of the environment on ENCC migration in vitro and during colonization of the gastrointestinal tract in chicken and mouse embryos. We showed using tensile stretching and atomic force microscopy (AFM) that the mesenchyme of the gut was initially soft but gradually stiffened during the period of ENCC colonization. Second-harmonic generation (SHG) microscopy revealed that this stiffening was associated with a gradual organization and enrichment of collagen fibers in the developing gut. Ex-vivo 2D cell migration assays showed that ENCCs migrated on substrates with very low levels of stiffness. In 3D collagen gels, the speed of the ENCC migratory front decreased with increasing gel stiffness, whereas no correlation was found between porosity and ENCC migration behavior. Metalloprotease inhibition experiments showed that ENCCs actively degraded collagen in order to progress. These results shed light on the role of the mechanical properties of tissues in ENCC migration during development. PMID:26887292

  11. Perturbation amplitude affects linearly estimated neuromechanical wrist joint properties.

    PubMed

    Klomp, Asbjorn; de Groot, Jurriaan H; de Vlugt, Erwin; Meskers, Carel G M; Arendzen, J Hans; van der Helm, Frans C T

    2014-04-01

    System identification techniques have been used to separate intrinsic muscular and reflexive contributions to joint impedance, which is an essential step in the proper choice of patient specific treatment. These techniques are, however, only well developed for linear systems. Assuming linearity prescribes the neuromuscular system to be perturbed only around predefined operating points. In this study, we test the validity of a commonly used linear model by analyzing the effects of flexion-extension displacement amplitude (2(°), 4(°), and 8(°)) on damping, stiffness, and reflex gain of the wrist joint, at different background torque levels (0, 1, and 2 N · m). With displacement amplitude, intrinsic damping increased, while intrinsic stiffness and reflex gains decreased. These changes were dependent on the level of wrist torque. The dependency of the neuromuscular system properties on even small variations in angular displacement is evident and has to be accounted for when comparing different studies and clinical interpretations using linear identification techniques. Knowledge of the behavior of the neuromuscular system around operating points is an essential step toward the development of nonlinear models that allow for discrimination between patients and controls in a larger range of loading conditions. PMID:24216632

  12. Size effects on the properties of high z scintillator materials

    NASA Astrophysics Data System (ADS)

    Hernandez-Sanchez, Bernadette A.; Boyle, Timothy J.; Villone, Janelle; Yang, Pin; Kinnan, Mark; Hoppe, Sarah; Thoma, Steve; Hattar, Khalid M.; Doty, F. P.

    2012-10-01

    Particle size effects of nano- and polycrystalline metal tungstate MWO4 (M = Ca, Pb, Cd) scintillators were examined through a comparison of commercially available powders and solution precipitation prepared nanoscaled materials. The scintillation behaviors of nanoparticles and commercial powders were examined with ion beam induced luminescence (IBIL), photoluminescence (PL), and cathodoluminescence (CL) spectroscopy techniques. For commercial microns sized MWO4 powders, spectral emission differences between CL and PL were only observed for Cd and Pb tungstates when compared to reported single crystals. The IBIL wavelength emissions also differed from the commercial MWO4 CL and PL data and were red shifted by 28 and 14 nm for CaWO4 and CdWO4; respectively, while PbWO4 had no significant change. IBIL analysis on CaWO4 nanoparticles produced a 40 nm blue shift from the commercial powder emission. These preliminary results suggest that both size and cation Z may affect the emission properties of the MWO4 scintillators.

  13. How does vacuum forming affect Pelite mechanical properties?

    PubMed

    Sanders, J E; Daly, C H

    1994-04-01

    Pelite is a polyethylene closed cell foam commonly used as an interface material in prosthetics. Both normal and vacuum-formed Pelite were tested under compression and under shear loading. For shear testing, the results were not significantly different for normal and vacuum-formed Pelite. For normal Pelite, the slope of the stress-strain curve was 1.17MPa (+/- 0.14) while for vacuum-formed Pelite it was 1.24MPa (+/- 0.22). Compressive results, however, were significantly different. Below 80kPa of applied compression, the slope of the stress-strain curve for normal Pelite was 0.99MPa (+/- 0.11) while for vacuum formed Pelite it was 0.72MPa (+/- 0.12). Between 80kPa and 200kPa of applied compression, the slope of the stress-strain curve for normal Pelite was 0.45MPa (+/- 0.03) while for vacuum formed Pelite it was 0.55MPa (+/- 0.05). Reasons for the differences and their significance to interface mechanics and computer-aided prosthesis design are discussed. PMID:8084749

  14. Characterization of the physical properties for solid granular materials

    SciTech Connect

    Tucker, Jonathan R.; Shadle, Lawrence J.; Guenther, Chris; Benyahia, Sofiane; Mei, Joseph S.; Banta, Larry

    2012-01-01

    Accurate prediction of the behavior of a system is strongly governed by the components within that system. For multiphase systems incorporating solid powder-like particles, there are many different physical properties which need to be known to some level of accuracy for proper design, modeling, or data analysis. In the past, the material properties were determined initially as a secondary part of the study or design. In an attempt to provide results with the least level of uncertainty, a procedure was developed and implemented to provide consistent analysis of several different types of materials. The properties that were characterized included particle sizing and size distributions, shape analysis, density (particle, skeletal and bulk), minimum fluidization velocities, void fractions, particle porosity, and assignment within the Geldart Classification. In the methods used for this experiment, a novel form of the Ergun equation was used to determine the bulk void fractions and particle density. Materials of known properties were initially characterized to validate the accuracy and methodology, prior to testing materials of unknown properties. The procedures used yielded valid and accurate results, with a high level of repeatability. A database of these materials has been developed to assist in model validation efforts and future designs. It is also anticipated that further development of these procedures wil be expanded increasing the properties included in the database.

  15. Chemical hydrogen storage material property guidelines for automotive applications

    SciTech Connect

    Semelsberger, Troy; Brooks, Kriston P.

    2015-04-01

    Chemical hydrogen storage is the sought after hydrogen storage media for automotive applications because of the expected low pressure operation (<20 atm), moderate temperature operation (<200 C), system gravimetric capacities (>0.05 kg H2/kg system), and system volumetric capacities (>0.05 kg H2/L system). Currently, the primary shortcomings of chemical hydrogen storage are regeneration efficiency, fuel cost and fuel phase (i.e., solid or slurry phase). Understanding the required material properties to meet the DOE Technical Targets for Onboard Hydrogen Storage Systems is a critical knowledge gap in the hydrogen storage research community. This study presents a set of fluid-phase chemical hydrogen storage material property guidelines for automotive applications meeting the 2017 DOE technical targets. Viable material properties were determined using a boiler-plate automotive system design. The fluid phase chemical hydrogen storage media considered in this study were neat liquids, solutions, and non-settling homogeneous slurries. Material properties examined include kinetics, heats of reaction, fuel-cell impurities, gravimetric and volumetric hydrogen storage capacities, and regeneration efficiency. The material properties, although not exhaustive, are an essential first step in identifying viable chemical hydrogen storage material propertiesdand most important, their implications on system mass, system volume and system performance.

  16. Acoustic properties and durability of liner materials at non-standard atmospheric conditions

    NASA Technical Reports Server (NTRS)

    Ahuja, K. K.; Gaeta, R. J., Jr.; Hsu, J. S.

    1994-01-01

    This report documents the results of an experimental study on how acoustic properties of certain absorbing liner materials are affected by nonstandard atmospheric conditions. This study was motivated by the need to assess risks associated with incorporating acoustic testing capability in wind tunnels with semicryogenic high Reynolds number aerodynamic and/or low pressure capabilities. The study consisted of three phases: 1) measurement of acoustic properties of selected liner materials at subatmospheric pressure conditions, 2) periodic cold soak and high pressure exposure of liner materials for 250 cycles, and 3) determination of the effect of periodic cold soak on the acoustic properties of the liner materials at subatmospheric conditions and the effect on mechanical resiliency. The selected liner materials were Pyrell foam, Fiberglass, and Kevlar. A vacuum facility was used to create the subatmospheric environment in which an impedance tube was placed to measure acoustic properties of the test materials. An automated cryogenic cooling system was used to simulate periodic cold soak and high pressure exposure. It was found that lower ambient pressure reduced the absorption effectiveness of the liner materials to varying degrees. Also no significant change in the acoustic properties occurred after the periodic cold soak. Furthermore, mechanical resiliency tests indicated no noticeable change.

  17. Models for predicting temperature dependence of material properties of aluminum

    NASA Astrophysics Data System (ADS)

    Marla, Deepak; Bhandarkar, Upendra V.; Joshi, Suhas S.

    2014-03-01

    A number of processes such as laser ablation, laser welding, electric discharge machining, etc involve high temperatures. Most of the processes involve temperatures much higher than the target melting and normal boiling point. Such large variation in target temperature causes a significant variation in its material properties. Due to the unavailability of experimental data on material properties at elevated temperatures, usually the data at lower temperatures is often erroneously extrapolated during modelling of these processes. Therefore, this paper attempts to evaluate the variation in material properties with temperature using some general and empirical theories, along with the available experimental data for aluminum. The evaluated properties of Al using the proposed models show a significant variation with temperature. Between room temperature and near-critical temperature (0.9Tc), surface reflectivity of Al varies from more than 90% to less than 50%, absorption coefficient decreases by a factor of 7, thermal conductivity decreases by a factor of 5, density decreases by a factor of 4, specific heat and latent heat of vapourization vary by a factor between 1.5 and 2. Applying these temperature-dependent material properties for modelling laser ablation suggest that optical properties have a greater influence on the process than thermophysical properties. The numerical predictions of the phase explosion threshold in laser ablation are within 5% of the experimental values.

  18. Determination of elastoplastic mechanical properties of the weld and heat affected zone metals in tailor-welded blanks by nanoindentation test

    NASA Astrophysics Data System (ADS)

    Ma, Xiangdong; Guan, Yingping; Yang, Liu

    2015-09-01

    The elastoplastic mechanical properties of the weld and heat affected zone metals have comparatively major impact on the forming process of tailor-welded blanks. A few scholars investigated the elastoplastic mechanical properties of the weld and heat affected zone, but they only simply assumed that it was a uniform distribution elastoplastic material different from the base materials. Four types of tailor-welded blanks which consist of ST12 and 304 stainless steel plates are selected as the research objects, the elastoplastic mechanical properties of the tailor-welded blanks weld and heat affected zone metals are obtained based on the nanoindentation tests, and the Erichsen cupping tests are conducted by combining numerical simulation with physical experiment. The nanoindentation tests results demonstrate that the elastoplastic mechanical properties of the weld and heat affected zone metals are not only different from the base materials, but also varying between the weld metals and the heat affected zone metals. Comparing the Erichsen cupping test resulted from numerical with that from experimental method, it is found that the numerical value of Erichsen cupping test which consider the elastoplastic mechanical properties of the weld and heat affected zone metals have a good agreement with the experimental result, and the relative error is only 4.8%. The proposed research provides good solutions for the inhomogeneous elastoplastic mechanical properties of the tailor-welded blanks weld and heat affected zone metals, and improves the control performance of tailor-welded blanks forming accuracy.

  19. Correlation of physical properties of ceramic materials with resistance to fracture by thermal shock

    NASA Technical Reports Server (NTRS)

    Lidman, W G; Bobrowsky, A R

    1949-01-01

    An analysis is made to determine which properties of materials affect their resistance to fracture by thermal stresses.From this analysis, a parameter is evaluated that is correlated with the resistance of ceramic materials to fracture by thermal shock as experimentally determined. This parameter may be used to predict qualitatively the resistance of a material to fracture by thermal shock. Resistance to fracture by thermal shock is shown to be dependent upon the following material properties: thermal conductivity, tensile strength, thermal expansion, and ductility modulus. For qualitative prediction of resistance of materials to fracture by thermal shock, the parameter may be expressed as the product of thermal conductivity and tensile strength divided by the product of linear coefficient of thermal expansion and ductility modulus of the specimen.

  20. MPOD: A Material Property Open Database linked to structural information

    NASA Astrophysics Data System (ADS)

    Pepponi, Giancarlo; Gražulis, Saulius; Chateigner, Daniel

    2012-08-01

    Inspired by the Crystallography Open Database (COD), the Material Properties Open Database (MPOD) was given birth. MPOD aims at collecting and making publicly available at no charge tensorial properties (including scalar properties) of phases and linking such properties to structural information of the COD when available. MPOD files are written with the STAR file syntax, used and developed for the Crystallographic Information Files. A dictionary containing new definitions has been written according to the Dictionary Definition Language 1, although some tricks were adopted to allow for multiple entries still avoiding ambiguousness. The initial set includes mechanical properties, elastic stiffness and compliance, internal friction; electrical properties, resistivity, dielectric permittivity and stiffness, thermodynamic properties, heat capacity, thermal conductivity, diffusivity and expansion; electromechanical properties, piezoelectricity, electrostriction, electromechanical coupling; optical properties; piezooptic and photoelastic properties; superconducting properties, critical fields, penetration and coherence lengths. Properties are reported in MPOD files where the original published paper containing the data is cited and structural and experimental information is also given. One MPOD file contains information relative to only one publication and one phase. The files and the information contained therein can also be consulted on-line at http://www.materialproperties.org.

  1. Interactions between organisms and parent materials of a constructed Technosol shape its hydrostructural properties

    NASA Astrophysics Data System (ADS)

    Deeb, Maha; Grimaldi, Michel; Lerch, Thomas Z.; Pando, Anne; Gigon, Agnès; Blouin, Manuel

    2016-04-01

    There is no information on how organisms influence hydrostructural properties of constructed Technosols and how such influence will be affected by the parent-material composition factor. In a laboratory experiment, parent materials, which were excavated deep horizons of soils and green waste compost (GWC), were mixed at six levels of GWC (from 0 to 50 %). Each mixture was set up in the presence/absence of plants and/or earthworms, in a full factorial design (n = 96). After 21 weeks, hydrostructural properties of constructed Technosols were characterized by soil shrinkage curves. Organisms explained the variance of hydrostructural characteristics (19 %) a little better than parent-material composition (14 %). The interaction between the effects of organisms and parent-material composition explained the variance far better (39 %) than each single factor. To summarize, compost and plants played a positive role in increasing available water in macropores and micropores; plants were extending the positive effect of compost up to 40 and 50 % GWC. Earthworms affected the void ratio for mixtures from 0 to 30 % GWC and available water in micropores, but not in macropores. Earthworms also acted synergistically with plants by increasing their root biomass, resulting in positive effects on available water in macropores. Organisms and their interaction with parent materials positively affected the hydrostructural properties of constructed Technosols, with potential positive consequences on resistance to drought or compaction. Considering organisms when creating Technosols could be a promising approach to improve their fertility.

  2. A Summary of the Fatigue Properties of Wind Turbine Materials

    SciTech Connect

    SUTHERLAND, HERBERT J.

    1999-10-07

    Modern wind turbines are fatigue critical machines that are typically used to produce electrical power from the wind. The materials used to construct these machines are subjected to a unique loading spectrum that contains several orders of magnitude more cycles than other fatigue critical structures, e.g., an airplane. To facilitate fatigue designs, a large database of material properties has been generated over the past several years that is specialized to materials typically used in wind turbines. In this paper, I review these fatigue data. Major sections are devoted to the properties developed for wood, metals (primarily aluminum) and fiberglass. Special emphasis is placed on the fiberglass discussion because this material is current the material of choice for wind turbine blades. The paper focuses on the data developed in the U.S., but cites European references that provide important insights.

  3. Corrosion properties of second-generation conductive materials

    NASA Technical Reports Server (NTRS)

    Groshart, E.

    1984-01-01

    Since the introduction of silver-filled epoxy adhesives and silver-filled nitrocellulose lacquer as RFI control materials, a number of new materials have been introduced. The resin carriers have been changed in an effort to make the materials more usable or more EPA acceptable and the fillers have been varied in an effort to make the materials less costly. The corrosion-related properties of second-generation materials were assessed, including adhesives, caulks, and greases. Aluminum 2024 was used as the only substrate material. Ten days of salt fog was used as the corrosive environment. If a noble material such as silver, nickel, or carbon is sandwiched with aluminum an increase in dc resistance results given enough time. If this is unsatisfactory electrically it should either not be used or have all corrosive environments excluded.

  4. Optical method for determining the mechanical properties of a material

    DOEpatents

    Maris, H.J.; Stoner, R.J.

    1998-12-01

    Disclosed is a method for characterizing a sample, comprising the steps of: (a) acquiring data from the sample using at least one probe beam wavelength to measure, for times less than a few nanoseconds, a change in the reflectivity of the sample induced by a pump beam; (b) analyzing the data to determine at least one material property by comparing a background signal component of the data with data obtained for a similar delay time range from one or more samples prepared under conditions known to give rise to certain physical and chemical material properties; and (c) analyzing a component of the measured time dependent reflectivity caused by ultrasonic waves generated by the pump beam using the at least one determined material property. The first step of analyzing may include a step of interpolating between reference samples to obtain an intermediate set of material properties. The material properties may include sound velocity, density, and optical constants. In one embodiment, only a correlation is made with the background signal, and at least one of the structural phase, grain orientation, and stoichiometry is determined. 14 figs.

  5. Optical method for determining the mechanical properties of a material

    DOEpatents

    Maris, Humphrey J.; Stoner, Robert J.

    1998-01-01

    Disclosed is a method for characterizing a sample, comprising the steps of: (a) acquiring data from the sample using at least one probe beam wavelength to measure, for times less than a few nanoseconds, a change in the reflectivity of the sample induced by a pump beam; (b) analyzing the data to determine at least one material property by comparing a background signal component of the data with data obtained for a similar delay time range from one or more samples prepared under conditions known to give rise to certain physical and chemical material properties; and (c) analyzing a component of the measured time dependent reflectivity caused by ultrasonic waves generated by the pump beam using the at least one determined material property. The first step of analyzing may include a step of interpolating between reference samples to obtain an intermediate set of material properties. The material properties may include sound velocity, density, and optical constants. In one embodiment, only a correlation is made with the background signal, and at least one of the structural phase, grain orientation, and stoichiometry is determined.

  6. Neural networks as tools for predicting materials properties

    SciTech Connect

    Sumpter, B.G.; Noid, D.W.

    1995-12-31

    Materials science is of fundamental significance to science and technology because our industrial base and society depend upon our ability to develop advanced materials. Materials and materials processing cuts across almost every sector of industry. The key in all of these areas is the ability to rapidly screen possible designs which will have significant impact. However up to now materials design and processing have been to a large extent empirical sciences. In addition we are still unable to design new alloys and polymers to meet application specific requirements. Being able to do so quickly and at minimum cost would provide an incredible advantage. Obviously, the ability to predict physical, chemical, or mechanical properties of compounds prior to their synthesis is of great technological value in optimizing their design, processing, or recycling. In addition, in order to realize the ultimate goal of materials by computational design, the reverse problem, prediction of chemical structure based on desired properties, has to be resolved. Research at ORNL has lead to the development of a novel computational paradigm (coupling computational neural networks with graph theory, genetic algorithms, wavelet theory, fuzzy logic, molecular dynamics, and quantum chemistry) capable of performing accurate computational synthesis (both predictions of properties or the design of compounds that have specified performance criteria). The computational paradigm represents a hybrid of a number of emerging technologies and has proven to work very well for test compounds ranging from small organic molecules to polymeric materials. Fundamental to the method is the neural network-based formulation of the correlations between structure and properties. The advantages of this method is in its ease of use, speed, accuracy, and that it can be used to predict both properties from structure, and also structure from properties.

  7. High-rate mechanical properties of energetic materials

    NASA Astrophysics Data System (ADS)

    Walley, S. M.; Siviour, C. R.; Drodge, D. R.; Williamson, D. M.

    2010-01-01

    Compared to the many thousands of studies that have been performed on the energy release mechanisms of high energy materials, relatively few studies have been performed (a few hundred) into their mechanical properties. Since it is increasingly desired to model the high rate deformation of such materials, it is of great importance to gather data on their response so that predictive constitutive models can be constructed. This paper reviews the state of the art concerning what is known about the mechanical response of high energy materials. Examples of such materials are polymer bonded explosives (used in munitions), propellants (used to propel rockets), and pyrotechnics (used to initiate munitions and also in flares).

  8. Mechanical Properties of Nanostructured Materials Determined Through Molecular Modeling Techniques

    NASA Technical Reports Server (NTRS)

    Clancy, Thomas C.; Gates, Thomas S.

    2005-01-01

    The potential for gains in material properties over conventional materials has motivated an effort to develop novel nanostructured materials for aerospace applications. These novel materials typically consist of a polymer matrix reinforced with particles on the nanometer length scale. In this study, molecular modeling is used to construct fully atomistic models of a carbon nanotube embedded in an epoxy polymer matrix. Functionalization of the nanotube which consists of the introduction of direct chemical bonding between the polymer matrix and the nanotube, hence providing a load transfer mechanism, is systematically varied. The relative effectiveness of functionalization in a nanostructured material may depend on a variety of factors related to the details of the chemical bonding and the polymer structure at the nanotube-polymer interface. The objective of this modeling is to determine what influence the details of functionalization of the carbon nanotube with the polymer matrix has on the resulting mechanical properties. By considering a range of degree of functionalization, the structure-property relationships of these materials is examined and mechanical properties of these models are calculated using standard techniques.

  9. Development and Demonstration of Material Properties Database and Software for the Simulation of Flow Properties in Cementitious Materials

    SciTech Connect

    Smith, F.; Flach, G.

    2015-03-30

    This report describes work performed by the Savannah River National Laboratory (SRNL) in fiscal year 2014 to develop a new Cementitious Barriers Project (CBP) software module designated as FLOExcel. FLOExcel incorporates a uniform database to capture material characterization data and a GoldSim model to define flow properties for both intact and fractured cementitious materials and estimate Darcy velocity based on specified hydraulic head gradient and matric tension. The software module includes hydraulic parameters for intact cementitious and granular materials in the database and a standalone GoldSim framework to manipulate the data. The database will be updated with new data as it comes available. The software module will later be integrated into the next release of the CBP Toolbox, Version 3.0. This report documents the development efforts for this software module. The FY14 activities described in this report focused on the following two items that form the FLOExcel package; 1) Development of a uniform database to capture CBP data for cementitious materials. In particular, the inclusion and use of hydraulic properties of the materials are emphasized; and 2) Development of algorithms and a GoldSim User Interface to calculate hydraulic flow properties of degraded and fractured cementitious materials. Hydraulic properties are required in a simulation of flow through cementitious materials such as Saltstone, waste tank fill grout, and concrete barriers. At SRNL these simulations have been performed using the PORFLOW code as part of Performance Assessments for salt waste disposal and waste tank closure.

  10. Design of meta-materials with novel thermoelastic properties

    NASA Astrophysics Data System (ADS)

    Watts, Seth

    The development of new techniques in micro-manufacturing in recent years has enabled the fabrication of material microstructures with essentially arbitrary designs, including those with multiple constituent materials and void space in nearly any geometry. With an essentially open design space, the onus is now on the engineer to design composite materials which are optimal for their purpose. These new materials, called meta-materials or materials with architected microstructures, offer the potential to mix and match properties in a way that exceeds that of traditional composites. We concentrate on the thermal and elastic properties of isotropic meta-materials, and design microstructures with combinations of Young's modulus, Poisson's ratio, thermal conductivity, thermal expansion, and mass density which are not found among naturally-occurring or traditional composite materials. We also produce designs with thermal expansion far below other materials. We use homogenization theory to predict the material properties of a bulk meta-material comprised of a periodic lattice of unit cells, then use topology optimization to rearrange two constituent materials and void space within the unit cell in order to extremize an objective function which yields the combinations of properties we seek. This method is quite general and can be extended to consider additional properties of interest. We constrain the design space to satisfy material isotropy directly (2D), or to satisfy cubic symmetry (3D), from which point an isotropy constraint function is easily applied. We develop and use filtering, nonlinear interpolation, and thresholding methods to render the design problem well-posed, and as a result ensure our designs are manufacturable. We have written two computer implementations of this design methodology. The first is for creating two-dimensional designs, which can run on a serial computer in approximately half an hour. The second is a parallel implementation to allow

  11. Flow-induced properties of nanotube-filled polymer materials.

    PubMed

    Kharchenko, Semen B; Douglas, Jack F; Obrzut, Jan; Grulke, Eric A; Migler, Kalman B

    2004-08-01

    Carbon nanotubes (CNTs) are under intense investigation in materials science owing to their potential for modifying the electrical conductivity sigma, shear viscosity eta, and other transport properties of polymeric materials. These particles are hybrids of filler and nanoscale additives because their lengths are macroscopic whereas their cross-sectional dimensions are closer to molecular scales. The combination of extended shape, rigidity and deformability allows CNTs to be mechanically dispersed in polymer matrices in the form of disordered 'jammed' network structures. Our measurements on representative network-forming multiwall nanotube (MWNT) dispersions in polypropylene indicate that these materials exhibit extraordinary flow-induced property changes. Specifically, sigma and eta both decrease strongly with increasing shear rate, and these nanocomposites exhibit impressively large and negative normal stress differences, a rarely reported phenomenon in soft condensed matter. We illustrate the practical implications of these nonlinear transport properties by showing that MWNTs eliminate die swell in our nanocomposites, an effect crucial for their processing. PMID:15273745

  12. Control over magnetic properties in bulk hybrid materials

    NASA Astrophysics Data System (ADS)

    Urban, Christian; Quesada, Adrian; Saerbeck, Thomas; Rubia, Miguel Angel De La; Garcia, Miguel Angel; Fernandez, Jose Francisco; Schuller, Ivan K.; UCSD Collaboration; Instituto de Ceramica, Madrid Collaboration; Institut Laue-Langevin, Grenoble Collaboration

    We present control of coercivity and remanent magnetization of a bulk ferromagnetic material embedded in bulk vanadium sesquioxide (V2O3) by using a standard bulk synthesis procedure. The method generalizes the use of structural phase transitions of one material to control structural and magnetic properties of another. A structural phase transition (SPT) in the V2O3 host material causes magnetic properties of Ni to change as function of temperature. The remanent magnetization and the coercivity are reversibly controlled by the SPT without additional external magnetic fields. The reversible tuning shown here opens the pathway for controlling the properties of a vast variety of magnetic hybrid bulk systems. This Work is supported by the Office of Basic Energy Science, U.S. Department of Energy, BES-DMS funded by the Department of Energy's Office of Basic Energy Science, DMR under grant DE FG02 87ER-45332.

  13. Chemistry and properties of blends of acetylene terminated materials

    NASA Technical Reports Server (NTRS)

    Connell, John W.; Hergenrother, Paul M.

    1991-01-01

    As part of a NASA program to develop new high temperature/high performance structural materials, the chemistry and properties of acetylene-containing materials and their cured resins are under investigation. The objective of this work is to develop materials that are readily processable (i.e., 200-300 C and about 1.4 MPa or less) and possess usable mechanical properties at temperatures as high as 177 C. An acetylene-terminated aspartimide (ATA) was blended with an equal weight of an acetylene-terminated arylene ether (ATAE) oligomer. The blend was subsequently thermally cured to yield a resin which was evaluated in the form of neat resin moldings, adhesive specimens, and laminates. Adhesive specimens and laminates gave good mechanical properties to temperatures as high as 177 C. In addition, preliminary laminate work is presented on the resin from a blend of a new N-methyl substituted ATA and an ATAE.

  14. Study of the effect of properties of material on vacuum breakdown initiated by laser radiation

    SciTech Connect

    Seleznev, V. P.; Revazov, V. O.

    2015-12-15

    In this work, the effect of various properties of materials on vacuum breakdown initiated by laser radiation is considered. Estimating calculations are performed which show that the material of the target electrode distinctly affects the minimum energy of laser radiation needed for igniting a vacuum spark. The experimental studies carried out confirm the estimating calculations, and a number of materials are revealed which can be arranged in order of increase in the energy needed for the formation of breakdown in vacuum by the impact of a laser pulse.

  15. Atomistic methodologies for material properties of 2D materials at the nanoscale

    NASA Astrophysics Data System (ADS)

    Zhang, Zhen

    Research on two dimensional (2D) materials, such as graphene and MoS2, now involves thousands of researchers worldwide cutting across physics, chemistry, engineering and biology. Due to the extraordinary properties of 2D materials, research extends from fundamental science to novel applications of 2D materials. From an engineering point of view, understanding the material properties of 2D materials under various conditions is crucial for tailoring the electrical and mechanical properties of 2D-material-based devices at the nanoscale. Even at the nanoscale, molecular systems typically consist of a vast number of atoms. Molecular dynamics (MD) simulations enable us to understand the properties of assemblies of molecules in terms of their structure and the microscopic interactions between them. From a continuum approach, mechanical properties and thermal properties, such as strain, stress, and heat capacity, are well defined and experimentally measurable. In MD simulations, material systems are considered to be discrete, and only interatomic potential, interatomic forces, and atom positions are directly obtainable. Besides, most of the fracture mechanics concepts, such as stress intensity factors, are not applicable since there is no singularity in MD simulations. However, energy release rate still remains to be a feasible and crucial physical quantity to characterize the fracture mechanical property of materials at the nanoscale. Therefore, equivalent definition of a physical quantity both in atomic scale and macroscopic scale is necessary in order to understand molecular and continuum scale phenomena concurrently. This work introduces atomistic simulation methodologies, based on interatomic potential and interatomic forces, as a tool to unveil the mechanical properties, thermal properties and fracture mechanical properties of 2D materials at the nanoscale. Among many 2D materials, graphene and MoS2 have attracted intense interest. Therefore, we applied our

  16. Micro-mechanical properties of bio-materials

    NASA Astrophysics Data System (ADS)

    Zakiev, V.; Markovsky, A.; Aznakayev, E.; Zakiev, I.; Gursky, E.

    2005-09-01

    Investigation of physical-mechanical characteristics of stomatologic materials (ceramics for crowns, silver amalgam, cements and materials on a polymeric basis) properties by the modern methods and correspondence their physical-mechanical properties to the physical-mechanical properties of native teeth is represented. The universal device "Micron-Gamma" is built for this purpose. This device allows investigate the physical-mechanical characteristics of stomatologic materials (an elastic modulus, micro-hardness, destruction energy, resistance to scratching) by the methods of continuous indentation, scanning and pricking. A new effective method as well as its device application for the investigation of surface layers of materials and their physical-mechanical properties by means of the constant indenting of an indenter is realized. This method is based on the automatic registration of loading (P) on the indenter with the simultaneous measurement of its indentation depth (h). The results of investigations are presented on a loading diagram P=f(h) and as a digital imaging on the PC. This diagram allows get not only more diverse characteristics in the real time regime but also gives new information about the stomatologic material properties. Therefore, we can to investigate the wide range of the physical-mechanical properties of stomatologic materials. "Micron-alpha" is digital detection device for light imaging applications. It enables to detect the very low material surface relief heights and restoration of surface micro topography by a sequence data processing of interferential data of partially coherent light also. "Micron-alpha" allows: to build 2D and 3D imaging of a material surface; to estimate the quantitatively characteristics of a material surface; to observe the imaging interferential pictures both in the white and in the monochromatic light; to carry out the investigation of blood cells, microbes and biological macromolecules profiles. The method allows

  17. Affective Properties of Mothers' Speech to Infants with Hearing Impairment and Cochlear Implants

    ERIC Educational Resources Information Center

    Kondaurova, Maria V.; Bergeson, Tonya R.; Xu, Huiping; Kitamura, Christine

    2015-01-01

    Purpose: The affective properties of infant-directed speech influence the attention of infants with normal hearing to speech sounds. This study explored the affective quality of maternal speech to infants with hearing impairment (HI) during the 1st year after cochlear implantation as compared to speech to infants with normal hearing. Method:…

  18. Psychometric Properties of the Affect Intensity and Reactivity Measure Adapted for Youth (AIR-Y)

    ERIC Educational Resources Information Center

    Jones, Rachel E.; Leen-Feldner, Ellen W.; Olatunji, Bunmi O.; Reardon, Laura E.; Hawks, Erin

    2009-01-01

    A valid and reliable instrument for measuring affect intensity does not exist for adolescents; such a measure may help to refine understanding of emotion among youths. The purpose of the current study was to evaluate the psychometric properties and clinical relevance of a measure of affect intensity adapted for youths. Two hundred five community…

  19. Wetting properties of molten carbonate fuel cell electrode materials

    SciTech Connect

    Fisher, J.M.; Bennett, P.S.; Pignon, J.F. ); Makkus, R.C.; Weewer, R.; Hemmes, K. )

    1990-05-01

    Molten carbonate fuel cells (MCFC) are of interest for their potentially highly efficient conversion of chemical energy into electrical energy. This paper discusses how the wetting properties of electrode materials by molten carbonate have a high relevance for the performance of the porous electrodes. When internal reforming of the fuel gas at the anode is performed, the wetting properties also influence the efficiency of the reforming process. Distribution of the electrolyte in an MCFC stack is mainly determined by the wetting properties of the porous MCFC materials, such as electrodes and tile in contact with the electrolyte. The quality of the wet seal areas of the separator plates in an MCFC stack to prevent gas leakage also depends on the wetting properties.

  20. Room temperature mechanical properties of shuttle thermal protection system materials

    NASA Technical Reports Server (NTRS)

    Sawyer, J. W.; Rummler, D. R.

    1980-01-01

    Tests were conducted at room temperature to determine the mechanical properties and behavior of materials used for the thermal protection system of the space shuttle. The materials investigated include the LI-900 RSI tiles, the RTV-560 adhesive and the .41 cm (.16 thick) strain isolator pad (SIP). Tensile and compression cyclic loading tests were conducted on the SIP material and stress-strain curves obtained for various proof loads and load cyclic conditioning. Ultimate tensile and shear tests were conducted on the RSI, RTV, and SIP materials. The SIP material exhibits highly nonlinear stress-strain behavior, increased tangent modulus and ultimate tensile strength with increased loading rate, and large short time load relaxation and moderate creep behavior. Proof and cyclic load conditioning of the SIP results in permanent deformation of the material, hysteresis effects, and much higher tensile tangent modulus values at large strains.

  1. Large scale Hugoniot material properties for Danby Marble

    SciTech Connect

    Rinehart, E.J.

    1993-11-01

    This paper presents the results of simulation experiments of nuclear underground testing carried out using the HYDROPLUS methodology for yield verifications of non-standard tests. The objective of this test series was to demonstrate the accuracy of stress and velocity measurements in hard, low porosity rock, to obtain comparisons of large-scale material properties with those obtained from laboratory testing of the same material, and to address the problems posed by a material having a clear precursor wave preceding the main shock wave. The test series consisted of three individual experimental tests. The first established material properties of the Danby marble selected for use in the experiments. The second and third tests looked at stress and velocity gage errors obtained when gages were placed in boreholes and grouted into place.

  2. Fabrication, properties, and tritium recovery from solid breeder materials

    SciTech Connect

    Johnson, C.E. ); Kondo, T. ); Roux, N. ); Tanaka, S. ); Vollath, D. )

    1991-01-01

    The breeding blanket is a key component of the fusion reactor because it directly involves tritium breeding and energy extraction, both of which are critical to development of fusion power. The lithium ceramics continue to show promise as candidate breeder materials. This promise was recognized by the International Thermonuclear Experimental Reactor (ITER) design team in its selection of ceramics as the first option for the ITER breeder material. Blanket design studies have indicated properties in the candidate materials data base that need further investigation. Current studies are focusing on tritium release behavior at high burnup, changes in thermophysical properties with burnup, compatibility between the ceramic breeder and beryllium multiplier, and phase changes with burnup. Laboratory and in-reactor tests, some as part of an international collaboration for development of ceramic breeder materials, are underway. 133 refs., 1 fig.

  3. Fibrous random materials: From microstructure to macroscopic properties

    NASA Astrophysics Data System (ADS)

    Yazdchi, K.; Luding, S.

    2013-06-01

    Fibrous porous materials are involved in a wide range of applications including composite materials, fuel cells, heat exchangers and (biological)filters. Fluid flow through these materials plays an important role in many engineering applications and processes, such as textiles and paper manufacturing or transport of (under)ground water and pollutants. While most porous materials have complex geometry, some can be seen as two-dimensional particulate/fibrous systems, in which we introduce several microscopic quantities, based on Voronoi and Delaunay tessellations, to characterize their microstructure. In particular, by analyzing the topological properties of Voronoi polygons, we observe a smooth transition from disorder to order, for increasing packing fraction. Using fully resolved finite element (FE) simulations of Newtonian, incompressible fluid flow perpendicular to the fibres, the macroscopic permeability is calculated in creeping flow regimes. The effect of fibre arrangement and local crystalline regions on the macroscopic permeability is discussed and the macroscopic property is linked to the microscopic structural quantities.

  4. Reflector and Shield Material Properties for Project Prometheus

    SciTech Connect

    J. Nash

    2005-11-02

    This letter provides updated reflector and shield preliminary material property information to support reactor design efforts. The information provided herein supersedes the applicable portions of Revision 1 to the Space Power Program Preliminary Reactor Design Basis (Reference (a)). This letter partially answers the request in Reference (b) to provide unirradiated and irradiated material properties for beryllium, beryllium oxide, isotopically enriched boron carbide ({sup 11}B{sub 4}C) and lithium hydride. With the exception of {sup 11}B{sub 4}C, the information is provided in Attachments 1 and 2. At the time of issuance of this document, {sup 11}B{sub 4}C had not been studied.

  5. Characterization of Viscoelastic Properties of Polymeric Materials Through Nanoindentation

    NASA Technical Reports Server (NTRS)

    Odegard, G. M.; Bandorawalla, T.; Herring, H. M.; Gates, T. S.

    2003-01-01

    Nanoindentation is used to determine the dynamic viscoelastic properties of six polymer materials. It is shown that varying the harmonic frequency of the nanoindentation does not have any significant effect on the measured storage and loss moduli of the polymers. Agreement is found between these results and data from DMA testing of the same materials. Varying the harmonic amplitude of the nanoindentation does not have a significant effect on the measured properties of the high performance resins, however, the storage modulus of the polyethylene decreases as the harmonic amplitude increases. Measured storage and loss moduli are also shown to depend on the density of the polyethylene.

  6. Material Property Characterization of AS4/VRM-34 Textile Laminates

    NASA Technical Reports Server (NTRS)

    Grenoble, Ray W.; Johnston, William M

    2013-01-01

    Several material properties (modulus, strengths, and fracture toughness) of a textile composite have been evaluated to provide input data to analytical models of Pultruded Rod Stiffened Efficient Unitized Structure (PRSEUS). The material system is based on warp-knitted preforms of AS4 carbon fibers and VRM-34 epoxy resin, which have been processed via resin infusion and oven curing. Tensile, compressive, shear, and fracture toughness properties have been measured at ambient and elevated temperatures. All specimens were tested in as-fabricated (dry) condition. Specimens were tested with and without through-thickness stitching.

  7. Cyclic material properties tests supporting elastic-plastic analysis development

    SciTech Connect

    Hodge, S.C.; Minicucci, J.M.

    1996-11-01

    Correlation studies have shown that hardening models currently available in the ABAQUS finite element code (isotropic, kinematic) do not accurately capture the inelastic strain reversals that occur due to structural rebounding from a rapidly applied transient dynamic load. The purpose of the Cyclic Material properties Test program was to obtain response data for the first several cycles of inelastic strain reversal from a cyclic properties test. This data is needed to develop elastic-plastic analysis methods that can accurately predict strains and permanent sets in structures due to rapidly applied transient dynamic loading. Test specimens were cycled at inelastic strain levels typical of rapidly applied transient dynamic analyses (0.5% to 4.0%). In addition to the inelastic response data, cyclic material properties for high yield strength (80 ksi) steel were determined including a cyclic stress-strain curve for a stabilized specimen. Two test methods, the Incremental Step method and the Companion specimen Method, were sued to determine cyclic properties. The incrementally decreasing strain amplitudes in the first loading block of the Incremental Step method test is representative of the response of structures subjected to rapidly applied transient dynamic loads. The inelastic strain history data generated by this test program will be used to support development of a material model that can accurately predict inelastic material behavior including inelastic strain reversals. Additionally, this data can be used to verify material model enhancements to elastic-plastic finite element analysis codes.

  8. Means for ultrasonic testing when material properties vary

    DOEpatents

    Beller, Laurence S.

    1979-01-01

    A device is provided for maintaining constant sensitivity in an ultrasonic testing device, despite varying attenuation due to the properties of the material being tested. The device includes a sensor transducer for transmitting and receiving a test signal and a monitor transducer positioned so as to receive ultrasonic energy transmitted through the material to be tested. The received signal of the monitor transducer is utilized in analyzing data obtained from the sensor transducer.

  9. Database for the Tribological Properties of Self-Lubricating Materials

    NASA Technical Reports Server (NTRS)

    Jett, T. R.; Thom, R. L.

    1998-01-01

    A test program to determine the tribological properties of several self-lubricating composites was performed. Testing was done using an LFW-1 Friction and Wear machine. Each material was tested at four load levels (66 N, 133 N, 266 N, and 400 N) under ambient conditions. The coefficient of friction and wear rate was determined for each material, and a relative ranking of the composites was made.

  10. Electron paramagnetic resonance of material properties and processes

    SciTech Connect

    Brower, K. L.

    1980-01-01

    This paper demonstrates, primarily for the non-specialist and within the context of new and recent achievements, the diagnostic value of electron paramagnetic resonance (EPR) in the study of material properties and processes. I have selected three EPR studies which demonstrate the elegance and uniqueness of EPR in atomic defect studies and exemplify unusual achievements through the use of new techniques for material measurement and preparation. A brief introduction into the origin, interaction, and detection of unpaired electrons is included.

  11. Material properties and fracture mechanics in relation to ceramic machining

    SciTech Connect

    Griffith, L.V.

    1993-12-02

    Material removal rate, surface finish, and subsurface damage are largely governed by fracture mechanics and plastic deformation, when ceramics are machined using abrasive methods. A great deal of work was published on the fracture mechanics of ceramics in the late 1970s and early 1980s, although this work has never resulted in a comprehensive model of the fixed abrasive grinding process. However, a recently published model describes many of the most important features of the loose abrasive machining process, for example depth of damage, surface roughness, and material removal rate. Many of the relations in the loose abrasive machining model can be readily discerned from fracture mechanics models, in terms of material properties. By understanding the mechanisms of material removal, from a material properties perspective, we can better estimate how one material will machine in relation to another. Although the fracture mechanics models may have been developed for loose abrasive machining, the principles of crack initiation and propagation are equally valuable for fixed abrasive machining. This report provides a brief review of fracture in brittle materials, the stress distribution induced by abrasives, critical indenter loads, the extension of cracks, and the relation of the fracture process to material removal.

