Effect of storage time on the viscoelastic properties of elastomeric impression materials.

PubMed

Papadogiannis, Dimitris; Lakes, Roderic; Palaghias, George; Papadogiannis, Yiannis

2012-01-01

The aim of this study was to evaluate creep and viscoelastic properties of dental impression materials after different storage times. Six commercially available impression materials (one polyether and five silicones) were tested after being stored for 30 min to 2 weeks under both static and dynamic testing. Shear and Young's moduli, dynamic viscosity, loss tangent and other viscoelastic parameters were calculated. Four of the materials were tested 1 h after setting under creep for three hours and recovery was recorder for 50 h. The tested materials showed differences among them, while storage time had significant influence on their properties. Young's modulus E ranged from 1.81 to 12.99 MPa with the polyether material being the stiffest. All of the materials showed linear viscoelastic behavior exhibiting permanent deformation after 50h of creep recovery. As storage time affects the materials' properties, pouring time should be limited in the first 48 h after impression. Copyright © 2011 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

Impact Testing of Aluminum 2024 and Titanium 6Al-4V for Material Model Development

NASA Technical Reports Server (NTRS)

Pereira, J. Michael; Revilock, Duane M.; Lerch, Bradley A.; Ruggeri, Charles R.

2013-01-01

One of the difficulties with developing and verifying accurate impact models is that parameters such as high strain rate material properties, failure modes, static properties, and impact test measurements are often obtained from a variety of different sources using different materials, with little control over consistency among the different sources. In addition there is often a lack of quantitative measurements in impact tests to which the models can be compared. To alleviate some of these problems, a project is underway to develop a consistent set of material property, impact test data and failure analysis for a variety of aircraft materials that can be used to develop improved impact failure and deformation models. This project is jointly funded by the NASA Glenn Research Center and the FAA William J. Hughes Technical Center. Unique features of this set of data are that all material property data and impact test data are obtained using identical material, the test methods and procedures are extensively documented and all of the raw data is available. Four parallel efforts are currently underway: Measurement of material deformation and failure response over a wide range of strain rates and temperatures and failure analysis of material property specimens and impact test articles conducted by The Ohio State University; development of improved numerical modeling techniques for deformation and failure conducted by The George Washington University; impact testing of flat panels and substructures conducted by NASA Glenn Research Center. This report describes impact testing which has been done on aluminum (Al) 2024 and titanium (Ti) 6Al-4vanadium (V) sheet and plate samples of different thicknesses and with different types of projectiles, one a regular cylinder and one with a more complex geometry incorporating features representative of a jet engine fan blade. Data from this testing will be used in validating material models developed under this program. The material tests and the material models developed in this program will be published in separate reports.

NREL Researchers Create New Materials With Unusual Properties | News | NREL

Science.gov Websites

show how such new low-density materials can be made - with unique properties remarkably different from compounds with atomic structures that didn't match, the researchers theorized that mixing two different high manganese telluride (MnTe) that have different crystal structures - the approach known as heterostructural

Functionalized mesoporous materials for adsorption and release of different drug molecules: A comparative study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang Gang; Otuonye, Amy N.; Blair, Elizabeth A.

2009-07-15

The adsorption capacity and release properties of mesoporous materials for drug molecules can be improved by functionalizing their surfaces with judiciously chosen organic groups. Functionalized ordered mesoporous materials containing various types of organic groups via a co-condensation synthetic method from 15% organosilane and by post-grafting organosilanes onto a pre-made mesoporous silica were synthesized. Comparative studies of their adsorption and release properties for various model drug molecules were then conducted. Functional groups including 3-aminopropyl, 3-mercaptopropyl, vinyl, and secondary amine groups were used to functionalize the mesoporous materials while rhodamine 6G and ibuprofen were utilized to investigate the materials' relative adsorption andmore » release properties. The self-assembly of the mesoporous materials was carried out in the presence of cetyltrimethylammonium bromide (CTAB) surfactant, which produced MCM-41 type materials with pore diameters of {approx}2.7-3.3 nm and moderate to high surface areas up to {approx}1000 m{sup 2}/g. The different functional groups introduced into the materials dictated their adsorption capacity and release properties. While mercaptopropyl and vinyl functionalized samples showed high adsorption capacity for rhodamine 6G, amine functionalized samples exhibited higher adsorption capacity for ibuprofen. While the diffusional release of ibuprofen was fitted on the Fickian diffusion model, the release of rhodamine 6G followed Super Case-II transport model. - Graphical abstract: The adsorption capacity and release properties of mesoporous materials for various drug molecules are tuned by functionalizing the surfaces of the materials with judiciously chosen organic groups. This work reports comparative studies of the adsorption and release properties of functionalized ordered mesoporous materials containing different hydrophobic and hydrophilic groups that are synthesized via a co-condensation and post-grafting methods for various model drug molecules.« less

Differences in Tribological Behaviors upon Switching Fixed and Moving Materials of Tribo-pairs including Metal and Polymer.

PubMed

Xu, Aijie; Tian, Pengyi; Wen, Shizhu; Guo, Fei; Hu, Yueqiang; Jia, Wenpeng; Dong, Conglin; Tian, Yu

2017-10-12

The coefficient of friction (COF) between two materials is usually believed to be an intrinsic property of the materials themselves. In this study, metals of stainless steel (304) and brass (H62), and polymers of polypropylene (PP) and polytetrafluoroethylene (PTFE) were tested on a standard ball-on-three-plates test machine. Significantly different tribological behaviors were observed when fixed and moving materials of tribo-pairs (metal/polymer) were switched. As an example, under the same applied load and rotating speed, the COF (0.49) between a rotating PP ball and three fixed H62 plates was approximately 2.3 times higher than that between switched materials of tribo-pairs. Meanwhile, the COF between H62 and PTFE was relatively stable. The unexpected tribological behaviors were ascribed to the thermal and mechanical properties of tribo-pairs. Theoretical analysis revealed that the differences in the maximum local temperature between switching the fixed and moving materials of tribo-pairs were consistent with the differences in the tested COF. This result indicated the precise prediction of the COF of two materials is complexcity, and that thermal and mechanical properties should be properly considered in designing tribo-pairs, because these properties may significantly affect tribological performance.

Emission properties of Ce3+ centers in barium borate glasses prepared from different precursor materials

NASA Astrophysics Data System (ADS)

Torimoto, Aya; Masai, Hirokazu; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki; Ohkubo, Takahiro

2017-10-01

The photoluminescence (PL) and X-ray induced luminescence properties of Ce-doped barium borate glasses prepared from different precursor materials have been investigated. Oxidation of Ce3+ takes place during the melting process performed using a pre-vitrified non-doped glass. Residual groups originated from the precursor materials, such as fluorine atoms and OH groups, are found to affect the optical and emission properties of the glasses. Moreover, both the PL and the X-ray induced luminescence properties of the glasses depend on the precursor materials used for their synthesis. Based on a thorough analysis of the emission properties, we conclude that the best synthesis conditions involve melting a batch containing Ce(CH3COO)3·H2O, BaCO3, and B2O3 in Ar atmosphere.

Validation and refinement of mixture volumetric material properties identified in superpave monitoring project II : phase II.

DOT National Transportation Integrated Search

2015-02-01

This study was initiated to validate and refine mixture volumetric material properties identified in the : Superpave Monitoring Project II. It has been found that differences in performance are primarily controlled : by differences in gradation and r...

Outdoor weathering of facial prosthetic elastomers differing in Durometer hardness.

PubMed

Willett, Emily S; Beatty, Mark W

2015-03-01

Facial prosthetic elastomers with wide ranges in hardness are available, yet material weatherability is unknown. The purpose of this study was to assess color, Durometer hardness, and tensile property changes after 3000 hours of outdoor weathering. Unpigmented elastomers with Durometer hardness 5, 30, 50, 70, and A-2186 were polymerized into dumbbells (ASTM D412) and disks, 34 mm in diameter by 6 mm thick. Materials were subjected to outdoor or time passage environments for 3000 hours. CIELab color (n=5), Durometer hardness (n=5), and tensile mechanical properties (n=10) were measured at 0 and 3000 hours, and group differences were assessed by material and weathering condition (ANOVA/Tukey, α=.05). Except for A-2186, the mean Durometer changes for all materials were 1 unit or less, with no significant differences observed between time passage and weathered groups (P≥.05). Three-thousand-hour tensile mechanical property results demonstrated nonsignificant differences between time passage and weathered materials but significantly changed properties from immediately tested materials (P<.001). Outdoor weathering induced perceptible but acceptable color changes (1.7≤ΔE*≤2.6) for elastomers with Durometer hardness 5 and 30 and A-2186. With a few exceptions, outdoor weathering produced relatively small changes in color, Durometer hardness, or tensile properties compared with time passage. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Structure and physical properties of silkworm cocoons

PubMed Central

Chen, Fujia; Porter, David; Vollrath, Fritz

2012-01-01

Silkworm cocoons have evolved a wide range of different structures and combinations of physical and chemical properties in order to cope with different threats and environmental conditions. We present our observations and measurements on 25 diverse types of cocoons in a first attempt to correlate physical properties with the structure and morphology of the cocoons. These two architectural parameters appear to be far more important than the material properties of the silk fibres themselves. We consider tensile and compressive mechanical properties and gas permeation of the cocoon walls, and in each case identify mechanisms or models that relate these properties to cocoon structure, usually based upon non-woven fibre composites. These properties are of relevance also for synthetic non-woven composite materials and our studies will help formulate bio-inspired design principles for new materials. PMID:22552916

David Adler Lectureship Award: n-point Correlation Functions in Heterogeneous Materials.

NASA Astrophysics Data System (ADS)

Torquato, Salvatore

2009-03-01

The determination of the bulk transport, electromagnetic, mechanical, and optical properties of heterogeneous materials has a long and venerable history, attracting the attention of some of the luminaries of science, including Maxwell, Lord Rayleigh, and Einstein. The bulk properties can be shown to depend rigorously upon infinite sets of various n-point correlation functions. Many different types of correlation functions arise, depending on the physics of the problem. A unified approach to characterize the microstructure and bulk properties of a large class of disordered materials is developed [S. Torquato, Random Heterogeneous Materials: Microstructure and Macroscopic Properties (Springer-Verlag, New York, 2002)]. This is accomplished via a canonical n-point function Hn from which one can derive exact analytical expressions for any microstructural function of interest. This microstructural information can then be used to estimate accurately the bulk properties of the material. Unlike homogeneous materials, seemingly different bulk properties (e.g., transport and mechanical properties) of a heterogeneous material can be linked to one another because of the common microstructure that they share. Such cross-property relations can be used to estimate one property given a measurement of another. A recently identified decorrelation principle, roughly speaking, refers to the phenomenon that unconstrained correlations that exist in low-dimensional disordered materials vanish as the space dimension becomes large. Among other results, this implies that in sufficiently high dimensions the densest spheres packings may be disordered (rather than ordered) [S. Torquato and F. H. Stillinger, ``New Conjectural Lower Bounds on the Optimal Density of Sphere Packings," Experimental Mathematics, 15, 307 (2006)].

Adjustment of Part Properties for an Elastomeric Laser Sintering Material

NASA Astrophysics Data System (ADS)

Wegner, A.; Ünlü, T.

2018-03-01

Laser sintering of polymers is gaining more and more importance within the field of small series productions. Polyamide 12 is predominantly used, although a variety of other materials are also available for the laser sintering process. For example, elastomeric, rubberlike materials offer very different part property profiles. Those make the production of flexible parts like, e.g., sealings, flexible tubes or shoe soles possible because they offer high part ductility and low hardness. At the chair for manufacturing technology, a new elastomeric laser sintering material has been developed and then commercialized by a spin-off from university. The aim of the presented study was the analysis of the new material's properties. Proof was found that Shore hardness can be modified by varying the parameter settings. Therefore, the correlation between process parameters, energy input, Shore hardness and other part properties like mechanical properties were analyzed. Based on these results, suitable parameter settings were established which lead to the possibility of producing parts with different Shore hardnesses.

Fluorescence of aqueous solutions of commercial humic products

NASA Astrophysics Data System (ADS)

Gosteva, O. Yu.; Izosimov, A. A.; Patsaeva, S. V.; Yuzhakov, V. I.; Yakimenko, O. S.

2012-01-01

We have studied the spectral luminescence characteristics of aqueous solutions of humic products obtained from different raw material sources, and their behavior as the excitation wavelength increases from 270 nm to 355 nm. We have identified differences in the spectral properties of industrial humic products from coalified materials, lignin-containing organic waste, and humic products from plant raw material (peat, sapropel, vermicompost). We have shown that humic products from plant raw material have spectral properties closer to those for humic substances in natural water or soil than humic products from coalified materials.

Data analytics and parallel-coordinate materials property charts

NASA Astrophysics Data System (ADS)

Rickman, Jeffrey M.

2018-01-01

It is often advantageous to display material properties relationships in the form of charts that highlight important correlations and thereby enhance our understanding of materials behavior and facilitate materials selection. Unfortunately, in many cases, these correlations are highly multidimensional in nature, and one typically employs low-dimensional cross-sections of the property space to convey some aspects of these relationships. To overcome some of these difficulties, in this work we employ methods of data analytics in conjunction with a visualization strategy, known as parallel coordinates, to represent better multidimensional materials data and to extract useful relationships among properties. We illustrate the utility of this approach by the construction and systematic analysis of multidimensional materials properties charts for metallic and ceramic systems. These charts simplify the description of high-dimensional geometry, enable dimensional reduction and the identification of significant property correlations and underline distinctions among different materials classes.

The Process of Nanostructuring of Metal (Iron) Matrix in Composite Materials for Directional Control of the Mechanical Properties

PubMed Central

Zemtsova, Elena

2014-01-01

We justified theoretical and experimental bases of synthesis of new class of highly nanostructured composite nanomaterials based on metal matrix with titanium carbide nanowires as dispersed phase. A new combined method for obtaining of metal iron-based composite materials comprising the powder metallurgy processes and the surface design of the dispersed phase is considered. The following stages of material synthesis are investigated: (1) preparation of porous metal matrix; (2) surface structuring of the porous metal matrix by TiC nanowires; (3) pressing and sintering to give solid metal composite nanostructured materials based on iron with TiC nanostructures with size 1–50 nm. This material can be represented as the material type “frame in the frame” that represents iron metal frame reinforcing the frame of different chemical compositions based on TiC. Study of material functional properties showed that the mechanical properties of composite materials based on iron with TiC dispersed phase despite the presence of residual porosity are comparable to the properties of the best grades of steel containing expensive dopants and obtained by molding. This will solve the problem of developing a new generation of nanostructured metal (iron-based) materials with improved mechanical properties for the different areas of technology. PMID:24695459

The process of nanostructuring of metal (iron) matrix in composite materials for directional control of the mechanical properties.

PubMed

Zemtsova, Elena; Yurchuk, Denis; Smirnov, Vladimir

2014-01-01

We justified theoretical and experimental bases of synthesis of new class of highly nanostructured composite nanomaterials based on metal matrix with titanium carbide nanowires as dispersed phase. A new combined method for obtaining of metal iron-based composite materials comprising the powder metallurgy processes and the surface design of the dispersed phase is considered. The following stages of material synthesis are investigated: (1) preparation of porous metal matrix; (2) surface structuring of the porous metal matrix by TiC nanowires; (3) pressing and sintering to give solid metal composite nanostructured materials based on iron with TiC nanostructures with size 1-50 nm. This material can be represented as the material type "frame in the frame" that represents iron metal frame reinforcing the frame of different chemical compositions based on TiC. Study of material functional properties showed that the mechanical properties of composite materials based on iron with TiC dispersed phase despite the presence of residual porosity are comparable to the properties of the best grades of steel containing expensive dopants and obtained by molding. This will solve the problem of developing a new generation of nanostructured metal (iron-based) materials with improved mechanical properties for the different areas of technology.

Thermal properties of alkali-activated aluminosilicates with CNT admixture

NASA Astrophysics Data System (ADS)

Zmeskal, Oldrich; Trhlikova, Lucie; Fiala, Lukas; Florian, Pavel; Cerny, Robert

2017-07-01

Material properties of electrically conductive cement-based materials with increased attention paid on electric and thermal properties were often studied in the last years. Both electric and thermal properties play an important role thanks to their possible utilization in various practical applications (e.g. snow-melting systems or building structures monitoring systems without the need of an external monitoring system). The DC/AC characteristics depend significantly on the electrical resistivity and the electrical capacity of bulk materials. With respect to the DC/AC characteristics of cement-based materials, such materials can be basically classified as electric insulators. In order to enhance them, various conductive admixtures such as those based on different forms of carbon, can be used. Typical representatives of carbon-based admixtures are carbon nanotubes (CNT), carbon fibers (CF), graphite powder (GP) and carbon black (CB). With an adequate amount of such admixtures, electric properties significantly change and new materials with higher added value can be prepared. However, other types of materials can be enhanced in the same way. Alkali-activated aluminosilicates (AAA) based on blast furnace slag are materials with high compressive strength comparable with cement-based materials. Moreover, the price of slag is lower than of Portland cement. Therefore, this paper deals with the study of thermal properties of this promising material with different concentrations of CNT. Within the paper a simple method of basic thermal parameters determination based on the thermal transient response to a heat power step is presented.

Effect of size on bulk and surface cohesion energy of metallic nano-particles

NASA Astrophysics Data System (ADS)

Yaghmaee, M. S.; Shokri, B.

2007-04-01

The knowledge of nano-material properties not only helps us to understand the extreme behaviour of small-scale materials better (expected to be different from what we observe from their bulk value) but also helps us to analyse and design new advanced functionalized materials through different nano technologies. Among these fundamental properties, the cohesion (binding) energy mainly describes most behaviours of materials in different environments. In this work, we discuss this fundamental property through a nano-thermodynamical approach using two algorithms, where in the first approach the size dependence of the inner (bulk) cohesion energy is studied, and in the second approach the surface cohesion energy is considered too. The results, which are presented through a computational demonstration (for four different metals: Al, Ga, W and Ag), can be compared with some experimental values for W metallic nano-particles.

Silicon-containing polymer-derived ceramic nanocomposites (PDC-NCs): preparative approaches and properties.

PubMed

Ionescu, Emanuel; Kleebe, Hans-Joachim; Riedel, Ralf

2012-08-07

Composites consist by definition of at least two materials (Gibbsian phases) with rather different properties. They exhibit a heterogeneous microstructure and possess improved properties with respect to their components. Furthermore, the design of their microstructure allows for tailoring their overall properties. In the last decades, intense work was performed on the synthesis of nanocomposites, which have the feature that at least one of their components is nanoscaled. However, the microstructure-property relationship of nanocomposite materials is still a challenging topic. This tutorial review paper deals with a special class of nanocomposites, i.e. polymer-derived ceramic nanocomposites (PDC-NCs), which have been shown to be promising materials for various structural and functional applications. Within this context, different preparative approaches for PDC-NCs as well as some of their properties will be presented and discussed. Furthermore, recent results concerning the relationship between the nano/microstructure of PDC-NCs and their properties will be highlighted.

Cure Schedule for Stycast 2651/Catalyst 11.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kropka, Jamie Michael; McCoy, John D.

2017-11-01

The Henkel technical data sheet (TDS) for Stycast 2651/Catalyst 11 lists three alternate cure schedules for the material, each of which would result in a different state of reaction and different material properties. Here, a cure schedule that attains full reaction of the material is defined. The use of this cure schedule will eliminate variance in material properties due to changes in the cure state of the material, and the cure schedule will serve as the method to make material prior to characterizing properties. The following recommendation was motivated by (1) a desire to cure at a single temperature formore » ease of manufacture and (2) a desire to keep the cure temperature low (to minimize residual stress build-up associated with the cooldown from the cure temperature to room temperature) without excessively limiting the cure reaction due to vitrification (i.e., material glass transition temperature, T g, exceeding cure temperature).« less

Material Property Characterization of Potential Nanocarbon Metal-Matrix Composite: An Investigational Study

NASA Astrophysics Data System (ADS)

Zavala, Mitchel

Metal-matrix composites (MMCs) are engineered combinations of two or more materials. Tailored properties are achieved by systematic combinations of different constituents. Specialized design and synthesis procedures allow unique sets of material properties in composites. Covetics are a new type of metal-matrix nano-composite (MMnC) material. These materials are formed from FCC metals which are super-saturated with up to 10 wt. % of activated nano-carbon powder. The idea is that the nano-carbon particles will enhance the material properties of the base metal matrix, however most of the physical and mechanical properties of covetics have not been well characterized. The foci of this study are to optimize the covetic casting synthesis process under controlled conditions, to understand and analyze the microstructures of the synthesized copper and aluminum covetic, to provide a thorough analysis of the chemical composition of the synthesized covetic materials, and to characterize physical and mechanical properties of both of these materials using meticulously prepared samples and test procedures.

A Fundamental Study of Inorganic Clathrate and Other Open-Framework Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nolas, George

Due to formidable synthetic challenges, many materials of scientific and technological interest are first obtained as microcrystalline powders. High purity, high yield processing techniques are often lacking and thus care must be taken in interpretation of the observed structural, chemical, and physical properties of powder or polycrystalline materials, which can be strongly influenced by extrinsic properties. Furthermore, the preparation of high-quality single crystals for many materials by traditional techniques can be especially challenging in cases where the elemental constituents have greatly differing melting points and/or vapor pressures, when the desired compound is thermodynamically metastable, or where growth with participation ofmore » the melt is generally not possible. New processing techniques are therefore imperative in order to investigate the intrinsic properties of these materials and elucidate their fundamental physical properties. Intermetallic clathrates constitute one such class of materials. The complex crystal structures of intermetallic clathrates are characterized by mainly group 14 host frameworks encapsulating guest-ions in polyhedral cages. The unique features of clathrate structures are intimately related to their physical properties, offering ideal systems for the study of structure-property relationships in crystalline solids. Moreover, intermetallic clathrates are being actively investigated due to their potential for application in thermoelectrics, photovoltaics and opto-electronics, superconductivity, and magnetocaloric technologies. We have developed different processing techniques in order to synthesize phase-pure high yield clathrates reproducibly, as well as grow single crystals for the first time. We also employed these techniques to synthesize new “open-framework” compounds. These advances in materials processing and crystal growth allowed for the investigation of the physical properties of a variety of different clathrate compositions for the first time.« less

Photoconductivity in Dirac materials

NASA Astrophysics Data System (ADS)

Shao, J. M.; Yang, G. W.

2015-11-01

Two-dimensional (2D) Dirac materials including graphene and the surface of a three-dimensional (3D) topological insulator, and 3D Dirac materials including 3D Dirac semimetal and Weyl semimetal have attracted great attention due to their linear Dirac nodes and exotic properties. Here, we use the Fermi's golden rule and Boltzmann equation within the relaxation time approximation to study and compare the photoconductivity of Dirac materials under different far- or mid-infrared irradiation. Theoretical results show that the photoconductivity exhibits the anisotropic property under the polarized irradiation, but the anisotropic strength is different between 2D and 3D Dirac materials. The photoconductivity depends strongly on the relaxation time for different scattering mechanism, just like the dark conductivity.

Tendon material properties vary and are interdependent among turkey hindlimb muscles

PubMed Central

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

2012-01-01

SUMMARY 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 (r2=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

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.

Carbon Nanotubes Filled with Ferromagnetic Materials

PubMed Central

Weissker, Uhland; Hampel, Silke; Leonhardt, Albrecht; Büchner, Bernd

2010-01-01

Carbon nanotubes (CNT) filled with ferromagnetic metals like iron, cobalt or nickel are new and very interesting nanostructured materials with a number of unique properties. In this paper we give an overview about different chemical vapor deposition (CVD) methods for their synthesis and discuss the influence of selected growth parameters. In addition we evaluate possible growth mechanisms involved in their formation. Moreover we show their identified structural and magnetic properties. On the basis of these properties we present different application possibilities. Some selected examples reveal the high potential of these materials in the field of medicine and nanotechnology. PMID:28883334

Dynamics of bulk versus nanoscale W S2 : Local strain and charging effects

NASA Astrophysics Data System (ADS)

Luttrell, R. D.; Brown, S.; Cao, J.; Musfeldt, J. L.; Rosentsveig, R.; Tenne, R.

2006-01-01

We measured the infrared vibrational properties of bulk and nanoparticle WS2 in order to investigate the structure-property relations in these materials. In addition to the symmetry-breaking effects of local strain, nanoparticle curvature modifies the local charging environment of the bulk material. Performing a charge analysis on the xy -polarized E1u vibrational mode, we find an approximate 1.5:1 intralayer charge difference between the layered 2H material and inorganic fullerene-like (IF) nanoparticles. This effective charge difference may impact the solid-state lubrication properties of nanoscale metal dichalcogenides.

Dynamics of Bulk vs. Nanoscale WS2: Local Strain and Charging Effects

NASA Astrophysics Data System (ADS)

Musfeldt, J. L.; Brown, S.; Luttrell, R. D.; Cao, J.; Rosentsveig, R.; Tenne, R.

2006-03-01

We measured the infrared vibrational properties of bulk and nanoparticle WS2 in order to investigate the structure- property relations in these novel materials. In addition to the symmetry-breaking effects of local strain, nanoparticle curvature modifies the local charging environment of the bulk material. Performing a charge analysis on the xy-polarized E1u vibrational mode, we find an approximate 1.5:1 intralayer charge difference between the layered 2H material and inorganic fullerene-like (IF) nanoparticles. This effective charge difference may impact the solid-state lubrication properties of nanoscale metal dichalcogenides.

Characterization Report on Fuels for NEAMS Model Validation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gofryk, Krzysztof

Nearly 20% of the world’s electricity today is generated by nuclear energy from uranium dioxide (UO 2) fuel. The thermal conductivity of UO 2 governs the conversion of heat produced from fission events into electricity and it is an important parameter in reactor design and safety. While nuclear fuel operates at high to very high temperatures, thermal conductivity and other materials properties lack sensitivity to temperature variations and to material variations at reactor temperatures. As a result, both the uncertainties in laboratory measurements at high temperatures and the small differences in properties of different materials inevitably lead to large uncertaintiesmore » in models and little predictive power. Conversely, properties measured at low to moderate temperatures have more sensitivity, less uncertainty, and have larger differences in properties for different materials. These variations need to be characterized as they will afford the highest predictive capability in modeling and offer best assurances for validation and verification at all temperatures. This is well emphasized in the temperature variation of the thermal conductivity of UO 2.« less

A review of experimental techniques to produce a nacre-like structure.

PubMed

Corni, I; Harvey, T J; Wharton, J A; Stokes, K R; Walsh, F C; Wood, R J K

2012-09-01

The performance of man-made materials can be improved by exploring new structures inspired by the architecture of biological materials. Natural materials, such as nacre (mother-of-pearl), can have outstanding mechanical properties due to their complicated architecture and hierarchical structure at the nano-, micro- and meso-levels which have evolved over millions of years. This review describes the numerous experimental methods explored to date to produce composites with structures and mechanical properties similar to those of natural nacre. The materials produced have sizes ranging from nanometres to centimetres, processing times varying from a few minutes to several months and a different range of mechanical properties that render them suitable for various applications. For the first time, these techniques have been divided into those producing bulk materials, coatings and free-standing films. This is due to the fact that the material's application strongly depends on its dimensions and different results have been reported by applying the same technique to produce materials with different sizes. The limitations and capabilities of these methodologies have been also described.

Dynamic modulus estimation and structural vibration analysis.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, A.

1998-11-18

Often the dynamic elastic modulus of a material with frequency dependent properties is difficult to estimate. These uncertainties are compounded in any structural vibration analysis using the material properties. Here, different experimental techniques are used to estimate the properties of a particular elastomeric material over a broad frequency range. Once the properties are determined, various structures incorporating the elastomer are analyzed by an interactive finite element method to determine natural frequencies and mode shapes. Then, the finite element results are correlated with results obtained by experimental modal analysis.

Size-Dependent Materials Properties Toward a Universal Equation

PubMed Central

2010-01-01

Due to the lack of experimental values concerning some material properties at the nanoscale, it is interesting to evaluate this theoretically. Through a “top–down” approach, a universal equation is developed here which is particularly helpful when experiments are difficult to lead on a specific material property. It only requires the knowledge of the surface area to volume ratio of the nanomaterial, its size as well as the statistic (Fermi–Dirac or Bose–Einstein) followed by the particles involved in the considered material property. Comparison between different existing theoretical models and the proposed equation is done. PMID:20596422

Role of Morphological Structure, Doping, and Coating of Different Materials in the Sensing Characteristics of Humidity Sensors

PubMed Central

Tripathy, Ashis; Pramanik, Sumit; Cho, Jongman; Santhosh, Jayasree; Osman, Noor Azuan Abu

2014-01-01

The humidity sensing characteristics of different sensing materials are important properties in order to monitor different products or events in a wide range of industrial sectors, research and development laboratories as well as daily life. The primary aim of this study is to compare the sensing characteristics, including impedance or resistance, capacitance, hysteresis, recovery and response times, and stability with respect to relative humidity, frequency, and temperature, of different materials. Various materials, including ceramics, semiconductors, and polymers, used for sensing relative humidity have been reviewed. Correlations of the different electrical characteristics of different doped sensor materials as the most unique feature of a material have been noted. The electrical properties of different sensor materials are found to change significantly with the morphological changes, doping concentration of different materials and film thickness of the substrate. Various applications and scopes are pointed out in the review article. We extensively reviewed almost all main kinds of relative humidity sensors and how their electrical characteristics vary with different doping concentrations, film thickness and basic sensing materials. Based on statistical tests, the zinc oxide-based sensing material is best for humidity sensor design since it shows extremely low hysteresis loss, minimum response and recovery times and excellent stability. PMID:25256110

Fabrication and durable antibacterial properties of 3D porous wet electrospun RCSC/PCL nanofibrous scaffold with silver nanoparticles

NASA Astrophysics Data System (ADS)

Zhang, Mei; Lin, Han; Wang, Yilong; Yang, Guang; Zhao, He; Sun, Dahui

2017-08-01

Electrospunnanofibers are used as three-dimensional (3D) scaffold materials that can alter cell attachment and cell proliferation, change the antibacterial properties of materials, and can be used as wound dressings. But the fabrication of porous 3D scaffold structure and the antibacterial properties enhancing are challenges remained to improve. With the states here, a Ranachensinensis skin collagen (RCSC)/poly(ɛ-caprolactone) (PCL)AgNP-loaded3D nanofiber scaffold is fabricated as a wound dressing material by using an improved wet electrospinning method (blending). The nanoscale of the AgNPs is proved. The 3D porous morphologies of the materials with different AgNP loadings, are determined with field emission scanning electron microscopy (FESEM) and the presence and uniformity distribution of AgNPs is confirmed by Energy dispersive X-ray (EDX) spectroscopy. The silver-ion release rates, antibacterial properties, and cytotoxicities of dressing materials with different AgNP contents are evaluated using ICP-AES, the zone inhibition method, and MTT testing. These results showed that the improved wet electrospun is an effective way to fabricate AgNP loaded 3D scaffold materials with porous structure and nearly 90% porosity and the presence of AgNPs in dressing materials strengthen the antibacterial properties. The RCSC/PCL 3D scaffold materials containing 2.0%AgNP would be promising for dressing materials application nearly without cytotoxicities.

Nonreciprocal Thermal Material by Spatiotemporal Modulation

NASA Astrophysics Data System (ADS)

Torrent, Daniel; Poncelet, Olivier; Batsale, Jean-Chirstophe

2018-03-01

The thermal properties of a material with a spatiotemporal modulation, in the form of a traveling wave, in both the thermal conductivity and the specific heat capacity are studied. It is found that these materials behave as materials with an internal convectionlike term that provides them with nonreciprocal properties, in the sense that the heat flux has different properties when it propagates in the same direction or in the opposite one to the modulation of the parameters. An effective medium description is presented which accurately describes the modulated material, and numerical simulations support this description and verify the nonreciprocal properties of the material. It is found that these materials are promising candidates for the design of thermal diodes and other advanced devices for the control of the heat flow at all scales.

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. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Comparison of Predicted Thermoelectric Energy Conversion Efficiency by Cumulative Properties and Reduced Variables Approaches

NASA Astrophysics Data System (ADS)

Linker, Thomas M.; Lee, Glenn S.; Beekman, Matt

2018-06-01

The semi-analytical methods of thermoelectric energy conversion efficiency calculation based on the cumulative properties approach and reduced variables approach are compared for 21 high performance thermoelectric materials. Both approaches account for the temperature dependence of the material properties as well as the Thomson effect, thus the predicted conversion efficiencies are generally lower than that based on the conventional thermoelectric figure of merit ZT for nearly all of the materials evaluated. The two methods also predict material energy conversion efficiencies that are in very good agreement which each other, even for large temperature differences (average percent difference of 4% with maximum observed deviation of 11%). The tradeoff between obtaining a reliable assessment of a material's potential for thermoelectric applications and the complexity of implementation of the three models, as well as the advantages of using more accurate modeling approaches in evaluating new thermoelectric materials, are highlighted.

Manipulating Ferroelectrics through Changes in Surface and Interface Properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balke, Nina; Ramesh, Ramamoorthy; Yu, Pu

Ferroelectric materials are used in many applications of modern technologies including information storage, transducers, sensors, tunable capacitors, and other novel device concepts. In many of these applications, the ferroelectric properties, such as switching voltages, piezoelectric constants, or stability of nanodomains, are crucial. For any application, even for material characterization, the material itself needs to be interfaced with electrodes. On the basis of the structural, chemical, and electronic properties of the interfaces, the measured material properties can be determined by the interface. This is also true for surfaces. However, the importance of interfaces and surfaces and their effect on experiments aremore » often neglected, which results in many dramatically different experimental results for nominally identical samples. Therefore, it is crucial to understand the role of the interface and surface properties on internal bias fields and the domain switching process. Here, the nanoscale ferroelectric switching process and the stability of nanodomains for Pb(Zr,Ti)O 3 thin films are investigated by using scanning probe microscopy. Interface and surface properties are modulated through the selection/redesign of electrode materials as well as tuning the surface-near oxygen vacancies, which both can result in changes of the electric fields acting across the sample, and consequently this controls the measured ferroelectric and domain retention properties. By understanding the role of surfaces and interfaces, ferroelectric properties can be tuned to eliminate the problem of asymmetric domain stability by combining the effects of different electrode materials. Lastly, this study forms an important step toward integrating ferroelectric materials in electronic devices.« less

Manipulating Ferroelectrics through Changes in Surface and Interface Properties

DOE PAGES

Balke, Nina; Ramesh, Ramamoorthy; Yu, Pu

2017-10-23

Ferroelectric materials are used in many applications of modern technologies including information storage, transducers, sensors, tunable capacitors, and other novel device concepts. In many of these applications, the ferroelectric properties, such as switching voltages, piezoelectric constants, or stability of nanodomains, are crucial. For any application, even for material characterization, the material itself needs to be interfaced with electrodes. On the basis of the structural, chemical, and electronic properties of the interfaces, the measured material properties can be determined by the interface. This is also true for surfaces. However, the importance of interfaces and surfaces and their effect on experiments aremore » often neglected, which results in many dramatically different experimental results for nominally identical samples. Therefore, it is crucial to understand the role of the interface and surface properties on internal bias fields and the domain switching process. Here, the nanoscale ferroelectric switching process and the stability of nanodomains for Pb(Zr,Ti)O 3 thin films are investigated by using scanning probe microscopy. Interface and surface properties are modulated through the selection/redesign of electrode materials as well as tuning the surface-near oxygen vacancies, which both can result in changes of the electric fields acting across the sample, and consequently this controls the measured ferroelectric and domain retention properties. By understanding the role of surfaces and interfaces, ferroelectric properties can be tuned to eliminate the problem of asymmetric domain stability by combining the effects of different electrode materials. Lastly, this study forms an important step toward integrating ferroelectric materials in electronic devices.« less

The Electrical and Optical Properties of Organometal Halide Perovskites Relevant to Optoelectronic Performance.

PubMed

Adinolfi, Valerio; Peng, Wei; Walters, Grant; Bakr, Osman M; Sargent, Edward H

2018-01-01

Organometal halide perovskites are under intense study for use in optoelectronics. Methylammonium and formamidinium lead iodide show impressive performance as photovoltaic materials; a premise that has spurred investigations into light-emitting devices and photodetectors. Herein, the optical and electrical material properties of organometal halide perovskites are reviewed. An overview is given on how the material composition and morphology are tied to these properties, and how these properties ultimately affect device performance. Material attributes and techniques used to estimate them are analyzed for different perovskite materials, with a particular focus on the bandgap, mobility, diffusion length, carrier lifetime, and trap-state density. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Database of Mechanical Properties of Textile Composites

NASA Technical Reports Server (NTRS)

Delbrey, Jerry

1996-01-01

This report describes the approach followed to develop a database for mechanical properties of textile composites. The data in this database is assembled from NASA Advanced Composites Technology (ACT) programs and from data in the public domain. This database meets the data documentation requirements of MIL-HDBK-17, Section 8.1.2, which describes in detail the type and amount of information needed to completely document composite material properties. The database focuses on mechanical properties of textile composite. Properties are available for a range of parameters such as direction, fiber architecture, materials, environmental condition, and failure mode. The composite materials in the database contain innovative textile architectures such as the braided, woven, and knitted materials evaluated under the NASA ACT programs. In summary, the database contains results for approximately 3500 coupon level tests, for ten different fiber/resin combinations, and seven different textile architectures. It also includes a limited amount of prepreg tape composites data from ACT programs where side-by-side comparisons were made.

Loading mode dependent effective properties of octet-truss lattice structures using 3D-printing

NASA Astrophysics Data System (ADS)

Challapalli, Adithya

Cellular materials, often called lattice materials, are increasingly receiving attention for their ultralight structures with high specific strength, excellent impact absorption, acoustic insulation, heat dissipation media and compact heat exchangers. In alignment with emerging additive manufacturing (AM) technology, realization of the structural applications of the lattice materials appears to be becoming faster. Considering the direction dependent material properties of the products with AM, by directionally dependent printing resolution, effective moduli of lattice structures appear to be directionally dependent. In this paper, a constitutive model of a lattice structure, which is an octet-truss with a base material having an orthotropic material property considering AM is developed. In a case study, polyjet based 3D printing material having an orthotropic property with a 9% difference in the principal direction provides difference in the axial and shear moduli in the octet-truss by 2.3 and 4.6%. Experimental validation for the effective properties of a 3D printed octet-truss is done for uniaxial tension and compression test. The theoretical value based on the micro-buckling of truss member are used to estimate the failure strength. Modulus value appears a little overestimate compared with the experiment. Finite element (FE) simulations for uniaxial compression and tension of octettruss lattice materials are conducted. New effective properties for the octet-truss lattice structure are developed considering the observed behavior of the octet-truss structure under macroscopic compression and tension trough simulations.

Measurement of the trapping and detrapping properties of polymers in relation with their microstructure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vallayer, B.; Hourquebie, P.; Marsacq, D.

1996-12-31

In the field of Space Charge Physics, the role of electrical traps on space charge behavior and therefore on the breakdown properties has been now well-established. However, the traps in polymers are very difficult to define compared to the case of ceramics for which a lot of studies have been performed. A new specific method for measuring the trapping and detrapping properties of dielectric materials has been developed. This method allows to characterize the electrostatic state of an insulating sample after irradiation by a high energy electron beam. The authors discuss the basis of the method and its general possibilitiesmore » to measure the breakdown relevant parameters as the secondary electron yield for instance. Moreover, the method has been used on several polymers as HDPE and LDPE. The difference of trapping properties between those materials can be explained by microstructure evolutions (crystallinity ratio) due to a difference of the branching rate. This difference of trapping and detrapping properties of these two polymers could be connected to the breakdown behavior of the two materials which is known to be very different.« less

A study of the effect of selected material properties on the ablation performance of artificial graphite

NASA Technical Reports Server (NTRS)

Maahs, H. G.

1972-01-01

Eighteen material properties were measured on 45 different, commercially available, artificial graphites. Ablation performance of these same graphites were also measured in a Mach 2 airstream at a stagnation pressure of 5.6 atm. Correlations were developed, where possible, between pairs of the material properties. Multiple regression equations were then formulated relating ablation performance to the various material properties, thus identifying those material properties having the strongest effect on ablation performance. These regression equations reveal that ablation performance in the present test environment depends primarily on maximum grain size, density, ash content, thermal conductivity, and mean pore radius. For optimization of ablation performance, grain size should be small, ash content low, density and thermal conductivity high, and mean pore radius large.

Theoretical study on the electronic and optical properties of bulk and surface (001) InxGa1-xAs

NASA Astrophysics Data System (ADS)

Liu, XueFei; Ding, Zhao; Luo, ZiJiang; Zhou, Xun; Wei, JieMin; Wang, Yi; Guo, Xiang; Lang, QiZhi

2018-05-01

The optical properties of surface and bulk InxGa1-xAs materials are compared systematically first time in this paper. The band structures, density of states and optical properties including dielectric function, reflectivity, absorption coefficient, loss function and refractive index of bulk and surface InxGa1-xAs materials are investigated by first-principles based on plane-wave pseudo-potentials method within the LDA approximation. The results agree well with the available theoretical and experimental studies and indicate that the electronic and optical properties of bulk and surface InxGa1-xAs materials are much different, and the results show that the considered optical properties of the both materials vary with increasing indium composition in an opposite way. The calculations show that the optical properties of surface In0.75Ga0.25As material are unexpected to be far from the other two indium compositions of surface InxGa1-xAs materials while the optical properties of bulk InxGa1-xAs materials vary with increasing indium composition in an expected regular way.

Effect of Injection Molding Melt Temperatures on PLGA Craniofacial Plate Properties during In Vitro Degradation.

PubMed

de Melo, Liliane Pimenta; Salmoria, Gean Vitor; Fancello, Eduardo Alberto; Roesler, Carlos Rodrigo de Mello

2017-01-01

The purpose of this article is to present mechanical and physicochemical properties during in vitro degradation of PLGA material as craniofacial plates based on different values of injection molded temperatures. Injection molded plates were submitted to in vitro degradation in a thermostat bath at 37 ± 1°C by 16 weeks. The material was removed after 15, 30, 60, and 120 days; then bending stiffness, crystallinity, molecular weights, and viscoelasticity were studied. A significant decrease of molecular weight and mechanical properties over time and a difference in FT-IR after 60 days showed faster degradation of the material in the geometry studied. DSC analysis confirmed that the crystallization occurred, especially in higher melt temperature condition. DMA analysis suggests a greater contribution of the viscous component of higher temperature than lower temperature in thermomechanical behavior. The results suggest that physical-mechanical properties of PLGA plates among degradation differ per injection molding temperatures.

A blueprint for the synthesis and characterisation of thin graphene oxide with controlled lateral dimensions for biomedicine

NASA Astrophysics Data System (ADS)

Filipe Rodrigues, Artur; Newman, Leon; Lozano, Neus; Mukherjee, Sourav P.; Fadeel, Bengt; Bussy, Cyrill; Kostarelos, Kostas

2018-07-01

Graphene-based materials (GBMs) have ignited a revolution in material science and technology, with electronic, optical and mechanical properties that are of relevant interest for a wide range of applications. To support the development of these enabling technologies, a global research effort has been invested to assess their hazard and biocompatibility. Different production methods have however generated a diverse collection of GBMs with different physicochemical properties, leading to a variety of biological outcomes that are still not fully understood. To better understand the biological interactions of GBMs with biological systems and allow the design of safer materials, a thorough physicochemical characterisation is therefore highly recommended. The aim of the present work was to produce a blueprint for the synthesis and characterisation of non-pyrogenic graphene oxide (GO) flakes with three different controlled lateral dimensions, which could be further used for either hazard assessment or biomedical proof-of-concept studies. A battery of techniques used to characterise the physicochemical properties of the GO samples included atomic force microscopy, transmission electron microscopy, Fourier-transformed infra-red spectroscopy, x-ray photoelectron spectroscopy and Raman spectroscopy. The combination of these different techniques confirmed that only the lateral dimension varied among the GO materials produced, without significant change in any other of their fundamental physicochemical properties, such as the thickness or surface chemistry. The proposed systematic approach in GO batch production for biology will hopefully contribute to a better understanding of the material properties that govern their interactions with biological systems and offer a blueprint towards standardisation of biologically relevant 2D materials.

Study of different roles phosphorescent material played in different positions of organic light emitting diodes

NASA Astrophysics Data System (ADS)

Keke, Gu; Jian, Zhong; Jiule, Chen; Yucheng, Chen; Ming, Deng

2013-09-01

Phosphorescent materials are crucial to improve the luminescence and efficiency of organic light emitting diodes (OLED), because its internal quantum efficiency can reach 100%. So the studying of optical and electrical properties of phosphorescent materials is propitious for the further development of phosphorescent OLED. Phosphorescent materials were generally doped into different host materials as emitting components, not only played an important role in emitting light but also had a profound influence on carrier transport properties. We studied the optical and electrical properties of the blue 4,4'-bis(2,2-diphenylvinyl)-1,1'-biphenyl (DPVBi)-based devices, adding a common yellow phosphorescent material bis[2-(4- tert-butylphenyl)benzothiazolato- N,C2'] iridium(acetylacetonate) [( t-bt)2Ir(acac)] in different positions. The results showed ( t-bt)2Ir(acac) has remarkable hole-trapping ability. Especially the ultrathin structure device, compared to the device without ( t-bt)2Ir(acac), had increased the luminance by about 60%, and the efficiency by about 97%. Then introduced thin 4,4'-bis(carbazol-9-yl)biphenyl (CBP) host layer between DPVBi and ( t-bt)2Ir(acac), and got devices with stable white color.

The electrical properties of zero-gravity processed immiscibles

NASA Technical Reports Server (NTRS)

Lacy, L. L.; Otto, G. H.

1974-01-01

When dispersed or mixed immiscibles are solidified on earth, a large amount of separation of the constituents takes place due to differences in densities. However, when the immiscibles are dispersed and solidified in zero-gravity, density separation does not occur, and unique composite solids can be formed with many new and promising electrical properties. By measuring the electrical resistivity and superconducting critical temperature, Tc, of zero-g processed Ga-Bi samples, it has been found that the electrical properties of such materials are entirely different from the basic constituents and the ground control samples. Our results indicate that space processed immiscible materials may form an entirely new class of electronic materials.

Establishment of gel materials with different mechanical properties by 3D gel printer SWIM-ER

NASA Astrophysics Data System (ADS)

Ota, Takafumi; Tase, Taishi; Okada, Koji; Saito, Azusa; Takamatsu, Kyuuichiro; Kawakami, Masaru; Furukawa, Hidemitsu

2016-04-01

A 3D printer is a device which can directly produce objects whose shape is the same as the original 3D digital data. Hydrogels have unique properties such as high water content, low frictional properties, biocompatibility, material permeability and high transparency, which are rare in hard and dry materials. These superior characteristics of gels promise useful medical applications. We have been working on the development of a 3D gel printer, SWIM-ER (Soft and Wet Industrial - Easy Realizer), which can make models of organs and artificial blood vessels with gel material. However, 3D printing has a problem: the mechanical properties of the printed object vary depending on printing conditions, and this matter was investigated with SWIM-ER. In the past, we found that mechanical properties of 3D gel objects depend on the deposition orientation in SWIM-ER. In this study, gels were printed with different laser scanning speeds. The mechanical properties of these gels were investigated by compression tests, water content measurements and SMILS (Scanning Microscopic Light Scattering).

Method for measuring thermal properties using a long-wavelength infrared thermal image

DOEpatents

Walker, Charles L [Albuquerque, NM; Costin, Laurence S [Albuquerque, NM; Smith, Jody L [Albuquerque, NM; Moya, Mary M [Albuquerque, NM; Mercier, Jeffrey A [Albuquerque, NM

2007-01-30

A method for estimating the thermal properties of surface materials using long-wavelength thermal imagery by exploiting the differential heating histories of ground points in the vicinity of shadows. The use of differential heating histories of different ground points of the same surface material allows the use of a single image acquisition step to provide the necessary variation in measured parameters for calculation of the thermal properties of surface materials.

Study of Fresh and Hardening Process Properties of Gypsum with Three Different PCM Inclusion Methods

PubMed Central

Serrano, Susana; Barreneche, Camila; Navarro, Antonia; Haurie, Laia; Fernandez, A. Inés; Cabeza, Luisa F.

2015-01-01

Gypsum has two important states (fresh and hardened states), and the addition of phase change materials (PCM) can vary the properties of the material. Many authors have extensively studied properties in the hardened state; however, the variation of fresh state properties due to the addition of Micronal® DS 5001 X PCM into gypsum has been the object of few investigations. Properties in fresh state define the workability, setting time, adherence and shrinkage, and, therefore the possibility of implementing the material in building walls. The aim of the study is to analyze, compare and evaluate the variability of fresh state properties after the inclusion of 10% PCM. PCM are added into a common gypsum matrix by three different methods: adding microencapsulated PCM, making a suspension of PCM/water, and incorporating PCM through a vacuum impregnation method. Results demonstrate that the inclusion of PCM change completely the water required by the gypsum to achieve good workability, especially the formulation containing Micronal® DS 5001 X: the water required is higher, the retraction is lower (50% less) due to the organic nature of the PCM with high elasticity and, the adherence is reduced (up to 45%) due to the difference between the porosity of the different surfaces as well as the surface tension difference. PMID:28793584

Development of Fe/Nb-based solar photocatalysts for water treatment: impact of different synthesis routes on materials properties.

PubMed

Ribeiro, Marília C M; Amorim, Camila C; Moreira, Regina F P M; Oliveira, Luiz C A; Henriques, Andréia B; Leão, Mônica M D

2018-04-27

Semiconductors based on Fe/Nb oxides can present both solar sensitivity and high catalytic activity. However, there is still a lack regarding the comparison between different routes to produce Fe/Nb-based solar photocatalysts and the evaluation of the impact of the synthesis operating conditions on the material properties. In this work, Fe/Nb 2 O 5 ratio, type of precipitating agent, presence/absence of washing stage, and temperature of calcination were verified to be the most relevant parameters in the synthesis by the co-precipitation method. These factors led to remarkable differences in the properties and performance of the photocatalysts produced by each distinct synthesis route. Composition, iron species present in the materials, crystallinity characteristics, and pH of the catalysts were affected, leading to different photocatalytic activities under UV-Vis light. Due to their characteristics, the synthesized materials are potential photocatalysts for application in solar processes. Graphical abstract ᅟ.

Effects of mechanical properties of thermoplastic materials on the initial force of thermoplastic appliances.

PubMed

Kohda, Naohisa; Iijima, Masahiro; Muguruma, Takeshi; Brantley, William A; Ahluwalia, Karamdeep S; Mizoguchi, Itaru

2013-05-01

To measure the forces delivered by thermoplastic appliances made from three materials and investigate effects of mechanical properties, material thickness, and amount of activation on orthodontic forces. Three thermoplastic materials, Duran (Scheu Dental), Erkodur (Erkodent Erich Kopp GmbH), and Hardcast (Scheu Dental), with two different thicknesses were selected. Values of elastic modulus and hardness were obtained from nanoindentation measurements at 28°C. A custom-fabricated system with a force sensor was employed to obtain measurements of in vitro force delivered by the thermoplastic appliances for 0.5-mm and 1.0-mm activation for bodily tooth movement. Experimental results were subjected to several statistical analyses. Hardcast had significantly lower elastic modulus and hardness than Duran and Erkodur, whose properties were not significantly different. Appliances fabricated from thicker material (0.75 mm or 0.8 mm) always produced significantly greater force than those fabricated from thinner material (0.4 mm or 0.5 mm). Appliances with 1.0-mm activation produced significantly lower force than those with 0.5-mm activation, except for 0.4-mm thick Hardcast appliances. A strong correlation was found between mechanical properties of the thermoplastic materials and force produced by the appliances. Orthodontic forces delivered by thermoplastic appliances depend on the material, thickness, and amount of activation. Mechanical properties of the polymers obtained by nanoindentation testing are predictive of force delivery by these appliances.

Influence of raw material properties upon critical quality attributes of continuously produced granules and tablets.

PubMed

Fonteyne, Margot; Wickström, Henrika; Peeters, Elisabeth; Vercruysse, Jurgen; Ehlers, Henrik; Peters, Björn-Hendrik; Remon, Jean Paul; Vervaet, Chris; Ketolainen, Jarkko; Sandler, Niklas; Rantanen, Jukka; Naelapää, Kaisa; De Beer, Thomas

2014-07-01

Continuous manufacturing gains more and more interest within the pharmaceutical industry. The International Conference of Harmonisation (ICH) states in its Q8 'Pharmaceutical Development' guideline that the manufacturer of pharmaceuticals should have an enhanced knowledge of the product performance over a range of raw material attributes, manufacturing process options and process parameters. This fits further into the Process Analytical Technology (PAT) and Quality by Design (QbD) framework. The present study evaluates the effect of variation in critical raw material properties on the critical quality attributes of granules and tablets, produced by a continuous from-powder-to-tablet wet granulation line. The granulation process parameters were kept constant to examine the differences in the end product quality caused by the variability of the raw materials properties only. Theophylline-Lactose-PVP (30-67.5-2.5%) was used as model formulation. Seven different grades of theophylline were granulated. Afterward, the obtained granules were tableted. Both the characteristics of granules and tablets were determined. The results show that differences in raw material properties both affect their processability and several critical quality attributes of the resulting granules and tablets. Copyright © 2014 Elsevier B.V. All rights reserved.

Correlation of microstructure and thermo-mechanical properties of a novel hydrogen transport membrane

NASA Astrophysics Data System (ADS)

Zhang, Yongjun

A key part of the FutureGen concept is to support the production of hydrogen to fuel a "hydrogen economy," with the use of clean burning hydrogen in power-producing fuel cells, as well as for use as a transportation fuel. One of the key technical barriers to FutureGen deployment is reliable and efficient hydrogen separation technology. Most Hydrogen Transport Membrane (HTM) research currently focuses on separation technology and hydrogen flux characterization. No significant work has been performed on thermo-mechanical properties of HTMs. The objective of the thesis is to understand the structure-property correlation of HTM and to characterize (1) thermo mechanical properties under different reducing environments and thermal cycles (thermal shock), and (2) evaluate the stability of the novel HTM material. A novel HTM cermet bulk sample was characterized for its physical and mechanical properties at both room temperature and at elevated temperature up to 1000°C. Micro-structural properties and residual stresses were evaluated in order to understand the changing mechanism of the microstructure and its effects on the mechanical properties of materials. A correlation of the microstructural and thermo mechanical properties of the HTM system was established for both HTM and the substrate material. Mechanical properties of both selected structural ceramics and the novel HTM cermet bulk sample are affected mainly by porosity and microstructural features, such as grain size and pore size-distribution. The Young's Modulus (E-value) is positively correlated to the flexural strength for materials with similar crystallographic structure. However, for different crystallographic materials, physical properties are independent of mechanical properties. Microstructural properties, particularly, grain size and crystallographic structure, and thermodynamic properties are the main factors affecting the mechanical properties at both room and high temperatures. The HTM cermet behaves more like an elastic material at room temperature and as a ductile material at temperature above 850°C. The oxidation and the plasticity of Pd phase mainly affected the mechanical properties of HTM cermet at high temperature, also as a result of thermal cycling. Residual stress induced in the HTM by thermo cycles also plays a very critical role in defining the thermo-mechanical properties.

Effect of spatial restriction on the photoluminescent properties of carbon nanomaterials

NASA Astrophysics Data System (ADS)

Vostrikova, A. M.; Nikolaeva, A. N.; Bakal, A. A.; Shpuntova, D. V.; Mordovina, E. A.; Sukhorukov, G. B.; Sapelkin, A. V.; Goryacheva, I. Yu.

2018-04-01

Photoluminescent (PL) properties of carbon-based nanomaterials obtained on the base of sodium dextran sulfate (DS) were compared. DS water solution, dry powder and co-precipitated inside pores of CaCO3 microparticles solution were thermally treated and clear difference between these materials was found. Effect of spatial restriction of CaCO3 pores showed itself in the identity of PL properties for material, obtained by thermal and hydrothermal treatment; in the absence of CaCO3 microparticles the PL spectra were quite different.

Comparative study of mechanical properties of direct core build-up materials

PubMed Central

Kumar, Girish; Shivrayan, Amit

2015-01-01

Background and Objectives: The strength greatly influences the selection of core material because core must withstand forces due to mastication and para-function for many years. This study was conducted to evaluate certain mechanical properties of commonly used materials for direct core build-up, including visible light cured composite, polyacid modified composite, resin modified glass ionomer, high copper amalgam, and silver cermet cement. Materials and Methods: All the materials were manipulated according to the manufacturer's recommendations and standard test specimens were prepared. A universal testing machine at different cross-head speed was used to determine all the four mechanical properties. Mean compressive strength, diametral tensile strength, flexural strength, and elastic modulus with standard deviations were calculated. Multiple comparisons of the materials were also done. Results: Considerable differences in compressive strength, diametral tensile strength, and flexural strength were observed. Visible light cured composite showed relatively high compressive strength, diametral tensile strength, and flexural strength compared with the other tested materials. Amalgam showed the highest value for elastic modulus. Silver cermet showed less value for all the properties except for elastic modulus. Conclusions: Strength is one of the most important criteria for selection of a core material. Stronger materials better resist deformation and fracture provide more equitable stress distribution, greater stability, and greater probability of clinical success. PMID:25684905

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.

Mechanical Properties of Air Plasma Sprayed Environmental Barrier Coating (EBC) Materials

NASA Technical Reports Server (NTRS)

Richards, Bradley; Zhu, Dongming; Ghosn, Louis; Wadley, Haydn

2015-01-01

Development work in Environmental Barrier Coatings (EBCs) for Ceramic Matrix Composites (CMCs) has focused considerably on the identification of materials systems and coating architectures to meet application needs. The evolution of these systems has occurred so quickly that modeling efforts and requisite data for modeling lag considerably behind development. Materials property data exists for many systems in the bulk form, but the effects of deposition on the critical properties of strength and fracture behavior are not well studied. We have plasma sprayed bulk samples of baseline EBC materials (silicon, ytterbium disilicate) and tested the mechanical properties of these materials to elicit differences in strength and toughness. We have also endeavored to assess the mixed-mode fracture resistance, Gc, of silicon in a baseline EBC applied to SiCSiC CMC via four point bend test. These results are compared to previously determined properties of the comparable bulk material.

Microstructure and mechanical properties of horns derived from three domestic bovines.