  12. Characterization of mechanical properties of materials using ultrasound broadband spectroscopy.

    PubMed

    Agrawal, Megha; Prasad, Abhinav; Bellare, Jayesh R; Seshia, Ashwin A

    2016-01-01

    This article explores the characterization of homogenous materials (metals, alloys, glass and polymers) by a simple broadband ultrasonic interrogation method. The novelty lies in the use of ultrasound in a continuous way with very low input power (0 dBm or less) and analysis of the transmitted acoustic wave spectrum for material property characterization like speed of sound, density and dimensions of a material. Measurements were conducted on various thicknesses of samples immersed in liquid where continuous-wave, frequency swept ultrasonic energy was incident normal to the sample surface. The electro-acoustic transmission response is analyzed in the frequency domain with respect to a specifically constructed multi-layered analytical model. From the acoustic signature of the sample materials, material properties such as speed of sound and acoustic impedance can be calculated with experimentally derived values found to be in general agreement with the literature and with pulse-echo technique establishing the basis for a non-contact and non-destructive technique for material characterization. Further, by looking at the frequency spacing of the peaks of water when the sample is immersed, the thickness of the sample can be calculated independently from the acoustic response. This technique can prove to be an effective non-contact, non-destructive and fast material characterization technique for a wide variety of materials. PMID:26387979

  13. Method of varying a physical property of a material through its depth

    DOEpatents

    Daniel, Claus

    2015-04-21

    A method is disclosed for varying a mechanical property of a material at two depths. The method involves the application of at least two laser pulses of different durations. The method involves a determination of the density of the material from the surface to each depth, a determination of the heat capacity of the material from the surface to each depth, and a determination of the thermal conductivity of the material from the surface to each depth. Each laser pulse may affect the density, heat capacity, and thermal conductivity of the material, so it may be necessary to re-evaluate those parameters after each laser pulse and prior to the next pulse. The method may be applied to implantation materials to improve osteoblast and osteoclast activity.

  14. Molecular properties of polymeric materials for space applications

    NASA Technical Reports Server (NTRS)

    Harries, Wynford L.; Kern, Kristen T.; Stancil, Phillip C.

    1992-01-01

    This cooperative agreement was intended to investigate the effects of a space environment on the properties of polymeric materials. In addition, efforts have been made to understand and investigate environment simulation techniques and test methodology. The results identified the changes in the properties of six aerospace structural adhesives, three neat high polymers, and two fiber-reinforced polymers, as caused by exposure to four simulated space environmental conditions. Significant property changes occurred for several of the systems as a result of one or more of the exposures. A summary of the research follows a list of related publications and presentations.

  15. Effective Mechanical Properties of Lattice Material Fabricated by Material Extrusion Additive Manufacturing

    SciTech Connect

    Park, Sang-In; Choi, Seung-kyum; Rosen, David W; Duty, Chad E

    2014-01-01

    In this paper, a two-step homogenization method is proposed and implemented for evaluating effective mechanical properties of lattice structured material fabricated by the material extrusion additive manufacturing process. In order to consider the characteristics of the additive manufacturing process in estimation procedures, the levels of scale for homogenization are divided into three stages the levels of layer deposition, structural element, and lattice structure. The method consists of two transformations among stages. In the first step, the transformation between layer deposition and structural element levels is proposed to find the geometrical and material effective properties of structural elements in the lattice structure. In the second step, the method to estimate effective mechanical properties of lattice material is presented, which uses a unit cell and is based on the discretized homogenization method for periodic structure. The method is implemented for cubic lattice structure and compared to experimental results for validation purposes.

  16. Reactor Materials Program: Mechanical properties of irradiated Types 304 and 304L stainless steel weldment components

    SciTech Connect

    Sindelar, R.L.; Caskey, G.R. Jr.

    1991-12-01

    The vessels (reactor tanks) of the Savannah River Site nuclear production reactors constructed in the 1950's are comprised of Type 304 stainless steel with Type 308 stainless steel weld filler. Irradiation exposure to the reactor tank sidewalls through reactor operation has caused a change in the mechanical properties of these materials. A database of as-irradiated mechanical properties for site-specific materials and irradiation conditions has been produced for reactor tank structural analyses and to quantify the effects of radiation-induced materials degradation for evaluating reactor service life. The data has been collected from the SRL Reactor Materials Program (RMP) irradiations and testing of archival stainless steel weldment components and from previous SRL programs to measure properties of irradiated reactor Thermal Shield weldments and reactor tank (R-tank) sidewall material. Irradiation programs of the RMP are designed to quantify mechanical properties at tank operating temperatures following irradiation to present and future tank wall maximum exposure conditions. The exposure conditions are characterized in terms of fast neutron fluence (E{sub n} > 0.1 MeV) and displacements per atom (dpa){sup 3}. Tensile properties, Charpy-V notch toughness, and elastic-plastic fracture toughness were measured for base, weld, and weld heat-affected zone (HAZ) weldment components from archival piping specimens following a Screening Irradiation in the University of Buffalo Reactor (UBR) and following a Full-Term Irradiation in the High Flux Isotope Reactor (HFIR).

  17. Reactor Materials Program: Mechanical properties of irradiated Types 304 and 304L stainless steel weldment components

    SciTech Connect

    Sindelar, R.L.; Caskey, G.R. Jr.

    1991-12-01

    The vessels (reactor tanks) of the Savannah River Site nuclear production reactors constructed in the 1950`s are comprised of Type 304 stainless steel with Type 308 stainless steel weld filler. Irradiation exposure to the reactor tank sidewalls through reactor operation has caused a change in the mechanical properties of these materials. A database of as-irradiated mechanical properties for site-specific materials and irradiation conditions has been produced for reactor tank structural analyses and to quantify the effects of radiation-induced materials degradation for evaluating reactor service life. The data has been collected from the SRL Reactor Materials Program (RMP) irradiations and testing of archival stainless steel weldment components and from previous SRL programs to measure properties of irradiated reactor Thermal Shield weldments and reactor tank (R-tank) sidewall material. Irradiation programs of the RMP are designed to quantify mechanical properties at tank operating temperatures following irradiation to present and future tank wall maximum exposure conditions. The exposure conditions are characterized in terms of fast neutron fluence (E{sub n} > 0.1 MeV) and displacements per atom (dpa){sup 3}. Tensile properties, Charpy-V notch toughness, and elastic-plastic fracture toughness were measured for base, weld, and weld heat-affected zone (HAZ) weldment components from archival piping specimens following a Screening Irradiation in the University of Buffalo Reactor (UBR) and following a Full-Term Irradiation in the High Flux Isotope Reactor (HFIR).

  18. Symbolic derivation of material property matrices in finite element analysis

    NASA Technical Reports Server (NTRS)

    Tan, H. Q.

    1988-01-01

    The principles and operation of MMAX, a symbolic-computation program which automates the process of generating property matrices for structural materials, are briefly described and illustrated with sample analyses of a rubberlike material and an elastoplastic material. MMAX is written in LISP under the symbolic finite-element generator FINGER and the general symbolic manipulator MACSYMA; it first derives the formulas required by mathematical manipulation, and then translates the formulas into FORTRAN code, adapted to the particular type of machine to be used for the numerical calculations. This approach is shown to combine efficiently the advantages of symbolic and numerical computation for engineering applications.

  19. MICROSTRUCTURAL FEATURES AFFECTING PROPERTIES AND AGING OF TRITIUM-EXPOSED AUSTENTIC STAINLESS STEEL

    SciTech Connect

    Subramanian, K; Michael Morgan, M

    2004-01-10

    A project to implement a life-cycle engineering approach to tritium reservoirs has been initiated through the DOE - Technology Investment Projects. The first task in the project was to develop a comprehensive list of microstructural features that impact the aging performance of the tritium reservoirs. Each of the participating sites (SRNL, SNL, LANL, KCP) independently developed a list of features deemed integral to tritium reservoir performance based upon operational and design experience. An integrated list of features was ultimately developed by the project team that could be included in the modeling process. The features of interest were chosen based upon their impact on the following key factors in controlling crack growth: (1) the H/He solubility or diffusivity within the materials, (2) the stress/strain state at the crack tip, (3) material threshold for crack extension, and (4) microstructure based fracture distance, commonly estimated by grain size for intergranular fracture. Wherever possible, key references were identified to substantiate the effects on the tritium embrittlement phenomenon of the various microstructural features. Each of these features was chosen based upon their impact to the cracking phenomenon of interest. The features chosen were typically associated with orientation, morphology, and distribution of phases and inclusions, grain and grain boundary characteristics, and initial mechanical properties. Phase and inclusion content and distribution were determined to play a key role in the cracking phenomenon. The presence of {delta}-ferrite in the weld and strain-induced martensite in the primarily austenitic matrix are known to facilitate hydrogen diffusion and the interfaces have been observed as a hydrogen assisted fracture path. The morphology, size, and distribution of inclusions and precipitates, particularly on the grain boundaries, influence cracking since they trap hydrogen and facilitate intergranular fracture. Compositional

  20. Food material properties and early hominin processing techniques.

    PubMed

    Zink, Katherine D; Lieberman, Daniel E; Lucas, Peter W

    2014-12-01

    Although early Homo is hypothesized to have used tools more than australopiths to process foods prior to consumption, it is unknown how much the food processing techniques they used altered the material properties of foods, and therefore the masticatory forces they generated, and how well they were able to comminute foods. This study presents experimental data on changes to food material properties caused by mechanical tenderization (pounding with a stone tool) and cooking (dry roasting) of two foods likely to have been important components of the hominin diet: meat and tubers. Mechanical tenderization significantly decreased tuber toughness by 42%, but had no effect on meat toughness. Roasting significantly decreased several material properties of tubers correlated with masticatory effort including toughness (49%), fracture stress (28%) and elastic modulus (45%), but increased the toughness (77%), fracture stress (50%-222%), and elastic modulus of muscle fibers in meat (308%). Despite increasing many material properties of meat associated with higher masticatory forces, roasting also decreased measured energy loss by 28%, which likely makes it easier to chew. These results suggest that the use of food processing techniques by early Homo probably differed for meat and tubers, but together would have reduced masticatory effort, helping to relax selection to maintain large, robust faces and large, thickly enameled teeth. PMID:25439707

  1. Learning to Apply Models of Materials While Explaining Their Properties

    ERIC Educational Resources Information Center

    Karpin, Tiia; Juuti, Kalle; Lavonen, Jari

    2014-01-01

    Background: Applying structural models is important to chemistry education at the upper secondary level, but it is considered one of the most difficult topics to learn. Purpose: This study analyses to what extent in designed lessons students learned to apply structural models in explaining the properties and behaviours of various materials.…

  2. Moisture effect on mechanical properties of polymeric composite materials

    NASA Astrophysics Data System (ADS)

    Airale, A. G.; Carello, M.; Ferraris, A.; Sisca, L.

    2016-05-01

    The influence of moisture on the mechanical properties of fibre-reinforced polymer matrix composites (PMCs) was investigated. Four materials had been take into account considering: both 2×2-Twill woven carbon fibre or glass fibre, thermosetting matrix (Epoxy Resin) or thermoplastic matrix (Polyphenylene Sulfide). The specimens were submitted for 1800 hours to a hygrothermic test to evaluate moisture absorption on the basis of the Fick's law and finally tested to verify the mechanical properties (ultimate tensile strength). The results showed that the absorbed moisture decreases those properties of composites which were dominated by the matrix or the interface, while was not detectable the influence of water on the considered fibre. An important result is that the diffusion coefficient is highest for glass/PPS and lowest for carbon/epoxy composite material. The results give useful suggestions for the design of vehicle components that are exposed to environmental conditions (rain, snow and humidity).

  3. Comparative study of the physical properties of core materials.

    PubMed

    Saygili, Gülbin; Mahmali, Sevil M

    2002-08-01

    This study was undertaken to measure physical properties of materials used for direct core buildups, including high-copper amalgam, visible light-cured resin composite, autocured titanium-containing composite, polyacid-modified composite, resin-modified glass-ionomer, and silver cermet cement. Compressive strength, diametral tensile strength, and flexural strength of six core materials of various material classes were measured for each material as a function of time up to 3 months at different storage conditions, using a standard specification test designed for the materials. Three different storage conditions (dry, humid, wet) at 37 degrees C were chosen. Materials were manipulated according to manufacturers' instructions for use as cores. Mean compressive, diametral tensile, and flexural strengths with associated standard deviations were calculated for each material. Multiple comparison and Newman-Keuls tests discerned many differences among materials. All materials were found to meet the minimum specification requirements, except in terms of flexural strength for amalgam after 1 hour and the silver cermet at all time intervals. PMID:12212682

  4. Defect-related luminescent materials: synthesis, emission properties and applications.

    PubMed

    Zhang, Cuimiao; Lin, Jun

    2012-12-01

    Luminescent materials have found a wide variety of applications, including information displays, lighting, X-ray intensification and scintillation, and so on. Therefore, much effort has been devoted to exploring novel luminescent materials so far. In the past decade, defect-related luminescent materials have inspired intensive research efforts in their own right. This kind of luminescent material can be basically classified into silica-based materials, phosphate systems, metal oxides, BCNO phosphors, and carbon-based materials. These materials combine several favourable attributes of traditional commercially available phosphors, which are stable, efficient, and less toxic, being free of the burdens of intrinsic toxicity or elemental scarcity and the need for stringent, intricate, tedious, costly, or inefficient preparation steps. Defect-related luminescent materials can be produced inexpensively and on a large scale by many approaches, such as sol-gel process, hydro(solvo)thermal reaction, hydrolysis methods, and electrochemical methods. This review article highlights the recent advances in the chemical synthesis and luminescent properties of the defect-related materials, together with their control and tuning, and emission mechanisms (solid state physics). We also speculate on their future and discuss potential developments for their applications in lighting and biomedical fields. PMID:23019577

  5. Structure-property relationships in silica-siloxane nanocomposite materials

    SciTech Connect

    Ulibarri, T.A.; Derzon, D.K.; Wang, L.C.

    1997-03-01

    The simultaneous formation of a filler phase and a polymer matrix via in situ sol-gel techniques provides silica-siloxane nanocomposite materials of high strength. This study concentrates on the effects of temperature and relative humidity on a trimodal polymer system in an attempt to accelerate the reaction as well as evaluate subtle process- structure-property relations. It was found that successful process acceleration is only viable for high humidity systems when using the tin(IV) catalyst dibutyltin dilaurate. Processes involving low humidity were found to be very temperature and time dependent. Bimodal systems were investigated and demonstrated that the presence of a short-chain component led to enhanced material strength. This part of the study also revealed a link between the particle size and population density and the optimization of material properties.

  6. Material properties study of the MJ-2 grout

    SciTech Connect

    Larson, D.B.

    1988-08-01

    Material properties experimental tests using the high pressure testing equipment at LLNL have been performed on the grout used in the Mini Jade-2 event (MJ-2) as part of a high pressure equation of state study sponsored by the Defense Nuclear Agency in support of the Misty Echo experiment at the Nevada Test Site. The material properties tests performed at LLNL and included in this report are (1) pressure-volume compression studies to 3.6 GPa, (2) pressure-volume compression and unloading studies to /approximately/1 GPa, and (3) material strength versus confining pressure to /approximately/1 GPa. These data are compared with dynamic results and with other static data using this grout. 4 refs., 5 figs., 4 tabs.

  7. Residual stresses calculation in autofrettage using variable material properties method

    SciTech Connect

    Jahed, H.; Dubey, R.N.

    1996-12-01

    Autofrettaged cylinders are used for variety of applications in chemical and nuclear industries where large internal pressures have to be withstood. Autofrettage is in the process by which beneficial residual stresses are introduced into thick-walled tubes by initially subjected the tube to high internal pressure which causes inelastic deformation. Here, the variable material properties method is employed to obtain elastic-plastic analysis of an autofrettaged tube. This method develops inelastic solution from the elastic solution by treating the material properties as field variables. The distribution of these parameters are obtained in an iterative manner as a part of the solution. An energy based scheme is used to update these variables. The residual stress field of autofrettaged tubes based on the actual material curve and isotropic and kinematic hardening models are obtained. The results are shown to be in good agreement with the published experimental and finite element results.

  8. Computing estimates of material properties from transmission eigenvalues

    NASA Astrophysics Data System (ADS)

    Giorgi, Giovanni; Haddar, Houssem

    2012-05-01

    This work is motivated by inverse scattering problems, those problems where one is interested in reconstructing the shape and the material properties of an inclusion from electromagnetic farfield measurements. More precisely, we are interested in complementing the so-called sampling methods by providing an estimate of the material properties of the sought inclusion. We use for this purpose a measure of the first transmission eigenvalue. Our method is then based on computing the desired estimate by reformulating the so-called interior transmission eigenvalue problem as an eigenvalue problem for the material coefficients. We will restrict ourselves to the two-dimensional setting of the problem and treat the cases of both transverse electric and transverse magnetic polarizations. We present a number of numerical experiments that validate our methodology for homogeneous and inhomogeneous inclusions and backgrounds. We also treat the case of a background with absorption and the case of scatterers with multiple connected components of different refractive indices.

  9. Thermoelastic analysis of solar cell arrays and their material properties

    NASA Technical Reports Server (NTRS)

    Salama, M. A.; Rowe, W. M.; Yasui, R. K.

    1973-01-01

    A thermoelastic stress analysis procedure is reported for predicting the thermally induced stresses and failures in silicon solar cell arrays. A prerequisite for the analysis is the characterization of the temperature-dependent thermal and mechanical properties of the solar cell materials. Extensive material property testing was carried out in the temperature range -200 to +200 C for the filter glass, P- and N-type silicon, interconnector metals, solder, and several candidate silicone rubber adhesives. The analysis procedure is applied to several solar cell array design configurations. Results of the analysis indicate the optimum design configuration, with respect to compatible materials, effect of the solder coating, and effect of the interconnector geometry. Good agreement was found between results of the analysis and the test program.

  10. Thermoelastic analysis of solar cell arrays and their material properties

    NASA Technical Reports Server (NTRS)

    Salama, M. A.; Rowe, W. M.; Yasui, R. K.

    1974-01-01

    Description of a thermoelastic stress analysis procedure for predicting the thermally induced stresses and failures in silicon solar cell arrays. A prerequisite for the analysis is the characterization of the temperature-dependent thermal and mechanical properties of the solar cell materials. Extensive material property testing was carried out in the temperature range from -200 to +200 C for the filter glass, P- and N-type silicon, interconnector metals, solder, and several candidate silicone rubber adhesives. The analysis procedure is applied to several solar cell array design configurations, which were tested in the Space Molecular Sink. Results of the analysis indicate the optimum design configuration with respect to materials and geometry, effect of the solder coating, and effect of the interconnector geometry.

  11. Millimeter wave and terahertz dielectric properties of biological materials

    NASA Astrophysics Data System (ADS)

    Khan, Usman Ansar

    Broadband dielectric properties of materials can be employed to identify, detect, and characterize materials through their unique spectral signatures. In this study, millimeter wave, submillimeter wave, and terahertz dielectric properties of biological substances inclusive of liquids, solids, and powders were obtained using Dispersive Fourier Transform Spectroscopy (DFTS). Two broadband polarizing interferometers were constructed to test materials from 60 GHz to 1.2 THz. This is an extremely difficult portion of the frequency spectrum to obtain a material's dielectric properties since neither optical nor microwave-based techniques provide accurate data. The dielectric characteristics of liquids such as cyclohexane, chlorobenzene, benzene, ethanol, methanol, 1,4 dioxane, and 10% formalin were obtained using the liquid interferometer. Subsequently the solid interferometer was utilized to determine the dielectric properties of human breast tissues, which are fixed and preserved in 10% formalin. This joint collaboration with the Tufts New England Medical Center demonstrated a significant difference between the dielectric response of tumorous and non-tumorous breast tissues across the spectrum. Powders such as anthrax, flour, talc, corn starch, dry milk, and baking soda have been involved in a number of security threats and false alarms around the globe in the last decade. To be able to differentiate hoax attacks and serious security threats, the dielectric properties of common household powders were also examined using the solid interferometer to identify the powders' unique resonance peaks. A new sample preparation kit was designed to test the powder specimens. It was anticipated that millimeter wave and terahertz dielectric characterization will enable one to clearly distinguish one powder from the other; however most of the powders had relatively close dielectric responses and only Talc had a resonance signature recorded at 1.135 THz. Furthermore, due to

  12. Development and Analysis of Synthetic Composite Materials Emulating Patient AAA Wall Material Properties

    NASA Astrophysics Data System (ADS)

    Margossian, Christa M.

    Abdominal Aortic Aneurysm (AAA) rupture accounts for 14,000 deaths a year in the United States. Since the number of ruptures has not decreased significantly in recent years despite improvements in imaging and surgical procedures, there is a need for an accurate, noninvasive technique capable of establishing rupture risk for specific patients and discriminating lesions at high risk. In this project, synthetic composite materials replicating patient-specific wall stiffness and strength were developed and their material properties evaluated. Composites utilizing various fibers were developed to give a range of stiffness from 1825.75 kPa up through 8187.64 kPa with one base material, Sylgard 170. A range of strength from 631.12 kPa to 1083 kPa with the same base material was also found. By evaluating various base materials and various reinforcing fibers, a catalogue of stiffnesses and strengths was started to allow for adaptation to specific patient properties. Three specific patient properties were well-matched with two composites fabricated: silk thread-reinforced Sylgard 170 and silk thread-reinforced Dragon Skin 20. The composites showed similar stiffnesses to the specific patients while reaching target stresses at particular strains. Not all patients were matched with composites as of yet, but recommendations for future matches are able to be determined. These composites will allow for the future evaluation of flow-induced wall stresses in models replicating patient material properties and geometries.

  13. Material Properties Analysis of Structural Members in Pumpkin Balloons

    NASA Technical Reports Server (NTRS)

    Sterling, W. J.

    2003-01-01

    The efficient design, service-life qualification, and reliability predictions for lightweight aerospace structures require careful mechanical properties analysis of candidate structural materials. The demand for high-quality laboratory data is particularly acute when the candidate material or the structural design has little history. The pumpkin-shaped super-pressure balloon presents both challenges. Its design utilizes load members (tendons) extending from apex to base around the gas envelope to achieve a lightweight structure. The candidate tendon material is highly weight-efficient braided HM cord. Previous mechanical properties studies of Zylon have focused on fiber and yarn, and industrial use of the material in tensile applications is limited. For high-performance polymers, a carefully plamed and executed properties analysis scheme is required to ensure the data are relevant to the desired application. Because no directly-applicable testing standard was available, a protocol was developed based on guidelines fiom professional and industry organizations. Due to the liquid-crystalline nature of the polymer, the cord is very stiff, creeps very little, and does not yield. Therefore, the key material property for this application is the breaking strength. The pretension load and gauge length were found to have negligible effect on the measured breaking strength over the ranges investigated. Strain rate was found to have no effect on breaking strength, within the range of rates suggested by the standards organizations. However, at the lower rate more similar to ULDB operations, the strength was reduced. The breaking strength increased when the experiment temperature was decreased from ambient to 183K which is the lowest temperature ULDB is expected to experience. The measured strength under all test conditions was well below that resulting from direct scale-up of fiber strength based on the manufacturers data. This expected result is due to the effects of the

  14. Material Property Measurement in Hostile Environments using Laser Acoustics

    SciTech Connect

    Ken L. Telschow

    2004-08-01

    Acoustic methods are well known and have been used to measure various intrinsic material properties, such as, elastic coefficients, density, crystal axis orientation, microstructural texture, and residual stress. Extrinsic properties, such as, dimensions, motion variables or temperature are also readily determined from acoustic methods. Laser acoustics, employing optical generation and detection of elastic waves, has a unique advantage over other acoustic methods—it is noncontacting, uses the sample surface itself for transduction, requires no couplant or invasive sample surface preparation and can be utilized in any hostile environment allowing optical access to the sample surface. In addition, optical generation and detection probe beams can be focused to the micron scale and/or shaped to alter the transduction process with a degree of control not possible using contact transduction methods. Laser methods are amenable to both continuous wave and pulse-echo measurements and have been used from Hz to 100’s of GHz (time scales from sec to psec) and with amplitudes sufficient to fracture materials. This paper shall review recent applications of laser acoustic methods to determining material properties in hostile environments that preclude the use of contacting transduction techniques. Example environments include high temperature (>1000C) sintering and molten metal processing, thin film deposition by plasma techniques, materials moving at high velocity during the fabrication process and nuclear high radiation regions. Recent technological advances in solid-state lasers and telecommunications have greatly aided the development and implementation of laser acoustic methods, particularly at ultra high frequencies. Consequently, laser acoustic material property measurements exhibit high precision and reproducibility today. In addition, optical techniques provide methods of imaging acoustic motion that is both quantitative and rapid. Possible future directions for

  15. Physico-mechanical properties determination using microscale homotopic measurements: application to sound and caries-affected primary tooth dentin.

    PubMed

    Marangos, Orestes; Misra, Anil; Spencer, Paulette; Bohaty, Brenda; Katz, J Lawrence

    2009-05-01

    Microscale elastic moduli, composition and density have rarely been determined at the same location for biological materials. In this paper, we have performed homotopic measurements to determine the physico-mechanical properties of a second primary molar specimen exhibiting sound and caries-affected regions. A microscale acoustic impedance map of a section through this sample was acquired using scanning acoustic microscopy (SAM). Scanning electron microscopy was then used to obtain mineral mass fraction of the same section using backscattered images. Careful calibration of each method was performed to reduce system effects and obtain accurate data. Resorption, demineralization and hypermineralization mechanisms were considered in order to derive relationships between measured mineral mass fraction and material mass density. As a result, microscale mass density was determined at the same lateral resolution and location as the SAM data. The mass density and the acoustic impedance were combined to find the microscale elastic modulus and study the relationship between microscale composition and mechanical properties. PMID:19059013

  16. Characterization of the electromechanical properties of EAP materials

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph; Sherrita, Stewart; Bhattachary, Kaushik; Lih, Shyh-Shiuh

    2001-01-01

    Electroactive polymers (EAP) are an emerging class of actuation materials. Their large electrically induced strains (longitudinal or bending), low density, mechanical flexibility, and ease of processing offer advantages over traditional electroactive materials. However, before the capability of these materials can be exploited, their electrical and mechanical behavior must be properly quantified. Two general types of EAP can be identified. The first type is ionic EAP, which requires relatively low voltages (<10V) to achieve large bending deflections. This class usually needs to be hydrated and electrochemical reactions may occur. The second type is Electronic-EAP and it involves electrostrictive and/or Maxwell stresses. This type of materials requires large electric fields (>100MV/m) to achieve longitudinal deformations at the range from 4 - 360%. Some of the difficulties in characterizing EAP include: nonlinear properties, large compliance (large mismatch with metal electrodes), nonhomogeneity resulting from processing, etc. To support the need for reliable data, the authors are developing characterization techniques to quantify the electroactive responses and material properties of EAP materials. The emphasis of the current study is on addressing electromechanical issues related to the ion-exchange type EAP also known as IPMC. The analysis, experiments and test results are discussed in this paper.

  17. Material properties effects on the detonation spreading and propagation of diaminoazoxyfurazan (DAAF)

    SciTech Connect

    Francois, Elizabeth Green; Morris, John S; Novak, Alan M; Kennedy, James E

    2010-01-01

    Recent dynamic testing of Diaminoazoxyfurazan (DAAF) has focused on understanding the material properties affecting the detonation propagation, spreading, behavior and symmetry. Small scale gap testing and wedge testing focus on the sensitivity to shock with the gap test including the effects of particle size and density. Floret testing investigates the detonation spreading as it is affected by particle size, density, and binder content. The polyrho testing illustrates the effects of density and binder content on the detonation velocity. Finally the detonation spreading effect can be most dramatically seen in the Mushroom and Onionskin tests where the variations due to density gradients, pressing methods and geometry can be seen on the wave breakout behavior.

  18. CB1 antagonism: interference with affective properties of acute naloxone-precipitated morphine withdrawal in rats

    PubMed Central

    Wills, Kiri L.; Vemuri, Kiran; Kalmar, Alana; Lee, Alan; Limebeer, Cheryl L.; Makriyannis, Alexandros

    2014-01-01

    Rationale Modulation of the endocannabinoid system has been found to interfere with opiate withdrawal. The potential of activation and blockade of the endocannabinoid system to prevent the aversive-affective state of naloxone-precipitated morphine withdrawal (MWD) was investigated in a one-trial conditioned place aversion (CPA) paradigm. Objective CPA provides a sensitive measure of the motivational effects of acute MWD. The potential of the fatty acid amide hydrolase (FAAH) inhibitors, URB597 and PF-3845, the CB1 antagonist/inverse agonist, AM251, and the neutral CB1 antagonists, AM4113 and AM6527 (oral), to interfere with establishment of a MWD-induced CPA was investigated. As well, the potential of AM251 and AM4113 to interfere with reinstatement of a previously established MWD-induced CPA was investigated. Materials and methods Using a one-trial place conditioning paradigm, rats were administered naloxone (1 mg/kg, subcutaneous (sc)) 24 h after receiving a high dose of morphine (20 mg/kg, sc) and were placed on the conditioning floor. To determine the effect of each pretreatment drug on the establishment of the MWD-induced CPA, URB597 (0.3 mg/kg, intraperitoneally (ip)), PF-3845 (10 mg/kg, ip), AM251 (1 or 2.5 mg/kg, ip), AM4113 (1 or 2.5 mg/kg, ip), and AM6527 (5 mg/kg, oral) were administered prior to conditioning. Results AM251 (2.5, but not 1 mg/k), AM4113, and AM6527, but not URB597 or PF-3845, interfered with the establishment of the MWD-induced CPA. AM251 and AM4113 did not prevent reinstatement of the CPA. Conclusions Neutral antagonism of the CB1 receptor reduces the aversive affective properties of morphine withdrawal. PMID:24770676

  19. AB INITIO SIMULATIONS FOR MATERIAL PROPERTIES ALONG THE JUPITER ADIABAT

    SciTech Connect

    French, Martin; Becker, Andreas; Lorenzen, Winfried; Nettelmann, Nadine; Bethkenhagen, Mandy; Redmer, Ronald; Wicht, Johannes

    2012-09-15

    We determine basic thermodynamic and transport properties of hydrogen-helium-water mixtures for the extreme conditions along Jupiter's adiabat via ab initio simulations, which are compiled in an accurate and consistent data set. In particular, we calculate the electrical and thermal conductivity, the shear and longitudinal viscosity, and diffusion coefficients of the nuclei. We present results for associated quantities like the magnetic and thermal diffusivity and the kinematic shear viscosity along an adiabat that is taken from a state-of-the-art interior structure model. Furthermore, the heat capacities, the thermal expansion coefficient, the isothermal compressibility, the Grueneisen parameter, and the speed of sound are calculated. We find that the onset of dissociation and ionization of hydrogen at about 0.9 Jupiter radii marks a region where the material properties change drastically. In the deep interior, where the electrons are degenerate, many of the material properties remain relatively constant. Our ab initio data will serve as a robust foundation for applications that require accurate knowledge of the material properties in Jupiter's interior, e.g., models for the dynamo generation.

  20. Physicochemical properties and structural changes in vegetative tissues as affected by a direct current electrical field.

    PubMed

    Zvitov, R; Nussinovitch, A

    2001-01-01

    Cylindrical pieces of potato, sweet potato, kohlrabi, radish, and pear were interposed between a pair of electrodes, and a direct current was applied. A special custom-made apparatus enabled the use of differently shaped electrodes. The electrical field was applied for 1 min at 40 V/cm and caused a reduction in specimen weight by a minimal value of 2.7% of initial weight in sweet potato to a maximum 38.4% in pear. The affected area of the tissue resembled the shape of the electrode. Pores were produced in the tissue (from the anode side), possibly promoting slow release of minerals and other cell components from the contracted specimens. From the cathode side, cell "sealing" could be observed. Weight loss was dependent on the mechanical properties of the nontreated vegetative tissue specimens. After confirmation that all samples pass through induced electrical shrinkage, further work, executed only on potato, demonstrated that after electrical treatment the samples were less brown (higher L values). In addition, a dependence of weight loss on current intensity, electrode diameter, and surface ratio between the electrode and specimen was shown. The reduction in weight loss could be useful for initial drying of vegetative materials. Indirect proof of a decrease in enzyme activity as a result of electrical field application could be beneficial in replacing traditional methods for browning prevention. PMID:11735447

  1. Mechanical properties of materials with nanometer scale microstructures

    SciTech Connect

    Nix, W.D.

    1991-07-01

    For the past two years we have been engaged in a program of research on the mechanical properties of a variety of new materials with nanometer scale microstructures. These materials have been developed recently using vapor phase synthesis techniques and are available in the form of compositionally-modulated (multilayered) thin film materials and ultrafine-grained (nanocrystalline) solids. They have interesting microstructures and mechanical properties that may lead to new applications for these materials. In this report we give a brief summary of some of the results we have obtained to date in the course of this research. Other, more detailed, descriptions of some of this work can be found in the papers that we have published. These are listed at the end of this report along with a listing of the oral presentations we have given. We report briefly on our studies of the elastic properties of metallic multilayered thin films. Using indentation and microbeam deflection techniques, we have found that Au/Ni multilayers do not show supermodulus effects, contrary to some previous reports based on bulge test results. However, we have discovered large and significant substrate interaction stresses in these films which depend systematically on the composition modulation wavelength. We believe that these residual stresses may have led to bulge testing errors which in turn led to erroneous reports of supermodulus effects.

  2. Role of defects in frictional properties of 2-D materials

    NASA Astrophysics Data System (ADS)

    Kavalur, Aditya; Kim, Woo Kyun

    Graphene and other 2-D materials have provided a promising prospect to improve the tribological properties of small length scale devices such as MEMS/NEMS due to their low friction coefficient and excellent wear resistance. Several recent research efforts have been devoted to unveiling the physical origin of the superior tribological properties of these 2-D materials from both experimental and theoretical standpoints, however, many of them still remain far from clearly understood. Recently, it was shown that lamellar materials do not conform to the predictions of the Prandtl-Tomlinson model due to additional friction mechanisms of delamination and visco-elastic ploughing. These mechanisms are critical as they explain the low and negative coefficients of friction observed in recent AFM experiments. However, thus far, most simulation and theoretical studies about these novel friction mechanisms have focused on only pristine graphene whereas real graphene sheets prepared by CVD and other conventional techniques possess various forms of defects such as vacancies and non-hexagonal rings. In this study we examine the role of these defects in frictional properties of 2-D materials in relation to delamination and visco-elastic ploughing.

  3. Temporal properties of material categorization and material rating: visual vs non-visual material features.

    PubMed

    Nagai, Takehiro; Matsushima, Toshiki; Koida, Kowa; Tani, Yusuke; Kitazaki, Michiteru; Nakauchi, Shigeki

    2015-10-01

    Humans can visually recognize material categories of objects, such as glass, stone, and plastic, easily. However, little is known about the kinds of surface quality features that contribute to such material class recognition. In this paper, we examine the relationship between perceptual surface features and material category discrimination performance for pictures of materials, focusing on temporal aspects, including reaction time and effects of stimulus duration. The stimuli were pictures of objects with an identical shape but made of different materials that could be categorized into seven classes (glass, plastic, metal, stone, wood, leather, and fabric). In a pre-experiment, observers rated the pictures on nine surface features, including visual (e.g., glossiness and transparency) and non-visual features (e.g., heaviness and warmness), on a 7-point scale. In the main experiments, observers judged whether two simultaneously presented pictures were classified as the same or different material category. Reaction times and effects of stimulus duration were measured. The results showed that visual feature ratings were correlated with material discrimination performance for short reaction times or short stimulus durations, while non-visual feature ratings were correlated only with performance for long reaction times or long stimulus durations. These results suggest that the mechanisms underlying visual and non-visual feature processing may differ in terms of processing time, although the cause is unclear. Visual surface features may mainly contribute to material recognition in daily life, while non-visual features may contribute only weakly, if at all. PMID:25536464

  4. Rectangular waveguide material characterization: anisotropic property extraction and measurement validation

    NASA Astrophysics Data System (ADS)

    Crowgey, Benjamin Reid

    for characterization of a sample filling the cross-section of a waveguide. Due to the rectangular nature of the waveguide, typically three different samples are manufactured from the same material in order to characterize the six complex material parameters. The second technique for measuring the electromagnetic properties of a biaxially anisotropic material sample uses a reduced-aperture waveguide sample holder designed to accommodate a cubical sample. All the tensor material parameters can then be determined by measuring the reflection and transmission coefficients of a single sample placed into several orientations. The parameters are obtained using a root-searching algorithm by comparing theoretically computed and measured reflection and transmission coefficients. The theoretical coefficients are determined using a mode matching technique. The first technique for characterizing the electromagnetic properties of gyromagnetic materials considers requires filling the cross-section of a waveguide. The material parameters are extracted from the measured reflection and transmission coefficients. Since the cross-sectional dimensions of waveguides become prohibitively large at low frequencies, and it is at these frequencies that the gyromagnetic properties are most pronounced, sufficiently large samples may not be available. Therefore, the second technique uses a reduced-aperture sample holder that does not require the sample to fill the entire cross section of the guide. The theoretical reflection and transmission coefficients for both methods are determined using a mode matching technique. A nonlinear least squares method is employed to extract the gyromagnetic material parameters. Finally, this dissertation introduces a waveguide standard that acts as a surrogate material with both electric and magnetic properties and is useful for verifying systems designed to characterize engineered materials using the NRW technique. A genetic algorithm is used to optimize the all

  5. Properties of a glass-ionomer/resin-composite hybrid material.

    PubMed

    Mathis, R S; Ferracane, J L

    1989-09-01

    A small percentage of the liquid resin used in commercial dental composites was added to the liquid used in a commercial glass-ionomer restorative in order to produce a fluoride-containing hybrid restorative-type material that would adhere to dentin while being stronger, less brittle, and less sensitive to desiccation in the oral cavity than glass ionomer. Compressive strength, yield strength, elastic modulus, fracture toughness, and tensile strength were analyzed for this hybrid, light-cured material. In addition, the solubility in water, adhesion to dentin, and surface roughness were also examined in vitro. The results suggest that the early (one-hour) mechanical properties of the hybrid material exceed those of glass ionomer. In addition, the brittleness and solubility of the material are less than those of commercial glass ionomer, while adhesion to dentin is unaffected. Most importantly, surface crazing, a documented problem with some glass ionomers when they become desiccated, is alleviated with this hybrid formulation. PMID:2638281

  6. Nuclear power plant containment metallic pressure boundary materials and plans for collecting and presenting their properties

    SciTech Connect

    Oland, C.B.

    1995-04-01

    A program is being conducted at the Oak Ridge National Laboratory (ORNL to assist the Nuclear Regulatory Commission (NRC)) in their assessment of the effects of degradation (primarily corrosion) on the structural capacity and leaktight integrity of metal containments and steel liners of reinforced concrete structures in nuclear power plants. One of the program objectives is to characterize and quantify manifestations of corrosion on the properties of steels used to construct containment pressure boundary components. This report describes a plan for use in collecting and presenting data and information on ferrous alloys permitted for use in construction of pressure retaining components in concrete and metal containments. Discussions about various degradation mechanisms that could potentially affect the mechanical properties of these materials are also included. Conclusions and recommendations presented in this report will be used to guide the collection of data and information that will be used to prepare a material properties data base for containment steels.

  7. Organic/inorganic nanocomposite materials by electrospinning and their properties

    NASA Astrophysics Data System (ADS)

    Wang, Guan

    One-dimensional (1D) nanostructures, such as nanowires, nanobelts, nanofibers and nanotubes, have been the focus of intensive research due to their peculiar structures and resultant fascinating properties. However, the applications of 1D nanostructures have been hindered by the slow progress of the synthesis and characterization methods for these nanoscaled materials. Well controlled dimensionality, tailorable morphology and assembly, high phase purity and controllable crystallinity are major concerns when generating these nanostructures. In this work, a relatively simple technique---electrospinning---has been introduced for the preparation of 1D organic/inorganic nanocomposite materials. Materials under investigation include polymer/metal oxide (WO 3, MoO3) composite nanofibers and polymer/MWNT composite nanofibers. Notably, peculiar nanostructures, such as polycrystalline nanowires, nanoplatelets and nanobelts, can also be obtained after post-calcination processing on the nanocomposite materials. Spectroscopy techniques, such as XRD, SEM, TEM, AFM and Raman have been carried out to obtain structural and morphological information from the electrospun composite nanofibers. Meanwhile, some advanced characterization methods and measurements have been developed and designed to investigate the nanofibers from a basic science view point as to their properties. Specific designs of experiment include: synchrotron-based in situ XRD for phase transition monitoring; gas flow control bench for sensitivity measurement; three-point-bending by AFM for mechanical property measurement. In summary, the electrospinning technique provides a versatile method for synthesizing and assembling 1D nanocomposite structures. The electrospun composite nanofibers showed promising electrical and mechanical properties, which may find applications for gas sensors, reinforced fibrous materials and nano-electrical devices.

  8. Elastic therapeutic tape: do they have the same material properties?

    PubMed Central

    Boonkerd, Chuanpis; Limroongreungrat, Weerawat

    2016-01-01

    [Purpose] Elastic therapeutic tape has been widely used for rehabilitation and treatment of sports injuries. Tapes with different elastic properties serve different treatment purposes with inappropriate tension reducing tape effectiveness. Many tapes are available in the market, but studies on tape properties are limited. The aim of this study was to examine the material properties of elastic therapeutic tape. [Subjects and Methods] Brands of elastic therapeutic tape included KinesioTex®, ATex, Mueller, 3M, and ThaiTape. The Material Testing System Insight® 1 Electromechanical Testing Systems was used to apply a tensile force on elastic therapeutic tape. Ten specimens of each brand were tested. Stress, load, and Young’s modulus at 25%, 50%, 75%, 100%, and maximum point were collected. One-way analysis of variance with post hoc testing was used to analyze tape parameters. [Results] Maximum elongation and Young’s modulus at all percentages were significantly different between brands. There were no differences in maximum load and maximum stress. [Conclusion] Mechanical properties are different for commercial elastic therapeutic tapes. Physiotherapists and other clinicians should be aware of mechanical tape properties to correctly apply kinesio tape. PMID:27190472

  9. Elastic therapeutic tape: do they have the same material properties?

    PubMed

    Boonkerd, Chuanpis; Limroongreungrat, Weerawat

    2016-04-01

    [Purpose] Elastic therapeutic tape has been widely used for rehabilitation and treatment of sports injuries. Tapes with different elastic properties serve different treatment purposes with inappropriate tension reducing tape effectiveness. Many tapes are available in the market, but studies on tape properties are limited. The aim of this study was to examine the material properties of elastic therapeutic tape. [Subjects and Methods] Brands of elastic therapeutic tape included KinesioTex(®), ATex, Mueller, 3M, and ThaiTape. The Material Testing System Insight(®) 1 Electromechanical Testing Systems was used to apply a tensile force on elastic therapeutic tape. Ten specimens of each brand were tested. Stress, load, and Young's modulus at 25%, 50%, 75%, 100%, and maximum point were collected. One-way analysis of variance with post hoc testing was used to analyze tape parameters. [Results] Maximum elongation and Young's modulus at all percentages were significantly different between brands. There were no differences in maximum load and maximum stress. [Conclusion] Mechanical properties are different for commercial elastic therapeutic tapes. Physiotherapists and other clinicians should be aware of mechanical tape properties to correctly apply kinesio tape. PMID:27190472

  10. An overview of laminate materials with enhanced dielectric properties

    NASA Astrophysics Data System (ADS)

    Mumby, Stephen J.

    1989-03-01

    This report focuses on laminate materials (resins and reinforcements) having potential applications in the manufacture of multi-layer printed wiring boards (PWBs) that are required to efficiently transmit high-speed digital pulses. It is intended to be a primer and a reference for selection of candidate materials for such high-performance PWBs. Included are dielectric and physical properties, and where available chemical composition and/or structure, commercial availability, compatibility with typical PWB processing schemes and approximate relative cost. Recommendations are made as to the most viable candidate materials for this type of PWB application, based on a comparison of electrical and physical properties together with processing and cost considerations. The cyanate ester resin system appears promising. Such a resin may be reinforced with regular E-glass, or the more newly available S-glass, to produce a laminate useful for intermediate performance applications. For more demanding applications the E-glass will have to be replaced by a material of much lower relative permittivity. The expanded-PTFE reinforced laminates from W. L. Gore appear to be a good choice for these applications. The processing of the Gore materials can be expected to deviate from that used with FR-4 type materials, but is likely to be less problematic than laminates comprised of a fluorinated resin. Processing is a key obstacle to the implementation of any of the new materials herein. If implementation is to be successful, programs must be established to develop and optimize processing procedures. Cost will remain an important issue. However, the higher cost of the new materials may be justified in high-end products by the performance they deliver.

  11. Microstructural and Morphological Factors Affecting Uncertainty in Small Scale Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Maughan, Michael R.

    If materials are to be developed from the ground up, the process will be dependent upon accurate and well-defined models of material behavior. These models can be closed-form solutions developed from first principles, simulations, or empirically derived equations, among others. Material behavior at the mesoscale is in general well understood, having had several centuries of study. However, behavior at the micro or nanoscale still requires characterization. Understanding the collective influence of the microstructure on the bulk material, for example with models like the Hall-Petch relation, has advanced our ability to manipulate the material to our advantage. We now have the ability to study not only the structure of the material, but also the material behavior and properties at the nanoscale. Understanding this behavior is critical to developing a framework for interpreting and utilizing these properties in materials design. This research aims to improve the fundamental understanding of the mechanical performance of materials and the subsequent variation in measured properties. The literature reports widely varying material properties such as hardness, elastic modulus, and yield point when measured at the nanoscale. Proposed variation mechanisms in these properties include surface preparation, error in measurement, heterogeneous dislocation density and distribution, crystal orientation, surface oxide film fracture, and others. Among other things, this work shows that these sources of variation can be determined and quantified, and that this information can be utilized as a characterization and/or predictive tool. The main goals of this work are to 1) continue basic research on sources of variation in the nanoscale properties of materials, specifically hardness and modulus in crystalline and glassy solids, 2) study the abrupt transition from elastic to plastic material behavior known as pop-in and resolve the problem of pseudo-elastic behavior prior to plasticity

  12. Electrostatic levitation technology for thermophysical properties of molten materials

    NASA Technical Reports Server (NTRS)

    Rhim, Won-Kyu

    1993-01-01

    Measurements of thermophysical properties of undercooled liquids often require some kind of levitator which isolates samples from container walls. We introduce in this presentation a high temperature/high vacuum electrostatic levitator (HTHVESL) which promises some unique capabilities for the studies of thermophysical properties of molten materials. Although substantial progress has been made in the past several months, this technology is still in the development stage, therefore, in this presentation we only focus on the present state of the HTHVESL(1) and point out other capabilities which might be realized in the near future.

  13. Electron Correlation and Tranport Properties in Nuclear Fuel Materials

    NASA Astrophysics Data System (ADS)

    Yin, Quan; Haule, Kristjan; Kotliar, Gabriel; Savrasov, Sergey; Pickett, Warren

    2011-03-01

    Using first principle LDA+DMFT method, we conduct a systematic study on the correlated electronic structures and transport properties of select actinide carbides, nitrides, and oxides, many of which are nuclear fuel materials. Our results capture the metal--insulator Mott transition within the studied systems, and the appearance of the Zhang-Rice state in uranium dioxide. More importantly, by understanding the physics underlying their transport properties, we suggest ways to improve the efficiency of currently used fuels. This work is supported by the DOE Nuclear Energy University Program, contract No. 00088708.

  14. Statistically based material properties: A military handbook-17 perspective

    NASA Technical Reports Server (NTRS)

    Neal, Donald M.; Vangel, Mark G.

    1990-01-01

    The statistical procedures and their importance in obtaining composite material property values in designing structures for aircraft and military combat systems are described. The property value is such that the strength exceeds this value with a prescribed probability with 95 percent confidence in the assertion. The survival probabilities are the 99th percentile and 90th percentile for the A and B basis values respectively. The basis values for strain to failure measurements are defined in a similar manner. The B value is the primary concern.

  15. Spatial and temporal variability of soil hydraulic properties of topsoil affected by soil erosion

    NASA Astrophysics Data System (ADS)

    Nikodem, Antonin; Kodesova, Radka; Jaksik, Ondrej; Jirku, Veronika; Klement, Ales; Fer, Miroslav

    2014-05-01

    This study is focused on the comparison of soil hydraulic properties of topsoil that is affected by erosion processes. In order to include variable morphological and soil properties along the slope three sites - Brumovice, Vidim and Sedlčany were selected. Two transects (A, B) and five sampling sites along each one were chosen. Soil samples were taken in Brumovice after the tillage and sowing of winter wheat in October 2010 and after the wheat harvest in August 2011. At locality Vidim and Sedlčany samples were collected in May and August 2012. Soil hydraulic properties were studied in the laboratory on the undisturbed 100-cm3 soil samples placed in Tempe cells using the multi-step outflow test. Soil water retention data points were obtained by calculating water balance in the soil sample at each pressure head step of the experiment. The single-porosity model in HYDRUS-1D was applied to analyze the multi-step outflow and to obtain the parameters of soil hydraulic properties using the numerical inversion. The saturated hydraulic conductivities (Ks) and unsaturated hydraulic conductivities (Kw) for the pressure head of -2 cm of topsoil were also measured after the harvest using Guelph permeameter and Minidisk tensiometer, respectively. In general soil water retention curves measured before and after vegetation period apparently differed, which indicated soil material consolidation and soil-porous system rearrangement. Soil water retention curves obtained on the soil samples and hydraulic conductivities measured in the field reflected the position at the elevation transect and the effect of erosion/accumulation processes on soil structure and consequently on the soil hydraulic properties. The highest Ks values in Brumovice were obtained at the steepest parts of the elevation transects, that have been the most eroded. The Ks values at the bottom parts decreased due to the sedimentation of eroded soil particles. The change of the Kw values along transects didn't show

  16. Effective material properties of thermoelectric composites with elliptical fibers

    NASA Astrophysics Data System (ADS)

    Wang, Yi-Ze

    2015-06-01

    In the present work, the effective material properties of thermoelectric composites with elliptical fibers are studied. Explicit solutions are derived by the conformal mapping function and Mori-Tanaka method. Numerical simulations are performed to present the behaviors of normalized effective material constants. From the results, it can be observed that both the effective electric and thermal conductivities can be reduced by increasing the filling ratio and a/ b. Such influences can also be found for the effective thermoelectric figure of merit. But they are different from those on the effective Seebeck and Peltier coefficients.

  17. Advances in optical property measurements of spacecraft materials

    NASA Technical Reports Server (NTRS)

    Smith, Charles A.; Dever, Joyce A.; Jaworske, Donald A.

    1997-01-01

    Some of the instruments and experimental approaches, used for measuring the optical properties of thermal control systems, are presented. The instruments' use in studies concerning the effects of combined contaminants and space environment on these materials, and in the qualification of hardware for spacecraft, are described. Instruments for measuring the solar absorptance and infrared emittance offer improved speed, accuracy and data handling. A transient method for directly measuring material infrared emittance is described. It is shown that oxygen exposure before measuring the solar absorptance should be avoided.

  18. Mechanical Properties of Elastomeric Impression Materials: An In Vitro Comparison

    PubMed Central

    De Angelis, Francesco; Caputi, Sergio; D'Amario, Maurizio; D'Arcangelo, Camillo

    2015-01-01

    Purpose. Although new elastomeric impression materials have been introduced into the market, there are still insufficient data about their mechanical features. The tensile properties of 17 hydrophilic impression materials with different consistencies were compared. Materials and Methods. 12 vinylpolysiloxane, 2 polyether, and 3 hybrid vinylpolyether silicone-based impression materials were tested. For each material, 10 dumbbell-shaped specimens were fabricated (n = 10), according to the ISO 37:2005 specifications, and loaded in tension until failure. Mean values for tensile strength, yield strength, strain at break, and strain at yield point were calculated. Data were statistically analyzed using one-way ANOVA and Tukey's tests (α = 0.05). Results. Vinylpolysiloxanes consistently showed higher tensile strength values than polyethers. Heavy-body materials showed higher tensile strength than the light bodies from the same manufacturer. Among the light bodies, the highest yield strength was achieved by the hybrid vinylpolyether silicone (2.70 MPa). Polyethers showed the lowest tensile (1.44 MPa) and yield (0.94 MPa) strengths, regardless of the viscosity. Conclusion. The choice of an impression material should be based on the specific physical behavior of the elastomer. The light-body vinylpolyether silicone showed high tensile strength, yield strength, and adequate strain at yield/brake; those features might help to reduce tearing phenomena in the thin interproximal and crevicular areas. PMID:26693227

  19. A Statistics-Based Material Property Analysis to Support TPS Characterization

    NASA Technical Reports Server (NTRS)

    Copeland, Sean R.; Cozmuta, Ioana; Alonso, Juan J.

    2012-01-01

    Accurate characterization of entry capsule heat shield material properties is a critical component in modeling and simulating Thermal Protection System (TPS) response in a prescribed aerothermal environment. The thermal decomposition of the TPS material during the pyrolysis and charring processes is poorly characterized and typically results in large uncertainties in material properties as inputs for ablation models. These material property uncertainties contribute to large design margins on flight systems and cloud re- construction efforts for data collected during flight and ground testing, making revision to existing models for entry systems more challenging. The analysis presented in this work quantifies how material property uncertainties propagate through an ablation model and guides an experimental test regimen aimed at reducing these uncertainties and characterizing the dependencies between properties in the virgin and charred states for a Phenolic Impregnated Carbon Ablator (PICA) based TPS. A sensitivity analysis identifies how the high-fidelity model behaves in the expected flight environment, while a Monte Carlo based uncertainty propagation strategy is used to quantify the expected spread in the in-depth temperature response of the TPS. An examination of how perturbations to the input probability density functions affect output temperature statistics is accomplished using a Kriging response surface of the high-fidelity model. Simulations are based on capsule configuration and aerothermal environments expected during the Mars Science Laboratory (MSL) entry sequence. We identify and rank primary sources of uncertainty from material properties in a flight-relevant environment, show the dependence on spatial orientation and in-depth location on those uncertainty contributors, and quantify how sensitive the expected results are.

  20. Quantitative ultrasonic evaluation of mechanical properties of engineering materials

    NASA Technical Reports Server (NTRS)

    Vary, A.

    1978-01-01

    Current progress in the application of ultrasonic techniques to nondestructive measurement of mechanical strength properties of engineering materials is reviewed. Even where conventional NDE techniques have shown that a part is free of overt defects, advanced NDE techniques should be available to confirm the material properties assumed in the part's design. There are many instances where metallic, composite, or ceramic parts may be free of critical defects while still being susceptible to failure under design loads due to inadequate or degraded mechanical strength. This must be considered in any failure prevention scheme that relies on fracture analysis. This review will discuss the availability of ultrasonic methods that can be applied to actual parts to assess their potential susceptibility to failure under design conditions.

  1. Mechanical Properties of Materials with Nanometer Scale Microstructures

    SciTech Connect

    William D. Nix

    2004-10-31

    We have been engaged in research on the mechanical properties of materials with nanometer-scale microstructural dimensions. Our attention has been focused on studying the mechanical properties of thin films and interfaces and very small volumes of material. Because the dimensions of thin film samples are small (typically 1 mm in thickness, or less), specialized mechanical testing techniques based on nanoindentation, microbeam bending and dynamic vibration of micromachined structures have been developed and used. Here we report briefly on some of the results we have obtained over the past three years. We also give a summary of all of the dissertations, talks and publications completed on this grant during the past 15 years.

  2. New Technique for Evaluating Adhesion Properties between Soft Materials

    NASA Astrophysics Data System (ADS)

    Sato, Takaya; Goto, Motoaki; Nakano, Ken; Suzuki, Atsushi

    2005-11-01

    A new, simple apparatus for measuring the surface adhesion properties of soft materials was designed, where the adhesion force of a point contact between soft materials and the total energy required to separate the contact can be measured using the springs of phosphor-bronze thin plates with strain gauges. The adhesion between swollen hydrogels was studied here by this simple technique in air at room temperature. The gels used in the present preliminary experiments were poly(sodium acrylate) hydrogels physically cross-linked by aluminum ions. The adhesion force and the separation energy showed a power-law increase with separation velocity. The apparatus was applied to evaluate the adhesion properties of seven anti-inflammatory analgesic cataplasms on the market. It was found that the easiness to separate (rank of adhesion force and the separation energy) was consistent with the results of those obtained by organoleptic evaluations.

  3. PROPERTIES AND NANOSTRUCTURES OF MATERIALS PROCESSED BY SPD TECHNIQUES

    SciTech Connect

    Liao, Xiaoshan; Huang, J.; Zhu, Y. T.

    2001-01-01

    Metallic materials usually exhibit higher strength but lower ductility after being plastically deformed by conventional techniques such as rolling, drawing and extrusion. In contrast, nanostructured metals and alloys processed by severe plastic deformation (SPD) have demonstrated both high strength and high ductility. This extraordinary mechanical behavior is attributed to the unique nanostructures generated by SPD processing. It demonstrates the possibility of tailoring the microstructures of metals and alloys by SPD to obtain superior mechanical properties. The SPD-generated nanostructures have many features related to deformation, including high dislocation densities, and high- and low-angle grain boundaries in equilibrium or non-equilibrium states. This paper reviews the mechanical properties and the defect structures of SPD-processed nanostructured materials. Keywords: strength, ductility, nanostructures, SPD, non-equilibrium grain boundary

  4. Correlation of Local Structure and Electronic Properties of Glass Materials

    NASA Astrophysics Data System (ADS)

    Lordi, Vincenzo; Adelstein, Nicole

    2015-03-01

    Wide band gap glasses such as silica and its derivatives are typically considered insulators. However, electronic transport in glasses can be important for certain applications, such as when used as the host material for a scintillator radiation detector. Here we explore the relationship between local structure in glass materials and the corresponding electronic properties of carrier transport and charge trapping. We present a novel analysis that decomposes the distribution of localized band tail states in terms of specific local structural features in the glass. Comparison of the structure-related transport properties of different glass compositions is given, using silica and sodium silicate as prototypes. Prepared by LLNL under Contract DE-AC52-07NA27344.

  5. Effects of dielectric material properties on graphene transistor performance

    NASA Astrophysics Data System (ADS)

    Jang, Sung Kyu; Jeon, Jaeho; Jeon, Su Min; Song, Young Jae; Lee, Sungjoo

    2015-07-01

    Graphene has attracted attention due to its excellent electrical properties; however, the electrical performance of graphene devices, including device hysteresis, mobility, and conductivity, tends to be limited by the supporting dielectric layer properties. In this work, the impact of a dielectric material on a graphene transistor was investigated by fabricating graphene field effect transistors integrated with four different dielectric substrates (SiO2, Al2O3, Si3N4 and hexagonal boron nitride) and by comparing the transistor performances. Results revealed that the carrier transport characteristics of the graphene transistors, including the hysteresis, Dirac point shift, and mobility, were highly correlated with the hydrophobicity-induced charge trapping and surface optical phonon energies of the dielectric materials.

  6. Measurements of radiative material properties for astrophysical plasmas.

    SciTech Connect

    Bailey, James E.

    2010-10-01

    The new generation of z-pinch, laser, and XFEL facilities opens the possibility to produce astrophysically-relevant laboratory plasmas with energy densities beyond what was previously possible. Furthermore, macroscopic plasmas with uniform conditions can now be created, enabling more accurate determination of the material properties. This presentation will provide an overview of our research at the Z facility investigating stellar interior opacities, AGN warm-absorber photoionized plasmas, and white dwarf photospheres. Atomic physics in plasmas heavily influence these topics. Stellar opacities are an essential ingredient of stellar models and they affect what we know about the structure and evolution of stars. Opacity models have become highly sophisticated, but laboratory tests have not been done at the conditions existing inside stars. Our research is presently focused on measuring Fe at conditions relevant to the base of the solar convection zone, where the electron temperature and density are believed to be 190 eV and 9 x 10{sup 22} e/cc, respectively. The second project is aimed at testing atomic kinetics models for photoionized plasmas. Photoionization is an important process in many astrophysical plasmas and the spectral signatures are routinely used to infer astrophysical object's characteristics. However, the spectral synthesis models at the heart of these interpretations have been the subject of very limited experimental tests. Our current research examines photoionization of neon plasma subjected to radiation flux similar to the warm absorber that surrounds active galactic nuclei. The third project is a recent initiative aimed at producing a white dwarf photosphere in the laboratory. Emergent spectra from the photosphere are used to infer the star's effective temperature and surface gravity. The results depend on knowledge of H, He, and C spectral line profiles under conditions where complex physics such as quasi-molecule formation may be important

  7. Effective Materials Property Information Management for the 21st Century

    SciTech Connect

    Ren, Weiju; Cebon, David; Barabash, Oleg M

    2011-01-01

    This paper discusses key principles for the development of materials property information management software systems. There are growing needs for automated materials information management in various organizations. In part these are fuelled by the demands for higher efficiency in material testing, product design and engineering analysis. But equally important, organizations are being driven by the needs for consistency, quality and traceability of data, as well as control of access to proprietary or sensitive information. Further, the use of increasingly sophisticated nonlinear, anisotropic and multi-scale engineering analyses requires both processing of large volumes of test data for development of constitutive models and complex materials data input for Computer-Aided Engineering (CAE) software. And finally, the globalization of economy often generates great needs for sharing a single gold source of materials information between members of global engineering teams in extended supply-chains. Fortunately material property management systems have kept pace with the growing user demands and evolved to versatile data management systems that can be customized to specific user needs. The more sophisticated of these provide facilities for: (i) data management functions such as access, version, and quality controls; (ii) a wide range of data import, export and analysis capabilities; (iii) data pedigree traceability mechanisms; (iv) data searching, reporting and viewing tools; and (v) access to the information via a wide range of interfaces. In this paper the important requirements for advanced material data management systems, future challenges and opportunities such as automated error checking, data quality characterization, identification of gaps in datasets, as well as functionalities and business models to fuel database growth and maintenance are discussed.

  8. Effective Materials Property Information Management for the 21st Century

    NASA Technical Reports Server (NTRS)

    Ren, Weiju; Cebon, David; Arnold, Steve

    2009-01-01

    This paper discusses key principles for the development of materials property information management software systems. There are growing needs for automated materials information management in various organizations. In part these are fueled by the demands for higher efficiency in material testing, product design and engineering analysis. But equally important, organizations are being driven by the need for consistency, quality and traceability of data, as well as control of access to sensitive information such as proprietary data. Further, the use of increasingly sophisticated nonlinear, anisotropic and multi-scale engineering analyses requires both processing of large volumes of test data for development of constitutive models and complex materials data input for Computer-Aided Engineering (CAE) software. And finally, the globalization of economy often generates great needs for sharing a single "gold source" of materials information between members of global engineering teams in extended supply chains. Fortunately, material property management systems have kept pace with the growing user demands and evolved to versatile data management systems that can be customized to specific user needs. The more sophisticated of these provide facilities for: (i) data management functions such as access, version, and quality controls; (ii) a wide range of data import, export and analysis capabilities; (iii) data "pedigree" traceability mechanisms; (iv) data searching, reporting and viewing tools; and (v) access to the information via a wide range of interfaces. In this paper the important requirements for advanced material data management systems, future challenges and opportunities such as automated error checking, data quality characterization, identification of gaps in datasets, as well as functionalities and business models to fuel database growth and maintenance are discussed.

  9. Clinical Biospecimens: Reference Materials, Certified for Nominal Properties?

    PubMed Central

    2014-01-01

    This report makes the case for clinical biospecimens to be certified for nominal properties, in particular the diagnosis, and to attain the level of Reference Materials. Clinical certified biospecimens that are collected, processed, characterized, stored, and distributed by biobanks are urgently needed to facilitate diagnostic test development, evaluation, and quality assurance. Four examples are provided to illustrate this purpose and the certification approaches that could be applied are proposed. PMID:24749878

  10. Predicting the Highly Nonlinear Mechanical Properties of Polymeric Materials

    NASA Astrophysics Data System (ADS)

    Porter, David

    2009-06-01

    Over the past few years, we have developed models that calculate the highly nonlinear mechanical properties of polymers as a function of temperature, strain and strain rate from their molecular and morphological structure. A review of these models is presented here, with emphasis on combining the fundamental aspects of molecular physics that dictate these properties and the pragmatic need to make realistic predictions for our customers; the designer of new materials and the engineers who use these materials. The models calculate the highly nonlinear mechanical properties of polymers as a function of temperature, strain and strain rate from their molecular structure. The model is based upon the premise that mechanical properties are a direct consequence of energy stored and energy dissipated during deformation of a material. This premise is transformed into a consistent set of structure-property relations for the equation of state, EoS, and the engineering constitutive relations in a polymer by quantifying energy storage and loss at the molecular level of interactions between characteristic groups of atoms in a polymer. These relations are derived from a simple volumetric mean field Lennard-Jones potential function for the potential energy of intermolecular interactions in a polymer. First, properties such as temperature-volume relations and glass transition temperature are calculated directly from the potential function. Then, the `shock' EoS is derived simply by differentiating the potential function with respect to volume, assuming that the molecules cannot relax in the time scales of the deformation. The energy components are then used to predict the dynamic mechanical spectrum of a polymer in terms of temperature and rate. This can be transformed directly into the highly nonlinear stress-strain relations through yield. The constitutive relations are formulated as a set of analytical equations that predict properties directly in terms of a small set of

  11. INSTRUMENTS AND METHODS OF INVESTIGATION: Modification of material properties and coating deposition using plasma jets

    NASA Astrophysics Data System (ADS)

    Pogrebnyak, Alexander D.; Tyurin, Yu N.

    2005-05-01

    The review is concerned with the current status of research on the use of plasma jets for the modification of surface properties of metalware, as well as of investigations of doping and mass transfer of elements. The effect of thermal plasma parameters on the efficiency of surface processing of metal materials is discussed. The structure and properties of protective coatings produced by exposure to pulsed plasmas are analyzed. A new direction for the production of combined coatings is considered. Their structure and properties were studied by the example of Fe, Cu, steels, and alloys, including titanium alloys; the modification process was shown to be controllable by the action of pulsed plasma jets. The physical factors that affect the modification process and the coating deposition, and their effect on the structure and properties of metallic, ceramic - metal, and ceramic coatings were analyzed.

  12. Measurement of Mechanical Properties of Cantilever Shaped Materials

    PubMed Central

    Finot, Eric; Passian, Ali; Thundat, Thomas

    2008-01-01

    Microcantilevers were first introduced as imaging probes in Atomic Force Microscopy (AFM) due to their extremely high sensitivity in measuring surface forces. The versatility of these probes, however, allows the sensing and measurement of a host of mechanical properties of various materials. Sensor parameters such as resonance frequency, quality factor, amplitude of vibration and bending due to a differential stress can all be simultaneously determined for a cantilever. When measuring the mechanical properties of materials, identifying and discerning the most influential parameters responsible for the observed changes in the cantilever response are important. We will, therefore, discuss the effects of various force fields such as those induced by mass loading, residual stress, internal friction of the material, and other changes in the mechanical properties of the microcantilevers. Methods to measure variations in temperature, pressure, or molecular adsorption of water molecules are also discussed. Often these effects occur simultaneously, increasing the number of parameters that need to be concurrently measured to ensure the reliability of the sensors. We therefore systematically investigate the geometric and environmental effects on cantilever measurements including the chemical nature of the underlying interactions. To address the geometric effects we have considered cantilevers with a rectangular or circular cross section. The chemical nature is addressed by using cantilevers fabricated with metals and/or dielectrics. Selective chemical etching, swelling or changes in Young's modulus of the surface were investigated by means of polymeric and inorganic coatings. Finally to address the effect of the environment in which the cantilever operates, the Knudsen number was determined to characterize the molecule-cantilever collisions. Also bimaterial cantilevers with high thermal sensitivity were used to discern the effect of temperature variations. When appropriate

  13. Ocean acidification alters the material properties of Mytilus edulis shells.

    PubMed

    Fitzer, Susan C; Zhu, Wenzhong; Tanner, K Elizabeth; Phoenix, Vernon R; Kamenos, Nicholas A; Cusack, Maggie

    2015-02-01

    Ocean acidification (OA) and the resultant changing carbonate saturation states is threatening the formation of calcium carbonate shells and exoskeletons of marine organisms. The production of biominerals in such organisms relies on the availability of carbonate and the ability of the organism to biomineralize in changing environments. To understand how biomineralizers will respond to OA the common blue mussel, Mytilus edulis, was cultured at projected levels of pCO2 (380, 550, 750, 1000 µatm) and increased temperatures (ambient, ambient plus 2°C). Nanoindentation (a single mussel shell) and microhardness testing were used to assess the material properties of the shells. Young's modulus (E), hardness (H) and toughness (KIC) were measured in mussel shells grown in multiple stressor conditions. OA caused mussels to produce shell calcite that is stiffer (higher modulus of elasticity) and harder than shells grown in control conditions. The outer shell (calcite) is more brittle in OA conditions while the inner shell (aragonite) is softer and less stiff in shells grown under OA conditions. Combining increasing ocean pCO2 and temperatures as projected for future global ocean appears to reduce the impact of increasing pCO2 on the material properties of the mussel shell. OA may cause changes in shell material properties that could prove problematic under predation scenarios for the mussels; however, this may be partially mitigated by increasing temperature. PMID:25540244

  14. Effects of prestresses on mechanical properties of isotropic graphite materials

    NASA Astrophysics Data System (ADS)

    Oku, T.; Kurumada, A.; Imamura, Y.; Kawamata, K.; Shiraishi, M.

    1998-10-01

    Graphite materials which are used for plasma facing components and other components are subjected to stresses due to the high heat flux from the fusion plasma. Some mechanical properties of graphite materials can change due to the prestresses. The property changes should be considered for the design of the plasma facing components. The purpose of this study is to examine the effects of prestresses on the mechanical properties of isotropic graphite materials. Compressive prestresses were applied to two kinds of isotropic fine-grained graphites (IG-430 and IG-11) at 298 K (both), 1873 K (IG-11), 2273 K (IG-11) and 2283 K (IG-430). As a result, the decrease in Young's modulus for IG-430 due to high-temperature prestressing was 56% which was much larger than the 6.4% that was due to prestressing at 298 K. The results for IG-11 were the same as those for IG-430 graphite. This finding was considered to be due primarily to a difference in degree of the preferred orientation of crystallites in the graphite on the basis of the Bacon anisotropy factor (BAF) obtained from X-ray diffraction measurement of the prestressed specimens. Furthermore, high-temperature compressive prestressing produced an increase in the strength of the isotropic graphite, although room temperature prestressing produced no such effect. The results obtained here suggest that the isotropic graphite which is subjected to high-temperature compressive stresses can become anisotropic in service.

  15. Ocean acidification alters the material properties of Mytilus edulis shells

    PubMed Central

    Fitzer, Susan C.; Zhu, Wenzhong; Tanner, K. Elizabeth; Phoenix, Vernon R.; Kamenos, Nicholas A.; Cusack, Maggie

    2015-01-01

    Ocean acidification (OA) and the resultant changing carbonate saturation states is threatening the formation of calcium carbonate shells and exoskeletons of marine organisms. The production of biominerals in such organisms relies on the availability of carbonate and the ability of the organism to biomineralize in changing environments. To understand how biomineralizers will respond to OA the common blue mussel, Mytilus edulis, was cultured at projected levels of pCO2 (380, 550, 750, 1000 µatm) and increased temperatures (ambient, ambient plus 2°C). Nanoindentation (a single mussel shell) and microhardness testing were used to assess the material properties of the shells. Young's modulus (E), hardness (H) and toughness (KIC) were measured in mussel shells grown in multiple stressor conditions. OA caused mussels to produce shell calcite that is stiffer (higher modulus of elasticity) and harder than shells grown in control conditions. The outer shell (calcite) is more brittle in OA conditions while the inner shell (aragonite) is softer and less stiff in shells grown under OA conditions. Combining increasing ocean pCO2 and temperatures as projected for future global ocean appears to reduce the impact of increasing pCO2 on the material properties of the mussel shell. OA may cause changes in shell material properties that could prove problematic under predation scenarios for the mussels; however, this may be partially mitigated by increasing temperature. PMID:25540244

  16. Materials property definition and generation for carbon-carbon and carbon phenolic materials

    NASA Technical Reports Server (NTRS)

    Canfield, A. R.; Mathis, J. R.; Starrett, H. S.; Koenig, J. R.

    1987-01-01

    A data base program to generate statistically significant material-property data for carbon-carbon and carbon phenolic materials to be used in designs of Space Shuttle is described. The program, which will provide data necessary for thermal and stress modeling of Shuttle nozzle and exit cone structures, includes evaluation of tension, compression, shear strength, shear modulus, thermal expansion, thermal conductivity, permeability, and emittance for both materials; the testing of carbon phenolic materials also includes CTE, off-gassing, pyrolysis, and RTG. Materials to be tested will be excised from Space Shuttle inlet, throat, and exit cone billets and modified involute carbon-carbon exit cones; coprocessed blocks, panels, and cylinders will also be tested.

  17. Correlation of materials properties with the atomic density concept

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Based on the hypothesis that the number of atoms per unit volume, accurately calculable for any substance of known real density and chemical composition, various characterizing parameters (energy levels of electrons interacting among atoms of the same or different kinds, atomic mass, bond intensity) were chosen for study. A multiple exponential equation was derived to express the relationship. Various properties were examined, and correlated with the various parameters. Some of the properties considered were: (1) heat of atomization, (2) boiling point, (3) melting point, (4) shear elastic modulus of cubic crystals, (5) thermal conductivity, and (6) refractive index for transparent substances. The solid elements and alkali halides were the materials studied. It is concluded that the number of different properties can quantitively be described by a common group of parameters for the solid elements, and a wide variety of compounds.

  18. Hygrothermal Simulations of Foundations: Part 1 - Soil Material Properties

    SciTech Connect

    Pallin, Simon B; Kehrer, Manfred

    2013-01-01

    Hygrothermal performance of soils coupled to buildings is a complicated process. The computational approach for heat transfer via the ground is well defined (EN-ISO-13370:, 2007) together with simplified methods (Staszczuk, Radon, & Holm). Though the soil moisture transfer is generally ignored, it is proven not negligible (Janssen, Carmeliet, & Hens, 2004). Even though reliable material properties of soils are required to perform realistic hygrothermal calculations of soils coupled to buildings, such material properties have not been well defined in hygrothermal calculations tools. Typical building constructions which are greatly influenced by soils are basements, crawl spaces and slab on grade and reliable hygrothermal performance of such construction are highly requested; as it is ranked within the top 10 Building America Enclosure Research Ideas according to Enclosures STC - Residential Energy Efficiency Stakeholder Meeting, February 29, 2012 Austin, TX. There exists an extensive amount of measurements on soil properties in Soil Science though this information must be gathered as well as adapted to be applicable in Building Science and for hygrothermal simulation purposes. Soil properties are important when analyzing and designing both new building constructions and retrofitting measures, where the outer boundary of the buildings enclosure consists of soil materials. Concerning basement energy retrofits, interior solutions of improving the energy demand has to cooperate with the existing soil properties and must therefore be designed thereafter. In concerns of exterior retrofits, the soil material can be replaced, if needed, with a more suitable filling material, though this approach applies only for basement walls. The soil material beneath the basement floor can naturally not be replaced hence the soil properties of this part of the buildings enclosure still must be taken into consideration. This study is divided into several parts. The intention of the first

  19. A comparative evaluation of mechanical properties of nanofibrous materials

    NASA Astrophysics Data System (ADS)

    Lyubun, German P.; Bessudnova, Nadezda O.

    2014-01-01

    Restoration or replacement of lost or damaged hard tooth tissues remain a reconstructive clinical dentistry challenge. One of the most promising solutions to this problem is the development of novel concepts and methodologies of tissue engineering for the synthesis of three-dimensional graft constructs that are equivalent to original organs and tissues. This structural and functional compatibility can be reached by producing ultra-thin polymer filament scaffolds. This research aims through a series of studies to examine different methods of polymer filament material special preparation and test mechanical properties of the produced materials subjected to a tensile strain. Nanofibrous material preparation using chemically pure acetone and mixtures of ethanol/water has shown no significant changes in sample surface morphology. The high temperature impact on material morphology has resulted in the modification of fiber structure. In the course of mechanical tests it has been revealed the dependence of the material strength on the spinning solution compositions. The results achieved point to the possibility to develop nanofibrous materials with required parameters changing the methodology of spinning solution production.

  20. PREFACE: Workshop on Oxide Materials 2014: Novel Multifunctional Properties

    NASA Astrophysics Data System (ADS)

    Gómez, M. E.; Lopera, W.

    2015-07-01

    The 2014 Workshop on Oxide Materials: Novel Multifunctional Properties was held in Cali, Colombia, from September 15 to September 19 on the campus of Universidad del Valle. It was a great privilege to have had this workshop in Cali after the first workshop on oxide materials commemorating the first centennial of the discovery of the superconductivity in 2011. The meeting gathered an audience of 80 participants, 10 invited speakers with two or three plenary talks each, 20 short oral contributions, two poster sessions with 20 presentations each. This proceedings volume contains papers reported at the conference. The Proceedings of the 2014 Workshop on Oxide Materials: Novel Multifunctional Properties were edited by Maria Elena Gomez and Wilson Lopera with the assistance of Carlos William Sanchez and Albert Ortiz as copy editor. We are grateful for the financial support from COLCIENCIAS through research project COLCIENCIAS-UNIVALLE contract 002/2013; Universidad de Valle through Professor Ivan Ramos, Rector; the Faculty of Science with Professor Jaime Cantera, Dean; the Center of Excellence on Novel Materials with Professor Pedro Prieto, Director; ICETEX, and INTECO Ltda. Further details about the conference, including details of the invited speakers and plenary sessions are available in the PDF. Maria Elena Gómez, Editor Wilson Lopera, Editor

  1. Material properties from contours: New insights on object perception.

    PubMed

    Pinna, Baingio; Deiana, Katia

    2015-10-01

    In this work we explored phenomenologically the visual complexity of the material attributes on the basis of the contours that define the boundaries of a visual object. The starting point is the rich and pioneering work done by Gestalt psychologists and, more in detail, by Rubin, who first demonstrated that contours contain most of the information related to object perception, like the shape, the color and the depth. In fact, by investigating simple conditions like those used by Gestalt psychologists, mostly consisting of contours only, we demonstrated that the phenomenal complexity of the material attributes emerges through appropriate manipulation of the contours. A phenomenological approach, analogous to the one used by Gestalt psychologists, was used to answer the following questions. What are contours? Which attributes can be phenomenally defined by contours? Are material properties determined only by contours? What is the visual syntactic organization of object attributes? The results of this work support the idea of a visual syntactic organization as a new kind of object formation process useful to understand the language of vision that creates well-formed attribute organizations. The syntax of visual attributes can be considered as a new way to investigate the modular coding and, more generally, the binding among attributes, i.e., the issue of how the brain represents the pairing of shape and material properties. PMID:26072333

  2. Silk/nano-material hybrid: properties and functions

    NASA Astrophysics Data System (ADS)

    Steven, Eden; Lebedev, Victor; Laukhina, Elena; Laukhin, Vladimir; Alamo, Rufina G.; Rovira, Concepcio; Veciana, Jaume; Brooks, James S.

    2014-03-01

    Silk continues to emerge as a material of interest in electronics. In this work, the interaction between silk and conducting nano-materials are investigated. Simple fabrication methods, physical, electronic, thermal, and actuation properties are reported for spider silk / carbon nanotube (CNT-SS) and Bombyx mori / (BEDT-TTF)-based organic molecular conductor hybrids (ET-S). The CNT-SS fibers are produced via water and shear assisted method, resulting in fibers that are tough, custom-shapeable, flexible, and electrically conducting. For ET-S bilayer films, a layer transfer technique is developed to deposit linked crystallites of (BEDT-TTF)2I3 molecular conductor onto silk films, generating highly piezoresistive semi-transparent films. In both cases, the hybridization allows us to gain additional functions by harnessing the water-dependent properties of silk materials, for example, as humidity sensor and electrical current- or water-driven actuators. SEM, TEM, FT-IR, and resistance measurements under varying temperature, strain, and relative humidity reveal the synergistic interactions between the bio- and nano-materials. E.S. is supported by NSF-DMR 1005293.

  3. Bridging Microstructure, Properties and Processing of Polymer Based Advanced Materials

    SciTech Connect

    Li, Dongsheng; Ahzi, Said; Khaleel, Mohammad A.

    2012-01-01

    This is a guest editorial for a special issue in Journal of Engineering Materials and Technology. The papers collected in this special issue emphasize significant challenges, current approaches and future strategies necessary to advance the development of polymer-based materials. They were partly presented at the symposium of 'Bridging microstructure, properties and processing of polymer based advanced materials' in the TMS 2011 annual conference meeting, which was held in San Diego, US, on Feb 28 to March 3, 2011. This symposium was organized by the Pacific Northwest National Laboratory (USA) and the Institute of Mechanics of Fluids and Solids of the University of Strasbourg (France). The organizers were D.S. Li, S. Ahzi, and M. Khaleel.

  4. Corrosion and tribological properties of basalt fiber reinforced composite materials

    NASA Astrophysics Data System (ADS)

    Ha, Jin Cheol; Kim, Yun-Hae; Lee, Myeong-Hoon; Moon, Kyung-Man; Park, Se-Ho

    2015-03-01

    This experiment has examined the corrosion and tribological properties of basalt fiber reinforced composite materials. There were slight changes of weight after the occurring of corrosion based on time and H2SO4 concentration, but in general, the weight increased. It is assumed that this happens due to the basalt fiber precipitate. Prior to the corrosion, friction-wear behavior showed irregular patterns compared to metallic materials, and when it was compared with the behavior after the corrosion, the coefficient of friction was 2 to 3 times greater. The coefficient of friction of all test specimen ranged from 0.1 to 0.2. Such a result has proven that the basalt fiber, similar to the resin rubber, shows regular patterns regardless of time and H2SO4 concentration because of the space made between resins and reinforced materials.

  5. The effect of material properties on the seismic performance of Arch Dams

    NASA Astrophysics Data System (ADS)

    Sevim, B.

    2011-08-01

    The paper investigates the effect of material properties on the seismic performance of arch dam-reservoir-foundation interaction systems based on the Lagrangian approach using demand-capacity ratios. Type-5 arch dam is selected as a numerical application. The linear time history analyses of the arch dam-reservoir-foundation interaction system are carried out for different material properties. The foundation is taken into account as massless; behaviour of the reservoir is assumed to be linearly elastic, inviscid and irrotational. The north-south component of the Erzincan earthquake in 1992 is chosen as a ground motion. Dynamic equations of motions obtained from 3-D finite element modelling of the coupled system are solved by using the Newmark integration algorithm. The damage levels of the coupled system for the different material properties are demonstrated by using demand-capacity ratios and cumulative inelastic durations. The time histories and maximum values of the displacements and principal stresses, and performance curves, are obtained from linear analyses. It is clearly seen from the study that the different material properties affect the seismic behaviour of the dam.

  6. Ozone gas affects the physical and chemical properties of wheat (Triticum aestivum L.) starch

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ozone can oxidize hydroxyl groups present at C2, C3, and C6 positions on the starch molecule and affect its physicochemical properties. In this experiment, bread wheat flour and isolated wheat starch were treated with ozone gas (1,500 ppm, gas flow rate 2.5 L/minutes) for 45 minutes and 30 minutes, ...