PubMed

Zhang, Quan-bin; Li, Chun; Pan, Yan-ting; Shan, Guang-hua; Cao, Ping; He, Jia; Lin, Zhong-shi; Ao, Ning-jian; Huang, Yao-xiong

2013-12-01

The microstructure and mechanical properties of horns derived from three domestic bovines (buffalo, cattle and sheep) were examined. The effects of water content, sampling position and orientation of three bovid horns on mechanical properties were systematically investigated by uniaxial tension and micron indentation tests. Meanwhile, the material composition and metal element contents were determined by Raman spectroscopy and elemental analysis respectively, and the microstructures of the horns were measured by scanning electron microscopy (SEM). Results show that the mechanical properties of horns have negative correlation with water contents and depend on sampling position and orientation. The spatial variations of the mechanical properties in horns are attributed to the different keratinization degrees in the proximal, middle and distal parts. And the mechanical properties of horns in the longitudinal direction are better than those in transverse. Among the three kinds of horns, the mechanical properties of buffalo horn are the best, followed by cattle horn, and those in sheep horn are the worst. This is due to the differences in material composition, metal element, and the microstructures of the horns. But the mechanical properties of buffalo horns are not dependent on the source of the buffalo. Therefore, regular engineered buffalo keratinous materials with standard mechanical properties can be obtained from different buffalo horns by using proper preparation methods. © 2013.

In vivo bone strain in the mandibular corpus of Sapajus during a range of oral food processing behaviors.

PubMed

Ross, Callum F; Iriarte-Diaz, Jose; Reed, David A; Stewart, Thomas A; Taylor, Andrea B

2016-09-01

It has been hypothesized that mandibular corpus morphology of primates is related to the material properties of the foods that they chew. However, chewing foods with different material properties is accompanied by low levels of variation in mandibular strain patterns in macaques. We hypothesized that if variation in primate mandible form reflects adaptations to feeding on foods with different material and geometric properties, then this variation will be driven primarily by differences in oral food processing behavior rather than differences in chewing per se. To test this hypothesis, we recorded in vivo bone strain data from the lateral and medial surfaces of the mandibular corpus during complete feeding sequences in three adult male Sapajus as they fed on foods with a range of sizes and material properties. We assessed whether variation in mandibular corpus strain regimes is associated with variation in feeding behaviors and/or chewing on different foods, and we quantified the relative variation in mandibular corpus strain regimes associated with chewing on foods of different material properties versus a range of oral food processing behaviors (incisor, premolar, and molar biting; pulling on incisors; mastication). Feeding behavior had a significant effect on mandibular corpus strain regimes, as did chewing side and the cycle number in a feeding sequence. However, food type had weaker effects and usually only through interaction effects with chewing side and/or cycle type. Strain regimes varied most across different chew sides, then across different behaviors, and lastly between mastication cycles on different foods. Strain magnitudes associated with premolar, molar, and incisor biting were larger than those recorded during mastication. These data suggest that intra- and inter-specific variation in mandible morphology is a trade-off between performance requirements of different oral food processing behaviors and of variation in chewing side, with direct effects of food type being less important. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of the material properties on the crumpling of a thin sheet.

PubMed

Habibi, Mehdi; Adda-Bedia, Mokhtar; Bonn, Daniel

2017-06-07

While simple at first glance, the dense packing of sheets is a complex phenomenon that depends on material parameters and the packing protocol. We study the effect of plasticity on the crumpling of sheets of different materials by performing isotropic compaction experiments on sheets of different sizes and elasto-plastic properties. First, we quantify the material properties using a dimensionless foldability index. Then, the compaction force required to crumple a sheet into a ball as well as the average number of layers inside the ball are measured. For each material, both quantities exhibit a power-law dependence on the diameter of the crumpled ball. We experimentally establish the power-law exponents and find that both depend nonlinearly on the foldability index. However the exponents that characterize the mechanical response and morphology of the crumpled materials are related linearly. A simple scaling argument explains this in terms of the buckling of the sheets, and recovers the relation between the crumpling force and the morphology of the crumpled structure. Our results suggest a new approach to tailor the mechanical response of the crumpled objects by carefully selecting their material properties.

A Microwave Thermostatic Reactor for Processing Liquid Materials Based on a Heat-Exchanger.

PubMed

Zhou, Yongqiang; Zhang, Chun; Xie, Tian; Hong, Tao; Zhu, Huacheng; Yang, Yang; Liu, Changjun; Huang, Kama

2017-10-08

Microwaves have been widely used in the treatment of different materials. However, the existing adjustable power thermostatic reactors cannot be used to analyze materials characteristics under microwave effects. In this paper, a microwave thermostatic chemical reactor for processing liquid materials is proposed, by controlling the velocity of coolant based on PLC (programmable logic controller) in different liquid under different constant electric field intensity. A nonpolar coolant (Polydimethylsiloxane), which is completely microwave transparent, is employed to cool the liquid materials. Experiments are performed to measure the liquid temperature using optical fibers, the results show that the precision of temperature control is at the range of ±0.5 °C. Compared with the adjustable power thermostatic control system, the effect of electric field changes on material properties are avoided and it also can be used to detect the properties of liquid materials and special microwave effects.

A Microwave Thermostatic Reactor for Processing Liquid Materials Based on a Heat-Exchanger

PubMed Central

Zhou, Yongqiang; Zhang, Chun; Xie, Tian; Hong, Tao; Yang, Yang; Liu, Changjun; Huang, Kama

2017-01-01

Microwaves have been widely used in the treatment of different materials. However, the existing adjustable power thermostatic reactors cannot be used to analyze materials characteristics under microwave effects. In this paper, a microwave thermostatic chemical reactor for processing liquid materials is proposed, by controlling the velocity of coolant based on PLC (programmable logic controller) in different liquid under different constant electric field intensity. A nonpolar coolant (Polydimethylsiloxane), which is completely microwave transparent, is employed to cool the liquid materials. Experiments are performed to measure the liquid temperature using optical fibers, the results show that the precision of temperature control is at the range of ±0.5 °C. Compared with the adjustable power thermostatic control system, the effect of electric field changes on material properties are avoided and it also can be used to detect the properties of liquid materials and special microwave effects. PMID:28991195

Raman Mapping for the Investigation of Nano-phased Materials

NASA Astrophysics Data System (ADS)

Gouadec, G.; Bellot-Gurlet, L.; Baron, D.; Colomban, Ph.

Nanosized and nanophased materials exhibit special properties. First they offer a good compromise between the high density of chemical bonds by unit volume, needed for good mechanical properties and the homogeneity of amorphous materials that prevents crack initiation. Second, interfaces are in very high concentration and they have a strong influence on many electrical and redox properties. The analysis of nanophased, low crystallinity materials is not straigtforward. The recording of Raman spectra with a geometric resolution close to 0.5 \\upmu {text{ m}^3} and the deep understanding of the Raman signature allow to locate the different nanophases and to predict the properties of the material. Case studies are discussed: advanced polymer fibres, ceramic fibres and composites, textured piezoelectric ceramics and corroded (ancient) steel.

Important physical properties of peat materials

Treesearch

D.H. Boelter

1968-01-01

Peat materials from 12 bogs in northern Minnesota, U.S.A., showed significant differences in physical properties. It is pointed out that 1) these properties can be related to the hydrology of organic soils only if the soils represent undisturbed field conditions, and 2) volumetric expressions of water content are necessary to correctly evaluate the amount of water in a...

Prediction of Fracture Behavior in Rock and Rock-like Materials Using Discrete Element Models

NASA Astrophysics Data System (ADS)

Katsaga, T.; Young, P.

2009-05-01

The study of fracture initiation and propagation in heterogeneous materials such as rock and rock-like materials are of principal interest in the field of rock mechanics and rock engineering. It is crucial to study and investigate failure prediction and safety measures in civil and mining structures. Our work offers a practical approach to predict fracture behaviour using discrete element models. In this approach, the microstructures of materials are presented through the combination of clusters of bonded particles with different inter-cluster particle and bond properties, and intra-cluster bond properties. The geometry of clusters is transferred from information available from thin sections, computed tomography (CT) images and other visual presentation of the modeled material using customized AutoCAD built-in dialog- based Visual Basic Application. Exact microstructures of the tested sample, including fractures, faults, inclusions and void spaces can be duplicated in the discrete element models. Although the microstructural fabrics of rocks and rock-like structures may have different scale, fracture formation and propagation through these materials are alike and will follow similar mechanics. Synthetic material provides an excellent condition for validating the modelling approaches, as fracture behaviours are known with the well-defined composite's properties. Calibration of the macro-properties of matrix material and inclusions (aggregates), were followed with the overall mechanical material responses calibration by adjusting the interfacial properties. The discrete element model predicted similar fracture propagation features and path as that of the real sample material. The path of the fractures and matrix-inclusion interaction was compared using computed tomography images. Initiation and fracture formation in the model and real material were compared using Acoustic Emission data. Analysing the temporal and spatial evolution of AE events, collected during the sample testing, in relation to the CT images allows the precise reconstruction of the failure sequence. Our proposed modelling approach illustrates realistic fracture formation and growth predictions at different loading conditions.

Investigation into improved pavement curing materials and techniques : part 2 (phase III).

DOT National Transportation Integrated Search

2003-03-01

Appropriate curing is important for concrete to obtain the designed properties. This research was conducted to evaluate the curing : effects of different curing materials and methods on pavement properties. At present the sprayed curing compound is a...

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.

Non-destructive research methods applied on materials for the new generation of nuclear reactors

NASA Astrophysics Data System (ADS)

Bartošová, I.; Slugeň, V.; Veterníková, J.; Sojak, S.; Petriska, M.; Bouhaddane, A.

2014-06-01

The paper is aimed on non-destructive experimental techniques applied on materials for the new generation of nuclear reactors (GEN IV). With the development of these reactors, also materials have to be developed in order to guarantee high standard properties needed for construction. These properties are high temperature resistance, radiation resistance and resistance to other negative effects. Nevertheless the changes in their mechanical properties should be only minimal. Materials, that fulfil these requirements, are analysed in this work. The ferritic-martensitic (FM) steels and ODS steels are studied in details. Microstructural defects, which can occur in structural materials and can be also accumulated during irradiation due to neutron flux or alpha, beta and gamma radiation, were analysed using different spectroscopic methods as positron annihilation spectroscopy and Barkhausen noise, which were applied for measurements of three different FM steels (T91, P91 and E97) as well as one ODS steel (ODS Eurofer).

Visualizing Earth Materials

NASA Astrophysics Data System (ADS)

Cashman, K. V.; Rust, A.; Stibbon, E.; Harris, R.

2016-12-01

Earth materials are fundamental to art. They are pigments, they are clay, they provide form and color. Earth scientists, however, rarely attempt to make the physical properties of Earth materials visible through art, and similarly many artists use Earth materials without fully understanding their physical and chemical properties. Here we explore the intersection between art and science through study of the physical properties of Earth materials as characterized in the laboratory, and as transferred to paper using different techniques and suspending media. One focus of this collaboration is volcanic ash. Ash is interesting scientifically because its form provides information on the fundamental processes that drive volcanic eruptions, and determines its transport properties, and thus its potential to affect populations far downwind of the volcano. Ash properties also affect its behavior as an art material. From an aesthetic point of view, ash lends a granular surface to the image; it is also uncontrollable, and thus requires engagement between artist and medium. More fundamentally, using ash in art creates an exchange between the medium and the subject matter, and imparts something of the physical, visceral experience of volcanic landscapes to the viewer. Another component of this work uses powdered rock as a printing medium for geologic maps. Because different types of rock create powders with different properties (grain size distributions and shapes), the geology is communicated not only as color, but also by the physical characteristics of the material as it interacts with the paper. More importantly, the use of actual rocks samples as printing material for geologic maps not only makes a direct connection between the map and the material it represents, but also provides an emotional connection between the map, the viewer and the landscape, its colors, textures and geological juxtapositions. Both case studies provide examples not only of ways in which artists can help scientists to visualize materials, but also how artists and scientists can work together to learn from each other. To illustrate this point, our poster will provide opportunities for hands on experimentation with earth materials as artistic media.

Photonics and optoelectronics of two-dimensional materials beyond graphene.

PubMed

Ponraj, Joice Sophia; Xu, Zai-Quan; Dhanabalan, Sathish Chander; Mu, Haoran; Wang, Yusheng; Yuan, Jian; Li, Pengfei; Thakur, Siddharatha; Ashrafi, Mursal; Mccoubrey, Kenneth; Zhang, Yupeng; Li, Shaojuan; Zhang, Han; Bao, Qiaoliang

2016-11-18

Apart from conventional materials, the study of two-dimensional (2D) materials has emerged as a significant field of study for a variety of applications. Graphene-like 2D materials are important elements of potential optoelectronics applications due to their exceptional electronic and optical properties. The processing of these materials towards the realization of devices has been one of the main motivations for the recent development of photonics and optoelectronics. The recent progress in photonic devices based on graphene-like 2D materials, especially topological insulators (TIs) and transition metal dichalcogenides (TMDs) with the methodology level discussions from the viewpoint of state-of-the-art designs in device geometry and materials are detailed in this review. We have started the article with an overview of the electronic properties and continued by highlighting their linear and nonlinear optical properties. The production of TIs and TMDs by different methods is detailed. The following main applications focused towards device fabrication are elaborated: (1) photodetectors, (2) photovoltaic devices, (3) light-emitting devices, (4) flexible devices and (5) laser applications. The possibility of employing these 2D materials in different fields is also suggested based on their properties in the prospective part. This review will not only greatly complement the detailed knowledge of the device physics of these materials, but also provide contemporary perception for the researchers who wish to consider these materials for various applications by following the path of graphene.

Photonics and optoelectronics of two-dimensional materials beyond graphene

NASA Astrophysics Data System (ADS)

Ponraj, Joice Sophia; Xu, Zai-Quan; Chander Dhanabalan, Sathish; Mu, Haoran; Wang, Yusheng; Yuan, Jian; Li, Pengfei; Thakur, Siddharatha; Ashrafi, Mursal; Mccoubrey, Kenneth; Zhang, Yupeng; Li, Shaojuan; Zhang, Han; Bao, Qiaoliang

2016-11-01

Apart from conventional materials, the study of two-dimensional (2D) materials has emerged as a significant field of study for a variety of applications. Graphene-like 2D materials are important elements of potential optoelectronics applications due to their exceptional electronic and optical properties. The processing of these materials towards the realization of devices has been one of the main motivations for the recent development of photonics and optoelectronics. The recent progress in photonic devices based on graphene-like 2D materials, especially topological insulators (TIs) and transition metal dichalcogenides (TMDs) with the methodology level discussions from the viewpoint of state-of-the-art designs in device geometry and materials are detailed in this review. We have started the article with an overview of the electronic properties and continued by highlighting their linear and nonlinear optical properties. The production of TIs and TMDs by different methods is detailed. The following main applications focused towards device fabrication are elaborated: (1) photodetectors, (2) photovoltaic devices, (3) light-emitting devices, (4) flexible devices and (5) laser applications. The possibility of employing these 2D materials in different fields is also suggested based on their properties in the prospective part. This review will not only greatly complement the detailed knowledge of the device physics of these materials, but also provide contemporary perception for the researchers who wish to consider these materials for various applications by following the path of graphene.

Tribological properties of hydraulic fluids modified by peat-based additives

NASA Astrophysics Data System (ADS)

Ionov, V. V.; Larionov, S. A.; Sarkisov, Ju S.; Kopanica, N. O.; Gorchkova, A. V.; Gorlenko, N. P.; Tzevtkov, N. A.; Ikonnikova, K. V.

2017-02-01

The paper presents physicochemical investigations of the structure and properties of a nano-modifier synthesized from peat, the local raw material subjected to pyrolysis in air-free conditions. This nano-modifying additive is a combination of various forms of nanocarbon and polar and non-polar adsorbing materials such as silica (SiO2), calcium carbonate (CaCO3) and carbon (C). Different nanocarbon forms (nanotubes, fullerenes, nanodiamonds, nanofiber, nanodispersed carbon) used in different proportions with micro and macro peat components give multifunctional properties to the synthesized nano-modifier and the ability to positively change tribological properties of hydraulic fluids and oil lubricants. Test results of type TMT-600 show that its different percentage is required to modify tribological properties of the steel tribocouple under different loading conditions. At 0.5 wt.% content of this nano-modifier, stabilization of the friction ratio and an increase of seizure load are observed.

Optical characterization of tissue mimicking phantoms by a vertical double integrating sphere system

NASA Astrophysics Data System (ADS)

Han, Yilin; Jia, Qiumin; Shen, Shuwei; Liu, Guangli; Guo, Yuwei; Zhou, Ximing; Chu, Jiaru; Zhao, Gang; Dong, Erbao; Allen, David W.; Lemaillet, Paul; Xu, Ronald

2016-03-01

Accurate characterization of absorption and scattering properties for biologic tissue and tissue-simulating materials enables 3D printing of traceable tissue-simulating phantoms for medical spectral device calibration and standardized medical optical imaging. Conventional double integrating sphere systems have several limitations and are suboptimal for optical characterization of liquid and soft materials used in 3D printing. We propose a vertical double integrating sphere system and the associated reconstruction algorithms for optical characterization of phantom materials that simulate different human tissue components. The system characterizes absorption and scattering properties of liquid and solid phantom materials in an operating wavelength range from 400 nm to 1100 nm. Absorption and scattering properties of the phantoms are adjusted by adding titanium dioxide powder and India ink, respectively. Different material compositions are added in the phantoms and characterized by the vertical double integrating sphere system in order to simulate the human tissue properties. Our test results suggest that the vertical integrating sphere system is able to characterize optical properties of tissue-simulating phantoms without precipitation effect of the liquid samples or wrinkling effect of the soft phantoms during the optical measurement.

Application of Calcium Phosphate Materials in Dentistry

PubMed Central

Al-Sanabani, Jabr S.; Al-Sanabani, Fadhel A.

2013-01-01

Calcium phosphate materials are similar to bone in composition and in having bioactive and osteoconductive properties. Calcium phosphate materials in different forms, as cements, composites, and coatings, are used in many medical and dental applications. This paper reviews the applications of these materials in dentistry. It presents a brief history, dental applications, and methods for improving their mechanical properties. Notable research is highlighted regarding (1) application of calcium phosphate into various fields in dentistry; (2) improving mechanical properties of calcium phosphate; (3) biomimetic process and functionally graded materials. This paper deals with most common types of the calcium phosphate materials such as hydroxyapatite and tricalcium phosphate which are currently used in dental and medical fields. PMID:23878541

Research of footwear lining materials thermoconductive properties

NASA Astrophysics Data System (ADS)

Maksudova, U.; Ilkhamova, M.; Mirzayev, N.; Pazilova, D.

2017-11-01

Protective properties of footwear are influenced by a number of factors and the most important of them are: design features of the top and the bottom of the footwear, it’s shape, physical and mechanical properties of the components of which they are made. In course of work there were researched thermoconductive properties of different lining membrane materials used for production of high temperature protective footwear. Research results allow to select the appropriate materials by reference to thermoconductive properties during design of protective footwear for extreme conditions to prolong the wearer’s time of comfortable stay in conditions of exposure of elevated temperatures to a stack.

A composite material based on recycled tires

NASA Astrophysics Data System (ADS)

Malers, L.; Plesuma, R.; Locmele, L.

2009-01-01

The present study is devoted to the elaboration and investigation of a composite material based on mechanically grinded recycled tires and a polymer binder. The correlation between the content of the binder, some technological parameters, and material properties of the composite was clarified. The apparent density, the compressive stress at a 10% strain, the compressive elastic modulus in static and cyclic loadings, and the insulating properties (acoustic and thermal) were the parameters of special interest of the present investigation. It is found that a purposeful variation of material composition and some technological parameters leads to multifunctional composite materials with different and predictable mechanical and insulation properties.

Morphology and microstructure of composite materials

NASA Technical Reports Server (NTRS)

Tiwari, S. N.; Srinivansan, K.

1991-01-01

Lightweight continuous carbon fiber based polymeric composites are currently enjoying increasing acceptance as structural materials capable of replacing metals and alloys in load bearing applications. As with most new materials, these composites are undergoing trials with several competing processing techniques aimed at cost effectively producing void free consolidations with good mechanical properties. As metallic materials have been in use for several centuries, a considerable database exists on their morphology - microstructure; and the interrelationships between structure and properties have been well documented. Numerous studies on composites have established the crucial relationship between microstructure - morphology and properties. The various microstructural and morphological features of composite materials, particularly those accompanying different processing routes, are documented.

Duplication and concerted evolution of MiSp-encoding genes underlie the material properties of minor ampullate silks of cobweb weaving spiders.

PubMed

Vienneau-Hathaway, Jannelle M; Brassfield, Elizabeth R; Lane, Amanda Kelly; Collin, Matthew A; Correa-Garhwal, Sandra M; Clarke, Thomas H; Schwager, Evelyn E; Garb, Jessica E; Hayashi, Cheryl Y; Ayoub, Nadia A

2017-03-14

Orb-web weaving spiders and their relatives use multiple types of task-specific silks. The majority of spider silk studies have focused on the ultra-tough dragline silk synthesized in major ampullate glands, but other silk types have impressive material properties. For instance, minor ampullate silks of orb-web weaving spiders are as tough as draglines, due to their higher extensibility despite lower strength. Differences in material properties between silk types result from differences in their component proteins, particularly members of the spidroin (spider fibroin) gene family. However, the extent to which variation in material properties within a single silk type can be explained by variation in spidroin sequences is unknown. Here, we compare the minor ampullate spidroins (MiSp) of orb-weavers and cobweb weavers. Orb-web weavers use minor ampullate silk to form the auxiliary spiral of the orb-web while cobweb weavers use it to wrap prey, suggesting that selection pressures on minor ampullate spidroins (MiSp) may differ between the two groups. We report complete or nearly complete MiSp sequences from five cobweb weaving spider species and measure material properties of minor ampullate silks in a subset of these species. We also compare MiSp sequences and silk properties of our cobweb weavers to published data for orb-web weavers. We demonstrate that all our cobweb weavers possess multiple MiSp loci and that one locus is more highly expressed in at least two species. We also find that the proportion of β-spiral-forming amino acid motifs in MiSp positively correlates with minor ampullate silk extensibility across orb-web and cobweb weavers. MiSp sequences vary dramatically within and among spider species, and have likely been subject to multiple rounds of gene duplication and concerted evolution, which have contributed to the diverse material properties of minor ampullate silks. Our sequences also provide templates for recombinant silk proteins with tailored properties.

Computational Screening of 2D Materials for Photocatalysis.

PubMed

Singh, Arunima K; Mathew, Kiran; Zhuang, Houlong L; Hennig, Richard G

2015-03-19

Two-dimensional (2D) materials exhibit a range of extraordinary electronic, optical, and mechanical properties different from their bulk counterparts with potential applications for 2D materials emerging in energy storage and conversion technologies. In this Perspective, we summarize the recent developments in the field of solar water splitting using 2D materials and review a computational screening approach to rapidly and efficiently discover more 2D materials that possess properties suitable for solar water splitting. Computational tools based on density-functional theory can predict the intrinsic properties of potential photocatalyst such as their electronic properties, optical absorbance, and solubility in aqueous solutions. Computational tools enable the exploration of possible routes to enhance the photocatalytic activity of 2D materials by use of mechanical strain, bias potential, doping, and pH. We discuss future research directions and needed method developments for the computational design and optimization of 2D materials for photocatalysis.

Microfabrication of hierarchical structures for engineered mechanical materials

NASA Astrophysics Data System (ADS)

Vera Canudas, Marc

Materials found in nature present, in some cases, unique properties from their constituents that are of great interest in engineered materials for applications ranging from structural materials for the construction of bridges, canals and buildings to the fabrication of new lightweight composites for airplane and automotive bodies, to protective thin film coatings, amongst other fields. Research in the growing field of biomimetic materials indicates that the micro-architectures present in natural materials are critical to their macroscopic mechanical properties. A better understanding of the effect that structure and hierarchy across scales have on the material properties will enable engineered materials with enhanced properties. At the moment, very few theoretical models predict mechanical properties of simple materials based on their microstructures. Moreover these models are based on observations from complex biological systems. One way to overcome this challenge is through the use of microfabrication techniques to design and fabricate simple materials, more appropriate for the study of hierarchical organizations and microstructured materials. Arrays of structures with controlled geometry and dimension can be designed and fabricated at different length scales, ranging from a few hundred nanometers to centimeters, in order to mimic similar systems found in nature. In this thesis, materials have been fabricated in order to gain fundamental insight into the complex hierarchical materials found in nature and to engineer novel materials with enhanced mechanical properties. The materials fabricated here were mechanically characterized and compared to simple mechanics models to describe their behavior with the goal of applying the knowledge acquired to the design and synthesis of future engineered materials with novel properties.

Molecular dynamic simulation for nanometric cutting of single-crystal face-centered cubic metals.

PubMed

Huang, Yanhua; Zong, Wenjun

2014-01-01

In this work, molecular dynamics simulations are performed to investigate the influence of material properties on the nanometric cutting of single crystal copper and aluminum with a diamond cutting tool. The atomic interactions in the two metallic materials are modeled by two sets of embedded atom method (EAM) potential parameters. Simulation results show that although the plastic deformation of the two materials is achieved by dislocation activities, the deformation behavior and related physical phenomena, such as the machining forces, machined surface quality, and chip morphology, are significantly different for different materials. Furthermore, the influence of material properties on the nanometric cutting has a strong dependence on the operating temperature.

The effect of hot isostatic pressing parameters on microstructure and mechanical properties of Eurofer powder HIPed material

NASA Astrophysics Data System (ADS)

Gentzbittel, J. M.; Chu, I.; Burlet, H.

2002-12-01

The production of reduced activation ferritic/martensitic (RAFM) steel by powder metallurgy and high isostatic pressing (HIP) offers numerous advantages for different nuclear applications. The objective of this work is to optimise the Eurofer powder HIP process in order to obtain RAFM solid HIPed steel with similar mechanical properties to those of a forged material. Starting from the forged solid Eurofer steel batch, the material is atomized and the Eurofer powder is characterized in terms of granulometry, chemical composition, surface oxides, etc. Different compaction HIP cycle parameters in the temperature range (950-1100 °C) are tested. The chemical composition of the HIPed material is comparable to the initial forged Eurofer. All the obtained materials are fully dense and the microstructure of the compacted material is well martensitic. The prior austenite grain size seems to be constant in this temperature range. The mechanical tests performed at room temperature reveal acceptable hardness, tensile and Charpy impact properties regarding the ITER specification.

Carbon-Based Nanomaterials: Multi-Functional Materials for Biomedical Engineering

PubMed Central

Cha, Chaenyung; Shin, Su Ryon; Annabi, Nasim; Dokmeci, Mehmet R.; Khademhosseini, Ali

2013-01-01

Functional carbon-based nanomaterials (CBNs) have become important due to their unique combinations of chemical and physical properties (i.e., thermal and electrical conductivity, high mechanical strength, and optical properties), extensive research efforts are being made to utilize these materials for various industrial applications, such as high-strength materials and electronics. These advantageous properties of CBNs are also actively investigated in several areas of biomedical engineering. This Perspective highlights different types of carbon-based nanomaterials currently used in biomedical applications. PMID:23560817

Carbon-based nanomaterials: multifunctional materials for biomedical engineering.

PubMed

Cha, Chaenyung; Shin, Su Ryon; Annabi, Nasim; Dokmeci, Mehmet R; Khademhosseini, Ali

2013-04-23

Functional carbon-based nanomaterials (CBNs) have become important due to their unique combinations of chemical and physical properties (i.e., thermal and electrical conductivity, high mechanical strength, and optical properties), and extensive research efforts are being made to utilize these materials for various industrial applications, such as high-strength materials and electronics. These advantageous properties of CBNs are also actively investigated in several areas of biomedical engineering. This Perspective highlights different types of carbon-based nanomaterials currently used in biomedical applications.

Effective media properties of hyperuniform disordered composite materials

PubMed Central

Sheng, Xin-Qing

2017-01-01

The design challenge of new functional composite materials consisting of multiphase materials has attracted an increasing interest in recent years. In particular, understanding the role of distributions of ordered and disordered particles in a host media is scientifically and technologically important for designing novel materials and devices with superior spectral and angular properties. In this work, the effective medium property of disordered composite materials consisting of hyperuniformly distributed hard particles at different filling fractions is investigated. To accurately extract effective permittivity of a disordered composite material, a full-wave finite element method and the transmission line theory are used. Numerical results show that the theory of hyperuniformity can be conveniently used to design disordered composite materials with good accuracy compared with those materials with randomly dispersed particles. Furthermore, we demonstrate that a Luneburg lens based on the proposed hyperuniform media has superior radiation properties in comparison with previously reported metamaterial designs and it may open up a new avenue in electromagnetic materials-by-design. PMID:28982118

Perspectives of flax processing wastes in building materials production

NASA Astrophysics Data System (ADS)

Smirnova, Olga

2017-01-01

The paper discusses the possibility of using the flax boons for thermal insulation materials. The solution for systematization of materials based on flax boon is suggested. It based on the principle of building materials production using the flax waste with different types of binders. The purpose of the research is to obtain heat-insulating materials with different structure based on agricultural production waste - flax boon, mineral and organic binders. The composition and properties of organic filler - flax boons - are defined using infrared spectroscopy and standard techniques. Using the method of multivariate analysis the optimal ratio of flax boons and binders in production of pressed, porous and granular materials are determined. The effect of particles size distribution of flax boons on the strength of samples with the different composition is studied. As a result, the optimized compositions of pressed, porous and granular materials based on flax boons are obtained. Data on the physical and mechanical properties of these materials are given in the paper.

Chemical properties and colors of fermenting materials in salmon fish sauce production.

PubMed

Nakano, Mitsutoshi; Sagane, Yoshimasa; Koizumi, Ryosuke; Nakazawa, Yozo; Yamazaki, Masao; Watanabe, Toshihiro; Takano, Katsumi; Sato, Hiroaki

2018-02-01

This data article reports the chemical properties (moisture, pH, salinity, and soluble solid content) and colors of fermenting materials in salmon fish sauce products. The fish sauce was produced by mixing salt with differing proportions of raw salmon materials and fermenting for three months; the salmon materials comprised flesh, viscera, an inedible portion, and soft roe. Chemical properties and colors of the unrefined fish sauce ( moromi ), and the refined fish sauce, were analyzed at one, two, and three months following the start of fermentation. Data determined for all products are provided in table format.

Metal-Ceramic composites via “in situ” methods

NASA Astrophysics Data System (ADS)

Florea, R. M.

2017-08-01

Several “in situ” methods for obtaining composite materials with ceramic particles were developed in order to overcome some of the inherent problems associated with conventional processes. This paper reviews the obtaining processes of composite materials with a greater emphasis on nitriding and oxidation by directed melting. These obtaining methods provide microstructures with different combinations of metal-ceramic. Metal matrix composites with controlled amounts of dispersed ceramic particles are obtained by “in situ” processes. The composite materials obtained are having different properties by controlling various processing variables such as temperature, time, the reactant phases and the reinforcing material. The properties of the “in situ” obtained materials depend mainly on the matrix and volume fraction of constituent phase. Briefly are reviewed the mechanical properties, hardness mechanisms and possible applications of these composite materials. Nitridation is much more attractive because with the variation of process parameters is obtained a wider range of microstructures and properties. The activation energy for the formation of AlN (A1N ˜ 100 kJ/mole) is smaller than that of oxidation (Al2O3 ˜ 400 kJ/mole) and growth rates (3 × 10-2 gm/cm2/s) are at least three times higher for oxidation.

Electrical and Thermal Transport Property Studies of High-Temperature Thermoelectric Materials.

DTIC Science & Technology

1984-12-15

Transport Property Studies of High-Temperature Thermoelectric Mateial 12. PERSONAL AUTHIOR(S) 113. TYPE OF REPORT 13b. TIME COVERED Ai DATE OF REPORtT (Yr...with an ABO(3 perovskite structure. Transport properties have been determined for various doping ele- ments and for different compositions. These data...THERMAL TRANSPORT PROPERTY STUDIES Unannounced [j OF HIGH-TEMPERATURE THERMOELECTRIC MATERIALS Justi±icI iou. CONTRACT F-49620-83-0109 DEF By-- Battelle

Analysis of speckle and material properties in laider tracer

NASA Astrophysics Data System (ADS)

Ross, Jacob W.; Rigling, Brian D.; Watson, Edward A.

2017-04-01

The SAL simulation tool Laider Tracer models speckle: the random variation in intensity of an incident light beam across a rough surface. Within Laider Tracer, the speckle field is modeled as a 2-D array of jointly Gaussian random variables projected via ray tracing onto the scene of interest. Originally, all materials in Laider Tracer were treated as ideal diffuse scatterers, for which the far-field return computed uses the Lambertian Bidirectional Reflectance Distribution Function (BRDF). As presented here, we implement material properties into Laider Tracer via the Non-conventional Exploitation Factors Data System: a database of properties for thousands of different materials sampled at various wavelengths and incident angles. We verify the intensity behavior as a function of incident angle after material properties are added to the simulation.

Mechanical properties of experimental composites with different calcium phosphates fillers.

PubMed

Okulus, Zuzanna; Voelkel, Adam

2017-09-01

Calcium phosphates (CaPs)-containing composites have already shown good properties from the point of view of dental restorative materials. The purpose of this study was to examine the crucial mechanical properties of twelve hydroxyapatite- or tricalcium phosphate-filled composites. The raw and surface-treated forms of both CaP fillers were applied. As a reference materials two experimental glass-containing composites and one commercial dental restorative composite were applied. Nano-hardness, elastic modulus, compressive, flexural and diametral tensile strength of all studied materials were determined. Application of statistical methods (one-way analysis of variance and cluster agglomerative analysis) allowed for assessing the similarities between examined materials according to the values of studied parameters. The obtained results show that in almost all cases the mechanical properties of experimental CaPs-composites are comparable or even better than mechanical properties of examined reference materials. Copyright © 2017 Elsevier B.V. All rights reserved.

Crystal Graph Convolutional Neural Networks for an Accurate and Interpretable Prediction of Material Properties

NASA Astrophysics Data System (ADS)

Xie, Tian; Grossman, Jeffrey C.

2018-04-01

The use of machine learning methods for accelerating the design of crystalline materials usually requires manually constructed feature vectors or complex transformation of atom coordinates to input the crystal structure, which either constrains the model to certain crystal types or makes it difficult to provide chemical insights. Here, we develop a crystal graph convolutional neural networks framework to directly learn material properties from the connection of atoms in the crystal, providing a universal and interpretable representation of crystalline materials. Our method provides a highly accurate prediction of density functional theory calculated properties for eight different properties of crystals with various structure types and compositions after being trained with 1 04 data points. Further, our framework is interpretable because one can extract the contributions from local chemical environments to global properties. Using an example of perovskites, we show how this information can be utilized to discover empirical rules for materials design.

Electromagnetic non-destructive technique for duplex stainless steel characterization

NASA Astrophysics Data System (ADS)

Rocha, João Vicente; Camerini, Cesar; Pereira, Gabriela

2016-02-01

Duplex stainless steel (DSS) is a two-phase (ferrite and austenite) material, which exhibits an attractive combination of mechanical properties and high corrosion resistance, being commonly employed for equipment of petrochemical plants, refining units and oil & gas platforms. The best properties of DSS are achieved when the phases are in equal proportions. However, exposition to high temperatures (e.g. welding process) may entail undesired consequences, such as deleterious phases precipitation (e.g. sigma, chi) and different proportion of the original phases, impairing dramatically the mechanical and corrosion properties of the material. A detailed study of the magnetic behavior of DSS microstructure with different ferrite austenite ratios and deleterious phases content was accomplished. The non destructive method evaluates the electromagnetic properties changes in the material and is capable to identify the presence of deleterious phases into DSS microstructure.

Structure and functionality of nanostructured triacylglycerol crystal networks.

PubMed

Ramel, Pere R; Co, Edmund D; Acevedo, Nuria C; Marangoni, Alejandro G

2016-10-01

In this review, recent advances in the characterization of the nanoscale structure of fat crystal networks are outlined. The effect of different factors on the properties of crystalline nanoplatelets (CNPs) is comprehensively described. These are discussed together with the observed changes in polymorphism and micro- or mesostructural properties so as to have a complete understanding of the influence of different internal and external factors on the material properties of fats. The relationship between the nanostructure and the material properties of fats (i.e., oil binding capacity and rheology) is also described. Characterization of the nanostructure of fats has provided a new dimension to the analysis of fat crystal networks and opportunities for nanoengineering that could result in innovations in the food industry with regards to processing and structuring fatty materials. Copyright © 2016 Elsevier B.V. All rights reserved.

Competing covalent and ionic bonding in Ge-Sb-Te phase change materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Subedi, Alaska; Siegrist, Theo; Singh, David J.

Ge 2Sb 2Te 5 and related phase change materials are highly unusual in that they can be readily transformed between amorphous and crystalline states using very fast melt, quench, anneal cycles, although the resulting states are extremely long lived at ambient temperature. These states have remarkably different physical properties including very different optical constants in the visible in strong contrast to common glass formers such as silicates or phosphates. This behavior has been described in terms of resonant bonding, but puzzles remain, particularly regarding different physical properties of crystalline and amorphous phases. Here we show that there is a strongmore » competition between ionic and covalent bonding in cubic phase providing a link between the chemical basis of phase change memory property and origins of giant responses of piezoelectric materials (PbTiO 3, BiFeO 3). This has important consequences for dynamical behavior in particular leading to a simultaneous hardening of acoustic modes and softening of high frequency optic modes in crystalline phase relative to amorphous. As a result, this different bonding in amorphous and crystalline phases provides a direct explanation for different physical properties and understanding of the combination of long time stability and rapid switching and may be useful in finding new phase change compositions with superior properties.« less

Competing covalent and ionic bonding in Ge-Sb-Te phase change materials

DOE PAGES

Subedi, Alaska; Siegrist, Theo; Singh, David J.; ...

2016-05-19

Ge 2Sb 2Te 5 and related phase change materials are highly unusual in that they can be readily transformed between amorphous and crystalline states using very fast melt, quench, anneal cycles, although the resulting states are extremely long lived at ambient temperature. These states have remarkably different physical properties including very different optical constants in the visible in strong contrast to common glass formers such as silicates or phosphates. This behavior has been described in terms of resonant bonding, but puzzles remain, particularly regarding different physical properties of crystalline and amorphous phases. Here we show that there is a strongmore » competition between ionic and covalent bonding in cubic phase providing a link between the chemical basis of phase change memory property and origins of giant responses of piezoelectric materials (PbTiO 3, BiFeO 3). This has important consequences for dynamical behavior in particular leading to a simultaneous hardening of acoustic modes and softening of high frequency optic modes in crystalline phase relative to amorphous. As a result, this different bonding in amorphous and crystalline phases provides a direct explanation for different physical properties and understanding of the combination of long time stability and rapid switching and may be useful in finding new phase change compositions with superior properties.« less

Competing covalent and ionic bonding in Ge-Sb-Te phase change materials.

PubMed

Mukhopadhyay, Saikat; Sun, Jifeng; Subedi, Alaska; Siegrist, Theo; Singh, David J

2016-05-19

Ge2Sb2Te5 and related phase change materials are highly unusual in that they can be readily transformed between amorphous and crystalline states using very fast melt, quench, anneal cycles, although the resulting states are extremely long lived at ambient temperature. These states have remarkably different physical properties including very different optical constants in the visible in strong contrast to common glass formers such as silicates or phosphates. This behavior has been described in terms of resonant bonding, but puzzles remain, particularly regarding different physical properties of crystalline and amorphous phases. Here we show that there is a strong competition between ionic and covalent bonding in cubic phase providing a link between the chemical basis of phase change memory property and origins of giant responses of piezoelectric materials (PbTiO3, BiFeO3). This has important consequences for dynamical behavior in particular leading to a simultaneous hardening of acoustic modes and softening of high frequency optic modes in crystalline phase relative to amorphous. This different bonding in amorphous and crystalline phases provides a direct explanation for different physical properties and understanding of the combination of long time stability and rapid switching and may be useful in finding new phase change compositions with superior properties.

Effect of geometric configuration on the electrocaloric properties of nanoscale ferroelectric materials

NASA Astrophysics Data System (ADS)

Hou, Xu; Li, Huiyu; Shimada, Takahiro; Kitamura, Takayuki; Wang, Jie

2018-03-01

The electrocaloric properties of ferroelectrics are highly dependent on the domain structure in the materials. For nanoscale ferroelectric materials, the domain structure is greatly influenced by the geometric configuration of the system. Using a real-space phase field model based on the Ginzburg-Landau theory, we investigate the effect of geometric configurations on the electrocaloric properties of nanoscale ferroelectric materials. The ferroelectric hysteresis loops under different temperatures are simulated for the ferroelectric nano-metamaterials with square, honeycomb, and triangular Archimedean geometric configurations. The adiabatic temperature changes (ATCs) for three ferroelectric nano-metamaterials under different electric fields are calculated from the Maxwell relationship based on the hysteresis loops. It is found that the honeycomb specimen exhibits the largest ATC of Δ T = 4.3 °C under a field of 391.8 kV/cm among three geometric configurations, whereas the square specimen has the smallest ATC of Δ T = 2.7 °C under the same electric field. The different electrocaloric properties for three geometric configurations stem from the different domain structures. There are more free surfaces perpendicular to the electric field in the square specimen than the other two specimens, which restrict more polarizations perpendicular to the electric field, resulting in a small ATC. Due to the absence of free surfaces perpendicular to the electric field in the honeycomb specimen, the change of polarization with temperature in the direction of the electric field is more easy and thus leads to a large ATC. The present work suggests a novel approach to obtain the tunable electrocaloric properties in nanoscale ferroelectric materials by designing their geometric configurations.

Optical properties (bidirectional reflectance distribution function) of shot fabric.

PubMed

Lu, R; Koenderink, J J; Kappers, A M

2000-11-01

To study the optical properties of materials, one needs a complete set of the angular distribution functions of surface scattering from the materials. Here we present a convenient method for collecting a large set of bidirectional reflectance distribution function (BRDF) samples in the hemispherical scattering space. Material samples are wrapped around a right-circular cylinder and irradiated by a parallel light source, and the scattered radiance is collected by a digital camera. We tilted the cylinder around its center to collect the BRDF samples outside the plane of incidence. This method can be used with materials that have isotropic and anisotropic scattering properties. We demonstrate this method in a detailed investigation of shot fabrics. The warps and the fillings of shot fabrics are dyed different colors so that the fabric appears to change color at different viewing angles. These color-changing characteristics are found to be related to the physical and geometrical structure of shot fabric. Our study reveals that the color-changing property of shot fabrics is due mainly to an occlusion effect.

Physicochemical of pillared clays prepared by several metal oxides

NASA Astrophysics Data System (ADS)

Rinaldi, Nino; Kristiani, Anis

2017-03-01

Natural clays could be modified by the pillarization method, called as Pillared Clays (PILCs). PILCs have been known as porous materials that can be used for many applications, one of the fields is catalysis. PILCs as two dimensional materials are interesting because their structures and textural properties can be controlled by using a metal oxide as the pillar. Different metal oxide used as the pillar causes different properties results of pillared clays. Usually, natural smectite clays/bentonites are used as a raw material. Therefore, a series of bentonite pillared by metal oxides was prepared through pillarization method. Variation of metals pillared into bentonite are aluminium, chromium, zirconium, and ferro. The physicochemical properties of catalysts were characterized by using X-ray Diffraction (XRD), Thermo Gravimetric Analysis (TGA), Brunauer-Emmett-Teller (BET) and Barret-Joyner-Halenda (BJH) analysis, and Fourier transform infrared spectroscopy (FTIR) measurement. Noteworthy characterization results showed that different metals pillared into bentonite affected physical and chemical properties, i.e. basal spacing, surface area, pore size distribution, thermal stability and acidity.

Effect of Injection Molding Melt Temperatures on PLGA Craniofacial Plate Properties during In Vitro Degradation

PubMed Central

Fancello, Eduardo Alberto

2017-01-01

The purpose of this article is to present mechanical and physicochemical properties during in vitro degradation of PLGA material as craniofacial plates based on different values of injection molded temperatures. Injection molded plates were submitted to in vitro degradation in a thermostat bath at 37 ± 1°C by 16 weeks. The material was removed after 15, 30, 60, and 120 days; then bending stiffness, crystallinity, molecular weights, and viscoelasticity were studied. A significant decrease of molecular weight and mechanical properties over time and a difference in FT-IR after 60 days showed faster degradation of the material in the geometry studied. DSC analysis confirmed that the crystallization occurred, especially in higher melt temperature condition. DMA analysis suggests a greater contribution of the viscous component of higher temperature than lower temperature in thermomechanical behavior. The results suggest that physical-mechanical properties of PLGA plates among degradation differ per injection molding temperatures. PMID:29056968

On the Use of Biaxial Properties in Modeling Annulus as a Holzapfel–Gasser–Ogden Material

PubMed Central

Momeni Shahraki, Narjes; Fatemi, Ali; Goel, Vijay K.; Agarwal, Anand

2015-01-01

Besides the biology, stresses and strains within the tissue greatly influence the location of damage initiation and mode of failure in an intervertebral disk. Finite element models of a functional spinal unit (FSU) that incorporate reasonably accurate geometry and appropriate material properties are suitable to investigate such issues. Different material models and techniques have been used to model the anisotropic annulus fibrosus, but the abilities of these models to predict damage initiation in the annulus and to explain clinically observed phenomena are unclear. In this study, a hyperelastic anisotropic material model for the annulus with two different sets of material constants, experimentally determined using uniaxial and biaxial loading conditions, were incorporated in a 3D finite element model of a ligamentous FSU. The purpose of the study was to highlight the biomechanical differences (e.g., intradiscal pressure, motion, forces, stresses, strains, etc.) due to the dissimilarity between the two sets of material properties (uniaxial and biaxial). Based on the analyses, the biaxial constants simulations resulted in better agreements with the in vitro and in vivo data, and thus are more suitable for future damage analysis and failure prediction of the annulus under complex multiaxial loading conditions. PMID:26090359

Effect of ionizing radiation on physicochemical and mechanical properties of commercial multilayer coextruded flexible plastics packaging materials

NASA Astrophysics Data System (ADS)

Goulas, Antonios E.; Riganakos, Kyriakos A.; Kontominas, Michael G.

2003-12-01

The effect of gamma radiation (doses: 5, 10 and 30 kGy) on mechanical properties, gas and water vapour permeability and overall migration values into distilled water, 3% aqueous acetic acid and iso-octane was studied for a series of commercial multilayer flexible packaging materials based on coextruded polypropylene (PP), ethylene vinyl alcohol (EVOH), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polyamide (PA) and Ionomer. The results showed that radiation doses of 5 and 10 kGy induced no statistically significant differences ( p>0.05) in all polymer properties examined. A dose of 30 kGy induced differences ( p<0.05) in the mechanical properties of PA/LDPE, LDPE/EVOH/LDPE and LDPE/PA/Ionomer films. In addition, the same dose induced differences ( p<0.05) in the overall migration from Ionomer/EVOH/LDPE and LDPE/PA/Ionomer films into 3% acetic acid and iso-octane and in the overall migration from PP/EVOH/LDPE-LLDPE into iso-octane. Differences recorded, are discussed in relation to food irradiation applications of respective packaging materials.

Pin Tool Geometry Effects in Friction Stir Welding

NASA Technical Reports Server (NTRS)

Querin, J. A.; Rubisoff, H. A.; Schneider, J. A.

2009-01-01

In friction stir welding (FSW) there is significant evidence that material can take one of two different flow paths when being displaced from its original position in front of the pin tool to its final position in the wake of the weld. The geometry of the pin tool, along with the process parameters, plays an important role in dictating the path that the material takes. Each flow path will impart a different thermomechanical history on the material, consequently altering the material microstructure and subsequent weld properties. The intention of this research is to isolate the effect that different pin tool attributes have on the flow paths imparted on the FSWed material. Based on published weld tool geometries, a variety of weld tools were fabricated and used to join AA2219. Results from the tensile properties and microstructural characterization will be presented.

Determination of orthotropic mechanical properties of 3D printed parts for structural health monitoring

NASA Astrophysics Data System (ADS)

Poissenot-Arrigoni, Bastien; Scheyer, Austin; Anton, Steven R.

2017-04-01

The evolution of additive manufacturing has allowed engineers to use 3D printing for many purposes. As a natural consequence of the 3D printing process, the printed object is anisotropic. As part of an ongoing project to embed piezoelectric devices in 3D printed structures for structural health monitoring (SHM), this study aims to find the mechanical properties of the 3D printed material and the influence of different external factors on those properties. The orthotropic mechanical properties of a 3D printed structure are dependent on the printing parameters used to create the structure. In order to develop an orthotropic material model, mechanical properties will be found experimentally from additively manufactured samples created from polylactic acid (PLA) using a consumer-level fused deposition modeling (FDM) printer; the Lulzbot TAZ 6. Nine mechanical constants including three Young's moduli, three Poisson's ratios, and three shear moduli are needed to fully describe the 3D elastic behavior of the material. Printed specimens with different raster orientations and print orientations allow calculation of the different material constants. In this work, seven of the nine mechanical constants were found. Two shear moduli were unable to be measured due to difficulties in printing two of the sample orientations. These mechanical properties are needed in order to develop orthotropic material models of systems employing 3D printed PLA. The results from this paper will be used to create a model of a piezoelectric transducer embedded in a 3D printed structure for structural health monitoring.

Phonon properties of iron-based superconductors

NASA Astrophysics Data System (ADS)

Gupta, Yuhit; Goyal, Megha; Sinha, M. M.

2018-05-01

Earlier, it was thought there is antagonist relationship between superconductivity and ferromagnetic materials, But, a discovery of iron-based superconductors have removed this misconception. It gives an idea to make a review on the superconductivity properties of different materials. The new iron-based superconductors' present symmetry breaking competing phases in the form of tetragonal to orthorhombic transition. It consists of mainly four families [1111], [111], [122], and [11] type. Superconductivity of iron-based superconductors mainly related with the phonons and there is an excellent relation between phonons and superconductivity. Phonons properties are helpful in predicting the superconducting properties of materials. Phonon properties of iron-based superconductors in various phases are summarized in this study. We are presenting the review of phonon properties of iron-based superconductors.

Tuning Material Properties of Oxides and Nitrides by Substrate Biasing during Plasma-Enhanced Atomic Layer Deposition on Planar and 3D Substrate Topographies

PubMed Central

2018-01-01

Oxide and nitride thin-films of Ti, Hf, and Si serve numerous applications owing to the diverse range of their material properties. It is therefore imperative to have proper control over these properties during materials processing. Ion-surface interactions during plasma processing techniques can influence the properties of a growing film. In this work, we investigated the effects of controlling ion characteristics (energy, dose) on the properties of the aforementioned materials during plasma-enhanced atomic layer deposition (PEALD) on planar and 3D substrate topographies. We used a 200 mm remote PEALD system equipped with substrate biasing to control the energy and dose of ions by varying the magnitude and duration of the applied bias, respectively, during plasma exposure. Implementing substrate biasing in these forms enhanced PEALD process capability by providing two additional parameters for tuning a wide range of material properties. Below the regimes of ion-induced degradation, enhancing ion energies with substrate biasing during PEALD increased the refractive index and mass density of TiOx and HfOx and enabled control over their crystalline properties. PEALD of these oxides with substrate biasing at 150 °C led to the formation of crystalline material at the low temperature, which would otherwise yield amorphous films for deposition without biasing. Enhanced ion energies drastically reduced the resistivity of conductive TiNx and HfNx films. Furthermore, biasing during PEALD enabled the residual stress of these materials to be altered from tensile to compressive. The properties of SiOx were slightly improved whereas those of SiNx were degraded as a function of substrate biasing. PEALD on 3D trench nanostructures with biasing induced differing film properties at different regions of the 3D substrate. On the basis of the results presented herein, prospects afforded by the implementation of this technique during PEALD, such as enabling new routes for topographically selective deposition on 3D substrates, are discussed. PMID:29554799

The Use of Empirical Methods for Testing Granular Materials in Analogue Modelling

PubMed Central

Montanari, Domenico; Agostini, Andrea; Bonini, Marco; Corti, Giacomo; Del Ventisette, Chiara

2017-01-01

The behaviour of a granular material is mainly dependent on its frictional properties, angle of internal friction, and cohesion, which, together with material density, are the key factors to be considered during the scaling procedure of analogue models. The frictional properties of a granular material are usually investigated by means of technical instruments such as a Hubbert-type apparatus and ring shear testers, which allow for investigating the response of the tested material to a wide range of applied stresses. Here we explore the possibility to determine material properties by means of different empirical methods applied to mixtures of quartz and K-feldspar sand. Empirical methods exhibit the great advantage of measuring the properties of a certain analogue material under the experimental conditions, which are strongly sensitive to the handling techniques. Finally, the results obtained from the empirical methods have been compared with ring shear tests carried out on the same materials, which show a satisfactory agreement with those determined empirically. PMID:28772993

A three-dimensional inverse finite element analysis of the heel pad.

PubMed

Chokhandre, Snehal; Halloran, Jason P; van den Bogert, Antonie J; Erdemir, Ahmet

2012-03-01

Quantification of plantar tissue behavior of the heel pad is essential in developing computational models for predictive analysis of preventive treatment options such as footwear for patients with diabetes. Simulation based studies in the past have generally adopted heel pad properties from the literature, in return using heel-specific geometry with material properties of a different heel. In exceptional cases, patient-specific material characterization was performed with simplified two-dimensional models, without further evaluation of a heel-specific response under different loading conditions. The aim of this study was to conduct an inverse finite element analysis of the heel in order to calculate heel-specific material properties in situ. Multidimensional experimental data available from a previous cadaver study by Erdemir et al. ("An Elaborate Data Set Characterizing the Mechanical Response of the Foot," ASME J. Biomech. Eng., 131(9), pp. 094502) was used for model development, optimization, and evaluation of material properties. A specimen-specific three-dimensional finite element representation was developed. Heel pad material properties were determined using inverse finite element analysis by fitting the model behavior to the experimental data. Compression dominant loading, applied using a spherical indenter, was used for optimization of the material properties. The optimized material properties were evaluated through simulations representative of a combined loading scenario (compression and anterior-posterior shear) with a spherical indenter and also of a compression dominant loading applied using an elevated platform. Optimized heel pad material coefficients were 0.001084 MPa (μ), 9.780 (α) (with an effective Poisson's ratio (ν) of 0.475), for a first-order nearly incompressible Ogden material model. The model predicted structural response of the heel pad was in good agreement for both the optimization (<1.05% maximum tool force, 0.9% maximum tool displacement) and validation cases (6.5% maximum tool force, 15% maximum tool displacement). The inverse analysis successfully predicted the material properties for the given specimen-specific heel pad using the experimental data for the specimen. The modeling framework and results can be used for accurate predictions of the three-dimensional interaction of the heel pad with its surroundings.

Failure of Non-Circular Composite Cylinders

NASA Technical Reports Server (NTRS)

Hyer, M. W.

2004-01-01

In this study, a progressive failure analysis is used to investigate leakage in internally pressurized non-circular composite cylinders. This type of approach accounts for the localized loss of stiffness when material failure occurs at some location in a structure by degrading the local material elastic properties by a certain factor. The manner in which this degradation of material properties takes place depends on the failure modes, which are determined by the application of a failure criterion. The finite-element code STAGS, which has the capability to perform progressive failure analysis using different degradation schemes and failure criteria, is utilized to analyze laboratory scale, graphite-epoxy, elliptical cylinders with quasi-isotropic, circumferentially-stiff, and axially-stiff material orthotropies. The results are divided into two parts. The first part shows that leakage, which is assumed to develop if there is material failure in every layer at some axial and circumferential location within the cylinder, does not occur without failure of fibers. Moreover before fibers begin to fail, only matrix tensile failures, or matrix cracking, takes place, and at least one layer in all three cylinders studied remain uncracked, preventing the formation of a leakage path. That determination is corroborated by the use of different degradation schemes and various failure criteria. Among the degradation schemes investigated are the degradation of different engineering properties, the use of various degradation factors, the recursive or non-recursive degradation of the engineering properties, and the degradation of material properties using different computational approaches. The failure criteria used in the analysis include the noninteractive maximum stress criterion and the interactive Hashin and Tsai-Wu criteria. The second part of the results shows that leakage occurs due to a combination of matrix tensile and compressive, fiber tensile and compressive, and inplane shear failure modes in all three cylinders. Leakage develops after a relatively low amount of fiber damage, at about the same pressure for three material orthotropies, and at approximately the same location.

Materials by Design—A Perspective From Atoms to Structures

PubMed Central

Buehler, Markus J.

2013-01-01

Biological materials are effectively synthesized, controlled, and used for a variety of purposes—in spite of limitations in energy, quality, and quantity of their building blocks. Whereas the chemical composition of materials in the living world plays a some role in achieving functional properties, the way components are connected at different length scales defines what material properties can be achieved, how they can be altered to meet functional requirements, and how they fail in disease states and other extreme conditions. Recent work has demonstrated this by using large-scale computer simulations to predict materials properties from fundamental molecular principles, combined with experimental work and new mathematical techniques to categorize complex structure-property relationships into a systematic framework. Enabled by such categorization, we discuss opportunities based on the exploitation of concepts from distinct hierarchical systems that share common principles in how function is created, linking music to materials science. PMID:24163499

Effect of curing mode on the micro-mechanical properties of dual-cured self-adhesive resin cements.

PubMed

Ilie, Nicoleta; Simon, Alexander

2012-04-01

Light supplying to luting resin cements is impeded in several clinical situations, causing us to question whether materials can properly be cured to achieve adequately (or adequate) mechanical properties. The aim of this study was therefore to analyse the effect of light on the micro-mechanical properties of eight popular dual-cured self-adhesive resin cements by comparing them with two conventional, also dual-cured, resin cements. Four different curing procedures were applied: auto-polymerisation (dark curing) and light curing (LED unit, Freelight 2, 20 s) by applying the unit directly on the samples' surface, at a distance of 5 and 10 mm. Twenty minutes after curing, the samples were stored for 1 week at 37°C in a water-saturated atmosphere. The micro-mechanical properties-Vickers hardness, modulus of elasticity, creep and elastic/plastic deformation-were measured. Data were analysed with multivariate ANOVA followed by Tukey's test and partial eta-squared statistics (p < 0.05). A very strong influence of the material as well as filler volume and weight on the micro-mechanical properties was measured, whereas the influence of the curing procedure and type of cement-conventional or self-adhesive-was generally low. The influence of light on the polymerisation process was material dependent, with four different behaviour patterns to be distinguished. As a material category, significantly higher micro-mechanical properties were measured for the conventional compared to the self-adhesive resin cements, although this difference was low. Within the self-adhesive resin cements group, the variation in micro-mechanical properties was high. The selection of suitable resin cements should be done by considering, besides its adhesive properties, its micro-mechanical properties and curing behaviour also.