  7. Preparation and properties on hollow nano-structured smoke material

    NASA Astrophysics Data System (ADS)

    Liu, Xiang-cui; Dai, Meng-yan; Fang, Guo-feng; Shi, Wei-dong; Cheng, Xiang; Liu, Hai-feng; Zhang, Tong

    2013-09-01

    In recent years, the weapon systems of laser guidance and infrared (IR) imaging guidance have been widely used in modern warfare because of their high precision and strong anti-interference. Notwithstanding, military smoke, as a rapid and effective passive jamming means, can effectively counteract the attack of enemy precision-guided weapons by scattering and absorbability. Conventional smoke has good attenuation capability only to visible light (0.4-0.76 μm), but hardly any effect to other electromagnetic wave band. The weapon systems of laser guidance and IR imaging guidance usually work in broad band, including near IR (1-3 μm), middle IR (3-5 μm), far IR (8-14 μm), and so on. Accordingly, exploiting and using new efficient obscurant materials, which is one of the important factors that develop smoke technology, have become a focus and attracted more interests around the world. Then nano-structured materials that are developing very quickly have turned into our new choice. Hollow nano-structured materials (HNSM) have many special properties because of their nano-size wall-thickness and sub-micron grain-size. After a lot of HNSM were synthesized in this paper, their physical and chemical properties, including grain size, phase composition, microstructure, optical properties and resistivity were tested and analysed. Then the experimental results of the optical properties showed that HNSM exhibit excellent wave-absorbing ability in ultraviolet, visible and infrared regions. On the basis of the physicochemmical properties, HNSM are firstly applied in smoke technology field. And the obscuration performance of HNSM smoke was tested in smoke chamber. The testing waveband included 1.06μm and 10.6μm laser, 3-5μm and 8-14μm IR radiation. Then the main parameters were obtained, including the attenuation rate, the transmission rate, the mass extinction coefficient, the efficiency obscuring time, and the sedimentation rate, etc. The main parameters of HNSM smoke were

  8. Tendon material properties vary and are interdependent among turkey hindlimb muscles.

    PubMed

    Matson, Andrew; Konow, Nicolai; Miller, Samuel; Konow, Pernille P; Roberts, Thomas J

    2012-10-15

    The material properties of a tendon affect its ability to store and return elastic energy, resist damage, provide mechanical feedback and amplify or attenuate muscle power. While the structural properties of a tendon are known to respond to a variety of stimuli, the extent to which material properties vary among individual muscles remains unclear. We studied the tendons of six different muscles in the hindlimb of Eastern wild turkeys to determine whether there was variation in elastic modulus, ultimate tensile strength and resilience. A hydraulic testing machine was used to measure tendon force during quasi-static lengthening, and a stress-strain curve was constructed. There was substantial variation in tendon material properties among different muscles. Average elastic modulus differed significantly between some tendons, and values for the six different tendons varied nearly twofold, from 829±140 to 1479±106 MPa. Tendons were stretched to failure, and the stress at failure, or ultimate tensile stress, was taken as a lower-limit estimate of tendon strength. Breaking tests for four of the tendons revealed significant variation in ultimate tensile stress, ranging from 66.83±14.34 to 112.37±9.39 MPa. Resilience, or the fraction of energy returned in cyclic length changes was generally high, and one of the four tendons tested was significantly different in resilience from the other tendons (range: 90.65±0.83 to 94.02±0.71%). An analysis of correlation between material properties revealed a positive relationship between ultimate tensile strength and elastic modulus (r(2)=0.79). Specifically, stiffer tendons were stronger, and we suggest that this correlation results from a constrained value of breaking strain, which did not vary significantly among tendons. This finding suggests an interdependence of material properties that may have a structural basis and may explain some adaptive responses observed in studies of tendon plasticity. PMID:22771746

  9. Selected odor compounds in cooked soymilk as affected by soybean materials and direct steam injection.

    PubMed

    Yuan, S H; Chang, S K C

    2007-09-01

    Soy odor is a major concern in the consumption of soymilk by Western consumers. The objectives of this study were to determine selected soy odor compounds as affected by soybean materials and direct steam injection and to determine if the steam-injection method affected overall cooked soy aroma of the soymilk and compared to the soymilk cooked by a traditional indirect method. Five varieties of soybeans with or without lipoxygenases were processed by direct-steam injection for up to 20 min at 100 degrees C. Eight selected odor compounds were analyzed by gas chromatography after extraction using a solid-phase micro-extraction (SPME) method. Hexanal, hexanol, 1-octen-3-ol, 1-octen-3-one, and trans-2-nonenal decreased whereas 2-pentylfuran and trans-2, trans-4-decadienal increased by boiling up to 20 min. The results showed that soybean variety was a significant factor to affect odor compositions. Direct steam injection cooked soymilk resulted in lower odor contents than a traditional indirect cooking method. The advantage of having a low odor composition in the heated soymilk products made from lipoxygenases-null soybean varieties could be attained by using normal soybean materials with direct steam injection. PMID:17995661

  10. Properties of granular analogue model materials: A community wide survey

    NASA Astrophysics Data System (ADS)

    Klinkmüller, Matthias; Schreurs, Guido; Rosenau, Matthias; Kemnitz, Helga

    2016-04-01

    We report the material properties of 26 granular analogue materials used in 14 analogue modelling laboratories. We determined physical characteristics such as bulk density, grain size distribution, and grain shape, and performed ring shear tests to determine friction angles and cohesion, and uniaxial compression tests to evaluate the compaction behaviour. Mean grain size of the materials varied between (c. 100 and 400 micrometer). Analysis of grain shape factors show that the four different classes of granular materials (14 quartz sands, 5 dyed quartz sands, 4 heavy mineral sands and 3 size fractions of glass beads) can be broadly divided into two groups consisting of 12 angular and 14 rounded materials. Grain shape has an influence on friction angles, with most angular materials having higher internal friction angles (between c. 35° and 40°) than rounded materials, whereas well-rounded glass beads have the lowest internal friction angles (between c. 25° and 30°). We interpret this as an effect of intergranular sliding versus rolling . Most angular materials have also higher basal friction angles (tested for a specific foil) than more rounded materials, suggesting that angular grains scratch and wear the foil., Most materials have a cohesion in the order of 10-100 Pa except for well-rounded glass beads, which show a trend towards a quasi-cohesionless (C <10 Pa) Coulomb-type material. The uniaxial confined compression tests reveal that rounded grains generally show less compaction than angular grains. We interpret this to be related to the initial packing density reached during sieving which is higher for rounded grains than for angular grains. Ring-shear test data show that angular grains undergo a longer strain-hardening phase than more rounded materials. This might explain why analogue models consisting of angular grains accommodate deformation in a more distributed manner prior to strain localisation than models consisting of rounded grains. Also, models

  11. Active material based active sealing technology: Part 1. Active seal requirements vs. active material actuator properties

    NASA Astrophysics Data System (ADS)

    Henry, Christopher P.; Carter, William; Herrera, Guillermo A.; McKnight, Geoffrey P.; Browne, Alan L.; Johnson, Nancy L.; Bazzi, Imad F.

    2010-04-01

    Current seals used for vehicle closures/swing panels are essentially flexible, frequently hollow structures whose designs are constrained by numerous requirements, many of them competing, including door closing effort (both air bind and seal compression), sound isolation, prevention of water leaks, and accommodation of variations in vehicle build. This paper documents the first portion of a collaborative research study/exploration of the feasibility of and approaches for using active materials with shape and stiffness changing attributes to produce active seal technologies, seals with improved performance. An important design advantage of an active material approach compared to previous active seal technologies is the distribution of active material regions throughout the seal length, which would enable continued active function even with localized failure. Included as a major focus of this study was the assessment of polymeric active materials because of their potential ease of integration into the current seal manufacturing process. In Part 1 of this study, which is documented in this paper, potential materials were evaluated in terms of their cost, activation mechanisms, and mechanical and actuation properties. Based on these properties, simple designs were proposed and utilized to help determine which materials are best suited for active seals. Shape memory alloys (SMA) and electroactive polymers (EAP) were judged to be the most promising.

  12. Effective Materials Property Information Management for the 21st Century

    SciTech Connect

    Ren, Weiju; Cebon, David; Arnold, Steve

    2010-01-01

    This paper discusses key principles for the development of materials property information management software systems. There are growing needs for automated materials information management in industry, research organizations and government agencies. In part these are fuelled by the demands for higher efficiency in material testing, product design and development and engineering analysis. But equally important, organizations are being driven to employ sophisticated methods and software tools for managing their mission-critical materials information by the needs for consistency, quality and traceability of data, as well as control of access to proprietary or sensitive information. Furthermore the use of increasingly sophisticated nonlinear, anisotropic and multi-scale engineering analysis approaches, particularly for composite materials, requires both processing of much larger volumes of test data for development of constitutive models and much more complex materials data input requirements for Computer-Aided Engineering (CAE) software. And finally, the globalization of engineering processes and outsourcing of design and development activities generates much greater needs for sharing a single gold source of materials information between members of global engineering teams in extended supply-chains. Fortunately material property management systems have kept pace with the growing user demands. They have evolved from hard copy archives, through simple electronic databases, to versatile data management systems that can be customized to specific user needs. The more sophisticated of these provide facilities for: (i) data management functions such as access control, version control, and quality control; (ii) a wide range of data import, export and analysis capabilities; (iii) mechanisms for ensuring that all data is traceable to its pedigree sources: details of testing programs, published sources, etc; (iv) tools for searching, reporting and viewing the data; and (v

  13. Strain weakening and localisation: material properties or boundary effects?

    NASA Astrophysics Data System (ADS)

    Ritter, Malte C.; Leever, Karen; Rosenau, Matthias; Oncken, Onno

    2015-04-01

    Strain weakening is commonly seen as one of the major causes of localisation of deformation into shear zones in brittle media. Several studies, both numerical and physical experiments, investigate its influence. Typically, these studies choose a certain model configuration and test various material properties and their influence on localisation in that particular configuration. This approach, however, does not take into account the fundamental importance of boundary conditions on the processes of localisation, weakening and overall shear zone evolution. To address this issue, we perform physical experiments in granular materials. We create shear fractures within a sample of granular material (sand) using different experimental apparatuses that apply different boundary conditions. Among them are standard machines such as a Ring-Shear Tester and the classical Riedel set up, as well as a newly designed set up. Boundary conditions can be varied from purely kinematic to more dynamically controlled and from laterally confined to unconfined. Nevertheless, the final result of deformation is an approximately straight strike-slip shear zone in all cases. We monitor boundary force (i. e. material strength) and, where experimentally accessible, strain, at high temporal resolution during deformation. With our different set ups we are able to produce very different patterns of deformation and weakening in the same material under the same constant rate of shearing and with the same final result. Observed patterns span from nearly instantaneous formation of one single through-going shear zone to slow, step-wise growth of a complex network of interacting cracks. Weakening in all cases matches well the structural evolution. Variations of weakening for a given material in different set ups are larger than for different materials in a given set up. Our results show that for a given material the style and rate of localisation can change drastically, depending on only slight changes of

  14. Dry heat treatment affects wheat bran surface properties and hydration kinetics.

    PubMed

    Jacobs, Pieter J; Hemdane, Sami; Delcour, Jan A; Courtin, Christophe M

    2016-07-15

    Heat stabilization of wheat bran aims at inactivation of enzymes which may cause rancidity and processability issues. Such treatments may however cause additional unanticipated phenomena which may affect wheat bran technological properties. In this work, the impact of toasting on wheat bran hydration capacity and hydration kinetics was studied. Hydration properties were assessed using the Enslin-Neff and drainage centrifugation water retention capacity methods, thermogravimetric analysis and contact angle goniometry, next to more traditional methods. While equilibrium hydration properties of bran were not affected by the heat treatment, the rate at which the heat treated bran hydrated was, however, very significantly reduced compared to the untreated bran. This phenomenon was found to originate from the formation of a lipid coating during the treatment rendering the bran surface hydrophobic. These insights help to understand and partially account for the modified processability of heat treated bran in food applications. PMID:26948645

  15. Method and apparatus for assessing material properties of sheet-like materials

    DOEpatents

    Telschow, Kenneth L.; Deason, Vance A.

    2002-01-01

    Apparatus for producing an indication of a material property of a sheet-like material according to the present invention may comprise an excitation source for vibrating the sheet-like material to produce at least one traveling wave therein. A light source configured to produce an object wavefront and a reference wavefront directs the object wavefront toward the sheet-like material to produce a modulated object wavefront. A modulator operatively associated with the reference wavefront modulates the reference wavefront in synchronization with the traveling wave on the sheet-like material to produce a modulated reference wavefront. A sensing medium positioned to receive the modulated object wavefront and the modulated reference wavefront produces an image of the traveling wave in the sheet-like material, the image of the anti-symmetric traveling wave being related to a displacement amplitude of the anti-symmetric traveling wave over a two-dimensional area of the vibrating sheet-like material. A detector detects the image of the traveling wave in the sheet-like material.

  16. Nonlinear optical properties and nonlinear optical probes of organic materials

    NASA Astrophysics Data System (ADS)

    Meredith, Gerald R.

    1992-02-01

    Nonlinear optical processes and electro-optical effects are expected to have increasing importance as the information age matures and photonics augment electronics in various high density and high bandwidth technologies. Whereas for electronics the emphasis is in construction of smaller device structures from a few parent materials, for organic materials the direction of materials research has been reversed. For some time it's been known that some molecular structures engender exceptionally large molecular nonlinear-polarization responses. If such molecules could be assembled in convenient, versatile, and reliable ways, the resulting materials would be very useful or even enabling in various photonics applications. The mature science and art of chemistry allows very good control over molecular composition and structure and, as will be illustrated in this talk, our knowledge of hyperpolarizability structure- property relationships is advancing rapidly. However, the science of fabrication and arrangement in molecular ensembles and polymers is rather primitive. Thus the goal to develop the appropriately structured materials for utilization in nonlinear and electro-optics has fostered the widespread use of nonlinear optical processes to probe the nature of supramolecular order and assembly. Examples of intrinsic and artificially assembled structures of crystals, molecular aggregates, polymeric orientational electrets and molecular mono- and multi-layer thin films will be shown. Nonlinear optical processes, primarily second-harmonic generation, provide unique probes of these structures, their assembly, and evolution.

  17. Synthesis, processing and properties of materials for SOFCs

    SciTech Connect

    Bates, J.L.; Armstrong, T.A.; Kingsley, J.J.; Pederson, L.R.

    1994-03-01

    The synthesis and processing methods of complex oxide materials can significantly influence use in solid oxide fuel cells (SOFCs). This paper discusses (1) effects of powder synthesis and conditioning on fabrication, i.e., sintering, where close, reproducible control of composition and structure are required, and (2) influences on electrical, mechanical, structural and electrochemical properties that can influence SOFC performance. Examples are given for chromites, manganites and related oxides used as interconnections and electrodes in SOFCs. Materials, from source to incorporation into the fuel cell and generator, is a major issue in the development of solid oxide fuel cells (SOFCs). An integral part of this is the synthesis from chemicals and other virgin materials, generally as an oxide or metal powder, which can become a SOFC component. In some instances, such as with electrochemical vapor deposition, the component is formed directly from the chemicals. The synthesized materials are then conditioned and processes prior to fabrication into the fuel cell component, either separately or in conjunction with other material components.

  18. Synthesis and Engineering Materials Properties of Fluid Phase Chemical Hydrogen Storage Materials for Automotive Applications

    SciTech Connect

    Choi, Young Joon; Westman, Matthew P.; Karkamkar, Abhijeet J.; Chun, Jaehun; Ronnebro, Ewa

    2015-09-01

    Among candidates for chemical hydrogen storage in PEM fuel cell automotive applications, ammonia borane (AB, NH3BH3) is considered to be one of the most promising materials due to its high practical hydrogen content of 14-16 wt%. This material is selected as a surrogate chemical for a hydrogen storage system. For easier transition to the existing infrastructure, a fluid phase hydrogen storage material is very attractive and thus, we investigated the engineering materials properties of AB in liquid carriers for a chemical hydrogen storage slurry system. Slurries composed of AB and high temperature liquids were prepared by mechanical milling and sonication in order to obtain stable and fluidic properties. Volumetric gas burette system was adopted to observe the kinetics of the H2 release reactions of the AB slurry and neat AB. Viscometry and microscopy were employed to further characterize slurries engineering properties. Using a tip-sonication method we have produced AB/silicone fluid slurries at solid loadings up to 40wt% (6.5wt% H2) with viscosities less than 500cP at 25°C.

  19. Soil Properties Affecting the Reductive Capacity of Volcanic Ash Soils in Korea

    NASA Astrophysics Data System (ADS)

    Chon, C.; Ahn, J.; Kim, K.; Park, K.

    2008-12-01

    Volcanic ash soils or Andisols have distinct chemical and mineralogical properties. The unique chemical properties of Andisols are due to their Al-rich elemental composition, the highly reactive nature of their colloidal fractions, and their large surface area. The soils that developed from volcanic ash on Jeju Island, Korea, were classified as typical Andisols. The soils had an acidic pH, high water content, high organic matter, and clay-silty texture. The crystalline minerals in the samples were mainly ferromagnesian minerals, such as olivine and pyroxene, and iron oxides, such as magnetite and hematite derived from basaltic materials. A large amount of gibbsite was found in the subsurface horizon as a secondary product of the migration of excess Al. In addition, we found that considerable amounts of poorly ordered minerals like allophane and ferrihydrite were present in the Jeju soils. The SiO2 contents were lower than those of other soil orders, while the Al2O3 and Fe2O3 contents were higher. These results reflect some of the important chemical properties of Andisols. The chromium (VI/III) redox couple was used in the reductive capacity measurement. The mean reductive capacity of the Jeju soils was 6.53 mg/L reduced Cr(VI), which is 5.1 times higher than that of non-volcanic ash soils from inland Korea. The reductive capacity of the inland soils was correlated with the total carbon content. Such a high capacity for the reduction of soluble Cr(VI) must also be due to the relatively high carbon contents of the Jeju soils. Nevertheless, despite having 20 times higher total carbon contents, there was no correlation between the reductive capacity of the Jeju soils and the carbon content. These results imply that the reductive capacity of Jeju soils is not only controlled by the carbon content, but is also affected by other soil properties. Correlations of the reductive capacity with major elements showed that Al and Fe were closely connected to the reductive

  20. Effects of material properties and object orientation on precision grip kinematics.

    PubMed

    Paulun, Vivian C; Gegenfurtner, Karl R; Goodale, Melvyn A; Fleming, Roland W

    2016-08-01

    Successfully picking up and handling objects requires taking into account their physical properties (e.g., material) and position relative to the body. Such features are often inferred by sight, but it remains unclear to what extent observers vary their actions depending on the perceived properties. To investigate this, we asked participants to grasp, lift and carry cylinders to a goal location with a precision grip. The cylinders were made of four different materials (Styrofoam, wood, brass and an additional brass cylinder covered with Vaseline) and were presented at six different orientations with respect to the participant (0°, 30°, 60°, 90°, 120°, 150°). Analysis of their grasping kinematics revealed differences in timing and spatial modulation at all stages of the movement that depended on both material and orientation. Object orientation affected the spatial configuration of index finger and thumb during the grasp, but also the timing of handling and transport duration. Material affected the choice of local grasp points and the duration of the movement from the first visual input until release of the object. We find that conditions that make grasping more difficult (orientation with the base pointing toward the participant, high weight and low surface friction) lead to longer durations of individual movement segments and a more careful placement of the fingers on the object. PMID:27016090

  1. Tooth and bone deformation: structure and material properties by ESPI

    NASA Astrophysics Data System (ADS)

    Zaslansky, Paul; Shahar, Ron; Barak, Meir M.; Friesem, Asher A.; Weiner, Steve

    2006-08-01

    In order to understand complex-hierarchical biomaterials such as bones and teeth, it is necessary to relate their structure and mechanical-properties. We have adapted electronic speckle pattern-correlation interferometry (ESPI) to make measurements of deformation of small water-immersed specimens of teeth and bones. By combining full-field ESPI with precision mechanical loading we mapped sub-micron displacements and determined material-properties of the samples. By gradually and elastically compressing the samples, we compensate for poor S/N-ratios and displacement differences of about 100nm were reliably determined along samples just 2~3mm long. We produced stress-strain curves well within the elastic performance range of these materials under biologically relevant conditions. For human tooth-dentin, Young's modulus in inter-dental areas of the root is 40% higher than on the outer sides. For cubic equine bone samples the compression modulus of axial orientations is about double the modulus of radial and tangential orientations (20 GPa versus 10 GPa respectively). Furthermore, we measured and reproduced a surprisingly low Poisson's ratio, which averaged about 0.1. Thus the non-contact and non-destructive measurements by ESPI produce high sensitivity analyses of mechanical properties of mineralized tissues. This paves the way for mapping deformation-differences of various regions of bones, teeth and other biomaterials.

  2. Electromagnetic properties of Permendur granular composite materials containing flaky particles

    NASA Astrophysics Data System (ADS)

    Kasagi, Teruhiro; Tsutaoka, Takanori; Hatakeyama, Kenichi

    2014-10-01

    Electromagnetic properties of Permendur (Fe50Co50 alloy) granular composite materials containing flaky particle have been studied from the RF to microwave frequency range. Properties of the flaky particle composites were compared with the spherical particle ones. The electrical conductivity of the flaky particle composite was higher than that of the spherical particle composite at the same particle content. An insulator to metal transition was observed at the percolation threshold φc in both composites. The φc of the flaky particle composite was lower than that of the spherical one. The relative complex permittivity indicates that the insulating state has dielectric properties. For the spherical particle composite, the permittivity enhancement caused by particle cluster formation can be described by the effective cluster model (ECM). The enhancement of the dielectric constant in the flaky particle composite is larger than the ECM prediction. A negative permittivity spectrum indicating a low frequency plasmonic state was observed in the metallic 70 vol. % flaky particle composite. The relative complex permeability spectra of the flaky particle composite are different from those of the spherical one. The flaky particle composite shows a larger permeability value and lower permeability dispersion frequency than the spherical particle composite. Negative permeability spectra were observed in the both composite materials. The negative permeability frequency band of the flaky particle composite is lower than that of the spherical particle composite owing to the demagnetizing field effect.

  3. Processing and nanostructure influences on mechanical properties of thermoelectric materials

    NASA Astrophysics Data System (ADS)

    Schmidt, Robert David

    Thermoelectric (TE) materials are materials that can generate an electric current from a thermal gradient, with possible service in recovery of waste heat such as engine exhaust. Significant progress has been made in improving TE conversion efficiency, typically reported according to the figure of merit, ZT, with several recent papers publishing ZT values above 2. Furthermore, cost reductions may be made by the use of lower cost elements such as Mg, Si, Sn, Pb, Se and S in TE materials, while achieving ZT values between 1.3 and 1.8. To be used in a device, the thermoelectric material must be able to withstand the applied thermal and mechanical forces without failure. However, these materials are brittle, with low fracture toughness typically less than 1.5 MPa-m1/2, and often less than 0.5 MPa-m1/2. For comparison, window glass is approximately 0.75 MPa-m1/2. They have been optimized with nanoprecipitates, nanoparticles, doping, alterations in stoichiometry, powder processing and other techniques, all of which may alter the mechanical properties. In this study, the effect of SiC nanoparticle additions in Mg2Si, SnTe and Ag nanoparticle additions in the skutterudite Ba0.3Co 4Sb12 on the elastic moduli, hardness and fracture toughness are measured. Large changes (˜20%) in the elastic moduli in SnTe 1+x as a function of x at 0 and 0.016 are shown. The effect on mechanical properties of doping and precipitates of CdS or ZnS in a PbS or PbSe matrix have been reported. Changes in sintering behavior of the skutterudite with the Ag nanoparticle additions were explored. Possible liquid phase sintering, with associated benefits in lower processing temperature, faster densification and lower cost, has been shown. A technique has been proposed for determining additional liquid phase sintering aids in other TE materials. The effects of porosity, grain size, powder processing method, and sintering method were explored with YbAl3 and Ba0.3Co4Sb 12, with the porosity dependence of

  4. Oxide Thermoelectric Materials: A Structure-Property Relationship

    NASA Astrophysics Data System (ADS)

    Nag, Abanti; Shubha, V.

    2014-04-01

    Recent demand for thermoelectric materials for power harvesting from automobile and industrial waste heat requires oxide materials because of their potential advantages over intermetallic alloys in terms of chemical and thermal stability at high temperatures. Achievement of thermoelectric figure of merit equivalent to unity ( ZT ≈ 1) for transition-metal oxides necessitates a second look at the fundamental theory on the basis of the structure-property relationship giving rise to electron correlation accompanied by spin fluctuation. Promising transition-metal oxides based on wide-bandgap semiconductors, perovskite and layered oxides have been studied as potential candidate n- and p-type materials. This paper reviews the correlation between the crystal structure and thermoelectric properties of transition-metal oxides. The crystal-site-dependent electronic configuration and spin degeneracy to control the thermopower and electron-phonon interaction leading to polaron hopping to control electrical conductivity is discussed. Crystal structure tailoring leading to phonon scattering at interfaces and nanograin domains to achieve low thermal conductivity is also highlighted.

  5. Learning to apply models of materials while explaining their properties

    NASA Astrophysics Data System (ADS)

    Karpin, Tiia; Juuti, Kalle; Lavonen, Jari

    2014-09-01

    Background:Applying structural models is important to chemistry education at the upper secondary level, but it is considered one of the most difficult topics to learn. Purpose:This study analyses to what extent in designed lessons students learned to apply structural models in explaining the properties and behaviours of various materials. Sample:An experimental group is 27 Finnish upper secondary school students and control group included 18 students from the same school. Design and methods:In quasi-experimental setting, students were guided through predict, observe, explain activities in four practical work situations. It was intended that the structural models would encourage students to learn how to identify and apply appropriate models when predicting and explaining situations. The lessons, organised over a one-week period, began with a teacher's demonstration and continued with student experiments in which they described the properties and behaviours of six household products representing three different materials. Results:Most students in the experimental group learned to apply the models correctly, as demonstrated by post-test scores that were significantly higher than pre-test scores. The control group showed no significant difference between pre- and post-test scores. Conclusions:The findings indicate that the intervention where students engage in predict, observe, explain activities while several materials and models are confronted at the same time, had a positive effect on learning outcomes.

  6. Mechanical properties of irradiated multi-phase polycrystalline BCC materials

    NASA Astrophysics Data System (ADS)

    Song, Dingkun; Xiao, Xiazi; Xue, Jianming; Chu, Haijian; Duan, Huiling

    2015-04-01

    Structure materials under severe irradiations in nuclear environments are known to degrade because of irradiation hardening and loss of ductility, resulting from irradiation-induced defects such as vacancies, interstitials and dislocation loops, etc. In this paper, we develop an elastic-viscoplastic model for irradiated multi-phase polycrystalline BCC materials in which the mechanical behaviors of individual grains and polycrystalline aggregates are both explored. At the microscopic grain scale, we use the internal variable model and propose a new tensorial damage descriptor to represent the geometry character of the defect loop, which facilitates the analysis of the defect loop evolutions and dislocation-defect interactions. At the macroscopic polycrystal scale, the self-consistent scheme is extended to consider the multiphase problem and used to bridge the individual grain behavior to polycrystal properties. Based on the proposed model, we found that the work-hardening coefficient decreases with the increase of irradiation-induced defect loops, and the orientation/loading dependence of mechanical properties is mainly attributed to the different Schmid factors. At the polycrystalline scale, numerical results for pure Fe match well with the irradiation experiment data. The model is further extended to predict the hardening effect of dispersoids in oxide-dispersed strengthened steels by the considering the Orowan bowing. The influences of grain size and irradiation are found to compete to dominate the strengthening behaviors of materials.

  7. Mechanical properties of composite materials with integrated embedded sensor networks

    NASA Astrophysics Data System (ADS)

    Schaaf, Kristin; Cook, Ben; Ghezzo, Fabrizia; Starr, Anthony; Nemat-Nasser, Sia

    2005-05-01

    We present efforts to develop structural composite materials which include networks of embedded sensors with decision-making capabilities that extend the functionality of the composite materials to be information-aware. The next generation of structural systems will include the capability to acquire, process, and if necessary respond to structural or other types of information. We present work related to the development of embedded arrays of miniature electronic-based microsensors within a structural composite materials, such as GFRP. Although the scale and power consumption of such devices continues to decrease while increasing the functionality, the size of these devices remain large relative the typical scale of the reinforcing fibers and the interlayer spacing. Therefore, the question of the impact of those devices on the various mechanical properties is relevant and important. We present work on characterizing some of those effects in specific systems where sensors, or suitable dummy sensors, are arrayed with ~1 cm spacing between elements. The typical size of the microelectronic sensing element is ~1 mm, and here is orthorhombic. Of particular importance are the effects of inclusion of such devices on strength or fatigue properties of the base composite. Our work seeks to characterize these effects for 1 and 2 dimensional arrays lying in planes normal to the thickness direction in laminated composites. We also seek to isolate the effects due to the sensing elements and the required interconnections that represent the power-carrying and data communications capabilities of the embedded network.

  8. Infrared optical properties of Mars soil analog materials: Palagonites

    NASA Technical Reports Server (NTRS)

    Roush, Ted L.

    1992-01-01

    The globally distributed bright soils on Mars represent products of chemical alteration of primary igneous materials. As such, understanding the chemistry and mineralogy of these soils provides clues about the nature of the parent materials and the type, duration, and extent of the chemical weathering environments on Mars. Such clues are key in developing an understanding of the interior and surficial processes that have operated throughout Mars' history to yield the surface as it is currently observed. The generally homogeneous nature of these soils is illustrated by a variety of observational data. These data include (1) direct determination of elemental abundances by the X-ray fluorescence instruments on both Viking Landers, (2) Earth-based telescopic observations, and (3) space-based observations. Based on their spectral properties in the visible and near-infrared, terrestrial palagonitic soils have been suggested as analogs for the bright regions on Mars. Palagonites represent the weathering products of basaltic glass and as such are composed of a variety of minerals/materials. In order to gain an understanding regarding the chemical, mineralogical, and spectral properties of a broad suite of palagonites, several samples were collected from the eastern and central regions of the island of Hawaii.

  9. Effects of temperature distribution and elastic properties of materials on gas-turbine-disk stresses

    NASA Technical Reports Server (NTRS)

    Holms, Arthur G; Faldetta, Richard D

    1947-01-01

    Calculations were made to determine the influence of changes in temperature distribution and in elastic material properties on calculated elastic stresses for a typical gas-turbine disk. Severe temperature gradients caused thermal stresses of sufficient magnitude to reduce the operating safety of the disk. Small temperature gradients were found to be desirable because they produced thermal stresses that subtracted from the centrifugal stresses in the region of the rim. The thermal gradients produced a tendency for a severe stress condition to exist near the rim but this stress condition could be shifted away from the region of blade attachment by altering the temperature distribution. The investigation of elastic material properties showed that centrifugal stresses are slightly affected by changes in modulus of elasticity, but that thermal stresses are approximately proportional to modulus of elasticity and to coefficient of thermal expansion.

  10. Affective Properties of Mothers' Speech to Infants With Hearing Impairment and Cochlear Implants

    PubMed Central

    Bergeson, Tonya R.; Xu, Huiping; Kitamura, Christine

    2015-01-01

    Purpose The affective properties of infant-directed speech influence the attention of infants with normal hearing to speech sounds. This study explored the affective quality of maternal speech to infants with hearing impairment (HI) during the 1st year after cochlear implantation as compared to speech to infants with normal hearing. Method Mothers of infants with HI and mothers of infants with normal hearing matched by age (NH-AM) or hearing experience (NH-EM) were recorded playing with their infants during 3 sessions over a 12-month period. Speech samples of 25 s were low-pass filtered, leaving intonation but not speech information intact. Sixty adults rated the stimuli along 5 scales: positive/negative affect and intention to express affection, to encourage attention, to comfort/soothe, and to direct behavior. Results Low-pass filtered speech to HI and NH-EM groups was rated as more positive, affective, and comforting compared with the such speech to the NH-AM group. Speech to infants with HI and with NH-AM was rated as more directive than speech to the NH-EM group. Mothers decreased affective qualities in speech to all infants but increased directive qualities in speech to infants with NH-EM over time. Conclusions Mothers fine-tune communicative intent in speech to their infant's developmental stage. They adjust affective qualities to infants' hearing experience rather than to chronological age but adjust directive qualities of speech to the chronological age of their infants. PMID:25679195

  11. Variation in Biofilm Stability with Decreasing pH Affects Porous Medium Hydraulic Properties

    NASA Astrophysics Data System (ADS)

    Kirk, M. F.; Santillan, E. F.; McGrath, L. K.; Altman, S. J.

    2010-12-01

    Changes to microbial communities caused by subsurface CO2 injection may have many consequences, including possible impacts to CO2 transport. We used column experiments to examine how decreasing pH, a geochemical change associated with CO2 injection, will affect biofilm stability and ultimately the hydraulic properties of porous media. Columns consisted of 1 mm2 square capillary tubes filled with 105-150 µm diameter glass beads. Artificial groundwater medium containing 1 mM glucose was pumped through the columns at a rate of 0.01 mL/min (q = 14.4 m/day; Re = 0.03). Columns were inoculated with 3 × 10^8 CFU (avg.) of Pseudomonas fluorescens, a model biofilm former, transformed with a green fluorescent protein. Biomass distribution and transport was examined using scanning laser confocal microscopy and effluent plating. Variation in the bulk hydraulic properties of the columns was measured using manometers. In an initial experiment, biofilm growth was allowed to occur for seven days in medium with pH 7.3. Within this period, cells uniformly coated bead surfaces, effluent cell numbers stabilized at 1 × 10^9 CFU/mL, and hydraulic conductivity (K) decreased 77%. Next, medium with pH 4 was introduced. As a result, biomass within the reactor redistributed from bead surfaces to pores, effluent cell numbers decreased to 3 × 10^5 CFU/mL, and K decreased even further (>94% reduction). This decreased K was maintained until the experiment was terminated, seven days after introducing low pH medium. These results suggest that changes in biomass distribution as a result of decreased pH may initially limit transport of solubility-trapped CO2 following CO2 injection. Experiments in progress and planned will test this result in more detail and over longer periods of time. This material is based upon work supported as part of the Center for Frontiers of Subsurface Energy Security, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office

  12. Mesostructured Composite Materials with Electrically Tunable Upconverting Properties.

    PubMed

    Mundoor, Haridas; Smalyukh, Ivan I

    2015-11-01

    A promising approach of designing mesostructured materials with novel physical behavior is to combine unique optical and electronic properties of solid nanoparticles with long-range ordering and facile response of soft matter to weak external stimuli. Here, orientationally ordered nematic liquid crystalline dispersions of rod-like upconversion nanoparticles are designed, practically realized, and characterized. Boundary conditions on particle surfaces, defined through surface functionalization, promote spontaneous unidirectional self-alignment of the dispersed rod-like nanoparticles, mechanically coupled to the molecular ordering direction of the thermotropic nematic liquid crystal host. As host is electrically switched at low voltages ≈ 1 V, nanorods rotate, yielding tunable upconversion and polarized luminescence properties of the composite. Spectral and polarization dependencies are characterized and explained through invoking models of electrical switching of liquid crystals and upconversion dependence on crystalline matrices of nanorods, and their potential practical uses are discussed. PMID:26332163

  13. Research on lunar materials. [optical, chemical, and electrical properties

    NASA Technical Reports Server (NTRS)

    Gold, T.

    1978-01-01

    Abstracts of 14 research reports relating to investigations of lunar samples are presented. The principal topics covered include: (1) optical properties of surface and core samples; (2) chemical composition of the surface layers of lunar grains: Auger electron spectroscopy of lunar soil and ground rock samples; (3) high frequency electrical properties of lunar soil and rock samples and their relevance for the interpretation of lunar radar observations; (4) the electrostatic dust transport process; (5) secondary electron emission characteristics of lunar soil samples and their relevance to the dust transportation process; (6) grain size distribution in surface soil and core samples; and (7) the optical and chemical effects of simulated solar wind (2keV proton and a particle radiation) on lunar material.

  14. Hygrothermal Simulation of Foundations: Part 1 - Soil Material Properties

    SciTech Connect

    Kehrer, Manfred; Pallin, Simon B

    2012-10-01

    The hygrothermal performance of soils coupled to buildings is a complicated process. A computational approach for heat transfer through the ground has been well defined (EN ISO 13370:2007, 2007), and simplified methods have been developed (Staszczuk, Radon, and Holm 2010). However, these approaches generally ignore the transfer of soil moisture, which is not negligible (Janssen, Carmeliet, and Hens 2004). This study is divided into several parts. The intention of the first part is to gather, comprehend and adapt soil properties from Soil Science. The obtained information must be applicable to related tasks in Building Science and validated with hygrothermal calculation tools. Future parts of this study will focus on the validation aspect of the soil properties to be implemented. Basic changes in the software code may be requested at this time. Different types of basement construction will be created with a hygrothermal calculation tool, WUFI. Simulations from WUFI will be compared with existing or ongoing measurements. The intentions of the first part of this study have been fulfilled. The soil properties of interest in Building Science have been defined for 12 different soil textures. These properties will serve as input parameters when performing hygrothermal calculations of building constructions coupled to soil materials. The reliability of the soil parameters will be further evaluated with measurements in Part 2.

  15. Mechanical Properties and Simulated Wear of Provisional Resin Materials.

    PubMed

    Takamizawa, T; Barkmeier, W W; Tsujimoto, A; Scheidel, D; Erickson, R L; Latta, M A; Miyazaki, M

    2015-01-01

    The purpose of this study was to determine flexural properties and erosive wear behavior of provisional resin materials. Three bis-acryl base provisional resins-1) Protemp Plus (PP), 2) Integrity (IG), 3) Luxatemp Automix Plus (LX)-and a conventional poly(methylmethacrylate) (PMMA) resin, UniFast III (UF), were evaluated. A resin composite, Z100 Restorative (Z1), was included as a benchmark material. Six specimens for each of the four materials were used to determine flexural strength and elastic modulus according to ISO Standard 4049. Twelve specimens for each material were used to examine wear using a generalized wear simulation model. The test materials were each subjected to wear challenges of 25,000, 50,000, 100,000, and 200,000 cycles in a Leinfelder-Suzuki (Alabama) wear simulator. The materials were placed in custom cylinder-shaped stainless-steel fixtures, and wear was generated using a cylindrical-shaped flat-ended stainless-steel antagonist in a slurry of nonplasticized PMMA beads. Wear (mean facet depth [μm] and volume loss [mm(3)]) was determined using a noncontact profilometer (Proscan 2100) with Proscan and AnSur 3D software. The laboratory data were evaluated using two-way analysis of variance (ANOVA; factors: 1) material and 2) cycles) followed by Tukey HSD post hoc test (α=0.05). The flexural strength ranged from 68.2 to 150.6 MPa, and the elastic modulus ranged from 2.0 to 15.9 GPa. All of the bis-acryl provisional resins (PP, IG, and LX) demonstrated significantly higher values than the PMMA resin (UF) in flexural strength and elastic modulus (p<0.05). However, there was no significant difference (p>0.05) in flexural properties among three bis-acryl base provisional resins (PP, IG, and LX). Z1 demonstrated significantly (p<0.05) higher flexural strength and elastic modulus than the other materials tested. The results for mean facet wear depth (μm) and standard deviations (SD) for 200,000 cycles were as follows: PP, 22.4 (5.0); IG, 51.0 (6

  16. Process design of press hardening with gradient material property influence

    SciTech Connect

    Neugebauer, R.; Schieck, F.; Rautenstrauch, A.

    2011-05-04

    Press hardening is currently used in the production of automotive structures that require very high strength and controlled deformation during crash tests. Press hardening can achieve significant reductions of sheet thickness at constant strength and is therefore a promising technology for the production of lightweight and energy-efficient automobiles. The manganese-boron steel 22MnB5 have been implemented in sheet press hardening owing to their excellent hot formability, high hardenability, and good temperability even at low cooling rates. However, press-hardened components have shown poor ductility and cracking at relatively small strains. A possible solution to this problem is a selective increase of steel sheet ductility by press hardening process design in areas where the component is required to deform plastically during crash tests. To this end, process designers require information about microstructure and mechanical properties as a function of the wide spectrum of cooling rates and sequences and austenitizing treatment conditions that can be encountered in production environments. In the present work, a Continuous Cooling Transformation (CCT) diagram with corresponding material properties of sheet steel 22MnB5 was determined for a wide spectrum of cooling rates. Heating and cooling programs were conducted in a quenching dilatometer. Motivated by the importance of residual elasticity in crash test performance, this property was measured using a micro-bending test and the results were integrated into the CCT diagrams to complement the hardness testing results. This information is essential for the process design of press hardening of sheet components with gradient material properties.

  17. Process design of press hardening with gradient material property influence

    NASA Astrophysics Data System (ADS)

    Neugebauer, R.; Schieck, F.; Rautenstrauch, A.

    2011-05-01

    Press hardening is currently used in the production of automotive structures that require very high strength and controlled deformation during crash tests. Press hardening can achieve significant reductions of sheet thickness at constant strength and is therefore a promising technology for the production of lightweight and energy-efficient automobiles. The manganese-boron steel 22MnB5 have been implemented in sheet press hardening owing to their excellent hot formability, high hardenability, and good temperability even at low cooling rates. However, press-hardened components have shown poor ductility and cracking at relatively small strains. A possible solution to this problem is a selective increase of steel sheet ductility by press hardening process design in areas where the component is required to deform plastically during crash tests. To this end, process designers require information about microstructure and mechanical properties as a function of the wide spectrum of cooling rates and sequences and austenitizing treatment conditions that can be encountered in production environments. In the present work, a Continuous Cooling Transformation (CCT) diagram with corresponding material properties of sheet steel 22MnB5 was determined for a wide spectrum of cooling rates. Heating and cooling programs were conducted in a quenching dilatometer. Motivated by the importance of residual elasticity in crash test performance, this property was measured using a micro-bending test and the results were integrated into the CCT diagrams to complement the hardness testing results. This information is essential for the process design of press hardening of sheet components with gradient material properties.

  18. Investigation of material property influenced stoichiometric deviations as evidenced during UV laser-assisted atom probe tomography in fluorite oxides

    NASA Astrophysics Data System (ADS)

    Valderrama, Billy; Henderson, Hunter B.; Yablinsky, Clarissa A.; Gan, Jian; Allen, Todd R.; Manuel, Michele V.

    2015-09-01

    Oxide materials are used in numerous applications such as thermal barrier coatings, nuclear fuels, and electrical conductors and sensors, all applications where nanometer-scale stoichiometric changes can affect functional properties. Atom probe tomography can be used to characterize the precise chemical distribution of individual species and spatially quantify the oxygen to metal ratio at the nanometer scale. However, atom probe analysis of oxides can be accompanied by measurement artifacts caused by laser-material interactions. In this investigation, two technologically relevant oxide materials with the same crystal structure and an anion to cation ratio of 2.00, pure cerium oxide (CeO2) and uranium oxide (UO2) are studied. It was determined that electronic structure, optical properties, heat transfer properties, and oxide stability strongly affect their evaporation behavior, thus altering their measured stoichiometry, with thermal conductance and thermodynamic stability being strong factors.

  19. Properties and processing of nanocrystalline materials. Quarterly report

    SciTech Connect

    Valiev, R.Z.

    1996-01-22

    The present Report completes the investigations in the frame of the project for the first year. It is important to estimate our achievements in the investigation of properties of nanocrystalline materials obtained by severe plastic deformation and their production. We think that the main results obtained can be summarized as follows: (1) We performed an improvement of the die-set for equal channel (ECA) pressing and torsion under high pressure with the aim to increase dimensions of the samples produced and to conduct processing of low ductile materials. (2) It was established that in pure metals severe plastic deformation led to the formation of an ultra fine-grained structure with a mean grain size of 100-200 nm, while in alloys due to severe plastic deformation and/or special methods of treatment (a decrease in the temperature of deformation, an increase of the pressure applied etc.) the grain size could be decreased down to a few tens of manometers.

  20. Development and mechanical properties of structural materials from lunar simulants

    NASA Technical Reports Server (NTRS)

    Desai, Chandra S.; Girdner, K.; Saadatmanesh, H.; Allen, T.