Influence of physical activity on tibial bone material properties in laying hens

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodriguez-Navarro, A. B.; McCormack, H. M.; Fleming, R. H.

Laying hens develop a type of osteoporosis that arises from a loss of structural bone, resulting in high incidence of fractures. In this study, a comparison of bone material properties was made for lines of hens created by divergent selection to have high and low bone strength and housed in either individual cages, with restricted mobility, or in an aviary system, with opportunity for increased mobility. Improvement of bone biomechanics in the high line hens and in aviary housing was mainly due to increased bone mass, thicker cortical bone and more medullary bone. However, bone material properties such as corticalmore » and medullary bone mineral composition and crystallinity as well as collagen maturity did not differ between lines. However, bone material properties of birds from the different type of housing were markedly different. The cortical bone in aviary birds had a lower degree of mineralization and bone mineral was less mature and less organized than in caged birds. Here, these differences can be explained by increased bone turnover rates due to the higher physical activity of aviary birds that stimulates bone formation and bone remodeling. Multivariate statistical analyses shows that both cortical and medullary bone contribute to breaking strengthThe cortical thickness was the single most important contributor while its degree of mineralization and porosity had a smaller contribution. Lastly, bone properties had poorer correlations with mechanical properties in cage birds than in aviary birds presumably due to the greater number of structural defects of cortical bone in cage birds.« less

Influence of physical activity on tibial bone material properties in laying hens

DOE PAGES

Rodriguez-Navarro, A. B.; McCormack, H. M.; Fleming, R. H.; ...

2017-11-03

Laying hens develop a type of osteoporosis that arises from a loss of structural bone, resulting in high incidence of fractures. In this study, a comparison of bone material properties was made for lines of hens created by divergent selection to have high and low bone strength and housed in either individual cages, with restricted mobility, or in an aviary system, with opportunity for increased mobility. Improvement of bone biomechanics in the high line hens and in aviary housing was mainly due to increased bone mass, thicker cortical bone and more medullary bone. However, bone material properties such as corticalmore » and medullary bone mineral composition and crystallinity as well as collagen maturity did not differ between lines. However, bone material properties of birds from the different type of housing were markedly different. The cortical bone in aviary birds had a lower degree of mineralization and bone mineral was less mature and less organized than in caged birds. Here, these differences can be explained by increased bone turnover rates due to the higher physical activity of aviary birds that stimulates bone formation and bone remodeling. Multivariate statistical analyses shows that both cortical and medullary bone contribute to breaking strengthThe cortical thickness was the single most important contributor while its degree of mineralization and porosity had a smaller contribution. Lastly, bone properties had poorer correlations with mechanical properties in cage birds than in aviary birds presumably due to the greater number of structural defects of cortical bone in cage birds.« less

Rheology of tissue conditioners.

PubMed

Murata, H; Hamada, T; Djulaeha, E; Nikawa, H

1998-02-01

Tissue conditioners can be used to condition abused tissues, record functional impressions, make temporary relinings, and for other clinical applications, mainly because of their specific viscoelasticity. However, little information is available on the rheology of the materials, manipulation, and suitability for various clinical applications. This study evaluated the gelation times, the viscoelastic properties after gelation of tissue conditioners, and the influence of the powder/liquid (P/L) ratio. Ten tissue conditioners were used and gelation times were obtained with an oscillating rheometer. A series of stress relaxation tests were also conducted to evaluate the viscoelastic properties after gelation and the changes with the passage of time by means of Maxwell model analogies. Significant differences were found in the gelation times and flow properties after gelation among the materials mixed with the P/L ratios recommended by the manufacturers. The flow properties tended to increase with time of storage. Large differences in the limits of the clinically acceptable P/L ratios and the adjustable limits of elasticity and viscosity by altering P/L ratios were found among the materials. The results suggested that each material should be selected according to each clinical purpose because of the wide ranges of viscoelastic properties and changes in viscoelasticity with time among the materials. Furthermore, gelation times and the viscoelastic properties after gelation can be controlled to improve handling and suit various applications by altering the P/L ratios within the acceptable limits.

Simultaneous Contact Sensing and Characterizing of Mechanical and Dynamic Heat Transfer Properties of Porous Polymeric Materials

PubMed Central

Yao, Bao-Guo; Peng, Yun-Liang; Zhang, De-Pin

2017-01-01

Porous polymeric materials, such as textile fabrics, are elastic and widely used in our daily life for garment and household products. The mechanical and dynamic heat transfer properties of porous polymeric materials, which describe the sensations during the contact process between porous polymeric materials and parts of the human body, such as the hand, primarily influence comfort sensations and aesthetic qualities of clothing. A multi-sensory measurement system and a new method were proposed to simultaneously sense the contact and characterize the mechanical and dynamic heat transfer properties of porous polymeric materials, such as textile fabrics in one instrument, with consideration of the interactions between different aspects of contact feels. The multi-sensory measurement system was developed for simulating the dynamic contact and psychological judgment processes during human hand contact with porous polymeric materials, and measuring the surface smoothness, compression resilience, bending and twisting, and dynamic heat transfer signals simultaneously. The contact sensing principle and the evaluation methods were presented. Twelve typical sample materials with different structural parameters were measured. The results of the experiments and the interpretation of the test results were described. An analysis of the variance and a capacity study were investigated to determine the significance of differences among the test materials and to assess the gage repeatability and reproducibility. A correlation analysis was conducted by comparing the test results of this measurement system with the results of Kawabata Evaluation System (KES) in separate instruments. This multi-sensory measurement system provides a new method for simultaneous contact sensing and characterizing of mechanical and dynamic heat transfer properties of porous polymeric materials. PMID:29084152

Simultaneous Contact Sensing and Characterizing of Mechanical and Dynamic Heat Transfer Properties of Porous Polymeric Materials.

PubMed

Yao, Bao-Guo; Peng, Yun-Liang; Zhang, De-Pin

2017-10-30

Porous polymeric materials, such as textile fabrics, are elastic and widely used in our daily life for garment and household products. The mechanical and dynamic heat transfer properties of porous polymeric materials, which describe the sensations during the contact process between porous polymeric materials and parts of the human body, such as the hand, primarily influence comfort sensations and aesthetic qualities of clothing. A multi-sensory measurement system and a new method were proposed to simultaneously sense the contact and characterize the mechanical and dynamic heat transfer properties of porous polymeric materials, such as textile fabrics in one instrument, with consideration of the interactions between different aspects of contact feels. The multi-sensory measurement system was developed for simulating the dynamic contact and psychological judgment processes during human hand contact with porous polymeric materials, and measuring the surface smoothness, compression resilience, bending and twisting, and dynamic heat transfer signals simultaneously. The contact sensing principle and the evaluation methods were presented. Twelve typical sample materials with different structural parameters were measured. The results of the experiments and the interpretation of the test results were described. An analysis of the variance and a capacity study were investigated to determine the significance of differences among the test materials and to assess the gage repeatability and reproducibility. A correlation analysis was conducted by comparing the test results of this measurement system with the results of Kawabata Evaluation System (KES) in separate instruments. This multi-sensory measurement system provides a new method for simultaneous contact sensing and characterizing of mechanical and dynamic heat transfer properties of porous polymeric materials.

Effects of temperature changes and stress loading on the mechanical and shape memory properties of thermoplastic materials with different glass transition behaviours and crystal structures.

PubMed

Iijima, Masahiro; Kohda, Naohisa; Kawaguchi, Kyotaro; Muguruma, Takeshi; Ohta, Mitsuru; Naganishi, Atsuko; Murakami, Takashi; Mizoguchi, Itaru

2015-12-01

To investigate the effects of temperature changes and stress loading on the mechanical and shape memory properties of thermoplastic materials with different glass transition behaviours and crystal structures. Five thermoplastic materials, polyethylene terephthalate glycol (Duran®, Scheu Dental), polypropylene (Hardcast®, Scheu Dental), and polyurethane (SMP MM®, SMP Technologies) with three different glass transition temperatures (T g) were selected. The T g and crystal structure were assessed using differential scanning calorimetry and X-ray diffraction. The deterioration of mechanical properties by thermal cycling and the orthodontic forces during stepwise temperature changes were investigated using nanoindentation testing and custom-made force-measuring system. The mechanical properties were also evaluated by three-point bending tests; shape recovery with heating was then investigated. The mechanical properties for each material were decreased significantly by 2500 cycles and great decrease was observed for Hardcast (crystal plastic) with higher T g (155.5°C) and PU 1 (crystalline or semi-crystalline plastic) with lower T g (29.6°C). The Duran, PU 2, and PU 3 with intermediate T g (75.3°C for Duran, 56.5°C for PU 2, and 80.7°C for PU 3) showed relatively stable mechanical properties with thermal cycling. The polyurethane polymers showed perfect shape memory effect within the range of intraoral temperature changes. The orthodontic force produced by thermoplastic appliances decreased with the stepwise temperature change for all materials. Orthodontic forces delivered by thermoplastic appliances may influence by the T g of the materials, but not the crystal structure. Polyurethane is attractive thermoplastic materials due to their unique shape memory phenomenon, but stress relaxation with temperature changes is expected. © The Author 2015. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Confined-Volume Effect on the Thermal Properties of Encapsulated Phase Change Materials for Thermal Energy Storage.

PubMed

De Castro, Paula F; Ahmed, Adham; Shchukin, Dmitry G

2016-03-18

We have encapsulated the heat exchange material, n-docosane, into polyurethane capsules of different sizes. Decreasing the size of the capsules leads to changes of the crystallinity of phase-change material as well as melting/crystallization temperature. The novelty of the paper includes 1) protection of the nanostructured energy-enriched materials against environment during storage and controlled release of the encapsulated energy on demand and 2) study of the structure and surface-to-volume properties of the energy-enriched materials dispersed in capsules of different sizes. The stability of energy nanomaterials, influence of capsule diameter on their energy capacity, homogeneity and operation lifetime are investigated. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

VZLUSAT-1: verification of new materials and technologies for space

NASA Astrophysics Data System (ADS)

Daniel, Vladimir; Urban, Martin; Nentvich, Ondrej; Stehlikova, Veronika

2016-09-01

CubeSats are a good opportunity to test new technologies and materials on orbit. These innovations can be later used for improving of properties and life length of Cubesat or other satellites as well. VZLUSAT-1 is a small satellite from the CubeSat family, which will carry a wide scale of payloads with different purposes. The poster is focused on measuring of degradation and properties measurement of new radiation hardened composite material in orbit due to space environment. Material properties changes can be studied by many methods and in many disciplines. One payload measures mechanical changes in dependence on Young's modulus of elasticity which is got from non-destructive testing by mechanical vibrations. The natural frequencies we get using Fast Fourier Transform. The material is tested also by several thermometers which measure heat distribution through the composite, as well as reflectivity in dependence on different coatings. The satellite also will measure the material radiation shielding properties. There are PIN diodes which measure the relative shielding efficiency of composite and how it will change in time in space environment. Last one of material space testing is measurement of outgassing from tested composite material. It could be very dangerous for other parts of satellite, like detectors, when anything was outgassing, for example water steam. There are several humidity sensors which are sensitive to steam and other gases and measures temperatures as well.

Material Perception.

PubMed

Fleming, Roland W

2017-09-15

Under typical viewing conditions, human observers effortlessly recognize materials and infer their physical, functional, and multisensory properties at a glance. Without touching materials, we can usually tell whether they would feel hard or soft, rough or smooth, wet or dry. We have vivid visual intuitions about how deformable materials like liquids or textiles respond to external forces and how surfaces like chrome, wax, or leather change appearance when formed into different shapes or viewed under different lighting. These achievements are impressive because the retinal image results from complex optical interactions between lighting, shape, and material, which cannot easily be disentangled. Here I argue that because of the diversity, mutability, and complexity of materials, they pose enormous challenges to vision science: What is material appearance, and how do we measure it? How are material properties estimated and represented? Resolving these questions causes us to scrutinize the basic assumptions of mid-level vision.

Electrical insulating liquid: A review

NASA Astrophysics Data System (ADS)

Mahanta, Deba Kumar; Laskar, Shakuntala

Insulating liquid plays an important role for the life span of the transformer. Petroleum-based mineral oil has become dominant insulating liquid of transformer for more than a century for its excellent dielectric and cooling properties. However, the usage of petroleum-based mineral oil, derived from a nonrenewable energy source, has affected the environment for its nonbiodegradability property. Therefore, researchers direct their attention to renewable and biodegradable alternatives. Palm fatty acid ester, coconut oil, sunflower oil, etc. are considered as alternatives to replace mineral oil as transformer insulation liquid. This paper gives an extensive review of different liquid insulating materials used in a transformer. Characterization of different liquids as an insulating material has been discussed. An attempt has been made to classify different insulating liquids-based on different properties.

Designing with non-linear viscoelastic fluids

NASA Astrophysics Data System (ADS)

Schuh, Jonathon; Lee, Yong Hoon; Allison, James; Ewoldt, Randy

2017-11-01

Material design is typically limited to hard materials or simple fluids; however, design with more complex materials can provide ways to enhance performance. Using the Criminale-Ericksen-Filbey (CEF) constitutive model in the thin film lubrication limit, we derive a modified Reynolds Equation (based on asymptotic analysis) that includes shear thinning, first normal stress, and terminal regime viscoelastic effects. This allows for designing non-linear viscoelastic fluids in thin-film creeping flow scenarios, i.e. optimizing the shape of rheological material properties to achieve different design objectives. We solve the modified Reynolds equation using the pseudo-spectral method, and describe a case study in full-film lubricated sliding where optimal fluid properties are identified. These material-agnostic property targets can then guide formulation of complex fluids which may use polymeric, colloidal, or other creative approaches to achieve the desired non-Newtonian properties.

Micromechanical measurement of wood substructure properties.

Treesearch

David E. Kretschmann; Troy W. Schmidt; Roderic S. Lakes; Steven M. Cramer

2002-01-01

The annual rings of softwoods are visually obvious and represent cylindrical layers of primarily cellulosic material that possess significantly different properties. For simplicity, wood construction products are designed assuming a material homogeneity that does not exist. As rapidly grown plantation trees are used for wood products, fewer rings are contained in an...

Effects of temperature and material on dielectric properties of pelleted wood-based biomass

USDA-ARS?s Scientific Manuscript database

The production of pelleted biomass represents a significant emerging industry in the United States. Solid biomass can be formed from the waste products of many different products. In this study, the effects of temperature and pellet material type on the dielectric properties were investigated. Tempe...

Anisotropic evaluation of synthetic surgical meshes.

PubMed

Saberski, E R; Orenstein, S B; Novitsky, Y W

2011-02-01

The material properties of meshes used in hernia repair contribute to the overall mechanical behavior of the repair. The anisotropic potential of synthetic meshes, representing a difference in material properties (e.g., elasticity) in different material axes, is not well defined to date. Haphazard orientation of anisotropic mesh material can contribute to inconsistent surgical outcomes. We aimed to characterize and compare anisotropic properties of commonly used synthetic meshes. Six different polypropylene (Trelex(®), ProLite™, Ultrapro™), polyester (Parietex™), and PTFE-based (Dualmesh(®), Infinit) synthetic meshes were selected. Longitudinal and transverse axes were defined for each mesh, and samples were cut in each axis orientation. Samples underwent uniaxial tensile testing, from which the elastic modulus (E) in each axis was determined. The degree of anisotropy (λ) was calculated as a logarithmic expression of the ratio between the elastic modulus in each axis. Five of six meshes displayed significant anisotropic behavior. Ultrapro™ and Infinit exhibited approximately 12- and 20-fold differences between perpendicular axes, respectively. Trelex(®), ProLite™, and Parietex™ were 2.3-2.4 times. Dualmesh(®) was the least anisotropic mesh, without marked difference between the axes. Anisotropy of synthetic meshes has been underappreciated. In this study, we found striking differences between elastic properties of perpendicular axes for most commonly used synthetic meshes. Indiscriminate orientation of anisotropic mesh may adversely affect hernia repairs. Proper labeling of all implants by manufacturers should be mandatory. Understanding the specific anisotropic behavior of synthetic meshes should allow surgeons to employ rational implant orientation to maximize outcomes of hernia repair.

Determination of the axial and circumferential mechanical properties of the skin tissue using experimental testing and constitutive modeling.

PubMed

Karimi, Alireza; Navidbakhsh, Mahdi; Haghighatnama, Maedeh; Haghi, Afsaneh Motevalli

2015-01-01

The skin, being a multi-layered material, is responsible for protecting the human body from the mechanical, bacterial, and viral insults. The skin tissue may display different mechanical properties according to the anatomical locations of a body. However, these mechanical properties in different anatomical regions and at different loading directions (axial and circumferential) of the mice body to date have not been determined. In this study, the axial and circumferential loads were imposed on the mice skin samples. The elastic modulus and maximum stress of the skin tissues were measured before the failure occurred. The nonlinear mechanical behavior of the skin tissues was also computationally investigated through a suitable constitutive equation. Hyperelastic material model was calibrated using the experimental data. Regardless of the anatomic locations of the mice body, the results revealed significantly different mechanical properties in the axial and circumferential directions and, consequently, the mice skin tissue behaves like a pure anisotropic material. The highest elastic modulus was observed in the back skin under the circumferential direction (6.67 MPa), while the lowest one was seen in the abdomen skin under circumferential loading (0.80 MPa). The Ogden material model was narrowly captured the nonlinear mechanical response of the skin at different loading directions. The results help to understand the isotropic/anisotropic mechanical behavior of the skin tissue at different anatomical locations. They also have implications for a diversity of disciplines, i.e., dermatology, cosmetics industry, clinical decision making, and clinical intervention.

A review of mechanical and tribological behaviour of polymer composite materials

NASA Astrophysics Data System (ADS)

Prabhakar, K.; Debnath, S.; Ganesan, R.; Palanikumar, K.

2018-04-01

Composite materials are finding increased applications in many industrial applications. A nano-composite is a matrix to which nanosized particles have been incorporated to drastically improve the mechanical performance of the original material. The structural components produced using nano-composites will exhibit a high strength-to-weight ratio. The properties of nano-composites have caused researchers and industries to consider using this material in several fields. Polymer nanocomposites consists of a polymer material having nano-particles or nano-fillers dispersed in the polymer matrix which may be of different shapes with at least one of the dimensions less than 100nm. In this paper, comprehensive review of polymer nanocomposites was done majorly in three different areas. First, mechanical behaviour of polymer nanocomposites which focuses on the mechanical property evaluation such as tensile strength, impact strength and modulus of elasticity based on the different combination of filler materials and nanoparticle inclusion. Second, wear behavior of Polymer composite materials with respect to different impingement angles and variation of filler composition using different processing techniques. Third, tribological (Friction and Wear) behaviour of nanocomposites using various combination of nanoparticle inclusion and time. Finally, it summarized the challenges and prospects of polymer nanocomposites.

Hypervelocity penetration against mechanical properties of target materials

NASA Astrophysics Data System (ADS)

Ariffin, M. M.; Roslan, M. H.; Ishak, M. T.; Hamid, M. H. A.; Katim, N. I. A.; Hashim, F. R.; Razali, S.

2018-02-01

Sustainable development is growing importance issues nowadays and requires the consideration of environmental criteria to develop of all new materials and equipment. A better balance must be found in properties of oils so that the impact on the environment can be minimized. In transformers, a stable liquid, inert, with good electrical and thermal properties is necessary and the liquid must be non-toxic to environment and readily biodegradable. The objective of this research is to make a comparative study of different vegetable oils: palm oil, corn oil, rice bran oil and analyze the dielectric properties such as relative permittivity, dielectric constant and resistivity with variation temperature 30°C-90°C and breakdown voltage with different ageing time 30 days, 90 days and 180 days. The dielectric properties data of the vegetable oils are compared with the transformer oil (mineral oil) and appropriate causes for similarities and different have been discussed.

Construction patterns of birds' nests provide insight into nest-building behaviours.

PubMed

Biddle, Lucia; Goodman, Adrian M; Deeming, D Charles

2017-01-01

Previous studies have suggested that birds and mammals select materials needed for nest building based on their thermal or structural properties, although the amounts or properties of the materials used have been recorded for only a very small number of species. Some of the behaviours underlying the construction of nests can be indirectly determined by careful deconstruction of the structure and measurement of the biomechanical properties of the materials used. Here we examined this idea in an investigation of Bullfinch ( Pyrrhula pyrrhula ) nests as a model for open-nesting songbird species that construct a "twig" nest, and tested the hypothesis that materials in different parts of nests serve different functions. The quantities of materials present in the nest base, sides and cup were recorded before structural analysis. Structural analysis showed that the base of the outer nests were composed of significantly thicker, stronger and more rigid materials compared to the side walls, which in turn were significantly thicker, stronger and more rigid than materials used in the cup. These results suggest that the placement of particular materials in nests may not be random, but further work is required to determine if the final structure of a nest accurately reflects the construction process.

Acoustic identification of the elastic properties of porous and nonporous superconducting materials DyBa2-XSrXCu3O7-δ

NASA Astrophysics Data System (ADS)

Sayoud, N.; Lazri, H.; Ogam, E.; Boumaiza, Y.; Boudour, A.

2018-05-01

This work involves the development of a method using the principle of acoustic microscopy to determine the elastic properties of high-temperature superconducting materials, the method is applied to analyse the variation of the elastic properties of the superconducting alloy DyBa 2-x Sr x Cu 3 O 7‑δ for different variations of the concentration parameters (x = 0, x = 0.3 and x = 0.6), porosity and temperature. The method is based on the reconstruction of the reflection coefficient calculated from the acoustic signature of the signal received by the microscope during the exploration of the superconducting material for different concentrations. This permitted the determination of the velocities of the surface and volume waves from the modelled reflection coefficient. On the other hand, the elastic parameters of the material such as Young’s, shear and bulk moduli were also deduced.

Near-infrared long-persistent phosphor of Zn₃Ga ₂Ge ₂O₁₀: Cr³⁺ sintered in different atmosphere.

PubMed

Wu, Yiling; Li, Yang; Qin, Xixi; Chen, Ruchun; Wu, Dakun; Liu, Shijian; Qiu, Jianrong

2015-01-01

A variety of materials sintered in different atmosphere have been well investigated, but there are few reports on the long-persistent phosphorescent materials, especially the near-infrared long-persistent phosphorescent materials sintered in various atmosphere. Changing the surrounding atmosphere is an effective method to improve the afterglow properties of the materials. In this work, we fabricate a typical kind of near-infrared long-persistent phosphorescent materials of Zn3Ga2Ge2O10: 0.5% Cr(3+) in neutral, oxidizing, and reducing atmosphere. By analyzing the XRD patterns, afterglow spectra, decay and thermo-luminescence curves, we discuss the great effects on the structure, long persistent properties and trap properties of the phosphor. This work of obtaining the Zn3Ga2Ge2O10: 0.5% Cr(3+) is of great potential in the applications in night-vision surveillance and in vivo bio-imaging. Copyright © 2015 Elsevier B.V. All rights reserved.

Formation of Triboelectric Series via Atomic-Level Surface Functionalization for Triboelectric Energy Harvesting.

PubMed

Shin, Sung-Ho; Bae, Young Eun; Moon, Hyun Kyung; Kim, Jungkil; Choi, Suk-Ho; Kim, Yongho; Yoon, Hyo Jae; Lee, Min Hyung; Nah, Junghyo

2017-06-27

Triboelectric charging involves frictional contact of two different materials, and their contact electrification usually relies on polarity difference in the triboelectric series. This limits the choices of materials for triboelectric contact pairs, hindering research and development of energy harvest devices utilizing triboelectric effect. A progressive approach to resolve this issue involves modification of chemical structures of materials for effectively engineering their triboelectric properties. Here, we describe a facile method to change triboelectric property of a polymeric surface via atomic-level chemical functionalizations using a series of halogens and amines, which allows a wide spectrum of triboelectric series over single material. Using this method, tunable triboelectric output power density is demonstrated in triboelectric generators. Furthermore, molecular-scale calculation using density functional theory unveils that electrons transferred through electrification are occupying the PET group rather than the surface functional group. The work introduced here would open the ability to tune triboelectric property of materials by chemical modification of surface and facilitate the development of energy harvesting devices and sensors exploiting triboelectric effect.

Colloidal Inorganic Nanocrystal Based Nanocomposites: Functional Materials for Micro and Nanofabrication

PubMed Central

Ingrosso, Chiara; Panniello, AnnaMaria; Comparelli, Roberto; Curri, Maria Lucia; Striccoli, Marinella

2010-01-01

The unique size- and shape-dependent electronic properties of nanocrystals (NCs) make them extremely attractive as novel structural building blocks for constructing a new generation of innovative materials and solid-state devices. Recent advances in material chemistry has allowed the synthesis of colloidal NCs with a wide range of compositions, with a precise control on size, shape and uniformity as well as specific surface chemistry. By incorporating such nanostructures in polymers, mesoscopic materials can be achieved and their properties engineered by choosing NCs differing in size and/or composition, properly tuning the interaction between NCs and surrounding environment. In this contribution, different approaches will be presented as effective opportunities for conveying colloidal NC properties to nanocomposite materials for micro and nanofabrication. Patterning of such nanocomposites either by conventional lithographic techniques and emerging patterning tools, such as ink jet printing and nanoimprint lithography, will be illustrated, pointing out their technological impact on developing new optoelectronic and sensing devices.

Cardiovascular Computed Tomography Phantom Fabrication and Characterization through the Tailored Properties of Polymeric Composites and Cellular Foams

NASA Astrophysics Data System (ADS)

Hoy, Carlton F. O.

The overall objective of this thesis was to control the fabrication technique and relevant material properties for phantom devices designated for computed tomography (CT) scanning. Fabrication techniques using polymeric composites and foams were detailed together with parametric studies outlining the fundamentals behind the changes in material properties which affect the characteristic CT number. The composites fabricated used polyvinylidene fluoride (PVDF), thermoplastic polyurethane (TPU) and polyethylene (PE) with hydroxylapatite (hA) as additive with different composites made by means of different weight percentages of additive. Polymeric foams were fabricated through a batch foaming technique with the heating time controlled to create different levels of foams. Finally, the effect of fabricated phantoms under varied scanning media was assessed to determine whether self-made phantoms can be scanned accurately under non-water or rigid environments allowing for the future development of complex shaped or fragile material types.

An unusual type of polymorphism in a liquid crystal

DOE PAGES

Li, Lin; Salamonczyk, Miroslaw; Shadpour, Sasan; ...

2018-02-19

Polymorphism is a remarkable concept in chemistry, materials science, computer science, and biology. Whether it is the ability of a material to exist in two or more crystal structures, a single interface connecting to two different entities, or alternative phenotypes of an organism, polymorphism determines function and properties. In materials science, polymorphism can be found in an impressively wide range of materials, including crystalline materials, minerals, metals, alloys, and polymers. Here in this paper we report on polymorphism in a liquid crystal. A bent-core liquid crystal with a single chiral side chain forms two structurally and morphologically significantly different liquidmore » crystal phases solely depending on the cooling rate from the isotropic liquid state. On slow cooling, the thermodynamically more stable oblique columnar phase forms, and on rapid cooling, a not heretofore reported helical microfilament phase. Since structure determines function and properties, the structural color for these phases also differs.« less

Steady State Structural Analysis of High Pressure Gas Turbine Blade using Finite Element Analysis

NASA Astrophysics Data System (ADS)

Mazarbhuiya, Hussain Mahamed Sahed Mostafa; Murari Pandey, Krishna

2017-08-01

In gas turbines the major portion of performance dependency lies upon turbine blade design. Turbine blades experience very high centrifugal, axial and tangential force during power generation. While withstanding these forces blades undergo elongation. Different methods have proposed for better enhancement of the mechanical properties of blade to withstand in extreme condition. Present paper describes the stress and elongation for blades having properties of different materials. Steady state structural analysis have performed in the present work for different materials (In 625, In 718, In 738, In 738 LC, MAR M246, Ni-Cr, Ti-alloy, Ti-Al, Ti-T6, U500). Remarkable finding is that the root of the blade is subjected to maximum stress for all blade materials and the blade made of MAR M246 has less stress and deformation among all other blade materials which can be selected as a suitable material for gas turbine blade.

An unusual type of polymorphism in a liquid crystal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Lin; Salamonczyk, Miroslaw; Shadpour, Sasan

Polymorphism is a remarkable concept in chemistry, materials science, computer science, and biology. Whether it is the ability of a material to exist in two or more crystal structures, a single interface connecting to two different entities, or alternative phenotypes of an organism, polymorphism determines function and properties. In materials science, polymorphism can be found in an impressively wide range of materials, including crystalline materials, minerals, metals, alloys, and polymers. Here in this paper we report on polymorphism in a liquid crystal. A bent-core liquid crystal with a single chiral side chain forms two structurally and morphologically significantly different liquidmore » crystal phases solely depending on the cooling rate from the isotropic liquid state. On slow cooling, the thermodynamically more stable oblique columnar phase forms, and on rapid cooling, a not heretofore reported helical microfilament phase. Since structure determines function and properties, the structural color for these phases also differs.« less

Intellectual Property.

ERIC Educational Resources Information Center

Swinson, John V.

2000-01-01

Intellectual property is a term that covers a number of different rights. Considers issues such as what are the basic forms of intellectual property; who owns the intellectual property created by a teacher; who owns intellectual property created by students; and use of downloaded materials from the internet. (Author/LM)

A new tensile impact test for the toughness characterization of sheet material

NASA Astrophysics Data System (ADS)

Könemann, Markus; Lenz, David; Brinnel, Victoria; Münstermann, Sebastian

2018-05-01

In the past, the selection of suitable steels has been carried out primarily based on the mechanical properties of different steels. One of these properties is the resistance against crack propagation. For many constructions, this value plays an important role, because it can compare the impact toughness of different steel grades easily and gives information about the loading capacity of the specific materials. For thin sheets, impact toughness properties were usually not considered. One of the reasons for this is that the Charpy-impact test is not applicable for sheets with thicknesses below 2 mm. For a long time, this was not relevant because conventional steels had a sufficient impact toughness in a wide temperature range. However, since new multiphase steel grades with improved mechanical property exploitations are available, it turned out that impact toughness properties need to be considered during the component design phase, as the activation of the cleavage fracture mechanism is observed under challenging loading conditions. Therefore, this work aims to provide a new and practical testing procedure for sheet material or thin walled structures. The new testing procedure is based on tensile tests conducted in an impact pendulum similar to the Charpy impact hammer. A new standard geometry is provided, which enables a comparison between different steels or steel grades. A connection to the conventional Charpy test is presented using a damage mechanics model, which predicts material failure with consideration of to the stress state at various temperatures. Different specimen geometries are analysed to cover manifold stress states. A special advantage of the damage mechanics model is also the possibility to predict the materials behaviour in the transition area. To verify the method a conventional steel was tested in Charpy tests as well as in the new tensile impact test.

Electrical percolation threshold of cementitious composites possessing self-sensing functionality incorporating different carbon-based materials

NASA Astrophysics Data System (ADS)

Al-Dahawi, Ali; Haroon Sarwary, Mohammad; Öztürk, Oğuzhan; Yıldırım, Gürkan; Akın, Arife; Şahmaran, Mustafa; Lachemi, Mohamed

2016-10-01

An experimental study was carried out to understand the electrical percolation thresholds of different carbon-based nano- and micro-scale materials in cementitious composites. Multi-walled carbon nanotubes (CNTs), graphene nanoplatelets (GNPs) and carbon black (CB) were selected as the nano-scale materials, while 6 and 12 mm long carbon fibers (CF6 and CF12) were used as the micro-scale carbon-based materials. After determining the percolation thresholds of different electrical conductive materials, mechanical properties and piezoresistive properties of specimens produced with the abovementioned conductive materials at percolation threshold were investigated under uniaxial compressive loading. Results demonstrate that regardless of initial curing age, the percolation thresholds of CNT, GNP, CB and CFs in ECC mortar specimens were around 0.55%, 2.00%, 2.00% and 1.00%, respectively. Including different carbon-based conductive materials did not harm compressive strength results; on the contrary, it improved overall values. All cementitious composites produced with carbon-based materials, with the exception of the control mixtures, exhibited piezoresistive behavior under compression, which is crucial for sensing capability. It is believed that incorporating the sensing attribute into cementitious composites will enhance benefits for sustainable civil infrastructures.

Inorganic fullerenes and nanotubes: Wealth of materials and morphologies

NASA Astrophysics Data System (ADS)

Bar-Sadan, M.; Kaplan-Ashiri, I.; Tenne, R.

2007-10-01

It is already well established today that numerous materials form closed-cage structures, of which carbon fullerenes and nanotubes are a special case [1]. Inorganic fullerene-like nanoparticles (designated IF) and inorganic nanotubes (INT) have been produced by different routes and experimental techniques, achieving persistent growth of a variety of materials and structural wealth within them. The research in this area has focused on synthesizing new IF and INT materials and understanding their different properties as well as scaling up the synthetic process in order to make it suitable for industrial applications. In this review, the main synthetic procedures to obtain inorganic fullerene-like nanoparticles and nanotubes will be discussed alongside with the different mechanisms that affect the morphology of the final product. The main differences between the morphologies will be presented. Some general considerations relating the properties of the parent compound with the morphology of the product will be mentioned.

The Utilization of Graphene Oxide in Traditional Construction Materials: Asphalt.

PubMed

Zeng, Wenbo; Wu, Shaopeng; Pang, Ling; Sun, Yihan; Chen, Zongwu

2017-01-07

In the advanced research fields of solar cell and energy storing materials, graphene and graphene oxide (GO) are two of the most promising materials due to their high specific surface area, and excellent electrical and physical properties. However, they was seldom studied in the traditional materials because of their high cost. Nowadays, graphene and GO are much cheaper than before with the development of production technologies, which provides the possibility of using these extraordinary materials in the traditional construction industry. In this paper, GO was selected as a nano-material to modify two different asphalts. Then a thin film oven test and a pressure aging vessel test were applied to simulate the aging of GO-modified asphalts. After thermal aging, basic physical properties (softening point and penetration) were tested for the samples which were introduced at different mass ratios of GO (1% and 3%) to asphalt. In addition, rheological properties were tested to investigate how GO could influence the asphalts by dynamic shearing rheometer tests. Finally, some interesting findings and potential utilization (warm mixing and flame retardants) of GO in asphalt pavement construction were explained.

The Utilization of Graphene Oxide in Traditional Construction Materials: Asphalt

PubMed Central

Zeng, Wenbo; Wu, Shaopeng; Pang, Ling; Sun, Yihan; Chen, Zongwu

2017-01-01

In the advanced research fields of solar cell and energy storing materials, graphene and graphene oxide (GO) are two of the most promising materials due to their high specific surface area, and excellent electrical and physical properties. However, they was seldom studied in the traditional materials because of their high cost. Nowadays, graphene and GO are much cheaper than before with the development of production technologies, which provides the possibility of using these extraordinary materials in the traditional construction industry. In this paper, GO was selected as a nano-material to modify two different asphalts. Then a thin film oven test and a pressure aging vessel test were applied to simulate the aging of GO-modified asphalts. After thermal aging, basic physical properties (softening point and penetration) were tested for the samples which were introduced at different mass ratios of GO (1% and 3%) to asphalt. In addition, rheological properties were tested to investigate how GO could influence the asphalts by dynamic shearing rheometer tests. Finally, some interesting findings and potential utilization (warm mixing and flame retardants) of GO in asphalt pavement construction were explained. PMID:28772406

PSIDD3: Post-Scan Ultrasonic Data Display System for the Windows-Based PC Including Fuzzy Logic Analysis

NASA Technical Reports Server (NTRS)

Lovelace, Jeffrey J.; Cios, Krzysztof J.; Roth, Don J.; Cao, Wei

2000-01-01

Post-Scan Interactive Data Display (PSIDD) III is a user-oriented Windows-based system that facilitates the display and comparison of ultrasonic contact data. The system is optimized to compare ultrasonic measurements made at different locations within a material or at different stages of material degradation. PSIDD III provides complete analysis of the primary wave forms in the time and frequency domains along with the calculation of several frequency dependent properties including Phase Velocity and Attenuation Coefficient and several frequency independent properties, like the Cross Correlation Velocity. The system allows image generation on all of the frequency dependent properties at any available frequency (limited by the bandwidth used in the scans) and on any of the frequency independent properties. From ultrasonic contact scans, areas of interest on an image can be studied with regard to underlying raw waveforms and derived ultrasonic properties by simply selecting the point on the image. The system offers various modes of in-depth comparison between scan points. Up to five scan points can be selected for comparative analysis at once. The system was developed with Borland Delphi software (Visual Pascal) and is based on a SQL database. It is ideal for classification of material properties, or location of microstructure variations in materials.

Effect of crosslinking concentration on properties of 3-(trimethoxysilyl) propyl methacrylate/N-vinyl pyrrolidone gels.

PubMed

Mohammed, Ameen Hadi; Ahmad, Mansor B; Ibrahim, Nor Azowa; Zainuddin, Norhazlin

2018-02-13

The incorporation of two different monomers, having different properties, in the same polymer molecule leads to the formation of new materials with great scientific and commercial importance. The basic requirements for polymeric materials in some areas of biomedical applications are that they are hydrophilic, having good mechanical and thermal properties, soft, and oxygen-permeable. A series of 3-(trimethoxysilyl) propyl methacrylate/N-vinyl pyrrolidone (TMSPM/NVP) xerogels containing different concentration of ethylene glycol dimethacrylate (EGDMA) as crosslinking agent were prepared by bulk polymerization to high conversion using BPO as initiator. The copolymers were characterized by FTIR. The corresponding hydrogels were obtained by swelling the xerogels in deionized water to equilibrium. Addition of EGDMA increases the transparency of xerogels and hydrogels. The minimum amount of EGDMA required to produce a transparent xerogel is 1%. All the Swelling parameters, including water content (EWC), volume fraction of polymer (ϕ 2 ) and weight loss during swelling decrease with increasing EGDMA. Young's and shear modulus (E and G) increase as EGDMA increases. The hydrogels were characterized in terms of modulus cross-linking density (v e and v t ) and polymer-solvent interaction parameters (χ). Thermal properties include TGA and glass transition temperature (T g ) enhance by adding EGDMA whereas the oxygen permeability (P) of hydrogels decreases as water content decrease. This study prepared and studied the properties for new copolymer (TMSPM-co-NVP) contains different amounts of (EGDMA). These copolymers possess new properties with potential use in different biomedical applications. The properties of the prepared hydrogels are fit with the standard properties of materials which should be used for contact lenses.

Dependence of behavioral performance on material category in an object grasping task with monkeys.

PubMed

Yokoi, Isao; Tachibana, Atsumichi; Minamimoto, Takafumi; Goda, Naokazu; Komatsu, Hidehiko

2018-05-02

Material perception is an essential part of our cognitive function that enables us to properly interact with our complex daily environment. One important aspect of material perception is its multimodal nature. When we see an object, we generally recognize its haptic properties as well as its visual properties. Consequently, one must examine behavior using real objects that are perceived both visually and haptically to fully understand the characteristics of material perception. As a first step, we examined whether there is any difference in the behavioral responses to different materials in monkeys trained to perform an object grasping task in which they saw and grasped rod-shaped real objects made of various materials. We found that the monkeys' behavior in the grasping task, measured based on the success rate and the pulling force, differed depending on the material category. Monkeys easily and correctly grasped objects of some materials, such as metal and glass, but failed to grasp objects of other materials. In particular, monkeys avoided grasping fur-covered objects. The differences in the behavioral responses to the material categories cannot be explained solely based on the degree of familiarity with the different materials. These results shed light on the organization of multimodal representation of materials, where their biological significance is an important factor. In addition, a monkey that avoided touching real fur-covered objects readily touched images of the same objects presented on a CRT display. This suggests employing real objects is important when studying behaviors related to material perception.

Growth-dependent effects of dietary protein concentration and quality on the biomechanical properties of the diaphyseal rat femur.

PubMed

Alippi, Rosa M; Picasso, Emilio; Huygens, Patricia; Bozzini, Carlos E; Bozzini, Clarisa

2012-01-01

This study compares the effects of feeding growing rats with increasing concentrations of casein (C) and wheat gluten (G), proteins that show different biological qualities, on the morphometrical and biomechanical properties of the femoral diaphysis. Female rats were fed with one of ten diets containing different concentrations (5-30%) of C and G between the 30th and 90th days of life (Control=C-20%). Biomechanical structural properties of the right femur middiaphysis were estimated using a 3-point bending mechanical test with calculation of some indicators of bone material properties. Body weight and length were affected by treatments, values being highest in rats fed the C-20% diet. G diets affected negatively both parameters. Changes in cross-sectional geometry (mid-diaphyseal cross-sectional and cortical areas, femoral volume, and rectangular moment of inertia) were positively related to the C content of the diet, while they were severely and negatively affected by G diets. Similar behaviors were observed in the bone structural properties (fracture load, yielding load, diaphyseal stiffness and elastic energy absorption). When values of strength and stiffness were normalized for body weight, the differences disappeared. The bone material quality indicators (elastic modulus, yielding stress, elastic energy absorption/volume) did not differ significantly among all studied groups. Femoral calcium concentration in ashes was not significantly different among groups. The clear differences in strength and stiffness of bone beams induced by dietary protein concentration and quality seemed to be the result of an induced subnormal gain in bone structural properties as a consequence of a correlative subnormal gain in bone growth and mass, yet not in bone material properties. Copyright © 2011 SEEN. Published by Elsevier Espana. All rights reserved.

A review of catalyst-enhanced magnesium hydride as a hydrogen storage material

NASA Astrophysics Data System (ADS)

Webb, C. J.

2015-09-01

Magnesium hydride remains an attractive hydrogen storage material due to the high hydrogen capacity and low cost of production. A high activation energy and poor kinetics at practical temperatures for the pure material have driven research into different additives to improve the sorption properties. This review details the development of catalytic additives and their effect on the activation energy, kinetics and thermodynamic properties of magnesium hydride.

Metallic materials for mechanical damping capacity applications

NASA Astrophysics Data System (ADS)

Crăciun, R. C.; Stanciu, S.; Cimpoeșu, R.; (Dragoș Ursanu, A. I.; Manole, V.; Paraschiv, P.; Chicet, D. L.

2016-08-01

Some metallic materials exhibit good damping capacity of mechanical energy into thermal energy. This property along with the others metallic characteristics make this materials interesting for a big number of applications. These materials can be used as bumpers in different applications including automotive field. Beside grey cast iron and shape memory alloys few new metallic materials are presented for the supposition of high damping capacity. We analyze the causes that increase the internal friction of some metallic materials and possibilities to enhance this property through different mechanical, physical or chemical methods. Shape memory alloys, especially those based on copper, present a different damping capacity on martensite, austenite or transition state. In the transformation range M ↔A, which in case of copper base shape memory alloys is quite large, the metallic intelligent materials present a high internal friction, almost comparable with natural rubber behavior that can transform mechanical energy into thermal energy till a certain value of the external solicitation. These materials can be used as noise or small vibrations bumpers or even as shock absorbers in automotive industry.

Controlled surface functionality of magnetic nanoparticles by layer-by-layer assembled nano-films

NASA Astrophysics Data System (ADS)

Choi, Daheui; Son, Boram; Park, Tai Hyun; Hong, Jinkee

2015-04-01

Over the past several years, the preparation of functionalized nanoparticles has been aggressively pursued in order to develop desired structures, compositions, and structural order. Among the various nanoparticles, iron oxide magnetic nanoparticles (MNPs) have shown great promise because the material generated using these MNPs can be used in a variety of biomedical applications and possible bioactive functionalities. In this study, we report the development of various functionalized MNPs (F-MNPs) generated using the layer-by-layer (LbL) self-assembly method. To provide broad functional opportunities, we fabricated F-MNP bio-toolbox by using three different materials: synthetic polymers, natural polymers, and carbon materials. Each of these F-MNPs displays distinct properties, such as enhanced thickness or unique morphologies. In an effort to explore their biomedical applications, we generated basic fibroblast growth factor (bFGF)-loaded F-MNPs. The bFGF-loaded F-MNPs exhibited different release mechanisms and loading amounts, depending on the film material and composition order. Moreover, bFGF-loaded F-MNPs displayed higher biocompatibility and possessed superior proliferation properties than the bare MNPs and pure bFGF, respectively. We conclude that by simply optimizing the building materials and the nanoparticle's film composition, MNPs exhibiting various bioactive properties can be generated.Over the past several years, the preparation of functionalized nanoparticles has been aggressively pursued in order to develop desired structures, compositions, and structural order. Among the various nanoparticles, iron oxide magnetic nanoparticles (MNPs) have shown great promise because the material generated using these MNPs can be used in a variety of biomedical applications and possible bioactive functionalities. In this study, we report the development of various functionalized MNPs (F-MNPs) generated using the layer-by-layer (LbL) self-assembly method. To provide broad functional opportunities, we fabricated F-MNP bio-toolbox by using three different materials: synthetic polymers, natural polymers, and carbon materials. Each of these F-MNPs displays distinct properties, such as enhanced thickness or unique morphologies. In an effort to explore their biomedical applications, we generated basic fibroblast growth factor (bFGF)-loaded F-MNPs. The bFGF-loaded F-MNPs exhibited different release mechanisms and loading amounts, depending on the film material and composition order. Moreover, bFGF-loaded F-MNPs displayed higher biocompatibility and possessed superior proliferation properties than the bare MNPs and pure bFGF, respectively. We conclude that by simply optimizing the building materials and the nanoparticle's film composition, MNPs exhibiting various bioactive properties can be generated. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr07373h

Why the dish makes a difference: quantitative comparison of polystyrene culture surfaces.

PubMed

Zeiger, Adam S; Hinton, Benjamin; Van Vliet, Krystyn J

2013-07-01

There is wide anecdotal recognition that biological cell viability and behavior can vary significantly as a function of the source of commercial tissue culture polystyrene (TCPS) culture vessels to which those cells adhere. However, this marked material dependency is typically resolved by selecting and then consistently using the same manufacturer's product - following protocol - rather than by investigating the material properties that may be responsible for such experimental variation. Here, we quantified several physical properties of TCPS surfaces obtained from a wide range of commercial sources and processing steps, through the use of atomic force microscopy (AFM)-based imaging and analysis, goniometry and protein adsorption quantification. We identify qualitative differences in surface features, as well as quantitative differences in surface roughness and wettability that cannot be attributed solely to differences in surface chemistry. We also find significant differences in cell morphology and proliferation among cells cultured on different TCPS surfaces, and resolve a correlation between nanoscale surface roughness and cell proliferation rate for both cell types considered. Interestingly, AFM images of living adherent cells on these nanotextured surfaces demonstrate direct interactions between cellular protrusions and topographically distinct features. These results illustrate and quantify the significant differences in material surface properties among these ubiquitous materials, allowing us to better understand why the dish can make a difference in biological experiments. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Molecular deformation mechanisms of the wood cell wall material.

PubMed

Jin, Kai; Qin, Zhao; Buehler, Markus J

2015-02-01

Wood is a biological material with outstanding mechanical properties resulting from its hierarchical structure across different scales. Although earlier work has shown that the cellular structure of wood is a key factor that renders it excellent mechanical properties at light weight, the mechanical properties of the wood cell wall material itself still needs to be understood comprehensively. The wood cell wall material features a fiber reinforced composite structure, where cellulose fibrils act as stiff fibers, and hemicellulose and lignin molecules act as soft matrix. The angle between the fiber direction and the loading direction has been found to be the key factor controlling the mechanical properties. However, how the interactions between theses constitutive molecules contribute to the overall properties is still unclear, although the shearing between fibers has been proposed as a primary deformation mechanism. Here we report a molecular model of the wood cell wall material with atomistic resolution, used to assess the mechanical behavior under shear loading in order to understand the deformation mechanisms at the molecular level. The model includes an explicit description of cellulose crystals, hemicellulose, as well as lignin molecules arranged in a layered nanocomposite. The results obtained using this model show that the wood cell wall material under shear loading deforms in an elastic and then plastic manner. The plastic regime can be divided into two parts according to the different deformation mechanisms: yielding of the matrix and sliding of matrix along the cellulose surface. Our molecular dynamics study provides insights of the mechanical behavior of wood cell wall material at the molecular level, and paves a way for the multi-scale understanding of the mechanical properties of wood. Copyright © 2014 Elsevier Ltd. All rights reserved.

The Effect of Different Mixing Methods on Working Time, Setting Time, Dimensional Changes and Film Thickness of Mineral Trioxide Aggregate and Calcium-Enriched Mixture.

PubMed

Shahi, Shahriar; Ghasemi, Negin; Rahimi, Saeed; Yavari, Hamidreza; Janani, Maryam; Mokhtari, Hadi; Bahari, Mahmood; Rabbani, Parastu

2015-01-01

The aim of the present study was to evaluate the effect of different mixing techniques (conventional, amalgamator and ultrasonic mixing) on the physical properties the working time (WT), setting time (ST), dimensional changes (DC) and film thickness (FT)] of calcium-enriched mixture (CEM) cement and mineral trioxide aggregate (MTA). The mentioned physical properties were determined using the ISO 6786:2001 specification. Six samples of each material were prepared for three mixing techniques (totally 36 samples). Data were analyzed using descriptive statistics, two-way ANOVA and Post Hoc Tukey's tests. The level of significance was defined at 0.05. Irrespective of mixing technique, there was no significant difference between the WT and FT of the tested materials. Except for the DC of MTA and the FT of the all materials, other properties were significantly affected with mixing techniques (P<0.05). The ultrasonic technique decreased the ST of MTA and CEM cement and increased the WT of CEM cement (P<0.05). The mixing technique of the materials had no significant effect on the dimensional changes of MTA and the film thickness of both materials.

Evaluation of chitosan quaternary ammonium salt-modified resin denture base material.

PubMed

Song, Rong; Zhong, Zhaohua; Lin, Lexun

2016-04-01

Chitosan quaternary ammonium salt displays good antioxidant and antibacterial characteristics and it shows appreciable solubility in water. When added to the traditional denture material to form a resin base, it could promote good oral health by improving the oral environment. In this study, chitosan quaternary ammonium salt was added to the denture material following two different methods. After three months of immersion in artificial saliva, the specimens were tested for tensile strength and were scanned by electron microscope. The murine fibroblast cytotoxicity and antibacterial properties were also tested. The result showed no significant differences in the tensile strength and in the proliferation of murine L929 fibroblast cells. The two structures of chitosan quaternary ammonium salt-modified denture material had different degrees of corrosion resistance and antimicrobial properties. These results indicate that chitosan quaternary ammonium salt-modified resin denture base material has the potential to become a new generation oral denture composite material. Copyright © 2015 Elsevier B.V. All rights reserved.

Evaluation of the surface free energy of plant surfaces: toward standardizing the procedure

PubMed Central

Fernández, Victoria; Khayet, Mohamed

2015-01-01

Plant surfaces have been found to have a major chemical and physical heterogeneity and play a key protecting role against multiple stress factors. During the last decade, there is a raising interest in examining plant surface properties for the development of biomimetic materials. Contact angle measurement of different liquids is a common tool for characterizing synthetic materials, which is just beginning to be applied to plant surfaces. However, some studies performed with polymers and other materials showed that for the same surface, different surface free energy values may be obtained depending on the number and nature of the test liquids analyzed, materials' properties, and surface free energy calculation methods employed. For 3 rough and 3 rather smooth plant materials, we calculated their surface free energy using 2 or 3 test liquids and 3 different calculation methods. Regardless of the degree of surface roughness, the methods based on 2 test liquids often led to the under- or over-estimation of surface free energies as compared to the results derived from the 3-Liquids method. Given the major chemical and structural diversity of plant surfaces, it is concluded that 3 different liquids must be considered for characterizing materials of unknown physico-chemical properties, which may significantly differ in terms of polar and dispersive interactions. Since there are just few surface free energy data of plant surfaces with the aim of standardizing the calculation procedure and interpretation of the results among for instance, different species, organs, or phenological states, we suggest the use of 3 liquids and the mean surface tension values provided in this study. PMID:26217362

Effect of processing history on the surface interfacial properties of budesonide in carrier-based dry-powder inhalers.

PubMed

Shur, Jagdeep; Pitchayajittipong, Chonladda; Rogueda, Philippe; Price, Robert

2013-08-01

Influence of air-jet micronization, post-micronization conditioning and storage on the surface properties of budesonide in dry-powder inhaler formulations was investigated. Crystalline budesonide was air jet-micronized and conditioned using organic vapor. Particle engineering was also used to fabricate respirable particles of budesonide. Surface imaging by atomic force microscopy suggested that micronized material possessed process-induced surface disorder, which relaxed upon conditioning with organic vapor. Particle engineered material was devoid of such surface disorder. Surface interfacial properties of all batches were different and correlated to in vitro fine particle delivery. The surface properties and in vitro performance of the conditioned material changed upon storage of the budesonide at 44% relative humidity and 25°C, while the micronized and particle-engineered material remained stable. These data suggest that processing conditions of budesonide affected the surface properties of the material, which was demonstrated to have direct affect on dry-powder inhaler formulation performance.

Controlling Structure and Properties of High Surface Area Nonwoven Materials via Hydroentangling

NASA Astrophysics Data System (ADS)

Luzius, Dennis

Hydroentangling describes a technique using a series of high-velocity water jets to mechanically interlock and entangle fibers. Over the last decades researchers worked on a fundamental understanding of the process and the factors influencing the properties of the final nonwoven material. Recent studies discovered hydroentangling to be capable to create unique, knot-like structures characterized by high- and low density regions, which are believed to have interesting properties for filtration applications. However, just little is known about the impact of hydroentangling parameters on the properties of filtration media to this day. In this study we report on the effect of various hydroentangling parameters, such as jet spacing, manifold pressure, number of manifolds but also specific energy on the structure and properties of high surface area nonwoven materials. Latter was achieved by different bicomponent fiber technologies and subsequent treatments removing the sacrificial compound from the structure. The highest BET surface area was measured to be 3.5 m2 g-1 and the smallest mean fiber size about 0.5 mum. Hydroentangling with large jet spacing was found to be a parameter significantly enhancing the filtration properties of caustic-treated island-in-the-sea nonwoven materials. Moreover, improved capture efficiencies and reduced pressure drops were achieved by reducing the manifold pressure and therefore specific energy during hydroentangling. Jet spacing but not island count was found to be the dominant factor influencing the structure and properties of island-in-the-sea nonwovens. Contrary to our initial expectations increasing the island count and thus decreasing the fiber size did not result in better filtration properties. Mixed media nonwoven structures made from homocomponent and island-in-the-sea fibers were found to have lower densities, higher air permeabilities and better quality factors compared to island-in-the-sea structures hydroentangled under the exact same conditions. Study showed the specific energy to not be an adequate measure for describing the process-structure relationship in hydroentangling. Hydroentangling with same specific energy but different manifold pressures revealed the structure and properties to be different and the peak manifold pressure to be the dominant parameter. It was further shown that hydroentangling with multiple manifolds but same water pressure influences the structure and properties of mono- and bicomponent nonwoven materials. Hydroentangling with three manifolds having the same water pressure resulted in stronger, less permeable fabrics compared to two manifolds or one manifold with the same water pressure. Necessary hydroentangling intensity for winged and island-in-the-sea nonwoven materials was found to be different. Winged fiber nonwovens required higher manifold pressures and a different energy ratio than island-in-in-the-sea nonwovens. Hydroentangling winged fiber webs with jet spacing larger than 600 mum resulted in materials too weak to withstand the caustic-treatment. Study indicated the charging potential of winged fiber nonwovens to be superior compared to island-in-the-sea-structures. In contrast to winged fiber nonwovens, island-in-the-sea structures showed higher pressure drops after corona discharge. Loading winged fiber nonwovens with potassium chloride revealed caustic-treated, IPA discharged materials to show the highest loading capacity.

Combinatorial synthesis of inorganic or composite materials

DOEpatents

Goldwasser, Isy; Ross, Debra A.; Schultz, Peter G.; Xiang, Xiao-Dong; Briceno, Gabriel; Sun, Xian-Dong; Wang, Kai-An

2010-08-03

Methods and apparatus for the preparation and use of a substrate having an array of diverse materials in predefined regions thereon. A substrate having an array of diverse materials thereon is generally prepared by delivering components of materials to predefined regions on a substrate, and simultaneously reacting the components to form at least two materials or, alternatively, allowing the components to interact to form at least two different materials. Materials which can be prepared using the methods and apparatus of the present invention include, for example, covalent network solids, ionic solids and molecular solids. More particularly, materials which can be prepared using the methods and apparatus of the present invention include, for example, inorganic materials, intermetallic materials, metal alloys, ceramic materials, organic materials, organometallic materials, nonbiological organic polymers, composite materials (e.g., inorganic composites, organic composites, or combinations thereof), etc. Once prepared, these materials can be screened for useful properties including, for example, electrical, thermal, mechanical, morphological, optical, magnetic, chemical, or other properties. Thus, the present invention provides methods for the parallel synthesis and analysis of novel materials having useful properties.

The influence of cosmic radiation on the properties of different polymers

NASA Astrophysics Data System (ADS)

Major, Andrea Adamne; Boja, David

2017-10-01

During our research we investigated the influence of cosmic radiation on the properties of different polymers. Polypropylene, polyamide 6.6 and polycarbonate were used as raw materials. Test pieces were injection molded. The test pieces were "flying" at different heights (on Earth, at 5500 m, at 12000 m). Thermal properties were investigated: DSC and TGA. We found that cosmic relay influences change in the thermal properties of polypropylene, polyamide 6.6 and polycarbonate.

The effects of solution treatment on the mechanical properties of age-hardened A-286 bar stock at elevated and cryogenic temperature

NASA Technical Reports Server (NTRS)

Montano, J. W.