    1991-01-01

    Development of the technologies for manufacture of structural and construction materials on the Moon, utilizing local lunar soil (regolith), without the use of water, is an important element for habitats and explorations in space. Here, it is vital that the mechanical behavior such as strength and flexural properties, fracture toughness, ductility and deformation characteristics be defined toward establishment of the ranges of engineering applications of the materials developed. The objective is to describe the research results in two areas for the above goal: (1) liquefaction of lunar simulant (at about 100 C) with different additives (fibers, powders, etc.); and (2) development and use of a new triaxial test device in which lunar simulants are first compressed under cycles of loading, and then tested with different vacuums and initial confining or in situ stress.

  1. Design of materials configurations for enhanced phononic and electronic properties

    NASA Astrophysics Data System (ADS)

    Daraio, Chiara

    The discovery of novel nonlinear dynamic and electronic phenomena is presented for the specific cases of granular materials and carbon nanotubes. This research was conducted for designing and constructing optimized macro-, micro- and nano-scale structural configurations of materials, and for studying their phononic and electronic behavior. Variation of composite arrangements of granular elements with different elastic properties in a linear chain-of-sphere, Y-junction or 3-D configurations led to a variety of novel phononic phenomena and interesting physical properties, which can be potentially useful for security, communications, mechanical and biomedical engineering applications. Mechanical and electronic properties of carbon nanotubes with different atomic arrangements and microstructures were also investigated. Electronic properties of Y-junction configured carbon nanotubes exhibit an exciting transistor switch behavior which is not seen in linear configuration nanotubes. Strongly nonlinear materials were designed and fabricated using novel and innovative concepts. Due to their unique strongly nonlinear and anisotropic nature, novel wave phenomena have been discovered. Specifically, violations of Snell's law were detected and a new mechanism of wave interaction with interfaces between NTPCs (Nonlinear Tunable Phononic Crystals) was established. Polymer-based systems were tested for the first time, and the tunability of the solitary waves speed was demonstrated. New materials with transformed signal propagation speed in the manageable range of 10-100 m/s and signal amplitude typical for audible speech have been developed. The enhancing of the mitigation of solitary and shock waves in 1-D chains were demonstrated and a new protective medium was designed for practical applications. 1-D, 2-D and 3-D strongly nonlinear system have been investigated providing a broad impact on the whole area of strongly nonlinear wave dynamics and creating experimental basis for new

  2. Measurement of Thermal Properties of Biosourced Building Materials

    NASA Astrophysics Data System (ADS)

    Pierre, Thomas; Colinart, Thibaut; Glouannec, Patrick

    2014-10-01

    This paper presents both experimental and theoretical works concerning the evaluation of the thermal conductivity and thermal diffusivity of hemp concrete. Experimental measurements of thermal properties are performed using a hot-strip technique for temperatures ranging from 3 to 30 and relative humidities ranging from 0 % to 95 %, thus creating a large database for this material. These experimental thermal conductivities are then compared with the results from the Krischer theoretical predictive model. The comparison shows good agreement, and a predictive analytical relation between the hemp concrete thermal conductivity, temperature, and relative humidity is determined.

  3. Distributional properties of stochastic shortest paths for smuggled nuclear material

    SciTech Connect

    Cuellar, Leticia; Pan, Feng; Roach, Fred; Saeger, Kevin J

    2011-01-05

    The shortest path problem on a network with fixed weights is a well studied problem with applications to many diverse areas such as transportation and telecommunications. We are particularly interested in the scenario where a nuclear material smuggler tries to succesfully reach herlhis target by identifying the most likely path to the target. The identification of the path relies on reliabilities (weights) associated with each link and node in a multi-modal transportation network. In order to account for the adversary's uncertainty and to perform sensitivity analysis we introduce random reliabilities. We perform some controlled experiments on the grid and present the distributional properties of the resulting stochastic shortest paths.

  4. Investigating the Size Dependent Material Properties of Nanoceria

    NASA Astrophysics Data System (ADS)

    Alam, Bushra B.

    Nanoceria is widely being investigated for applications as support materials for fuel cell catalysts, free radical scavengers, and as chemical and mechanical abrasives due to its high antioxidant capacity and its oxygen buffering capacity. This antioxidant or oxygen buffering capacity has been reported to be highly size dependent and related to its redox properties. However, the quantification of this antioxidant capacity has not been well defined or understood and has been often been carried out using colorimetric assays which do not directly correlate to ceria nanoparticle properties. Fabrication rules for developing materials with optimal antioxidant/oxygen buffering capacities are not yet defined and one of the limitations has been the challenge of obtaining quantitative measurements of the antioxidant properties. In this work, we create our own library of ceria nanoparticles of various size distributions by two synthesis methods: sol-gel peroxo and thermal decomposition/calcination and annealing in open atmosphere at three different temperatures. The synthesis methods and conditions produce characteristic sizes and morphologies of ceria nanoparticles. Qualitative and quantitative approaches are used for characterization and to predict reactivity. Qualitative approaches include Brunauer-Emmett-Teller (BET) surface area measurements and Raman analysis while quantitative approaches include a combination of powder X-ray diffraction (XRD) Rietveld analysis, Transmission Electron Microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) to measure crystallite sizes, lattice parameters, oxygen site occupancies, and the relative abundance of Ce(III) ions in a nanoceria sample. These methods are discussed in detail in addition to their limitations and challenges. These methods are used to predict nanocrystalline or bulk-like behavior of ceria nanoparticles. The investigation of the material properties is also extended to test the redox properties of ceria

  5. Research on the icephobic properties of fluoropolymer-based materials

    NASA Astrophysics Data System (ADS)

    Yang, Shuqing; Xia, Qiang; Zhu, Lin; Xue, Jian; Wang, Qingjun; Chen, Qing-min

    2011-03-01

    Fluoropolymer, because of the extremely low surface energy, could be non-stick to water and thus could be a good candidate as anti-icing materials. In this paper, the icephobic properties of a series of fluoropolymer materials including pristine PTFE plates (P-PTFE), sandblasted PTFE plates (SB-PTFE), two PTFE coatings (SNF-1 and SNF-CO1), a fluorinated room-temperature vulcanized silicone rubber coating (F-RTV) and a fluorinated polyurethane coating (F-PU) have been investigated by using SEM, XPS, ice adhesion strength (tensile and shear) tests, and static and dynamic water contact angle analysis. Results show that the fluoropolymer material with a smooth surface can significantly reduce ice adhesion strength but do not show obvious effect in reducing ice accretion at -8 °C. Fluoropolymers with sub-micron surface structures can improve the hydrophobicity at normal temperature. It leads to an efficient reduction in the ice accretion on the surface at -8 °C, due to the superhydrophobicity of the materials. But the hydrophobicity of this surface descends at a low temperature with high humidity. Consequently, once ice layer formed on the surface, the ice adhesion strength enhanced rapidly due to the existence of the sub-micron structures. Ice adhesion strength of fluoropolymers is highly correlated to CA reduction observed when the temperature was changed from 20 °C to -8 °C. This property is associated with the submicron structure on the surface, which allows water condensed in the interspace between the sub-micron protrudes at a low temperature, and leads to a reduced contact angle, as well as a significantly increased ice adhesion strength.

  6. Cryogenic Properties of Aluminum-Beryllium and Beryllium Materials

    NASA Technical Reports Server (NTRS)

    Gamwell, Wayne R.; McGill, Preston B.

    2003-01-01

    Ultimate tensile strength, yield strength, and elongation were obtained for the aluminum- beryllium alloy, AlBeMetl62 (38%Al-62%Be), at cryogenic (-195.5 C (-32O F) and (- 252.8 C) (-423 F)) temperatures, and for an optical grade beryllium, O-30H (99%Be), at -252.8 C. AlBeMet162 material was purchased to the requirements of SAE- AMs7912, "Aluminum-Beryllium Alloy, Extrusions". O-30H material was purchased to the requirements of Brush Wellman Inc. specification O-30H Optical Grade Beryllium. The ultimate tensile and yield strengths for extruded AlBeMet162 material increased with decreasing temperature, and the percent elongation decreased with decreasing temperature. Design properties for the ultimate tensile strength, yield strength, and percent elongation for extruded AlBeMetl62 were generated. It was not possible to distinguish a difference in the room and cryogenic ultimate strength for the hot isostatically pressed (HIP'ed) O-30H material. The O-30H elongation decreased with decreasing temperature.

  7. Cryogenic Properties of Aluminum Beryllium and Beryllium Materials

    NASA Technical Reports Server (NTRS)

    Gamwell, Wayne R.; McGill, Preston B.

    2003-01-01

    Ultimate tensile strength, yield strength, and elongation were obtained for the aluminum-beryllium alloy, AlBeMetl62 (38%Al-62%Be), at cryogenic (-195.5 C (-320 F) and (-252.8 C) (-423 F)) temperatures, and for an optical grade beryllium, O-30H (99%Be), at -252.8 C. AlBeMetl62 material was purchased to the requirements of SAE-AMS7912, "Aluminum-Beryllium Alloy, Extrusions." O-30H material was purchased to the requirements of Brush Wellman Inc. specification O-30H Optical Grade Beryllium. The ultimate tensile and yield strengths for extruded AlBeMetl62 material increased with decreasing temperature, and the percent elongation decreased with decreasing temperature. Design properties for the ultimate tensile strength, yield strength, and percent elongation for extruded AlBeMetl62 were generated. It was not possible to distinguish a difference in the room and cryogenic ultimate strength for the hot isostatically pressed (HIP'ed) O-30H material. The O30H elongation decreased with decreasing temperature.

  8. Mechanisms Responsible for Microwave Properties in High Performance Dielectric Materials

    NASA Astrophysics Data System (ADS)

    Zhang, Shengke

    Microwave properties of low-loss commercial dielectric materials are optimized by adding transition-metal dopants or alloying agents (i.e. Ni, Co, Mn) to tune the temperature coefficient of resonant frequency (tau f) to zero. This occurs as a result of the temperature dependence of dielectric constant offsetting the thermal expansion. At cryogenic temperatures, the microwave loss in these dielectric materials is dominated by electron paramagnetic resonance (EPR) loss, which results from the spin-excitations of d-shell electron spins in exchange-coupled clusters. We show that the origin of the observed magnetically-induced shifts in the dielectric resonator frequency originates from the same mechanism, as described by the Kramers-Kronig relations. The temperature coefficient of resonator frequency, tauf, is related to three material parameters according to the equation, tau f = - (½ tauepsilon + ½ taumu + alphaL), where tauepsilon, taumu , and alphaL are the temperature coefficient of dielectric constant, magnetic permeability, and lattice constant, respectively. Each of these parameters for dielectric materials of interest are measured experimentally. These results, in combination with density functional simulations, developed a much improved understanding of the fundamental mechanisms responsible for tau f. The same experimental methods have been used to characterize in-situ the physical nature and concentration of performance-degrading point defects in the dielectrics of superconducting planar microwave resonators.

  9. Development and mechanical properties of construction materials from lunar simulant

    NASA Technical Reports Server (NTRS)

    Desai, Chandra S.

    1992-01-01

    Development of versatile engineering materials from locally available materials in space is an important step toward the establishment of outposts on the Moon and Mars. Development of the technologies for manufacture of structural and construction materials on the Moon, utilizing local lunar soil (regolith), without the use of water, is an important element for habitats and explorations in space. It is also vital that the mechanical behavior such as strength and tensile, flexural properties, fracture toughness, ductility, and deformation characteristics are defined toward establishment of the ranges of engineering applications of the materials developed. The objectives include two areas: (1) thermal 'liquefaction' of lunar simulant (at about 1100 C) with different additives (fibers, powders, etc.), and (2) development and use of a new triaxial test device in which lunar simulants are first compacted under cycles of loading, and then tested with different vacuums and initial confining or in situ stress. Details of the development of intermediate ceramic composites (ICC) and testing for their flexural and compression characteristics were described in various reports and papers. The subject of behavior of compacted simulant under vacuum was described in previous progress reports and publications; since the presently available device allows vacuum levels up to only 10(exp -4) torr, it is recommended that a vacuum pump that can allow higher levels of vacuum be utilized for further investigation.

  10. Development and mechanical properties of structural materials from lunar simulant

    NASA Technical Reports Server (NTRS)

    Desai, Chandra S.

    1991-01-01

    Development of versatile engineering materials from locally available materials in space is an important step toward establishment of outposts such as on the moon and Mars. Here development of the technologies for manufacture of structural and construction materials on the moon, utilizing local lunar soil (regolith), without the use of water, is an important element for habitats and explorations in space. It is also vital that the mechanical behavior such as strength and flexural properties, fracture toughness, ductility, and deformation characteristics are defined toward establishment of the ranges of engineering applications of the materials developed. The objectives include two areas: (1) thermal liquefaction of lunar simulant (at about 1100 C) with different additives (fibers, powders, etc.); and (2) development and use of a traxial test device in which lunar simulants are first compacted under cycles of loading, and then tested with different vacuums and initial confining or insitu stress. The second area was described in previous progress reports and publications; since the presently available device allows vacuum levels up to only 10(exp -4) torr, it is recommended that a vacuum pump that can allow higher levels of vacuum is acquired.

  11. Effects of solvent casting copolymer materials as related to mechanical properties.

    PubMed

    Bagrodia, S; Wilkes, G L

    1976-01-01

    Using a well characterized series of styrene butadiene triblock copolymers a systematic study was carried out to determine the influence of casting solvent, used for film preparation, on the final mechanical properties. The results clearly indicate that in the range of styrene contents of 30-40 mol %, the modulus behavior is greatly affected as the solubility parameter of the casting solvent, delta, is varied. Specifically, the modulus increases as delta increases to the value of polystyrene. At lower or higher styrene content, the properties are influenced but to a much lesser degree. Other mechanical properties measured were yield stress and breaking stress. The ramifications of these data are discussed in light of preparing prosthetic material via solvent casting. PMID:1249085

  12. Preparation, tribological properties and biocompatibility of fluorinated graphene/ultrahigh molecular weight polyethylene composite materials

    NASA Astrophysics Data System (ADS)

    Xu, L.; Zheng, Y.; Yan, Z.; Zhang, W.; Shi, J.; Zhou, F.; Zhang, X.; Wang, J.; Zhang, J.; Liu, B.

    2016-05-01

    Fluorinated graphene (FG)/ultra-high molecular weight polyethylene (UHMWPE) composites were successfully prepared by ultrasonic dispersion and liquid thermoforming method. The mechanical and tribological properties of pure UHMWPE and FG/UHMWPE composites were investigated using micro-hardness tester and high-speed reciprocating friction tester. The results showed that: adding FG could not only increase the micro-hardness of the composites, but also decrease the wear volume of the composite significantly. The friction coefficients of the composites were also reduced with the increasing of FG content. In addition, the MC3T3-E1 cells adhered and grew well on the surface of the FG/UHMWPE composites as observed by SEM and fluorescence microscope, indicating the addition of FG did not affect the morphology and activity of the cells. The FG/UHMWPE composites exhibited excellent mechanical properties, tribological properties and biocompatibility, which could be used as the potential artificial joint replacement material.

  13. Water and moisture susceptibility of chitosan and paper-based materials: structure-property relationships.

    PubMed

    Bordenave, N; Grelier, S; Pichavant, F; Coma, V

    2007-11-14

    Environmentally friendly and potentially bioactive food packaging based on chitosan-coated papers were elaborated. The morphology and the microstructure of these new materials were characterized by infrared spectroscopy and scanning electron microscopy. These observations suggested that the chitosan penetrated deeply into the paper, embedding the cellulose fibers, instead of forming a layer as expected. Through the barrier properties against moisture, the liquid water sensitivity, and NMR-relaxometry measurements, the water interactions were evaluated on the chitosan films and the chitosan-coated papers. They revealed that the coating by a chitosan film forming solution improved the paper moisture barrier properties but the surface hydrophilicity remained high. Relaxometry studies showed that, due to its hydrophilic character, chitosan controlled the interaction with water, despite the very low amount of deposit. On the other hand, the mechanical properties of papers were unmodified by the chitosan coating, which did not fundamentally affect the solid structure of the papers. PMID:17953443

  14. Mechanical properties of Skylab thermal shield materials after prolonged ultraviolet irradiation

    NASA Technical Reports Server (NTRS)

    Haehner, C. L.; Staugaitis, C. L.

    1974-01-01

    In response to an emergency request, the mechanical properties of two complex laminate materials, used as thermal shields on the Skylab spacecraft, were investigated. Concern over the prolonged use of these materials in the space environment prompted this investigation. Shields made of both of these materials, popularly called the parasol and the sail types, were taken to the Skylab spacecraft by the original Skylab astronauts. Both were used to restore thermal control after the original control surfaces were damaged during launch. During the tests the tensile properties were measured at anticipated service temperature and after prolonged exposure to increasing degrees of ultraviolet radiation at intensities approaching two solar constants. Some samples received exposures equivalent to 2,350 hours. The performance and degradation of the two materials are presented in terms of orientation, vacuum, and degree of irradiation. In general, the 75-micron (3-mil) parasol laminate showed a decrease in tensile properties as a function of exposure time, while the 200-micron (8-mil) sail laminate was little affected by exposure to the ultraviolet radiation.

  15. Effect of disinfection of custom tray materials on adhesive properties of several impression material systems.

    PubMed

    Thompson, G A; Vermilyea, S G; Agar, J R

    1994-12-01

    The effects of impression tray disinfection procedures on the bond strength of impression-material adhesives to two types of resin trays were evaluated with a tensile test. Autopolymerizing acrylic resin and a visible light-curing resin were formed into one-half inch cubes. A screw eye was attached to each cube before polymerization. Perforated trays were fabricated with stops to maintain an even one-eighth inch of impression material over the resin block. Hooks on the opposite side permitted attachment of the metal plate to a mechanical testing machine. Before adhesive was applied, one third of the resin specimens were immersed in a 1:213 iodophor solution; one third in a 10% sodium hypochlorite solution, and one third were kept in the "as fabricated" condition. Polysulfide, polyether, and polyvinyl siloxane impression material-adhesive systems were evaluated. The resin-impression material-metal plate couples were attached to a mechanical testing machine and tensile forces were applied at a separation rate of 5 inches per minute. Mean values for adhesive strength ranged from 3.49 kg/cm2 for the autopolymerizing acrylic resin/iodophor/polyether combination to 10.55 kg/cm2 for the autopolymerizing acrylic resin/untreated/polyvinyl siloxane combination. Differences were detected among materials and disinfecting procedure. Clinically, disinfection of resin trays may adversely affect retention of the impression material to the tray. PMID:7853264

  16. Structural factors affecting lithium transport in lithium-excess layered cathode materials

    NASA Astrophysics Data System (ADS)

    Fell, Christopher R.

    Lithium ion batteries have drawn significant attention as the principle energy storage device powering today's mobile electronic equipment. Despite the increased usage, the performance of current lithium ion battery technology falls short of the requirements needed for large format applications such as electric vehicles. The layered lithium-excess oxide compounds Li[NixLi1/3-2x/3Mn2/3-x/3]O2 are of interest as a new generation of cathode materials for high energy density lithium ion batteries. Efforts to achieve a better understanding of the electrochemistry of lithium-excess materials require the connection of crystal structure to electrochemical properties. In this dissertation, a combination of advanced characterization techniques was used as a tool to understand the intercalation mechanism of the layered lithium-excess transition metal oxide Li[NixLi1/3-2x/3Mn 2/3-x/3]O2. The research identified that synthesis influences the structure of the material specifically the surface of the particles. The formation of a hydroxide rich surface film decreases the electrochemical performance. Post synthesis modifications including high pressure and high temperature leads to the formation of a second layered phase in the bulk; however, the treated samples display good electrochemical properties. This result underlines the flexibility of the structure of Li[NixLi1/3-2x/3Mn 2/3-x/3]O2, a feature uncommon to other layered transition metal oxides. Surface characterization of the layered lithium-excess cathodes following electrochemical cycling revealed the formation of a new surface phase 1 to 5 nm thick as well as insight to the complex cation rearrangement process and phase transformation. This part of the research identified that significant changes occurred during electrochemical cycling; however did not identify when the transformations occurred. Investigation using in situ techniques during the first electrochemical cycle shows that the structure undergoes irreversible

  17. Obesity-related changes in bone structural and material properties in hyperphagic OLETF rats and protection by voluntary wheel running

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We conducted a study to examine how the development of obesity and the associated insulin resistance affect bone structural and material properties, and bone formation and resorption markers in the Otsuka Long-Evans Tokushima Fatty (OLETF) rat model. This was a 36-week study of sedentary, hyperphag...

  18. Effect of sterilization on structural and material properties of 3-D silk fibroin scaffolds.

    PubMed

    Hofmann, Sandra; Stok, Kathryn S; Kohler, Thomas; Meinel, Anne J; Müller, Ralph

    2014-01-01

    The development of porous scaffolds for tissue engineering applications requires the careful choice of properties, as these influence cell adhesion, proliferation and differentiation. Sterilization of scaffolds is a prerequisite for in vitro culture as well as for subsequent in vivo implantation. The variety of methods used to provide sterility is as diverse as the possible effects they can have on the structural and material properties of the three-dimensional (3-D) porous structure, especially in polymeric or proteinous scaffold materials. Silk fibroin (SF) has previously been demonstrated to offer exceptional benefits over conventional synthetic and natural biomaterials in generating scaffolds for tissue replacements. This study sought to determine the effect of sterilization methods, such as autoclaving, heat-, ethylene oxide-, ethanol- or antibiotic-antimycotic treatment, on porous 3-D SF scaffolds. In terms of scaffold morphology, topography, crystallinity and short-term cell viability, the different sterilization methods showed only few effects. Nevertheless, mechanical properties were significantly decreased by a factor of two by all methods except for dry autoclaving, which seemed not to affect mechanical properties compared to the native control group. These data suggest that SF scaffolds are in general highly resistant to various sterilization treatments. Nevertheless, care should be taken if initial mechanical properties are of interest. PMID:24013025

  19. Thermophysical properties study of micro/nanoscale materials

    NASA Astrophysics Data System (ADS)

    Feng, Xuhui

    Thermal transport in low-dimensional structure has attracted tremendous attentions because micro/nanoscale materials play crucial roles in advancing micro/nanoelectronics industry. The thermal properties are essential for understanding of the energy conversion and thermal management. To better investigate micro/nanoscale materials and characterize the thermal transport, pulse laser-assisted thermal relaxation 2 (PLTR2) and transient electrothermal (TET) are both employed to determine thermal property of various forms of materials, including thin films and nanowires. As conducting polymer, Poly(3-hexylthiophene) (P3HT) thin film is studied to understand its thermal properties variation with P3HT weight percentage. 4 P3HT solutions of different weight percentages are compounded to fabricate thin films using spin-coating technique. Experimental results indicate that weight percentage exhibits impact on thermophysical properties. When percentage changes from 2% to 7%, thermal conductivity varies from 1.29 to 1.67 W/m·K and thermal diffusivity decreases from 10-6 to 5×10-7 m2/s. Moreover, PLTR2 technique is applied to characterize the three-dimensional anisotropic thermal properties in spin-coated P3HT thin films. Raman spectra verify that the thin films embrace partially orientated P3HT molecular chains, leading to anisotropic thermal transport. Among all three directions, lowest thermal property is observed along out-of-plane direction. For in-plane characterization, anisotropic ratio is around 2 to 3, indicating that the orientation of the molecular chains has strong impact on the thermal transport along different directions. Titanium dioxide (TiO2) thin film is synthesized by electrospinning features porous structure composed by TiO2 nanowires with random orientations. The porous structure caused significant degradation of thermal properties. Effective thermal diffusivity, conductivity, and density of the films are 1.35˜3.52 × 10-6 m2/s, 0.06˜0.36 W/m·K, and

  20. Elucidating the role of interfacial materials properties in microfluidic packages.

    SciTech Connect

    Edwards, Thayne L.

    2013-01-01

    The purpose of this work was to discover a method to investigate the properties of interfaces as described by a numerical physical model. The model used was adopted from literature and applied to a commercially available multiphysics software package. By doing this the internal properties of simple structures could be elucidated and then readily applied to more complex structures such as valves and pumps in laminate microfluidic structures. A numerical finite element multi-scale model of a cohesive interface comprised of heterogeneous material properties was used to elucidate irreversible damage from applied strain energy. An unknown internal state variable was applied to characterize the damage process. Using a constrained blister test, this unknown internal state variable could be determined for an adherend/adhesive/adherend body. This is particularly interesting for laminate systems with microfluidic and microstructures contained within the body. A laminate structure was designed and fabricated that could accommodate a variety of binary systems joined using nearly any technique such as adhesive, welding (solvent, laser, ultrasonic, RF, etc.), or thermal. The adhesive method was the most successful and easy to implement but also one of the more difficult to understand, especially over long periods of time. Welding methods are meant to achieve a bond that is similar to bulk properties and so are easier to predict. However, methods of welding often produce defects in the bonds.. Examples of the test structures used to elucidate the internal properties of the model were shown and demonstrated. The real life examples used this research to improve upon current designs and aided in creating complex structures for sensor and other applications.

  1. Positive and negative affect schedule: psychometric properties for the Brazilian Portuguese version.

    PubMed

    Pires, Pedro; Filgueiras, Alberto; Ribas, Rodolfo; Santana, Cristina

    2013-01-01

    This study is about the validity and item analysis for the Positive and Negative Affect Schedule (PANAS), respectively through the Exploratory Factor Analysis (principal components method) and the Partial Credit Model (PCM). The scale has been largely used in areas ranging from clinical to social psychology since its release in 1988 by Watson, Clark, and Tellegen. In order to assess validity and item properties (Item Response Theory paradigm), this is study administered PANAS to 354 respondents, 115 male and 239 female subjects, with an average age of 29.5 (SD = 10,18). The results show PANAS's excellent psychometric properties, with consistent dimensions and reliable item functioning, considering the Rasch measurement paradigm expressed in the PCM as an Item Response Theory model for polytomous data. The study considers important cultural issues and the results support more cautious translations for scales as well as further studies concerned with cross-cultural differences on the perception of affect states. PMID:24230921

  2. Analysis of material properties for MEMS using interferometric measurements

    NASA Astrophysics Data System (ADS)

    O'Mahony, Conor; Hill, Martin; Mathewson, Alan

    2003-03-01

    As the scope and depth of research into microelectromechanical systems increases, the issue of mechanical characterisation has emerged as a major consideration in device design. It is now common to include a set of test structures on a MEMS wafer for extraction of thin film material properties (in particular, residual stress and Young's modulus). These structures usually consist of micromachined beams and strain gauges, and measurement techniques include tensile testing, electromechanical characterisation, SEM imaging, and Raman spectroscopy. However, some of these tests are destructive and difficult to carry out at wafer scale. This work uses electrostatic actuation to pull fixed-fixed beams towards the substrate, and a white-light interferometer to record the beam deflection profile. Finite-element simulation software is employed to model this deflection, and to estimate the material properties which minimise the difference between the measured and simulated profiles. The test is non-destructive, suitable for wafer-level characterisation, and the structures involved require less die space than other methods. We have developed a 1.5mm surface micromachining process for the fabrication of composite and monolayer structures with applications in relay switching, optical imaging and radio-frequency components. This work presents results obtained using interferometric analysis for both monolayer (titanium) and composite (SiOx - metal) thin films fabricated with this process.

  3. Photoacoustic characterization of the mechanical properties of thin film materials

    NASA Astrophysics Data System (ADS)

    Zhang, Feifei; Krishnaswamy, Sridhar; Fei, Dong; Rebinsky, Douglas A.

    2005-05-01

    Two high frequency photoacoustic techniques were applied to investigate the mechanical properties of two sets of thin film materials in this work. Broadband photoacoustic guided-wave method was used to measure the guided-wave phase velocity dispersion curves of nano-structured diamond-like carbon hard coatings. The experimental velocity spectra were analyzed by a nonlinear optimization approach in conjunction with a multi-layer wave-propagation model. The derived Young"s moduli using the broadband photoacoustic technique were compared with line-focus acoustic microscopy and nano-indentation tests and good quantitative agreement is found. In a second set of experiments, ultra-thin two-layer aluminum and silicon nitride thin film materials were tested using the femtosecond transient pump-probe method using high frequency bulk waves generated by the ultra-fast laser pulses. The measured moduli of silicon nitride thin layers are in the range of 270 - 340 GPa. Photoacoustic methods are shown to be suitable for in-situ and non-destructive evaluation of the mechanical properties of thin films.

  4. Electrochromic & magnetic properties of electrode materials for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Zheng-Fei, Guo; Kun, Pan; Xue-Jin, Wang

    2016-01-01

    Progress in electrochromic lithium ion batteries (LIBs) is reviewed, highlighting advances and possible research directions. Methods for using the LIB electrode materials’ magnetic properties are also described, using several examples. Li4Ti5O12 (LTO) film is discussed as an electrochromic material and insertion compound. The opto-electrical properties of the LTO film have been characterized by electrical measurements and UV-Vis spectra. A prototype bi-functional electrochromic LIB, incorporating LTO as both electrochromic layer and anode, has also been characterized by charge- discharge measurements and UV-Vis transmittance. The results show that the bi-functional electrochromic LIB prototype works well. Magnetic measurement has proven to be a powerful tool to evaluate the quality of electrode materials. We introduce briefly the magnetism of solids in general, and then discuss the magnetic characteristics of layered oxides, spinel oxides, olivine phosphate LiFePO4, and Nasicon-type Li3Fe2(PO4)3. We also discuss what kind of impurities can be detected, which will guide us to fabricate high quality films and high performance devices. Project supported by the National High Technology Research and Development Program of China (Grant No. 2015AA034201) and the Chinese Universities Scientific Fund (Grant No. 2015LX002).

  5. Material Properties of Three Candidate Elastomers for Space Seals Applications

    NASA Technical Reports Server (NTRS)

    Bastrzyk, Marta B.; Daniels, Christopher C.; Oswald, Jay J.; Dunlap, Patrick H., Jr.; Steinetz, Bruce M.

    2010-01-01

    A next-generation docking system is being developed by the National Aeronautics and Space Administration (NASA) to support Constellation Space Exploration Missions to low Earth orbit (LEO), to the Moon, and to Mars. A number of investigations were carried out to quantify the properties of candidate elastomer materials for use in the main interface seal of the Low Impact Docking System (LIDS). This seal forms the gas pressure seal between two mating spacecraft. Three candidate silicone elastomer compounds were examined: Esterline ELA-SA-401, Parker Hannifin S0383-70, and Parker Hannifin S0899-50. All three materials were characterized as low-outgassing compounds, per ASTM E595, so as to minimize the contamination of optical and solar array systems. Important seal properties such as outgas levels, durometer, tensile strength, elongation to failure, glass transition temperature, permeability, compression set, Yeoh strain energy coefficients, coefficients of friction, coefficients of thermal expansion, thermal conductivity and diffusivity were measured and are reported herein.

  6. Structure and Thermoelectric Properties of Zinc Oxide Based Materials

    NASA Astrophysics Data System (ADS)

    Liang, Xin

    The present dissertation investigates the relationship between the structure and thermoelectric properties of ZnO based materials, with a focus on trivalent element doping on engineering the microstructure and altering the electrical and thermal transport properties. Within the solubility range, the addition of trivalent elements, such as In3+, Fe 3+ and Ga3+, is observed to increase the electrical conductivity of ZnO and decrease the thermal conductivity. As the solubility is exceeded, the consequent structure and thermoelectric properties varies with dopant species. The ZnO-In2O3 binary system, which we have chosen as one of the model systems, is of particular interests as it contains a variety of phase equilibria and microstructures. The In2O3(ZnO)k superlattice structures, which form as the indium solubility is reached, are observed to strongly scatter phonons while relatively permissive to electrons, resulting in a low thermal conductivity of about 2 W/mK and improved electrical conductivity. The thermal (Kapitza) resistance of In2O3(ZnO)k superlattice interfaces is found to be 5.0 +/- 0.6 x 10-10 m 2K/W by fitting the modified Klemens-Callaway's thermal conductivity model to the experimental data. Across the phase diagram, the materials behave as n-type free-electron semiconductors at high temperatures. An effective medium approximation model is for the first time successfully tested on the thermoelectrics of two-phase regions. Both Fe2O3-ZnO and Ga2O3-ZnO binary systems are also investigated. In the Fe doped ZnO system, a highly Fe concentrated ZnO solid solution phase as well as the significant grain refinement are observed after high temperature annealing. The Ga2O 3(ZnO)9 homologous superlattices in Ga2O 3-ZnO system is also found to strongly scatter phonons and induces a drastic reduction in thermal conductivity. Thermal conductivity, as one of the key factors in thermoelectrics, is highly sensitive to material defects. In this dissertation, I also

  7. Effects of fault movement and material properties on deformation and stress fields of Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Zheng, Yong; Xiong, Xiong; Chen, Yong; Shan, Bin

    2011-04-01

    We compare the factors which affect the movement of Tibetan Plateau by building three types of finite element models: an elastic materials (M-EC), a continuous model composed by non-linear materials (M-PC), and an elastic model with discontinuous fault movements (M-ET). Both in M-ET and M-EC, the materials in Qiangtang and Lhasa block are elastic, and in M-ET, discontinuous movement of faults is considered for evaluating the effects of strike-slip faults. In model M-PC Druker-Prager plastic materials are used in Qiangtang and Lhasa block. Comparisons of the numerical simulation and the GPS observations show following characteristics: (1) Under present tectonic environment, short-term deformation of Tibetan Plateau can be simulated well by elastic models; (2) Discontinuous fault activities increase the lateral extrusion of the eastern part of Tibetan Plateau, reduce the stress field level in Qiangtang, Tarim and Qaidam blocks and strengthen the E-W extensional force in the east and the west parts of Qiangtang block; (3) Properties of plastic materials reduce the total stress field and the E-W extensional force, thus, the normal fault earthquakes in southern Tibet is mainly owed to the effect of active fault movement. Based on the numerical simulations we speculate that faults movement may play a more important role on the kinematic pattern of Tibetan Plateau than bulk properties.

  8. Effects of storage media on physical properties of selected tooth coloured restorative materials.

    PubMed

    Sadaghiani, Leili; Adusei, Gabriel; Rees, Jeremy

    2009-09-01

    It is known that storage media can affect the physical properties of some restorative dental materials. The purpose of this laboratory study was to investigate the possible effects of storage media on physical properties of a conventional glass-ionomer, a resin modified glass ionomer and a compomer. Specimens of the restorative materials in the study (FujiII LC, FujiIX and Dyract EXTRA) were prepared. The specimens were stored in either water or artificial saliva with or without exposure to Listerine. The compressive and diametral tensile strength and Vickers hardness of these materials were tested at 24 hours, 1 week, 4 weeks and 12 weeks. Compressive and diametral tensile strength for FujiII LC and Fuji IX had increased at 12 weeks. A decrease was observed for Dyract EXTRA in the same period. No significant differences were observed between the storage media (P > 0.01). Vickers hardness values fluctuated during the testing period, with a pattern being consistent for each material. Storage of materials investigated for the period in this study resulted in superior compressive and diametral tensile strength for Fuji II LC and FujiIX. The opposite was true for Dyract EXTRA. Effects of time were found to be more pronounced than the media (P < 0.01). PMID:19839187

  9. Physical property comparison of 11 soft denture lining materials as a function of accelerated aging.

    PubMed

    Dootz, E R; Koran, A; Craig, R G

    1993-01-01

    Soft denture-lining materials are an important treatment option for patients who have chronic soreness associated with dental prostheses. Three distinctly different types of materials are generally used. These are plasticized polymers or copolymers, silicones, or polyphosphazene fluoroelastomer. The acceptance of these materials by patients and dentists is variable. The objective of this study is to compare the tensile strength, percent elongation, hardness, tear strength, and tear energy of eight plasticized polymers or copolymers, two silicones, and one polyphosphazene fluoroelastomer. Tests were run at 24 hours after specimen preparation and repeated after 900 hours of accelerated aging in a Weather-Ometer device. The data indicated a wide range of physical properties for soft denture-lining materials and showed that accelerated aging dramatically affected the physical and mechanical properties of many of the elastomers. No soft denture liner proved to be superior to all others. The data obtained should provide clinicians with useful information for selecting soft denture lining materials for patients. PMID:8455156

  10. Hydrodynamics and Material Properties Experiments Using Pulsed Power Techniques*

    NASA Astrophysics Data System (ADS)

    Reinovsky, Robert; Trainor, R. James

    1999-06-01

    Within the last few years a new approach for exploring dynamic material properties and advanced hydrodynamics at extreme conditions has joined the traditional techniques of high velocity guns,and explosives. The principle tool is the high precision, magnetically imploded, near-solid density liner. The most attractive pulse power system for driving such experiments is an ultra-highcurrent, low impedance, microsecond time-scale source that is economical both the build and operate. Liner specifications vary but in general share requirements for a high degree of symmetry and uniformity after implosion. When imploded in free flight to velocities 10-30 km/sec and kinetic energies of from one to 25 MJ/cm of height, liners are attractive impactors for producing strong (>10 Mbar) shocks in the target. Simple geometries can, in principle, produce multi-shock environments to reach off-hugoniot states. When filled with a compressible material, liners can deliver almost adiabatic compression to the target. When the liner surrounds a (small)nearly incompressible target material, for example a condensed noble gas, a liner can deliver enormous pressure to the target almost isentropically. When the compressible material is a magnetic field, flux compression can results in compressed fields above 1000 tesla in macroscopic volumes for materials studies.In this paper we will review basic scaling argumentsthat set the scale of environments available. We will mention the pulse power technology under development at Los Alamos and provide a summary of results from experiments testing solid metal liners under magnetic drive and a few examples of experiments performed withinterim systems. Other papers in this conference will provide specific proposals for pulse power driven shock-wave experiments.

  11. Comparative analysis of physicochemical properties of root perforation sealer materials

    PubMed Central

    Dorileo, Maura Cristiane Gonçales Orçati; Pedro, Fábio Luis Miranda; Bandeca, Matheus Coelho; Guedes, Orlando Aguirre; Villa, Ricardo Dalla

    2014-01-01

    Objectives This study evaluated the solubility, dimensional alteration, pH, electrical conductivity, and radiopacity of root perforation sealer materials. Materials and Methods For the pH test, the samples were immersed in distilled water for different periods of time. Then, the samples were retained in plastic recipients, and the electrical conductivity of the solution was measured. The solubility, dimensional alteration, and radiopacity properties were evaluated according to Specification No. 57 of the American National Standards Institute/American Dental Association (ANSI/ADA). Statistical analyses were carried out using analysis of variance (ANOVA) and Tukey's test at a significance level of 5%. When the sample distribution was not normal, a nonparametric ANOVA was performed with a Kruskal-Wallis test (α = 0.05). Results The results showed that white structural Portland cement (PC) had the highest solubility, while mineral trioxide aggregate (MTA)-based cements, ProRoot MTA (Dentsply-Tulsa Dental) and MTA BIO (Ângelus Ind. Prod.), had the lowest values. MTA BIO showed the lowest dimensional alteration values and white PC presented the highest values. No differences among the tested materials were observed in the the pH and electrical conductivity analyses. Only the MTA-based cements met the ANSI/ADA recommendations regarding radiopacity, overcoming the three steps of the aluminum step wedge. Conclusions On the basis of these results, we concluded that the values of solubility and dimensional alteration of the materials were in accordance with the ANSI/ADA specifications. PCs did not fulfill the ANSI/ADA requirements regarding radiopacity. No differences were observed among the materials with respect to the pH and electrical conductivity analyses. PMID:25110644

  12. Fundamental properties and applications of low- dimensional materials

    NASA Astrophysics Data System (ADS)

    Kim, Philip

    1999-11-01

    Physics in reduced dimensions has attracted much attention during the last decades owing to the discovery of new phenomena in low-dimensional materials and their potential importance in device applications. The unique properties of these low dimensional materials have been generally understood by considering the increased role of fluctuations and singularities in physical quantities due to the reduction in available phase space. In this thesis, I have investigated the fundamental physical properties of several low dimensional materials and have presented a technological application of these materials. Magnetic flux lines in high temperature superconductors (HTSCs) can be effectively treated as 2+1 dimensional systems due to the large anisotropy of HTSCs. The microscopic structure of the magnetic flux line lattice in Bi 2Sr2CaCu2O8 + x superconducting single crystals was studied at temperatures up to 77 K by Bitter magnetic decoration technique. Analysis of structural correlations shows that the flux line lattices are in the hexatic phase for the high temperature and low field regime, and enables us to estimate the flux line lattice freezing temperature. In addition, dislocation-free decoration images containing up to 80,000 vortices, which are two orders of magnitude larger number than that of previous studies, have been obtained. Analyses of these large length new data shows that the observed flux line lattices are in the random manifold regime with a roughening exponent of 0.44 for length scales up to 80-100 lattice constants. At larger length scales, the data exhibit nonequilibrium features that persist for different cooling rates and field histories. Charge density waves in transition-metal dichalcogenides are a good example of a two dispensional electronic system. A scanning tunneling microscope (STM) was used to fabricate T-phase tantalum diselenide (TaSe2) nanocrystals with sizes ranging from 7 to more than 100 nanometers within the surface layer of 2H phase

  13. Modifications of histamine receptor signaling affect bone mechanical properties in rats.

    PubMed

    Folwarczna, Joanna; Janas, Aleksandra; Pytlik, Maria; Śliwiński, Leszek; Wiercigroch, Marek; Brzęczek, Anna

    2014-02-01

    Histamine receptors are expressed on bone cells and histamine may be involved in regulation of bone metabolism. The aim of the present study was to investigate the effects of loratadine (an H(1) receptor antagonist), ranitidine (an H(2) receptor antagonist) and betahistine (an H(3) receptor antagonist and H(1) receptor agonist) on bone mechanical properties in rats. Loratadine (5 mg/kg/day, po), ranitidine (50 mg/kg/day, po), or betahistine dihydrochloride (5 mg/kg/day, po), were administered for 4 weeks to non-ovariectomized and bilaterally ovariectomized (estrogen-deficient) 3-month-old rats, and their effects were compared with appropriate controls. Serum levels of bone turnover markers, bone mineralization and mechanical properties of the proximal tibial metaphysis, femoral diaphysis and femoral neck were studied. In rats with normal estrogen level, administration of loratadine slightly favorably affected mechanical properties of compact bone, significantly increasing the strength of the femoral neck (p < 0.05), and tending to increase the strength of the femoral diaphysis. Ranitidine did not significantly affect the investigated parameters, and betahistine decreased the strength of the tibial metaphysis (cancellous bone, p < 0.01). There were no significant effects of the drugs on serum bone turnover markers. In estrogen-deficient rats, the drugs did not significantly affect the investigated skeletal parameters. In conclusion, the effects of histamine H(1), H(2) and H(3) receptor antagonists on the skeletal system in rats were differential and dependent on estrogen status. PMID:24905313

  14. Suture materials affect peri-implant bone healing and implant osseointegration.

    PubMed

    Villa, Oscar; Lyngstadaas, Staale P; Monjo, Marta; Satué, Maria; Rønold, Hans J; Petzold, Christiane; Wohlfahrt, Johan C

    2015-09-01

    The aim of this study was to evaluate the effects of the remnants of two suture materials on osseointegration of titanium implants in a rabbit tibial model. Calibrated defects were prepared in the tibia of five Chinchilla rabbits. Filaments of nonresorbable (NR) nylon or resorbable (R) chitosan were placed at the bone to implant interface, whereas control sites had no suture material. After a healing period of 4 weeks, a pull-out test procedure was performed followed by enzymatic analyses of the wound fluid and relative quantification of mRNA levels for bone-related and cytokine markers from the peri-implant bone. A trend toward a reduced pull-out force was observed in the NR group (NR: 23.0 ± 12.8 N; R: 33.9 ± 11.3 N; control: 33.6 ± 24.0 N). Similarly, the bone resorption marker vacuolar type H+-ATPase was increased in the NR group compared with that in the control group (P = 0.041). The R group showed trends for lower alkaline phosphatase activity and osteocalcin expression and higher total protein content and RNA compared with the control group. In this submerged healing model, peri-implant bone healing was marginally affected by the two suture materials tested. However, there was a tendency toward better osseointegration and lower expression of bone resorption markers in the R group compared with the control group. PMID:26369486

  15. ABINIT: First-principles approach to material and nanosystem properties

    NASA Astrophysics Data System (ADS)

    Gonze, X.; Amadon, B.; Anglade, P.-M.; Beuken, J.-M.; Bottin, F.; Boulanger, P.; Bruneval, F.; Caliste, D.; Caracas, R.; Côté, M.; Deutsch, T.; Genovese, L.; Ghosez, Ph.; Giantomassi, M.; Goedecker, S.; Hamann, D. R.; Hermet, P.; Jollet, F.; Jomard, G.; Leroux, S.; Mancini, M.; Mazevet, S.; Oliveira, M. J. T.; Onida, G.; Pouillon, Y.; Rangel, T.; Rignanese, G.-M.; Sangalli, D.; Shaltaf, R.; Torrent, M.; Verstraete, M. J.; Zerah, G.; Zwanziger, J. W.

    2009-12-01

    ABINIT [ http://www.abinit.org] allows one to study, from first-principles, systems made of electrons and nuclei (e.g. periodic solids, molecules, nanostructures, etc.), on the basis of Density-Functional Theory (DFT) and Many-Body Perturbation Theory. Beyond the computation of the total energy, charge density and electronic structure of such systems, ABINIT also implements many dynamical, dielectric, thermodynamical, mechanical, or electronic properties, at different levels of approximation. The present paper provides an exhaustive account of the capabilities of ABINIT. It should be helpful to scientists that are not familiarized with ABINIT, as well as to already regular users. First, we give a broad overview of ABINIT, including the list of the capabilities and how to access them. Then, we present in more details the recent, advanced, developments of ABINIT, with adequate references to the underlying theory, as well as the relevant input variables, tests and, if available, ABINIT tutorials. Program summaryProgram title: ABINIT Catalogue identifier: AEEU_v1_0 Distribution format: tar.gz Journal reference: Comput. Phys. Comm. Programming language: Fortran95, PERL scripts, Python scripts Computer: All systems with a Fortran95 compiler Operating system: All systems with a Fortran95 compiler Has the code been vectorized or parallelized?: Sequential, or parallel with proven speed-up up to one thousand processors. RAM: Ranges from a few Mbytes to several hundred Gbytes, depending on the input file. Classification: 7.3, 7.8 External routines: (all optional) BigDFT [1], ETSF IO [2], libxc [3], NetCDF [4], MPI [5], Wannier90 [6] Nature of problem: This package has the purpose of computing accurately material and nanostructure properties: electronic structure, bond lengths, bond angles, primitive cell size, cohesive energy, dielectric properties, vibrational properties, elastic properties, optical properties, magnetic properties, non-linear couplings, electronic and

  16. Salt matters: How salt affects the rheological and physical properties of gelatine for analogue modelling

    NASA Astrophysics Data System (ADS)

    Brizzi, S.; Funiciello, F.; Corbi, F.; Di Giuseppe, E.; Mojoli, G.

    2016-06-01

    Gelatine is extensively used as analogue material for the easiness to tune its physical and rheological properties. The addition of salt to gelatine is generally adopted to increase the density of the material, improving the scaling of the models. However, the way the addition of salt changes the rheological properties of gelatine is generally underestimated. Here, we investigate both rheological and physical properties (i.e., density and transparency) of type A pig-skin 2.5 wt.% gelatine at T = 10 °C as a function of salt concentration, cNaCl, and ageing time. We established a standard preparation recipe and measuring protocol, yielding to uniform samples with reproducible behaviour. Rheometric measurements show that the presence of salt weakens the gelatine structure, with a decrease of both material rigidity and viscosity as cNaCl increases. Salted gelatine behaviour moves from viscoelastic to dominantly elastic as the ageing time increases. Density and cloudiness also increase with cNaCl. Finally, we present results from subduction interplate seismicity models performed with pure and salted gelatines, showing that the modified material may improve the modelling performance and open new perspectives in experimental tectonics.

  17. Manipulating lipid bilayer material properties using biologically active amphipathic molecules

    NASA Astrophysics Data System (ADS)

    Ashrafuzzaman, Md; Lampson, M. A.; Greathouse, D. V.; Koeppe, R. E., II; Andersen, O. S.

    2006-07-01

    Lipid bilayers are elastic bodies with properties that can be manipulated/controlled by the adsorption of amphipathic molecules. The resulting changes in bilayer elasticity have been shown to regulate integral membrane protein function. To further understand the amphiphile-induced modulation of bilayer material properties (thickness, intrinsic monolayer curvature and elastic moduli), we examined how an enantiomeric pair of viral anti-fusion peptides (AFPs)—Z-Gly-D-Phe and Z-Gly-Phe, where Z denotes a benzyloxycarbonyl group, as well as Z-Phe-Tyr and Z-D-Phe-Phe-Gly—alters the function of enantiomeric pairs of gramicidin channels of different lengths in planar bilayers. For both short and long channels, the channel lifetimes and appearance frequencies increase as linear functions of the aqueous AFP concentration, with no apparent effect on the single-channel conductance. These changes in channel function do not depend on the chirality of the channels or the AFPs. At pH 7.0, the relative changes in channel lifetimes do not vary when the channel length is varied, indicating that these compounds exert their effects primarily by causing a positive-going change in the intrinsic monolayer curvature. At pH 4.0, the AFPs are more potent than at pH 7.0 and have greater effects on the shorter channels, indicating that these compounds now change the bilayer elastic moduli. When AFPs of different anti-fusion potencies are compared, the rank order of the anti-fusion activity and the channel-modifying activity is similar, but the relative changes in anti-fusion potency are larger than the changes in channel-modifying activity. We conclude that gramicidin channels are useful as molecular force transducers to probe the influence of small amphiphiles upon lipid bilayer material properties.

  18. Corrosion and its effect on mechanical properties of materials for advanced combustion systems

    SciTech Connect

    Natesan, K.; Freeman, M.; Mathur, M.

    1996-05-01

    Conceptual designs of advanced combustion systems that utilize coal as a feedstock require high-temperature furnaces and heat transfer surfaces that can operate at temperatures much higher than those prevalent in current coal-fired power plants. The combination of elevated temperatures and hostile combustion environments necessitates development and application of advanced ceramic materials in these designs. The objectives of the present program are to evaluate (a) the chemistry of gaseous and condensed products that arise during combustion of coal; (b) the corrosion behavior of candidate materials in air, slag and salt environments for application in the combustion environments; and (c) the residual mechanical properties of the materials after corrosion. The program emphasizes temperatures in the range of 1000-1400{degrees}C for ceramic materials and 600-1000{degrees}C for metallic alloys. Coal/ash chemistries developed on the basis of thermodynamic/kinetic calculations, together with slags from actual combustors, are used in the program. The materials being evaluated include monolithic silicon carbide from several sources: silicon, nitride, silicon carbide in alumina composites, silicon carbide fibers in a silicon carbide- matrix composite, and some advanced nickel-base alloys. The paper presents results from an ongoing program on corrosion performance of candidate ceramic materials exposed to air, salt and slag environments and their affect on flexural strength and energy absorbed during fracture of these materials.

  19. A thermodynamic approach to obtain materials properties for engineering applications

    NASA Technical Reports Server (NTRS)

    Chang, Y. Austin

    1993-01-01

    With the ever increases in the capabilities of computers for numerical computations, we are on the verge of using these tools to model manufacturing processes for improving the efficiency of these processes as well as the quality of the products. One such process is casting for the production of metals. However, in order to model metal casting processes in a meaningful way it is essential to have the basic properties of these materials in their molten state, solid state as well as in the mixed state of solid and liquid. Some of the properties needed may be considered as intrinsic such as the density, heat capacity or enthalpy of freezing of a pure metal, while others are not. For instance, the enthalpy of solidification of an alloy is not a defined thermodynamic quantity. Its value depends on the micro-segregation of the phases during the course of solidification. The objective of the present study is to present a thermodynamic approach to obtain some of the intrinsic properties and combining thermodynamics with kinetic models to estimate such quantities as the enthalpy of solidification of an alloy.

  20. Material properties from acoustic radiation force step response

    PubMed Central

    Orescanin, Marko; Toohey, Kathleen S.; Insana, Michael F.

    2009-01-01

    An ultrasonic technique for estimating viscoelastic properties of hydrogels, including engineered biological tissues, is being developed. An acoustic radiation force is applied to deform the gel locally while Doppler pulses track the induced movement. The system efficiently couples radiation force to the medium through an embedded scattering sphere. A single-element, spherically-focused, circular piston element transmits a continuous-wave burst to suddenly apply and remove a radiation force to the sphere. Simultaneously, a linear array and spectral Doppler technique are applied to track the position of the sphere over time. The complex shear modulus of the gel was estimated by applying a harmonic oscillator model to measurements of time-varying sphere displacement. Assuming that the stress-strain response of the surrounding gel is linear, this model yields an impulse response function for the gel system that may be used to estimate material properties for other load functions. The method is designed to explore the force-frequency landscape of cell-matrix viscoelasticity. Reported measurements of the shear modulus of gelatin gels at two concentrations are in close agreement with independent rheometer measurements of the same gels. Accurate modulus measurements require that the rate of Doppler-pulse transmission be matched to a priori estimates of gel properties. PMID:19425636

  1. Recommended Best Practices for the Characterization of Storage Properties of Hydrogen Storage Materials

    SciTech Connect

    2010-03-01

    This is a reference guide to common methodologies and protocols for measuring critical performance properties of advanced hydrogen storage materials. It helps users to communicate clearly the relevant performance properties of new materials as they are discovered and tested.

  2. Dynamic tensile material properties of human pelvic cortical bone.

    PubMed

    Kemper, Andrew R; McNally, Craig; Duma, Stefan M

    2008-01-01

    IIn order for finite element models of the human body to predict pelvic injuries accurately, the appropriate material properties must be applied. Therefore, the purpose of this study was to quantify the dynamic material properties of human pelvic cortical bone in tension. In order to accomplish this, a total of 20 tension coupon specimens were obtained from four regions of four human cadaver pelves: anterior ilium wing, posterior ilium wing, superior pubic ramus, and ischium body. For the anterior and posterior regions of the ilium wing, samples were taken in two orientations to investigate any direction dependence. A high-rate servo-hydraulic Material Testing System (MTS) with a custom slack adaptor was used to apply tension loads to failure at a constant loading rate of 0.5 strains/s. The horizontally oriented anterior ilium specimens were found to have a significantly larger ultimate stress (p=0.02), ultimate strain (p>0.01), and modulus (p=0.02) than the vertically oriented anterior ilium specimens. There were no significant differences in ultimate stress (p=0.27), ultimate strain (p=0.85), or modulus (p=0.87) found between horizontally oriented and vertically oriented posterior ilium specimens. However, additional testing should be conducted at specimen orientation 45 degree from the orientations used in the current study to further investigate the effect of specimen orientation on the posterior portion of the ilium wing. There were no significant differences in ultimate stress (p=0.79), ultimate strain (p=0.31), or modulus (p=0.15) found between the superior pubic ramus and ischium body specimens. However, the statistical comparison between superior pubic ramus and ischium body specimens was considered weak due to the limited samples and large variation between subjects. PMID:19141951

  3. Rheological properties of granular materials - Critical parameters and mixing rules

    NASA Astrophysics Data System (ADS)

    Vasilenko, Alisa Victoria

    2011-12-01

    Granular materials can be found at any stage of processing in many industries, such as food, pharmaceuticals, catalysts, and chemicals. These materials exhibit a variety of flow patterns, and their state and behavior differ from application to application. Since there is a lack of fundamental understanding of particulate or powder behavior, multiple problems can be encountered during routine manufacturing. Scale-up can also be a challenge, as the lack of constitutive equations for granular materials forces most scaleup efforts to follow the trial-and-error route. Powder characterization measurements are employed as both a selection tool and a predictive method for the material's process performance. Therefore, it plays a very important role in process and product development. The numerous existing methods used to characterize the flow properties of powders are mostly application-specific and it is not clear how they correlate with each other or with process performance. Moreover, understanding the relationships between the material properties and the processing conditions is necessary for a successful design of a continuous manufacturing system, which has been a major focus for pharmaceutical industry in the recent years. Before such changes can be implemented, a better understanding of fundamental physical phenomena governing powder flow behavior must be developed. In this work we study particulate/powder flow behavior experimentally using several characterization methods, including the Gravitational Displacement Rheometer (an avalanching tester), the rotational shear cell, and the compressibility tester. We establish the variables of interest through correlative comparison and study the differences and similarities between the methods in order to investigate particulate/powder flow behavior during processing and characterization. A mixing rule for principal stresses is developed through investigation of shear behavior of binary mixtures in a shear cell. In order

  4. Designing functionally graded materials with superior load-bearing properties

    PubMed Central

    Zhang, Yu; Sun, Ming-jie; Zhang, Denzil

    2011-01-01

    Ceramic prostheses often fail from fracture and wear. We hypothesize that these failures may be substantially mitigated by an appropriate grading of elastic modulus at the ceramic surface. In this study, we elucidate the effect of elastic modulus profile on the flexural damage resistance of functionally graded materials (FGMs), providing theoretical guidlines for designing FGM with superior load-bearing property. The Young's modulus of the graded structure is assumed to vary in a power-law relation with a scaling exponent n; this is in accordance with experimental observations from our laboratory and elsewhere. Based on the theory for bending of graded beams, we examine the effect of n value and bulk-to-surface modulus ratio (Eb/Es) on stress distribution through the graded layer. Theory predicts that a low exponent (0.15 < n < 0.5), coupled with a relatively small modulus ratio (3 < Eb/Es < 6), is most desirable for reducing the maximum stress and transferring it into the interior, while keeping the surface stress low. Experimentally, we demonstrate that elastically graded materials with various n values and Eb/Es ratios can be fabricated by infiltrating alumina and zirconia with a low-modulus glass. Flexural tests show that graded alumina and zirconia with suitable values of these parameters exhibit superior load-bearing capacity, 20% to 50% higher than their homogeneous counterparts. Improving load-bearing capacity of ceramic materials could have broad impacts on biomedical, civil, structural, and an array of other engineering applications. PMID:22178651

  5. Viscoelastic properties of actin networks influence material transport

    NASA Astrophysics Data System (ADS)

    Stam, Samantha; Weirich, Kimberly; Gardel, Margaret

    2015-03-01

    Directed flows of cytoplasmic material are important in a variety of biological processes including assembly of a mitotic spindle, retraction of the cell rear during migration, and asymmetric cell division. Networks of cytoskeletal polymers and molecular motors are known to be involved in these events, but how the network mechanical properties are tuned to perform such functions is not understood. Here, we construct networks of either semiflexible actin filaments or rigid bundles with varying connectivity. We find that solutions of rigid rods, where unimpeded sliding of filaments may enhance transport in comparison to unmoving tracks, are the fastest at transporting network components. Entangled solutions of semiflexible actin filaments also transport material, but the entanglements provide resistance. Increasing the elasticity of the actin networks with crosslinking proteins slows network deformation further. However, the length scale of correlated transport in these networks is increased. Our results reveal how the rigidity and connectivity of biopolymers allows material transport to occur over time and length scales required for physiological processes. This work was supported by the U. Chicago MRSEC

  6. Flexural stiffness of feather shafts: geometry rules over material properties.

    PubMed

    Bachmann, Thomas; Emmerlich, Jens; Baumgartner, Werner; Schneider, Jochen M; Wagner, Hermann

    2012-02-01

    Flight feathers of birds interact with the flow field during flight. They bend and twist under aerodynamic loads. Two parameters are mainly responsible for flexibility in feathers: the elastic modulus (Young's modulus, E) of the material (keratin) and the geometry of the rachises, more precisely the second moment of area (I). Two independent methods were employed to determine Young's modulus of feather rachis keratin. Moreover, the second moment of area and the bending stiffness of feather shafts from fifth primaries of barn owls (Tyto alba) and pigeons (Columba livia) were calculated. These species of birds are of comparable body mass but differ in wing size and flight style. Whether their feather material (keratin) underwent an adaptation in stiffness was previously unknown. This study shows that no significant variation in Young's modulus between the two species exists. However, differences in Young's modulus between proximal and distal feather regions were found in both species. Cross-sections of pigeon rachises were particularly well developed and rich in structural elements, exemplified by dorsal ridges and a well-pronounced transversal septum. In contrast, cross-sections of barn owl rachises were less profiled but had a higher second moment of area. Consequently, the calculated bending stiffness (EI) was higher in barn owls as well. The results show that flexural stiffness is predominantly influenced by the geometry of the feathers rather than by local material properties. PMID:22246249

  7. Electron Transport Materials: Synthesis, Properties and Device Performance

    SciTech Connect

    Cosimbescu, Lelia; Wang, Liang; Helm, Monte L.; Polikarpov, Evgueni; Swensen, James S.; Padmaperuma, Asanga B.

    2012-06-01

    We report the design, synthesis and characterization, thermal and photophysical properties of two silane based electron transport materials, dibenzo[b,d]thiophen-2-yltriphenylsilane (Si{phi}87) and (dibenzo[b,d]thiophen-2-yl)diphenylsilane (Si{phi}88) and their performance in blue organic light emitting devices (OLEDs). The utility of these materials in blue OLEDs with iridium (III) bis[(4,6-difluorophenyl)-pyridinato-N,C']picolinate (Firpic) as the phosphorescent emitter was demonstrated. Using the silane Si{phi}87 as the electron transport material (ETm) an EQE of 18.2% was obtained, with a power efficiency of 24.3 lm/W (5.8V at 1mA/cm{sup 2}), in a heterostructure. When Si{phi}88 is used, the EQE is 18.5% with a power efficiency of 26.0 lm/W (5.5V at 1mA/cm{sup 2}).

  8. Characterization of Triaxial Braided Composite Material Properties for Impact Simulation

    NASA Technical Reports Server (NTRS)

    Roberts, Gary D.; Goldberg, Robert K.; Biniendak, Wieslaw K.; Arnold, William A.; Littell, Justin D.; Kohlman, Lee W.

    2009-01-01

    The reliability of impact simulations for aircraft components made with triaxial braided carbon fiber composites is currently limited by inadequate material property data and lack of validated material models for analysis. Improvements to standard quasi-static test methods are needed to account for the large unit cell size and localized damage within the unit cell. The deformation and damage of a triaxial braided composite material was examined using standard quasi-static in-plane tension, compression, and shear tests. Some modifications to standard test specimen geometries are suggested, and methods for measuring the local strain at the onset of failure within the braid unit cell are presented. Deformation and damage at higher strain rates is examined using ballistic impact tests on 61- by 61- by 3.2-mm (24- by 24- by 0.125-in.) composite panels. Digital image correlation techniques were used to examine full-field deformation and damage during both quasi-static and impact tests. An impact analysis method is presented that utilizes both local and global deformation and failure information from the quasi-static tests as input for impact simulations. Improvements that are needed in test and analysis methods for better predictive capability are examined.

  9. The Effect of Material Properties on Dynamo Generation in Planets

    NASA Astrophysics Data System (ADS)

    Vilim, Ryan

    2015-10-01

    In this thesis I use a three dimensional numerical dynamo model to explore the effect of novel material properties and core states on magnetic field generation in the planet Mercury, and in rocky extra-solar planets. In the first part of this work I focus on the recent evidence of pressure induced metallisation in materials which commonly comprise planetary mantles. In this scenario the materials which make up the lower mantle of a planet conduct electricity with a conductivity similar to that of iron. I show that a metallised mantle changes the way in which magnetic field is generated by providing a new source of magnetic shear between the fluid outer core and the solid mantle. I then show that this has the effect of making planetary magnetic fields more difficult to observe from Earth. The second and third parts of this work focus on the planet Mercury. First, I incorporate recent evidence of buoyancy sources mid-way through Mercury's liquid core (known as "snow zones") to show that they can explain the weak observed magnetic field of Mercury. In a second project on Mercury I test whether recent evidence of a dense solid layer at the top of Mercury's core, attributed to a solid, electrically conducting layer of FeS, could help explain Mercury's weak magnetic field. I find that the addition of this layer causes the dynamo to generate a strong, dipolar magnetic field, which does not match the observations made by the MESSENGER spacecraft.

  10. DEVELOPMENT AND APPLICATION OF MATERIALS PROPERTIES FOR FLAW STABILITY ANALYSIS IN EXTREME ENVIRONMENT SERVICE

    SciTech Connect

    Sindelar, R; Ps Lam, P; Andrew Duncan, A; Bruce Wiersma, B; Karthik Subramanian, K; James Elder, J

    2007-04-18

    Discovery of aging phenomena in the materials of a structure may arise after its design and construction that impact its structural integrity. This condition can be addressed through a demonstration of integrity with the material-specific degraded conditions. Two case studies of development of fracture and crack growth property data, and their application in development of in-service inspection programs for nuclear structures in the defense complex are presented. The first case study covers the development of fracture toughness properties in the form of J-R curves for rolled plate Type 304 stainless steel with Type 308 stainless steel filler in the application to demonstrate the integrity of the reactor tanks of the heavy water production reactors at the Savannah River Site. The fracture properties for the base, weld, and heat-affected zone of the weldments irradiated at low temperatures (110-150 C) up to 6.4 dpa{sub NRT} and 275 appm helium were developed. An expert group provided consensus for application of the irradiated properties for material input to acceptance criteria for ultrasonic examination of the reactor tanks. Dr. Spencer H. Bush played a lead advisory role in this work. The second case study covers the development of fracture toughness for A285 carbon steel in high level radioactive waste tanks. The approach in this case study incorporated a statistical experimental design for material testing to address metallurgical factors important to fracture toughness. Tolerance intervals were constructed to identify the lower bound fracture toughness for material input to flaw disposition through acceptance by analysis.

  11. TRITIUM EFFECTS ON DYNAMIC MECHANICAL PROPERTIES OF POLYMERIC MATERIALS

    SciTech Connect

    Clark, E

    2008-11-12

    Dynamic mechanical analysis has been used to characterize the effects of tritium gas (initially 1 atm. pressure, ambient temperature) exposure over times up to 2.3 years on several thermoplastics-ultrahigh molecular weight polyethylene (UHMW-PE), polytetrafluoroethylene (PTFE), and Vespel{reg_sign} polyimide, and on several formulations of elastomers based on ethylene propylene diene monomer (EPDM). Tritium exposure stiffened the elastic modulus of UHMW-PE up to about 1 year and then softened it, and reduced the viscous response monotonically with time. PTFE initially stiffened, however the samples became too weak to handle after nine months exposure. The dynamic properties of Vespel{reg_sign} were not affected. The glass transition temperature of the EPDM formulations increased approximately 4 C. following three months tritium exposure.

  12. Interfacial properties and design of functional energy materials.

    PubMed

    Sumpter, Bobby G; Liang, Liangbo; Nicolaï, Adrien; Meunier, Vincent

    2014-11-18

    CONSPECTUS: The vital importance of energy to society continues to demand a relentless pursuit of energy responsive materials that can bridge fundamental chemical structures at the molecular level and achieve improved functionality and performance. This demand can potentially be realized by harnessing the power of self-assembly, a spontaneous process where molecules or much larger entities form ordered aggregates as a consequence of predominately noncovalent (weak) interactions. Self-assembly is the key to bottom-up design of molecular devices, because the nearly atomic-level control is very difficult to realize in a top-down, for example, lithographic, approach. However, while function in simple systems such as single crystals can often be evaluated a priori, predicting the function of the great variety of self-assembled molecular architectures is complicated by the lack of understanding and control over nanoscale interactions, mesoscale architectures, and macroscale order. To establish a foundation toward delivering practical solutions, it is critical to develop an understanding of the chemical and physical mechanisms responsible for the self-assembly of molecular and hybrid materials on various support substrates. Typical molecular self-assembly involves noncovalent intermolecular and substrate-molecule interactions. These interactions remain poorly understood, due to the combination of many-body interactions compounded by local or collective influences from the substrate atomic lattice and electronic structure. Progress toward unraveling the underlying physicochemical processes that control the structure and macroscopic physical, chemical, mechanical, electrical, and transport properties of materials increasingly requires tight integration of theory, modeling, and simulation with precision synthesis, advanced experimental characterization, and device measurements. Theory, modeling, and simulation can accelerate the process of materials understanding and design

  13. The properties and weldability of materials for fusion reactor applications

    SciTech Connect

    Chin, B.A.; Kee, C.K.; Wilcox, R.C.; Zinkle, S.J.

    1991-11-15

    Low-activation austenitic stainless steels have been suggested for applications within fusion reactors. The use of these nickel-free steels will help to reduce the radioactive waste management problem after service. one requirement for such steels is the ability to obtain sound welds for fabrication purposes. Thus, two austenitic Fe-Cr-Mn alloys were studied to characterize the welded microstructure and mechanical properties. The two steels investigated were a Russian steel (Fe-11.6Cr19.3Mn-0.181C) and an US steel (Fe-12.lCr-19.4Mn-0.24C). Welding was performed using a gas tungsten arc welding (GTAW) process. Microscopic examinations of the structure of both steels were conducted. The as-received Russian steel was found to be in the annealed state. Only the fusion zone and the base metal were observed in the welded Russian steel. No visible heat affected zone was observed. Examination revealed that the as-received US steel was in the cold rolled condition. After welding, a fusion zone and a heat affected zone along with the base metal region were found.

  14. Interfacial Properties and Design of Functional Energy Materials

    SciTech Connect

    Sumpter, Bobby G; Liang, Liangbo; Nicolai, Adrien; Meunier, V.

    2014-01-01

    The vital importance of energy to society continues to demand a relentless pursuit of energy responsive materials that can bridge fundamental chemical structures at the molecular level and achieve improved functionality, such as efficient energy conversion/storage/transmission, over multiple length scales. This demand can potentially be realized by harnessing the power of self-assembly a spontaneous process where molecules or much larger entities form ordered aggregates as a consequence of predominately non-covalent (weak) interactions. Self-assembly is the key to bottom-up design of molecular devices, because the nearly atomic-level control is very difficult to realize in a top-down, e.g., lithographic approach. However, while function (e.g., charge mobility) in simple systems such as single crystals can often be predicted, predicting the function of the great variety of self-assembled molecular architectures is complicated by the lack of understanding and control over nanoscale interactions, mesoscale architectures, and macroscale (long-range) order. To establish a foundation toward delivering practical solutions, it is critical to develop an understanding of the chemical and physical mechanisms responsible for the self-assembly of molecular and hybrid materials on various substrates. Typically molecular self-assembly involves poorly understood non-covalent intermolecular and substrate-molecule interactions compounded by local and/or collective influences from the substrate atomic lattice (symmetry and/or topological features) and electronic structure. Thus, progress towards unraveling the underlying physicochemical processes that control the structure and macroscopic physical, mechanical, electrical, and transport properties of materials increasingly requires tight integration of theory, modeling and simulation with precision synthesis, advanced experimental characterization, and device measurements. In this mode, theory and simulation can greatly accelerate the

  15. Phonon Properties of Materials from Neutron Resonance Doppler Broadening Measurements

    NASA Astrophysics Data System (ADS)

    Eric Lynn, J.

    2002-12-01

    At low temperatures the Doppler broadened widths of neutron resonances are strongly affected by the phonon characteristics of the material used for making the cross-section measurement. The Doppler width can be expressed in terms of the moments of the phonon spectrum carried by the atomic species with the resonant cross-section. Cross-section measurements made with tungsten and tantalum metals are reviewed here and compared with phonon information obtained by other methods. Applications of the method to a plutonium-gallium alloy and to some lanthanum barium cuprates are described briefly. We discuss possible extensions of the technique and how an epithermal flight path at the SNS may be advantageous.

  16. 14 CFR 23.613 - Material strength properties and design values.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... item is tested before use to determine that the actual strength properties of that particular item will... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Material strength properties and design... Design and Construction § 23.613 Material strength properties and design values. (a) Material...

  17. 14 CFR 23.613 - Material strength properties and design values.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... item is tested before use to determine that the actual strength properties of that particular item will... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Material strength properties and design... Design and Construction § 23.613 Material strength properties and design values. (a) Material...

  18. 14 CFR 23.613 - Material strength properties and design values.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... item is tested before use to determine that the actual strength properties of that particular item will... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Material strength properties and design... Design and Construction § 23.613 Material strength properties and design values. (a) Material...

  19. 14 CFR 23.613 - Material strength properties and design values.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... item is tested before use to determine that the actual strength properties of that particular item will... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Material strength properties and design... Design and Construction § 23.613 Material strength properties and design values. (a) Material...

  20. 14 CFR 23.613 - Material strength properties and design values.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... item is tested before use to determine that the actual strength properties of that particular item will... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Material strength properties and design... Design and Construction § 23.613 Material strength properties and design values. (a) Material...

  1. Quantitative property-structural relation modeling on polymeric dielectric materials

    NASA Astrophysics Data System (ADS)

    Wu, Ke

    Nowadays, polymeric materials have attracted more and more attention in dielectric applications. But searching for a material with desired properties is still largely based on trial and error. To facilitate the development of new polymeric materials, heuristic models built using the Quantitative Structure Property Relationships (QSPR) techniques can provide reliable "working solutions". In this thesis, the application of QSPR on polymeric materials is studied from two angles: descriptors and algorithms. A novel set of descriptors, called infinite chain descriptors (ICD), are developed to encode the chemical features of pure polymers. ICD is designed to eliminate the uncertainty of polymer conformations and inconsistency of molecular representation of polymers. Models for the dielectric constant, band gap, dielectric loss tangent and glass transition temperatures of organic polymers are built with high prediction accuracy. Two new algorithms, the physics-enlightened learning method (PELM) and multi-mechanism detection, are designed to deal with two typical challenges in material QSPR. PELM is a meta-algorithm that utilizes the classic physical theory as guidance to construct the candidate learning function. It shows better out-of-domain prediction accuracy compared to the classic machine learning algorithm (support vector machine). Multi-mechanism detection is built based on a cluster-weighted mixing model similar to a Gaussian mixture model. The idea is to separate the data into subsets where each subset can be modeled by a much simpler model. The case study on glass transition temperature shows that this method can provide better overall prediction accuracy even though less data is available for each subset model. In addition, the techniques developed in this work are also applied to polymer nanocomposites (PNC). PNC are new materials with outstanding dielectric properties. As a key factor in determining the dispersion state of nanoparticles in the polymer matrix

  2. Reliability of FEA on the Results of Mechanical Properties of Materials.

    PubMed

    Gomes, Erica Alves; Diana, Hugo Henrique; Oliveira, Juliana Santos; Silva-Sousa, Yara Teresinha Corrêa; Faria, Adriana Cláudia Lapria; Ribeiro, Ricardo Faria

    2015-01-01

    The present study evaluated the reliability of FEA on the results of different mechanical properties (E and v) of materials. Two 3D models of a maxillary canine with endodontic treatment, intracanal post, composite resin core and restored with porcelain-fused-to-metal crown were generated according to micro-CT images. Two groups with different E and ν values for porcelain, metal coping alloy, resin cement and composite resin were established. The materials' properties for group GL were based on literature data, while for group GIE the impulse excitation technique was used. A load of 180 N was applied at 45° on the incisal third of the lingual surface of the canine tooth. All models were supported by the periodontal ligament (x=y=z=0). The von Mises stress (VMS) was calculated. The stress values revealed differences between the groups for both VMS distribution and value. The porcelain (GL: 5.966 MPa; GIE: 7.478 MPa), metal coping (GL: 3.811 MPa; GIE: 0.973 MPa) and core (GL: 4.771 MPa; GIE: 0.026 MPa) were significantly affected. In conclusion, this study showed that the determination of mechanical properties (E and ν) of materials is essential for the reliability on the results of FEA. PMID:26963214

  3. Composite Materials with Magnetically Aligned Carbon Nanoparticles Having Enhanced Electrical Properties and Methods of Preparation

    NASA Technical Reports Server (NTRS)

    Hong, Haiping (Inventor); Peterson, G.P. (Bud) (Inventor); Salem, David R. (Inventor)

    2016-01-01

    Magnetically aligned carbon nanoparticle composites have enhanced electrical properties. The composites comprise carbon nanoparticles, a host material, magnetically sensitive nanoparticles and a surfactant. In addition to enhanced electrical properties, the composites can have enhanced mechanical and thermal properties.

  4. Material properties of femoral cancellous bone in axial loading. Part I: Time independent properties.

    PubMed

    Rohlmann, A; Zilch, H; Bergmann, G; Kölbel, R

    1980-01-01

    The time independent material behavior of cylindrical specimens obtained from the cancelous bone of 20 cadaveric human femora were determined. In this part of the publication, the nominal values for compressive strength, limits of elasticity (yield point), strain, elastic modulus and apparent density are being reported for the cancellous bone of the femoral head and condyle. The correlations between the various parameters are analysed. A positive linear correlation between the four parameters compressive stength, limit of elasticity, modulus of elasticity and apparent density could not be excluded. The material properties vary considerably both within one single bone and between individuals. Compressive strength, modulus of elasticity and apparent density found for cancellous bone of the femoral head are greater than those found in the condyles. Within the condyles, compressive strength, elastic modulus and apparent density increase from the proximal parts to the parts closer to the joint. The medial femoral condyle showed higher compressive strength than the lateral one. Relating each of the three other parameters to the apparent density of the individual specimen did not result in equalizing the data for the material properties. This indicates that the mechanical properties of cancellous bone are strongly related to the direction of loading. PMID:7458606

  5. Effect of Isotropic Assumption on Material Property Reconstructions of the Human Brain using Magnetic Resonance Elastography

    NASA Astrophysics Data System (ADS)

    Anderson, Aaron; Johnson, Curtis; Holtrop, Joseph; McGarry, Mathew; Paulsen, Keith; Sutton, Bradley; van Houten, Elijah; Georgiadis, John

    2015-03-01

    Neurodegenerative diseases affect the microstructure of the brain and thus have a significant effect on the tissue mechanical properties. In vivo techniques, like magnetic resonance elastography (MRE), have shown promise as a contrast technique for disease detection. MRE is a non-invasive technique for measuring the viscoelastic mechanical properties of biological tissue by applying a low-amplitude shear wave, capturing the wave patterns with specialized magnetic resonance imaging techniques, and employing an isotropic nonlinear inversion (NLI) material property reconstruction. When distinctly different shear wave patterns are applied, NLI reconstructs differences in the real component of the shear modulus of ~ 2 [ kPa ] within well ordered white matter (WM). The difference is significant due to the human brain only having a range of real shear modulus from 0 [ kPa ] (cerebral spinal fluid) to ~ 5 [ kPa ] (white matter). The focus of this investigation is to quantify the effect of propagation direction on the reconstructed material properties and examine their relationship to the underlying microstructure in a well ordered, WM regions of the brain (corpus callosum).

  6. Structures and properties of materials recovered from high shock pressures

    SciTech Connect

    Nellis, W.J.

    1994-03-01

    Shock compression produces high dynamic pressures, densities, temperatures, and their quench rates. Because of these extreme conditions, shock compression produces materials with novel crystal structures, microstructures, and physical properties. Using a 6.5-m-long two-stage gun, we perform experiments with specimens up to 10 mm in diameter and 0.001--1 mm thick. For example, oriented disks of melt-textured superconducting YBa{sub 2}Cu{sub 3}O{sub 7} were shocked to 7 GPa without macroscopic fracture. Lattice defects are deposited in the crystal, which improve magnetic hysteresis at {approximately}1 kOe. A computer code has been developed to simulate shock compaction of 100 powder particles. Computations will be compared with experiments with 15--20 {mu}m Cu powders. The method is applicable to other powders and dynamic conditions.

  7. CW laser generated ultrasound techniques for microstructure material properties evaluation

    NASA Astrophysics Data System (ADS)

    Thursby, Graham; Culshaw, Brian; Pierce, Gareth; Cleary, Alison; McKee, Campbell; Veres, Istvan

    2009-03-01

    Mechanical properties of materials may be obtained from the inversion of ultrasonic Lamb wave dispersion curves. In order to do this broadband excitation and detection of ultrasound is required. As sample size and, in particular, thickness, are reduced to those of microstructures, ultrasound frequencies in the range of the gigahertz region will be required. We look at two possible cw laser excitation techniques which, having far lower peak powers than the more frequently used Q-switched lasers, therefore give a negligible risk of damaging the sample through ablation. In the first method the modulation frequency of a sinusoidally modulated laser is swept over the required range. In the second, the laser is modulated with a series of square pulses whose timing is given by a PRBS (pseudo random binary sequence) in the form of a modified m-sequence.

  8. Piezoelectric properties of rhombohedral ferroelectric materials with phase transition

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaofang; Soh, A. K.

    2015-12-01

    The temporal evolution of domain structure and its piezoelectric behavior of ferroelectric material BaTiO3 during the transition process from rhombohedral to tetragonal phase under an applied electric field have been studied by employing Landau-Ginzburg theory and the phase-field method. The results obtained show that, during the transformation process, the intermediate phase was monoclinic MA phase, and several peak values of piezoelectric coefficient appeared at the stage where obvious change of domain pattern occurred. In addition, by comparing the cases of applied electric field with different frequencies, it was found that the maximum piezoelectric coefficient obtained decreased with increasing frequency value. These results are of great significance in tuning the properties of engineering domains in ferroelectrics, and could provide more fundamentals to the design of ferroelectric devices.

  9. The effects of material properties and confinement on DDT

    SciTech Connect

    Lee, E.L.; Weston, A.M.; Aldis, D.F.

    1990-03-13

    We have used a DDT numerical code, RDUCT, to evaluate the effect of material properties and confinement on DDT in porous beds. RDUCT is a 1-D solid and gas two phase hydrodynamic program that computes deflagration to detonation transition in porous beds, using and ignition and growth'' type reaction model in a solid phase Lagrange coordinate system. The calculation model contains tamper masses at both ends of the reacting bed and is ignited by a squib at one end. Here RDUCT is used to compute the growth of reaction in porous bed inside a rigid tube. The input parameters are varied to produce changes in ignition, burn rate, and confinement. The results of this study illustrate the great sensitivity of the DDT phenomenon to these basic parameters. Implications to modelling and to practical problems of hazard are discussed. 15 refs., 19 figs., 2 tabs.

  10. Determination of the properties of viscoelastic materials using spherical nanoindentation

    NASA Astrophysics Data System (ADS)

    Martynova, Elena

    2016-02-01

    The article is devoted to determining the properties of linearly viscoelastic isotropic materials from the experiment on the introduction of a spherical indenter at a constant-rate displacement in a viscoelastic sample. The results are based on the Lee-Radok (J. Appl. Mech. 27:438-444, 1960) solution of the viscoelastic contact problem. An exact formula is obtained for calculation of the relaxation function using indentation load-displacement data. To illustrate the application of this formula, it is used to find the relaxation function of polymethyl methacrylate (PMMA). The relaxation function found in the article is compared with data measured in a conventional test to evaluate the suitability of the proposed method.

  11. Nonlinear elastic properties of various man-made materials

    SciTech Connect

    Darvennes, C.M.; Hou, X.

    1998-12-31

    Second harmonic generation was measured in several man-made materials for possible application of nonlinear elastic properties to non-destructive testing. Samples included several thicknesses of two types of carbon fiber/polymer matrix composites, three types of concretes, and plywood. Steel and Aluminum specimens were used as references and one of the composite samples was evaluated before and after fatigue cycles. Some interesting observations were made: (1) the two composites were much more nonlinear than the metals, (2) the concretes and the wood were extremely absorptive, (3) one of the concrete samples exhibited a third harmonic but no second harmonic, and (4) fatigue cycles significantly increased the second harmonic, even though no damage was observed by C-scan. The possible applications of these results to NDE will be discussed.

  12. Electronic correlation and transport properties of nuclear fuel materials

    NASA Astrophysics Data System (ADS)

    Yin, Quan; Kutepov, Andrey; Haule, Kristjan; Kotliar, Gabriel; Savrasov, Sergey Y.; Pickett, Warren E.

    2011-11-01

    The electronic structures and transport properties of a series of actinide monocarbides, mononitrides, and dioxides are studied systematically using a combination of density-functional theory and dynamical mean-field theory. The studied materials present different electronic correlation strength and degree of localization of 5f electrons, where a metal-insulator boundary naturally lies within. In the spectral function of Mott-insulating uranium oxide, a resonance peak is observed in both theory and experiment and may be understood as a generalized Zhang-Rice state. We also investigate the interplay between electron-electron and electron-phonon interactions, both of which are responsible for the transport in the metallic compounds. Our findings allow us to gain insight in the roles played by different scattering mechanisms, and suggest how to improve their thermal conductivities.

  13. Effective properties of a cemented or an injected granular material

    NASA Astrophysics Data System (ADS)

    Benhamida, A.; Bouchelaghem, F.; Dumontet, H.

    2005-02-01

    In this paper the macroscopic elastic properties of injected or cemented sands are derived from the characteristics of the constituents and the analysis of the microstructure using a multi-scale modelling approach. Particular interest is given to the choice of the representative elementary volume, by relying on existing microstructural data. The periodic homogenization is adopted and required numerical solutions are performed by the finite element method. An assessment of the validity of the multi-scale approach is achieved through comparison with theoretical and experimental results on cemented and injected granular media reported in the literature. The capabilities of the model are also used to investigate the influence of geometrical and mechanical microscale parameters on the macroscopic behaviour of the treated materials. Copyright

  14. Electronic correlation and transport properties of nuclear fuel materials

    SciTech Connect

    Yin Quan; Kutepov, Andrey; Haule, Kristjan; Kotliar, Gabriel; Savrasov, Sergey Y.; Pickett, Warren E.