1972-01-01

The mechanical properties are presented of solution treated and age hardened A-286 corrosion resistant steel bar stock. Material solution treated at 899 C or 982 C, each followed by an age hardening treatment of 718 C, was evaluated. Test specimens manufactured from 1.50 inch (3.81 cm) diameter bar stock were tested at temperatures from +649 C to -253 C. The test data indicated excellent tensile, yield, elongation and reduction-in-area properties at all testing temperatures for both solution treated and aged materials. Cryogenic temperature notched tensile, impact, and shear tests indicated excellent notch strength, ductility, and shear values. There was very little difference in the mechanical properties of the two solution treated and aged materials. The only exception was that the 962 C solution treated and aged material had superior stress rupture properties at 649 C.

Odd–even structural sensitivity on dynamics in network-forming ionic liquids

DOE PAGES

Yang, Ke; Cai, Zhikun; Tyagi, Madhusudan; ...

2016-04-13

Understanding structural sensitivity on properties of materials is an important step toward the rational design of materials. As a compelling case of sensitive structure-property relationship, an odd-even effect refers to the alternating trend of physical or chemical properties on odd/even number of repeating structural units. In crystalline or semi-crystalline materials, such odd-even variations of macroscopic properties emerge as manifestations of differences in the periodic packing patterns of molecules. Therefore, due to the lack of long-range order, such odd-even phenomenon is not expected in liquids. Herein, we report the discovery of a remarkable odd-even effect of the dynamical properties in themore » liquid phase, which challenges the traditional periodic packing explanations. In a class of network-forming ionic liquid (NIL), using incoherent quasi-elastic neutron scattering measurements, we measured the dynamical properties including the diffusion coefficient and the rotational relaxation time. These dynamical properties showed pronounced alternating trends with increased number of methylene (–CH 2– ) groups in the backbone. Meanwhile, the structure factor S(Q) showed no long-range periodic packing of molecules, while the pair distribution function g(r) revealed subtle differences in the local molecular morphology. As a result, the observed dynamical odd-even phenomenon in liquids showed that profound dynamical changes originate from subtle local structural differences.« less

Ferroelectric self-assembled molecular materials showing both rectifying and switchable conductivity

PubMed Central

Gorbunov, Andrey V.; Garcia Iglesias, Miguel; Guilleme, Julia; Cornelissen, Tim D.; Roelofs, W. S. Christian; Torres, Tomas; González-Rodríguez, David; Meijer, E. W.; Kemerink, Martijn

2017-01-01

Advanced molecular materials that combine two or more physical properties are typically constructed by combining different molecules, each being responsible for one of the properties required. Ideally, single molecules could take care of this combined functionality, provided they are self-assembled correctly and endowed with different functional subunits whose strong electronic coupling may lead to the emergence of unprecedented and exciting properties. We present a class of disc-like semiconducting organic molecules that are functionalized with strong dipolar side groups. Supramolecular organization of these materials provides long-range polar order that supports collective ferroelectric behavior of the side groups as well as charge transport through the stacked semiconducting cores. The ferroelectric polarization in these supramolecular polymers is found to couple to the charge transport and leads to a bulk conductivity that is both switchable and rectifying. An intuitive model is developed and found to quantitatively reproduce the experimental observations. In a larger perspective, these results highlight the possibility of modulating material properties using the large electric fields associated with ferroelectric polarization. PMID:28975150

Study of the thermal properties of filaments for 3D printing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trhlíková, Lucie, E-mail: xctrhlikova@fch.vutbr.cz; Zmeskal, Oldrich, E-mail: zmeskal@fch.vutbr.cz; Florian, Pavel, E-mail: xcflorianp@fch.vutbr.cz

Various materials are used for 3D printing, most commonly Acrylonitrile butadiene styrene (ABS), Polylactic acid (PLA), Polyethylene (PET) and Polypropylene (PP). These materials differ mainly in their melting point, which significantly influences the properties of the final products. Filaments are melted in the print head during the printing process. The temperature range is from 150 °C to 250 °C depending on the technology used. The optimum temperature for the cooling substrate on which printing is carried out is chosen so as to ensure uniform cooling and deformation. It generally varies between (40 – 100) °C. From the above it ismore » clear that both temperatures can significantly affect the properties of the printed 3D object. It is therefore important to determine the thermal parameters (thermal conductivity, specific heat and thermal diffusivity) of the materials used across the entire range of temperatures. For evaluating the properties of different types of PLA materials, the step transient method was used, which allows determination of all required parameters using a fractal heat transfer model.« less

Passive and active mechanical properties of biotemplated ceramics revisited.

PubMed

Van Opdenbosch, Daniel; Fritz-Popovski, Gerhard; Plank, Johann; Zollfrank, Cordt; Paris, Oskar

2016-10-13

Living nature and human technology apply different principles to create hard, strong and tough materials. In this review, we compare and discuss prominent aspects of these alternative strategies, and demonstrate for selected examples that nanoscale-precision biotemplating is able to produce uncommon mechanical properties as well as actuating behavior, resembling to some extent the properties of the original natural templates. We present and discuss mechanical testing data showing for the first time that nanometer-precision biotemplating can lead to porous ceramic materials with deformation characteristics commonly associated with either biological or highly advanced technical materials. We also review recent findings on the relation between hierarchical structuring and humidity-induced directional motion. Finally, we discuss to which extent the observed behavior is in agreement with previous results and theories on the mechanical properties of multiscale hierarchical materials, as well as studies of highly disperse technical materials, together with an outlook for further lines of investigation.

Reactive Processing of Environment Conscious, Biomorphic Ceramics: A Novel and Eco-friendly Route to Advanced Ceramic

NASA Technical Reports Server (NTRS)

Singh, M.

2002-01-01

Environment-conscious, biomorphic ceramics (Ecoceramics) are a new class of materials that can be produced with renewable resources (wood) and wood wastes (wood sawdust). These materials have tailorable properties with numerous potential applications. Silicon carbide-based ecoceramics have been fabricated by the infiltration of wood-derived carbonaceous preforms with oxide and silicon based materials. The wood-derived carbonaceous preforms have been shown to be quite useful in producing porous or dense materials with different microstructures and compositions. The microstructure and mechanical properties (flexural strength, fracture toughness, elastic modulus, and compressive strength) of a wide variety of Sic-based ecoceramics have been measured. Ecoceramics have tailorable properties and behave like ceramic materials manufactured by conventional approaches. In this presentation the fabrication approach, microstructure, and thermomechanical properties of a wide variety of Sic-based Ecoceramics will be reported.

Finite-difference time-domain simulation of electromagnetic bandgap and bi-anisotropic metamaterials

NASA Astrophysics Data System (ADS)

Bray, Matthew G.

The term "Metamaterial" has been introduced into the electromagnetic lexicon in recent years to describe new artificial materials with electromagnetic properties that are not found in naturally occurring materials. Metamaterials exhibit electromagnetic properties that are not observed in its constituent materials, and/or not observed in nature. This thesis will analyze two different classes of metamaterials through the use of the finite-difference time-domain (FDTD) technique. The first class of metamaterials are artificial magnetic conductors (AMC) which approximate the behavior of a perfect magnetic conductor (PMC) over a finite frequency range. The AMC metamaterials are created through the use of an electromagnetic bandgap (EBG) structure. A periodic FDTD code is used to simulate a full-wave model of the metallodielectric EBG structures. The AMCs developed with the aid of the FDTD tool are then used to create low-profile antenna systems consisting of a dipole antenna in close proximity to an AMC surface. Through the use of this FDTD tool, several original contributions were made to the electromagnetic community. These include the first dual-band independently tunable EBG AMC ground plane and the first linearly polarized single-band and dual-band tunable antenna/EBG systems. The second class of materials analyzed are bi-anisotropic metamaterials. Bi-anisotropic media are the largest class of linear media which is able to describe the macroscopic material properties of artificial dielectrics, artificial magnetics, artificial chiral materials, left-handed materials, and other composite materials. The dispersive properties of these materials can be approximated by the oscillator model. This model assumes a Lorentzian frequency profile for the permittivity and permeability and a Condon model for chirality. A new FDTD formulation is introduced which can simulate this type of bi-anisotropic media. This FDTD method incorporates the dispersive material properties through a Z-transform technique derived from the constitutive relations for bi-anisotropic media. This is the first FDTD formulation to be able to simulate dispersive chiral media on a single FDTD grid. This tool was also used to perform the first simulations of dispersive chiral frequency selective surfaces.

A new approach for modeling composite materials

NASA Astrophysics Data System (ADS)

Alcaraz de la Osa, R.; Moreno, F.; Saiz, J. M.

2013-03-01

The increasing use of composite materials is due to their ability to tailor materials for special purposes, with applications evolving day by day. This is why predicting the properties of these systems from their constituents, or phases, has become so important. However, assigning macroscopical optical properties for these materials from the bulk properties of their constituents is not a straightforward task. In this research, we present a spectral analysis of three-dimensional random composite typical nanostructures using an Extension of the Discrete Dipole Approximation (E-DDA code), comparing different approaches and emphasizing the influences of optical properties of constituents and their concentration. In particular, we hypothesize a new approach that preserves the individual nature of the constituents introducing at the same time a variation in the optical properties of each discrete element that is driven by the surrounding medium. The results obtained with this new approach compare more favorably with the experiment than previous ones. We have also applied it to a non-conventional material composed of a metamaterial embedded in a dielectric matrix. Our version of the Discrete Dipole Approximation code, the EDDA code, has been formulated specifically to tackle this kind of problem, including materials with either magnetic and tensor properties.

Fusion of nacre, mussel, and lotus leaf: bio-inspired graphene composite paper with multifunctional integration

NASA Astrophysics Data System (ADS)

Zhong, Da; Yang, Qinglin; Guo, Lin; Dou, Shixue; Liu, Kesong; Jiang, Lei

2013-06-01

Multifunctional integration is an inherent characteristic for biological materials with multiscale structures. Learning from nature is an effective approach for scientists and engineers to construct multifunctional materials. In nature, mollusks (abalone), mussels, and the lotus have evolved different and optimized solutions to survive. Here, bio-inspired multifunctional graphene composite paper was fabricated in situ through the fusion of the different biological solutions from nacre (brick-and-mortar structure), mussel adhesive protein (adhesive property and reducing character), and the lotus leaf (self-cleaning effect). Owing to the special properties (self-polymerization, reduction, and adhesion), dopamine could be simultaneously used as a reducing agent for graphene oxide and as an adhesive, similar to the mortar in nacre, to crosslink the adjacent graphene. The resultant nacre-like graphene paper exhibited stable superhydrophobicity, self-cleaning, anti-corrosion, and remarkable mechanical properties underwater.Multifunctional integration is an inherent characteristic for biological materials with multiscale structures. Learning from nature is an effective approach for scientists and engineers to construct multifunctional materials. In nature, mollusks (abalone), mussels, and the lotus have evolved different and optimized solutions to survive. Here, bio-inspired multifunctional graphene composite paper was fabricated in situ through the fusion of the different biological solutions from nacre (brick-and-mortar structure), mussel adhesive protein (adhesive property and reducing character), and the lotus leaf (self-cleaning effect). Owing to the special properties (self-polymerization, reduction, and adhesion), dopamine could be simultaneously used as a reducing agent for graphene oxide and as an adhesive, similar to the mortar in nacre, to crosslink the adjacent graphene. The resultant nacre-like graphene paper exhibited stable superhydrophobicity, self-cleaning, anti-corrosion, and remarkable mechanical properties underwater. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr33632h

Effect of ageing time on mechanical properties of plasticized poly(hydroxybutyrate) (PHB)

NASA Astrophysics Data System (ADS)

Farris, Giuseppe; Cinelli, Patrizia; Anguillesi, Irene; Salvadori, Sara; Coltelli, Maria-Beatrice; Lazzeri, Andrea

2014-05-01

Polyhydroxybutyrate (PHB) based materials were prepared by melt extrusion by using different plasticizers, such as poly(ethylene glycol)s (PEG)s having different molecular weight (400, 1500 and 4000). The plasticizers content was varied in the range 10-20% by weight versus the PHB polymeric matrix. The variation of tensile properties of the different samples was monitored as a function of time of ageing to study the stability of the material. The elastic modulus and tensile strength increased as a function of time, whereas the strain at break decreased. The experimental results were explained by considering both the demixing of the plasticizers and the occurring of secondary crystallization. Moreover the variation in mechanical properties was correlated to the structure and concentration of the different plasticizers employed.

Developing a Sealing Material: Effect of Epoxy Modification on Specific Physical and Mechanical Properties

PubMed Central

Schoberleitner, Christoph; Archodoulaki, Vasiliki-Maria; Koch, Thomas; Lüftl, Sigrid; Werderitsch, Markus; Kuschnig, Gerhard

2013-01-01

To develop a matched sealing material for socket rehabilitation of grey cast iron pipes, an epoxy resin is modified by the addition of different components to improve the flexibility. Three different modifications are made by adding ethylene-propylene diene monomer (EPDM) rubber powder, reactive liquid polymer (ATBN) and epoxidized modifier. In this paper the effect of the modification method as well as the influence of absorption of water on the mechanical and physical properties are analyzed in terms of: tensile strength, modulus of elasticity, adhesion performance, pressure resistance, glass transition temperature and water content. A comparison with neat epoxy shows for all materials that the modulus of elasticity and strength decrease. Unlike other tested modification methods, the modification with rubber powder did not enhance the flexibility. All materials absorb water and a plasticization effect arises with further changes of mechanical and physical properties. The application of the sealant on the grey cast iron leads to a reduction of the strain at break (in comparison to the common tensile test of the pure materials) and has to be evaluated. The main requirement of pressure resistance up to 1 MPa was tested on two chosen materials. Both materials fulfill this requirement. PMID:28788404

Developing a Sealing Material: Effect of Epoxy Modification on Specific Physical and Mechanical Properties.

PubMed

Schoberleitner, Christoph; Archodoulaki, Vasiliki-Maria; Koch, Thomas; Lüftl, Sigrid; Werderitsch, Markus; Kuschnig, Gerhard

2013-11-27

To develop a matched sealing material for socket rehabilitation of grey cast iron pipes, an epoxy resin is modified by the addition of different components to improve the flexibility. Three different modifications are made by adding ethylene-propylene diene monomer (EPDM) rubber powder, reactive liquid polymer (ATBN) and epoxidized modifier. In this paper the effect of the modification method as well as the influence of absorption of water on the mechanical and physical properties are analyzed in terms of: tensile strength, modulus of elasticity, adhesion performance, pressure resistance, glass transition temperature and water content. A comparison with neat epoxy shows for all materials that the modulus of elasticity and strength decrease. Unlike other tested modification methods, the modification with rubber powder did not enhance the flexibility. All materials absorb water and a plasticization effect arises with further changes of mechanical and physical properties. The application of the sealant on the grey cast iron leads to a reduction of the strain at break (in comparison to the common tensile test of the pure materials) and has to be evaluated. The main requirement of pressure resistance up to 1 MPa was tested on two chosen materials. Both materials fulfill this requirement.

A physical interpretation of softening of pressure-sensitive and anisotropic materials

NASA Astrophysics Data System (ADS)

Hu, W.; Wang, Z. R.

2010-07-01

Several new dynamic models are proposed to explain the mechanical behaviour of softening of pressure-sensitive and anisotropic materials at a macroscopic level. If a pressure-sensitive material is loaded by a force and a variable pressure or an anisotropic material is subjected to a load with a changeable loading direction relative to the material frame, their stress-strain relationships become more complicated. Mechanical behaviours of these stress-strain relationships have to cover the feature concerning the change of pressure or loading direction, i.e. mechanical properties of pressure-sensitive material corresponding to different pressure state or anisotropic material relating to different loading direction will play an important role in deciding their stress-strain relationships. Such shift of material properties due to the variable pressure or loading history may significantly expand the traditional concept of the stability of material deformation, and the second order of plastic work being negative may be a response of stable plastic deformation, which is commonly called softening.

Development of a Novel Method for Determination of Residual Stresses in a Friction Stir Weld

NASA Technical Reports Server (NTRS)

Reynolds, Anthony P.

2001-01-01

Material constitutive properties, which describe the mechanical behavior of a material under loading, are vital to the design and implementation of engineering materials. For homogeneous materials, the standard process for determining these properties is the tensile test, which is used to measure the material stress-strain response. However, a majority of the applications for engineering materials involve the use of heterogeneous materials and structures (i.e. alloys, welded components) that exhibit heterogeneity on a global or local level. Regardless of the scale of heterogeneity, the overall response of the material or structure is dependent on the response of each of the constituents. Therefore, in order to produce materials and structures that perform in the best possible manner, the properties of the constituents that make up the heterogeneous material must be thoroughly examined. When materials exhibit heterogeneity on a local level, such as in alloys or particle/matrix composites, they are often treated as statistically homogenous and the resulting 'effective' properties may be determined through homogenization techniques. In the case of globally heterogeneous materials, such as weldments, the standard tensile test provides the global response but no information on what is Occurring locally within the different constituents. This information is necessary to improve the material processing as well as the end product.

The effect of high-pressure torsion on the microstructure and properties of magnesium

NASA Astrophysics Data System (ADS)

Figueiredo, Roberto B.; Sabbaghianrad, Shima; Langdon, Terence G.

2017-05-01

High-pressure torsion provides the opportunity to introduce significant plastic strain at room temperature in magnesium and its alloys. It is now established that this processing operation produces ultrafine-grained structures and changes the properties of these materials. The present paper shows that the mechanism of grain refinement differs from f.c.c. and b.c.c. materials. It is shown that fine grains are formed at the grain boundaries of coarse grains and gradually consume the whole structure. Also, the processed material exhibits unusual mechanical properties due to the activation of grain boundary sliding at room temperature.

Nuclear and Physical Properties of Dielectrics under Neutron Irradiation in Fast (BN-600) and Fusion (DEMO-S) Reactors

NASA Astrophysics Data System (ADS)

Blokhin, D. A.; Chernov, V. M.; Blokhin, A. I.

2017-12-01

Nuclear and physical properties (activation and transmutation of elements) of BN and Al2O3 dielectric materials subjected to neutron irradiation for up to 5 years in Russian fast (BN-600) and fusion (DEMO-S) reactors were calculated using the ACDAM-2.0 software complex for different post-irradiation cooling times (up to 10 years). Analytical relations were derived for the calculated quantities. The results may be used in the analysis of properties of irradiated dielectric materials and may help establish the rules for safe handling of these materials.

Statistical distribution of mechanical properties for three graphite-epoxy material systems

NASA Technical Reports Server (NTRS)

Reese, C.; Sorem, J., Jr.

1981-01-01

Graphite-epoxy composites are playing an increasing role as viable alternative materials in structural applications necessitating thorough investigation into the predictability and reproducibility of their material strength properties. This investigation was concerned with tension, compression, and short beam shear coupon testing of large samples from three different material suppliers to determine their statistical strength behavior. Statistical results indicate that a two Parameter Weibull distribution model provides better overall characterization of material behavior for the graphite-epoxy systems tested than does the standard Normal distribution model that is employed for most design work. While either a Weibull or Normal distribution model provides adequate predictions for average strength values, the Weibull model provides better characterization in the lower tail region where the predictions are of maximum design interest. The two sets of the same material were found to have essentially the same material properties, and indicate that repeatability can be achieved.

Effect of manufacturing and experimental conditions on the mechanical and surface properties of silicone elastomer scaffolds used in endothelial mechanobiological studies.

PubMed

Campeau, Marc-Antoine; Lortie, Audrey; Tremblay, Pierrick; Béliveau, Marc-Olivier; Dubé, Dominic; Langelier, Ève; Rouleau, Léonie

2017-07-14

Mechanobiological studies allow the characterization of cell response to mechanical stresses. Cells need to be supported by a material with properties similar to the physiological environment. Silicone elastomers have been used to produce various in vitro scaffolds of different geometries for endothelial cell studies given its relevant mechanical, optical and surface properties. However, obtaining defined and repeatable properties is a challenge as depending on the different manufacturing and processing steps, mechanical and surface properties may vary significantly between research groups. The impact of different manufacturing and processing methods on the mechanical and surface properties was assessed by measuring the Young's modulus and the contact angle. Silicone samples were produced using different curing temperatures and processed with different sterilization techniques and hydrophilization conditions. Different curing temperatures were used to obtain materials of different stiffness with a chosen silicone elastomer, i.e. Sylgard 184 ® . Sterilization by boiling had a tendency to stiffen samples cured at lower temperatures whereas UV and ethanol did not alter the material properties. Hydrophilization using sulphuric acid allowed to decrease surface hydrophobicity, however this effect was lost over time as hydrophobic recovery occurred. Extended contact with water maintained decreased hydrophobicity up to 7 days. Mechanobiological studies require complete cell coverage of the scaffolds used prior to mechanical stresses exposure. Different concentrations of fibronectin and collagen were used to coat the scaffolds and cell seeding density was varied to optimize cell coverage. This study highlights the potential bias introduced by manufacturing and processing conditions needed in the preparation of scaffolds used in mechanobiological studies involving endothelial cells. As manufacturing, processing and cell culture conditions are known to influence cell adhesion and function, they should be more thoroughly assessed by research groups that perform such mechanobiological studies using silicone.

Tuning Material Properties of Oxides and Nitrides by Substrate Biasing during Plasma-Enhanced Atomic Layer Deposition on Planar and 3D Substrate Topographies.

PubMed

Faraz, Tahsin; Knoops, Harm C M; Verheijen, Marcel A; van Helvoirt, Cristian A A; Karwal, Saurabh; Sharma, Akhil; Beladiya, Vivek; Szeghalmi, Adriana; Hausmann, Dennis M; Henri, Jon; Creatore, Mariadriana; Kessels, Wilhelmus M M

2018-04-18

Oxide and nitride thin-films of Ti, Hf, and Si serve numerous applications owing to the diverse range of their material properties. It is therefore imperative to have proper control over these properties during materials processing. Ion-surface interactions during plasma processing techniques can influence the properties of a growing film. In this work, we investigated the effects of controlling ion characteristics (energy, dose) on the properties of the aforementioned materials during plasma-enhanced atomic layer deposition (PEALD) on planar and 3D substrate topographies. We used a 200 mm remote PEALD system equipped with substrate biasing to control the energy and dose of ions by varying the magnitude and duration of the applied bias, respectively, during plasma exposure. Implementing substrate biasing in these forms enhanced PEALD process capability by providing two additional parameters for tuning a wide range of material properties. Below the regimes of ion-induced degradation, enhancing ion energies with substrate biasing during PEALD increased the refractive index and mass density of TiO x and HfO x and enabled control over their crystalline properties. PEALD of these oxides with substrate biasing at 150 °C led to the formation of crystalline material at the low temperature, which would otherwise yield amorphous films for deposition without biasing. Enhanced ion energies drastically reduced the resistivity of conductive TiN x and HfN x films. Furthermore, biasing during PEALD enabled the residual stress of these materials to be altered from tensile to compressive. The properties of SiO x were slightly improved whereas those of SiN x were degraded as a function of substrate biasing. PEALD on 3D trench nanostructures with biasing induced differing film properties at different regions of the 3D substrate. On the basis of the results presented herein, prospects afforded by the implementation of this technique during PEALD, such as enabling new routes for topographically selective deposition on 3D substrates, are discussed.

Quantifying the risks of solid aerosol geoengineering: the role of fundamental material properties

NASA Astrophysics Data System (ADS)

Dykema, J. A.; Keutsch, F. N.; Keith, D.

2017-12-01

Solid aerosols have been considered as an alternative to sulfate aerosols for solar geoengineering due to their optical and chemical properties, which lead to different and possibly more attractive risk profiles. Solid aerosols can achieve higher solar scattering efficiency due to their higher refractive index, and in some cases may also be less effective absorbers of thermal infrared radiation. The optical properties of solid aerosols are however sensitive functions of the detailed physical properties of solid materials in question. The relevant details include the exact crystalline structure of the aerosols, the physical size of the particles, and interactions with background stratospheric molecular and particulate constituents. In this work, we examine the impact of these detailed physical properties on the radiative properties of calcite (CaCO3) solid aerosols. We examine how crystal morphology, size, chemical reactions, and interaction with background stratospheric aerosol may alter the scattering and absorption properties of calcite aerosols for solar and thermal infrared radiation. For example, in small particles, crystal lattice vibrations associated with the particle surface may lead to substantially different infrared absorption properties than bulk materials. We examine the wavelength dependence of absorption by the particles, which may lead to altered patterns of stratospheric radiative heating and equilibrium temperatures. Such temperature changes can lead to dynamical changes, with consequences for both stratospheric composition and tropospheric climate. We identify important uncertainties in the current state of understanding, investigate risks associated with these uncertainties, and survey potential approaches to quantitatively improving our knowledge of the relevant material properties.

Wearable energy sources based on 2D materials.

PubMed

Yi, Fang; Ren, Huaying; Shan, Jingyuan; Sun, Xiao; Wei, Di; Liu, Zhongfan

2018-05-08

Wearable energy sources are in urgent demand due to the rapid development of wearable electronics. Besides flexibility and ultrathin thickness, emerging 2D materials present certain extraordinary properties that surpass the properties of conventional materials, which make them advantageous for high-performance wearable energy sources. Here, we provide a comprehensive review of recent advances in 2D material based wearable energy sources including wearable batteries, supercapacitors, and different types of energy harvesters. The crucial roles of 2D materials in the wearable energy sources are highlighted. Based on the current progress, the existing challenges and future prospects are outlined and discussed.

Structure - Property Relationships of Furanyl Thermosetting Polymer Materials Derived from Biobased Feedstocks

NASA Astrophysics Data System (ADS)

Hu, Fengshuo

Biobased thermosetting polymers have drawn significant attention due to their potential positive economic and ecological impacts. New materials should mimic the rigid, phenylic structures of incumbent petroleum-based thermosetting monomers and possess superior thermal and mechanical properties. Furans and triglycerides derived from cellulose, hemicellulose and plant oils are promising candidates for preparing such thermosetting materials. In this work, furanyl diepoxies, diamines and di-vinyl esters were synthesized using biobased furanyl materials, and their thermal and mechanical properties were investigated using multiple techniques. The structure versus property relationship showed that, compared with the prepared phenylic analogues, biobased furanyl thermosetting materials possess improved glassy storage modulus (E '), advanced fracture toughness, superior high-temperature char yield and comparable glass transition temperature (Tg) properties. An additive molar function analysis of the furanyl building block to the physical properties, such as Tg and density, of thermosetting polymers was performed. The molar glass transition function value (Yg) and molar volume increment value (Va,i) of the furanyl building block were obtained. Biobased epoxidized soybean oil (ESO) was modified using different fatty acids at varying molar ratios, and these prepared materials dramatically improved the critical strain energy release rate (G1c) and the critical stress intensity factor (K1c) values of commercial phenylic epoxy resins, without impairing their Tg and E ' properties. Overall, it was demonstrated that biobased furans and triglycerides possess promising potential for use in preparing high-performance thermosetting materials, and the established methodologies in this work can be utilized to direct the preparation of thermosetting materials with thermal and mechanical properties desired for practical applications.

EXPERIMENTAL MODELLING OF AORTIC ANEURYSMS

PubMed Central

Doyle, Barry J; Corbett, Timothy J; Cloonan, Aidan J; O’Donnell, Michael R; Walsh, Michael T; Vorp, David A; McGloughlin, Timothy M

2009-01-01

A range of silicone rubbers were created based on existing commercially available materials. These silicones were designed to be visually different from one another and have distinct material properties, in particular, ultimate tensile strengths and tear strengths. In total, eleven silicone rubbers were manufactured, with the materials designed to have a range of increasing tensile strengths from approximately 2-4MPa, and increasing tear strengths from approximately 0.45-0.7N/mm. The variations in silicones were detected using a standard colour analysis technique. Calibration curves were then created relating colour intensity to individual material properties. All eleven materials were characterised and a 1st order Ogden strain energy function applied. Material coefficients were determined and examined for effectiveness. Six idealised abdominal aortic aneurysm models were also created using the two base materials of the study, with a further model created using a new mixing technique to create a rubber model with randomly assigned material properties. These models were then examined using videoextensometry and compared to numerical results. Colour analysis revealed a statistically significant linear relationship (p<0.0009) with both tensile strength and tear strength, allowing material strength to be determined using a non-destructive experimental technique. The effectiveness of this technique was assessed by comparing predicted material properties to experimentally measured methods, with good agreement in the results. Videoextensometry and numerical modelling revealed minor percentage differences, with all results achieving significance (p<0.0009). This study has successfully designed and developed a range of silicone rubbers that have unique colour intensities and material strengths. Strengths can be readily determined using a non-destructive analysis technique with proven effectiveness. These silicones may further aid towards an improved understanding of the biomechanical behaviour of aneurysms using experimental techniques. PMID:19595622

Effect of roll compaction on granule size distribution of microcrystalline cellulose–mannitol mixtures: computational intelligence modeling and parametric analysis

PubMed Central

Kazemi, Pezhman; Khalid, Mohammad Hassan; Pérez Gago, Ana; Kleinebudde, Peter; Jachowicz, Renata; Szlęk, Jakub; Mendyk, Aleksander

2017-01-01

Dry granulation using roll compaction is a typical unit operation for producing solid dosage forms in the pharmaceutical industry. Dry granulation is commonly used if the powder mixture is sensitive to heat and moisture and has poor flow properties. The output of roll compaction is compacted ribbons that exhibit different properties based on the adjusted process parameters. These ribbons are then milled into granules and finally compressed into tablets. The properties of the ribbons directly affect the granule size distribution (GSD) and the quality of final products; thus, it is imperative to study the effect of roll compaction process parameters on GSD. The understanding of how the roll compactor process parameters and material properties interact with each other will allow accurate control of the process, leading to the implementation of quality by design practices. Computational intelligence (CI) methods have a great potential for being used within the scope of quality by design approach. The main objective of this study was to show how the computational intelligence techniques can be useful to predict the GSD by using different process conditions of roll compaction and material properties. Different techniques such as multiple linear regression, artificial neural networks, random forest, Cubist and k-nearest neighbors algorithm assisted by sevenfold cross-validation were used to present generalized models for the prediction of GSD based on roll compaction process setting and material properties. The normalized root-mean-squared error and the coefficient of determination (R2) were used for model assessment. The best fit was obtained by Cubist model (normalized root-mean-squared error =3.22%, R2=0.95). Based on the results, it was confirmed that the material properties (true density) followed by compaction force have the most significant effect on GSD. PMID:28176905

Effect of roll compaction on granule size distribution of microcrystalline cellulose-mannitol mixtures: computational intelligence modeling and parametric analysis.

PubMed

Kazemi, Pezhman; Khalid, Mohammad Hassan; Pérez Gago, Ana; Kleinebudde, Peter; Jachowicz, Renata; Szlęk, Jakub; Mendyk, Aleksander

2017-01-01

Dry granulation using roll compaction is a typical unit operation for producing solid dosage forms in the pharmaceutical industry. Dry granulation is commonly used if the powder mixture is sensitive to heat and moisture and has poor flow properties. The output of roll compaction is compacted ribbons that exhibit different properties based on the adjusted process parameters. These ribbons are then milled into granules and finally compressed into tablets. The properties of the ribbons directly affect the granule size distribution (GSD) and the quality of final products; thus, it is imperative to study the effect of roll compaction process parameters on GSD. The understanding of how the roll compactor process parameters and material properties interact with each other will allow accurate control of the process, leading to the implementation of quality by design practices. Computational intelligence (CI) methods have a great potential for being used within the scope of quality by design approach. The main objective of this study was to show how the computational intelligence techniques can be useful to predict the GSD by using different process conditions of roll compaction and material properties. Different techniques such as multiple linear regression, artificial neural networks, random forest, Cubist and k-nearest neighbors algorithm assisted by sevenfold cross-validation were used to present generalized models for the prediction of GSD based on roll compaction process setting and material properties. The normalized root-mean-squared error and the coefficient of determination ( R 2 ) were used for model assessment. The best fit was obtained by Cubist model (normalized root-mean-squared error =3.22%, R 2 =0.95). Based on the results, it was confirmed that the material properties (true density) followed by compaction force have the most significant effect on GSD.

Use of updated material properties in parametric optimization of spaceborne mirrors

NASA Astrophysics Data System (ADS)

Hull, Tony; Westerhoff, Thomas; Weidmann, Guenter; Kirchhoff, Rule

2016-07-01

Spaceborne sensor mirrors need to be both structurally efficient and to maintain figure through thermal transients. Both properties can be represented in a plot showing structural efficiency on one axis and thermal transient resilience on the other. For material selection, engineers have effectively used such charts. However in some cases thermal attributes have improved considerably. Using contemporary values, this comparison chart looks differently. We will discuss how lines of equal merit may be formulated differently depending on the orbit of the mission.

Hydrogels as a Replacement Material for Damaged Articular Hyaline Cartilage

PubMed Central

Beddoes, Charlotte M.; Whitehouse, Michael R.; Briscoe, Wuge H.; Su, Bo

2016-01-01

Hyaline cartilage is a strong durable material that lubricates joint movement. Due to its avascular structure, cartilage has a poor self-healing ability, thus, a challenge in joint recovery. When severely damaged, cartilage may need to be replaced. However, currently we are unable to replicate the hyaline cartilage, and as such, alternative materials with considerably different properties are used. This results in undesirable side effects, including inadequate lubrication, wear debris, wear of the opposing articular cartilage, and weakening of the surrounding tissue. With the number of surgeries for cartilage repair increasing, a need for materials that can better mimic cartilage, and support the surrounding material in its typical function, is becoming evident. Here, we present a brief overview of the structure and properties of the hyaline cartilage and the current methods for cartilage repair. We then highlight some of the alternative materials under development as potential methods of repair; this is followed by an overview of the development of tough hydrogels. In particular, double network (DN) hydrogels are a promising replacement material, with continually improving physical properties. These hydrogels are coming closer to replicating the strength and toughness of the hyaline cartilage, while offering excellent lubrication. We conclude by highlighting several different methods of integrating replacement materials with the native joint to ensure stability and optimal behaviour. PMID:28773566

Hydrogels as a Replacement Material for Damaged Articular Hyaline Cartilage.

PubMed

Beddoes, Charlotte M; Whitehouse, Michael R; Briscoe, Wuge H; Su, Bo

2016-06-03

Hyaline cartilage is a strong durable material that lubricates joint movement. Due to its avascular structure, cartilage has a poor self-healing ability, thus, a challenge in joint recovery. When severely damaged, cartilage may need to be replaced. However, currently we are unable to replicate the hyaline cartilage, and as such, alternative materials with considerably different properties are used. This results in undesirable side effects, including inadequate lubrication, wear debris, wear of the opposing articular cartilage, and weakening of the surrounding tissue. With the number of surgeries for cartilage repair increasing, a need for materials that can better mimic cartilage, and support the surrounding material in its typical function, is becoming evident. Here, we present a brief overview of the structure and properties of the hyaline cartilage and the current methods for cartilage repair. We then highlight some of the alternative materials under development as potential methods of repair; this is followed by an overview of the development of tough hydrogels. In particular, double network (DN) hydrogels are a promising replacement material, with continually improving physical properties. These hydrogels are coming closer to replicating the strength and toughness of the hyaline cartilage, while offering excellent lubrication. We conclude by highlighting several different methods of integrating replacement materials with the native joint to ensure stability and optimal behaviour.

Construction patterns of birds’ nests provide insight into nest-building behaviours

PubMed Central

Goodman, Adrian M.

2017-01-01

Previous studies have suggested that birds and mammals select materials needed for nest building based on their thermal or structural properties, although the amounts or properties of the materials used have been recorded for only a very small number of species. Some of the behaviours underlying the construction of nests can be indirectly determined by careful deconstruction of the structure and measurement of the biomechanical properties of the materials used. Here we examined this idea in an investigation of Bullfinch (Pyrrhula pyrrhula) nests as a model for open-nesting songbird species that construct a “twig” nest, and tested the hypothesis that materials in different parts of nests serve different functions. The quantities of materials present in the nest base, sides and cup were recorded before structural analysis. Structural analysis showed that the base of the outer nests were composed of significantly thicker, stronger and more rigid materials compared to the side walls, which in turn were significantly thicker, stronger and more rigid than materials used in the cup. These results suggest that the placement of particular materials in nests may not be random, but further work is required to determine if the final structure of a nest accurately reflects the construction process. PMID:28265501

Flexible barrier materials for protection against electromagnetic fields and their characterization

NASA Astrophysics Data System (ADS)

Jaroszewski, Maciej

2015-10-01

Composite materials for electromagnetic shielding can be manufactured as textiles using conductive yarns and textiles with conductivity obtained by various finishing processes on textile surfaces. The EM shielding effectiveness of fabrics are improved by lowering its conductivity using different methods and materials. An alternative is the usage of new light shielding materials in the form of metallized nonwoven fabrics or textiles. Their advantages are: a general availability on the market, a low price, good mechanical properties (strength, elasticity) and resistance to the environmental conditions. The composite anisotropic materials with a sandwich structure constituting of materials with different spatial orientations of fibers allow one to achieve relatively high and constant values of the shielding effectiveness which, together with the materials' mechanical properties, leads to a wide range of applicability in various disciplines of modern technology. This article is devoted to innovative flexible materials shielding electromagnetic field. The results of the PEM shielding effectiveness obtained for the polypropylene (PP) nonwoven fabrics metallized by pulsed magnetron sputtering are presented.

Methods of photoelectrode characterization with high spatial and temporal resolution

DOE PAGES

Esposito, Daniel V.; Baxter, Jason B.; John, Jimmy; ...

2015-06-19

Here, materials and photoelectrode architectures that are highly efficient, extremely stable, and made from low cost materials are required for commercially viable photoelectrochemical (PEC) water-splitting technology. A key challenge is the heterogeneous nature of real-world materials, which often possess spatial variation in their crystal structure, morphology, and/or composition at the nano-, micro-, or macro-scale. Different structures and compositions can have vastly different properties and can therefore strongly influence the overall performance of the photoelectrode through complex structure–property relationships. A complete understanding of photoelectrode materials would also involve elucidation of processes such as carrier collection and electrochemical charge transfer that occurmore » at very fast time scales. We present herein an overview of a broad suite of experimental and computational tools that can be used to define the structure–property relationships of photoelectrode materials at small dimensions and on fast time scales. A major focus is on in situ scanning-probe measurement (SPM) techniques that possess the ability to measure differences in optical, electronic, catalytic, and physical properties with nano- or micro-scale spatial resolution. In situ ultrafast spectroscopic techniques, used to probe carrier dynamics involved with processes such as carrier generation, recombination, and interfacial charge transport, are also discussed. Complementing all of these experimental techniques are computational atomistic modeling tools, which can be invaluable for interpreting experimental results, aiding in materials discovery, and interrogating PEC processes at length and time scales not currently accessible by experiment. In addition to reviewing the basic capabilities of these experimental and computational techniques, we highlight key opportunities and limitations of applying these tools for the development of PEC materials.« less

Analytical, numerical, and experimental investigations on effective mechanical properties and performances of carbon nanotubes and nanotube based nanocomposites with novel three dimensional nanostructures

NASA Astrophysics Data System (ADS)

Askari, Davood

The theoretical objectives and accomplishment of this work are the analytical and numerical investigation of material properties and mechanical behavior of carbon nanotubes (CNTs) and nanotube nanocomposites when they are subjected to various loading conditions. First, the finite element method is employed to investigate numerically the effective Young's modulus and Poisson's ratio of a single-walled CNT. Next, the effects of chirality on the effective Young's modulus and Poisson's ratio are investigated and then variations of their effective coefficient of thermal expansions and effective thermal conductivities are studied for CNTs with different structural configurations. To study the influence of small vacancy defects on mechanical properties of CNTs, finite element analyses are performed and the behavior of CNTs with various structural configurations having different types of vacancy defects is studied. It is frequently reported that nano-materials are excellent candidates as reinforcements in nanocomposites to change or enhance material properties of polymers and their nanocomposites. Second, the inclusion of nano-materials can considerably improve electrical, thermal, and mechanical properties of the bonding agent, i.e., resin. Note that, materials atomic and molecular level do not usually show isotropic behaviour, rather they have orthotropic properties. Therefore, two-phase and three-phase cylindrically orthotropic composite models consisting of different constituents with orthotropic properties are developed and introduced in this work to analytically predict the effective mechanical properties and mechanical behavior of such structures when they are subjected to various external loading conditions. To verify the analytically obtained exact solutions, finite element analyses of identical cylindrical structures are also performed and then results are compared with those obtained analytically, and excellent agreement is achieved. The third part of this dissertation investigates the growth of vertically aligned, long, and high density arrays of CNTs and novel 3-D carbon nanotube nano-forests. A Chemical vapor deposition technique is used to grow radially aligned CNTs on various types of fibrous materials such as silicon carbide, carbon, Kevlar, and glass fibers and clothes that can be used for the fabrication of multifunctional high performing laminated nanocomposite structures. Using the CNTs nano-forest clothes, nanocomposite samples are prepared and tested giving promising results for the improvement of mechanical properties and performance of composites structures.

Material platforms for spin-based photonic quantum technologies

NASA Astrophysics Data System (ADS)

Atatüre, Mete; Englund, Dirk; Vamivakas, Nick; Lee, Sang-Yun; Wrachtrup, Joerg

2018-05-01

A central goal in quantum optics and quantum information science is the development of quantum networks to generate entanglement between distributed quantum memories. Experimental progress relies on the quality and efficiency of the light-matter quantum interface connecting the quantum states of photons to internal states of quantum emitters. Quantum emitters in solids, which have properties resembling those of atoms and ions, offer an opportunity for realizing light-matter quantum interfaces in scalable and compact hardware. These quantum emitters require a material platform that enables stable spin and optical properties, as well as a robust manufacturing of quantum photonic circuits. Because no emitter system is yet perfect and different applications may require different properties, several light-matter quantum interfaces are being developed in various platforms. This Review highlights the progress in three leading material platforms: diamond, silicon carbide and atomically thin semiconductors.

Damage Tolerance Enhancement of Carbon Fiber Reinforced Polymer Composites by Nanoreinforcement of Matrix

NASA Astrophysics Data System (ADS)

Fenner, Joel Stewart

Nanocomposites are a relatively new class of materials which incorporate exotic, engineered nanoparticles to achieve superior material properties. Because of their extremely small size and well-ordered structure, many nanoparticles possess properties that exceed those offered by a wide range of other known materials, making them attractive candidates for novel materials engineering development. Their small size is also an impediment to their practical use, as they typically cannot be employed by themselves to realize those properties in large structures. Furthermore, nanoparticles typically possess strong self-affinity, rendering them difficult to disperse uniformly into a composite. However, contemporary research has shown that, if well-dispersed, nanoparticles have great capacity to improve the mechanical properties of composites, especially damage tolerance, in the form of fracture toughness, fatigue life, and impact damage mitigation. This research focuses on the development, manufacturing, and testing of hybrid micro/nanocomposites comprised of woven carbon fibers with a carbon nanotube reinforced epoxy matrix. Material processing consisted of dispersant-and-sonication based methods to disperse nanotubes into the matrix, and a vacuum-assisted wet lay-up process to prepare the hybrid composite laminates. Various damage tolerance properties of the hybrid composite were examined, including static strength, fracture toughness, fatigue life, fatigue crack growth rate, and impact damage behavior, and compared with similarly-processed reference material produced without nanoreinforcement. Significant improvements were obtained in interlaminar shear strength (15%), Mode-I fracture toughness (180%), shear fatigue life (order of magnitude), Mode-I fatigue crack growth rate (factor of 2), and effective impact damage toughness (40%). Observations by optical microscopy, scanning electron microscopy, and ultrasonic imaging showed significant differences in failure behavior and fracture morphology between the two materials, related to the differences in properties. Altogether these results provided a means for proposing an explanation of the mechanism of reinforcement (and damage tolerance enhancement) provided by carbon nanotubes in hybrid composite materials.

Rehabilitation of adobe buildings. Understanding different materials from Portugal

NASA Astrophysics Data System (ADS)

Costa, Cristiana; Rocha, Fernando; Velosa, Ana

2016-04-01

Earth construction is the oldest building material known, with documented cases of the use of earth bricks since Mesopotamia around 10 000 BC (Heathcote, 1995). The earth construction exists throughout the majority of the world in different cultures, and for some countries, nowadays it continues to be the main process of construction (Vega et al, 2011). Around 30% of the world's population lives in buildings made of earth materials. Earthen construction is an environmentally friendly technique with a social and cultural contribution; this advantage is increased when this type of construction is applied in developing countries where the material costs counterbalance with labour costs, and where other materials and techniques cannot be available (Ciancio et al, 2013). Studies of materials characterization are required in order to understand the composition and specific properties of the earth buildings, their heterogeneity and their degradation mechanisms. Some adobes from different buildings, ages and regions of Portugal were collected in order to characterize them (mineralogically, chemically and physically). It was possible to understand the composition of these materials and their differences. Main minerals are quartz, feldspars, calcite and phyllosilicates (mica and kaolinite). The mechanical behaviour of these materials isn't the best, but it is possible to improve it with some simple and cheap natural additives (kaolinitic soils). The characterization of these materials allows us to understand the differences between the materials from the different regions (controlled by locally available raw materials). Understanding these materials, and their properties, it is possible to formulate new ones for repair, conservation and rehabilitation works. The adobe bricks are an alternative of kiln baked bricks which has several advantages and one of the most important is that these materials are recyclable. Adobes are an excellent option for building rehabilitation, if composition is optimised.

Influence of Powder Outgassing Conditions on the Chemical, Microstructural, and Mechanical Properties of a 14 wt% Cr Ferritic ODS Steel

NASA Astrophysics Data System (ADS)

Sornin, D.; Giroux, P.-F.; Rigal, E.; Fabregue, D.; Soulas, R.; Hamon, D.

2017-11-01

Oxide dispersion-strengthened ferritic stainless steels are foreseen as fuel cladding tube materials for the new generation of sodium fast nuclear reactors. Those materials, which exhibit remarkable creep properties at high temperature, are reinforced by a dense precipitation of nanometric oxides. This precipitation is obtained by mechanical alloying of a powder and subsequent consolidation. Before consolidation, to obtain a fully dense material, the powder is vacuumed to outgas trapped gases and species adsorbed at the surface of the powder particles. This operation is commonly done at moderate to high temperature to evacuate as much as possible volatile species. This paper focuses on the influence of outgassing conditions on some properties of the further consolidated materials. Chemical composition and microstructural characterization of different materials obtained from various outgassing cycles are compared. Finally, impact toughness of those materials is evaluated by using Charpy testing. This study shows a significant influence of the outgassing conditions on the mechanical properties of the consolidated material. However, microstructure and oxygen contents seem poorly impacted by the various outgassing conditions.

Electrical and absorption properties of fresh cassava tubers and cassava starch

NASA Astrophysics Data System (ADS)

Harnsoongnoen, S.; Siritaratiwat, A.

2015-09-01

The objective of this study was to analyze the electrical and absorption properties of fresh cassava tubers and cassava starch at various frequencies using electric impedance spectroscopy and near-infrared spectroscopy, as well as determine the classification of the electrical parameters of both materials using the principle component analysis (PCA) method. All samples were measured at room temperature. The electrical and absorption parameters consisted of dielectric constant, dissipation factor, parallel capacitance, resistance, reactance, impedance and absorbance. It was found that the electrical and absorption properties of fresh cassava tubers and cassava starch were a function of frequency, and there were significant differences between the materials. The dielectric constant, parallel capacitance, resistance and impedance of fresh cassava tubers and cassava starch had similar dramatic decreases with increasing frequency. However, the reactance of both materials increased with an increasing frequency. The electrical parameters of both materials could be classified into two groups. Moreover, the dissipation factor and phase of impedance were the parameters that could be used in the separation of both materials. According to the absorbance patterns of the fresh cassava tubers and cassava starch, there were significant differences.

Ballistic Impact Testing of Aluminum 2024 and Titanium 6Al-4V for Material Model Development

NASA Technical Reports Server (NTRS)

Pereira, J. Michael; Revilock, Duane M.; Ruggeri, Charles R.; Emmerling, William C.; Altobelli, Donald J.

2012-01-01

An experimental program is underway to develop a consistent set of material property and impact test data, and failure analysis, for a variety of materials that can be used to develop improved impact failure and deformation models. Unique features of this set of data are that all material property information and impact test results are obtained using identical materials, the test methods and procedures are extensively documented and all of the raw data is available. This report describes ballistic impact testing which has been conducted on aluminum (Al) 2024 and titanium (Ti) 6Al-4vanadium (V) sheet and plate samples of different thicknesses and with different types of projectiles, one a regular cylinder and one with a more complex geometry incorporating features representative of a jet engine fan blade.

Effects of oxidation on the plasmonic properties of aluminum nanoclusters.

PubMed

Douglas-Gallardo, Oscar A; Soldano, Germán J; Mariscal, Marcelo M; Sánchez, Cristián Gabriel

2017-11-16

The scouting of alternative plasmonic materials able to enhance and extend the optical properties of noble metal nanostructures is on the rise. Aluminum is endowed with a set of interesting properties which turn it into an attractive plasmonic material. Here we present the optical and electronic features of different aluminum nanostructures stemming from a multilevel computational study. Molecular Dynamics (MD) simulations using a reactive force field (ReaxFF), carefully validated with Density Functional Theory (DFT), were employed to mimic the oxidation of icosahedral aluminum nanoclusters. Resulting structures with different oxidation degrees were then studied through the Time-Dependent Density Functional Tight Binding (TD-DFTB) method. A similar approach was used in aluminum nanoclusters with a disordered structure to study how the loss of crystallinity affects the optical properties. To the best of our knowledge, this is the first report that addresses this issue from the fully atomistic time-dependent approach by means of two different and powerful simulation tools able to describe quantum and physicochemical properties associated with nanostructured particles.

A novel composite material specifically developed for ultrasound bone phantoms: cortical, trabecular and skull

NASA Astrophysics Data System (ADS)

Wydra, A.; Maev, R. Gr

2013-11-01

In the various stages of developing diagnostic and therapeutic equipment, the use of phantoms can play a very important role in improving the process, help in implementation, testing and calibrations. Phantoms are especially useful in developing new applications and training new doctors in medical schools. However, devices that use different physical factors, such as MRI, Ultrasound, CT Scan, etc will require the phantom to be made of different physical properties. In this paper we introduce the properties of recently designed new materials for developing phantoms for ultrasonic human body investigation, which in today's market make up more than 30% in the world of phantoms. We developed a novel composite material which allows fabrication of various kinds of ultrasound bone phantoms to mimic most of the acoustical properties of human bones. In contrast to the ex vivo tissues, the proposed material can maintain the physical and acoustical properties unchanged for long periods of time; moreover, these properties can be custom designed and created to suit specific needs. As a result, we introduce three examples of ultrasound phantoms that we manufactured in our laboratory: cortical, trabecular and skull bone phantoms. The paper also presents the results of a comparison study between the acoustical and physical properties of actual human bones (reported in the referenced literatures) and the phantoms manufactured by us.

A novel composite material specifically developed for ultrasound bone phantoms: cortical, trabecular and skull.

PubMed

Wydra, A; Maev, R Gr

2013-11-21

In the various stages of developing diagnostic and therapeutic equipment, the use of phantoms can play a very important role in improving the process, help in implementation, testing and calibrations. Phantoms are especially useful in developing new applications and training new doctors in medical schools. However, devices that use different physical factors, such as MRI, Ultrasound, CT Scan, etc will require the phantom to be made of different physical properties. In this paper we introduce the properties of recently designed new materials for developing phantoms for ultrasonic human body investigation, which in today's market make up more than 30% in the world of phantoms. We developed a novel composite material which allows fabrication of various kinds of ultrasound bone phantoms to mimic most of the acoustical properties of human bones. In contrast to the ex vivo tissues, the proposed material can maintain the physical and acoustical properties unchanged for long periods of time; moreover, these properties can be custom designed and created to suit specific needs. As a result, we introduce three examples of ultrasound phantoms that we manufactured in our laboratory: cortical, trabecular and skull bone phantoms. The paper also presents the results of a comparison study between the acoustical and physical properties of actual human bones (reported in the referenced literatures) and the phantoms manufactured by us.

The effect of carbon chain length of starting materials on the formation of carbon dots and their optical properties

NASA Astrophysics Data System (ADS)

Pan, Xiaohua; Zhang, Yan; Sun, Xiaobo; Pan, Wei; Yu, Guifeng; Si, Shuxin; Wang, Jinping

2018-04-01

Carbon dots (CDs) have attracted increasing attention due to their high performances and potential applications in wide range of areas. However, their emission mechanism is not clear so far. In order to reveal more factors contributing to the emission of CDs, the effect of carbon chain length of starting materials on the formation of CDs and their optical properties was experimentally investigated in this work. In order to focus on the effect of carbon chain length, the starting materials with C, O, N in fully identical forms and only carbon chain lengths being different were selected for synthesizing CDs, including citric acid (CA) and adipic acid (AA) as carbon sources, and diamines with different carbon chain lengths (H2N(CH2)nNH2, n = 2, 4, 6) as nitrogen sources, as well as ethylenediamine (EDA) as nitrogen source and diacids with different carbon chain lengths (HOOC(CH2)nCOOH, n = 0, 2, 4, 6) as carbon sources. Therefore, the effect of carbon chain length of starting materials on the formation and optical properties of CDs can be systematically investigated by characterizing and comparing the structures and optical properties of as-prepared nine types of CDs. Moreover, the density of –NH2 on the surface of the CDs was quantitatively detected by a spectrophotometry so as to elucidate the relationship between the –NH2 related surface state and the optical properties.

Polytypism, polymorphism, and superconductivity in TaSe 2 –xTe x

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luo, Huixia; Xie, Weiwei; Tao, Jing

2015-03-03

Polymorphism in materials often leads to significantly different physical properties - the rutile and anatase polymorphs of TiO₂ are a prime example. Polytypism is a special type of polymorphism, occurring in layered materials when the geometry of a repeating structural layer is maintained but the layer stacking sequence of the overall crystal structure can be varied; SiC is an example of a material with many polytypes. Although polymorphs can have radically different physical properties, it is much rarer for polytypism to impact physical properties in a dramatic fashion. Here we study the effects of polytypism and polymorphism on the superconductivitymore » of TaSe₂, one of the archetypal members of the large family of layered dichalcogenides. We show that it is possible to access 2 stable polytypes and 2 stable polymorphs in the TaSe 2-xTe x solid solution, and find that the 3R polytype shows a superconducting transition temperature that is between 6 and 17 times higher than that of the much more commonly found 2H polytype. Thus, the reason for this dramatic change is not apparent, but we propose that it arises either from a remarkable dependence of T c on subtle differences in the characteristics of the single layers present, or from a surprising effect of the layer stacking sequence on electronic properties that instead are expected to be dominated by the properties of a single layer in materials of this kind.« less

Characterization of synthetic foam structures used to manufacture artificial vertebral trabecular bone.

PubMed

Fürst, David; Senck, Sascha; Hollensteiner, Marianne; Esterer, Benjamin; Augat, Peter; Eckstein, Felix; Schrempf, Andreas

2017-07-01

Artificial materials reflecting the mechanical properties of human bone are essential for valid and reliable implant testing and design. They also are of great benefit for realistic simulation of surgical procedures. The objective of this study was therefore to characterize two groups of self-developed synthetic foam structures by static compressive testing and by microcomputed tomography. Two mineral fillers and varying amounts of a blowing agent were used to create different expansion behavior of the synthetic open-cell foams. The resulting compressive and morphometric properties thus differed within and also slightly between both groups. Apart from the structural anisotropy, the compressive and morphometric properties of the synthetic foam materials were shown to mirror the respective characteristics of human vertebral trabecular bone in good approximation. In conclusion, the artificial materials created can be used to manufacture valid synthetic bones for surgical training. Further, they provide novel possibilities for studying the relationship between trabecular bone microstructure and biomechanical properties. Copyright © 2017 Elsevier B.V. All rights reserved.

Research on the Superheater Material Properties for USC Boiler with 700°C Steam Parameter

NASA Astrophysics Data System (ADS)

Chongbin, Wang; Xueyuan, Xu; Yufeng, Zhu; Yongqiang, Jin; Hui, Tong; Yu, Wang; Xiaoli, Lu

This paper discusses the materials' properties of superheater for 700°C USC boiler, including Sanicro25, HR6W, 617mod and 740H, and analyzes the range of applicable temperature of superheater made of different tubes, such as T91, T92, Super304H, TP310HCbN, Sanicro25, HR6W, 617Mod and 740H. In addition, some suggestions on the material selection have been proposed.

Molecular self-assembly approaches for supramolecular electronic and organic electronic devices

NASA Astrophysics Data System (ADS)

Yip, Hin-Lap

Molecular self-assembly represents an efficient bottom-up strategy to generate structurally well-defined aggregates of semiconducting pi-conjugated materials. The capability of tuning the chemical structures, intermolecular interactions and nanostructures through molecular engineering and novel materials processing renders it possible to tailor a large number of unprecedented properties such as charge transport, energy transfer and light harvesting. This approach does not only benefit traditional electronic devices based on bulk materials, but also generate a new research area so called "supramolecular electronics" in which electronic devices are built up with individual supramolecular nanostructures with size in the sub-hundred nanometers range. My work combined molecular self-assembly together with several novel materials processing techniques to control the nucleation and growth of organic semiconducting nanostructures from different type of pi-conjugated materials. By tailoring the interactions between the molecules using hydrogen bonds and pi-pi stacking, semiconducting nanoplatelets and nanowires with tunable sizes can be fabricated in solution. These supramolecular nanostructures were further patterned and aligned on solid substrates through printing and chemical templating methods. The capability to control the different hierarchies of organization on surface provides an important platform to study their structural-induced electronic properties. In addition to using molecular self-assembly to create different organic nanostructures, functional self-assembled monolayer (SAM) formed by spontaneous chemisorption on surfaces was used to tune the interfacial property in organic solar cells. Devices showed dramatically improved performance when appropriate SAMs were applied to optimize the contact property for efficiency charge collection.

Comparative study of the mechanical properties of different tungsten materials for fusion applications

NASA Astrophysics Data System (ADS)

Krimpalis, S.; Mergia, K.; Messoloras, S.; Dubinko, A.; Terentyev, D.; Triantou, K.; Reiser, J.; Pintsuk, G.

2017-12-01

The mechanical properties of tungsten produced in different forms before and after neutron irradiation are of considerable interest for their application in fusion devices such as ITER. In this work the mechanical properties and the microstructure of two tungsten (W) products with different microstructures are investigated using depth sensing nano/micro-indentation and transmission electron microscopy, respectively. Neutron irradiation of these materials for different doses, in the temperature range 600 °C-1200 °C, is underway within the EUROfusion project in order to progress our basic understanding of neutron irradiation effects on W. The hardness and elastic modulus are determined as a function of the penetration depth, loading/unloading rate, holding time at maximum load and the final surface treatment. The results are correlated with the microstructure as investigated by SEM and TEM measurements.