    2011-11-15

    The electronic structures and transport properties of a series of actinide monocarbides, mononitrides, and dioxides are studied systematically using a combination of density-functional theory and dynamical mean-field theory. The studied materials present different electronic correlation strength and degree of localization of 5f electrons, where a metal-insulator boundary naturally lies within. In the spectral function of Mott-insulating uranium oxide, a resonance peak is observed in both theory and experiment and may be understood as a generalized Zhang-Rice state. We also investigate the interplay between electron-electron and electron-phonon interactions, both of which are responsible for the transport in the metallic compounds. Our findings allow us to gain insight in the roles played by different scattering mechanisms, and suggest how to improve their thermal conductivities.

  15. Amplified Spontaneous Emission Properties of Semiconducting Organic Materials

    PubMed Central

    Calzado, Eva M.; Boj, Pedro G.; Díaz-García, María A.

    2010-01-01

    This paper aims to review the recent advances achieved in the field of organic solid-state lasers with respect to the usage of semiconducting organic molecules and oligomers in the form of thin films as active laser media. We mainly focus on the work performed in the last few years by our research group. The amplified spontaneous emission (ASE) properties, by optical pump, of various types of molecules doped into polystyrene films in waveguide configuration, are described. The various systems investigated include N,N′-bis(3-methylphenyl)-N,N′-diphenylbenzidine (TPD), several perilenediimide derivatives (PDIs), as well as two oligo-phenylenevinylene derivatives. The ASE characteristics, i.e., threshold, emission wavelength, linewidth, and photostability are compared with that of other molecular materials investigated in the literature. PMID:20640167

  16. Stress in Context: Morpho-Syntactic Properties Affect Lexical Stress Assignment in Reading Aloud

    PubMed Central

    Spinelli, Giacomo; Sulpizio, Simone; Primativo, Silvia; Burani, Cristina

    2016-01-01

    Recent findings from English and Russian have shown that grammatical category plays a key role in stress assignment. In these languages, some grammatical categories have a typical stress pattern and this information is used by readers. However, whether readers are sensitive to smaller distributional differences and other morpho-syntactic properties (e.g., gender, number, person) remains unclear. We addressed this issue in word and non-word reading in Italian, a language in which: (1) nouns and verbs differ in the proportion of words with a dominant stress pattern; (2) information specified by words sharing morpho-syntactic properties may contrast with other sources of information, such as stress neighborhood. Both aspects were addressed in two experiments in which context words were used to induce the desired morpho-syntactic properties. Experiment 1 showed that the relatively different proportions of stress patterns between grammatical categories do not affect stress processing in word reading. In contrast, Experiment 2 showed that information specified by words sharing morpho-syntactic properties outweighs stress neighborhood in non-word reading. Thus, while general information specified by grammatical categories may not be used by Italian readers, stress neighbors with morpho-syntactic properties congruent with those of the target stimulus have a primary role in stress assignment. These results underscore the importance of expanding investigations of stress assignment beyond single words, as current models of single-word reading seem unable to account for our results. PMID:27445910

  17. Stress in Context: Morpho-Syntactic Properties Affect Lexical Stress Assignment in Reading Aloud.

    PubMed

    Spinelli, Giacomo; Sulpizio, Simone; Primativo, Silvia; Burani, Cristina

    2016-01-01

    Recent findings from English and Russian have shown that grammatical category plays a key role in stress assignment. In these languages, some grammatical categories have a typical stress pattern and this information is used by readers. However, whether readers are sensitive to smaller distributional differences and other morpho-syntactic properties (e.g., gender, number, person) remains unclear. We addressed this issue in word and non-word reading in Italian, a language in which: (1) nouns and verbs differ in the proportion of words with a dominant stress pattern; (2) information specified by words sharing morpho-syntactic properties may contrast with other sources of information, such as stress neighborhood. Both aspects were addressed in two experiments in which context words were used to induce the desired morpho-syntactic properties. Experiment 1 showed that the relatively different proportions of stress patterns between grammatical categories do not affect stress processing in word reading. In contrast, Experiment 2 showed that information specified by words sharing morpho-syntactic properties outweighs stress neighborhood in non-word reading. Thus, while general information specified by grammatical categories may not be used by Italian readers, stress neighbors with morpho-syntactic properties congruent with those of the target stimulus have a primary role in stress assignment. These results underscore the importance of expanding investigations of stress assignment beyond single words, as current models of single-word reading seem unable to account for our results. PMID:27445910

  18. Contaminant tailing in highly heterogeneous porous formations: Sensitivity on model selection and material properties

    NASA Astrophysics Data System (ADS)

    Maghrebi, Mahdi; Jankovic, Igor; Weissmann, Gary S.; Matott, L. Shawn; Allen-King, Richelle M.; Rabideau, Alan J.

    2015-12-01

    Coupled impacts of slow advection, diffusion and sorption were investigated using two heterogeneity models that differ in structure and in the mathematical framework that was used to simulate flow and transport and to quantify contaminant tailing. Both models were built using data from a highly heterogeneous exposure of the Borden Aquifer at a site located 2 km north-west of the Stanford-Waterloo experimental site at Canadian Forces Base Borden, Ontario, Canada. The inclusions-based model used a simplified representation of the different materials found at the site, while the second model was based on transitional probability geostatistics of the formation. These two models were used to investigate sensitivity of contaminant tailing on model selection and on geometric and material properties. While simulations were based on data collected at Borden, models were exercised beyond the geometric and material properties that characterize the site. Various realizations have identified very low conductive silty clay, found at volume fraction of 23.4%, as the material with dominant influence on tailing, and vertical diffusion in and out of low conductive units, affected by sorption, as the dominant transport mechanism causing tailing. The two models yielded almost identical transport results when vertical correlation lengths of silty clay were matched. Several practical implications relevant for characterization of low conductive units were identified and briefly discussed.

  19. Viscoelastic effective properties of two types of heterogeneous materials.

    NASA Astrophysics Data System (ADS)

    Cornet, Jan; Dabrowski, Marcin; Schmid, Daniel

    2015-04-01

    In the past, a lot of efforts have been put to describe two end cases of rock behaviors: elasticity and viscosity. In recent years, more focus has been brought on the intermediate viscoelastic cases which describe better the rheology of rocks such as shales. Shales are typically heterogeneous and the question arises as to how to derive their effective properties so that they can be approximated as homogeneous media. This question has already been dealt with at the elastic and viscous limit but still remains for some cases in between. Using MILAMIN, a fast finite element solver for large problems, we numerically investigate different approaches to derive the effective properties of several viscoelastic media. Two types of geometries are considered: layered and inclusion based media. We focus on two dimensional plane strain problems considering two phase composites deformed under pure shear. We start by investigating the case of transversely isotropic layered media made of two Maxwell materials. Using the Backus averaging method we discuss the degree of relevance of this averaging by considering some parameters as: layer periodicity, layer thickness and layer interface roughness. Other averaging methods are also discussed which provide a broader perspective on the performances of Backus averaging. In a second part we move on to inclusion based models. The advantage of these models compared to the previous one is that they provide a better approximation to real microstructures in rocks. The setup we consider in this part is the following: some viscous circular inclusions are embedded in an elastic matrix. Both the inclusions and the matrix are homogeneous but the inclusions are purely isotropic while the matrix can also be anisotropic. In order to derive the effective viscoelastic properties of the medium we use two approaches: the self-consistent averaging and the differential effective medium theory. The idea behind self-consistency is to assume that the inclusions

  20. Culture surfaces coated with various implant materials affect chondrocyte growth and metabolism.

    PubMed

    Hambleton, J; Schwartz, Z; Khare, A; Windeler, S W; Luna, M; Brooks, B P; Dean, D D; Boyan, B D

    1994-07-01

    to culture surface was comparable, differing primarily in magnitude. Cell maturation-dependent effects were evident when enzyme activity in trypsinized and scraped cells was compared. These results indicate that different surface materials affect chondrocyte metabolism and phenotypic expression in vitro and suggest that implant materials may modulate the phenotypic expression of cells in vivo. PMID:7520486

  1. Ultraviolet Radiation Affects Thoratec HeartMate II Driveline Mechanical Properties: A Pilot Experiment.

    PubMed

    Evans, Annicka C; Wright, G Andrew; McCandless, Sean P; Stoker, Sandi; Miller, Dylan; Reid, Bruce B; Horne, Benjamin D; Afshar, Kia; Kfoury, Abdallah G

    2015-01-01

    Longevity and quality of life for left ventricular assist device (LVAD) patients are plagued by driveline exit site infections. Ultraviolet (UV) radiation, a current treatment in wound healing clinics, could potentially treat LVAD exit site infections. However, the effect of UV radiation on the tensile properties of HeartMate II (HMII) driveline material is unknown. The sleeve of a single HMII driveline was distributed into six exposure groups (n = 10/group). The six groups were further divided into two treatment cohorts designed to replicate wound treatment schedules of postimplant LVAD patients. Strip biaxial tensile tests were performed on both unexposed and exposed samples to analyze changes in material elasticity (Young's modulus), point of deformation (yield strength), and breaking point. Our data suggest that UV exposure changes the elasticity of the HMII driveline. However, the material endured aberrantly large forces and the properties remained within the safety threshold of device performance. This study warrants further examination of the effect of UV light on driveline material, to determine safety, reliability, and efficacy of UV treatment on exit site infections. PMID:26102175

  2. Hygrothermal Material Properties for Soils in Building Science

    SciTech Connect

    Pallin, Simon B; Kehrer, Manfred

    2013-01-01

    Hygrothermal performance of soils coupled to buildings is complicated because of the dearth of information on soil properties. However they are important when numerical simulation of coupled heat and moisture transport for below-grade building components are performed as their temperature and moisture content has an influence on the durability of the below-grade building component. Soils can be classified by soil texture. According to the Unified Soil Classification System (USCA), 12 different soils can be defined on the basis of three soil components: clay, sand, and silt. This study shows how existing material properties for typical American soils can be transferred and used for the calculation of the coupled heat and moisture transport of building components in contact with soil. Furthermore a thermal validation with field measurements under known boundary conditions is part of this study, too. Field measurements for soil temperature and moisture content for two specified soils are carried out right now under known boundary conditions. As these field measurements are not finished yet, the full hygrothermal validation is still missing.

  3. Analysis of nonlinear optical properties in donor–acceptor materials

    SciTech Connect

    Day, Paul N.; Pachter, Ruth; Nguyen, Kiet A.

    2014-05-14

    Time-dependent density functional theory has been used to calculate nonlinear optical (NLO) properties, including the first and second hyperpolarizabilities as well as the two-photon absorption cross-section, for the donor-acceptor molecules p-nitroaniline and dimethylamino nitrostilbene, and for respective materials attached to a gold dimer. The CAMB3LYP, B3LYP, PBE0, and PBE exchange-correlation functionals all had fair but variable performance when compared to higher-level theory and to experiment. The CAMB3LYP functional had the best performance on these compounds of the functionals tested. However, our comprehensive analysis has shown that quantitative prediction of hyperpolarizabilities is still a challenge, hampered by inadequate functionals, basis sets, and solvation models, requiring further experimental characterization. Attachment of the Au{sub 2}S group to molecules already known for their relatively large NLO properties was found to further enhance the response. While our calculations show a modest enhancement for the first hyperpolarizability, the enhancement of the second hyperpolarizability is predicted to be more than an order of magnitude.

  4. 43 CFR 3602.12 - How does the mineral materials sales process affect other users of the same public lands?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... process affect other users of the same public lands? 3602.12 Section 3602.12 Public Lands: Interior... does the mineral materials sales process affect other users of the same public lands? (a) When BLM..., entry, or other conflicting use of the land, including subsequent mining claim locations. (b)...

  5. 43 CFR 3602.12 - How does the mineral materials sales process affect other users of the same public lands?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... process affect other users of the same public lands? 3602.12 Section 3602.12 Public Lands: Interior... does the mineral materials sales process affect other users of the same public lands? (a) When BLM..., entry, or other conflicting use of the land, including subsequent mining claim locations. (b)...

  6. 43 CFR 3602.12 - How does the mineral materials sales process affect other users of the same public lands?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... process affect other users of the same public lands? 3602.12 Section 3602.12 Public Lands: Interior... does the mineral materials sales process affect other users of the same public lands? (a) When BLM..., entry, or other conflicting use of the land, including subsequent mining claim locations. (b)...

  7. Effects of tissue preservation temperature on high strain-rate material properties of brain.

    PubMed

    Zhang, Jiangyue; Yoganandan, Narayan; Pintar, Frank A; Guan, Yabo; Shender, Barry; Paskoff, Glenn; Laud, Purushottam

    2011-02-01

    Postmortem preservation conditions may be one of factors contributing to wide material property variations in brain tissues in literature. The objective of present study was to determine the effects of preservation temperatures on high strain-rate material properties of brain tissues using the split Hopkinson pressure bar (SHPB). Porcine brains were harvested immediately after sacrifice, sliced into 2 mm thickness, preserved in ice cold (group A, 10 samples) and 37°C (group B, 9 samples) saline solution and warmed to 37°C just prior to the test. A SHPB with tube aluminum transmission bar and semi-conductor strain gauges were used to enhance transmitted wave signals. Data were gathered using a digital acquisition system and processed to obtain stress-strain curves. All tests were conducted within 4 h postmortem. The mean strain-rate was 2487±72 s(-1). A repeated measures model with specimen-level random effects was used to analyze log transformed stress-strain responses through the entire loading range. The mean stress-strain curves with ±95% confidence bands demonstrated typical power relationships with the power value of 2.4519 (standard error, 0.0436) for group A and 2.2657 (standard error, 0.0443) for group B, indicating that responses for the two groups are significantly different. Stresses and tangent moduli rose with increasing strain levels in both groups. These findings indicate that storage temperatures affected brain tissue material properties and preserving tissues at 37°C produced a stiffer response at high strain-rates. Therefore, it is necessary to incorporate material properties obtained from appropriately preserved tissues to accurately predict the responses of brain using stress analyses models, such as finite element simulations. PMID:21055756

  8. An investigation of the influence of the core material properties on the compression and properties of dry-coated tablets.

    PubMed

    Thomas, W I; Rowley, G; Doveston, G

    1998-10-01

    The effect of core material properties on the process of compression and physical properties of compression-coated tablets were investigated using microcrystalline cellulose as the coating material (mantle). Three model core materials: borosilicate glass, silicone rubber, and steel, each of different Young's modulus, were selected to give a range of core mechanical properties. Coated tablets were prepared using a single-punch press, with facilities for monitoring the compression cycle and analysis of data using the Heckel (1) equation. This analysis showed a considerable effect of different core materials on the compression process, (i) as an unanchored core, and (ii) due to core material type with differing Young's modulus. PMID:9876552

  9. Radiological properties of a wax-gypsum compensator material

    SciTech Connect

    Plessis, F.C.P. du; Willemse, C.A.

    2005-05-01

    In this paper the radiological properties of a compensator material consisting of wax and gypsum is presented. Effective attenuation coefficients (EACs) have been determined from transmission measurements with an ion chamber in a Perspex phantom. Measurements were made at 80 and 100 cm source-to-skin distance (SSD) for beam energies of 6, 8, and 15 MV, for field sizes ranging from narrow beam geometries up to 40x40 cm{sup 2}, and at measurement depths of maximum dose build-up, 5 and 10 cm. A parametrization equation could be constructed to predict the EAC values within 4% uncertainty as a function of field size and depth of measurement. The EAC dependence on off-axis position was also quantified at each beam energy and SSD. It was found that the compensator material reduced the required thickness for compensation by 26% at 8 MV when compared to pure paraffin wax for a 10x10 cm{sup 2} field. Relative surface ionization (RSI) measurements have been made to quantify the effect of scattered electrons from the wax-gypsum compensator. Results indicated that for 80 cm SSD the RSI would exceed 50% for fields larger than 15x15 cm{sup 2}. At 100 cm SSD the RSI values were below 50% for all field sizes used.

  10. Optimizing material properties of composite plates for sound transmission problem

    NASA Astrophysics Data System (ADS)

    Tsai, Yu-Ting; Pawar, S. J.; Huang, Jin H.

    2015-01-01

    To calculate the specific transmission loss (TL) of a composite plate, the conjugate gradient optimization method is utilized to estimate and optimize material properties of the composite plate in this study. For an n-layer composite plate, a nonlinear dynamic stiffness matrix based on the thick plate theory is formulated. To avoid huge computational efforts due to the combination of different composite material plates, a transfer matrix approach is proposed to restrict the dynamic stiffness matrix of the composite plate to a 4×4 matrix. Moreover, the transfer matrix approach has also been used to simplify the complexity of the objective function gradient for the optimization method. Numerical simulations are performed to validate the present algorithm by comparing the TL of the optimal composite plate with that of the original plate. Small number of iterations required during convergence tests illustrates the efficiency of the optimization method. The results indicate that an excellent estimation for the composite plate can be obtained for the desired sound transmission.

  11. Material Properties of the Human Lumbar Facet Joint Capsule

    PubMed Central

    Little, Jesse S.; Khalsa, Partap S.

    2005-01-01

    The human facet joint capsule is one of the structures in the lumbar spine that constrains motions of vertebrae during global spine loading (e.g., physiological flexion). Computational models of the spine have not been able to include accurate nonlinear and viscoelastic material properties, as they have not previously been measured. Capsules were tested using a uniaxial ramp-hold protocol or a haversine displacement protocol using a commercially available materials testing device. Plane strain was measured optically. Capsules were tested both parallel and perpendicular to the dominant orientation of the collagen fibers in the capsules. Viscoelastic material properties were determined. Parallel to the dominant orientation of the collagen fibers, the complex modulus of elasticity was E* = 1.63MPa, with a storage modulus of E′ = 1.25MPa and a loss modulus of: E″ = 0.39MPa. The mean stress relaxation rates for static and dynamic loading were best fit with first-order polynomials: B (ɛ) = 0.1110 ɛ − 0.0733 and B (ɛ) = −0.1249ɛ 11794-8181 +0.0190, respectively. Perpendicular to the collagen fiber orientation, the viscous and elastic secant moduli were 1.81 and 1.00 MPa, respectively. The mean stress relaxation rate for static loading was best fit with a first-order polynomial: B (ɛ) = − 0.04ɛ − 0.06. Capsule strength parallel and perpendicular to collagen fiber orientation was 1.90 and 0.95 MPa, respectively, and extensibility was 0.65 and 0.60, respectively. Poisson’s ratio parallel and perpendicular to fiber orientation was 0.299 and 0.488, respectively. The elasticity moduli were nonlinear and anisotropic, and capsule strength was larger aligned parallel to the collagen fibers. The phase lag between stress and strain increased with haversine frequency, but the storage modulus remained large relative to the complex modulus. The stress relaxation rate was strain dependent parallel to the collagen fibers, but was strain independent perpendicularly

  12. The spectral and physical properties of metal in meteorite assemblages - Implications of asteroid surface materials

    NASA Technical Reports Server (NTRS)

    Gaffey, M. J.

    1986-01-01

    One of the objectives of the present paper is related to a definition of the spectral contribution of the nickel-iron metal component in meteoritic assemblages. Another objective is the elucidation of the chemical, physical, and petrographic properties of the metal grains which affect the spectral signature in asteroid surface materials. It is pointed out that an improved understanding of the spectral and physical properties of metal in asteroid regoliths should permit an improved characterization of these objects, and, in particular, a better evaluation of the differentiated or undifferentiated nature of the S-type and M-type asteroids. Attention is given to the spectra of iron and nickel-iron metals, the spectral effects of metal in chondritic assemblages, the spectral reflectance of metal grains in ordinary chondrites, the nature of the surfaces of chondritic metal grains, the origin of coats on chondritic metal grains, and the fragmentation of metal on asteroid surfaces.

  13. Mechanical Properties and Microstructural Evolution of Simulated Heat-Affected Zones in Wrought Eglin Steel

    NASA Astrophysics Data System (ADS)

    Leister, Brett M.; DuPont, John N.; Watanabe, Masashi; Abrahams, Rachel A.

    2015-12-01

    A comprehensive study was performed to correlate the mechanical properties and microstructural evolution in the heat-affected zone of Eglin steel. A Gleeble 3500 thermo-mechanical simulator was used to simulate weld thermal cycles with different peak temperatures at a heat input of 1500 J/mm. These samples underwent mechanical testing to determine strength and toughness in the as-welded and post-weld heat-treated conditions. The inter-critical heat-affected zone (HAZ) had the lowest strength following thermal simulation, while the fine-grain and coarse-grain heat-affected zone exhibited increased strength when compared to the inter-critical HAZ. The toughness of the heat-affected zone in the as-simulated condition is lower than that of the base metal in all regions of the HAZ. Post-weld heat treatments (PWHTs) increased the toughness of the HAZ, but at the expense of strength. In addition, certain combinations of PWHTs within specific HAZ regions exhibited low toughness caused by tempered martensite embrittlement or intergranular failure. Synchrotron X-ray diffraction data have shown that Eglin steel has retained austenite in the fine-grain HAZ in the as-simulated condition. In addition, alloy carbides (M23C6, M2C, M7C3) have been observed in the diffraction spectra for the fine-grain and coarse-grain HAZ following a PWHT of 973 K (700 °C)/4 hours.

  14. Interactions between organisms and parent materials of a constructed Technosol shape its hydrostructural properties

    NASA Astrophysics Data System (ADS)

    Deeb, M.; Grimaldi, M.; Lerch, T. Z.; Pando, A.; Gigon, A.; Blouin, M.

    2015-12-01

    Constructed Technosols provide an opportunity to recycle urban waste, and are an alternative to the uptake of topsoil from the countryside. Despite potential problems of erosion, compaction or water holding capacity, their physical properties and the resulting water regulation services are poorly documented. In a laboratory experiment, excavated deep horizons of soils and green waste compost (GWC) were mixed at six levels of GWC (from 0 to 50 %). Each mixture was set up in the presence/absence of plants and/or earthworms, in a full factorial design (n = 96). After 21 weeks, hydrostructural properties of constructed Technosols were characterized by soil shrinkage curves. Organisms explained the variance of hydrostructural characteristics (19 %) a little better than parent-material composition (14 %). The interaction between the effects of organisms and parent-material composition explained the variance far better (39 %) than each single factor. To summarize, compost and plants played a positive role in increasing available water in macropores and micropores; plants were extending the positive effect of compost up to 40 and 50 % GWC. Earthworms affected the void ratio for mixtures from 0 to 30 % GWC and available water in micropores, not in macropores. Earthworms also acted synergistically with plants by increasing their root biomass and the resulting positive effects on available water in macropores. Organisms and their interaction with parent materials thus positively affected the hydro-structural properties of constructed Technosols, with potential positive consequences on resistance to drought or compaction. Considering organisms when creating Technosols could be a promising approach to improve their fertility.

  15. How Genetics Might Affect Real Property Rights: Currents in Contemporary Bioethics.

    PubMed

    Rothstein, Mark A; Rothstein, Laura

    2016-03-01

    New developments in genetics could affect a variety of real property rights. Mortgage lenders, mortgage insurers, real estate sellers, senior living centers, retirement communities, or other parties in residential real estate transactions begin requiring predictive genetic information as part of the application process. One likely use would be by retirement communities to learn an individual's genetic risk for Alzheimer's disease. The federal Fair Housing Act prohibits discrimination based on disability, but it is not clear that it would apply to genetic risk assessments. Only California law explicitly applies to this situation and there have been no reported cases. PMID:27256137

  16. Dielectric properties of pharmaceutical materials relevant to microwave processing: effects of field frequency, material density, and moisture content.

    PubMed

    Heng, Paul W S; Loh, Z H; Liew, Celine V; Lee, C C

    2010-02-01

    The rising popularity of microwaves for drying, material processing and quality sensing has fuelled the need for knowledge concerning dielectric properties of common pharmaceutical materials. This article represents one of the few reports on the density and moisture content dependence of the dielectric properties of primary pharmaceutical materials and their relevance to microwave-assisted processing. Dielectric constants (epsilon') and losses (epsilon'') of 13 pharmaceutical materials were measured over a frequency range of 1 MHz-1 GHz at 23 +/- 1 degrees C using a parallel-electrode measurement system. Effects of field frequency, material density and moisture content on dielectric properties were studied. Material dielectric properties varied considerably with frequency. At microwave frequencies, linear relationships were established between cube-root functions of the dielectric parameters [symbols: see text] and density which enabled dielectric properties of materials at various densities to be estimated by regression. Moisture content was the main factor that contributed to the disparities in dielectric properties and heating capabilities of the materials in a laboratory microwave oven. The effectiveness of a single frequency density-independent dielectric function for moisture sensing applications was explored and found to be suitable within low ranges of moisture contents for a model material. PMID:19708060

  17. Linking Material Properties and Microstructures to Characterize Damage Associated with an Underground Explosion in Granite

    NASA Astrophysics Data System (ADS)

    Wilson, J. E.; Broome, S.; Sussman, A. J.; Townsend, M.; Schultz-Fellenz, E. S.

    2013-12-01

    The Source Physics Experiment, conducted in granite in Nevada, is a series of explosive tests designed to study the generation and propagation of seismic waves. Extensive seismic monitoring and site rock characterization are being used to improve the predictive capability of models for detecting and characterizing underground explosions. Site rock characterization includes geomechanical and material properties testing, core-scale fracture identification, and optical microscopy studies. Geomechanical and material properties determined via laboratory testing of the site rocks include unconfined compressive strength, Young's modulus, Poisson's ratio, and bulk density. Detailed fracture mapping and characterization of meso- and micro-scale fractures in recovered cores are being conducted and include mineralization changes and the extent of crushed or fractured zone away from the source. We report on the analysis of microfractures in these cores, which provide a detailed and quantitative dataset on the extent and nature of damage in the recovered cores. Microfracture density and character (open, sealed, healed) are recorded in order to differentiate sets of microfractures associated with explosive tests. Densities (mf/mm) of open microfractures correlate with source-related damage, and increase from pre- to post-test samples. Microfracture densities are affected by pre-existing fractures, depending on fracture-zone mineralogy and alteration. These microfracture density data, linked to the bulk material properties, geomechanical properties, and the structural features of the rock at the core-scale, define a damage zone surrounding the source at depth. This link is essential to understanding how the bulk material properties manifest themselves in the rock and how that might affect energy propagation. Work by Los Alamos National Laboratory was sponsored by the National Nuclear Security Administration Award No. DE-AC52-06NA25946/NST10-NCNS-PD00. Work by National Security

  18. Fractal Scaling of Particle Size Distribution and Relationships with Topsoil Properties Affected by Biological Soil Crusts

    PubMed Central

    Gao, Guang-Lei; Ding, Guo-Dong; Wu, Bin; Zhang, Yu-Qing; Qin, Shu-Gao; Zhao, Yuan-Yuan; Bao, Yan-Feng; Liu, Yun-Dong; Wan, Li; Deng, Ji-Feng

    2014-01-01

    Background Biological soil crusts are common components of desert ecosystem; they cover ground surface and interact with topsoil that contribute to desertification control and degraded land restoration in arid and semiarid regions. Methodology/Principal Findings To distinguish the changes in topsoil affected by biological soil crusts, we compared topsoil properties across three types of successional biological soil crusts (algae, lichens, and mosses crust), as well as the referenced sandland in the Mu Us Desert, Northern China. Relationships between fractal dimensions of soil particle size distribution and selected soil properties were discussed as well. The results indicated that biological soil crusts had significant positive effects on soil physical structure (P<0.05); and soil organic carbon and nutrients showed an upward trend across the successional stages of biological soil crusts. Fractal dimensions ranged from 2.1477 to 2.3032, and significantly linear correlated with selected soil properties (R2 = 0.494∼0.955, P<0.01). Conclusions/Significance Biological soil crusts cause an important increase in soil fertility, and are beneficial to sand fixation, although the process is rather slow. Fractal dimension proves to be a sensitive and useful index for quantifying changes in soil properties that additionally implies desertification. This study will be essential to provide a firm basis for future policy-making on optimal solutions regarding desertification control and assessment, as well as degraded ecosystem restoration in arid and semiarid regions. PMID:24516668

  19. Growth, Optical Properties, and Optimization of Infrared Optoelectronic Materials

    NASA Astrophysics Data System (ADS)

    Webster, Preston Thomas

    High-performance III-V semiconductors based on ternary alloys and superlattice systems are fabricated, studied, and compared for infrared optoelectronic applications. InAsBi is a ternary alloy near the GaSb lattice constant that is not as thoroughly investigated as other III-V alloys and that is challenging to produce as Bi has a tendency to surface segregate and form droplets during growth rather than incorporate. A growth window is identified within which high-quality droplet-free bulk InAsBi is produced and Bi mole fractions up to 6.4% are obtained. Photoluminescence with high internal quantum efficiency is observed from InAs/InAsBi quantum wells. The high structural and optical quality of the InAsBi materials examined demonstrates that bulk, quantum well, and superlattice structures utilizing InAsBi are an important design option for efficient infrared coverage. Another important infrared material system is InAsSb and the strain-balanced InAs/InAsSb superlattice on GaSb. Detailed examination of X-ray diffraction, photoluminescence, and spectroscopic ellipsometry data provides the temperature and composition dependent bandgap of bulk InAsSb. The unintentional incorporation of approximately 1% Sb into the InAs layers of the superlattice is measured and found to significantly impact the analysis of the InAs/InAsSb band alignment. In the analysis of the absorption spectra, the ground state absorption coefficient and transition strength of the superlattice are proportional to the square of the electron-hole wavefunction overlap; wavefunction overlap is therefore a major design parameter in terms of optimizing absorption in these materials. Furthermore in addition to improvements through design optimization, the optical quality of the materials studied is found to be positively enhanced with the use of Bi as a surfactant during molecular beam epitaxy growth. A software tool is developed that calculates and optimizes the miniband structure of semiconductor

  20. Review of materials property data for nondestructive characterization of pipeline materials

    NASA Astrophysics Data System (ADS)

    Smart, Lucinda Jeanette

    The oil and gas industry relies on an aging infrastructure of pipeline for transportation and distribution of product; therefore, it is important to assess the condition of the pipeline, using accurate material and mechanical properties, to ensure failures are minimized. Nondestructive evaluation techniques are currently being used to assess pipeline, but necessary mechanical properties (yield strength, tensile strength, fracture toughness, and ductile-to-brittle transition temperature) are not yet able to be adequately characterized by these methods. There are many issues to consider when addressing this problem. There is variability within the manufacturing processes due to simple inaccuracies in the processes themselves, and changes in practices over the years. There is also variability in the destructive techniques used for assessment of mechanical properties before the pipe is put into service. Current focus in the industry tends to be on pipe installed in the 1950's and 1960's because about half of the pipe currently in service was installed during these time periods, but it is equally important to verify the properties of modern pipe Therefore, nondestructive methods of measurement are commonly used for determining defect severity (e.g. magnetic flux leakage and ultrasonic) are being explored to determine what other properties can be measured to relate to mechanical properties. For future activities, it is advised to compare the accuracies of both destructive and nondestructive methods of determining properties, should some method of nondestructive evaluation become a more viable technique for mechanical property measurements, either directly or indirectly. The relationships between what can be measured (chemical content, grain size, microstructure, hardness, coercivity, permeability, etc) and the mechanical properties desired listed previously, show that there is a strong relationship between hardness and yield strength. This is already well known in the

  1. Assembling and properties of the polymer-particle nanostructured materials

    NASA Astrophysics Data System (ADS)

    Sheparovych, Roman

    Complementary properties of the soft and hard matter explain its common encounter in many natural and manmade applications. A combination of flexible organic macromolecules and hard mineral clusters results in new materials far advantageous than its constituents alone. In this work we study assembling of colloidal nanocrystals and polymers into complex nanostructures. Magnetism, surface wettability and adhesion comprise properties of interest for the obtained nanocomposites. Applying a magnetic field induces a reversible 1D ordering of the magnetically susceptible particles. This property was employed in the fabrication of the permanent chains of magnetite nanocrystals (d=15nm). In the assembling process the aligned particles were bound together using polyelectrolyte macromolecules. The basics of the binding process involved an electrostatic interaction between the positively charged polyelectrolyte and the negative surface of the particles (aqueous environment). Adsorption of the polymer molecules onto several adjacent particles in the aligned 1D aggregate results in the formation of the permanent particulate chains. Positive charges of the adsorbed polyelectrolyte molecules stabilize the dispersion of the obtained nanostructures in water. Magnetization measurements revealed that superparamagnetic nanoparticles, being assembled into 1D ordered structures, attain magnetic coercivity. This effect originates from the magnetostatic interaction between the neighboring magnetite nanocrystals. The preferable dipole alignment of the assembled nanoparticles is directed along the chain axis. Another system studied in this project includes polymer-particle responsive surface coatings. Tethered polymer chains and particles bearing different functionalities change surface properties upon restructuring of the composite layer. When the environment favors polymer swelling (good solvent), the polymer chains segregate to the surface and cover the particles. In the opposite case

  2. Colour and Optical Properties of Materials: An Exploration of the Relationship Between Light, the Optical Properties of Materials and Colour

    NASA Astrophysics Data System (ADS)

    Tilley, Richard J. D.

    2003-05-01

    Colour is an important and integral part of everyday life, and an understanding and knowledge of the scientific principles behind colour, with its many applications and uses, is becoming increasingly important to a wide range of academic disciplines, from physical, medical and biological sciences through to the arts. Colour and the Optical Properties of Materials carefully introduces the science behind the subject, along with many modern and cutting-edge applications, chose to appeal to today's students. For science students, it provides a broad introduction to the subject and the many applications of colour. To more applied students, such as engineering and arts students, it provides the essential scientific background to colour and the many applications. Features: * Introduces the science behind the subject whilst closely connecting it to modern applications, such as colour displays, optical amplifiers and colour centre lasers * Richly illustrated with full-colour plates * Includes many worked examples, along with problems and exercises at the end of each chapter and selected answers at the back of the book * A Web site, including additional problems and full solutions to all the problems, which may be accessed at: www.cardiff.ac.uk/uwcc/engin/staff/rdjt/colour Written for students taking an introductory course in colour in a wide range of disciplines such as physics, chemistry, engineering, materials science, computer science, design, photography, architecture and textiles.

  3. Stress effects on the elastic properties of amorphous polymeric materials

    SciTech Connect

    Caponi, S. E-mail: silvia.corezzi@unipg.it; Fioretto, D.

    2014-12-07

    Brillouin light scattering measurements have been used to study the stress induced modification in the elastic properties of two glass forming polymers: polybutadiene and epoxy-amine resin, prototypes of linear and network polymers, respectively. Following the usual thermodynamic path to the glass transition, polybutadiene has been studied as a function of temperature from the liquid well into the glassy phase. In the epoxy resin, the experiments took advantage of the system ability to reach the glass both via the chemical vitrification route, i.e., by increasing the number of covalent bonds among the constituent molecules, as well as via the physical thermal route, i.e., by decreasing the temperature. Independently from the particular way chosen to reach the glassy phase, the measurements reveal the signature of long range tensile stresses development in the glass. The stress presence modifies both the value of the sound velocities and their mutual relationship, so as to break the generalized Cauchy-like relation. In particular, when long range stresses, by improvise sample cracking, are released, the frequency of longitudinal acoustic modes increases more than 10% in polybutadiene and ∼4% in the epoxy resin. The data analysis suggests the presence of at least two different mechanisms acting on different length scales which strongly affect the overall elastic behaviour of the systems: (i) the development of tensile stress acting as a negative pressure and (ii) the development of anisotropy which increases its importance deeper and deeper in the glassy state.

  4. Stress effects on the elastic properties of amorphous polymeric materials

    NASA Astrophysics Data System (ADS)

    Caponi, S.; Corezzi, S.; Mattarelli, M.; Fioretto, D.

    2014-12-01

    Brillouin light scattering measurements have been used to study the stress induced modification in the elastic properties of two glass forming polymers: polybutadiene and epoxy-amine resin, prototypes of linear and network polymers, respectively. Following the usual thermodynamic path to the glass transition, polybutadiene has been studied as a function of temperature from the liquid well into the glassy phase. In the epoxy resin, the experiments took advantage of the system ability to reach the glass both via the chemical vitrification route, i.e., by increasing the number of covalent bonds among the constituent molecules, as well as via the physical thermal route, i.e., by decreasing the temperature. Independently from the particular way chosen to reach the glassy phase, the measurements reveal the signature of long range tensile stresses development in the glass. The stress presence modifies both the value of the sound velocities and their mutual relationship, so as to break the generalized Cauchy-like relation. In particular, when long range stresses, by improvise sample cracking, are released, the frequency of longitudinal acoustic modes increases more than 10% in polybutadiene and ˜4% in the epoxy resin. The data analysis suggests the presence of at least two different mechanisms acting on different length scales which strongly affect the overall elastic behaviour of the systems: (i) the development of tensile stress acting as a negative pressure and (ii) the development of anisotropy which increases its importance deeper and deeper in the glassy state.

  5. Stress effects on the elastic properties of amorphous polymeric materials.

    PubMed

    Caponi, S; Corezzi, S; Mattarelli, M; Fioretto, D

    2014-12-01

    Brillouin light scattering measurements have been used to study the stress induced modification in the elastic properties of two glass forming polymers: polybutadiene and epoxy-amine resin, prototypes of linear and network polymers, respectively. Following the usual thermodynamic path to the glass transition, polybutadiene has been studied as a function of temperature from the liquid well into the glassy phase. In the epoxy resin, the experiments took advantage of the system ability to reach the glass both via the chemical vitrification route, i.e., by increasing the number of covalent bonds among the constituent molecules, as well as via the physical thermal route, i.e., by decreasing the temperature. Independently from the particular way chosen to reach the glassy phase, the measurements reveal the signature of long range tensile stresses development in the glass. The stress presence modifies both the value of the sound velocities and their mutual relationship, so as to break the generalized Cauchy-like relation. In particular, when long range stresses, by improvise sample cracking, are released, the frequency of longitudinal acoustic modes increases more than 10% in polybutadiene and ∼4% in the epoxy resin. The data analysis suggests the presence of at least two different mechanisms acting on different length scales which strongly affect the overall elastic behaviour of the systems: (i) the development of tensile stress acting as a negative pressure and (ii) the development of anisotropy which increases its importance deeper and deeper in the glassy state. PMID:25481163

  6. Hyperelastic Material Properties of Mouse Skin under Compression.

    PubMed

    Wang, Yuxiang; Marshall, Kara L; Baba, Yoshichika; Gerling, Gregory J; Lumpkin, Ellen A

    2013-01-01

    The skin is a dynamic organ whose complex material properties are capable of withstanding continuous mechanical stress while accommodating insults and organism growth. Moreover, synchronized hair cycles, comprising waves of hair growth, regression and rest, are accompanied by dramatic fluctuations in skin thickness in mice. Whether such structural changes alter skin mechanics is unknown. Mouse models are extensively used to study skin biology and pathophysiology, including aging, UV-induced skin damage and somatosensory signaling. As the skin serves a pivotal role in the transfer function from sensory stimuli to neuronal signaling, we sought to define the mechanical properties of mouse skin over a range of normal physiological states. Skin thickness, stiffness and modulus were quantitatively surveyed in adult, female mice (Mus musculus). These measures were analyzed under uniaxial compression, which is relevant for touch reception and compression injuries, rather than tension, which is typically used to analyze skin mechanics. Compression tests were performed with 105 full-thickness, freshly isolated specimens from the hairy skin of the hind limb. Physiological variables included body weight, hair-cycle stage, maturity level, skin site and individual animal differences. Skin thickness and stiffness were dominated by hair-cycle stage at young (6-10 weeks) and intermediate (13-19 weeks) adult ages but by body weight in mature mice (26-34 weeks). Interestingly, stiffness varied inversely with thickness so that hyperelastic modulus was consistent across hair-cycle stages and body weights. By contrast, the mechanics of hairy skin differs markedly with anatomical location. In particular, skin containing fascial structures such as nerves and blood vessels showed significantly greater modulus than adjacent sites. Collectively, this systematic survey indicates that, although its structure changes dramatically throughout adult life, mouse skin at a given location maintains a

  7. Hyperelastic Material Properties of Mouse Skin under Compression

    PubMed Central

    Wang, Yuxiang; Marshall, Kara L.; Baba, Yoshichika; Gerling, Gregory J.; Lumpkin, Ellen A.