Comparison of physical properties of regenerated cellulose films fabricated with different cellulose feedstocks in ionic liquid.

PubMed

Pang, JinHui; Wu, Miao; Zhang, QiaoHui; Tan, Xin; Xu, Feng; Zhang, XueMing; Sun, RunCang

2015-05-05

With the serious "white pollution" resulted from the non-biodegradable plastic films, considerable attention has been directed toward the development of renewable and biodegradable cellulose-based film materials as substitutes of petroleum-derived materials. In this study, environmentally friendly cellulose films were successfully prepared using different celluloses (pine, cotton, bamboo, MCC) as raw materials and ionic liquid 1-ethyl-3-methylimidazolium acetate as a solvent. The SEM and AFM indicated that all cellulose films displayed a homogeneous and smooth surface. In addition, the FT-IR and XRD analysis showed the transition from cellulose I to II was occurred after the dissolution and regeneration process. Furthermore, the cellulose films prepared by cotton linters and pine possessed the most excellent thermal stability and mechanical properties, which were suggested by the highest onset temperature (285°C) and tensile stress (120 MPa), respectively. Their excellent properties of regenerated cellulose films are promising for applications in food packaging and medical materials. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effect of counterface material type and its topography on the tribological properties of polyimide composites

NASA Technical Reports Server (NTRS)

Fusaro, R. L.

1985-01-01

Graphite fiber reinforced polyimide composite pins were slid against seven different counterfaces to determine the effect of material type on the tribological properties of polymer composites. In addition, the effect of sliding a new pin on a pre-established transfer film was investigated. The results indicated that almost a five order of magnitude difference in composite wear rate can occur just by varying the counterface material. An attempt to make all surfaces as smooth as possible was made, but due to differences in material composition this was not possible and a range of surface roughnesses were obtained. The results indicate that the smoother the surface, the lower the composite wear rate; but that small protrusions (not discernible with arithmetic surface roughness measurements) can markedly increase wear rates. A pre-established transfer film improved both run in and steady state wear rates.

Ab initio theory of point defects in oxide materials: structure, properties, chemical reactivity

NASA Astrophysics Data System (ADS)

Pacchioni, Gianfranco

2000-05-01

Point defects play a fundamental role in determining the physical and chemical properties of inorganic materials. This holds not only for the bulk properties but also for the surface of oxides where several kinds of point defects exist and exhibit a rich and complex chemistry. A particularly important defect in oxides is the oxygen vacancy. Depending on the electronic structure of the material the nature of oxygen vacancies changes dramatically. In this article we provide a rationalization of the very different electronic structure of neutral and charged oxygen vacancies in SiO 2 and MgO, two oxide materials with completely different electronic structure (from very ionic, MgO, to largely covalent, SiO 2). We used methods of ab initio quantum chemistry, from density functional theory (DFT) to configuration interaction (CI), to determine the ground and excited state properties of these defects. The theoretical results are combined with recent spectroscopic measurements. A series of observable properties has been determined in this way: defect formation energies, hyperfine interactions in electron paramagnetic resonance (EPR) spectra of paramagnetic centers, optical spectra, surface chemical reactivity. The interplay between experimental and theoretical information allows one to unambiguously identify the structure of oxygen vacancies in these binary oxides and on their surfaces.

Control of Nanoscale Materials under the Toxic Substances Control Act

EPA Pesticide Factsheets

Many nanoscale materials are regarded as chemical substances, but they may have different properties than their larger counterparts. EPA is working to ensure that nanoscale materials are manufactured and used in ways that prevent risk to health.

Advanced Materials From Fungal Mycelium: Fabrication and Tuning of Physical Properties

NASA Astrophysics Data System (ADS)

Haneef, Muhammad; Ceseracciu, Luca; Canale, Claudio; Bayer, Ilker S.; Heredia-Guerrero, José A.; Athanassiou, Athanassia

2017-01-01

In this work is presented a new category of self-growing, fibrous, natural composite materials with controlled physical properties that can be produced in large quantities and over wide areas, based on mycelium, the main body of fungi. Mycelia from two types of edible, medicinal fungi, Ganoderma lucidum and Pleurotus ostreatus, have been carefully cultivated, being fed by two bio-substrates: cellulose and cellulose/potato-dextrose, the second being easier to digest by mycelium due to presence of simple sugars in its composition. After specific growing times the mycelia have been processed in order to cease their growth. Depending on their feeding substrate, the final fibrous structures showed different relative concentrations in polysaccharides, lipids, proteins and chitin. Such differences are reflected as alterations in morphology and mechanical properties. The materials grown on cellulose contained more chitin and showed higher Young’s modulus and lower elongation than those grown on dextrose-containing substrates, indicating that the mycelium materials get stiffer when their feeding substrate is harder to digest. All the developed fibrous materials were hydrophobic with water contact angles higher than 120°. The possibility of tailoring mycelium materials’ properties by properly choosing their nutrient substrates paves the way for their use in various scale applications.

Dynamic failure in two-phase materials

DOE PAGES

Fensin, S. J.; Walker, E. K.; Cerreta, E. K.; ...

2015-12-21

Previous experimental research has shown that microstructural features such as interfaces, inclusions, vacancies, and heterogeneities can all act as voidnucleation sites. However, it is not well understood how important these interfaces are to damage evolution and failure as a function of the surrounding parentmaterials. In this work, we present results on three different polycrystallinematerials: (1) Cu, (2) Cu-24 wt. %Ag, and (3) Cu-15 wt. %Nb which were studied to probe the influence of bi-metal interfaces onvoidnucleation and growth. These materials were chosen due to the range of difference in structure and bulk properties between the two phases. The initial resultsmore » suggest that when there are significant differences between the bulk properties (for example: stacking fault energy, melting temperature, etc.) the type of interface between the two parent materials does not principally control the damage nucleation and growth process. Rather, it is the “weaker” material that dictates the dynamic spall strength of the overall two-phase material.« less

Removal of heavy metals from emerging cellulosic low-cost adsorbents: a review

NASA Astrophysics Data System (ADS)

Malik, D. S.; Jain, C. K.; Yadav, Anuj K.

2017-09-01

Heavy metal pollution is a major problems in the environment. The impact of toxic metal ions can be minimized by different technologies, viz., chemical precipitation, membrane filtration, oxidation, reverse osmosis, flotation and adsorption. But among them, adsorption was found to be very efficient and common due to the low concentration of metal uptake and economically feasible properties. Cellulosic materials are of low cost and widely used, and very promising for the future. These are available in abundant quantity, are cheap and have low or little economic value. Different forms of cellulosic materials are used as adsorbents such as fibers, leaves, roots, shells, barks, husks, stems and seed as well as other parts also. Natural and modified types of cellulosic materials are used in different metal detoxifications in water and wastewater. In this review paper, the most common and recent materials are reviewed as cellulosic low-cost adsorbents. The elemental properties of cellulosic materials are also discussed along with their cellulose, hemicelluloses and lignin contents.

Hierarchically Porous Carbon Materials for CO 2 Capture: The Role of Pore Structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Estevez, Luis; Barpaga, Dushyant; Zheng, Jian

2018-01-17

With advances in porous carbon synthesis techniques, hierarchically porous carbon (HPC) materials are being utilized as relatively new porous carbon sorbents for CO2 capture applications. These HPC materials were used as a platform to prepare samples with differing textural properties and morphologies to elucidate structure-property relationships. It was found that high microporous content, rather than overall surface area was of primary importance for predicting good CO2 capture performance. Two HPC materials were analyzed, each with near identical high surface area (~2700 m2/g) and colossally high pore volume (~10 cm3/g), but with different microporous content and pore size distributions, which ledmore » to dramatically different CO2 capture performance. Overall, large pore volumes obtained from distinct mesopores were found to significantly impact adsorption performance. From these results, an optimized HPC material was synthesized that achieved a high CO2 capacity of ~3.7 mmol/g at 25°C and 1 bar.« less

On the uniqueness of measuring elastoplastic properties from indentation: The indistinguishable mystical materials

NASA Astrophysics Data System (ADS)

Chen, Xi; Ogasawara, Nagahisa; Zhao, Manhong; Chiba, Norimasa

2007-08-01

Indentation is widely used to extract material elastoplastic properties from the measured force-displacement curves. One of the most well-established indentation techniques utilizes dual (or plural) sharp indenters (which have different apex angles) to deduce key parameters such as the elastic modulus, yield stress, and work-hardening exponent for materials that obey the power-law constitutive relationship. However, the uniqueness of such analysis is not yet systematically studied or challenged. Here we show the existence of "mystical materials", which have distinct elastoplastic properties yet they yield almost identical indentation behaviors, even when the indenter angle is varied in a large range. These mystical materials are, therefore, indistinguishable by many existing indentation analyses unless extreme (and often impractical) indenter angles are used. Explicit procedures of deriving these mystical materials are established, and the general characteristics of the mystical materials are discussed. In many cases, for a given indenter angle range, a material would have infinite numbers of mystical siblings, and the existence maps of the mystical materials are also obtained. Furthermore, we propose two alternative techniques to effectively distinguish these mystical materials. The study in this paper addresses the important question of the uniqueness of indentation test, as well as providing useful guidelines to properly use the indentation technique to measure material elastoplastic properties.

Properties of concrete containing different type of waste materials as aggregate replacement exposed to elevated temperature – A review

NASA Astrophysics Data System (ADS)

Ghadzali, N. S.; Ibrahim, M. H. W.; Sani, M. S. H. Mohd; Jamaludin, N.; Desa, M. S. M.; Misri, Z.

2018-04-01

Concrete is the chief material of construction and it is non-combustible in nature. However, the exposure to the high temperature such as fire can lead to change in the concrete properties. Due to the higher temperature, several changes in terms of mechanical properties were observed in concrete such as compressive strength, modulus of elasticity, tensile strength and durability of concrete will decrease significantly at high temperature. The exceptional fire-proof achievement of concrete is might be due to the constituent materials of concrete such as its aggregates. The extensive use of aggregate in concrete will leads to depletion of natural resources. Hence, the use of waste and other recycled and by-product material as aggregates replacements becomes a leading research. This review has been made on the utilization of waste materials in concrete and critically evaluates its effects on the concrete performances during the fire exposure. Therefore, the objective of this paper is to review the previous search work regarding the concrete containing waste material as aggregates replacement when exposed to elevated temperature and come up with different design recommendations to improve the fire resistance of structures.

Methods and apparatus for moving and separating materials exhibiting different physical properties

DOEpatents

Peterson, Stephen C.; Brimhall, Owen D.; McLaughlin, Thomas J.; Baker, Charles D.; Sparks, Sam L.

1991-01-01

Methods and apparatus for controlling the movement of materials having different physical properties when one of the materials is a fluid. The invention does not rely on flocculation, sedimentation, centrifugation, the buoyancy of the materials, or any other gravity dependent characteristic, in order to achieve its desired results. The methods of the present invention provide that a first acoustic wave is propagated through a vessel containing the materials. A second acoustic wave, at a frequency different than the first acoustic wave, is also propagated through the vessel so that the two acoustic waves are superimposed upon each other. The superimposition of the two waves creates a beat frequency wave. The beat frequency wave comprises pressure gradients dividing regions of maximum and minimum pressure. The pressure gradients and the regions of maximum and minimum pressure move through space and time at a group velocity. The moving pressure gradients and regions of maximum and minimum pressure act upon the materials so as to move one of the materials towards a predetermined location in the vessel. The present invention provides that the materials may be controllably moved toward a location, aggregated at a particular location, or physically separated from each other.

Elastic and microplastic properties of titanium in different structural states

NASA Astrophysics Data System (ADS)

Kardashev, B. K.; Betekhtin, V. I.; Kadomtsev, A. G.; Narykova, M. V.; Kolobov, Yu. R.

2017-09-01

The behavior of elastic (Young's modulus) and microplastic properties of titanium depending on the initial structure and subsequent severe plastic deformation that transforms the material (concerning the grain size) into the submicrocrystalline structural state has been studied. It has been shown that, to a great extent, different initial structures of the metal predetermine its elastic properties after deformation.

Application of materials database (MAT.DB.) to materials education

NASA Technical Reports Server (NTRS)

Liu, Ping; Waskom, Tommy L.

1994-01-01

Finding the right material for the job is an important aspect of engineering. Sometimes the choice is as fundamental as selecting between steel and aluminum. Other times, the choice may be between different compositions in an alloy. Discovering and compiling materials data is a demanding task, but it leads to accurate models for analysis and successful materials application. Mat. DB. is a database management system designed for maintaining information on the properties and processing of engineered materials, including metals, plastics, composites, and ceramics. It was developed by the Center for Materials Data of American Society for Metals (ASM) International. The ASM Center for Materials Data collects and reviews material property data for publication in books, reports, and electronic database. Mat. DB was developed to aid the data management and material applications.

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.

Reformulating Polycaprolactone Fumarate to Eliminate Toxic Diethylene Glycol: Effects of Polymeric Branching and Autoclave Sterilization on Material Properties

PubMed Central

Runge, M. Brett; Wang, Huan; Spinner, Robert J; Windebank, Anthony J; Yaszemski, Michael J.

2011-01-01

Polycaprolactone fumarate (PCLF) is a cross-linkable derivate of polycaprolactone diol that has been shown to be an effective nerve conduit material that supports regeneration across segmental nerve defects and has warranted future clinical trials. Degradation of the previously studied PCLF (PCLFDEG) releases toxic small molecules of diethylene glycol used as the initiator for the synthesis of polycaprolactone diol. In an effort to eliminate this toxic degradation product we present a strategy for the synthesis of PCLF from either propylene glycol (PCLFPPD) or glycerol (PCLFGLY). PCLFPPD is linear and resembles the previously studied PCLFDEG, while PCLFGLY is branched and exhibits dramatically different material properties. The synthesis and characterization of their thermal, rheological, and mechanical properties are reported. The results show that the linear PCLFPPD has material properties similar to the previously studied PCLFDEG. The branched PCLFGLY exhibits dramatically lower crystalline properties resulting in lower rheological and mechanical moduli, and is therefore a more compliant material. In addition, the question of an appropriate FDA approvable sterilization method is addressed. This study shows that autoclave sterilization on PCLF materials is an acceptable sterilization method for cross-linked PCLF and has minimal effect on the PCLF thermal and mechanical properties. PMID:21911087

Characterization and modeling of an advanced flexible thermal protection material for space applications

NASA Technical Reports Server (NTRS)

Clayton, Joseph P.; Tinker, Michael L.

1991-01-01

This paper describes experimental and analytical characterization of a new flexible thermal protection material known as Tailorable Advanced Blanket Insulation (TABI). This material utilizes a three-dimensional ceramic fabric core structure and an insulation filler. TABI is the leading candidate for use in deployable aeroassisted vehicle designs. Such designs require extensive structural modeling, and the most significant in-plane material properties necessary for model development are measured and analytically verified in this study. Unique test methods are developed for damping measurements. Mathematical models are developed for verification of the experimental modulus and damping data, and finally, transverse properties are described in terms of the inplane properties through use of a 12-dof finite difference model of a simple TABI configuration.

Actuators Based on Liquid Crystalline Elastomer Materials

PubMed Central

Jiang, Hongrui; Li, Chensha; Huang, Xuezhen

2013-01-01

Liquid crystalline elastomers (LCEs) exhibit a number of remarkable physical effects, including the unique, high-stroke reversible mechanical actuation when triggered by external stimuli. This article reviews some recent exciting developments in the field of LCEs materials with an emphasis on their utilization in actuator applications. Such applications include artificial muscles, industrial manufacturing, health and microelectromechanical systems (MEMS). With suitable synthetic and preparation pathways and well-controlled actuation stimuli, such as heat, light, electric and magnetic field, excellent physical properties of LCE materials can be realized. By comparing the actuating properties of different systems, general relationships between the structure and the property of LCEs are discussed. How these materials can be turned into usable devices using interdisciplinary techniques is also described. PMID:23648966

Elevated Temperature Testing and Modeling of Advanced Toughened Ceramic Materials

NASA Technical Reports Server (NTRS)

Keith, Theo G.

2005-01-01

The purpose of this report is to provide a final report for the period of 12/1/03 through 11/30/04 for NASA Cooperative Agreement NCC3-776, entitled "Elevated Temperature Testing and Modeling of Advanced Toughened Ceramic Materials." During this final period, major efforts were focused on both the determination of mechanical properties of advanced ceramic materials and the development of mechanical test methodologies under several different programs of the NASA-Glenn. The important research activities made during this period are: 1. Mechanical properties evaluation of two gas-turbine grade silicon nitrides. 2) Mechanical testing for fuel-cell seal materials. 3) Mechanical properties evaluation of thermal barrier coatings and CFCCs and 4) Foreign object damage (FOD) testing.

Actuators based on liquid crystalline elastomer materials

NASA Astrophysics Data System (ADS)

Jiang, Hongrui; Li, Chensha; Huang, Xuezhen

2013-05-01

Liquid crystalline elastomers (LCEs) exhibit a number of remarkable physical effects, including the unique, high-stroke reversible mechanical actuation when triggered by external stimuli. This article reviews some recent exciting developments in the field of LCE materials with an emphasis on their utilization in actuator applications. Such applications include artificial muscles, industrial manufacturing, health and microelectromechanical systems (MEMS). With suitable synthetic and preparation pathways and well-controlled actuation stimuli, such as heat, light, electric and magnetic fields, excellent physical properties of LCE materials can be realized. By comparing the actuating properties of different systems, general relationships between the structure and the properties of LCEs are discussed. How these materials can be turned into usable devices using interdisciplinary techniques is also described.

“Smart” Materials Based on Cellulose: A Review of the Preparations, Properties, and Applications

PubMed Central

Qiu, Xiaoyun; Hu, Shuwen

2013-01-01

Cellulose is the most abundant biomass material in nature, and possesses some promising properties, such as mechanical robustness, hydrophilicity, biocompatibility, and biodegradability. Thus, cellulose has been widely applied in many fields. “Smart” materials based on cellulose have great advantages—especially their intelligent behaviors in reaction to environmental stimuli—and they can be applied to many circumstances, especially as biomaterials. This review aims to present the developments of “smart” materials based on cellulose in the last decade, including the preparations, properties, and applications of these materials. The preparations of “smart” materials based on cellulose by chemical modifications and physical incorporating/blending were reviewed. The responsiveness to pH, temperature, light, electricity, magnetic fields, and mechanical forces, etc. of these “smart” materials in their different forms such as copolymers, nanoparticles, gels, and membranes were also reviewed, and the applications as drug delivery systems, hydrogels, electronic active papers, sensors, shape memory materials and smart membranes, etc. were also described in this review. PMID:28809338

Superhydrophobic Silicon Nanocrystal-Silica Aerogel Hybrid Materials: Synthesis, Properties, and Sensing Application.

PubMed

Kehrle, Julian; Purkait, Tapas K; Kaiser, Simon; Raftopoulos, Konstantinos N; Winnacker, Malte; Ludwig, Theresa; Aghajamali, Maryam; Hanzlik, Marianne; Rodewald, Katia; Helbich, Tobias; Papadakis, Christine M; Veinot, Jonathan G C; Rieger, Bernhard

2018-04-24

Silicon nanocrystals (SiNCs) are abundant and exhibit exquisitely tailorable optoelectronic properties. The incorporation of SiNCs into highly porous and lightweight substrates such as aerogels leads to hybrid materials possessing the attractive features of both materials. This study describes the covalent deposition of SiNCs on and intercalation into silica aerogels, explores the properties, and demonstrates a prototype sensing application of the composite material. SiNCs of different sizes were functionalized with triethoxyvinylsilane (TEVS) via a radical grafting approach and subsequently used for the synthesis of photoluminescent silica hybrids. The resulting SiNC-containing aerogels possess high porosities, SiNC-based size-dependent photoluminescence, transparency, and a superhydrophobic macroscopic surface. The materials were used to examine the photoluminescence response toward low concentrations of 3-nitrotoluene (270 μM), demonstrating their potential as a sensing platform for high-energy materials.

In vitro toxicity analysis of nanoscale aluminum: Particle size and shape effects

NASA Astrophysics Data System (ADS)

Palazuelos Jorganes, Maria

2007-12-01

Nanostructured materials promise to revolutionize many key areas of science and technology. As our ability to manipulate matter at the nanoscale increases, there is a need to assess the effects of these materials on human health and the environment. Materials at the nanoscale are interesting and useful because they possess properties that are different from the equivalent bulk or molecular scale. These same properties can make toxicological profiles very different from those of the same materials on a different scale. There is a rising consensus that toxicity analysis of nanomaterials should start from a thorough physicochemical characterization of the materials under investigation in order to be able to establish a proper correlation between the nanoparticles characteristics and their effects and behavior in physiological environments. This research is a clear example of the necessity of comprehensive studies when investigating the toxicity of nanomaterials. Aluminum nanoparticles are being extensively used for their very unique energetic properties. These materials offer a very promising market that is fostering many startup companies which are expected to consolidate on strong technological positions. Aluminum is generally recognized as a non-toxic material to humans and it is widely used for applications which imply direct human contact. The effect of aluminum nanoparticles in human health is still an unknown. My research consisted of an in vitro toxicity screening of aluminum materials from nano to micron size, including spherical irregularly shaped particles. Several issues relating to size, shape, detection and characterization of nanoparticles in the different environments relevant to in vitro toxicity analysis were addressed and suitable protocols were developed. Lung human epithelial cells were exposed to different concentrations of these materials and the effects were analyzed by means of various toxicity tests. Some of the materials investigated caused elevated in vitro toxicity. Cells endocytosed the particles and a clear correlation between the particle size, shape and the effects observed was established. The hypothesized toxicity mechanism was explored using different analytical techniques. The detected toxicity of aluminum nanoparticles was demonstrated to be a direct effect of their reactivity inside the cells.

Physical Properties of Granulates Used in Analogue Experiments of Caprock Failure and Sediment Remobilisation

NASA Astrophysics Data System (ADS)

Kukowski, N.; Warsitzka, M.; May, F.

2014-12-01

Geological systems consisting of a porous reservoir and a low-permeable caprock are prone to hydraulic fracturing, if pore pressure rises to the effective stress. Under certain conditions, hydraulic fracturing is associated with sediment remobilisation, e.g. sand injections or pipes, leading to reduced seal capacity of the caprock. In dynamically scaled analogue experiments using granular materials and air pressure, we intent to investigate strain patterns and deformation mechanisms during caprock failure and fluidisation of shallow over-pressured reservoirs. The aim of this study is to improve the understanding of leakage potential of a sealing formation and the fluidisation potential of a reservoir formation depending on rock properties and effective stress. For reliable interpretation of analogue experiments, physical properties of analogue materials, e.g. frictional strength, cohesion, density, permeability etc., have to be correctly scaled according to those of their natural equivalents. The simulation of caprock requires that the analogue material possess a low permeability and is capable to shear failure and tensional failure. In contrast, materials representing the reservoir have to possess high porosity and low shear strength. In order to find suitable analogue materials, we measured the stress-strain behaviour and the permeability of over 25 different types of natural and artificial granular materials, e.g. glass powder, siliceous microspheres, diatomite powder, loess, or plastic granulate. Here, we present data of frictional parameters, compressibility and permeability of these granular materials characterized as a function of sphericity, grain size, and density. The repertoire of different types of granulates facilitates the adjustment of accurate mechanical properties in the analogue experiments. Furthermore, conditions during seal failure and fluidisation can be examined depending on the wide range of varying physical properties.

Optical properties of dissolved organic matter (DOM): Effects of biological and photolytic degradation

USGS Publications Warehouse

Hansen, Angela; Kraus, Tamara; Pellerin, Brian; Fleck, Jacob; Downing, Bryan D.; Bergamaschi, Brian

2016-01-01

Advances in spectroscopic techniques have led to an increase in the use of optical properties (absorbance and fluorescence) to assess dissolved organic matter (DOM) composition and infer sources and processing. However, little information is available to assess the impact of biological and photolytic processing on the optical properties of original DOM source materials. We measured changes in commonly used optical properties and indices in DOM leached from peat soil, plants, and algae following biological and photochemical degradation to determine whether they provide unique signatures that can be linked to original DOM source. Changes in individual optical parameters varied by source material and process, with biodegradation and photodegradation often causing values to shift in opposite directions. Although values for different source materials overlapped at the end of the 111-day lab experiment, multivariate statistical analyses showed that unique optical signatures could be linked to original DOM source material even after degradation, with 17 optical properties determined by discriminant analysis to be significant (p<0.05) in distinguishing between DOM source and environmental processing. These results demonstrate that inferring the source material from optical properties is possible when parameters are evaluated in combination even after extensive biological and photochemical alteration.

Bioink properties before, during and after 3D bioprinting.

PubMed

Hölzl, Katja; Lin, Shengmao; Tytgat, Liesbeth; Van Vlierberghe, Sandra; Gu, Linxia; Ovsianikov, Aleksandr

2016-09-23

Bioprinting is a process based on additive manufacturing from materials containing living cells. These materials, often referred to as bioink, are based on cytocompatible hydrogel precursor formulations, which gel in a manner compatible with different bioprinting approaches. The bioink properties before, during and after gelation are essential for its printability, comprising such features as achievable structural resolution, shape fidelity and cell survival. However, it is the final properties of the matured bioprinted tissue construct that are crucial for the end application. During tissue formation these properties are influenced by the amount of cells present in the construct, their proliferation, migration and interaction with the material. A calibrated computational framework is able to predict the tissue development and maturation and to optimize the bioprinting input parameters such as the starting material, the initial cell loading and the construct geometry. In this contribution relevant bioink properties are reviewed and discussed on the example of most popular bioprinting approaches. The effect of cells on hydrogel processing and vice versa is highlighted. Furthermore, numerical approaches were reviewed and implemented for depicting the cellular mechanics within the hydrogel as well as for prediction of mechanical properties to achieve the desired hydrogel construct considering cell density, distribution and material-cell interaction.

Engineering thermoplastics for additive manufacturing: a critical perspective with experimental evidence to support functional applications.

PubMed

Cicala, Gianluca; Latteri, Alberta; Del Curto, Barbara; Lo Russo, Alessio; Recca, Giuseppe; Farè, Silvia

2017-01-28

Among additive manufacturing techniques, the filament-based technique involves what is referred to as fused deposition modeling (FDM). FDM materials are currently limited to a selected number of polymers. The present study focused on investigating the potential of using high-end engineering polymers in FDM. In addition, a critical review of the materials available on the market compared with those studied here was completed. Different engineering thermoplastics, ranging from industrial grade polycarbonates to novel polyetheretherketones (PEEKs), were processed by FDM. Prior to this, for innovative filaments based on PEEK, extrusion processing was carried out. Mechanical properties (i.e., tensile and flexural) were investigated for each extruded material. An industrial-type FDM machine (Stratasys Fortus® 400 mc) was used to fully characterize the effect of printing parameters on the mechanical properties of polycarbonate. The obtained properties were compared with samples obtained by injection molding. Finally, FDM samples made of PEEK were also characterized and compared with those obtained by injection molding. The effect of raster to raster air gap and raster angle on tensile and flexural properties of printed PC was evidenced; the potential of PEEK filaments, as novel FDM material, was highlighted in comparison to state of the art materials. Comparison with injection molded parts allowed to better understand FDM potential for functional applications. The study discussed pros and cons of the different materials. Finally, the development of novel PEEK filaments achieved important results offering a novel solution to the market when high mechanical and thermal properties are required.

Zirconia-hydroxyapatite composite material with micro porous structure.

PubMed

Matsumoto, Takuya Junior; An, Sang-Hyun; Ishimoto, Takuya; Nakano, Takayoshi; Matsumoto, Takuya; Imazato, Satoshi

2011-11-01

Titanium plates and apatite blocks are commonly used for restoring large osseous defects in dental and orthopedic surgery. However, several cases of allergies against titanium have been recently reported. Also, sintered apatite block does not possess sufficient mechanical strength. In this study, we attempted to fabricate a composite material that has mechanical properties similar to biocortical bone and high bioaffinity by compounding hydroxyapatite (HAp) with the base material zirconia (ZrO(2)), which possesses high mechanical properties and low toxicity toward living organisms. After mixing the raw material powders at several different ZrO(2)/HAp mixing ratios, the material was compressed in a metal mold (8 mm in diameter) at 5 MPa. Subsequently, it was sintered for 5 h at 1500°C to obtain the ZrO(2)/HAp composite. The mechanical property and biocompatibility of materials were investigated. Furthermore, osteoconductivity of materials was investigated by animal studies. A composite material with a minute porous structure was successfully created using ZrO(2)/HAp powders, having different particle sizes, as the starting material. The material also showed high protein adsorption and a favorable cellular affinity. When the mixing ratio was ZrO(2)/HAp=70/30, the strength was equal to cortical bone. Furthermore, in vivo experiments confirmed its high osteoconductivity. The composite material had strength similar to biocortical bones with high cell and tissue affinities by compounding ZrO(2) and HAp. The ZrO(2)/HAp composite material having micro porous structure would be a promising bone restorative material. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Materials for x-ray refractive lenses minimizing wavefront distortions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roth, Thomas; Alianelli, Lucia; Lengeler, Daniel

2017-06-09

Refraction through curved surfaces, reflection from curved mirrors in grazing incidence, and diffraction from Fresnel zone plates are key hard x-ray focusing mechanisms. In this article, we present materials used for refractive x-ray lenses. Important properties of such x-ray lenses include focusing strength, shape, and the material’s homogeneity and absorption coefficient. Both the properties of the initial material and the fabrication process result in a lens with imperfections, which can lead to unwanted wavefront distortions. Different fabrication methods for one-dimensional and two-dimensional focusing lenses are presented, together with the respective benefits and inconveniences that are mostly due to shape fidelity.more » Different materials and material grades have been investigated in terms of their homogeneity and the absence of inclusions. Single-crystalline materials show high homogeneity, but suffer from unwanted diffracted radiation, which can be avoided using amorphous materials. Lastly, we show that shape imperfections can be corrected using a correction lens.« less

Effect of packing material on methane activation in a dielectric barrier discharge reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jo, Sungkwon; Hoon Lee, Dae; Seok Kang, Woo

2013-12-15

The conversion of methane is measured in a planar-type dielectric barrier discharge reactor using γ-Al{sub 2}O{sub 3} (sphere), α-Al{sub 2}O{sub 3} (sphere), and γ-Al{sub 2}O{sub 3} (16–20 mesh). Investigations on the surface properties and shape of the three packing materials clearly indicate that methane activation is considerably affected by the material used. Capacitances inside the discharge gap are estimated from charge–voltage plots, and a comparison of the generated and transferred charges for different packing conditions show that the difference in surface properties between γ- and α-phase Al{sub 2}O{sub 3} affects the discharge characteristics. Moreover, all packing conditions show different chargemore » characteristics that are related to the electron density. Finally, the packing material's shape affects the local electron temperature, which is strongly related to methane conversion. The combined results indicate that both microscale and macroscale variations in a packing material affect the discharge characteristics, and a packing material should be considered carefully for effective methane activation.« less

Preparation and properties of hybrid materials for high-rise constructions

NASA Astrophysics Data System (ADS)

Matseevich, Tatyana

2018-03-01

The theme of the research is important because it allows to use hybrid materials as finishing in the high-rise constructions. The aim of the study was the development of producing coloured hybrid materials based on liquid glass, a polyisocyanate, epoxy resin and 2.4-toluylenediisocyanate. The detailed study of the process of stress relaxation at different temperatures in the range of 20-100°C was provided. The study found that the obtained materials are subject to the simplified technology. The materials easy to turn different colors, and dyes (e.g. Sudan blue G) are the catalysts for the curing process of the polymeric precursors. The materials have improved mechanical relaxation properties, possess different color and presentable, can be easily combined with inorganic base (concrete, metal). The limit of compressive strength varies from 32 to 17.5 MPa at a temperature of 20 to 100°C. The values σ∞ are from 20.4 to 7.7 MPa within the temperature range from 20 to 100°C. The physical parameters of materials were evaluated basing on the data of stress relaxation: the initial stress σ0, which occurs at the end of the deformation to a predetermined value; quasi-equilibrium stress σ∞, which persists for a long time relaxation process. Obtained master curves provide prediction relaxation behavior for large durations of relaxation. The study obtained new results. So, the addition of epoxy resin in the composition of the precursor improves the properties of hybrid materials. By the method of IR spectroscopy identified chemical transformations in the course of obtaining the hybrid material. Evaluated mechanical performance of these materials is long-time. Applied modern physically-based memory functions, which perfectly describe the stress relaxation process.

Design of electro-active polymer gels as actuator materials

NASA Astrophysics Data System (ADS)

Popovic, Suzana

Smart materials, alternatively called active or adaptive, differ from passive materials in their sensing and activation capability. These materials can sense changes in environment such as: electric field, magnetic field, UV light, pH, temperature. They are capable of responding in numerous ways. Some change their stiffness properties (electro-rheological fluids), other deform (piezos, shape memory alloys, electrostrictive materials) or change optic properties (electrochromic polymers). Polymer gels are one of such materials which can change the shape, volume and even optical properties upon different applied stimuli. Due to their low stiffness property they are capable of having up to 100% of strain in a short time, order of seconds. Their motion resembles the one of biosystems, and they are often seen as possible artificial muscle materials. Despite their delicate nature, appropriate design can make them being used as actuator materials which can form controllable surfaces and mechanical switches. In this study several different groups of polymer gel material were investigated: (a) acrylamide based gels are sensitive to pH and electric field and respond in volume change, (b) polyacrylonitrile (PAN) gel is sensitive to pH and electric field and responds in axial strain and bending, (c) polyvinylalcohol (PVA) gel is sensitive to electric field and responds in axial strain and bending and (d) perfluorinated sulfonic acid membrane, Nafion RTM, is sensitive to electric field and responds in bending. Electro-mechanical and chemo-mechanical behavior of these materials is a function of a variety of phenomena: polymer structure, affinity of polymer to the solvent, charge distribution within material, type of solvent, elasticity of polymer matrix, etc. Modeling of this behavior is a task aimed to identify what is driving mechanism for activation and express it in a quantitative way in terms of deformation of material. In this work behavior of the most promising material as an actuator material, Nafion 117, was simulated. It was suggested that dominant phenomenon causing the material deformation is non-uniform water distribution within a material, that causes it to expand on one side and shrink on the other, macroscopically inducing bending of membrane. Uneven distribution of water is believed to be under the influence of two processes, electroosmosis and self-diffusion of free water.

Meso-Scale Experimental & Numerical Studies for Predicting Macro-scale Performance of Advanced Reactive Materials (ARMs)

DTIC Science & Technology

2015-04-01

of impact-initiated reactions in Ti-Al-B based reactive materials in the form of compacts of powders of different sizes and morphologies . The major...More specifically, the influence of material-inherent elastic/plastic properties and reactant configuration (e.g., porosity, morphology , spacing...materials in the form of compacts of powders of different sizes and morphologies . The major goal is to delineate how processes of localized deformation and

Experimental and numerical characterization of expanded glass granules

NASA Astrophysics Data System (ADS)

Chaudry, Mohsin Ali; Woitzik, Christian; Düster, Alexander; Wriggers, Peter

2018-07-01

In this paper, the material response of expanded glass granules at different scales and under different boundary conditions is investigated. At grain scale, single particle tests can be used to determine properties like Young's modulus or crushing strength. With experiments like triaxial and oedometer tests, it is possible to examine the bulk mechanical behaviour of the granular material. Our experimental investigation is complemented by a numerical simulation where the discrete element method is used to compute the mechanical behaviour of such materials. In order to improve the simulation quality, effects such as rolling resistance, inelastic behaviour, damage, and crushing are also included in the discrete element method. Furthermore, the variation of the material properties of granules is modelled by a statistical distribution and included in our numerical simulation.

Study on tribological and electrochemistry properties of metal materials in H2O2 solutions

NASA Astrophysics Data System (ADS)

Yuan, Chengqing; Yu, Li; Li, Jian; Yan, Xinping

2012-03-01

Hydrogen peroxide (H2O2) is a kind of ideal green propellant. It is crucial to study the wear behavior and failure modes of the metal materials under the strong oxidizing environment of H2O2. This study aims to investigate the wear of rubbing pairs of 2Cr13 stainless steel against 1045 metal in H2O2 solutions, which has a great effect on wear, the decomposition and damage mechanism of materials. The comparison analysis of the friction coefficients, wear mass loss, worn surface topographies and current densities was conducted under different concentrations of H2O2 solutions. There were significant differences in the tribological and electrochemistry properties of the rubbing pairs in different H2O2 solutions.

Behaviour study of thick laminated composites: Experimentation and finite element analyses

NASA Astrophysics Data System (ADS)

Duchaine, Francois

In today's industries, it is common practice to utilize composite materials in very large and thick structures like bridge decks, high pressure vessels, wind turbine blades and aircraft parts to mention a few. Composite materials are highly favoured due to their physical characteristics: low weight, low cost, adaptable mechanical properties, high specific strength and stiffness. The use of composite materials for large structures has however raised several concerns in the prediction of the behaviour of thick laminated composite parts. A lack of knowledge and experience in the use of composite materials during the design, sizing and manufacturing of thick composite parts can lead to catastrophic events. In this thesis, it was supposed that the elastic material properties may vary with the laminate thickness. In order to measure the influence of the thickness on nine orthotropic elastic material properties (E1, E2, E3, nu12, nu 13, nu23, G12, G13 and G23), three categories of thickness have been defined using a comparison between the classical lamination theory (CLT), different beam theories and a numerical 3D solid finite element analysis (FEA) model. The defined categories are: thin laminates for thicknesses below 6 mm (0.236"), moderately thick laminates for thicknesses up to 16 mm (0.630") and thick laminates for thicknesses above 16 mm (0.630"). For three different thicknesses (thin -- 1.5 mm, moderately thick -- 10 mm and thick -- 20 mm), the influence of the thickness on the orthotropic elastic material properties of unidirectional (UD) fibreglass/epoxy laminates has been measured. A torsion test on rectangular bar is also proposed to measure the influence of the thickness on G13 and G23. The nine elastic material properties, in function of the thickness, have been used in CLT and 3D solid FEA model in order to predict the axial Young's modulus and Poisson's ratios of cross-ply and quasi-isotropic laminates. Experimental results have also been obtained for those laminates. The analysis of test results with CLT and FEA showed that the variation of elastic material properties with the thickness is not significant for in-plane problems. On the other hand, a substantial influence has been highlighted on UD elastic material properties driven by the matrix like E 2, E3, nu13 and G12. .

Strain Rate and Anisotropic Microstructure Dependent Mechanical Behaviors of Silkworm Cocoon Shells

PubMed Central

Xu, Jun; Zhang, Wen; Gao, Xiang; Meng, Wanlin; Guan, Juan

2016-01-01

Silkworm cocoons are multi-layered composite structures comprised of high strength silk fiber and sericin, and their mechanical properties have been naturally selected to protect pupas during metamorphosis from various types of external attacks. The present study attempts to gain a comprehensive understanding of the mechanical properties of cocoon shell materials from wild silkworm species Antheraea pernyi under dynamic loading rates. Five dynamic strain rates from 0.00625 s-1 to 12.5 s-1 are tested to show the strain rate sensitivity of the cocoon shell material. In the meantime, the anisotropy of the cocoon shell is considered and the cocoon shell specimens are cut along 0°, 45° and 90° orientation to the short axis of cocoons. Typical mechanical properties including Young’s modulus, yield strength, ultimate strength and ultimate strain are extracted and analyzed from the stress-strain curves. Furthermore, the fracture morphologies of the cocoon shell specimens are observed under scanning electron microscopy to help understand the relationship between the mechanical properties and the microstructures of the cocoon material. A discussion on the dynamic strain rate effect on the mechanical properties of cocoon shell material is followed by fitting our experimental results to two previous models, and the effect could be well explained. We also compare natural and dried cocoon materials for the dynamic strain rate effect and interestingly the dried cocoon shells show better overall mechanical properties. This study provides a different perspective on the mechanical properties of cocoon material as a composite material, and provides some insight for bio-inspired engineering materials. PMID:26939063

Ab initio study of (Fe, Ni) doped GaAs: Magnetic, electronic properties and Faraday rotation

NASA Astrophysics Data System (ADS)

Sbai, Y.; Ait Raiss, A.; Bahmad, L.; Benyoussef, A.

2017-06-01

The interesting diluted magnetic semiconductor (DMS), Gallium Arsenide (GaAs), was doped with the transition metals magnetic impurities: iron (Fe) and Nickel (Ni), in one hand to study the magnetic and magneto-optical properties of the material Ga(Fe, Ni) As, in the other hand to investigate the effect of the doping on the properties of this material, the calculations were performed within the spin polarized density functional theory (DFT) and generalized gradient approximation (GGA) with AKAI KKR-CPA method, the density of states (DOS) for different doping concentrations were calculated, giving the electronical properties, as well as the magnetic state and magnetic states energy, also the effect of these magnetic impurities on the Faraday rotation as magneto-optical property. Furthermore, we found the stable magnetic state for our doped material GaAs.

Harmful Cyanobacterial Material Production in the North Han River (South Korea): Genetic Potential and Temperature-Dependent Properties.

PubMed

Kim, Keonhee; Park, Chaehong; Yoon, Youngdae; Hwang, Soon-Jin

2018-03-03

Cyanobacteria synthesize various harmful materials, including off-flavor substances and toxins, that are regarded as potential socio-economic and environmental hazards in freshwater systems, however, their production is still not well understood. In this study, we investigated the potential and properties of harmful materials produced by cyanobacteria, depending on temperature, and undertook a phylogenetic analysis of cyanobacteria present in the North Han River (South Korea). Production potentials were evaluated using gene-specific probes, and the harmful material production properties of strains showing positive potentials were further characterized at different temperatures in the range 15 to 30 °C. We identified six cyanobacterial strains based on 16S rDNA analysis: two morphological types (coiled and straight type) of Dolichospermum circinale, Aphanizomenon flos-aquae, Oscillatoria limosa, Planktothricoides raciborskii, Pseudanabaena mucicola , and Microcystis aeruginosa . We confirmed that cyanobacterial strains showing harmful material production potential produced the corresponding harmful material, and their production properties varied with temperature. Total harmful material production was maximal at 20~25 °C, a temperature range optimal for cell growth. However, harmful material productivity was highest at 15 °C. These results indicate that the expression of genes related to synthesis of harmful materials can vary depending on environmental conditions, resulting in variable harmful material production, even within the same cyanobacterial strains.

Bulk microstructure and local elastic properties of carbon nanocomposites studied by impulse acoustic microscopy technique

NASA Astrophysics Data System (ADS)

Levin, V.; Petronyuk, Yu.; Morokov, E.; Chernozatonskii, L.; Kuzhir, P.; Fierro, V.; Celzard, A.; Bellucci, S.; Bistarelli, S.; Mastrucci, M.; Tabacchioni, I.

2016-05-01

Bulk microstructure and elastic properties of epoxy-nanocarbon nanocomposites for diverse types and different content of carbon nanofiller has been studied by using impulse acoustic microscopy technique. It has been shown occurrence of various types of mesoscopic structure formed by nanoparticles inside the bulk of nanocomposite materials, including nanoparticle conglomerates and nanoparticle aerogel systems. In spite of the bulk microstructure, nanocarbon composites demonstrate elastic uniformity and negligible influence of nanofiller on elastic properties of carbon nanocomposite materials.

Microfibrillated cellulose - its barrier properties and applications in cellulosic materials: a review.

PubMed

Lavoine, Nathalie; Desloges, Isabelle; Dufresne, Alain; Bras, Julien

2012-10-01

Interest in microfibrillated cellulose (MFC) has been increasing exponentially. During the last decade, this bio-based nanomaterial was essentially used in nanocomposites for its reinforcement property. Its nano-scale dimensions and its ability to form a strong entangled nanoporous network, however, have encouraged the emergence of new high-value applications. In previous years, its mode of production has completely changed, as many forms of optimization have been developed. New sources, new mechanical processes, and new pre- and post-treatments are currently under development to reduce the high energy consumption and produce new types of MFC materials on an industrial scale. The nanoscale characterization possibilities of different MFC materials are thus increasing intensively. Therefore, it is critical to review such MFC materials and their properties. Moreover, very recent studies have proved the significant barrier properties of MFC. Hence, it is proposed to focus on the barrier properties of MFC used in films, in nanocomposites, or in paper coating. Copyright © 2012 Elsevier Ltd. All rights reserved.

Microgravity

NASA Image and Video Library

1997-11-01

The purpose of the experiments for the Advanced Automated Directional Solidification Furnace (AADSF) is to determine how gravity-driven convection affects the composition and properties of alloys (mixtures of two or more materials, usually metal). During the USMP-4 mission, the AADSF will solidify crystals of lead tin telluride and mercury cadmium telluride, alloys of compound semiconductor materials used to make infrared detectors and lasers, as experiment samples. Although these materials are used for the same type application their properties and compositional uniformity are affected differently during the solidification process.

Viking Landers and remote sensing

NASA Technical Reports Server (NTRS)

Moore, H. J.; Jakosky, B. M.; Christensen, P. R.

1987-01-01

Thermal and radar remote sensing signatures of the materials in the lander sample fields can be crudely estimated from evaluations of their physical-mechanical properties, laboratory data on thermal conductivities and dielectric constants, and theory. The estimated thermal inertias and dielectric constants of some of the materials in the sample field are close to modal values estimated from orbital and earth-based observations. This suggests that the mechanical properties of the surface materials of much of Mars will not be significantly different that those of the landing sites.

Biodegradable ceramic-polymer composites for biomedical applications: A review.

PubMed

Dziadek, Michal; Stodolak-Zych, Ewa; Cholewa-Kowalska, Katarzyna

2017-02-01

The present work focuses on the state-of-the-art of biodegradable ceramic-polymer composites with particular emphasis on influence of various types of ceramic fillers on properties of the composites. First, the general needs to create composite materials for medical applications are briefly introduced. Second, various types of polymeric materials used as matrices of ceramic-containing composites and their properties are reviewed. Third, silica nanocomposites and their material as well as biological characteristics are presented. Fourth, different types of glass fillers including silicate, borate and phosphate glasses and their effect on a number of properties of the composites are described. Fifth, wollastonite as a composite modifier and its effect on composite characteristics are discussed. Sixth, composites containing calcium phosphate ceramics, namely hydroxyapatite, tricalcium phosphate and biphasic calcium phosphate are presented. Finally, general possibilities for control of properties of composite materials are highlighted. Copyright © 2016 Elsevier B.V. All rights reserved.

Anisotropic characterization of magnetorheological materials

NASA Astrophysics Data System (ADS)

Dohmen, E.; Modler, N.; Gude, M.

2017-06-01

For the development of energy efficient lightweight parts novel function integrating materials are needed. Concerning this field of application magnetorheological (MR) fluids, MR elastomers and MR composites are promising materials allowing the adjustment of mechanical properties by an external magnetic field. A key issue for operating such structures in praxis is the magneto-mechanical description. Most rheological properties are gathered at laboratory conditions for high magnetic flux densities and a single field direction, which does not correspond to real praxis conditions. Although anisotropic formation of superstructures can be observed in MR suspensions (Fig. 1) or experimenters intentionally polymerize MR elastomers with anisotropic superstructures these MR materials are usually described in an external magnetic field as uniform, isotropic materials. This is due to missing possibilities for experimentally measuring field angle dependent properties and ways of distinguishing between material properties and frictional effects. Just a few scientific works experimentally investigated the influence of different field angles (Ambacher et al., 1992; Grants et al., 1990; Kuzhir et al., 2003) [1-3] or the influence of surface roughness on the shear behaviour of magnetic fluids (Tang and Conrad, 1996) [4]. The aim of this work is the introduction of a novel field angle cell allowing the determination of anisotropic mechanical properties for various MR materials depending on the applied magnetic field angle.

HBM Mice Have Altered Bone Matrix Composition And Improved Material Toughness

DOE PAGES

Ross, Ryan D.; Mashiatulla, Maleeha; Acerbo, Alvin S.; ...

2016-05-26

Here, the G171V mutation in the low density lipoprotein receptor-related protein 5 (LRP5) leads to a high bone mass (HBM) phenotype. Studies using an HBM transgenic mouse model have consistently found increased bone mass and whole-bone strength, but little attention has been paid to bone matrix quality. The current study sought to determine if the cortical bone matrix composition differs in HBM and wild-type mice and to determine how much of the variance in bone material properties is explained by variance in matrix composition. Consistent with previous studies, HBM mice had greater cortical area, moment of inertia, ultimate force, bendingmore » stiffness, and energy to failure than wild-type animals. Interestingly, the increased energy to failure was primarily caused by a large increase in post-yield behavior, with no difference in pre-yield behavior. The HBM mice had increased mineral-to-matrix and collagen cross-link ratios, and decreased crystallinity and carbonate substitution, but no differences in crystal length, intra-fibular strains, and mineral spacing compared to wild-type controls. The largest difference in material properties was a 2-fold increase in the modulus of toughness in HBM mice. Step-wise regression analyses found weak correlations between matrix composition and material properties, and interestingly, the matrix compositional parameters associated with the material properties varied between the wild-type and HBM genotypes. Although the mechanisms controlling the paradoxical combination of more mineralized yet tougher bone in HBM mice remain to be fully explained, the findings suggest that LRP5 represents a target to not only build greater bone quantity, but also to improve bone quality.« less

HBM Mice Have Altered Bone Matrix Composition And Improved Material Toughness

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ross, Ryan D.; Mashiatulla, Maleeha; Acerbo, Alvin S.

Here, the G171V mutation in the low density lipoprotein receptor-related protein 5 (LRP5) leads to a high bone mass (HBM) phenotype. Studies using an HBM transgenic mouse model have consistently found increased bone mass and whole-bone strength, but little attention has been paid to bone matrix quality. The current study sought to determine if the cortical bone matrix composition differs in HBM and wild-type mice and to determine how much of the variance in bone material properties is explained by variance in matrix composition. Consistent with previous studies, HBM mice had greater cortical area, moment of inertia, ultimate force, bendingmore » stiffness, and energy to failure than wild-type animals. Interestingly, the increased energy to failure was primarily caused by a large increase in post-yield behavior, with no difference in pre-yield behavior. The HBM mice had increased mineral-to-matrix and collagen cross-link ratios, and decreased crystallinity and carbonate substitution, but no differences in crystal length, intra-fibular strains, and mineral spacing compared to wild-type controls. The largest difference in material properties was a 2-fold increase in the modulus of toughness in HBM mice. Step-wise regression analyses found weak correlations between matrix composition and material properties, and interestingly, the matrix compositional parameters associated with the material properties varied between the wild-type and HBM genotypes. Although the mechanisms controlling the paradoxical combination of more mineralized yet tougher bone in HBM mice remain to be fully explained, the findings suggest that LRP5 represents a target to not only build greater bone quantity, but also to improve bone quality.« less

3D printing of tissue-simulating phantoms as a traceable standard for biomedical optical measurement

NASA Astrophysics Data System (ADS)

Dong, Erbao; Wang, Minjie; Shen, Shuwei; Han, Yilin; Wu, Qiang; Xu, Ronald

2016-01-01

Optical phantoms are commonly used to validate and calibrate biomedical optical devices in order to ensure accurate measurement of optical properties in biological tissue. However, commonly used optical phantoms are based on homogenous materials that reflect neither optical properties nor multi-layer heterogeneities of biological tissue. Using these phantoms for optical calibration may result in significant bias in biological measurement. We propose to characterize and fabricate tissue simulating phantoms that simulate not only the multi-layer heterogeneities but also optical properties of biological tissue. The tissue characterization module detects tissue structural and functional properties in vivo. The phantom printing module generates 3D tissue structures at different scales by layer-by-layer deposition of phantom materials with different optical properties. The ultimate goal is to fabricate multi-layer tissue simulating phantoms as a traceable standard for optimal calibration of biomedical optical spectral devices.

Characterization of Meta-Materials Using Computational Electromagnetic Methods

NASA Technical Reports Server (NTRS)

Deshpande, Manohar; Shin, Joon

2005-01-01

An efficient and powerful computational method is presented to synthesize a meta-material to specified electromagnetic properties. Using the periodicity of meta-materials, the Finite Element Methodology (FEM) is developed to estimate the reflection and transmission through the meta-material structure for a normal plane wave incidence. For efficient computations of the reflection and transmission over a wide band frequency range through a meta-material a Finite Difference Time Domain (FDTD) approach is also developed. Using the Nicholson-Ross method and the Genetic Algorithms, a robust procedure to extract electromagnetic properties of meta-material from the knowledge of its reflection and transmission coefficients is described. Few numerical examples are also presented to validate the present approach.

Influences on particle shape in underwater pelletizing processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kast, O., E-mail: oliver.kast@ikt.uni-stuttgart.de, E-mail: matthias.musialek@ikt.uni-stuttgart.de, E-mail: kalman.geiger@ikt.uni-stuttgart.de, E-mail: christian.bonten@ikt.uni-stuttgart.de; Musialek, M., E-mail: oliver.kast@ikt.uni-stuttgart.de, E-mail: matthias.musialek@ikt.uni-stuttgart.de, E-mail: kalman.geiger@ikt.uni-stuttgart.de, E-mail: christian.bonten@ikt.uni-stuttgart.de; Geiger, K., E-mail: oliver.kast@ikt.uni-stuttgart.de, E-mail: matthias.musialek@ikt.uni-stuttgart.de, E-mail: kalman.geiger@ikt.uni-stuttgart.de, E-mail: christian.bonten@ikt.uni-stuttgart.de

2014-05-15

Underwater pelletizing has gained high importance within the last years among the different pelletizing technologies, due to its advantages in terms of throughput, automation, pellet quality and applicability to a large variety of thermoplastics. The resulting shape and quality of pellets, however, differ widely, depending on material characteristics and effects not fully understood yet. In an experimental set-up, pellets of different volumes and shapes were produced and the medium pellet mass, the pellet surface and the bulk density were analyzed in order to identify the influence of material properties and process parameters. Additionally, the shaping kinetics at the die openingmore » were watched with a specially developed camera system. It was found that rheological material properties correlate with process parameters and resulting particle form in a complex way. Higher cutting speeds were shown to have a deforming influence on the pellets, leading to less spherical s and lower bulk densities. More viscous materials, however, showed a better resistance against this. Generally, the viscous properties of polypropylene proofed to be dominant over the elastic ones in regard to their influence on pellet shape. It was also shown that the shapes filmed at the die opening and the actual form of the pellets after a cooling track do not always correlate, indicating a significant influence of thermodynamic properties during the cooling.« less

Bone strength in pure bending: bearing of geometric and material properties.

PubMed

Winter, Werner

2008-01-01

Osteoporosis is characterized by decreasing of bone mass and bone strength with advanced age. For characterization of material properties of dense and cellular bone the volumetric bone mineral density (vBMD) is one of the most important contributing factors to bone strength. Often bending tests of whole bone are used to get information about the state of osteoporosis. In a first step, different types of cellular structures are considered to characterize vBMD and its influence to elastic and plastic material properties. Afterwards, the classical theory of plastic bending is used to describe the non-linear moment-curvature relation of a whole bone. For bending of whole bone with sandwich structure an effective second moment of area can be defined. The shape factor as a pure geometrical value is considered to define bone strength. This factor is discussed for a bone with circular cross section and different thickness of cortical bone. The deduced relations and the decrease of material properties are used to demonstrate the influence of osteoporosis to bone bending strength. It can be shown that the elastic and plastic material properties of bone are related to a relative bone mineral density. Starting from an elastic-plastic bone behavior with an constant yield stress the non-linear moment-curvature relation in bending is related to yielding of the fibres in the cross section. The ultimate moment is characterized by a shape factor depending on the geometry of the cross section and on the change of cortical thickness.

Influence of C-H···O Hydrogen Bonds on Macroscopic Properties of Supramolecular Assembly.

PubMed

Ji, Wei; Liu, Guofeng; Li, Zijian; Feng, Chuanliang

2016-03-02

For CH···O hydrogen bonds in assembled structures and the applications, one of the critical issues is how molecular spatial structures affect their interaction modes as well as how to translate the different modes into the macroscopic properties of materials. Herein, coumarin-derived isomeric hydrogelators with different spatial structures are synthesized, where only nitrogen atoms locate at the ortho, meso, or para position in the pyridine ring. The gelators can self-assemble into single crystals and nanofibrous networks through CH···O interactions, which are greatly influenced by nitrogen spatial positions in the pyridine ring, leading to the different self-assembly mechanisms, packing modes, and properties of the nanofibrous networks. Typically, different cell proliferation rates are obtained on the different CH···O bonds driving nanofibrous structures, implying that tiny variation of the stereo-position of nitrogen atoms can be sensitively detected by cells. The study paves a novel way to investigate the influence of isomeric molecular assembly on macroscopic properties and functions of materials.

Multiparameter magnetic inspection system with magnetic field control and plural magnetic transducers

DOEpatents

Jiles, D.C.

1991-04-16

A multiparameter magnetic inspection system is disclosed for providing an efficient and economical way to derive a plurality of independent measurements regarding magnetic properties of the magnetic material under investigation. The plurality of transducers for a plurality of different types of measurements operatively connected to the specimen. The transducers are in turn connected to analytical circuits for converting transducer signals to meaningful measurement signals of the magnetic properties of the specimen. The measurement signals are processed and can be simultaneously communicated to a control component. The measurement signals can also be selectively plotted against one another. The control component operates the functioning of the analytical circuits and operates and controls components to impose magnetic fields of desired characteristics upon the specimen. The system therefore allows contemporaneous or simultaneous derivation of the plurality of different independent magnetic properties of the material which can then be processed to derive characteristics of the material. 1 figure.

Effect of Chemical Treatments on Flax Fibre Reinforced Polypropylene Composites on Tensile and Dome Forming Behaviour

PubMed Central

Wang, Wentian; Lowe, Adrian; Kalyanasundaram, Shankar

2015-01-01

Tensile tests were performed on two different natural fibre composites (same constituent material, similar fibre fraction and thickness but different weave structure) to determine changes in mechanical properties caused by various aqueous chemical treatments and whether any permanent changes remain on drying. Scanning electronic microscopic examinations suggested that flax fibres and the flax/polypropylene interface were affected by the treatments resulting in tensile property variations. The ductility of natural fibre composites was improved significantly under wet condition and mechanical properties (elongation-to-failure, stiffness and strength) can almost retain back to pre-treated levels when dried from wet condition. Preheating is usually required to improve the formability of material in rapid forming, and the chemical treatments performed in this study were far more effective than preheating. The major breakthrough in improving the formability of natural fibre composites can aid in rapid forming of this class of material system. PMID:25789505

Tailoring Heterovalent Interface Formation with Light

DOE PAGES

Park, Kwangwook; Alberi, Kirstin

2017-08-17

Integrating different semiconductor materials into an epitaxial device structure offers additional degrees of freedom to select for optimal material properties in each layer. However, interface between materials with different valences (i.e. III-V, II-VI and IV semiconductors) can be difficult to form with high quality. Using ZnSe/GaAs as a model system, we explore the use of UV illumination during heterovalent interface growth by molecular beam epitaxy as a way to modify the interface properties. We find that UV illumination alters the mixture of chemical bonds at the interface, permitting the formation of Ga-Se bonds that help to passivate the underlying GaAsmore » layer. Illumination also helps to reduce defects in the ZnSe epilayer. Furthermore, these results suggest that moderate UV illumination during growth may be used as a way to improve the optical properties of both the GaAs and ZnSe layers on either side of the interface.« less

The Layer of Kevlar Angle-interlock Woven Fabric Effect on the Tensile Properties of Composite Materials

NASA Astrophysics Data System (ADS)

Xie, Wan-Chen; Guo, Xu-Yi; Yan, Tao; Zhang, Shang-Yong

2017-09-01

This article is based on the structure of three-dimensional angle-interlock longitudinal.The 3-layer, 5-layer, 7-layer and 9-layer of angle-interlock 3D fabrics are woven on sample weaving machine respectively with the 1500D Kevlar fiber twist filament produced by United States DuPont. At the same time, Kevlar plain weave fabric is woven, and three, five, seven and nine layers’ fabric are to be compared. In the process of VARTM composite technology, epoxy resin is matrix material, acetone is diluent, triethylene tetramine is curing agent and the five different fabrics are the reinforced materials respectively. Finally, eight different three-dimensional woven fabric composites were prepared. In this paper, the tensile properties of eight kinds of three-dimensional woven fabric composites were tested respectively.Finally, it is concluded that the five-layer angle-interlock woven fabric prepared by Kevlar fiber shows the best tensile property.

Multiparameter magnetic inspection system with magnetic field control and plural magnetic transducers

DOEpatents

Jiles, David C.

1991-04-16

A multiparameter magnetic inspection system for providing an efficient and economical way to derive a plurality of independent measurements regarding magnetic properties of the magnetic material under investigation. The plurality of transducers for a plurality of different types of measurements operatively connected to the specimen. The transducers are in turn connected to analytical circuits for converting transducer signals to meaningful measurement signals of the magnetic properties of the specimen. The measurement signals are processed and can be simultaneously communicated to a control component. The measurement signals can also be selectively plotted against one another. The control component operates the functioning of the analytical circuits and operates and controls components to impose magnetic fields of desired characteristics upon the specimen. The system therefore allows contemporaneous or simultaneous derivation of the plurality of different independent magnetic properties of the material which can then be processed to derive characteristics of the material.

Effect of stearic acid modified HAp nanoparticles in different solvents on the properties of Pickering emulsions and HAp/PLLA composites.

PubMed

Zhang, Ming; Wang, Ai-Juan; Li, Jun-Ming; Song, Na

2017-10-01

Stearic acid (Sa) was used to modify the surface properties of hydroxyapatite (HAp) in different solvents (water, ethanol or dichloromethane(CH 2 Cl 2 )). Effect of different solvents on the properties of HAp particles (activation ratio, grafting ratio, chemical properties), emulsion properties (emulsion stability, emulsion type, droplet morphology) as well as the cured materials (morphology, average pore size) were studied. FT-IR and XPS results confirmed the interaction occurred between stearic acid and HAp particles. Stable O/W and W/O type Pickering emulsions were prepared using unmodified and Sa modified HAp nanoparticles respectively, which indicated a catastrophic inversion of the Pickering emulsion happened possibly because of the enhanced hydrophobicity of HAp particles after surface modification. Porous materials with different structures and pore sizes were obtained using Pickering emulsion as the template via in situ evaporation solvent method. The results indicated the microstructures of cured samples are different form each other when HAp was surface modified in different solvents. HAp particles fabricated using ethanol as solvent has higher activation ratio and grafting ratio. Pickering emulsion with higher stability and cured porous materials with uniform morphology were obtained compared with samples prepared using water and CH 2 Cl 2 as solvents. In conclusion, surface modification of HAp in different solvents played a very important role for its stabilized Pickering emulsion as well as the microstructure of cured samples. It is better to use ethanol as the solvent for Sa modified HAp particles, which could increase the stability of Pickering emulsion and obtain cured samples with uniform pore size. Copyright © 2017 Elsevier B.V. All rights reserved.

Ceramic Nanocomposites from Tailor-Made Preceramic Polymers

PubMed Central

Mera, Gabriela; Gallei, Markus; Bernard, Samuel; Ionescu, Emanuel

2015-01-01

The present Review addresses current developments related to polymer-derived ceramic nanocomposites (PDC-NCs). Different classes of preceramic polymers are briefly introduced and their conversion into ceramic materials with adjustable phase compositions and microstructures is presented. Emphasis is set on discussing the intimate relationship between the chemistry and structural architecture of the precursor and the structural features and properties of the resulting ceramic nanocomposites. Various structural and functional properties of silicon-containing ceramic nanocomposites as well as different preparative strategies to achieve nano-scaled PDC-NC-based ordered structures are highlighted, based on selected ceramic nanocomposite systems. Furthermore, prospective applications of the PDC-NCs such as high-temperature stable materials for thermal protection systems, membranes for hot gas separation purposes, materials for heterogeneous catalysis, nano-confinement materials for hydrogen storage applications as well as anode materials for secondary ion batteries are introduced and discussed in detail. PMID:28347023

New Polymer Materials for the Laser Sintering Process: Polypropylene and Others

NASA Astrophysics Data System (ADS)

Wegner, Andreas

Laser sintering of polymers gets more and more importance for small series production. However, there is only a little number of materials available for the process. In most cases parts are build up using polyamide 12 or polyamide 11. Reasons for that are high prices, a restricted availability, poor mechanical part properties or an insufficient understanding of the processing of other materials. These problems result from the complex processing conditions in laser sintering with high requirements on the material's characteristics. Within this area, at the chair for manufacturing technology fundamental knowledge was established. Aim of the presented study was to qualify different polymers for the laser sintering process. Polyethylene, polypropylene, polyamide 6, polyoxymethylene as well as polybutylene terephthalate were analyzed. Within the study problems of qualifying new materials are discussed using some examples. Furthermore, the processing conditions as well as mechanical properties of a new polypropylene compound are shown considering also different laser sintering machines.

Ultra-High Temperature Materials Characterization for Propulsion Applications

NASA Technical Reports Server (NTRS)

Rogers, Jan; Hyers, Robert

2007-01-01

Propulsion system efficiency increases as operating temperatures are increased. Some very high-temperature materials are being developed, including refractory metal alloys, carbides, borides, and silicides. System design requires data for materials properties at operating temperatures. Materials property data are not available for many materials of interest at the desired operating temperatures (up to approx. 3000 K). The objective of this work is to provide important physical property data at ultra-high temperatures. The MSFC Electrostatic levitation (ESL) facility can provide measurements of thermophysical properties which include: creep strength, density and thermal expansion for materials being developed for propulsion applications. The ESL facility uses electrostatic fields to position samples between electrodes during processing and characterization studies. Because the samples float between the electrodes during studies, they are free from any contact with a container or test apparatus. This provides a high purity environment for the study of high-temperature, reactive materials. ESL can be used to process a wide variety of materials including metals, alloys, ceramics, glasses and semiconductors. The MSFC ESL has provided non-contact measurements of properties of materials up to 3400 C. Density and thermal expansion are measured by analyzing digital images of the sample at different temperatures. Our novel, non-contact method for measuring creep uses rapid rotation to deform the sample. Digital images of the deformed samples are analyzed to obtain the creep properties, which match those obtained using ASTM Standard E-139 for Nb at 1985 C. Data from selected ESL-based characterization studies will be presented. The ESL technique could support numerous propulsion technologies by advancing the knowledge base and the technology readiness level for ultra-high temperature materials. Applications include non-eroding nozzle materials and lightweight, high-temperature alloys for turbines and structures.

Structural properties of TiO2 nanomaterials

NASA Astrophysics Data System (ADS)

Kusior, Anna; Banas, Joanna; Trenczek-Zajac, Anita; Zubrzycka, Paulina; Micek-Ilnicka, Anna; Radecka, Marta

2018-04-01

The surface of solids is characterized by active, energy-rich sites that determine physicochemical interaction with gaseous and liquid media and possible applications in photocatalysis. The behavior of materials in such processes is related to their form and amount of various species, especially water and forms of oxygen adsorbed on the surface. The preparation of materials with controlled morphology, which includes modifications of the size, geometry, and composition, is currently an important way of optimizing properties, as many of them depend on not only the size and phase composition, but also on shape. Hydroxylated centers on the surface, which can be treated as trapping sites, are particularly significant. Water adsorbed on the surface bridging hydroxyl groups can distinctly modulate the properties of the surface of titania. The saturation of the surface with hydroxyl groups may improve the photocatalytic properties. TiO2 nanomaterials were obtained via different methods. SEM and TEM analysis were performed to study the morphology. The analysis of XRD and Raman data revealed a phase composition of obtained materials. To examine the surface properties, FTIR absorption spectra of TiO2 nanomaterials were recorded. The photocatalytic activity of titanium dioxide nanoparticles was investigated through the decomposition of methylene blue. It was demonstrated that each surface modification affects the amount of adsorbed hydroxyl groups. The different contributions of the two species to the ν(H2O) FTIR bands for different nanostructures result from the preparation conditions. It was noted that pre-adsorbed water (the surface-bridging hydroxyl) might significantly modulate the surface properties of the material. The increase in hydroxyl group density on the titanium dioxide surface enhances the effectiveness of the photocatalytic processes. It was demonstrated that flower-like titania obtained via hydrothermal synthesis exhibits the weakest catalytic activity, in contrast to the typical spherical TiO2.

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.

Stochasticity of bacterial attachment and its predictability by the extended derjaguin-landau-verwey-overbeek theory.

PubMed

Chia, Teck Wah R; Nguyen, Vu Tuan; McMeekin, Thomas; Fegan, Narelle; Dykes, Gary A

2011-06-01

Bacterial attachment onto materials has been suggested to be stochastic by some authors but nonstochastic and based on surface properties by others. We investigated this by attaching pairwise combinations of two Salmonella enterica serovar Sofia (S. Sofia) strains (with different physicochemical and attachment properties) with one strain each of S. enterica serovar Typhimurium, S. enterica serovar Infantis, or S. enterica serovar Virchow (all with similar physicochemical and attachment abilities) in ratios of 0.428, 1, and 2.333 onto glass, stainless steel, Teflon, and polysulfone. Attached bacterial cells were recovered and counted. If the ratio of attached cells of each Salmonella serovar pair recovered was the same as the initial inoculum ratio, the attachment process was deemed stochastic. Experimental outcomes from the study were compared to those predicted by the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory. Significant differences (P < 0.05) between the initial and the attached ratios for serovar pairs containing S. Sofia S1296a for all different ratios were apparent for all materials. For S. Sofia S1635-containing pairs, 7 out of 12 combinations of serovar pairs and materials had attachment ratios not significantly different (P > 0.05) from the initial ratio of 0.428. Five out of 12 and 10 out of 12 samples had attachment ratios not significantly different (P > 0.05) from the initial ratios of 1 and 2.333, respectively. These results demonstrate that bacterial attachment to different materials is likely to be nonstochastic only when the key physicochemical properties of the bacteria were significantly different (P < 0.05) from each other. XDLVO theory could successfully predict the attachment of some individual isolates to particular materials but could not be used to predict the likelihood of stochasticity in pairwise attachment experiments.

Tunable mesoporous bilayer photonic resins with chiral nematic structures and actuator properties.

PubMed

Khan, Mostofa K; Hamad, Wadood Y; Maclachlan, Mark J

2014-04-16

Chiral nematic structures with different helical pitch from layer to layer are embedded into phenol-formaldehyde bilayer resin composite films using cellulose nanocrystals (CNCs) as templates. Selective removal of CNCs results in mesoporous resins with different pore size and helical pitch between the layers. Consequently, these materials exhibit photonic properties by selectively reflecting lights of two different wavelengths and concomitant actuation properties. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Correlation of Critical Temperatures and Electrical Properties in Titanium Films

NASA Astrophysics Data System (ADS)

Gandini, C.; Lacquaniti, V.; Monticone, E.; Portesi, C.; Rajteri, M.; Rastello, M. L.; Pasca, E.; Ventura, G.

Recently transition-edge sensors (TES) have obtained an increasing interest as light detectors due to their high energy resolution and broadband response. Titanium (Ti), with transition temperature up to 0.5 K, is among the suitable materials for TES application. In this work we investigate Ti films obtained from two materials of different purity deposited by e-gun on silicon nitride. Films with different thickness and deposition substrate temperature have been measured. Critical temperatures, electrical resistivities and structural properties obtained from x-ray are related to each other.

Methods and apparatus for moving and separating materials exhibiting different physical properties

DOEpatents

Peterson, Stephen C.; Brimhall, Owen D.; McLaughlin, Thomas J.; Baker, Charles D.; Sparks, Sam L.

1988-01-01

Methods and apparatus for controlling the movement of materials having different physical properties when one of the materials is a fluid. The invention does not rely on flocculation, sedimentation, centrifugation, the buoyancy of the materials, or any other gravity dependent characteristic, in order to achieve its desired results. The methods of the present invention provide that a first acoustic wave is progpagated through a vessel containing the materials. A second acoustic wave, at a frequency different than the first acoustic wave, is also propagated through the vessel so that the two acoustic waves are superimposed upon each other. The superimposition of the two waves creates a beat frequency wave. The beat frequency wave comprises pressure gradients dividing regions of maximum and minimum pressure. The pressure gradients and the regions of maximum and minimum pressure move through space and time at a group velocity. The moving pressure gradients and regions of maximum and minimum pressure act upon the marterials so as to move one of the materials towards a predetermined location in the vessel. The present invention provides that the materials may be controllably moved toward a location, aggreated at a particular location, or physically separated from each other.

The Characteristic Dimensions of the Nanoworld

ERIC Educational Resources Information Center

Wautelet, M.; Duvivier, D.

2007-01-01

Nanoscience is defined as the study of phenomena and manipulation of materials at atomic, molecular and macromolecular scales, where properties differ significantly from those at larger scale. It is the aim of this paper to examine the characteristic dimensions for which the properties of nanosystems differ significantly from those at a larger…

Possibilities for specific utilization of material properties for an optimal part design

NASA Astrophysics Data System (ADS)

Beier, T.; Gerlach, J.; Roettger, R.; Kuhn, P.

2017-09-01

High-strength, cold-formable steels offer great potential for meeting cost and safety requirements in the automotive industry. In view of strengths of up to 1200 MPa now attainable, certain aspects need to be analysed and evaluated in advance in the development process using these materials. In addition to early assessment of crash properties, it is also highly important to adapt the forming process to match the material potential. The steel making companies have widened their portfolios of cold-rolled dual-phase steels well beyond the conventional high-strength steels. There are added new grades which offer a customized selection of high energy absorption, deformation resistance or enhanced cold-forming properties. In this article the necessary components for material modelling for finite element simulation are discussed. Additionally the required tests for material model calibration are presented and the potentials of the thyssenkrupp Steel material data base are introduced. Besides classical tensile tests at different angles to rolling direction and the forming limit curve, the hydraulic bulge test is now available for a wide range of modern steel grades. Using the conventional DP-K®60/98 and the DP-K®700Y980T with higher yield strength the method for calibrating yield locus, hardening and formability is given. With reference to the examples of an A-pillar reinforcement and different crash tests the procedure is shown how the customer can evaluate an optimal steel grade for specific requirements. Although the investigated materials have different yield strengths, no large differences in the forming process between the two steel grades can be found. However some advantages of the high-yield grade can be detected in crash performance depending on the specific boundary and loading conditions.

Mechanical enhancement and in vitro biocompatibility of nanofibrous collagen-chitosan scaffolds for tissue engineering.

PubMed

Zou, Fengjuan; Li, Runrun; Jiang, Jianjun; Mo, Xiumei; Gu, Guofeng; Guo, Zhongwu; Chen, Zonggang

2017-12-01

The collagen-chitosan complex with a three-dimensional nanofiber structure was fabricated to mimic native ECM for tissue repair and biomedical applications. Though the three-dimensional hierarchical fibrous structures of collagen-chitosan composites could provide more adequate stimulus to facilitate cell adhesion, migrate and proliferation, and thus have the potential as tissue engineering scaffolding, there are still limitations in their applications due to the insufficient mechanical properties of natural materials. Because poly (vinyl alcohol) (PVA) and thermoplastic polyurethane (TPU) as biocompatible synthetic polymers can offer excellent mechanical properties, they were introduced into the collagen-chitosan composites to fabricate the mixed collagen/chitosan/PVA fibers and a sandwich structure (collagen/chitosan-TPU-collagen/chitosan) of nanofiber in order to enhance the mechanical properties of the nanofibrous collagen-chitosan scaffold. The results showed that the tensile behavior of materials was enhanced to different degrees with the difference of collagen content in the fibers. Besides the Young's modulus had no obvious changes, both the break strength and the break elongation of materials were heightened after reinforced by PVA. For the collagen-chitosan nanofiber reinforced by TPU, both the break strength and the Young's modulus of materials were heightened in different degrees with the variety of collagen content in the fibers despite the decrease of the break elongation of materials to some extent. In vitro cell test demonstrated that the materials could provide adequate environment for cell adhesion and proliferation. All these indicated that the reinforced collagen-chitosan nanofiber could be as potential scaffold for tissue engineering according to the different mechanical requirements in clinic.

Preparation of a Carbon Doped Tissue-Mimicking Material with High Dielectric Properties for Microwave Imaging Application

PubMed Central

Lan, Siang-Wen; Weng, Min-Hang; Yang, Ru-Yuan; Chang, Shoou-Jinn; Chung, Yaoh-Sien; Yu, Tsung-Chih; Wu, Chun-Sen

2016-01-01

In this paper, the oil-in-gelatin based tissue-mimicking materials (TMMs) doped with carbon based materials including carbon nanotube, graphene ink or lignin were prepared. The volume percent for gelatin based mixtures and oil based mixtures were both around 50%, and the doping amounts were 2 wt %, 4 wt %, and 6 wt %. The effect of doping material and amount on the microwave dielectric properties including dielectric constant and conductivity were investigated over an ultra-wide frequency range from 2 GHz to 20 GHz. The coaxial open-ended reflection technology was used to evaluate the microwave dielectric properties. Six measured values in different locations of each sample were averaged and the standard deviations of all the measured dielectric properties, including dielectric constant and conductivity, were less than one, indicating a good uniformity of the prepared samples. Without doping, the dielectric constant was equal to 23 ± 2 approximately. Results showed with doping of carbon based materials that the dielectric constant and conductivity both increased about 5% to 20%, and the increment was dependent on the doping amount. By proper selection of doping amount of the carbon based materials, the prepared material could map the required dielectric properties of special tissues. The proposed materials were suitable for the phantom used in the microwave medical imaging system. PMID:28773678

Effect of crystallographic orientations of grains on the global mechanical properties of steel sheets by depth sensing indentation

NASA Astrophysics Data System (ADS)

Burik, P.; Pesek, L.; Kejzlar, P.; Andrsova, Z.; Zubko, P.

2017-01-01

The main idea of this work is using a physical model to prepare a virtual material with required properties. The model is based on the relationship between the microstructure and mechanical properties. The macroscopic (global) mechanical properties of steel are highly dependent upon microstructure, crystallographic orientation of grains, distribution of each phase present, etc... We need to know the local mechanical properties of each phase separately in multiphase materials. The grain size is a scale, where local mechanical properties are responsible for the behavior. Nanomechanical testing using depth sensing indentation (DSI) provides a straightforward solution for quantitatively characterizing each of phases in microstructure because it is very powerful technique for characterization of materials in small volumes. The aim of this experimental investigation is: (i) to prove how the mixing rule works for local mechanical properties (indentation hardness HIT) in microstructure scale using the DSI technique on steel sheets with different microstructure; (ii) to compare measured global properties with properties achieved by mixing rule; (iii) to analyze the effect of crystallographic orientations of grains on the mixing rule.

Imaginary refractive index and other microphysical properties of volcanic ash, Sarahan dust, and other mineral aerosols

NASA Astrophysics Data System (ADS)

Rocha Lima, A.; Martins, J.; Krotkov, N. A.; Artaxo, P.; Todd, M.; Ben Ami, Y.; Dolgos, G.; Espinosa, R.

2013-12-01

Aerosol properties are essential to support remote sensing measurements, atmospheric circulation and climate models. This research aims to improve the understanding of the optical and microphysical properties of different types of aerosols particles. Samples of volcanic ash, Saharan dust and other mineral aerosols particles were analyzed by different techniques. Ground samples were sieved down to 45um, de-agglomerated and resuspended in the laboratory using a Fluidized Bed Aerosol Generator (FBAG). Particles were collected on Nuclepore filters into PM10, PM2.5, or PM1.0. and analyzed by different techniques, such as Scanning Electron Microscopy (SEM) for determination of size distribution and shape, spectral reflectance for determination of the optical absorption properties as a function of the wavelength, material density, and X-Ray fluorescence for the elemental composition. The spectral imaginary part of refractive index from the UV to the short wave infrared (SWIR) wavelength was derived empirically from the measurements of the spectral mass absorption coefficient, size distribution and density of the material. Some selected samples were also analyzed with the Polarized Imaging Nephelometer (PI-Neph) instrument for the characterization of the aerosol polarized phase function. This work compares results of the spectral refractive index of different materials obtained by our methodology with those available in the literature. In some cases there are significant differences both in magnitude and spectral dependence of the imaginary refractive index. These differences are evaluated and discussed in this work.

Combinatorial materials synthesis and high-throughput screening: an integrated materials chip approach to mapping phase diagrams and discovery and optimization of functional materials.

PubMed

Xiang, X D

Combinatorial materials synthesis methods and high-throughput evaluation techniques have been developed to accelerate the process of materials discovery and optimization and phase-diagram mapping. Analogous to integrated circuit chips, integrated materials chips containing thousands of discrete different compositions or continuous phase diagrams, often in the form of high-quality epitaxial thin films, can be fabricated and screened for interesting properties. Microspot x-ray method, various optical measurement techniques, and a novel evanescent microwave microscope have been used to characterize the structural, optical, magnetic, and electrical properties of samples on the materials chips. These techniques are routinely used to discover/optimize and map phase diagrams of ferroelectric, dielectric, optical, magnetic, and superconducting materials.

Ultrasonic Data Display and Analysis System Developed (Including Fuzzy Logic Analysis) for the Windows-Based PC

NASA Technical Reports Server (NTRS)

Lovelace, Jeffrey J.; Cios, Kryzsztof J.; Roth, Don J.; cAO, wEI n.

2001-01-01

Post-Scan Interactive Data Display (PSIDD) III is a user-oriented Windows-based system that facilitates the display and comparison of ultrasonic contact measurement data obtained at NASA Glenn Research Center's Ultrasonic Nondestructive Evaluation measurement facility. The system is optimized to compare ultrasonic measurements made at different locations within a material or at different stages of material degradation. PSIDD III provides complete analysis of the primary waveforms in the time and frequency domains along with the calculation of several frequency-dependent properties including phase velocity and attenuation coefficient and several frequency-independent properties, like the cross correlation velocity. The system allows image generation on all the frequency-dependent properties at any available frequency (limited by the bandwidth used in the scans) and on any of the frequency-independent properties. From ultrasonic contact scans, areas of interest on an image can be studied with regard to underlying raw waveforms and derived ultrasonic properties by simply selecting the point on the image. The system offers various modes of indepth comparison between scan points. Up to five scan points can be selected for comparative analysis at once. The system was developed with Borland Delphi software (Visual Pascal) and is based on an SQL data base. It is ideal for the classification of material properties or the location of microstructure variations in materials. Along with the ultrasonic contact measurement software that it is partnered with, this system is technology ready and can be transferred to users worldwide.

Characterizing the temperature dependence of electronic packaging-material properties

NASA Astrophysics Data System (ADS)

Fu, Chia-Yu; Ume, Charles

1995-06-01

A computer-controlled, temperature-dependent material characterization system has been developed for thermal deformation analysis in electronic packaging applications, especially for printed wiring assembly warpage study. For fiberglass-reinforced epoxy (FR-4 type) material, the Young's moduli decrease to as low as 20-30% of the room-temperature values, while the shear moduli decrease to as low as 60-70% of the room-temperature values. The electrical resistance strain gage technique was used in this research. The test results produced overestimated values in property measurements, and this was shown in a case study. A noncontact strau]n measurement technique (laser extensometer) is now being used to measure these properties. Discrepancies of finite-element warpage predictions using different property values increase as the temperature increases from the stress-free temperature.

Thermophysical properties of cement based composites and their changes after artificial ageing

NASA Astrophysics Data System (ADS)

Šín, Peter; Pavlendová, Gabriela; Lukovičová, Jozefa; Kopčok, Michal

2017-07-01

The usage of recycled plastic materials in concrete mix gained increased attention. The behaviour of such environmental friendly material is studied. In this paper an investigation of the thermophysical properties of cement based composites containing plastic waste particles with different percentage is presented. Measurements were carried out using pulse transient method before and after artificial ageing in climatic chamber BINDER MKF (E3).

Life cycle assessment for emerging materials: case study of a garden bed constructed from lumber produced with three different copper treatments

EPA Science Inventory

Although important data and methodological challenges facing LCA and emerging materials exist, this LCA captures material and process changes that are important drivers of environmental impacts. LCA methods need to be amended to reflect properties of emerging materials that deter...

Hook tool manufacture in New Caledonian crows: behavioural variation and the influence of raw materials.

PubMed

Klump, Barbara C; Sugasawa, Shoko; St Clair, James J H; Rutz, Christian

2015-11-18

New Caledonian crows use a range of foraging tools, and are the only non-human species known to craft hooks. Based on a small number of observations, their manufacture of hooked stick tools has previously been described as a complex, multi-stage process. Tool behaviour is shaped by genetic predispositions, individual and social learning, and/or ecological influences, but disentangling the relative contributions of these factors remains a major research challenge. The properties of raw materials are an obvious, but largely overlooked, source of variation in tool-manufacture behaviour. We conducted experiments with wild-caught New Caledonian crows, to assess variation in their hooked stick tool making, and to investigate how raw-material properties affect the manufacture process. In Experiment 1, we showed that New Caledonian crows' manufacture of hooked stick tools can be much more variable than previously thought (85 tools by 18 subjects), and can involve two newly-discovered behaviours: 'pulling' for detaching stems and bending of the tool shaft. Crows' tool manufactures varied significantly: in the number of different action types employed; in the time spent processing the hook and bending the tool shaft; and in the structure of processing sequences. In Experiment 2, we examined the interaction of crows with raw materials of different properties, using a novel paradigm that enabled us to determine subjects' rank-ordered preferences (42 tools by 7 subjects). Plant properties influenced: the order in which crows selected stems; whether a hooked tool was manufactured; the time required to release a basic tool; and, possibly, the release technique, the number of behavioural actions, and aspects of processing behaviour. Results from Experiment 2 suggested that at least part of the natural behavioural variation observed in Experiment 1 is due to the effect of raw-material properties. Our discovery of novel manufacture behaviours indicates a plausible scenario for the evolutionary origins, and gradual refinement, of New Caledonian crows' hooked stick tool making. Furthermore, our experimental demonstration of a link between raw-material properties and aspects of tool manufacture provides an alternative hypothesis for explaining regional differences in tool behaviours observed in New Caledonian crows, and some primate species.

Sensory methods and electronic nose as innovative tools for the evaluation of the aroma transfer properties of food plastic bags.

PubMed

Torri, Luisa; Piochi, Maria

2016-07-01

Despite the key role of the sensory quality for food acceptance, the aroma transfer properties of food packaging materials have not yet been studied using sensory approaches. This research investigated the suitability of sensory and electronic nose methods to evaluate the aroma transfer properties of plastic materials that come in contact with food. Four (W, X, Y, and Z) commercial freezer bags (polyethylene) for domestic uses were compared. The degree of the aroma transfer through the materials was estimated as the sensory contamination of an odor absorber food (bread) by an odor releaser food (onion), separated by the bags and stored under frozen conditions. Bread samples were analyzed by means of an electronic nose, and 42 assessors used three different sensory methods (triangle, scoring, and partial sorted Napping tests). From the triangle test, none of the plastic bags acted as a complete aroma barrier, showing a sensory contamination of bread stored in all four materials. Partial sorting Napping results clearly described the sensory contamination of bread as "onion flavor", due to the aroma transfer from the odor releaser food to the odor absorber food through the plastic bag. Scoring tests showed significant (p<0.0001) differences of aroma transfer properties among the plastic bags, revealing the highest aroma permeation for W (3.1±0.1), the lowest aroma transfer for X and Y (2.0±0.1), and intermediate aroma transfer properties for Z (2.6±0.1). Electronic nose data were in good agreement with the sensory responses, and a high correlation with the scoring data was observed (R 2 =0.988). The presented approaches had suitable results to provide meaningful information on the aroma transfer properties of freezer plastic bags, and could advantageously be applied in the future for analyzing other finished food containers (e.g. plastic trays, boxes, etc.) or packaging materials of a different nature (multilayer plastic films, biodegradable materials, composites, etc.). Copyright © 2016 Elsevier Ltd. All rights reserved.

Qualification Status of Non-Asbestos Internal Insulation in the Reusable Solid Rocket Motor Program

NASA Technical Reports Server (NTRS)

Clayton, Louie

2011-01-01

This paper provides a status of the qualification efforts associated with NASA's RSRMV non-asbestos internal insulation program. For many years, NASA has been actively engaged in removal of asbestos from the shuttle RSRM motors due to occupation health concerns where technicians are working with an EPA banned material. Careful laboratory and subscale testing has lead to the downselect of a organic fiber known as Polybenzimidazol to replace the asbestos fiber filler in the existing synthetic rubber copolymer Nitrile Butadiene - now named PBI/NBR. Manufacturing, processing, and layup of the new material has been a challenge due to the differences in the baseline shuttle RSRM internal insulator properties and PBI/NBR material properties. For this study, data gathering and reduction procedures for thermal and chemical property characterization for the new candidate material are discussed. Difficulties with test procedures, implementation of properties into the Charring Material Ablator (CMA) codes, and results correlation with static motor fire data are provided. After two successful five segment motor firings using the PBI/NBR insulator, performance results for the new material look good and the material should eventually be qualified for man rated use in large solid rocket motor applications.

Use of recycled plastics in concrete: A critical review.

PubMed

Gu, Lei; Ozbakkaloglu, Togay

2016-05-01

Plastics have become an essential part of our modern lifestyle, and the global plastic production has increased immensely during the past 50years. This has contributed greatly to the production of plastic-related waste. Reuse of waste and recycled plastic materials in concrete mix as an environmental friendly construction material has drawn attention of researchers in recent times, and a large number of studies reporting the behavior of concrete containing waste and recycled plastic materials have been published. This paper summarizes the current published literature until 2015, discussing the material properties and recycling methods of plastic and the influence of plastic materials on the properties of concrete. To provide a comprehensive review, a total of 84 studies were considered, and they were classified into sub categories based on whether they dealt with concrete containing plastic aggregates or plastic fibers. Furthermore, the morphology of concrete containing plastic materials is described in this paper to explain the influence of plastic aggregates and plastic fibers on the properties of concrete. The properties of concretes containing virgin plastic materials were also reviewed to establish their similarities and differences with concrete containing recycled plastics. Copyright © 2016 Elsevier Ltd. All rights reserved.

Study on the infrared radiation performance of Tourmaline composite and its effect on the diesel characteristic

NASA Astrophysics Data System (ADS)

Liao, Jian Bin; Yu, Hong Liang; Sun, Di; Ma, Fong Yuan

2017-09-01

The black tourmaline, magnesium tourmaline, and spinel were ground into powder, and the infrared radiation material was prepared by adding the ceramic powder, clay and the other material into the tourmaline powder according to a certain proportion. The infrared radiation property was tested and analyzed, the diesel was infrared radiation activated by the composite material, and the physicochemical property of fuel oil was analyzed pre-test and post-test. The result shows that the infrared absorption spectrum of the black tourmaline of different particle size is stable. After the diesel oil was infrared radiation activated by tourmaline composite materials, the physicochemical property of diesel oil was changed, the activation energy decreased, the viscosity and surface tension of fuel oil were reduced.

Processing and Modeling of Porous Copper Using Sintering Dissolution Process

NASA Astrophysics Data System (ADS)

Salih, Mustafa Abualgasim Abdalhakam

The growth of porous metal has produced materials with improved properties as compared to non-metals and solid metals. Porous metal can be classified as either open cell or closed cell. Open cell allows a fluid media to pass through it. Closed cell is made up of adjacent sealed pores with shared cell walls. Metal foams offer higher strength to weight ratios, increased impact energy absorption, and a greater tolerance to high temperatures and adverse environmental conditions when compared to bulk materials. Copper and its alloys are examples of these, well known for high strength and good mechanical, thermal and electrical properties. In the present study, the porous Cu was made by a powder metallurgy process, using three different space holders, sodium chloride, sodium carbonate and potassium carbonate. Several different samples have been produced, using different ratios of volume fraction. The densities of the porous metals have been measured and compared to the theoretical density calculated using an equation developed for these foams. The porous structure was determined with the removal of spacer materials through sintering process. The sintering process of each spacer material depends on the melting point of the spacer material. Processing, characterization, and mechanical properties were completed. These tests include density measurements, compression tests, computed tomography (CT) and scanning electron microscopy (SEM). The captured morphological images are utilized to generate the object-oriented finite element (OOF) analysis for the porous copper. Porous copper was formed with porosities in the range of 40-66% with density ranges from 3 to 5.2 g/cm3. A study of two different methods to measure porosity was completed. OOF (Object Oriented Finite Elements) is a desktop software application for studying the relationship between the microstructure of a material and its overall mechanical, dielectric, or thermal properties using finite element models based on real or simulated micrographs. OOF provides methods for segmenting images, creating meshes and solving of complex geometries using finite element models, and visualizing 2D results.

Recent Progress on Ferroelectric Polymer-Based Nanocomposites for High Energy Density Capacitors: Synthesis, Dielectric Properties, and Future Aspects.

PubMed

Prateek; Thakur, Vijay Kumar; Gupta, Raju Kumar

2016-04-13

Dielectric polymer nanocomposites are rapidly emerging as novel materials for a number of advanced engineering applications. In this Review, we present a comprehensive review of the use of ferroelectric polymers, especially PVDF and PVDF-based copolymers/blends as potential components in dielectric nanocomposite materials for high energy density capacitor applications. Various parameters like dielectric constant, dielectric loss, breakdown strength, energy density, and flexibility of the polymer nanocomposites have been thoroughly investigated. Fillers with different shapes have been found to cause significant variation in the physical and electrical properties. Generally, one-dimensional and two-dimensional nanofillers with large aspect ratios provide enhanced flexibility versus zero-dimensional fillers. Surface modification of nanomaterials as well as polymers adds flavor to the dielectric properties of the resulting nanocomposites. Nowadays, three-phase nanocomposites with either combination of fillers or polymer matrix help in further improving the dielectric properties as compared to two-phase nanocomposites. Recent research has been focused on altering the dielectric properties of different materials while also maintaining their superior flexibility. Flexible polymer nanocomposites are the best candidates for application in various fields. However, certain challenges still present, which can be solved only by extensive research in this field.

Inducing electric polarization in ultrathin insulating layers

NASA Astrophysics Data System (ADS)

Martinez-Castro, Jose; Piantek, Marten; Persson, Mats; Serrate, David; Hirjibehedin, Cyrus F.

Studies of ultrathin polar oxide films have attracted the interest of researchers for a long time due to their different properties compared to bulk materials. However they present several challenges such as the difficulty in the stabilization of the polar surfaces and the limited success in tailoring their properties. Moreover, recently developed Van der Waals materials have shown that the stacking of 2D-layers trigger new collective states thanks to the interaction between layers. Similarly, interface phenomena emerge in polar oxides, like induced ferroelectricity. This represents a promising way for the creation of new materials with customized properties that differ from those of the isolated layers. Here we present a new approach for the fabrication and study of atomically thin insulating films. We show that the properties of insulating polar layers of sodium chloride (NaCl) can be engineered when they are placed on top of a charge modulated template of copper nitride (Cu2N). STM studies carried out in ultra-high vacuum and at low temperatures over NaCl/Cu2N/Cu(001) show that we are able to build up and stabilize interfaces of polar surface at the limit of one atomic layer showing new properties not present before at the atomic scale.

When biomolecules meet graphene: from molecular level interactions to material design and applications.

PubMed

Li, Dapeng; Zhang, Wensi; Yu, Xiaoqing; Wang, Zhenping; Su, Zhiqiang; Wei, Gang

2016-12-01

Graphene-based materials have attracted increasing attention due to their atomically-thick two-dimensional structures, high conductivity, excellent mechanical properties, and large specific surface areas. The combination of biomolecules with graphene-based materials offers a promising method to fabricate novel graphene-biomolecule hybrid nanomaterials with unique functions in biology, medicine, nanotechnology, and materials science. In this review, we focus on a summarization of the recent studies in functionalizing graphene-based materials using different biomolecules, such as DNA, peptides, proteins, enzymes, carbohydrates, and viruses. The different interactions between graphene and biomolecules at the molecular level are demonstrated and discussed in detail. In addition, the potential applications of the created graphene-biomolecule nanohybrids in drug delivery, cancer treatment, tissue engineering, biosensors, bioimaging, energy materials, and other nanotechnological applications are presented. This review will be helpful to know the modification of graphene with biomolecules, understand the interactions between graphene and biomolecules at the molecular level, and design functional graphene-based nanomaterials with unique properties for various applications.

Investigation of Oxidation Profile in PMR-15 Polyimide using Atomic Microscope (AFM)

NASA Technical Reports Server (NTRS)

Meador, Mary Ann B.; Johnson, Lili L.; Eby, R. K.

2002-01-01

Nanoindentation measurements are made on thermosetting materials using cantiever deflection vs. piezoelectric scanner position behavior determined by AFM. The spring model is used to determine mechanical properties of materials. The generalized Sneddon's equation is utilized to calculate Young's moduli for thermosetting materials at ambient conditions. Our investigations show that the force-penetration depth curves during unloading in these materials can be described accurately by a power law relationship. The results show that the accuracy of the measurements can be controlled within 7%. The above method is used to study oxidation profiles in Pl\\1R-15 polyimide. The thermo-mechanical profiles ofPNIR-15 indicate that the elastic modulus at the surface portion of the specimen is different from that at the interior of the material. It is also shown that there are two zones within the oxidized portion of the samples. Results confirm that the surface layer and the core material have substantially different properties.

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.

Local mechanical properties of LFT injection molded parts: Numerical simulations versus experiments

NASA Astrophysics Data System (ADS)

Desplentere, F.; Soete, K.; Bonte, H.; Debrabandere, E.

2014-05-01

In predictive engineering for polymer processes, the proper prediction of material microstructure from known processing conditions and constituent material properties is a critical step forward properly predicting bulk properties in the finished composite. Operating within the context of long-fiber thermoplastics (LFT, length < 15mm) this investigation concentrates on the prediction of the local mechanical properties of an injection molded part. To realize this, the Autodesk Simulation Moldflow Insight 2014 software has been used. In this software, a fiber breakage algorithm for the polymer flow inside the mold is available. Using well known micro mechanic formulas allow to combine the local fiber length with the local orientation into local mechanical properties. Different experiments were performed using a commercially available glass fiber filled compound to compare the measured data with the numerical simulation results. In this investigation, tensile tests and 3 point bending tests are considered. To characterize the fiber length distribution of the polymer melt entering the mold (necessary for the numerical simulations), air shots were performed. For those air shots, similar homogenization conditions were used as during the injection molding tests. The fiber length distribution is characterized using automated optical method on samples for which the matrix material is burned away. Using the appropriate settings for the different experiments, good predictions of the local mechanical properties are obtained.

Radiation shielding properties of barite coated fabric by computer programme

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akarslan, F.; Molla, T.; Üncü, I. S.

2015-03-30

With the development of technology radiation started to be used in variety of different fields. As the radiation is hazardous for human health, it is important to keep radiation dose as low as possible. This is done mainly using shielding materials. Barite is one of the important materials in this purpose. As the barite is not used directly it can be used in some other materials such as fabric. For this purposes barite has been coated on fabric in order to improve radiation shielding properties of fabric. Determination of radiation shielding properties of coated fabric has been done by usingmore » computer program written C# language. With this program the images obtained from digital Rontgen films is used to determine radiation shielding properties in terms of image processing numerical values. Those values define radiation shielding and in this way the coated barite effect on radiation shielding properties of fabric has been obtained.« less

Laboratory investigations into fracture propagation characteristics of rock material

NASA Astrophysics Data System (ADS)

Prasad, B. N. V. Siva; Murthy, V. M. S. R.

2018-04-01

After Industrial Revolution, demand of materials for building up structures have increased enormously. Unfortunately, failures of such structures resulted in loss of life and property. Rock is anisotropic and discontinuous in nature with inherent flaws or so-called discontinuities in it. Rock is apparently used for construction in mining, civil, tunnelling, hydropower, geothermal and nuclear sectors [1]. Therefore, the strength of the structure built up considering rockmass as the construction material needs proper technical evaluation during designing stage itself to prevent and predict the scenarios of catastrophic failures due to these inherent fractures [2]. In this study, samples collected from nine different drilling sites have been investigated in laboratory for understanding the fracture propagation characteristics in rock. Rock material properties, ultrasonic velocities through pulse transmission technique and Mode I Fracture Toughness Testing of different variants of Dolomites and Graywackes are determined in laboratory and the resistance of the rock material to catastrophic crack extension or propagation has been determined. Based on the Fracture Toughness values and the rock properties, critical Energy Release Rates have been estimated. However further studies in this direction is to be carried out to understand the fracture propagation characteristics in three-dimensional space.

Nonreciprocal optical properties based on magneto-optical materials: n-InAs, GaAs and HgCdTe

NASA Astrophysics Data System (ADS)

Wang, Han; Wu, Hao; Zhou, Jian-qiu

2018-02-01

Compared with reciprocal optical materials, nonreciprocal materials can break the time reversal and detailed balance due to special nonreciprocal effect, while how its characteristics performing on infrared wavelength have not been paid enough attention. In this paper, the optical properties of three magneto-optical materials was investigated in infrared band, that are n-InAs, GaAs, HgCdTe, based on Finite Difference Time Domain (FDTD) method. The equations of dielectric constant tensor are present and the effect of magnetic field intensity and frequency has been studied in detail. Additionally, the effect of incidence angle at positive and negative directions to the nonreciprocal absorptivity is also investigated. It is found that the nonreciprocal effect is obvious in infrared wavelength, and the nonreciprocal effect could adjust the absorption characteristic, thus be able to tune the absorption for the specific frequency of incident light. In addition to modeling the directional radiative properties at various angles of incidence, the absorption peaks of three materials under different incident angles are also calculated to understand the light absorption and to facilitate the optimal design of high-performance photovoltaic and optical instrument.

Effects of La2O3 Content and Rolling on Microstructure and Mechanical Properties of ODS Molybdenum Alloys

NASA Astrophysics Data System (ADS)

Ma, Jingling; Li, Wuhui; Wang, Guangxin; Li, Yaqiong; Guo, Hongbo; Zhao, Zeliang; Li, Wei

2017-10-01

In order to study the effects of La2O3 content and rolling on microstructure and mechanical properties of Mo-La2O3 alloys, Mo-0.5% (1%) La2O3 alloys were prepared by liquid-solid doping technique, subsequently rolled either by a single-direction rolling or a cross-rolling. As a result, three different materials were prepared for this study. After being annealed at 1800 °C, the single-directionally rolled Mo-1% La2O3 alloy shows the best mechanical properties in terms of strength, hardness, and sagging deformation among the three materials. This is attributed to the observation that the alloy is only recovered with a microstructure of subgrains and dislocations. The single-directionally rolled Mo-0.5% La2O3 exhibits the worst mechanical property among the three materials. In this material, coarse grains, but no subgrains and dislocations, can be observed after annealing, indicating that it is fully recrystallized. For the cross-rolled Mo-1% La2O3 alloy, grains of dispersed sizes, but no dislocations, are visible after annealing, implying that this alloy is partially recrystallized. Accordingly, the mechanical property of this material is in between the other two materials. Thus, the mechanical properties of the three materials can be well understood based on OM, SEM, and TEM results. Overall, the single-directionally rolled Mo-1% La2O3 alloy possesses good mechanical properties and is more suitable for high-temperature applications.

Experimental assessment of aggregate surfacing materials.

DOT National Transportation Integrated Search

2007-06-30

"An extensive suite of geotechnical laboratory tests were conducted to quantify differences in : engineering properties of three crushed aggregates commonly used on Montana highway projects. The : material types are identified in the Montana Suppleme...

Mechanical features of various silkworm crystalline considering hydration effect via molecular dynamics simulations.

PubMed

Kim, Yoonjung; Lee, Myeongsang; Choi, Hyunsung; Baek, Inchul; Kim, Jae In; Na, Sungsoo

2018-04-01

Silk materials are receiving significant attention as base materials for various functional nanomaterials and nanodevices, due to its exceptionally high mechanical properties, biocompatibility, and degradable characteristics. Although crystalline silk regions are composed of various repetitive motifs with differing amino acid sequences, how the effect of humidity works differently on each of the motifs and their structural characteristics remains unclear. We report molecular dynamics (MD) simulations on various silkworm fibroins composed of major motifs (i.e. (GAGAGS) n , (GAGAGA) n , and (GAGAGY) n ) at varying degrees of hydration, and reveal how each major motifs of silk fibroins change at each degrees of hydration using MD simulations and their structural properties in mechanical perspective via steered molecular dynamics simulations. Our results explain what effects humidity can have on nanoscale materials and devices consisting of crystalline silk materials.

Reformulating polycaprolactone fumarate to eliminate toxic diethylene glycol: effects of polymeric branching and autoclave sterilization on material properties.

PubMed

Runge, M Brett; Wang, Huan; Spinner, Robert J; Windebank, Anthony J; Yaszemski, Michael J

2012-01-01

Polycaprolactone fumarate (PCLF) is a cross-linkable derivative of polycaprolactone diol that has been shown to be an effective nerve conduit material that supports regeneration across segmental nerve defects and has warranted future clinical trials. Degradation of PCLF (PCLF(DEG)) releases toxic small molecules of diethylene glycol used as the initiator for the synthesis of polycaprolactone diol. In an effort to eliminate this toxic degradation product we present a strategy for the synthesis of PCLF from either propylene glycol (PCLF(PPD)) or glycerol (PCLF(GLY)). PCLF(PPD) is linear and resembles the previously studied PCLF(DEG), while PCLF(GLY) is branched and exhibits dramatically different material properties. The synthesis and characterization of their thermal, rheological, and mechanical properties are reported. The results show that the linear PCLF(PPD) has material properties similar to the previously studied PCLF(DEG). The branched PCLF(GLY) exhibits dramatically lower crystalline properties resulting in lower rheological and mechanical moduli, and is therefore a more compliant material. In addition, the question of an appropriate Food and Drug Administration approvable sterilization method is addressed. This study shows that autoclave sterilization of PCLF materials is an acceptable sterilization method for cross-linked PCLF and has minimal effect on the PCLF thermal and mechanical properties. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

A method for subject-specific modelling and optimisation of the cushioning properties of insole materials used in diabetic footwear.

PubMed

Chatzistergos, Panagiotis E; Naemi, Roozbeh; Chockalingam, Nachiappan

2015-06-01

This study aims to develop a numerical method that can be used to investigate the cushioning properties of different insole materials on a subject-specific basis. Diabetic footwear and orthotic insoles play an important role for the reduction of plantar pressure in people with diabetes (type-2). Despite that, little information exists about their optimum cushioning properties. A new in-vivo measurement based computational procedure was developed which entails the generation of 2D subject-specific finite element models of the heel pad based on ultrasound indentation. These models are used to inverse engineer the material properties of the heel pad and simulate the contact between plantar soft tissue and a flat insole. After its validation this modelling procedure was utilised to investigate the importance of plantar soft tissue stiffness, thickness and loading for the correct selection of insole material. The results indicated that heel pad stiffness and thickness influence plantar pressure but not the optimum insole properties. On the other hand loading appears to significantly influence the optimum insole material properties. These results indicate that parameters that affect the loading of the plantar soft tissues such as body mass or a person's level of physical activity should be carefully considered during insole material selection. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

A novel high-strength and highly corrosive biodegradable Fe-Pd alloy: Structural, mechanical and in vitro corrosion and cytotoxicity study.

PubMed

Čapek, Jaroslav; Msallamová, Šárka; Jablonská, Eva; Lipov, Jan; Vojtěch, Dalibor

2017-10-01

Recently, iron-based materials have been considered as candidates for the fabrication of biodegradable load-bearing implants. Alloying with palladium has been found to be a suitable approach to enhance the insufficient corrosion rate of iron-based alloys. In this work, we have extensively compared the microstructure, the mechanical and corrosion properties, and the cytotoxicity of an FePd2 (wt%) alloy prepared by three different routes - casting, mechanical alloying and spark plasma sintering (SPS), and mechanical alloying and the space holder technique (SHT). The properties of the FePd2 (wt%) were compared with pure Fe prepared in the same processes. The preparation route significantly influenced the material properties. Materials prepared by SPS possessed the highest values of mechanical properties (CYS~750-850MPa) and higher corrosion rates than the casted materials. Materials prepared by SHT contained approximately 60% porosity; therefore, their mechanical properties reached the lowest values, and they had the highest corrosion rates, approximately 0.7-1.2mm/a. Highly porous FePd2 was tested in vitro according to the ISO 10993-5 standard using L929 cells, and two-fold diluted extracts showed acceptable cytocompatibility. In general, alloying with Pd enhanced both mechanical properties and corrosion rates and did not decrease the cytocompatibility of the studied materials. Copyright © 2017 Elsevier B.V. All rights reserved.

Manganese oxides-based composite electrodes for supercapacitors

NASA Astrophysics Data System (ADS)

Su, Dongyun; Ma, Jun; Huang, Mingyu; Liu, Feng; Chen, Taizhou; Liu, Chao; Ni, Hongjun

2017-06-01

In recent, nanostructured transition metal oxides as a new class of energy storage materials have widely attracted attention due to its excellent electrochemical performance for supercapacitors. The MnO2 based transition metal oxides and their composite electrode materials were focused in the review for supercapacitor applications. The researches on different nanostructures of manganese oxides such as Nano rods, Nano sheets, nanowires, nanotubes and so on have been discovered in recent years, together with brief explanations of their properties. Research on enhancing materials’ properties by designing combination of different materials on the micron or Nano scale is too limited, and therefore we discuss the effects of different components’ sizes and their synergy on the performance. Moreover, the low-cost and large-scale fabrication of flexible supercapacitors with high performance (high energy density and cycle stability) have been pointed out and studied.

Full-color tuning in binary polymer:perovskite nanocrystals organic-inorganic hybrid blends

NASA Astrophysics Data System (ADS)

Perulli, A.; Balena, A.; Fernandez, M.; Nedelcu, G.; Cretí, A.; Kovalenko, M. V.; Lomascolo, M.; Anni, M.

2018-04-01

The excellent optical and electronic properties of metal halide perovskites recently proposed these materials as interesting active materials for optoelectronic applications. In particular, the high color purity of perovskite colloidal nanocrystals (NCs) had recently motivated their exploration as active materials for light emitting diodes with tunable emission across the visible range. In this work, we investigated the emission properties of binary blends of conjugated polymers and perovskite NCs. We demonstrate that the emission color of the blends is determined by the superposition of the component photoluminescence spectra, allowing color tuning by acting on the blend relative composition. The use of two different polymers, two different perovskite NCs, and different blend compositions is exploited to tune the blend color in the blue-green, yellow-red, and blue-red ranges, including white light generation.

The effect of solid interaction forces on pneumatic handling of sorbent powders

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, R.J.; Fan, L.S.

1993-06-01

This study shows that a comparison of powder characteristics--particle morphologies, particle size distributions, and static dielectric and Hamaker constants--can be used to interpret differences in dispersion and transport behavior between powders. These differences are attributed to the relative values of the solid-solid interaction forces experience by each powder in the process. The static dielectric constants of the powders are used as the material properties related to the relative magnitudes of the electrostatic forces. Similarly, the Hamaker constants are the material properties used to indicate the relative magnitudes of the van der Waals forces. The effects of differences in particle morphologiesmore » and size distributions are used to evaluate the dispersibility and efficiency of transport of four calcium-based powder materials used as sorbents in flue-gas desulfurization.« less

Viscoelastic properties of dendrimers in the melt from nonequlibrium molecular dynamics

NASA Astrophysics Data System (ADS)

Bosko, Jaroslaw T.; Todd, B. D.; Sadus, Richard J.

2004-12-01

The viscoelastic properties of dendrimers of generation 1-4 are studied using nonequilibrium molecular dynamics. Flow properties of dendrimer melts under shear are compared to systems composed of linear chain polymers of the same molecular weight, and the influence of molecular architecture is discussed. Rheological material properties, such as the shear viscosity and normal stress coefficients, are calculated and compared for both systems. We also calculate and compare the microscopic properties of both linear chain and dendrimer molecules, such as their molecular alignment, order parameters and rotational velocities. We find that the highly symmetric shape of dendrimers and their highly constrained geometry allows for substantial differences in their material properties compared to traditional linear polymers of equivalent molecular weight.

Physicochemical characterization of porcine bone-derived grafting material and comparison with bovine xenografts for dental applications.

PubMed

Lee, Jung Heon; Yi, Gyu Sung; Lee, Jin Woong; Kim, Deug Joong

2017-12-01

The physicochemical properties of a xenograft are very important because they strongly influence the bone regeneration capabilities of the graft material. Even though porcine xenografts have many advantages, only a few porcine xenografts are commercially available, and most of their physicochemical characteristics have yet to be reported. Thus, in this work we aimed to investigate the physicochemical characteristics of a porcine bone grafting material and compare them with those of 2 commercially available bovine xenografts to assess the potential of xenogenic porcine bone graft materials for dental applications. We used various characterization techniques, such as scanning electron microscopy, the Brunauer-Emmett-Teller adsorption method, atomic force microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, and others, to compare the physicochemical properties of xenografts of different origins. The porcine bone grafting material had relatively high porosity (78.4%) and a large average specific surface area (SSA; 69.9 m 2 /g), with high surface roughness (10-point average roughness, 4.47 µm) and sub-100-nm hydroxyapatite crystals on the surface. Moreover, this material presented a significant fraction of sub-100-nm pores, with negligible amounts of residual organic substances. Apart from some minor differences, the overall characteristics of the porcine bone grafting material were very similar to those of one of the bovine bone grafting material. However, many of these morphostructural properties were significantly different from the other bovine bone grafting material, which exhibited relatively smooth surface morphology with a porosity of 62.0% and an average SSA of 0.5 m 2 /g. Considering that both bovine bone grafting materials have been successfully used in oral surgery applications in the last few decades, this work shows that the porcine-derived grafting material possesses most of the key physiochemical characteristics required for its application as a highly efficient xenograft material for bone replacement.

Numerical Characterization of Piezoceramics Using Resonance Curves

PubMed Central

Pérez, Nicolás; Buiochi, Flávio; Brizzotti Andrade, Marco Aurélio; Adamowski, Julio Cezar

2016-01-01

Piezoelectric materials characterization is a challenging problem involving physical concepts, electrical and mechanical measurements and numerical optimization techniques. Piezoelectric ceramics such as Lead Zirconate Titanate (PZT) belong to the 6 mm symmetry class, which requires five elastic, three piezoelectric and two dielectric constants to fully represent the material properties. If losses are considered, the material properties can be represented by complex numbers. In this case, 20 independent material constants are required to obtain the full model. Several numerical methods have been used to adjust the theoretical models to the experimental results. The continuous improvement of the computer processing ability has allowed the use of a specific numerical method, the Finite Element Method (FEM), to iteratively solve the problem of finding the piezoelectric constants. This review presents the recent advances in the numerical characterization of 6 mm piezoelectric materials from experimental electrical impedance curves. The basic strategy consists in measuring the electrical impedance curve of a piezoelectric disk, and then combining the Finite Element Method with an iterative algorithm to find a set of material properties that minimizes the difference between the numerical impedance curve and the experimental one. Different methods to validate the results are also discussed. Examples of characterization of some common piezoelectric ceramics are presented to show the practical application of the described methods. PMID:28787875

Numerical Characterization of Piezoceramics Using Resonance Curves.

PubMed

Pérez, Nicolás; Buiochi, Flávio; Brizzotti Andrade, Marco Aurélio; Adamowski, Julio Cezar

2016-01-27

Piezoelectric materials characterization is a challenging problem involving physical concepts, electrical and mechanical measurements and numerical optimization techniques. Piezoelectric ceramics such as Lead Zirconate Titanate (PZT) belong to the 6 mm symmetry class, which requires five elastic, three piezoelectric and two dielectric constants to fully represent the material properties. If losses are considered, the material properties can be represented by complex numbers. In this case, 20 independent material constants are required to obtain the full model. Several numerical methods have been used to adjust the theoretical models to the experimental results. The continuous improvement of the computer processing ability has allowed the use of a specific numerical method, the Finite Element Method (FEM), to iteratively solve the problem of finding the piezoelectric constants. This review presents the recent advances in the numerical characterization of 6 mm piezoelectric materials from experimental electrical impedance curves. The basic strategy consists in measuring the electrical impedance curve of a piezoelectric disk, and then combining the Finite Element Method with an iterative algorithm to find a set of material properties that minimizes the difference between the numerical impedance curve and the experimental one. Different methods to validate the results are also discussed. Examples of characterization of some common piezoelectric ceramics are presented to show the practical application of the described methods.