    2013-01-01

    The skin is a dynamic organ whose complex material properties are capable of withstanding continuous mechanical stress while accommodating insults and organism growth. Moreover, synchronized hair cycles, comprising waves of hair growth, regression and rest, are accompanied by dramatic fluctuations in skin thickness in mice. Whether such structural changes alter skin mechanics is unknown. Mouse models are extensively used to study skin biology and pathophysiology, including aging, UV-induced skin damage and somatosensory signaling. As the skin serves a pivotal role in the transfer function from sensory stimuli to neuronal signaling, we sought to define the mechanical properties of mouse skin over a range of normal physiological states. Skin thickness, stiffness and modulus were quantitatively surveyed in adult, female mice (Mus musculus). These measures were analyzed under uniaxial compression, which is relevant for touch reception and compression injuries, rather than tension, which is typically used to analyze skin mechanics. Compression tests were performed with 105 full-thickness, freshly isolated specimens from the hairy skin of the hind limb. Physiological variables included body weight, hair-cycle stage, maturity level, skin site and individual animal differences. Skin thickness and stiffness were dominated by hair-cycle stage at young (6–10 weeks) and intermediate (13–19 weeks) adult ages but by body weight in mature mice (26–34 weeks). Interestingly, stiffness varied inversely with thickness so that hyperelastic modulus was consistent across hair-cycle stages and body weights. By contrast, the mechanics of hairy skin differs markedly with anatomical location. In particular, skin containing fascial structures such as nerves and blood vessels showed significantly greater modulus than adjacent sites. Collectively, this systematic survey indicates that, although its structure changes dramatically throughout adult life, mouse skin at a given location

  8. Synthesis, characterization, and properties of low-dimensional nanostructured materials

    NASA Astrophysics Data System (ADS)

    Hu, Xianluo

    2007-05-01

    Nanometer scale structures represent an exciting and rapidly expanding area of research. Studies on new physical/chemical properties and applications of nanomaterials and nanostructures are possible only when nanostructured materials are made available with desired size, morphology, crystal and microstructure, and composition. Thus, controlled synthesis of nanomaterials is the essential aspect of nanotechnology. This thesis describes the development of simple and versatile solution-based approaches to synthesize low-dimensional nanostructures. The first major goal of this research is to design and fabricate morphology-controlled alpha-Fe 2O3 nanoarchitectures in aqueous solution through a programmed microwave-assisted hydrothermal route, taking advantage of microwave irradiation and hydrothermal effects. Free-standing alpha-Fe2O3 nanorings are prepared by hydrolysis of FeCl3 in the presence of phosphate ions. The as-formed architecture of alpha-Fe2O 3 nanorings is an exciting new member in the family of iron oxide nanostructures. Our preliminary results demonstrate that sensors made of the alpha-Fe 2O3 nanorings exhibit high sensitivity not only for bio-sensing of hydrogen peroxide in a physiological solution but also for gas-sensing of alcohol vapor at room temperature. Moreover, monodisperse alpha-Fe 2O3 nanocrystals with continuous aspect-ratio tuning and fine shape control are achieved by controlling the experimental conditions. The as-formed alpha-Fe2O3 exhibits shape-dependent infrared optical properties. The growth process of colloidal alpha-Fe 2O3 crystals in the presence of phosphate ions is discussed. In addition, through an efficient microwave-assisted hydrothermal process, self-assembled hierarchical alpha-Fe2O3 nanoarchitectures are synthesized on a large scale. The second major goal of this research is to develop convenient microwave-hydrothermal approaches for the fabrication of carbon-based nanocomposites: (1) A one-pot solution-phase route, namely

  9. Material properties of zooplankton and nekton from the California current

    NASA Astrophysics Data System (ADS)

    Becker, Kaylyn

    This study measured the material properties of zooplankton, Pacific hake (Merluccius productus), Humboldt squid (Dosidicus gigas), and two species of myctophids (Symbolophorus californiensis and Diaphus theta) collected from the California Current ecosystem. The density contrast (g) was measured for euphausiids, decapods (Sergestes similis), amphipods (Primno macropa, Phronima sp., and Hyperiid spp.), siphonophore bracts, chaetognaths, larval fish, crab megalopae, larval squid, and medusae. Morphometric data (length, width, and height) were collected for these taxa. Density contrasts varied within and between zooplankton taxa. The mean and standard deviation for euphausiid density contrast were 1.059 +/- 0.009. Relationships between zooplankton density contrast and morphometric measurements, geographic location, and environmental conditions were investigated. Site had a significant effect on euphausiid density contrast. Density contrasts of euphausiids collected in the same geographic area approximately 4-10 days apart were significantly higher (p < 0.001). Sound speed contrast (h) was measured for euphausiids and pelagic decapods (S. similis) and it varied between taxa. The mean and standard deviation for euphausiid sound speed were 1.019 +/- 0.009. Euphausiid mass was calculated from density measurements and volume, and a relationship between euphausiid mass and length was produced. We determined that euphausiid from volumes could be accurately estimated two dimensional measurements of animal body shape, and that biomass (or biovolume) could be accurately calculated from digital photographs of animals. Density contrast (g) was measured for zooplankton, pieces of hake flesh, myctophid flesh, and of the following Humboldt squid body parts: mantle, arms, tentacle, braincase, eyes, pen, and beak. The density contrasts varied within and between fish taxa, as well as among squid body parts. Effects of animal length and environmental conditions on nekton density

  10. Optical Properties of Doped Cuprates and Related Materials

    NASA Astrophysics Data System (ADS)

    Yoon, Young-Duck

    1995-01-01

    The optical properties of cuprates, rm Nd_{2-it x}Ce_{it x}CuO_4 and rm La_ {2-it x}Sr_{it x}CuO _4, and the related materials, rm Ba_{1-it x}K_{it x}BiO_3 (BKBO) and rm BaPb_{1-it x}Bi_{1- it x}O_3 (BPBO), have been extensively investigated by doping- and temperature-dependent reflectance measurement of single crystal samples in the frequency range between 30 cm^{-1} (4 meV) and 40 000 cm^{-1} (5 eV). The rm Nd_{2-it x}Ce_{it x}CuO_4 system has been studied at Ce compositions in the range 0 <=q x <=q 0.2. rm La_{2-it x}Sr_{it x}CuO_4 has been studied in the spin glass doping regime, (x <=q 0.04). The two bismuthates have been investigated as superconducting materials with the maximum T_{c} . Our results for rm Nd_{2 -it x}Ce_{it x}CuO_4 show that doping with electrons induces a transfer of spectral weight from the high energy side above the charge transfer excitation band to the low energy side below 1.2 eV, similar to the results observed in hole-doped rm La_{2-it x}Sr_ {it x}CuO_4. However, the low frequency spectral weight grows slightly faster than 2x with doping x, as expected for the Mott-Hubbard model. We find very interesting results at low doping levels in rm La_{2-it x }Sr_{it x}CuO_4. Upon Sr doping the oscillator strength of the phonons is gradually reduced and doping induced modes (Raman modes and carrier-lattice interaction mode) appear in the far -infrared. We also find that the deformation potential by the dynamical tilting of CuO_6 octahedra induces a carrier-lattice interaction. The carrier -lattice interaction is characterized by strong infrared active modes and an appearance of the strong A _{g} Raman modes upon cooling. Finally, we present the normal and the superconducting properties of Bi-O superconductors. We conclude that the BKBO system is a weak- or moderate-coupling BCS-type superconductor in the dirty limit.

  11. Factors affecting the optical properties of Pd-free Au-Pt-based dental alloys.

    PubMed

    Shiraishi, Takanobu; Takuma, Yasuko; Miura, Eri; Tanaka, Yasuhiro; Hisatsune, Kunihiro

    2003-12-01

    The optical properties of experimental Au-Pt-based alloys containing a small amount of In, Sn, and Zn were investigated by spectrophotometric colorimetry to extract factors affecting color of Au-Pt-based high-karat dental alloys. It was found that the optical properties of Au-Pt-based alloys are strongly affected by the number of valence electrons per atom in an alloy, namely, the electron:atom ratio, e/a. That is, by increasing the e/a-value, activities of reflection in the long-wavelength range and absorption in the short-wavelength range in the visible spectrum apparently increased. As a result, the maximum slope of the spectral reflectance curve at the absorption edge, which is located near 515 nm (approximately 2.4 eV), apparently increased with e/a-value. Due to this effect, the b*-coordinate (yellow-blue) in the CIELAB color space considerably increased and the a*-coordinate (red-green) slightly increased with e/a-value. The addition of a third element with a higher number of valence electrons to the binary Au-Pt alloy is, therefore, effective in giving a gold tinge to the parent Au-Pt alloy. This information may be useful in controlling the color of Au-Pt-based dental alloys. PMID:15348493

  12. Molecular level materials design for improvements of actuation properties of dielectric elastomer actuators

    NASA Astrophysics Data System (ADS)

    Kofod, G.; Stoyanov, H.; Kollosche, M.; Risse, S.; Ragusch, H.; McCarthy, D. N.; Waché, R.; Rychkov, D.; Dansachmüller, M.

    2011-04-01

    Dielectric elastomer actuators are soft electro-mechanical transducers with possible uses in robotic, orthopaedic and automotive applications. The active material must be soft and have a high ability to store electrical energy. Hence, three properties of the elastic medium in a dielectric elastomer actuator affect the actuation properties directly: dielectric constant, electric breakdown strength, and mechanical stiffness. The dielectric constant of a given elastomer can be improved by mixing it with other components with a higher dielectric constant, which can be classified as insulating or conducting. In this paper, an overview of all approaches proposed so far for dielectric constant improvement in these soft materials will be provided. Insulating particles such as TiO2 nanoparticles can raise the dielectric constant, but may also lead to stiffening of the composite, such that the overall actuation is lowered. It is shown here how a chemical coating of the TiO2 nanoparticles leads to verifiable improvements. Conducting material can also lead to improvements, as has been shown in several cases. Simple percolation, relying on the random distribution of conducting nanoparticles, commonly leads to drastic lowering of the breakdown strength. On the other hand, conducting polymer can also be employed, as has been demonstrated. We show here how an approach based on a specific chemical reaction between the conducting polymer and the elastomer network molecules solves the problem of premature breakdown which is otherwise typically found.

  13. Method and apparatus for measuring properties of particle beams using thermo-resistive material properties

    DOEpatents

    Degtiarenko, Pavel V.; Dotson, Danny Wayne

    2007-10-09

    A beam position detector for measuring the properties of a charged particle beam, including the beam's position, size, shape, and intensity. One or more absorbers are constructed of thermo-resistive material and positioned to intercept and absorb a portion of the incoming beam power, thereby causing local heating of each absorber. The local temperature increase distribution across the absorber, or the distribution between different absorbers, will depend on the intensity, size, and position of the beam. The absorbers are constructed of a material having a strong dependence of electrical resistivity on temperature. The beam position detector has no moving parts in the vicinity of the beam and is especially suited to beam areas having high ionizing radiation dose rates or poor beam quality, including beams dispersed in the transverse direction and in their time radio frequency structure.

  14. The interpretation of XPS spectra: Insights into materials properties

    NASA Astrophysics Data System (ADS)

    Bagus, Paul S.; Ilton, Eugene S.; Nelin, Connie J.

    2013-06-01

    We review basic and advanced concepts needed for the correct analysis of XPS features. We place these concepts on rigorous foundations and explore their physical and chemical meanings without stressing the derivation of the mathematical formulations, which can be found in the cited literature. The significance and value of combining theory and experiment is demonstrated by discussions of the physical and chemical origins of the main and satellite XPS features for a variety of molecular and condensed phase materials. BE: binding energy. The binding energy of an electron associated with a peak in a photoelectron spectra. CI: configuration interaction. The common use is to describe many-body wavefunctions that are the mixing of several determinants for different configurations. CSF: configuration state function. A determinant or combination of determinants that is an eigenfunction of the angular momentum operators. Normally CSFs are formed for Russell-Saunders, L-S coupling but they can also be formed for j-j coupling. CT: charge transfer. Usually refers to the transfer of an electron from a ligand orbital into an unoccupied or partially occupied, metal orbital. CSOV: constrained space orbital variation. A theoretical procedure for decomposing the contributions to various properties by constraining the space of orbitals varied and the space of basis functions in which they are varied. ΔSCF: delta self-consistent field. Normally refers to the difference in the properties of two states, an initial and a final state, each determined from separate self-consistent field variations. DFT: density functional theory. DHF: Dirac-Hartree-Fock. ER: relaxation energy. Erel: relative energy. Normally of the BE of a peak relative to some reference BE taken as zero. FC: Franck-Condon. Normally used in connection with the vibrational broadening of peaks in photoemission spectra. FO: frozen orbital. Used to describe wavefunctions and other properties obtained when the orbitals of the

  15. Eutectics as improved pharmaceutical materials: design, properties and characterization.

    PubMed

    Cherukuvada, Suryanarayan; Nangia, Ashwini

    2014-01-28

    Eutectics are a long known class of multi-component solids with important and useful applications in daily life. In comparison to other multi-component crystalline solids, such as salts, solid solutions, molecular complexes and cocrystals, eutectics are less studied in terms of molecular structure organization and bonding interactions. Classically, a eutectic is defined based on its low melting point compared to the individual components. In this article, we attempt to define eutectics not just based on thermal methods but from a structural organization view point, and discuss their microstructures and properties as organic materials vis-a-vis solid solutions and cocrystals. The X-ray crystal structure of a cocrystal is different from that of the individual components whereas the unit cell of a solid solution is similar to that of one of the components. Eutectics are closer to the latter species in that their crystalline arrangement is similar to the parent components but they are different with respect to the structural integrity. A solid solution possesses structural homogeneity throughout the structure (single phase) but a eutectic is a heterogeneous ensemble of individual components whose crystal structures are like discontinuous solid solutions (phase separated). Thus, a eutectic may be better defined as a conglomerate of solid solutions. A structural analysis of cocrystals, solid solutions and eutectics has led to an understanding that materials with strong adhesive (hetero) interactions between the unlike components will lead to cocrystals whereas those having stronger cohesive (homo/self) interactions will more often give rise to solid solutions (for similar structures of components) and eutectics (for different structures of components). We demonstrate that the same crystal engineering principles which have been profitably utilized for cocrystal design in the past decade can now be applied to make eutectics as novel composite materials, illustrated by

  16. Leaf biomechanical properties in Arabidopsis thaliana polysaccharide mutants affect drought survival.

    PubMed

    Balsamo, Ronald; Boak, Merewyn; Nagle, Kayla; Peethambaran, Bela; Layton, Bradley

    2015-11-26

    Individual sugars are the building blocks of cell wall polysaccharides, which in turn comprise a plant׳s overall architectural structure. But which sugars play the most prominent role in maintaining a plant׳s mechanical stability during large cellular deformations induced by drought? We investigated the individual contributions of several genes that are involved in the synthesis of monosaccharides which are important for cell wall structure. We then measured drought tolerance and mechanical integrity during simulated drought in Arabidopsis thaliana. To assess mechanical properties, we designed a small-scale tensile tester for measuring failure strain, ultimate tensile stress, work to failure, toughness, and elastic modulus of 6-week-old leaves in both hydrated and drought-simulated states. Col-0 mutants used in this study include those deficient in lignin, cellulose, components of hemicellulose such as xylose and fucose, the pectic components arabinose and rhamnose, as well as mutants with enhanced arabinose and total pectin content. We found that drought tolerance is correlated to the mechanical and architectural stability of leaves as they experience dehydration. Of the mutants, S096418 with mutations for reduced xylose and galactose was the least drought tolerant, while the arabinose-altered CS8578 mutants were the least affected by water loss. There were also notable correlations between drought tolerance and mechanical properties in the diminished rhamnose mutant, CS8575 and the dehydrogenase-disrupted S120106. Our findings suggest that components of hemicellulose and pectins affect leaf biomechanical properties and may play an important role in the ability of this model system to survive drought. PMID:26520913

  17. Accelerated search for materials with targeted properties by adaptive design

    NASA Astrophysics Data System (ADS)

    Xue, Dezhen; Balachandran, Prasanna V.; Hogden, John; Theiler, James; Xue, Deqing; Lookman, Turab

    2016-04-01

    Finding new materials with targeted properties has traditionally been guided by intuition, and trial and error. With increasing chemical complexity, the combinatorial possibilities are too large for an Edisonian approach to be practical. Here we show how an adaptive design strategy, tightly coupled with experiments, can accelerate the discovery process by sequentially identifying the next experiments or calculations, to effectively navigate the complex search space. Our strategy uses inference and global optimization to balance the trade-off between exploitation and exploration of the search space. We demonstrate this by finding very low thermal hysteresis (ΔT) NiTi-based shape memory alloys, with Ti50.0Ni46.7Cu0.8Fe2.3Pd0.2 possessing the smallest ΔT (1.84 K). We synthesize and characterize 36 predicted compositions (9 feedback loops) from a potential space of ~800,000 compositions. Of these, 14 had smaller ΔT than any of the 22 in the original data set.

  18. Structural properties of laminated Douglas fir/epoxy composite material

    NASA Technical Reports Server (NTRS)

    Spera, David A.; Esgar, Jack B.; Gougeon, Meade; Zuteck, Michael D.

    1990-01-01

    This publication contains a compilation of static and fatigue strength data for laminated-wood material made from Douglas fir and epoxy. Results of tests conducted by several organizations are correlated to provide insight into the effects of variables such as moisture, size, lamina-to-lamina joint design, wood veneer grade, and the ratio of cyclic stress to steady stress during fatigue testing. These test data were originally obtained during development of wood rotor blades for large-scale wind turbines of the horizontal-axis (propeller) configuration. Most of the strength property data in this compilation are not found in the published literature. Test sections ranged from round cylinders 2.25 in. in diameter to rectangular slabs 6 by 24 in. in cross section and approximately 30 ft. long. All specimens were made from Douglas fir veneers 0.10 in. thick, bonded together with the WEST epoxy system developed for fabrication and repair of wood boats. Loading was usually parallel to the grain. Size effects (reduction in strength with increase in test volume) are observed in some of the test data, and a simple mathematical model is presented that includes the probability of failure. General characteristics of the wood/epoxy laminate are discussed, including features that make it useful for a wide variety of applications.

  19. Structural properties of laminated Douglas fir/epoxy composite material

    SciTech Connect

    Spera, D.A. . Lewis Research Center); Esgar, J.B. ); Gougeon, M.; Zuteck, M.D. )

    1990-05-01

    This publication contains a compilation of static and fatigue and strength data for laminated-wood material made from Douglas fir and epoxy. Results of tests conducted by several organizations are correlated to provide insight into the effects of variables such as moisture, size, lamina-to-lamina joint design, wood veneer grade, and the ratio of cyclic stress to steady stress during fatigue testing. These test data were originally obtained during development of wood rotor blades for large-scale wind turbines of the horizontal-axis (propeller) configuration. Most of the strength property data in this compilation are not found in the published literature. Test sections ranged from round cylinders 2.25 in. in diameter to rectangular slabs 6 in. by 24 in. in cross section and approximately 30 ft long. All specimens were made from Douglas fir veneers 0.10 in. thick, bonded together with the WEST epoxy system developed for fabrication and repair of wood boats. Loading was usually parallel to the grain. Size effects (reduction in strength with increase in test volume) are observed in some of the test data, and a simple mathematical model is presented that includes the probability of failure. General characteristics of the wood/epoxy laminate are discussed, including features that make it useful for a wide variety of applications. 9 refs.

  20. Accelerated search for materials with targeted properties by adaptive design.

    PubMed

    Xue, Dezhen; Balachandran, Prasanna V; Hogden, John; Theiler, James; Xue, Deqing; Lookman, Turab

    2016-01-01

    Finding new materials with targeted properties has traditionally been guided by intuition, and trial and error. With increasing chemical complexity, the combinatorial possibilities are too large for an Edisonian approach to be practical. Here we show how an adaptive design strategy, tightly coupled with experiments, can accelerate the discovery process by sequentially identifying the next experiments or calculations, to effectively navigate the complex search space. Our strategy uses inference and global optimization to balance the trade-off between exploitation and exploration of the search space. We demonstrate this by finding very low thermal hysteresis (ΔT) NiTi-based shape memory alloys, with Ti50.0Ni46.7Cu0.8Fe2.3Pd0.2 possessing the smallest ΔT (1.84 K). We synthesize and characterize 36 predicted compositions (9 feedback loops) from a potential space of ∼800,000 compositions. Of these, 14 had smaller ΔT than any of the 22 in the original data set. PMID:27079901

  1. Dynamic material properties of the pregnant human uterus.

    PubMed

    Manoogian, Sarah J; Bisplinghoff, Jill A; Kemper, Andrew R; Duma, Stefan M

    2012-06-01

    Given that automobile crashes are the largest single cause of death for pregnant females, scientists are developing advanced computer models of pregnant occupants. The purpose of this study is to quantify the dynamic material properties of the human uterus in order to increase the biofidelity of these models. A total of 19 dynamic tension tests were performed on pregnant human uterus tissues taken from six separate donors. The tissues were collected during full term Cesarean style deliveries and tested within 36 h of surgery. The tissues were processed into uniform coupon sections and tested at 1.5 strains/s using linear motors. Local stress and strain were determined from load data and optical markers using high speed video. The experiments resulted in a non-linear stress versus strain curves with an overall average peak failure true strain of 0.32±0.112 and a corresponding peak failure true stress of 656.3±483.9 kPa. These are the first data available for the dynamic response of pregnant human uterus tissues, and it is anticipated they will increase the accuracy of future pregnant female computational models. PMID:22542221

  2. Laves phase-based materials: Microstructure, deformation modes and properties

    SciTech Connect

    Kumar, K.S.

    1997-12-31

    Intermetallic compounds with the AB{sub 2} stoichiometry can exist with the C14, C15 or C36 structures, otherwise called Laves phases. In the past, single-phase Laves compounds, particularly Mg-containing binary compounds, have been examined to obtain an understanding of the dislocation structures as well as their mobility; alternately, effort has also been expended in examining the polytypic transformations that occur in such Laves phases. More recently however, Laves phases and polyphase alloys containing the Laves phase have been examined with the intent of developing structural alloys for elevated temperature applications. Specifically, alloys based on the Cr-Group IV (Ti, Zr, Hf) and Group V (Nb, Ta) elements as well as the ternary V-Hf-Nb system have been the focus of several investigations. Physical and mechanical properties have been measured, and microstructure has been characterized as a function of heat treatment. Deformation modes have been re-examined in detail. New ideas based on synchroshear have been put forth to explain the polytypic transformations that occur in these systems, and have been extended to also explain twinning and slip. Earlier observations are first summarized and then these recent advances are reviewed and the potential for these materials is assessed. 57 refs., 8 figs.

  3. The analytical representation of viscoelastic material properties using optimization techniques

    NASA Technical Reports Server (NTRS)

    Hill, S. A.

    1993-01-01

    This report presents a technique to model viscoelastic material properties with a function of the form of the Prony series. Generally, the method employed to determine the function constants requires assuming values for the exponential constants of the function and then resolving the remaining constants through linear least-squares techniques. The technique presented here allows all the constants to be analytically determined through optimization techniques. This technique is employed in a computer program named PRONY and makes use of commercially available optimization tool developed by VMA Engineering, Inc. The PRONY program was utilized to compare the technique against previously determined models for solid rocket motor TP-H1148 propellant and V747-75 Viton fluoroelastomer. In both cases, the optimization technique generated functions that modeled the test data with at least an order of magnitude better correlation. This technique has demonstrated the capability to use small or large data sets and to use data sets that have uniformly or nonuniformly spaced data pairs. The reduction of experimental data to accurate mathematical models is a vital part of most scientific and engineering research. This technique of regression through optimization can be applied to other mathematical models that are difficult to fit to experimental data through traditional regression techniques.

  4. Accelerated search for materials with targeted properties by adaptive design

    PubMed Central

    Xue, Dezhen; Balachandran, Prasanna V.; Hogden, John; Theiler, James; Xue, Deqing; Lookman, Turab

    2016-01-01

    Finding new materials with targeted properties has traditionally been guided by intuition, and trial and error. With increasing chemical complexity, the combinatorial possibilities are too large for an Edisonian approach to be practical. Here we show how an adaptive design strategy, tightly coupled with experiments, can accelerate the discovery process by sequentially identifying the next experiments or calculations, to effectively navigate the complex search space. Our strategy uses inference and global optimization to balance the trade-off between exploitation and exploration of the search space. We demonstrate this by finding very low thermal hysteresis (ΔT) NiTi-based shape memory alloys, with Ti50.0Ni46.7Cu0.8Fe2.3Pd0.2 possessing the smallest ΔT (1.84 K). We synthesize and characterize 36 predicted compositions (9 feedback loops) from a potential space of ∼800,000 compositions. Of these, 14 had smaller ΔT than any of the 22 in the original data set. PMID:27079901

  5. Transport Properties of Nanoscale Materials by First-principles Calculations

    NASA Astrophysics Data System (ADS)

    Mizuseki, Hiroshi; Belosludov, Rodion V.; Lee, S.-U.; Kawazoe, Yoshiyuki

    2009-03-01

    Molecular devices are potential candidates for the next step towards nanoelectronic technology. Our group has covered a wide range of nanoscale wires, which have potential application in molecular electronics using first-principles calculations and nonequilibrium Green's function formalism [1]. Our target materials are supramolecular enamel wires (covered wires) [2], connection between organic molecules and metal electrodes, self-assembled nanowires on silicon surface [3], porphyrin [4], phthalocyanine, metallocene [5], fused-ring thiophene molecules, length dependence of conductance in alkanedithiols and so on. Namely, we have investigated a relationship of the energy levels of delocalized frontier orbitals (HOMO and LUMO) and Fermi level of metal electrodes and estimate the electronic transport properties through atomic and molecular wires using Green's function approach. References [1] http://www-lab.imr.edu/˜mizuseki/nanowire.html [2] R. V. Belosludov, A. A. Farajian, H. Baba, H. Mizuseki, and Y. Kawazoe, Jpn. J. Appl. Phys., 44, 2823 (2005). [3] R. V. Belosludov, A. A. Farajian, H. Mizuseki, K. Miki, and Y. Kawazoe, Phys. Rev. B, 75, 113411 (2007). [4] S.-U. Lee, R. V. Belosludov, H. Mizuseki, and Y. Kawazoe, Small 4 (2008) 962. [5] S.-U Lee, R. V. Belosludov, H. Mizuseki, and Y. Kawazoe, J. Phys. Chem. C. 111 (2007) 15397.

  6. Compositional and functional dynamics of dried papaya as affected by storage time and packaging material.

    PubMed

    Udomkun, Patchimaporn; Nagle, Marcus; Argyropoulos, Dimitrios; Mahayothee, Busarakorn; Latif, Sajid; Müller, Joachim

    2016-04-01

    Papaya has been identified as a valuable source of nutrients and antioxidants, which are beneficial for human health. To preserve the nutritional properties after drying, appropriate storage specifications should be considered. This study aimed to investigate the quality and stability of air-dried papaya in terms of quality dynamics and behavior of bio-active compounds during storage for up to 9 months in two packaging materials: aluminum laminated polyethylene and polyamide/polyethylene. Samples with moisture content (MC) of 0.1328 g g(-1) and water activity (aw) of 0.5 were stored at 30 °C and relative humidity (RH) of 40-50%. The MC, aw, degree of browning (DB) and 5-hydroxymethylfurfural (HMF) content were found to notably increase as storage progressed. On the contrary, there was a significant decrease in antioxidant capacity (DPPH, FRAP and ABTS), total phenolic (TP) and ascorbic acid (AA) contents. Packaging in aluminum laminated polyethylene under ambient conditions was found to better preserve bio-active compounds and retard increases in MC, aw and DB, when compared to polyamide/polyethylene. PMID:26593545

  7. Quantitative Computed Tomography Protocols Affect Material Mapping and Quantitative Computed Tomography-Based Finite-Element Analysis Predicted Stiffness.

    PubMed

    Giambini, Hugo; Dragomir-Daescu, Dan; Nassr, Ahmad; Yaszemski, Michael J; Zhao, Chunfeng

    2016-09-01

    Quantitative computed tomography-based finite-element analysis (QCT/FEA) has become increasingly popular in an attempt to understand and possibly reduce vertebral fracture risk. It is known that scanning acquisition settings affect Hounsfield units (HU) of the CT voxels. Material properties assignments in QCT/FEA, relating HU to Young's modulus, are performed by applying empirical equations. The purpose of this study was to evaluate the effect of QCT scanning protocols on predicted stiffness values from finite-element models. One fresh frozen cadaveric torso and a QCT calibration phantom were scanned six times varying voltage and current and reconstructed to obtain a total of 12 sets of images. Five vertebrae from the torso were experimentally tested to obtain stiffness values. QCT/FEA models of the five vertebrae were developed for the 12 image data resulting in a total of 60 models. Predicted stiffness was compared to the experimental values. The highest percent difference in stiffness was approximately 480% (80 kVp, 110 mAs, U70), while the lowest outcome was ∼1% (80 kVp, 110 mAs, U30). There was a clear distinction between reconstruction kernels in predicted outcomes, whereas voltage did not present a clear influence on results. The potential of QCT/FEA as an improvement to conventional fracture risk prediction tools is well established. However, it is important to establish research protocols that can lead to results that can be translated to the clinical setting. PMID:27428281

  8. Correlation Between Domain Behavior and Magnetic Properties of Materials

    SciTech Connect

    Jeffrey Scott Leib

    2003-05-31

    Correlation between length scales in the field of magnetism has long been a topic of intensive study. The long-term desire is simple: to determine one theory that completely describes the magnetic behavior of matter from an individual atomic particle all the way up to large masses of material. One key piece to this puzzle is connecting the behavior of a material's domains on the nanometer scale with the magnetic properties of an entire large sample or device on the centimeter scale. In the first case study involving the FeSiAl thin films, contrast and spacing of domain patterns are clearly related to microstructure and stress. Case study 2 most clearly demonstrates localized, incoherent domain wall motion switching with field applied along an easy axis for a square hysteresis loop. In case study 3, axis-specific images of the complex Gd-Si-Ge material clearly show the influence of uniaxial anisotropy. Case study 4, the only study with the sole intent of creating domain structures for imaging, also demonstrated in fairly simple terms the effects of increasing stress on domain patterns. In case study 5, it was proven that the width of magnetoresistance loops could be quantitatively predicted using only MFM. When all of the case studies are considered together, a dominating factor seems to be that of anisotropy, both magneticrostaylline and stress induced. Any quantitative bulk measurements heavily reliant on K coefficients, such as the saturation fields for the FeSiAl films, H{sub c} in cases 1, 3, and 5, and the uniaxial character of the Gd{sub 5}(Si{sub 2}Ge{sub 2}), transferred to and from the domain scale quite well. In-situ measurements of domain rotation and switching, could also be strongly correlated with bulk magnetic properties, including coercivity, M{sub s}, and hysteresis loop shape. In most cases, the qualitative nature of the domain structures, when properly considered, matched quite well to what might have been expected from theory and calculation

  9. Structure-property relationships of multiferroic materials: A nano perspective

    NASA Astrophysics Data System (ADS)

    Bai, Feiming

    The integration of sensors, actuators, and control systems is an ongoing process in a wide range of applications covering automotive, medical, military, and consumer electronic markets. Four major families of ceramic and metallic actuators are under development: piezoelectrics, electrostrictors, magnetostrictors, and shape-memory alloys. All of these materials undergo at least two phase transformations with coupled thermodynamic order parameters. These transformations lead to complex domain wall behaviors, which are driven by electric fields (ferroelectrics), magnetic fields (ferromagnetics), or mechanical stress (ferroelastics) as they transform from nonferroic to ferroic states, contributing to the sensing and actuating capabilities. This research focuses on two multiferroic crystals, Pb(Mg1/3Nb 2/3)O3-PbTiO3 and Fe-Ga, which are characterized by the co-existence and coupling of ferroelectric polarization and ferroelastic strain, or ferro-magnetization and ferroelastic strain. These materials break the conventional boundary between piezoelectric and electrostrictors, or magnetostrictors and shape-memory alloys. Upon applying field or in a poled condition, they yield not only a large strain but also a large strain over field ratio, which is desired and much benefits for advanced actuator and sensor applications. In this thesis, particular attention has been given to understand the structure-property relationships of these two types of materials from atomic to the nano/macro scale. X-ray and neutron diffraction were used to obtain the lattice structure and phase transformation characteristics. Piezoresponse and magnetic force microscopy were performed to establish the dependence of domain configurations on composition, thermal history and applied fields. It has been found that polar nano regions (PNRs) make significant contributions to the enhanced electromechanical properties of PMN-x%PT crystals via assisting intermediate phase transformation. With increasing PT

  10. Deacetylation affects the physical properties and bioactivity of acemannan, an extracted polysaccharide from Aloe vera.

    PubMed

    Chokboribal, Jaroenporn; Tachaboonyakiat, Wanpen; Sangvanich, Polkit; Ruangpornvisuti, Vithaya; Jettanacheawchankit, Suwimon; Thunyakitpisal, Pasutha

    2015-11-20

    Acemannan, an acetylated polymannose from Aloe vera, induces tissue repair. We investigated the role of acemannan's acetyl-groups on its physical and biological properties. Deacetylated acemannan (DeAcAM) was prepared and characterized. The physical properties and microscopic structure of DeAcAM were evaluated using water solubility, contact angle, X-ray diffraction, and scanning-electron microscopy. The activity of DeAcAM on cell proliferation and gene expression were assessed. Acemannan and DeAcAM structures were simulated and the acemannan tetramer diad and its completely deacetylated structure were also determined. Increased acemannan deacetylation reduced its water solubility and hydrophilicity. Complete deacetylation altered acemannan's conformation to a partial crystal structure. The bioactivity of acemannan was reduced corresponding to its deacetylation. Acemannan induced cell proliferation, and VEGF and Collagen I expression; however, 100% DeAcAM did not. The simulated structures of the acemannan diad and the completely deacetylated diad were different. We conclude acetyl-groups affect acemannan's structure and physical/biological properties. PMID:26344314

  11. Hydration kinetics and physical properties of split chickpea as affected by soaking temperature and time.

    PubMed

    Johnny, Saeed; Razavi, Seyed M A; Khodaei, Diako

    2015-12-01

    In this study, some physical properties (principal dimensions, mean diameters, sphericity, area, density and electrical conductivity) of split chickpea were measured as function of soaking time (up to 360 min) and temperature (25-65 °C). Initially, the water absorption rate was high and then it showed a progressive decrease at all temperatures, whereas solid loss exhibited a power function of temperature (P < 0.05). The Peleg model was predicted well the kinetic of split chickpea soaking. No significant difference (P < 0.05) was observed in Peleg rate constant (K1) and Peleg capacity constant (K2) at all temperatures except for K1 at 25 °C. The discrepancy for K1 was in relation to permeability characteristics of split chickpea at temperature of 25 °C. As temperature increased from 25 to 65 °C, the K1 value decreased from 0.04620 to 0.00945 g h(-1), whereas the K2 value increased from 0.08597 to 0.11320 g(-1). Plot for K1 exhibited a slope changes around 45 °C corresponding to gelatinization temperature of split chickpeas. The effect of temperature and time on physical properties of split chickpea during soaking was monitored by regression equations. It was concluded that physical properties of split chickpea affected by its water absorption especially at higher temperatures. PMID:26604418

  12. Dynamic material properties of refractory materials: Tantalum and tantalum/tungsten alloys

    SciTech Connect

    Furnish, M.D.; Chhabildas, L.C.; Lassila, D.H.; Steinberg, D.J.

    1995-08-01

    We have made a careful set of impact wave-profile measurements (16 profiles) on tantalum and tantalum-tungsten alloys at relatively low stresses (to 15 GPa). Alloys used were Ta{sub 97.5}W{sub 2.5} and Ta{sub 90}W{sub 10} (wt. %) with oxygen contents of 30--70 ppM. Information available from these experiments includes Hugoniot, elastic limits, loading fates, spall strength, unloading paths, reshock structure and specimen thickness effects. Hugoniot and spall properties are illustrated, and are consistent with expectations from earlier work. Modeling the tests with the Steinberg-Lund rate-dependent material model provides for an excellent match of the shape of the plastic wave, although the release wave is not well modeled. There is also a discrepancy between experiments and calculations regarding the relative timing of the elastic and plastic waves that may be due to texture effects.

  13. Frequency Response of Synthetic Vocal Fold Models with Linear and Nonlinear Material Properties

    ERIC Educational Resources Information Center

    Shaw, Stephanie M.; Thomson, Scott L.; Dromey, Christopher; Smith, Simeon

    2012-01-01

    Purpose: The purpose of this study was to create synthetic vocal fold models with nonlinear stress-strain properties and to investigate the effect of linear versus nonlinear material properties on fundamental frequency (F[subscript 0]) during anterior-posterior stretching. Method: Three materially linear and 3 materially nonlinear models were…

  14. Synthesis and properties of the materials obtained by SHS mode for radiation protection

    NASA Astrophysics Data System (ADS)

    Isachenko, D. S.; Dolmatov, O. Yu; Semenov, A. O.; Chursin, S. S.; Kuznetsov, M. S.

    2016-06-01

    The article shows the process of protective composite materials manufacturing. Also, the analysis of experimental results concerning the composite materials protective properties is given. The advantages of SHS method are considered in comparison with traditional materials. The uniqueness of SHS obtained products based on combination of nuclear-physical properties and parameters is presented.

  15. Factors Influencing the Dielectric Properties of Agricultural Products and Food Materials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dielectric properties of materials are defined, and the major factors that influence these properties of agricultural and food materials, namely, frequency of the applied radio-frequency and microwave electric fields, water content, temperature, and density of the materials are discussed on the bas...

  16. Comparative Evaluation of Physical Properties of Four Tissue Conditioners Relined to Modeling Plastic Material

    PubMed Central

    Monzavi, Abbas; Siadat, Hakimeh; Atai, Mohammad; Alikhasi, Marzieh; Nazari, Vahideh; Sheikhzadeh, Sadigheh

    2013-01-01

    Objective: Little is known about the interaction of tissue conditioners and modeling plastics. This study evaluates the influence of a variety of commercial tissue conditioners on alteration of viscoelastic properties of modeling plastics. Materials and Methods: In this in vitro study, the dynamic viscoelastic properties of four commercially available tissue conditioners (TC), Visco-gel (VG), GC Soft-Liner (SL), FITT (FT), and Coe Comfort (CC), relined to modeling plastics with a thickness of 2mm were evaluated after 1 and 7 days of water immersion with the use of storage modulus, loss modulus, and tan delta parameters. Values for these three parameters for each tissue conditioner were statistically analyzed by Kruskal Wallis and Mann Whitney tests with P value sets at<0.05. Results: Complex modulus and loss tangent values of TC were not significantly different among specimens containing 0, 2, 5 and 10 wt.%-SZ, respectively. In FT and TC containing 2 wt.%-SZ, these values were not significantly different between 1 and 28 days in both water- and saliva immersions. Conclusion: The results suggest that relining with modeling plastics does affect TC’s inherent dynamic viscoelastic properties, while the other tissue conditioners investigated may be found to have changed viscoelastic properties as a consequence of vicinity to the modeling plastics. PMID:24910661

  17. Tuning a material's properties through the excitation of localized defect modes

    NASA Astrophysics Data System (ADS)

    Serra Garcia, Marc; Lydon, Joseph; Daraio, Chiara

    2015-03-01

    Technological applications such as acoustic super-lenses and vibration mitigation devices require materials with extreme mechanical properties (Very high, zero, or negative stiffness). These properties can be achieved through buckling instabilities, local resonances and phase transitions, mechanisms that are limited to particular frequencies, strains or temperatures. In this talk I will present an alternative mechanism to tune the stiffness of a lattice. The mechanism is based on the excitation of a nonlinear localized defect mode. The oscillation of the defect mode affects the bulk properties of the lattice. This is due to the thermal expansion of the defect mode and the nonlinear coupling between the mode amplitude and the strain of the lattice. Due to the singular properties of nonlinear systems near bifurcation points, the lattice can achieve an arbitrarily large stiffness. It is possible to select point of the force-displacement relation that is being tuned by selecting the defect's excitation frequency and amplitude. Depending on the nonlinear interaction potential at the defect site, the stiffness can be tuned to extremely positive or extremely negative values. While our theoretical and experimental results have been obtained in a granular crystal, the analysis suggests that an equivalent effect should be present in other lattices with localized modes and nonlinearity.

  18. Effects of material property and heat treatment on nanomechanical properties of chitosan films.

    PubMed

    Majd, Shervin; Yuan, Youling; Mishra, Sanjay; Haggard, Warren O; Bumgardner, Joel D

    2009-07-01

    The influence of degree of deacetylation (DDA), molecular weight (MW), and heat treatment on nanomechanical properties of three different chitosan coatings was assessed. Chitosans (2.5 wt % in 2% acetic acid) were solution cast and bonded to glass slides, subjected to 40, 70, or 90 degrees C heat treatments for 1 h, and then allowed to air dry. Non-heat treated films were used as controls. The nanomechanical and structural properties were evaluated using quasi-static nanoindentation, X-ray diffraction (XRD), and atomic force microscopy (AFM). Nanoindentation results showed that the coating with the lowest MW and highest DDA (95.6% DDA and MW = 2.43 x 10(6) Da) had higher reduced modulus of elasticity, (E = 4.02 +/- 0.85 GPa) as compared to the other chitosans; 76.1% DDA/MW = 3.20 x 10(6) Da, E = 3.66 +/- 0.68 GPa, and 92.3% DDA/MW = 7.52 x 10(6) Da, E = 3.56 +/- 0.25 GPa; (n = 75, p < 0.05). Crystallinity index, estimated via XRD, ranged from 36.4% +/- 1% to 49.7% +/- 6.5%. AFM revealed the presence of different crystalline morphologies such as needle-like crystals, sheet-like crystals, and small spherulites. The heat treatments applied during solution casting of the chitosan coatings did not affect morphology or nanomechanical properties. In conclusion, nanomechanical properties of chitosan coatings varied with DDA and MW and may be important to cell/tissue interactions. PMID:19072977

  19. Electronic Properties of Low-Dimensional Materials Under Periodic Potential

    NASA Astrophysics Data System (ADS)

    Jamei, Mehdi

    In the quest for the further miniaturization of electronic devices, numerous fabrication techniques have been developed. The semiconductor industry has been able to manifest miniaturization in highly complex and ultra low-power integrated circuits and devices, transforming almost every aspect of our lives. However, we may have come very close to the end of this trend. While advanced machines and techniques may be able to overcome technological barriers, theoretical and fundamental barriers are inherent to the top-down miniaturization approach and cannot be circumvented. As a result, the need for novel and natural alternatives to replace old materials is valued now more than ever. Fortunately, there exists a large group of materials that essentially has low-dimensional (quasi-one- or quasi-two-dimensional) structures. Graphene, a two-dimensional form of carbon, which has attracted a lot of attention in recent years, is a perfect example of a prime material from this group. Niobium tri-selenide (NbSe3), from a family of trichalcogenides, has a highly anisotropic structure and electrical conductivity. At sufficiently low temperatures, NbSe3 also exhibits two independent "sliding charge density waves"-- an exciting phenomenon, which could be altered by changing the overall size of the material. In NbSe3 (and Blue Bronze K0.3MoO3 which has a similar structure and electrical behavior), the effect of a periodic potential could be seen in creating a charge density wave (CDW) that is incommensurate to the underlying lattice. The required periodic potential is provided by the crystal ions when ordered in a particular way. The consequence is a peculiar non-linear conductivity behavior, as well as a unique narrow-band noise spectrum. Theoretical and experimental studies have concluded that the dynamic properties of resulting CDW are directly related to the crystal impurity density, and other pinning potentials. Therefore, reducing the overall size of the crystal could

  20. Understanding and Predicting the Thermal Explosion Violence of HMX-Based and RDX-Based Explosives - Experimental Measurements of Material Properties and Reaction Violence

    SciTech Connect

    Maienschein, J L; Wardell, J F; Weese, R K; Cunningham, B J; Tran, T D

    2002-07-03

    The violence of thermal explosions with energetic materials is affected by many material properties, including mechanical and thermal properties, thermal ignition kinetics, and deflagration behavior. These properties must be characterized for heated samples as well as pristine materials. We present available data for these properties for two HMX-based formulations--LX-04 and PBX-9501, and two RDX-based formulations--Composition B and PBXN-109. We draw upon separately published data on the thermal explosion violence with these materials to compare the material properties with the observed violence. We have the most extensive data on deflagration behavior of these four formulations, and we discuss the correlation of the deflagration data with the violence results. The data reported here may also be used to develop models for application in simulation codes such as ALE3D to calculate and Dredict thermal explosion violence.