Correlation between cavitation erosion resistance and cyclic mechanical properties of different metallic materials

NASA Astrophysics Data System (ADS)

Kaufhold, Corinna; Pöhl, Fabian; Theisen, Werner

2017-05-01

Machine components in contact with flowing fluids are especially prone to cavitation erosion, where plastic deformation and material loss occur due to the repeated implosion of cavitation bubbles in the vicinity of a solid surface. Identifying a correlation between experimentally derivable material properties and resistance against cavitation erosion could help improve the lifetime of cavitation-affected components. Cavitation erosion is a predominantly fatigue-driven phenomenon. In this investigation, we conducted nanoindentation experiments to examine cyclic micromechanical material properties in response to an increasing number of cycles. The experiments were performed on pure iron and different steel grades, i.e., austenitic stainless CrMnCN steels, interstitially alloyed with carbon and nitrogen. We confirmed the view, also proposed in literature, that indentation hardness is inappropriate for ordering the investigated materials by incubation period or maximum erosion rate. We found that the percentage increase of nanoindentation contact stiffness, after an increasing number of cycles, is a promising indicator in terms of the overall ranking of cavitation erosion resistance among the considered materials. Although a single cavitation impact is associated with a significantly higher strain rate than nanoindentation experiments, it is shown that the plastically deformed area around each indent exhibits indications of deformation, such as the formation of slip lines that are also observable after cavitation-induced impacts.

Graphene and its elemental analogue: A molecular dynamics view of fracture phenomenon

NASA Astrophysics Data System (ADS)

Rakib, Tawfiqur; Mojumder, Satyajit; Das, Sourav; Saha, Sourav; Motalab, Mohammad

2017-06-01

Graphene and some graphene like two dimensional materials; hexagonal boron nitride (hBN) and silicene have unique mechanical properties which severely limit the suitability of conventional theories used for common brittle and ductile materials to predict the fracture response of these materials. This study revealed the fracture response of graphene, hBN and silicene nanosheets under different tiny crack lengths by molecular dynamics (MD) simulations using LAMMPS. The useful strength of these two dimensional materials are determined by their fracture toughness. Our study shows a comparative analysis of mechanical properties among the elemental analogues of graphene and suggested that hBN can be a good substitute for graphene in terms of mechanical properties. We have also found that the pre-cracked sheets fail in brittle manner and their failure is governed by the strength of the atomic bonds at the crack tip. The MD prediction of fracture toughness shows significant difference with the fracture toughness determined by Griffth's theory of brittle failure which restricts the applicability of Griffith's criterion for these materials in case of nano-cracks. Moreover, the strengths measured in armchair and zigzag directions of nanosheets of these materials implied that the bonds in armchair direction have the stronger capability to resist crack propagation compared to zigzag direction.

Self-assembled phase-change nanowire for nonvolatile electronic memory

NASA Astrophysics Data System (ADS)

Jung, Yeonwoong

One of the most important subjects in nanosciences is to identify and exploit the relationship between size and structural/physical properties of materials and to explore novel material properties at a small-length scale. Scale-down of materials is not only advantageous in realizing miniaturized devices but nanometer-sized materials often exhibit intriguing physical/chemical properties that greatly differ from their bulk counterparts. This dissertation studies self-assembled phase-change nanowires for future nonvolatile electronic memories, mainly focusing on their size-dependent memory switching properties. Owing to the one-dimensional, unique geometry coupled with the small and tunable sizes, bottom-designed nanowires offer great opportunities in terms for both fundamental science and practical engineering perspectives, which would be difficult to realize in conventional top-down based approaches. We synthesized chalcogenide phase-change nanowires of different compositions and sizes, and studied their electronic memory switching owing to the structural change between crystalline and amorphous phases. In particular, we investigated nanowire size-dependent memory switching parameters, including writing current, power consumption, and data retention times, as well as studying composition-dependent electronic properties. The observed size and composition-dependent switching and recrystallization kinetics are explained based on the heat transport model and heterogeneous nucleation theories, which help to design phase-change materials with better properties. Moreover, we configured unconventional heterostructured phase-change nanowire memories and studied their multiple memory states in single nanowire devices. Finally, by combining in-situ/ex-situ electron microscopy techniques and electrical measurements, we characterized the structural states involved in electrically-driven phase-change in order to understand the atomistic mechanism that governs the electronic memory switching through phase-change.

Machine learning properties of binary wurtzite superlattices

DOE PAGES

Pilania, G.; Liu, X. -Y.

2018-01-12

The burgeoning paradigm of high-throughput computations and materials informatics brings new opportunities in terms of targeted materials design and discovery. The discovery process can be significantly accelerated and streamlined if one can learn effectively from available knowledge and past data to predict materials properties efficiently. Indeed, a very active area in materials science research is to develop machine learning based methods that can deliver automated and cross-validated predictive models using either already available materials data or new data generated in a targeted manner. In the present paper, we show that fast and accurate predictions of a wide range of propertiesmore » of binary wurtzite superlattices, formed by a diverse set of chemistries, can be made by employing state-of-the-art statistical learning methods trained on quantum mechanical computations in combination with a judiciously chosen numerical representation to encode materials’ similarity. These surrogate learning models then allow for efficient screening of vast chemical spaces by providing instant predictions of the targeted properties. Moreover, the models can be systematically improved in an adaptive manner, incorporate properties computed at different levels of fidelities and are naturally amenable to inverse materials design strategies. Finally, while the learning approach to make predictions for a wide range of properties (including structural, elastic and electronic properties) is demonstrated here for a specific example set containing more than 1200 binary wurtzite superlattices, the adopted framework is equally applicable to other classes of materials as well.« less

Machine learning properties of binary wurtzite superlattices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pilania, G.; Liu, X. -Y.

The burgeoning paradigm of high-throughput computations and materials informatics brings new opportunities in terms of targeted materials design and discovery. The discovery process can be significantly accelerated and streamlined if one can learn effectively from available knowledge and past data to predict materials properties efficiently. Indeed, a very active area in materials science research is to develop machine learning based methods that can deliver automated and cross-validated predictive models using either already available materials data or new data generated in a targeted manner. In the present paper, we show that fast and accurate predictions of a wide range of propertiesmore » of binary wurtzite superlattices, formed by a diverse set of chemistries, can be made by employing state-of-the-art statistical learning methods trained on quantum mechanical computations in combination with a judiciously chosen numerical representation to encode materials’ similarity. These surrogate learning models then allow for efficient screening of vast chemical spaces by providing instant predictions of the targeted properties. Moreover, the models can be systematically improved in an adaptive manner, incorporate properties computed at different levels of fidelities and are naturally amenable to inverse materials design strategies. Finally, while the learning approach to make predictions for a wide range of properties (including structural, elastic and electronic properties) is demonstrated here for a specific example set containing more than 1200 binary wurtzite superlattices, the adopted framework is equally applicable to other classes of materials as well.« less

Graphene and Polymer Composites for Supercapacitor Applications: a Review

NASA Astrophysics Data System (ADS)

Gao, Yang

2017-06-01

Supercapacitors, as one of the energy storage devices, exhibit ultrahigh capacitance, high power density, and long cycle. High specific surface area, mechanical and chemical stability, and low cost are often required for supercapacitor materials. Graphene, as a new emerging carbon material, has attracted a lot of attention in energy storage field due to its intrinsic properties. Polymers are often incorporated into graphene for a number of enhanced or new properties as supercapacitors. In this paper, different polymers which are used to form composite materials for supercapacitor applications are reviewed. The functions, strategies, and the enhanced properties of graphene and polymer composites are discussed. Finally, the recent development of graphene and polymers for flexible supercapacitors are also discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hooper, R. J.; Adams, D. P.; Hirschfeld, D.

The rapid release of energy from reactive multilayer foils can create extreme local temperature gradients near substrate materials. To fully exploit the potential of these materials, a better understanding of the interaction between the substrate or filler material and the foil is needed. In particular, this work investigates how variations in local properties within the substrate (i.e. differences between properties in constituent phases) can affect heat transport into the substrate. Furthermore, this can affect the microstructural evolution observed within the substrate, which may affect the final joint properties. The effect of the initial substrate microstructure on microstructural evolution within themore » heat-affected zone is evaluated experimentally in two Sn-Zn alloys and numerical techniques are utilized to inform the analysis.« less

Delignified and Densified Cellulose Bulk Materials with Excellent Tensile Properties for Sustainable Engineering.

PubMed

Frey, Marion; Widner, Daniel; Segmehl, Jana S; Casdorff, Kirstin; Keplinger, Tobias; Burgert, Ingo

2018-02-07

Today's materials research aims at excellent mechanical performance in combination with advanced functionality. In this regard, great progress has been made in tailoring the materials by assembly processes in bottom-up approaches. In the field of wood-derived materials, nanocellulose research has gained increasing attention, and materials with advanced properties were developed. However, there are still unresolved issues concerning upscaling for large-scale applications. Alternatively, the sophisticated hierarchical scaffold of wood can be utilized in a top-down approach to upscale functionalization, and one can profit at the same time from its renewable nature, CO 2 storing capacity, light weight, and good mechanical performance. Nevertheless, for bulk wood materials, a wider multipurpose industrial use is so far impeded by concerns regarding durability, natural heterogeneity as well as limitations in terms of functionalization, processing, and shaping. Here, we present a novel cellulose bulk material concept based on delignification and densification of wood resulting in a high-performance material. A delignification process using hydrogen peroxide and acetic acid was optimized to delignify the entire bulk wooden blocks and to retain the highly beneficial structural directionality of wood. In a subsequent step, these cellulosic blocks were densified in a process combining compression and lateral shear to gain a very compact cellulosic material with entangled fibers while retaining unidirectional fiber orientation. The cellulose bulk materials obtained by different densification protocols were structurally, chemically, and mechanically characterized revealing superior tensile properties compared to native wood. Furthermore, after delignification, the cellulose bulk material can be easily formed into different shapes, and the delignification facilitates functionalization of the bioscaffold.

Investigation on mechanical properties of basalt composite fabrics (experiment study)

NASA Astrophysics Data System (ADS)

Talebi Mazraehshahi, H.; Zamani, H.

2010-06-01

To fully appreciate the role and application of composite materials to structures, correct understanding of mechanical behaviors required for selection of optimum material. Fabric reinforced composites are composed of a matrix that is reinforced with pliable fabric, glass fabric is most popular reinforcement for different application specially in aircraft structure, although other fabric material are also used. At this study new fabric material called basalt with epoxy resin introduced and mechanical behaviors of this material investigated from view point of testing. For this study two type of fabric with different thickness used. Comparison between this composite reinforcement with popular reinforcement as carbon, glass, kevlar performed. To determine mechanical properties of epoxy based basalt fabric following test procedure performed : 1). Tensile testing according to ASTM D3039 in 0° and 90° direction to find ultimate strength in tension and shear, modulus of elasticity, elangation and ultimate strain. 2). Compression testing according to EN 2850 ultimate compression strength and maximum deformation under compression loading. 3). Shear testing according to ASTM D3518-94 to find in plane shear response of polymer matrix composites materials. 4). Predict flexural properties of sandwich construction which manufactured from basalt facing with PVC foam core according to ASTM C393-94. Material strength properties must be based on enough tests of material to meet the test procedure specifications [1]. For this reason six specimens were manufactured for testing and the tests were performed on them using an INSTRON machine model 5582. In the study, the effect of percent of resin in basalt reinforced composite was investigated. Also the weights of the ballast based composites with different percent of resin were measured with conventional composites. As the weight is an important parameter in aerospace industry when the designer wants to replace one material with another, the effect of weight must be considered. Weight measurement showed that the replacement of glass fabric reinforcement with basalt fabric has little effect on weight. Investigation also shows that mechanical behavior of basalt fabric is higher than glass fabric. This is due to the excellent mechanical properties of the ballast fabric such as Young modulus and strength in compare with the glass fabric. Figure1 shows the samples which used for tensile testing in warp direction.

Influence of the recycled material percentage on the rheological behaviour of HDPE for injection moulding process.

PubMed

Javierre, C; Clavería, I; Ponz, L; Aísa, J; Fernández, A

2007-01-01

The amount of polymer material wasted during thermoplastic injection moulding is very high. It comes from both the feed system of the part, and parts necessary to set up the mould, as well as the scrap generated along the process due to quality problems. The residues are managed through polymer recycling that allows reuse of the materials in the manufacturing injection process. Recycling mills convert the parts into small pieces that are used as feed material for injection, by mixing the recycled feedstock in different percentages with raw material. This mixture of both raw and recycled material modifies material properties according to the percentage of recycled material introduced. Some of the properties affected by this modification are those related to rheologic behaviour, which strongly conditions the future injection moulding process. This paper analyzes the rheologic behaviour of material with different percentages of recycled material by means of a capillary rheometer, and evaluates the influence of the corresponding viscosity curves obtained on the injection moulding process, where small variations of parameters related to rheological behaviour, such as pressure or clamping force, can be critical to the viability and cost of the parts manufactured by injection moulding.

Effect of artificial toothbrushing and water storage on the surface roughness and micromechanical properties of tooth-colored CAD-CAM materials.

PubMed

Flury, Simon; Diebold, Elisabeth; Peutzfeldt, Anne; Lussi, Adrian

2017-06-01

Because of the different composition of resin-ceramic computer-aided design and computer-aided manufacturing (CAD-CAM) materials, their polishability and their micromechanical properties vary. Moreover, depending on the composition of the materials, their surface roughness and micromechanical properties are likely to change with time. The purpose of this in vitro study was to investigate the effect of artificial toothbrushing and water storage on the surface roughness (Ra and Rz) and the micromechanical properties, surface hardness (Vickers [VHN]) and indentation modulus (E IT ), of 5 different tooth-colored CAD-CAM materials when polished with 2 different polishing systems. Specimens (n=40 per material) were cut from a composite resin (Paradigm MZ100; 3M ESPE), a feldspathic ceramic (Vitablocs Mark II; Vita Zahnfabrik), a resin nanoceramic (Lava Ultimate; 3M ESPE), a hybrid dental ceramic (Vita Enamic; Vita Zahnfabrik), and a nanocomposite resin (Ambarino High-Class; Creamed). All specimens were roughened in a standardized manner and polished either with Sof-Lex XT discs or the Vita Polishing Set Clinical. Surface roughness, VHN, and E IT were measured after polishing and after storage for 6 months (tap water, 37°C) with periodic, artificial toothbrushing. The surface roughness, VHN, and E IT results were analyzed with a nonparametric ANOVA followed by Kruskal-Wallis and exact Wilcoxon rank sum tests (α=.05). Irrespective of polishing system and of artificial toothbrushing and storage, Lava Ultimate generally showed the lowest surface roughness and Vitablocs Mark II the highest. As regards micromechanical properties, the following ranking of the CAD-CAM materials was found (from highest VHN/E IT to lowest VHN/E IT ): Vitablocs Mark II > Vita Enamic > Paradigm MZ100 > Lava Ultimate > Ambarino High-Class. Irrespective of material and of artificial toothbrushing and storage, polishing with Sof-Lex XT discs resulted in lower surface roughness than the Vita Polishing Set Clinical (P≤.016). However, the polishing system generally had no influence on the micromechanical properties (P>.05). The effect of artificial toothbrushing and storage on surface roughness depended on the material and the polishing system: Ambarino High-Class was most sensitive to storage, Lava Ultimate and Vita Enamic were least sensitive. Artificial toothbrushing and storage generally resulted in a decrease in VHN and E IT for Paradigm MZ100, Lava Ultimate, and Ambarino High-Class but not for Vita Enamic and Vitablocs Mark II. Tooth-colored CAD-CAM materials with lower VHN and E IT generally showed better polishability. However, these materials were more prone to degradation by artificial toothbrushing and water storage than materials with higher VHN and E IT . Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Selected engineering properties and applications of EPS geofoam

NASA Astrophysics Data System (ADS)

Elragi, Ahmed Fouad

Expanded polystyrene (EPS) geofoam is a lightweight material that has been used in engineering applications since at least the 1950s. Its density is about a hundredth of that of soil. It has good thermal insulation properties with stiffness and compression strength comparable to medium clay. It is utilized in reducing settlement below embankments, sound and vibration damping, reducing lateral pressure on substructures, reducing stresses on rigid buried conduits and related applications. This study starts with an overview on EPS geofoam. EPS manufacturing processes are described followed by a review of engineering properties found in previous research work done so far. Standards and design manuals applicable to EPS are presented. Selected EPS geofoam-engineering applications are discussed with examples. State-of-the-art of experimental work is done on different sizes of EPS specimens under different loading rates for better understanding of the behavior of the material. The effects of creep, sample size, strain rate and cyclic loading on the stress strain response are studied. Equations for the initial modulus and the strength of the material under compression for different strain rates are presented. The initial modulus and Poisson's ratio are discussed in detail. Sample size effect on creep behavior is examined. Three EPS projects are shown in this study. The creep behavior of the largest EPS geofoam embankment fill is shown. Results from laboratory tests, mathematical modeling and field records are compared to each other. Field records of a geofoam-stabilized slope are compared to finite difference analysis results. Lateral stress reduction on an EPS backfill retaining structure is analyzed. The study ends with a discussion on two promising properties of EPS geofoam. These are the damping ability and the compressibility of this material. Finite element analysis, finite difference analysis and lab results are included in this discussion. The discussion with the rest of the study points towards the main conclusion that EPS geofoam is the future material of promise in various civil engineering applications.

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.

Sol-gel hybrid materials for aerospace applications: Chemical characterization and comparative investigation of the magnetic properties

NASA Astrophysics Data System (ADS)

Catauro, Michelina; Mozzati, Maria Cristina; Bollino, Flavia

2015-12-01

In the material science field, weightless conditions can be successfully used to understand the relationship between manufacturing process, structure and properties of the obtained materials. Aerogels with controlled microstructure could be obtained by sol-gel methods in microgravity environment, simulated using magnetic levitation if they are diamagnetic. In the present work, a sol-gel route was used to synthesize class I, organic-inorganic nanocomposite materials. Two different formulations were prepared: the former consisted in a SiO2 matrix in which different percentages of polyethylene glycol (PEG) were incorporated, the latter was a ZrO2 matrix entrapping different amounts of poly (ε-caprolactone) (PCL). Fourier Transform Infrared Spectroscopy (FT-IR) detected that the organic and the inorganic components in both the formulation interact by means of hydrogen bonds. X-ray diffraction (XRD) analysis highlighted the amorphous nature of the synthesized materials and Scanning Electron Microscope (SEM) showed that they have homogeneous morphology and are nanocomposites. Superconducting Quantum Interference Device (SQUID) magnetometry confirmed the expected diamagnetic character of those hybrid systems. The obtained results were compared to those achieved in previous studies regarding the influence of the polymer amount on the magnetic properties of SiO2/PCL and ZiO2/PEG hybrids, in order to understand how the diamagnetic susceptibility is influenced by variation of both the inorganic matrix and organic component.

Measurement of mechanical and thermophysical properties of dimensionally stable materials for space applications

NASA Technical Reports Server (NTRS)

Rawal, Suraj P.; Misra, Mohan S.

1992-01-01

Mechanical, thermal, and physical property test data was generated for as-fabricated advanced composite materials at room temperature (RT), -150 and 250 F. The results are documented of mechanical and thermophysical property tests of IM7/PEEK and discontinuous SiC/Al (particulate (p) and whisker (w) reinforced) composites which were tested at three different temperatures to determine the effect of temperature on material properties. The specific material systems tested were IM7/PEEK (0)8, (0, + or - 45, 90)s, (+ or - 30, 04)s, 25 vol. pct. (v/o) SiCp/Al, and 25 v/o SiCw/Al. RT material property results of IM7/PEEK were in good agreement with the predicted values, providing a measure of consolidation integrity attained during fabrication. Results of mechanical property tests indicated that modulus values at each test temperature were identical, whereas the strength (e.g., tensile, compressive, flexural, and shear) values were the same at -150 F, and RT, and gradually decreased as the test temperature was increased to 250 F. Similar trends in the strength values was also observed in discontinuous SiC/Al composites. These results indicate that the effect of temperature was more pronounced on the strength values than modulus values.

Verification of cardiac mechanics software: benchmark problems and solutions for testing active and passive material behaviour.

PubMed

Land, Sander; Gurev, Viatcheslav; Arens, Sander; Augustin, Christoph M; Baron, Lukas; Blake, Robert; Bradley, Chris; Castro, Sebastian; Crozier, Andrew; Favino, Marco; Fastl, Thomas E; Fritz, Thomas; Gao, Hao; Gizzi, Alessio; Griffith, Boyce E; Hurtado, Daniel E; Krause, Rolf; Luo, Xiaoyu; Nash, Martyn P; Pezzuto, Simone; Plank, Gernot; Rossi, Simone; Ruprecht, Daniel; Seemann, Gunnar; Smith, Nicolas P; Sundnes, Joakim; Rice, J Jeremy; Trayanova, Natalia; Wang, Dafang; Jenny Wang, Zhinuo; Niederer, Steven A

2015-12-08

Models of cardiac mechanics are increasingly used to investigate cardiac physiology. These models are characterized by a high level of complexity, including the particular anisotropic material properties of biological tissue and the actively contracting material. A large number of independent simulation codes have been developed, but a consistent way of verifying the accuracy and replicability of simulations is lacking. To aid in the verification of current and future cardiac mechanics solvers, this study provides three benchmark problems for cardiac mechanics. These benchmark problems test the ability to accurately simulate pressure-type forces that depend on the deformed objects geometry, anisotropic and spatially varying material properties similar to those seen in the left ventricle and active contractile forces. The benchmark was solved by 11 different groups to generate consensus solutions, with typical differences in higher-resolution solutions at approximately 0.5%, and consistent results between linear, quadratic and cubic finite elements as well as different approaches to simulating incompressible materials. Online tools and solutions are made available to allow these tests to be effectively used in verification of future cardiac mechanics software.

Predicting physical properties of emerging compounds with limited physical and chemical data: QSAR model uncertainty and applicability to military munitions.

PubMed

Bennett, Erin R; Clausen, Jay; Linkov, Eugene; Linkov, Igor

2009-11-01

Reliable, up-front information on physical and biological properties of emerging materials is essential before making a decision and investment to formulate, synthesize, scale-up, test, and manufacture a new material for use in both military and civilian applications. Multiple quantitative structure-activity relationships (QSARs) software tools are available for predicting a material's physical/chemical properties and environmental effects. Even though information on emerging materials is often limited, QSAR software output is treated without sufficient uncertainty analysis. We hypothesize that uncertainty and variability in material properties and uncertainty in model prediction can be too large to provide meaningful results. To test this hypothesis, we predicted octanol water partitioning coefficients (logP) for multiple, similar compounds with limited physical-chemical properties using six different commercial logP calculators (KOWWIN, MarvinSketch, ACD/Labs, ALogP, CLogP, SPARC). Analysis was done for materials with largely uncertain properties that were similar, based on molecular formula, to military compounds (RDX, BTTN, TNT) and pharmaceuticals (Carbamazepine, Gemfibrizol). We have also compared QSAR modeling results for a well-studied pesticide and pesticide breakdown product (Atrazine, DDE). Our analysis shows variability due to structural variations of the emerging chemicals may be several orders of magnitude. The model uncertainty across six software packages was very high (10 orders of magnitude) for emerging materials while it was low for traditional chemicals (e.g. Atrazine). Thus the use of QSAR models for emerging materials screening requires extensive model validation and coupling QSAR output with available empirical data and other relevant information.

Different Material States of Pub1 Condensates Define Distinct Modes of Stress Adaptation and Recovery.

PubMed

Kroschwald, Sonja; Munder, Matthias C; Maharana, Shovamayee; Franzmann, Titus M; Richter, Doris; Ruer, Martine; Hyman, Anthony A; Alberti, Simon

2018-06-12

How cells adapt to varying environmental conditions is largely unknown. Here, we show that, in budding yeast, the RNA-binding and stress granule protein Pub1 has an intrinsic property to form condensates upon starvation or heat stress and that condensate formation is associated with cell-cycle arrest. Release from arrest coincides with condensate dissolution, which takes minutes (starvation) or hours (heat shock). In vitro reconstitution reveals that the different dissolution rates of starvation- and heat-induced condensates are due to their different material properties: starvation-induced Pub1 condensates form by liquid-liquid demixing and subsequently convert into reversible gel-like particles; heat-induced condensates are more solid-like and require chaperones for disaggregation. Our data suggest that different physiological stresses, as well as stress durations and intensities, induce condensates with distinct physical properties and thereby define different modes of stress adaptation and rates of recovery. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Material Modeling of Stony Meteorites for Mechanical Properties

NASA Astrophysics Data System (ADS)

Agrawal, P.

2016-12-01

To assess the threat posed by an asteroid entering Earth's atmosphere, one must predict if, when, and how it fragments during entry. A comprehensive understanding of the asteroid material properties is needed to achieve this objective. At present, the meteorite material found on earth are the only objects (other than synthetic meteorites) from an entering asteroid that can be used as representative material and be tested inside a laboratory setting. Due to limited number of meteorites available for testing it is difficult to develop a material model that can be purely based on statistics from the test data. Therefore, we are developing computational models to determine the effective material properties of stony meteorites and in turn deduce the properties of asteroids. The internal structure of meteorites are very complex. They consists of several minerals that include the silica based materials such as Olivine, Pyroxene, Feldspar that are found in terrestrial rocks, as well as Fe-Ni based minerals such as Kamacite, Troilite and Taenite that are unique to meteorites. Each of these minerals have different densities and mechanical properties. In addition, the meteorites have different phases that can be summarized as chondrules, metal and matrix. The meteorites have varying degree of porosity and pre-cracked structure. In order to account for diverse petrology of the meteorites a unique methodology is developed the form of unit cell model. The unit cell is representative volume that accounts for diverse minerals, porosity, and matrix composition inside a meteorite. All the minerals and phases inside these unit cells are randomly distributed. Several hundreds of Monte-Carlo simulations are performed to generate the effective mechanical properties such as Young's Modulus and Poisson's Ratio of the unit cell. Stress-strain curves as well as strength estimates are generated based on the unit cell models. These estimates will used as material models for full scale modeling of atmospheric entry for asteroids. Terrestrial analogs such as Basalt and Gabbro are being used to validate the unit cell methodology. Structural tests are also being performed on some of the meteorites including Tamdakht and Mbole to validate the predictions from unit cell models.

SU-F-E-10: Student-Driven Exploration of Radiographic Material Properties, Phantom Construction, and Clinical Workflows Or: The Extraordinary Life of CANDY MAN

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahon, RN; Riblett, MJ; Hugo, GD

Purpose: To develop a hands-on learning experience that explores the radiological and structural properties of everyday items and applies this knowledge to design a simple phantom for radiotherapy exercises. Methods: Students were asked to compile a list of readily available materials thought to have radiation attenuation properties similar to tissues within the human torso. Participants scanned samples of suggested materials and regions of interest (ROIs) were used to characterize bulk attenuation properties. Properties of each material were assessed via comparison to a Gammex Tissue characterization phantom and used to construct a list of inexpensive near-tissue-equivalent materials. Critical discussions focusing onmore » samples found to differ from student expectations were used to revise and narrow the comprehensive list. From their newly acquired knowledge, students designed and constructed a simple thoracic phantom for use in a simulated clinical workflow. Students were tasked with setting up the phantom and acquiring planning CT images for use in treatment planning and dose delivery. Results: Under engineer and physicist supervision, students were trained to use a CT simulator and acquired images for approximately 60 different foodstuffs, candies, and household items. Through peer discussion, students gained valuable insights and were made to review preconceptions about radiographic material properties. From a subset of imaged materials, a simple phantom was successfully designed and constructed to represent a human thorax. Students received hands-on experience with clinical treatment workflows by learning how to perform CT simulation, create a treatment plan for an embedded tumor, align the phantom for treatment, and deliver a treatment fraction. Conclusion: In this activity, students demonstrated their ability to reason through the radiographic material selection process, construct a simple phantom to specifications, and exercise their knowledge of clinical workflows. Furthermore, the enjoyable and inexpensive nature of this project proved to attract participant interest and drive creative exploration. Mahon and Riblett have nothing to disclose; Hugo has a research agreement with Phillips Medical systems, a license agreement with Varian Medical Systems, research grants from the National Institute of Health. Authors do not have any potential conflicts of interest to disclose.« less

On the relationships between hardness and the elastic and plastic properties of isotropic power-law hardening materials

NASA Astrophysics Data System (ADS)

Lan, Hongzhi; Venkatesh, T. A.

2014-01-01

A comprehensive understanding of the relationship between the hardness and the elastic and plastic properties for a wide range of materials is obtained by analysing the hardness characteristics (that are predicted by experimentally verified indentation analyses) of over 9000 distinct combinations of material properties that represent isotropic, homogeneous, power-law hardening metallic materials. Finite element analysis has been used to develop the indentation algorithms that provide the relationships between the elastic and plastic properties of the indented material and its indentation hardness. Based on computational analysis and virtual testing, the following observations are made. The hardness (H) of a material tends to increase with an increase in the elastic modulus (E), yield strength (σy) and the strain-hardening exponent (n). Several materials with different combinations of elastic and plastic properties can exhibit identical true hardness (for a particular indenter geometry/apex angle). In general, combinations of materials that exhibit relatively low elastic modulus and high yield strength or strain-hardening exponents and those that exhibit relatively high elastic modulus and low yield strength or strain-hardening exponents exhibit similar hardness properties. Depending on the strain-hardening characteristics of the indented material, (i.e. n = 0 or ?), the ratio H/σy ranges, respectively, from 2.2 to 2.6 or 2 to 20 (for indentations with a cone angle of 70.3°). The materials that have lower σy/E and higher n exhibit higher H/σy ratios. The commonly invoked relationship between hardness and the yield strength, i.e. H ≈ 3σy, is not generally valid or applicable for all power-law hardening materials. The indentation hardness of a power law hardening material can be taken as following the relationship H ≈ (2.1-2.8)σr where σr is the representative stress based on Tabor's representative strain for a wide range of materials.

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.

'Own-Label' Versus Branded Commercial Dental Resin Composite Materials: Mechanical And Physical Property Comparisons.

PubMed

Shaw, Kathryn; Martins, Ricardo; Hadis, Mohammed Abdul; Burke, Trevor; Palin, William

2016-09-01

A majority of dental materials are manufactured by companies who have experience in the field. However, a number of "own label" materials have become available, principally marketed by distributors and other companies with little or no experience in the field. These materials are attractive because of their reduced cost, but they may have no research on which clinicians might base their potential performance. It is therefore the purpose of this work to compare the performance of different batches of a number of "own-label" dental materials with a similar number from manufacturers with experience in the field, using a variety of laboratory test regimes which include filler determination, degree of conversion, flexural strength and flexural modulus, in order to evaluate key material properties. The results indicated that own-label dental resin composites produced similar results to materials from established companies in terms of flexural strength characteristics and degree of conversion. However, a greater batch-to-batch variation in several mechanical and physical properties of the own-label materials was noted. Copyright© 2016 Dennis Barber Ltd.

Silica sol as grouting material: a physio-chemical analysis.

PubMed

Sögaard, Christian; Funehag, Johan; Abbas, Zareen

2018-01-01

At present there is a pressing need to find an environmentally friendly grouting material for the construction of tunnels. Silica nanoparticles hold great potential of replacing the organic molecule based grouting materials currently used for this purpose. Chemically, silica nanoparticles are similar to natural silicates which are essential components of rocks and soil. Moreover, suspensions of silica nanoparticles of different sizes and desired reactivity are commercially available. However, the use of silica nanoparticles as grouting material is at an early stage of its technological development. There are some critical parameters such as long term stability and functionality of grouted silica that need to be investigated in detail before silica nanoparticles can be considered as a reliable grouting material. In this review article we present the state of the art regarding the chemical properties of silica nanoparticles commercially available, as well as experience gained from the use of silica as grouting material. We give a detailed description of the mechanisms underlying the gelling of silica by different salt solutions such as NaCl and KCl and how factors such as particle size, pH, and temperature affect the gelling and gel strength development. Our focus in this review is on linking the chemical properties of silica nanoparticles to the mechanical properties to better understand their functionality and stability as grouting material. Along the way we point out areas which need further research.

Nanofiber-bonded cloth materials based on poly-3-hydroxybutyrate with antibacterial properties for medical purposes

NASA Astrophysics Data System (ADS)

Tyubaeva, P. M.; Olkhov, A. A.; Karpova, S. G.; Iordansky, A. L.; Popov, A. A.

2017-12-01

Different transdermal systems based on solid polymer matrices or gels containing functional substances with antiseptic (antibacterial) properties have application to the therapy of many infectious diseases and cancer. Today the most promising type of matrices with antiseptic characteristics are the nano- and microfiber nonwoven materials. Fibers on the biopolymer (poly(3-hydroxybutyrate)) basis were obtained using the electrospinning method. In the present work, the effects of iron (III) complex with tetraphenylporphyrin and its influence on bactericidal and antibacterial properties of the ultrathin PHB fibers were investigated.

3D printing process of oxidized nanocellulose and gelatin scaffold.

PubMed

Xu, Xiaodong; Zhou, Jiping; Jiang, Yani; Zhang, Qi; Shi, Hongcan; Liu, Dongfang

2018-08-01

For tissue engineering applications tissue scaffolds need to have a porous structure to meet the needs of cell proliferation/differentiation, vascularisation and sufficient mechanical strength for the specific tissue. Here we report the results of a study of the 3D printing process for composite materials based on oxidized nanocellulose and gelatin, that was optimised through measuring rheological properties of different batches of materials after different crosslinking times, simulation of the pneumatic extrusion process and 3D scaffolds fabrication with Solidworks Flow Simulation, observation of its porous structure by SEM, measurement of pressure-pull performance, and experiments aimed at finding out the vitro cytotoxicity and cell morphology. The materials printed are highly porous scaffolds with good mechanical properties.

A practical guide to using boron doped diamond in electrochemical research.

PubMed

Macpherson, Julie V

2015-02-07

Conducting, boron doped diamond (BDD), in addition to its superior material properties, offers several notable attributes to the electrochemist making it an intriguing material for electrochemical research. These include the widest solvent window of all electrode materials; low background and capacitive currents; reduced fouling compared to other electrodes and; the ability to withstand extreme potentials, corrosive and high temperature/pressure environments. However, BDD is not your typical electrode material, it is a semi-conductor doped degenerately with boron to present semi-metallic characteristics. Input from materials scientists, chemists and physicists has been required to aid understanding of how to work with this material from an electrochemical viewpoint and improve electrode quality. Importantly, depending on how the BDD has been grown and then subsequently treated, prior to electrochemical measurement, the resulting material properties can vary quite significantly from one electrode to the next. This likely explains the variability seen by different researchers working on the same experimental systems. The aim of this "protocols" article is not to provide a state-of-the-art review of diamond electrochemistry, suitable references are provided to the interested reader, but instead serves as a reference point for any researcher wishing to commence work with diamond electrodes and interpret electrochemical data. It provides information on how best to characterise the material properties of the electrode before use and outlines the interplay between boron dopant density, non-diamond-carbon content, grain morphology, surface chemistry and redox couple identity. All should ideally be considered when interpretating electrochemical data arising from the diamond electrode. This will aid the reader in making meaningful comparisons between data obtained by different researchers using different diamond electrodes. The guide also aims to help educate the researcher in choosing which form of BDD is best suited to their research application.

Evaluation of phenyl-propanedione on yellowing and chemical-mechanical properties of experimental dental resin-based materials.

PubMed

Oliveira, Dayane Carvalho Ramos Salles de; Souza-Junior, Eduardo José; Dobson, Adam; Correr, Ana Rosa Costa; Brandt, William Cunha; Sinhoreti, Mário Alexandre Coelho

2016-01-01

To evaluate the influence of phenyl-propanedione on yellowing and chemical-mechanical properties of experimental resin-based materials photoactivated using different light curing units (LCUs). Experimental resin-based materials with the same organic matrix (60:40 wt% BisGMA:TEGDMA) were mechanically blended using a centrifugal mixing device. To this blend, different photoinitiator systems were added in equimolar concentrations with aliphatic amine doubled by wt%: 0.4 wt% CQ; 0.38 wt% PPD; or 0.2 wt% CQ and 0.19 wt% PPD. The degree of conversion (DC), flexural strength (FS), Young's modulus (YM), Knoop hardness (KNH), crosslinking density (CLD), and yellowing (Y) were evaluated (n=10). All samples were light cured with the following LCUs: a halogen lamp (XL 2500), a monowave LED (Radii), or a polywave LED (Valo) with 16 J/cm2. The results were analysed by two-way ANOVA and Tukey's test (α=0.05). No statistical differences were found between the different photoinitiator systems to KNH, CLS, FS, and YM properties (p≥0.05). PPD/CQ association showed the higher DC values compared with CQ and PPD isolated systems when photoactivated by a polywave LED (p≤0.05). Y values were highest for the CQ compared with the PPD systems (p≤0.05). PPD isolated system promoted similar chemical and mechanical properties and less yellowing compared with the CQ isolated system, regardless of the LCU used.

Comparison Of Models Of Metal-Matrix Composites

NASA Technical Reports Server (NTRS)

Bigelow, C. A.; Johnson, W. S.; Naik, R. A.

1994-01-01

Report presents comparative review of four mathematical models of micromechanical behaviors of fiber/metal-matrix composite materials. Models differ in various details, all based on properties of fiber and matrix constituent materials, all involve square arrays of fibers continuous and parallel and all assume complete bonding between constituents. Computer programs implementing models used to predict properties and stress-vs.-strain behaviors of unidirectional- and cross-ply laminated composites made of boron fibers in aluminum matrices and silicon carbide fibers in titanium matrices. Stresses in fiber and matrix constituent materials also predicted.

A Multiscale Virtual Fabrication and Lattice Modeling Approach for the Fatigue Performance Prediction of Asphalt Concrete

NASA Astrophysics Data System (ADS)

Dehghan Banadaki, Arash

Predicting the ultimate performance of asphalt concrete under realistic loading conditions is the main key to developing better-performing materials, designing long-lasting pavements, and performing reliable lifecycle analysis for pavements. The fatigue performance of asphalt concrete depends on the mechanical properties of the constituent materials, namely asphalt binder and aggregate. This dependent link between performance and mechanical properties is extremely complex, and experimental techniques often are used to try to characterize the performance of hot mix asphalt. However, given the seemingly uncountable number of mixture designs and loading conditions, it is simply not economical to try to understand and characterize the material behavior solely by experimentation. It is well known that analytical and computational modeling methods can be combined with experimental techniques to reduce the costs associated with understanding and characterizing the mechanical behavior of the constituent materials. This study aims to develop a multiscale micromechanical lattice-based model to predict cracking in asphalt concrete using component material properties. The proposed algorithm, while capturing different phenomena for different scales, also minimizes the need for laboratory experiments. The developed methodology builds on a previously developed lattice model and the viscoelastic continuum damage model to link the component material properties to the mixture fatigue performance. The resulting lattice model is applied to predict the dynamic modulus mastercurves for different scales. A framework for capturing the so-called structuralization effects is introduced that significantly improves the accuracy of the modulus prediction. Furthermore, air voids are added to the model to help capture this important micromechanical feature that affects the fatigue performance of asphalt concrete as well as the modulus value. The effects of rate dependency are captured by implementing the viscoelastic fracture criterion. In the end, an efficient cyclic loading framework is developed to evaluate the damage accumulation in the material that is caused by long-sustained cyclic loads.

Effects of Ceramic Density and Sintering Temperature on the Mechanical Properties of a Novel Polymer-Infiltrated Ceramic-Network Zirconia Dental Restorative (Filling) Material.

PubMed

Li, Weiyan; Sun, Jian

2018-05-10

BACKGROUND Polymer-infiltrated ceramic-network (PICN) dental material is a new and practical development in orthodontics. Sintering is the process of forming a stable solid mass from a powder by heating without melting. The aim of this study was to evaluate the effects of sintering temperature on the mechanical properties of a PICN zirconia dental material. MATERIAL AND METHODS A dense zirconia ceramic and four PICN zirconia dental materials, with varying porosities, were sintered at three different temperatures; 12 PICN zirconia dental materials based on these porous ceramics were prepared, as well as a pure polymer. After the specimen preparation, flexural strength and elastic modulus values were measured using the three-point bending test, and fracture toughness were determined by the single-edge notched beam (SENB) method. The Vickers hardness test method was used with an indentation strength (IS) test. Scanning electron microscopy (SEM) was used to examine the microstructure of the ceramic surface and the fracture surface. RESULTS Mechanical properties of the PICN dental materials, including flexural strength, elastic modulus, fracture toughness, and hardness, were more similar to the properties of natural teeth when compared with traditional dental ceramic materials, and were affected by the density and sintering temperature. SEM showed that the porous ceramic network became cohesive and that the length of cracks in the PICN dental material was reduced. CONCLUSIONS PICN zirconia dental materials were characterized by similar mechanical properties to natural dental tissues, but further studies are required continue to improve the similarities with natural human enamel and dentin.

Effects of Ceramic Density and Sintering Temperature on the Mechanical Properties of a Novel Polymer-Infiltrated Ceramic-Network Zirconia Dental Restorative (Filling) Material

PubMed Central

Li, Weiyan

2018-01-01

Background Polymer-infiltrated ceramic-network (PICN) dental material is a new and practical development in orthodontics. Sintering is the process of forming a stable solid mass from a powder by heating without melting. The aim of this study was to evaluate the effects of sintering temperature on the mechanical properties of a PICN zirconia dental material. Material/Methods A dense zirconia ceramic and four PICN zirconia dental materials, with varying porosities, were sintered at three different temperatures; 12 PICN zirconia dental materials based on these porous ceramics were prepared, as well as a pure polymer. After the specimen preparation, flexural strength and elastic modulus values were measured using the three-point bending test, and fracture toughness were determined by the single-edge notched beam (SENB) method. The Vickers hardness test method was used with an indentation strength (IS) test. Scanning electron microscopy (SEM) was used to examine the microstructure of the ceramic surface and the fracture surface. Results Mechanical properties of the PICN dental materials, including flexural strength, elastic modulus, fracture toughness, and hardness, were more similar to the properties of natural teeth when compared with traditional dental ceramic materials, and were affected by the density and sintering temperature. SEM showed that the porous ceramic network became cohesive and that the length of cracks in the PICN dental material was reduced. Conclusions PICN zirconia dental materials were characterized by similar mechanical properties to natural dental tissues, but further studies are required continue to improve the similarities with natural human enamel and dentin. PMID:29746449

Application of the matrix exponential kernel

NASA Technical Reports Server (NTRS)

Rohach, A. F.

1972-01-01

A point matrix kernel for radiation transport, developed by the transmission matrix method, has been used to develop buildup factors and energy spectra through slab layers of different materials for a point isotropic source. Combinations of lead-water slabs were chosen for examples because of the extreme differences in shielding properties of these two materials.

Temperature dependence of thermal boundary resistances between multiwalled carbon nanotubes and some typical counterpart materials.

PubMed

Zhang, Guang; Liu, Changhong; Fan, Shoushan

2012-04-24

We directly measured the temperature dependence of thermal boundary resistances (TBRs) between multiwalled carbon nanotubes (MWCNTs) and different materials at elevated temperatures. Using the steady-state heat flow and the noncontacted measurement method, we could conveniently obtain the TBR-temperature relations. Our results indicate that the TBR-temperature relations vary distinctively with different contact materials when heating temperatures change from about 300 to 450 K; that is, the CNT-metal TBRs increase with increasing temperatures, whereas the CNT-insulator TBRs decrease. As a comparison, the TBRs between superaligned MWCNTs were measured and we found that the CNT-CNT TBRs remain basically unchanged as temperatures increase. We also found that the magnitude of TBRs between MWCNTs and different materials could differ from each other significantly. These results suggest that the choice of the right electrode may have an obvious influence on the thermal properties and other properties of the CNT-based devices. From another perspective, in view of some existing theoretical models about TBRs, our results support the validity of the molecular dynamics (MD) simulations in the calculation of CNT-solid TBRs at elevated temperatures.

Impact response of composite materials

NASA Technical Reports Server (NTRS)

Tiwari, S. N.; Srinivasan, K.

1991-01-01

Composite materials composed of carbon fibers and resin matrices offer great promise in reducing the weight of aerospace structures. However they remain extremely vulnerable to out of plane impact loads, which lead to severe losses in strength and stiffness. The results of an experimental program, undertaken to investigate the low velocity impact damage tolerance of composite materials is presented. The objectives were to identify key neat resin/composite properties that lead to enhancement of composite impact damage tolerance and to find a small scale test that predicts compression after impact properties of panels. Five materials were selected for evaluation. These systems represented different classes of material behavior such as brittle epoxy, modified epoxies, and amorphous and semicrystalling thermoplastics. The influence of fiber properties on the impact performance was also studied in one material, i.e., in polyether ether ketone (PEEK). Several 24 and 48 ply quasi-isotropic and 24 ply orthotropic laminates were examined using an instrumented drop weight impactor. Correlations with post impact compression behavior were made.

Strong room-temperature ferromagnetism in VSe2 monolayers on van der Waals substrates

NASA Astrophysics Data System (ADS)

Bonilla, Manuel; Kolekar, Sadhu; Ma, Yujing; Diaz, Horacio Coy; Kalappattil, Vijaysankar; Das, Raja; Eggers, Tatiana; Gutierrez, Humberto R.; Phan, Manh-Huong; Batzill, Matthias

2018-04-01

Reduced dimensionality and interlayer coupling in van der Waals materials gives rise to fundamentally different electronic1, optical2 and many-body quantum3-5 properties in monolayers compared with the bulk. This layer-dependence permits the discovery of novel material properties in the monolayer regime. Ferromagnetic order in two-dimensional materials is a coveted property that would allow fundamental studies of spin behaviour in low dimensions and enable new spintronics applications6-8. Recent studies have shown that for the bulk-ferromagnetic layered materials CrI3 (ref. 9) and Cr2Ge2Te6 (ref. 10), ferromagnetic order is maintained down to the ultrathin limit at low temperatures. Contrary to these observations, we report the emergence of strong ferromagnetic ordering for monolayer VSe2, a material that is paramagnetic in the bulk11,12. Importantly, the ferromagnetic ordering with a large magnetic moment persists to above room temperature, making VSe2 an attractive material for van der Waals spintronics applications.

Rheological study of clay-kaolin aqueous suspensions

NASA Technical Reports Server (NTRS)

Lapasin, R.; Lucchini, F.

1984-01-01

Rheological characteristics of clay-kaolin aqueous suspensions were studied by a rotational viscometer to correlate their behavior with the properties of ceramic slips for casting containing quartz, feldspars, and other nonplastic materials. In particular, the effects of the different amounts of dry materials and deflocculant (mixture 1:1 of Na2CO3 and Na2SiO3) and of temperatures on the shear-time-dependent properties of suspensions were examined.

Three-Dimensional, Inelastic Response of Single-Edge Notch Bend Specimens Subjected to Impact Loading

DTIC Science & Technology

1993-08-01

measure the inherent fracture toughness of a material. A thor- ough understanding of the test specimen behavior is a prerequisite to the application of...measured material properties in structural applications . Three- dimensional dynamic analyses are performed for three different specimen configurations...derstanding of the test specimen behavior is a prerequisite to the application of measured ma- terial properties in structural applications . Three

Study of the thermal properties of selected PCMs for latent heat storage in buildings

NASA Astrophysics Data System (ADS)

Valentova, Katerina; Pechackova, Katerina; Prikryl, Radek; Ostry, Milan; Zmeskal, Oldrich

2017-07-01

The paper is focused on measurements of thermal properties of selected phase change materials (PCMs) which can be used for latent heat storage in building structures. The thermal properties were measured by the transient step-wise method and analyzed by the thermal spectroscopy. The results of three different materials (RT18HC, RT28HC, and RT35HC) and their thermal properties in solid, liquid, and phase change region were determined. They were correlated with the differential scanning calorimetry (DSC) measurement. The results will be used to determine the optimum ratio of components for the construction of drywall and plasters containing listed ingredients, respectively.

The manufacture and use of sludge test materials for R and D purposes in the treatment and processing of magnox based sludge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blackburn, D.R.; Thompson, E.J.

2013-07-01

Among the Intermediate Level Waste materials in store and awaiting treatment and processing in the UK are quantities of magnesium hydroxide sludge. This sludge is a product of radioactive Magnox Swarf which arose from the de-canning of used magnox fuel element rods. As the Swarf was stored underwater, a corrosion reaction occurred over the course of time between the magnox and the water resulting in a magnesium hydroxide based sludge. The differing conditions and materials present in the various storage areas means that the sludge can range in consistency from that of a slurry through to a thick clay. Sludgemore » test materials are required to underpin and validate the research and development equipment and processes that are to be used to treat the waste material. Necessary restrictions imposed on the sampling and testing of the radioactive waste means that the available data on the properties and behaviour of the sludge is limited. The raw materials used to create the sludge test materials are based upon magnesium hydroxide so that as far as possible the chemical behaviour will be similar to that of the waste material. The most representative sludge test material is manufactured by the corrosion of non-radioactive magnox or magnesium. However, time constraints make it impractical to supply this material in sufficient quantities for full scale validation trials. An alternative is to use sludge manufactured from commercially available magnesium hydroxide. The particle shape of commercially available materials differs from corrosion product magnesium hydroxide which means that properties such as the rheological behaviour cannot be replicated. Nevertheless, valuable trial data can be obtained, giving a greater degree of confidence in the waste treatment process than would be possible if only the more representative but less available corrosion product materials were to be used. Key test material parameters used in the trials have been identified as the particle size distribution and the sludge thickness (measured as yield shear strength). Other properties including cohesion, adhesion and rheological behaviour are also considered. The use of different mixers for sludge manufacture has the potential to affect the behavioural properties and a brief description of each of these mixers is included. The scale of mixing has been found to make a significant difference to the ageing. A chemical impurity in the commercially available materials has been successfully exploited, so that sludge mixed at comparatively low yield shear strengths can thicken into the consistency of clay. This aids manufacture and allows large quantities of thick material to be produced relatively easily. (authors)« less

Real time recognition of explosophorous group and explosive material using laser induced photoacoustic spectroscopy associated with novel algorithm for time and frequency domain analysis.

PubMed

El-Sharkawy, Yasser H; Elbasuney, Sherif

2018-06-07

Energy-rich bonds such as nitrates (NO 3 - ) and percholorates (ClO 4 - ) have an explosive nature; they are frequently encountered in high energy materials. These bonds encompass two highly electronegative atoms competing for electrons. Common explosive materials including urea nitrate, ammonium nitrate, and ammonium percholorates were subjected to photoacoustic spectroscopy. The captured signal was processed using novel digital algorithm designed for time and frequency domain analysis. Frequency domain analysis offered not only characteristic frequencies for NO 3 - and ClO 4 - groups; but also characteristic fingerprint spectra (based on thermal, acoustical, and optical properties) for different materials. The main outcome of this study is that phase-shift domain analysis offered an outstanding signature for each explosive material, with novel discrimination between explosive and similar non-explosive material. Photoacoustic spectroscopy offered different characteristic signatures that can be employed for real time detection with stand-off capabilities. There is no two materials could have the same optical, thermal, and acoustical properties. Copyright © 2018 Elsevier B.V. All rights reserved.

Perspectives on Li and transition metal fluoride phosphates as cathode materials for a new generation of Li-ion batteries.

PubMed

Antipov, Evgeny V; Khasanova, Nellie R; Fedotov, Stanislav S

2015-01-01

To satisfy the needs of rapidly growing applications, Li-ion batteries require further significant improvements of their key properties: specific energy and power, cyclability, safety and costs. The first generation of cathode materials for Li-ion batteries based on mixed oxides with either spinel or rock-salt derivatives has already been widely commercialized, but the potential to improve the performance of these materials further is almost exhausted. Li and transition metal inorganic compounds containing different polyanions are now considered as the most promising cathode materials for the next generation of Li-ion batteries. Further advances in cathode materials are considered to lie in combining different anions [such as (XO4) (n-) and F(-)] in the anion sublattice, which is expected to enhance the specific energy and power of these materials. This review focuses on recent advances related to the new class of cathode materials for Li-ion batteries containing phosphate and fluoride anions. Special attention is given to their crystal structures and the relationships between structure and properties, which are important for their possible practical applications.

Theoretical calculating the thermodynamic properties of solid sorbents for CO{sub 2} capture applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duan, Yuhua

2012-11-02

Since current technologies for capturing CO{sub 2} to fight global climate change are still too energy intensive, there is a critical need for development of new materials that can capture CO{sub 2} reversibly with acceptable energy costs. Accordingly, solid sorbents have been proposed to be used for CO{sub 2} capture applications through a reversible chemical transformation. By combining thermodynamic database mining with first principles density functional theory and phonon lattice dynamics calculations, a theoretical screening methodology to identify the most promising CO{sub 2} sorbent candidates from the vast array of possible solid materials has been proposed and validated. The calculatedmore » thermodynamic properties of different classes of solid materials versus temperature and pressure changes were further used to evaluate the equilibrium properties for the CO{sub 2} adsorption/desorption cycles. According to the requirements imposed by the pre- and post- combustion technologies and based on our calculated thermodynamic properties for the CO{sub 2} capture reactions by the solids of interest, we were able to screen only those solid materials for which lower capture energy costs are expected at the desired pressure and temperature conditions. Only those selected CO{sub 2} sorbent candidates were further considered for experimental validations. The ab initio thermodynamic technique has the advantage of identifying thermodynamic properties of CO{sub 2} capture reactions without any experimental input beyond crystallographic structural information of the solid phases involved. Such methodology not only can be used to search for good candidates from existing database of solid materials, but also can provide some guidelines for synthesis new materials. In this presentation, we first introduce our screening methodology and the results on a testing set of solids with known thermodynamic properties to validate our methodology. Then, by applying our computational method to several different kinds of solid systems, we demonstrate that our methodology can predict the useful information to help developing CO{sub 2} capture Technologies.« less

Thermographic Assessment of the HAZ Properties and Structure of Thermomechanically Treated Steel

NASA Astrophysics Data System (ADS)

Górka, Jacek; Janicki, Damian; Fidali, Marek; Jamrozik, Wojciech

2017-12-01

Thermomechanically processed steels are materials of great mechanical properties connected with more than good weldability. This mixture makes them interesting for different types of industrial applications. When creating welded joints, a specified amount of heat is introduced into the welding area and a so called heat-affected zone (HAZ) is formed. The key issue is to reduce the width of the HAZ, because properties of the material in the HAZ are worse than in the base material. In the paper, thermographic measurements of HAZ temperatures were presented as a potential tool for quality assuring the welding process in terms of monitoring and control. The main issue solved was the precise temperature measurement in terms of varying emissivity during a welding thermal cycle. A model of emissivity changes was elaborated and successfully applied. Additionally, material in the HAZ was tested to reveal its properties and connect changes of those properties with heating parameters. The obtained results prove that correctly modeled emissivity allows measurement of temperature, which is a valuable tool for welding process monitoring.

Development of procedures for calculating stiffness and damping properties of elastomers. Part 3: The effects of temperature, dissipation level and geometry

NASA Technical Reports Server (NTRS)

Smalley, A. J.; Tessarzik, J. M.

1975-01-01

Effects of temperature, dissipation level and geometry on the dynamic behavior of elastomer elements were investigated. Force displacement relationships in elastomer elements and the effects of frequency, geometry and temperature upon these relationships are reviewed. Based on this review, methods of reducing stiffness and damping data for shear and compression test elements to material properties (storage and loss moduli) and empirical geometric factors are developed and tested using previously generated experimental data. A prediction method which accounts for large amplitudes of deformation is developed on the assumption that their effect is to increase temperature through the elastomers, thereby modifying the local material properties. Various simple methods of predicting the radial stiffness of ring cartridge elements are developed and compared. Material properties were determined from the shear specimen tests as a function of frequency and temperature. Using these material properties, numerical predictions of stiffness and damping for cartridge and compression specimens were made and compared with corresponding measurements at different temperatures, with encouraging results.

Review on supplymentary cementitious materials used in inorganic polymer concrete

NASA Astrophysics Data System (ADS)

Srinivasreddy, K.; Srinivasan, K.

2017-11-01

This paper presents a review on various supplementary cementitious materials generated from industries are used in concrete, which one is considered a waste material. These materials are rich in aluminosilicates and are activated by sodium/potassium based alkaline solution to form geopolymer concrete. When these geopolymer concrete is used in civil engineering applications has showed better or similar mechanical properties and durability properties than ordinary Portland cement concrete. This paper also given the overview on sodium hydroxide (NaOH) & sodium silicate solution (Na2SiO3) ratios, curing adopted for different geopolymer concretes and the effect of adding fibres in geopolymer concretes.

Direct comparison of nanoindentation and tensile test results on reactor-irradiated materials

NASA Astrophysics Data System (ADS)

Krumwiede, D. L.; Yamamoto, T.; Saleh, T. A.; Maloy, S. A.; Odette, G. R.; Hosemann, P.

2018-06-01

Nanoindentation testing has been used for decades to assess materials on a local scale and to obtain fundamental mechanical property parameters. Nuclear materials research often faces the challenge of testing rather small samples due to the hazardous nature, limited space in reactors, and shallow ion-irradiated zones, fostering the need for small-scale mechanical testing (SSMT). As such, correlating the results from SSMT to bulk properties is particularly of interest. This study compares macroscopic tensile test data (yield and flow stresses) to nanoindentation data (hardness) obtained on a number of different neutron-irradiated materials in order to understand the scaling behavior on radiation-damaged samples.

Mechanical properties evaluation of extruded wood polymer composites

NASA Astrophysics Data System (ADS)

Zaini, A. S. Syah M.; Rus, Anika Zafiah M.; Rahman, Norherman Abdul; Jais, Farhana Hazwanee M.; Fauzan, M. Zarif; Sufian, N. Afiqah

2017-09-01

The rapidly expanding of interest in the manufacture of composite materials from waste industrial and agricultural materials is due to high demand for environmentally friendly materials. Wood polymer composite (WPC) are being used in many type of applications such as in the automobile, electronic, aerospace industry and construction. Therefore, this research study is to determine the mechanical properties behaviour of WPC after an extended Ultra Violet (UV) irradiation exposure. The fabricated sample has been used and to be compared in this research is consists of rice husk, waste fibre and polypropylene (PP) with 4 different types of WPC which are wood block waste (WBW), wood block virgin (WBV), wood sheet (WS) and wood sheet waste (WSW). The extruded specimens were tested for mechanical properties such as strength under compression, puncture strength and impact resistance, and density. In addition, the specimen has been irradiated with the UV exposure at 5000 hours, 10000 hours and 15000 hours. Generally, the mechanical properties the WPC which made from the recycled material were lower than the WPC from virgin material but the density was comparable between the two products after UV irradiation exposure.

Nanomaterial characterization: considerations and needs for hazard assessment and safety evaluation.

PubMed

Boverhof, Darrell R; David, Raymond M

2010-02-01

Nanotechnology is a rapidly emerging field of great interest and promise. As new materials are developed and commercialized, hazard information also needs to be generated to reassure regulators, workers, and consumers that these materials can be used safely. The biological properties of nanomaterials are closely tied to the physical characteristics, including size, shape, dissolution rate, agglomeration state, and surface chemistry, to name a few. Furthermore, these properties can be altered by the medium used to suspend or disperse these water-insoluble particles. However, the current toxicology literature lacks much of the characterization information that allows toxicologists and regulators to develop "rules of thumb" that could be used to assess potential hazards. To effectively develop these rules, toxicologists need to know the characteristics of the particle that interacts with the biological system. This void leaves the scientific community with no options other than to evaluate all materials for all potential hazards. Lack of characterization could also lead to different laboratories reporting discordant results on seemingly the same test material because of subtle differences in the particle or differences in the dispersion medium used that resulted in altered properties and toxicity of the particle. For these reasons, good characterization using a minimal characterization data set should accompany and be required of all scientific publications on nanomaterials.

Impact of Aggregates Size and Fibers on basic Mechanical Properties of Asphalt Emulsion—Cement Concrete

NASA Astrophysics Data System (ADS)

Fu, Jun; Liu, Zhihong; Liu, Jie

2018-01-01

Asphalt Emulsion—Cement Concrete (AECC) is currently considered as a typical semi-flexibility material. One of the disadvantages of this material is brittle fracture and lacking ductility. This study aims at accelerating the basic mechanical properties of AECC using fibers and different aggregates size. The mix of AECC was introduced and the different content of fibers and aggregates size were studied. The results showed that the smaller aggregates size could improve the young’s modulus and compressive strength as well as fiber. The modulus-compressive strength ratio of fiber reinforced AECC is always below 500.

Resonant halide perovskite nanoparticles

NASA Astrophysics Data System (ADS)

Tiguntseva, Ekaterina Y.; Ishteev, Arthur R.; Komissarenko, Filipp E.; Zuev, Dmitry A.; Ushakova, Elena V.; Milichko, Valentin A.; Nesterov-Mueller, Alexander; Makarov, Sergey V.; Zakhidov, Anvar A.

2017-09-01

The hybrid halide perovskites is a prospective material for fabrication of cost-effective optical devices. Unique perovskites properties are used for solar cells and different photonic applications. Recently, perovskite-based nanophotonics has emerged. Here, we consider perovskite like a high-refractive index dielectric material, which can be considered to be a basis for nanoparticles fabrication with Mie resonances. As a result, we fabricate and study resonant perovskite nanoparticles with different sizes. We reveal, that spherical nanoparticles show enhanced photoluminescence signal. The achieved results lay a cornerstone in the field of novel types of organic-inorganic nanophotonics devices with optical properties improved by Mie resonances.

Effect of Extrusion on the Mechanical and Rheological Properties of a Reinforced Poly(Lactic Acid): Reprocessing and Recycling of Biobased Materials.

PubMed

Peinado, Víctor; Castell, Pere; García, Lidia; Fernández, Ángel

2015-10-19

The aim of this research paper is to study the behaviour of a common used biopolymer (Poly(Lactic Acid) (PLA)) after several reprocesses and how two different types of additives (a melt strength enhancer and a nanoadditive) affect its mechanical and rheological properties. Systematic extraction of extrudate samples from a twin-screw compounder was done in order to study the effect in the properties of the reprocessed material. Detailed rheological tests on a capillary rheometer as well as mechanical studies on a universal tensile machine after preparation of injected specimens were carried out. Results evidenced that PLA and reinforced PLA materials can be reprocessed and recycled without a remarkable loss in their mechanical properties. Several processing restrictions and specific phenomena were identified and are explained in the present manuscript.

Mechanical behaviour of degradable phosphate glass fibres and composites-a review.

PubMed

Colquhoun, R; Tanner, K E

2015-12-23

Biodegradable materials are potentially an advantageous alternative to the traditional metallic fracture fixation devices used in the reconstruction of bone tissue defects. This is due to the occurrence of stress shielding in the surrounding bone tissue that arises from the absence of mechanical stimulus to the regenerating bone due to the mismatch between the elastic modulus of bone and the metal implant. However although degradable polymers may alleviate such issues, these inert materials possess insufficient mechanical properties to be considered as a suitable alternative to current metallic devices at sites of sufficient mechanical loading. Phosphate based glasses are an advantageous group of materials for tissue regenerative applications due to their ability to completely degrade in vivo at highly controllable rates based on the specific glass composition. Furthermore the release of the glass's constituent ions can evoke a therapeutic stimulus in vivo (i.e. osteoinduction) whilst also generating a bioactive response. The processing of these materials into fibres subsequently allows them to act as reinforcing agents in degradable polymers to simultaneously increase its mechanical properties and enhance its in vivo response. However despite the various review articles relating to the compositional influences of different phosphate glass systems, there has been limited work summarising the mechanical properties of different phosphate based glass fibres and their subsequent incorporation as a reinforcing agent in degradable composite materials. As a result, this review article examines the compositional influences behind the development of different phosphate based glass fibre compositions intended as composite reinforcing agents along with an analysis of different potential composite configurations. This includes variations in the fibre content, matrix material and fibre architecture as well as other novel composites designs.

Recyclability assessment of nano-reinforced plastic packaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sánchez, C., E-mail: csanchez@itene.com; Hortal, M., E-mail: mhortal@itene.com; Aliaga, C., E-mail: caliaga@itene.com

2014-12-15

Highlights: • The study compares the recyclability of polymers with and without nanoparticles. • Visual appearance, material quality and mechanical properties are evaluated. • Minor variations in mechanical properties in R-PE and R-PP with nanoparticles. • Slight degradation of R-PET which affect mechanical properties. • Colour deviations in recycled PE, PP and PET in ranges higher that 0.3 units. - Abstract: Packaging is expected to become the leading application for nano-composites by 2020 due to the great advantages on mechanical and active properties achieved with these substances. As novel materials, and although there are some current applications in the market,more » there is still unknown areas under development. One key issue to be addressed is to know more about the implications of the nano-composite packaging materials once they become waste. The present study evaluates the extrusion process of four nanomaterials (Layered silicate modified nanoclay (Nanoclay1), Calcium Carbonate (CaCO{sub 3}), Silver (Ag) and Zinc Oxide (ZnO) as part of different virgin polymer matrices of polyethylene (PE), Polypropylene (PP) and Polyethyleneterephtalate (PET). Thus, the following film plastic materials: (PE–Nanoclay1, PE–CaCO{sub 3}, PP–Ag, PET–ZnO, PET–Ag, PET–Nanoclay1) have been processed considering different recycling scenarios. Results on recyclability show that for PE and PP, in general terms and except for some minor variations in yellowness index, tensile modulus, tensile strength and tear strength (PE with Nanoclay1, PP with Ag), the introduction of nanomaterial in the recycling streams for plastic films does not affect the final recycled plastic material in terms of mechanical properties and material quality compared to conventional recycled plastic. Regarding PET, results show that the increasing addition of nanomaterial into the recycled PET matrix (especially PET–Ag) could influence important properties of the recycled material, due to a slight degradation of the polymer, such as increasing pinholes, degradation fumes and elongation at break. Moreover, it should be noted that colour deviations were visible in most of the samples (PE, PP and PET) in levels higher than 0.3 units (limit perceivable by the human eye). The acceptance of these changes in the properties of recycled PE, PP and PET will depend on the specific applications considered (e.g. packaging applications are more strict in material quality that urban furniture or construction products)« less

Behavior of auxetic structures under compression and impact forces

NASA Astrophysics Data System (ADS)

Yang, Chulho; Vora, Hitesh D.; Chang, Young

2018-02-01

In recent years, various auxetic material structures have been designed and fabricated for diverse applications that utilize normal materials that follow Hooke’s law but still show the properties of negative Poisson’s ratios (NPR). One potential application is body protection pads that are comfortable to wear and effective in protecting body parts by reducing impact force and preventing injuries in high-risk individuals such as elderly people, industrial workers, law enforcement and military personnel, and athletes. This paper reports an integrated theoretical, computational, and experimental investigation conducted for typical auxetic materials that exhibit NPR properties. Parametric 3D CAD models of auxetic structures such as re-entrant hexagonal cells and arrowheads were developed. Then, key structural characteristics of protection pads were evaluated through static analyses of FEA models. Finally, impact analyses were conducted through dynamic simulations of FEA models to validate the results obtained from the static analyses. Efforts were also made to relate the individual and/or combined effect of auxetic structures and materials to the overall stiffness and shock-absorption performance of the protection pads. An advanced additive manufacturing (3D printing) technique was used to build prototypes of the auxetic structures. Three different materials typically used for fused deposition modeling technology, namely polylactic acid (PLA) and thermoplastic polyurethane material (NinjaFlex® and SemiFlex®), were used for different stiffness and shock-absorption properties. The 3D printed prototypes were then tested and the results were compared to the computational predictions. The results showed that the auxetic material could be effective in reducing the shock forces. Each structure and material combination demonstrated unique structural properties such as stiffness, Poisson’s ratio, and efficiency in shock absorption. Auxetic structures showed better shock absorption performance than non-auxetic ones. The mechanism for ideal input force distribution or shunting could be suggested for designing protectors using various shapes, thicknesses, and materials of auxetic materials to reduce the risk of injury.

Tensile Properties of Polymeric Matrix Composites Subjected to Cryogenic Environments

NASA Technical Reports Server (NTRS)

Whitley, Karen S.; Gates, Thomas S.

2004-01-01

Polymer matrix composites (PMC s) have seen limited use as structural materials in cryogenic environments. One reason for the limited use of PMC s in cryogenic structures is a design philosophy that typically requires a large, validated database of material properties in order to ensure a reliable and defect free structure. It is the intent of this paper to provide an initial set of mechanical properties developed from experimental data of an advanced PMC (IM7/PETI-5) exposed to cryogenic temperatures and mechanical loading. The application of this data is to assist in the materials down-select and design of cryogenic fuel tanks for future reusable space vehicles. The details of the material system, test program, and experimental methods will be outlined. Tension modulus and strength were measured at room temperature, -196 C, and -269 C on five different laminates. These properties were also tested after aging at -186 C with and without loading applied. Microcracking was observed in one laminate.

Enhancement in biological response of Ag-nano composite polymer membranes using plasma treatment for fabrication of efficient bio materials

NASA Astrophysics Data System (ADS)

Agrawal, Narendra Kumar; Sharma, Tamanna Kumari; Chauhan, Manish; Agarwal, Ravi; Vijay, Y. K.; Swami, K. C.

2016-05-01

Biomaterials are nonviable material used in medical devices, intended to interact with biological systems, which are becoming necessary for the development of artificial material for biological systems such as artificial skin diaphragm, valves for heart and kidney, lenses for eye etc. Polymers having novel properties like antibacterial, antimicrobial, high adhesion, blood compatibility and wettability are most suitable for synthesis of biomaterial, but all of these properties does not exist in any natural or artificial polymeric material. Nano particles and plasma treatment can offer these properties to the polymers. Hence a new nano-biomaterial has been developed by modifying the surface and chemical properties of Ag nanocomposite polymer membranes (NCPM) by Argon ion plasma treatment. These membranes were characterized using different techniques for surface and chemical modifications occurred. Bacterial adhesion and wettability were also tested for these membranes, to show direct use of this new class of nano-biomaterial for biomedical applications.

Physical properties of a new sonically placed composite resin restorative material.

PubMed

Ibarra, Emily T; Lien, Wen; Casey, Jeffery; Dixon, Sara A; Vandewalle, Kraig S

2015-01-01

A new nanohybrid composite activated by sonic energy has been recently introduced as a single-step, bulk-fill restorative material. The purpose of this study was to compare the physical properties of this new composite to various other composite restorative materials marketed for posterior or bulk-fill placement. The following physical properties were examined: depth of cure, volumetric shrinkage, flexural strength, flexural modulus, fracture toughness, and percent porosity. A mean and standard deviation were determined per group. One-way ANOVA and Tukey's post hoc tests were performed per property (α = 0.05). Percent porosity was evaluated with a Kruskal-Wallis/Mann-Whitney test (α = 0.005). Significant differences were found between groups (P < 0.001) per test type. Compared to the other composite restorative materials, the new nanohybrid composite showed low shrinkage and percent porosity, moderate fracture toughness and flexural modulus, and high flexural strength. However, it also demonstrated a relatively reduced depth of cure compared to the other composites.

Properties and degradation of the gasket component of a proton exchange membrane fuel cell--a review.

PubMed

Basuli, Utpal; Jose, Jobin; Lee, Ran Hee; Yoo, Yong Hwan; Jeong, Kwang-Un; Ahn, Jou-Hyeon; Nah, Changwoon

2012-10-01

Proton exchange membrane (PEM) fuel cell stack requires gaskets and seals in each cell to keep the reactant gases within their respective regions. Gasket performance is integral to the successful long-term operation of a fuel cell stack. This review focuses on properties, performance and degradation mechanisms of the different polymer gasket materials used in PEM fuel cell under normal operating conditions. The different degradation mechanisms and their corresponding representative mitigation strategies are also presented here. Summary of various properties of elastomers and their advantages and disadvantages in fuel cell'environment are presented. By considering the level of chemical degradation, mechanical properties and cost effectiveness, it can be proposed that EPDM is one of the best choices for gasket material in PEM fuel cell. Finally, the challenges that remain in using rubber component as in PEM fuel cell, as well as the prospects for exploiting them in the future are discussed.

Iosipescu shear properties of graphite fabric/epoxy composite laminates

NASA Technical Reports Server (NTRS)

Walrath, D. E.; Adams, D. F.

1985-01-01

The Iosipescu shear test method is used to measure the in-plane and interlaminar shear properties of four T300 graphite fabric/934 epoxy composite materials. Different weave geometries tested include an Oxford weave, a 5-harness satin weave, an 8-harness satin weave, and a plain weave with auxiliary warp yarns. Both orthogonal and quasi-isotropic layup laminates were tested. In-plane and interlaminar shear properties are obtained for laminates of all four fabric types. Overall, little difference in shear properties attributable to the fabric weave pattern is observed. The auxiliary warp material is significantly weaker and less stiff in interlaminar shear parallel to its fill direction. A conventional strain gage extensometer is modified to measure shear strains for use with the Iosipescu shear test. While preliminary results are encouraging, several design iterations failed to produce a reliable shear transducer prototype. Strain gages are still the most reliable shear strain transducers for use with this test method.

Effect of different fibers on mechanical properties and ductility of alkali-activated slag cementitious material

NASA Astrophysics Data System (ADS)

Zhu, J.; Zheng, W. Z.; Qin, C. Z.; Xu, Z. Z.; Wu, Y. Q.

2018-01-01

The effect of different fibers on mechanical properties and ductility of alkali-activated slag cementitious material (AASCM) is studied. The research contents include: fiber type (plant fiber, polypropylene fiber), fiber content, mechanical property index, tensile stress-strain relationship curve, treating time. The test results showed that the compressive strength of two fibers reinforced AASCM was about 90 ~ 110MPa, and the tensile strength was about 3 ~ 5MPa. The reinforcement effect of polypropylene fiber is superior to that of plant fiber, and the mechanical properties of polypropylene fiber reinforced AASCM are superior to those of plant fiber, According to the comparison of SEM pictures, the plant fiber and polypropylene fiber are both closely bound with the matrix, and the transition zones are complete and close. Thus, it is proved that plant fiber and polypropylene fiber delay the crack extension and enhance the ductility of AASCM.

Classification-free threat detection based on material-science-informed clustering

NASA Astrophysics Data System (ADS)

Yuan, Siyang; Wolter, Scott D.; Greenberg, Joel A.

2017-05-01

X-ray diffraction (XRD) is well-known for yielding composition and structural information about a material. However, in some applications (such as threat detection in aviation security), the properties of a material are more relevant to the task than is a detailed material characterization. Furthermore, the requirement that one first identify a material before determining its class may be difficult or even impossible for a sufficiently large pool of potentially present materials. We therefore seek to learn relevant composition-structure-property relationships between materials to enable material-identification-free classification. We use an expert-informed, data-driven approach operating on a library of XRD spectra from a broad array of stream of commerce materials. We investigate unsupervised learning techniques in order to learn about naturally emergent groupings, and apply supervised learning techniques to determine how well XRD features can be used to separate user-specified classes in the presence of different types and degrees of signal degradation.

Effect of Polymer Form and its Consolidation on Mechanical Properties and Quality of Glass/PBT Composites

NASA Astrophysics Data System (ADS)

Durai Prabhakaran, R. T.; Pillai, Saju; Charca, Samuel; Oshkovr, Simin Ataollahi; Knudsen, Hans; Andersen, Tom Løgstrup; Bech, Jakob Ilsted; Thomsen, Ole Thybo; Lilholt, Hans

2014-04-01

The aim of this study was to understand the role of the processing in determining the mechanical properties of glass fibre reinforced polybutylene terephthalate composites (Glass/PBT). Unidirectional (UD) composite laminates were manufactured by the vacuum consolidation technique using three different material systems included in this study; Glass/CBT (CBT160 powder based resin), Glass/PBT (prepreg tapes), and Glass/PBT (commingled yarns). The different types of thermoplastic polymer resin systems used for the manufacturing of the composite UD laminate dictate the differences in final mechanical properties which were evaluated by through compression, flexural and short beam transverse bending tests. Microscopy was used to evaluate the quality of the processed laminates, and fractography was used to characterize the observed failure modes. The study provides an improved understanding of the relationships between processing methods, resin characteristics, and mechanical performance of thermoplastic resin composite materials.

Commercially pure titanium (cp-Ti) versus titanium alloy (Ti6Al4V) materials as bone anchored implants - Is one truly better than the other?

PubMed

Shah, Furqan A; Trobos, Margarita; Thomsen, Peter; Palmquist, Anders

2016-05-01

Commercially pure titanium (cp-Ti) and titanium alloys (typically Ti6Al4V) display excellent corrosion resistance and biocompatibility. Although the chemical composition and topography are considered important, the mechanical properties of the material and the loading conditions in the host have, conventionally, influenced material selection for different clinical applications: predominantly Ti6Al4V in orthopaedics while cp-Ti in dentistry. This paper attempts to address three important questions: (i) To what extent do the surface properties differ when cp-Ti and Ti6Al4V materials are manufactured with the same processing technique?, (ii) Does bone tissue respond differently to the two materials, and (iii) Do bacteria responsible for causing biomaterial-associated infections respond differently to the two materials? It is concluded that: (i) Machined cp-Ti and Ti6Al4V exhibit similar surface morphology, topography, phase composition and chemistry, (ii) Under experimental conditions, cp-Ti and Ti6Al4V demonstrate similar osseointegration and biomechanical anchorage, and (iii) Experiments in vitro fail to disclose differences between cp-Ti and Ti6Al4V to harbour Staphylococcus epidermidis growth. No clinical comparative studies exist which could determine if long-term, clinical differences exist between the two types of bulk materials. It is debatable whether cp-Ti or Ti6Al4V exhibit superiority over the other, and further comparative studies, particularly in a clinical setting, are required. Copyright © 2016 Elsevier B.V. All rights reserved.

Thermodynamic and structural insights into nanocomposites engineering by comparing two materials assembly techniques for graphene.

PubMed

Zhu, Jian; Zhang, Huanan; Kotov, Nicholas A

2013-06-25

Materials assembled by layer-by-layer (LBL) assembly and vacuum-assisted flocculation (VAF) have similarities, but a systematic study of their comparative advantages and disadvantages is missing. Such a study is needed from both practical and fundamental perspectives aiming at a better understanding of structure-property relationships of nanocomposites and purposeful engineering of materials with unique properties. Layered composites from polyvinyl alcohol (PVA) and reduced graphene (RG) are made by both techniques. We comparatively evaluate their structure, mechanical, and electrical properties. LBL and VAF composites demonstrate clear differences at atomic and nanoscale structural levels but reveal similarities in micrometer and submicrometer organization. Epitaxial crystallization and suppression of phase transition temperatures are more pronounced for PVA in LBL than for VAF composites. Mechanical properties are virtually identical for both assemblies at high RG contents. We conclude that mechanical properties in layered RG assemblies are largely determined by the thermodynamic state of PVA at the polymer/nanosheet interface rather than the nanometer scale differences in RG packing. High and nearly identical values of toughness for LBL and VAF composites reaching 6.1 MJ/m(3) observed for thermodynamically optimal composition confirm this conclusion. Their toughness is the highest among all other layered assemblies from RG, cellulose, clay, etc. Electrical conductivity, however, is more than 10× higher for LBL than for VAF composites for the same RG contents. Electrical properties are largely determined by the tunneling barrier between RG sheets and therefore strongly dependent on atomic/nanoscale organization. These findings open the door for application-oriented methods of materials engineering using both types of layered assemblies.

Evaluation of material properties and compression characteristics of Assam Bora rice flours as a directly compressible vehicle in tablet formulation.

PubMed

Ahmad, Mohammad Zaki; Akhter, Sohail; Dhiman, Ishita; Sharma, Poonam; Verma, Reena

2013-02-01

The mechanical properties and compaction characteristics of different varieties of Assam Bora rice flours (ABRFs) were evaluated and compared with those of official Starch 1500®. The material properties and compression characteristics of Assam Bora rice flours were studied by Heckel and Kawakita analysis. The influences of physical and geometrical properties of ABRFs were evaluated with regard to their compression properties. The mechanical properties, such as toughness and Young's modulus of ABRFs were also compared with that of Starch 1500®. The novel ABRFs reflect better physical characteristics such as higher bulk and tap densities, less porosity, better powder packing ability, large surface area, and improved flowability. ABRFs were the least sensitive material to magnesium stearate, and blending time did not affect its compactibility. Their onset of plastic deformation and strain rate sensitivity as compared to that of Starch 1500® demonstrate its potential use as a directly compressible vehicle for tablet. The experimental ABRFs showed superior properties to official Starch 1500® in many cases and could serve as suitable alternatives for particular purposes.

Towards Rational Design of Functional Fluoride and Oxyfluoride Materials from First Principles

NASA Astrophysics Data System (ADS)

Charles, Nenian

Complex transition metal compounds (TMCs) research has produced functional materials with a range of properties, including ferroelectricity, colossal magnetoresistance, nonlinear optical activity and high-temperature superconductivity. Conventional routes to tune properties in transition metal oxides, for example, have relied primarily on cation chemical substitution and interfacial effects in thin film heterostructures. In heteroanionic TMCs, exhibiting two chemically distinct anions coordinating the same or different cations, engineering of the anion sub-lattice for property control is a promising alternative approach. The presence of multiple anions provides additional design variables, such as anion order, that are absent in homoanionic counterparts. The more complex structural and chemical phase space of heteroanionic materials provides a unique opportunity to realize enhanced or unanticipated electronic, optical, and magnetic responses. Although there is growing interest in heteroanionic materials, and synthetic and characterization advances are occurring for these materials, the crystal-chemistry principles for realizing structural and property control are only slowing emerging. This dissertation employs anion engineering to investigate phenomena in transition metal fluorides and oxyfluorides compounds using first principles density functional theory calculations. Oxyfluorides are particularly intriguing owing their tendency to stabilize highly ordered anion sublattices as well as the potential to combine the advantageous properties of transition metal oxides and fluorides. This work 1) addresses the challenges of studying fluorides and oxyfluorides using first principles calculations; 2) evaluates the feasibility of using external stimuli, such as epitaxial strain and hydrostatic pressure, to control properties of fluorides and oxyfluorides; and 3) formulates a computational workflow based on multiple levels of theory and computation to elucidate structure-property relationships and anion-order descriptors. The insights gained in this work advance the understanding of oxide-fluoride anion engineered materials and we anticipate that it will motivate novel experimental efforts and materials by design in the future.

A Study on the Mechanical Properties and Impact-Induced Initiation Characteristics of Brittle PTFE/Al/W Reactive Materials.

PubMed

Ge, Chao; Maimaitituersun, Wubuliaisan; Dong, Yongxiang; Tian, Chao

2017-04-26

Polytetrafluoroethylene/aluminum/tungsten (PTFE/Al/W) reactive materials of three different component mass ratios (73.5/26.5/0, 68.8/24.2/7 and 63.6/22.4/14) were studied in this research. Different from the PTFE/Al/W composites published elsewhere, the materials in our research were fabricated under a much lower sintering temperature and for a much shorter duration to achieve a brittle property, which aims to provide more sufficient energy release upon impact. Quasi-static compression tests, dynamic compression tests at room and elevated temperatures, and drop weight tests were conducted to evaluate the mechanical and impact-induced initiation characteristics of the materials. The materials before and after compression tests were observed by a scanning electron microscope to relate the mesoscale structural characteristics to their macro properties. All the three types of materials fail at very low strains during both quasi-static and dynamic compression. The stress-strain curves for quasi-static tests show obvious deviations while that for the dynamic tests consist of only linear-elastic and failure stages typically. The materials were also found to exhibit thermal softening at elevated temperatures and were strain-rate sensitive during dynamic tests, which were compared using dynamic increase factors (DIFs). Drop-weight test results show that the impact-initiation sensitivity increases with the increase of W content due to the brittle mechanical property. The high-speed video sequences and recovered sample residues of the drop-weight tests show that the reaction is initiated at two opposite positions near the edges of the samples, where the shear force concentrates the most intensively, indicating a shear-induced initiation mechanism.

A Study on the Mechanical Properties and Impact-Induced Initiation Characteristics of Brittle PTFE/Al/W Reactive Materials

PubMed Central

Ge, Chao; Maimaitituersun, Wubuliaisan; Dong, Yongxiang; Tian, Chao

2017-01-01

Polytetrafluoroethylene/aluminum/tungsten (PTFE/Al/W) reactive materials of three different component mass ratios (73.5/26.5/0, 68.8/24.2/7 and 63.6/22.4/14) were studied in this research. Different from the PTFE/Al/W composites published elsewhere, the materials in our research were fabricated under a much lower sintering temperature and for a much shorter duration to achieve a brittle property, which aims to provide more sufficient energy release upon impact. Quasi-static compression tests, dynamic compression tests at room and elevated temperatures, and drop weight tests were conducted to evaluate the mechanical and impact-induced initiation characteristics of the materials. The materials before and after compression tests were observed by a scanning electron microscope to relate the mesoscale structural characteristics to their macro properties. All the three types of materials fail at very low strains during both quasi-static and dynamic compression. The stress-strain curves for quasi-static tests show obvious deviations while that for the dynamic tests consist of only linear-elastic and failure stages typically. The materials were also found to exhibit thermal softening at elevated temperatures and were strain-rate sensitive during dynamic tests, which were compared using dynamic increase factors (DIFs). Drop-weight test results show that the impact-initiation sensitivity increases with the increase of W content due to the brittle mechanical property. The high-speed video sequences and recovered sample residues of the drop-weight tests show that the reaction is initiated at two opposite positions near the edges of the samples, where the shear force concentrates the most intensively, indicating a shear-induced initiation mechanism. PMID:28772812

Impact of the interaction of material production and mechanical processing on the magnetic properties of non-oriented electrical steel

NASA Astrophysics Data System (ADS)

Leuning, Nora; Steentjes, Simon; Stöcker, Anett; Kawalla, Rudolf; Wei, Xuefei; Dierdorf, Jens; Hirt, Gerhard; Roggenbuck, Stefan; Korte-Kerzel, Sandra; Weiss, Hannes A.; Volk, Wolfram; Hameyer, Kay

2018-04-01

Thin laminations of non-grain oriented (NO) electrical steels form the magnetic core of rotating electrical machines. The magnetic properties of these laminations are therefore key elements for the efficiency of electric drives and need to be fully utilized. Ideally, high magnetization and low losses are realized over the entire polarization and frequency spectrum at reasonable production and processing costs. However, such an ideal material does not exist and thus, achievable magnetic properties need to be deduced from the respective application requirements. Parameters of the electrical steel such as lamination thickness, microstructure and texture affect the magnetic properties as well as their polarization and frequency dependence. These structural features represent possibilities to actively alter the magnetic properties, e.g., magnetization curve, magnetic loss or frequency dependence. This paper studies the influence of production and processing on the resulting magnetic properties of a 2.4 wt% Si electrical steel. Aim is to close the gap between production influence on the material properties and its resulting effect on the magnetization curves and losses at different frequencies with a strong focus on occurring interdependencies between production and mechanical processing. The material production is realized on an experimental processing route that comprises the steps of hot rolling, cold rolling, annealing and punching.

Theoretical backgrounds of non-tempered materials production based on new raw materials

NASA Astrophysics Data System (ADS)

Lesovik, V. S.; Volodchenko, A. A.; Glagolev, E. S.; Chernysheva, N. V.; Lashina, I. V.; Feduk, R. S.

2018-03-01

One of the trends in construction material science is development and implementation of highly effective finish materials which improve architectural exterior of cities. Silicate materials widely-used in the construction today have rather low decorative properties. Different coloring agents are used in order to produce competitive materials, but due to the peculiarities of the production, process very strict specifications are applied to them. The use of industrial wastes or variety of rock materials as coloring agents is of great interest nowadays. The article shows that clay rock can be used as raw material in production of finish materials of non-autoclaved solidification. This raw material due to its material composition actively interacts with cementing component in steam treatment at 90–95 °C with formation of cementing joints that form a firm coagulative-cristalized and crystallization structure of material providing high physic-mechanical properties of silicate goods. It is determined that energy-saving, colored finish materials with compression strength up to 16 MPa can be produced from clay rocks.

Volume imaging NDE and serial sectioning of carbon fiber composites

NASA Astrophysics Data System (ADS)

Hakim, Issa; Schumacher, David; Sundar, Veeraraghavan; Donaldson, Steven; Creuz, Aline; Schneider, Rainer; Keller, Juergen; Browning, Charles; May, Daniel; Ras, Mohamad Abo; Meyendorf, Norbert

2018-04-01

A composite material is a combination of two or more materials with very different mechanical, thermal and electrical properties. The various forms of composite materials, due to their high material properties, are widely used as structural materials in the aviation, space, marine, automobile, and sports industries. However, some defects like voids, delamination, or inhomogeneous fiber distribution that form during the fabricating processes of composites can seriously affect the mechanical properties of the composite material. In this study, several imaging NDE techniques such as: thermography, high frequency eddy current, ultrasonic, x-ray radiography, x-ray laminography, and high resolution x-ray CT were conducted to characterize the microstructure of carbon fiber composites. Then, a 3D analysis was implemented by the destructive technique of serial sectioning for the same sample tested by the NDE methods. To better analyze the results of this work and extract a clear volume image for all features and defects contained in the composite material, an intensive comparison was conducted among hundreds of 3D-NDE and multi serial sections' scan images showing the microstructure variation.

The properties of weft knitted fabric medical and preventive treatment action using eco-raw materials

NASA Astrophysics Data System (ADS)

Halavska, L.; Batrak, O.

2016-07-01

A new trend in the world is the clothing production using the new types of ecological raw materials application - milk, pineapple, coconut, hemp, banana, eucalyptus, clams, corn, bamboo, soya, nettle yarn. This makes it possible to create textile materials of new generation with unique antibacterial and antiseptic properties. Such materials have a positive preventive and sometimes therapeutic effect on people, and their health. Eco-raw materials clothing is able to protect the human body from the environment harmful effects: cold, heat, rain, dust, opportunely remove from underclothing layer the steam and gases, sweat; maintain in underclothing layer the necessary microclimate for normal organism functioning. Study of knitwear consumer properties, produced with eco-materials, is an urgent task of the world vector, directed on ecological environmental protection. This paper presents the research results of hygroscopicity and capillarity weft knitted fabrics, what knitted from different types of eco-raw materials: bamboo yarn, yarn containing soybean and nettle yarn. Character of influence of the liquid raising level changes depending on the experiment time and the knitting structure is revealed.

Spectroscopic investigations upon 100MeV oxygen ions irradiation on polyaniline and poly-o-toluidine

NASA Astrophysics Data System (ADS)

Patil, Harshada K.; Deshmukh, Megha A.; Bodkhe, Gajanan A.; Asokan, K.; Shirsat, Mahendra D.

2018-05-01

Conducting polymers are the materials been extensively studied in the field of organic devise applications. The extended π-orbital which enables electron to move from one to another end of polymer made it flexible in tailoring different properties and therefore are known to be the considerably attractive materials. Here in this report Polyaniline (PANI) and Poly-o-toluidine (PoT) the derivative of PANI where one hydrogen atom of main polymer chain is substituted with the methyl group are studied upon irradiation with 100MeV oxygen ions irradiation at different fluences. PANI and PoT consist of interesting properties viz. electrochemical and optical properties, moderate conductivity, as well as environmental stability, may be applicable to the chemical sensing applications. Swift Heavy Ions (SHI) irradiation is the exclusively applied tool in detrimental modifications of solid materials. The effects of SHI irradiation on PANI and PoT were studied using UV - Vis spectroscopy and Raman spectroscopy. The band gap studies were done with Tauc plot calculations.

Modified polyether-sulfone membrane: a mini review

PubMed Central

Alenazi, Noof A.; Hussein, Mahmoud A.; Alamry, Khalid A.; Asiri, Abdullah M.

2017-01-01

Abstract Polyethersulfone has been widely used as a promising material in medical applications and waste-treatment membranes since it provides excellent mechanical and thermal properties. Hydrophobicity of polyethersulfone is considered one main disadvantage of using this material because hydrophobic surface causes biofouling effects to the membrane which is always thought to be a serious limitation to the use of polyethersulfone in membrane technology. Chemical modification to the material is a promising solution to this problem. More specifically surface modification is an excellent technique to introduce hydrophilic properties and functional groups to the polyethersulfone membrane surface. This review covers chemical modifications of the polyethersulfone and covers different methods used to enhance the hydrophilicity of polyethersulfone membrane. In particular, the addition of amino functional groups to polyethersulfone is used as a fundamental method either to introduce hydrophilic properties or introduce nanomaterials to the surface of polyethersulfone membrane. This work reviews also previous research reports explored the use of amino functionalized polyethersulfone with different nanomaterials to induce biological activity and reduce fouling effects of the fabricated membrane. PMID:29491825

3D porous polyurethanes featured by different mechanical properties: Characterization and interaction with skeletal muscle cells.

PubMed

Vannozzi, Lorenzo; Ricotti, Leonardo; Santaniello, Tommaso; Terencio, Tercio; Oropesa-Nunez, Reinier; Canale, Claudio; Borghi, Francesca; Menciassi, Arianna; Lenardi, Cristina; Gerges, Irini

2017-11-01

The fabrication of biomaterials for interaction with muscle cells has attracted significant interest in the last decades. However, 3D porous scaffolds featured by a relatively low stiffness (almost matching the natural muscle one) and highly stable in response to cyclic loadings are not available at present, in this context. This work describes 3D polyurethane-based porous scaffolds featured by different mechanical properties. Biomaterial stiffness was finely tuned by varying the cross-linking degree of the starting foam. Compression tests revealed, for the softest material formulation, stiffness values close to the ones possessed by natural skeletal muscles. The materials were also characterized in terms of local nanoindenting, rheometric properties and long-term stability through cyclic compressions, in a strain range reflecting the contraction extent of natural muscles. Preliminary in vitro tests revealed a preferential adhesion of C2C12 skeletal muscle cells over the softer, rougher and more porous structures. All the material formulations showed low cytotoxicity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Novel natural super-lattice materials with low thermal conductivity for thermoelectric applications: A first principles study

NASA Astrophysics Data System (ADS)

Sreeparvathy, P. C.; Kanchana, V.

2017-12-01

A systematic study which reveals the low thermal conductivity and high thermopower on a series of natural superlattice structures in the form BaXFCh (X: Cu, Ag, Ch: S, Se, Te), LaXSO (X: Cu, Ag) and SrCuTeF are presented. Low thermal conductivity is predicted by combining elastic constants and few well established models. The electronic properties reveal the highly two dimensional nature of band structure in the valence band, and this is confirmed through effective mass calculations. The huge difference in effective mass along different crystallographic directions in valence band introduces anisotropy in the transport properties for hole doping, and 'a' axis is found to be more favourable. In addition to these, the parameter A (S2σ/τT/κe /τ), which can decouple the relaxation time is also calculated, and it reveals the possibility of good thermoelectric properties in these compounds. Our results are comparable with prototype thermoelectric materials, and show better values than traditional TE materials.

Modified polyether-sulfone membrane: a mini review.

PubMed

Alenazi, Noof A; Hussein, Mahmoud A; Alamry, Khalid A; Asiri, Abdullah M

2017-01-01

Polyethersulfone has been widely used as a promising material in medical applications and waste-treatment membranes since it provides excellent mechanical and thermal properties. Hydrophobicity of polyethersulfone is considered one main disadvantage of using this material because hydrophobic surface causes biofouling effects to the membrane which is always thought to be a serious limitation to the use of polyethersulfone in membrane technology. Chemical modification to the material is a promising solution to this problem. More specifically surface modification is an excellent technique to introduce hydrophilic properties and functional groups to the polyethersulfone membrane surface. This review covers chemical modifications of the polyethersulfone and covers different methods used to enhance the hydrophilicity of polyethersulfone membrane. In particular, the addition of amino functional groups to polyethersulfone is used as a fundamental method either to introduce hydrophilic properties or introduce nanomaterials to the surface of polyethersulfone membrane. This work reviews also previous research reports explored the use of amino functionalized polyethersulfone with different nanomaterials to induce biological activity and reduce fouling effects of the fabricated membrane.

Depth of cure, flexural properties and volumetric shrinkage of low and high viscosity bulk-fill giomers and resin composites.

PubMed

Tsujimoto, Akimasa; Barkmeier, Wayne W; Takamizawa, Toshiki; Latta, Mark A; Miyazaki, Masashi

2017-03-31

The purpose of this study was to investigate the depth of cure, flexural properties and volumetric shrinkage of low and high viscosity bulk-fill giomers and resin composites. Depth of cure and flexural properties were determined according to ISO 4049, and volumetric shrinkage was measured using a dilatometer. The depths of cure of giomers were significantly lower than those of resin composites, regardless of photo polymerization times. No difference in flexural strength and modulus was found among either high or low viscosity bulk fill materials. Volumetric shrinkage of low and high viscosity bulk-fill resin composites was significantly less than low and high viscosity giomers. Depth of cure of both low and high viscosity bulk-fill materials is time dependent. Flexural strength and modulus of high viscosity or low viscosity bulk-fill giomer or resin composite materials are not different for their respective category. Resin composites exhibited less polymerization shrinkage than giomers.

Left Ventricular Diastolic and Systolic Material Property Estimation from Image Data

PubMed Central

Krishnamurthy, Adarsh; Villongco, Christopher; Beck, Amanda; Omens, Jeffrey; McCulloch, Andrew

2015-01-01

Cardiovascular simulations using patient-specific geometries can help researchers understand the mechanical behavior of the heart under different loading or disease conditions. However, to replicate the regional mechanics of the heart accurately, both the nonlinear passive and active material properties must be estimated reliably. In this paper, automated methods were used to determine passive material properties while simultaneously computing the unloaded reference geometry of the ventricles for stress analysis. Two different approaches were used to model systole. In the first, a physiologically-based active contraction model [1] coupled to a hemodynamic three-element Windkessel model of the circulation was used to simulate ventricular ejection. In the second, developed active tension was directly adjusted to match ventricular volumes at end-systole while prescribing the known end-systolic pressure. These methods were tested in four normal dogs using the data provided for the LV mechanics challenge [2]. The resulting end-diastolic and end-systolic geometry from the simulation were compared with measured image data. PMID:25729778

Sub-nanometer milling of layered materials by a focused Helium Ion Beam

NASA Astrophysics Data System (ADS)

Zhang, Hongzhou; Fox, Daniel; Zhou, Yangbo; O'Connell, Robert

2014-03-01

The modification of the structure and geometry of materials at the nanoscale can be used to tailor their properties. A controllable process which can achieve this is required for the development of next generation nano-devices. We used the highly focused beam of helium ions in a helium ion microscope (HIM) to fabricate nanostructures within various layered materials such as graphene, MoS2, TiO2 and Mn2O3. Arbitrary patterns can be defined in order to produce structures such as nanoribbons. The edge configuration of atoms in such structures plays a large role in defining their properties. High resolution transmission electron microscopy (TEM) and scanning-TEM (STEM) were used to analyse the structure of the materials after milling. The direct milling of the materials by the helium ions means this approach is suitable for a wide range of nanomaterials. Complex structures can be realized via sophisticated beam control. This also results in the ability to mill along different directions in a crystal, producing edges with different configurations.

Warm/cool-tone switchable thermochromic material for smart windows by orthogonally integrating properties of pillar[6]arene and ferrocene.

PubMed

Wang, Sai; Xu, Zuqiang; Wang, Tingting; Xiao, Tangxin; Hu, Xiao-Yu; Shen, Ying-Zhong; Wang, Leyong

2018-04-30

Functional materials play a vital role in the fabrication of smart windows, which can provide a more comfortable indoor environment for humans to enjoy a better lifestyle. Traditional materials for smart windows tend to possess only a single functionality with the purpose of regulating the input of solar energy. However, different color tones also have great influences on human emotions. Herein, a strategy for orthogonal integration of different properties is proposed, namely the thermo-responsiveness of ethylene glycol-modified pillar[6]arene (EGP6) and the redox-induced reversible color switching of ferrocene/ferrocenium groups are orthogonally integrated into one system. This gives rise to a material with cooperative and non-interfering dual functions, featuring both thermochromism and warm/cool tone-switchability. Consequently, the obtained bifunctional material for fabricating smart windows can not only regulate the input of solar energy but also can provide a more comfortable color tone to improve the feelings and emotions of people in indoor environments.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stoynov, Y.

Functionally graded materials (FGM) are extensively used in modern industry. They are composite materials with continuously varying properties in one or more special dimensions, according to the specific purpose. In view of the wide range of applications of FGM, stress analysis is important for their structural integrity and reliable service life. In this study we will consider functionally graded magneto-electro-elastic materials with one or more cracks subjected to SH waves. We assume that the material properties vary in one and the same way, described by an inhomogeneity function. The boundary value problem is reduced to a system of integro-differential equationsmore » based on the existence of fundamental solutions. Different inhomogeneity classes are used to obtain a wave equation with constant coefficients. Radon transform is applied to derive the fundamental solution in a closed form. Program code in FORTRAN 77 is developed and validated using available examples from literature. Simulations show the dependence of stress field concentration near the crack tips on the frequency of the applied time-harmonic load for different types of material inhomogeneity.« less

Decoupling the refractive index from the electrical properties of transparent conducting oxides via periodic superlattices.

PubMed

Caffrey, David; Norton, Emma; Coileáin, Cormac Ó; Smith, Christopher M; Bulfin, Brendan; Farrell, Leo; Shvets, Igor V; Fleischer, Karsten

2016-09-13

We demonstrate an alternative approach to tuning the refractive index of materials. Current methodologies for tuning the refractive index of a material often result in undesirable changes to the structural or optoelectronic properties. By artificially layering a transparent conducting oxide with a lower refractive index material the overall film retains a desirable conductivity and mobility while acting optically as an effective medium with a modified refractive index. Calculations indicate that, with our refractive index change of 0.2, a significant reduction of reflective losses could be obtained by the utilisation of these structures in optoelectronic devices. Beyond this, periodic superlattice structures present a solution to decouple physical properties where the underlying electronic interaction is governed by different length scales.

Engineering the shape and structure of materials by fractal cut.

PubMed

Cho, Yigil; Shin, Joong-Ho; Costa, Avelino; Kim, Tae Ann; Kunin, Valentin; Li, Ju; Lee, Su Yeon; Yang, Shu; Han, Heung Nam; Choi, In-Suk; Srolovitz, David J

2014-12-09

In this paper we discuss the transformation of a sheet of material into a wide range of desired shapes and patterns by introducing a set of simple cuts in a multilevel hierarchy with different motifs. Each choice of hierarchical cut motif and cut level allows the material to expand into a unique structure with a unique set of properties. We can reverse-engineer the desired expanded geometries to find the requisite cut pattern to produce it without changing the physical properties of the initial material. The concept was experimentally realized and applied to create an electrode that expands to >800% the original area with only very minor stretching of the underlying material. The generality of our approach greatly expands the design space for materials so that they can be tuned for diverse applications.

Mechanical properties of some materials used in airplane construction

NASA Technical Reports Server (NTRS)

Wolff, E B; Van Ewijk, L J G

1928-01-01

Since lightness is desirable in airplane construction, greater stresses must be tolerated than in other kinds of construction. It is therefore necessary to have a more accurate knowledge of the greatest stresses that may occur and of the actual properties of the materials used. The Aeronautic Research Laboratories took the limit of elasticity as the basis of the strength calculations. Many tests were made of different steels, woods, aluminum alloys, and fabrics.

Three-dimensional magnetophotonic crystals based on artificial opals

NASA Astrophysics Data System (ADS)

Baryshev, A. V.; Kodama, T.; Nishimura, K.; Uchida, H.; Inoue, M.

2004-06-01

We fabricated and experimentally investigated three-dimensional magnetophotonic crystals (3D MPCs) based on artificial opals. Opal samples with three-dimensional dielectric lattices were impregnated with different types of magnetic material. Magnetic and structural properties of 3D MPCs were studied by field emission scanning electron microscopy, x-ray diffraction analysis, and vibrating sample magnetometer. We have shown that magnetic materials synthesized in voids of opal lattices and the composites obtained have typical magnetic properties.

Optimized Power Generation and Distribution Unit for Mobile Applications

DTIC Science & Technology

2006-09-01

reference commands to the overall system. This would be consistent with exoskeleton usage . Power Generation (prime mover) Power Distribution...technologies i.e. technologies that as of yet have not been used in the same field. • Produce list(s) in order of ranking for different properties ...developments have come through material science and bearing technology – it is the material properties of a flywheel that determine the maximum energy that can

Relationship between Surface Properties and In Vitro Drug Release from Compressed Matrix Containing Polymeric Materials with Different Hydrophobicity Degrees

PubMed Central

Yarce, Cristhian J.; Echeverri, Juan D.; Palacio, Mario A.; Rivera, Carlos A.; Salamanca, Constain H.

2017-01-01

This work is the continuation of a study focused on establishing relations between surface thermodynamic properties and in vitro release mechanisms using a model drug (ampicillin trihydrate), besides analyzing the granulometric properties of new polymeric materials and thus establishing the potential to be used in the pharmaceutical field as modified delivery excipients. To do this, we used copolymeric materials derived from maleic anhydride with decreasing polarity corresponding to poly(isobutylene-alt-maleic acid) (hydrophilic), sodium salt of poly(maleic acid-alt-octadecene) (amphiphilic), poly(maleic anhydride-alt-octadecene) (hydrophobic) and the reference polymer hydroxyl-propyl-methyl-cellulose (HPMC). Each material alone and in blends underwent spectroscopic characterization by FTIR, thermal characterization by DSC and granulometric characterization using flow and compaction tests. Each tablet was prepared at different polymer ratios of 0%, 10%, 20%, 30% and 40%, and the surface properties were determined, including the roughness by micro-visualization, contact angle and water absorption rate by the sessile drop method and obtaining Wadh and surface free energy (SFE) using the semi-empirical models of Young–Dupré and  Owens-Wendt-Rabel-Käelbe (OWRK), respectively. Dissolution profiles were determined simulating physiological conditions in vitro, where the kinetic models of order-zero, order-one, Higuchi and Korsmeyer–Peppas were evaluated. The results showed a strong relationship between the proportion and nature of the polymer to the surface thermodynamic properties and kinetic release mechanism. PMID:28125020

Flat tensile specimen design for advanced composites

NASA Technical Reports Server (NTRS)

Worthem, Dennis W.

1990-01-01

Finite element analyses of flat, reduced gage section tensile specimens with various transition region contours were performed. Within dimensional constraints, such as maximum length, tab region width, gage width, gage length, and minimum tab length, a transition contour radius of 41.9 cm produced the lowest stress values in the specimen transition region. The stresses in the transition region were not sensitive to specimen material properties. The stresses in the tab region were sensitive to specimen composite and/or tab material properties. An evaluation of stresses with different specimen composite and tab material combinations must account for material nonlinearity of both the tab and the specimen composite. Material nonlinearity can either relieve stresses in the composite under the tab or elevate them to cause failure under the tab.

Effect of Processing Variables on the Microstructure and Mechanical Properties of Microporous Carbon Materials

NASA Technical Reports Server (NTRS)

Singh, M.; Dacek, R. F.

1996-01-01

Microporous carbon materials with different pore and strut sizes have been fabricated by the pyrolysis of furfuryl alcohol resin, triethylene glycol, and p-toluene sulfonic acid mixtures. The resulting materials were characterized by scanning electron microscopy and density measurements. The room temperature flexural strength and modulus of these materials decreases with increasing amount of acid curing agent.

Fluorinated arene, imide and unsaturated pyrrolidinone based donor acceptor conjugated polymers: Synthesis, structure-property and device studies

NASA Astrophysics Data System (ADS)

Liyanage, Arawwawala Don Thilanga

After the discovery of doped polyacetylene, organic semiconductor materials are widely studied as high impending active components in consumer electronics. They have received substantial consideration due to their potential for structural tailoring, low cost, large area and mechanically flexible alternatives to common inorganic semiconductors. To acquire maximum use of these materials, it is essential to get a strong idea about their chemical and physical nature. Material chemist has an enormous role to play in this novel area, including development of efficient synthetic methodologies and control the molecular self-assembly and (opto)-electronic properties. The body of this thesis mainly focuses on the substituent effects: how different substituents affect the (opto)-electronic properties of the donor-acceptor (D-A) conjugated polymers. The main priority goes to understand, how different alkyl substituent effect to the polymer solubility, crystallinity, thermal properties (e.g.: glass transition temperature) and morphological order. Three classes of D-A systems were extensively studied in this work. The second chapter mainly focuses on the synthesis and structure-property study of fluorinated arene (TFB) base polymers. Here we used commercially available 1,4-dibromo-2,3,5,6-tetrafluorobenzene (TFB) as the acceptor material and prepare several polymers using 3,3'-dialkyl(3,3'-R2T2) or 3,3'-dialkoxy bithiophene (3,3'-RO2T2) units as electron donors. A detail study was done using 3,3'-bithiophene donor units incorporating branched alkoxy-functionalities by systematic variation of branching position and chain length. The study allowed disentangling the branching effects on (i) aggregation tendency, intermolecular arrangement, (iii) solid state optical energy gaps, and (iv) electronic properties in an overall consistent picture, which might guide future polymer synthesis towards optimized materials for opto-electronic applications. The third chapter mainly focused on the structure-property study of imide functionalized D-A polymers. Here we used thiophene-imide (TPD) as the acceptor moiety and prepare several D-A polymers by varying the donor units. When selecting the donor units, more priority goes to the fused ring systems. One main reason to use imide functionality is due to the, open position of the imide nitrogen, which provides an attaching position to alkyl substituent. Through this we can easily manipulate solubility and solid state packing arrangement. Also these imide acceptors have low-lying LUMOs due to their electron deficient nature and this will allow tuning the optical energy gap by careful choice of donor materials with different electron donating ability. The fourth chapter mainly contribute to the synthesis and structure property study of a completely novel electron acceptor moiety consist of a unsaturated pyrrolidinone unit known as Pechmann dye (PD) core. Pechmann dyes are closely related to the Indigo family. This can refer as 3-butenolide dimer connected via an alkene bridge, containing a benzene ring at the 5 and 5' positions of the lactone rings. We have prepared several D-A polymers using this PD system with benzodithiophene (BDT) as the donor unit. Different to common D-A polymers the HOMO and LUMO of the PD acceptor moiety are energetically located within the gap of the BDT, so that the electronic and optical properties (HOMO-LUMO transition) are dictated by the PD properties. The promising electronic properties, band gaps, high absorption coefficients and broad absorption suggest this new D-A polymers as an interesting donor material for organic solar cell (OSC) applications. KEY WORDS: Organic semiconductor materials, Self assembly, (opto)-electronic properties, Donor-Acceptor conjugated polymers, Fluorinated arene, 3,3'-bithiophene donors, Thiophene-imide (TPD), Pechmann dye, benzodithiophene, organic solar cell.

Synthesis and physical characterization of γ-Fe2O3 and (α+γ)-Fe2O3 nanoparticles

NASA Astrophysics Data System (ADS)

Bhavani, P.; Reddy, N. Ramamanohar; Reddy, I. Venkata Subba

2017-01-01

Magnetic nanoparticles were synthesized at different hydrothermal temperatures (HT; 100, 130, 160 and 190 °C) by using a facile hydrothermal route combined with a subsequent calcination process. The calcined materials were analyzed for phase, microstructure, and magnetic and dielectric properties through different characterization techniques. The structural analyses revealed that the material prepared at a HT of 100 °C and sequentially calcined at 300 °C for 3 h showed a high degree of the maghemite structure. On the other hand calcined materials showed a small additional peak belonging to the hematite structure. FESEM micrographs of the materials calcined at HT, of 100 °C and 190 °C showed spherical-like nanoparticles with diameters in range 30 - 54 nm. Materials prepared at a HT of 160 °C followed by calcination at 300 °C for 3 h exhibited the highest saturation magnetization, Ms = 67 emu/g, with a lower coercivity; all materials were in a single domain state. A high dielectric constant (105.54) was observed for the calcined material that had been prepared at a HT of 130 °C. The dielectric properties of synthesized materials showed an almost frequency-independent behavior.

Thermophysical Properties of Mars' North Polar Layered Deposits and Related Materials from Mars Odyssey THEMIS

NASA Technical Reports Server (NTRS)

Vasavada, A. R.; Richardson, M. I.; Byrne, S.; Ivanov, A. B.; Christensen, P. R.

2003-01-01

The presence of a thick sequence of horizontal layers of ice-rich material at Mars north pole, dissected by troughs and eroding at its margins, is undoubtedly telling us something about the evolution of Mars climate [1,2] we just don t know what yet. The North Polar Layered Deposits (NPLD) most likely formed as astronomically driven climate variations led to the deposition of conformable, areally extensive layers of ice and dust over the polar region. More recently, the balance seems to have fundamentally shifted to net erosion, as evidenced by the many troughs within the NPLD and the steep, arcuate scarps present near its margins, both of which expose layering. We defined a number of Regions of Interest ROI) for THEMIS to target as part of the Mars Odyssey Participating Scientist program. We use these THEMIS data in order to understand the morphology and color/thermal properties of the NPLD and related materials over relevant (i.e., m to km) spatial scales. We have assembled color mosaics of our ROIs in order to map the distribution of ices, the different layered units, dark material, and underlying basement. The color information from THEMIS is crucial for distinguishing these different units which are less distinct on Mars Orbiter Camera images. We wish to understand the nature of the marginal scarps and their relationship to the dark material. Our next, more ambitious goal is to derive the thermophysical properties of the different geologic materials using THEMIS and Mars Global Surveyor Thermal Emission Spectrometer TES) data.

Method and apparatus for vibrating a substrate during material formation

DOEpatents

Bailey, Jeffrey A [Richland, WA; Roger, Johnson N [Richland, WA; John, Munley T [Benton City, WA; Walter, Park R [Benton City, WA

2008-10-21

A method and apparatus for affecting the properties of a material include vibrating the material during its formation (i.e., "surface sifting"). The method includes the steps of providing a material formation device and applying a plurality of vibrations to the material during formation, which vibrations are oscillations having dissimilar, non-harmonic frequencies and at least two different directions. The apparatus includes a plurality of vibration sources that impart vibrations to the material.

Polarized Light Microscopy

NASA Technical Reports Server (NTRS)

Frandsen, Athela F.

2016-01-01

Polarized light microscopy (PLM) is a technique which employs the use of polarizing filters to obtain substantial optical property information about the material which is being observed. This information can be combined with other microscopy techniques to confirm or elucidate the identity of an unknown material, determine whether a particular contaminant is present (as with asbestos analysis), or to provide important information that can be used to refine a manufacturing or chemical process. PLM was the major microscopy technique in use for identification of materials for nearly a century since its introduction in 1834 by William Fox Talbot, as other techniques such as SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Infrared spectroscopy), XPD (X-ray Powder Diffraction), and TEM (Transmission Electron Microscopy) had not yet been developed. Today, it is still the only technique approved by the Environmental Protection Agency (EPA) for asbestos analysis, and is often the technique first applied for identification of unknown materials. PLM uses different configurations in order to determine different material properties. With each configuration additional clues can be gathered, leading to a conclusion of material identity. With no polarizing filter, the microscope can be used just as a stereo optical microscope, and view qualities such as morphology, size, and number of phases. With a single polarizing filter (single polars), additional properties can be established, such as pleochroism, individual refractive indices, and dispersion staining. With two polarizing filters (crossed polars), even more can be deduced: isotropy vs. anisotropy, extinction angle, birefringence/degree of birefringence, sign of elongation, and anomalous polarization colors, among others. With the use of PLM many of these properties can be determined in a matter of seconds, even for those who are not highly trained. McCrone, a leader in the field of polarized light microscopy, often advised, If you cant determine a specific optical property of a particle after two minutes, move onto another configuration. Since optical properties can be seen so very quickly and easily under polarized light, it is only necessary to spend a maximum of two minutes on a technique to determine a particular property, though often only a few seconds are required.

Wood properties affecting finish service life

Treesearch

R. Sam Williams; Charles Jourdain; George I. Daisey; Robert W. Springate

2000-01-01

Wood is a biological material that has widely different properties depending on species, geographic area where the tree grew, the growth conditions, size of the tree at harvest, sawing, and other manufacturing processes. Some of the more important wood properties as they relate to wood finishing are discussed, e.g., growth rate, density, knots, extractives, juvenile...

Improvement of the mechanical, tribological and antibacterial properties of glass ionomer cements by fluorinated graphene.

PubMed

Sun, Li; Yan, Zhuanjun; Duan, Youxin; Zhang, Junyan; Liu, Bin

2018-06-01

The aim of this study was to improve the mechanical properties, wear resistance and antibacterial properties of conventional glass ionomer cements (GICs) by fluorinated graphene (FG), under the premise of not influencing their solubility and fluoride ion releasing property. FG with bright white color was prepared using graphene oxide by a hydrothermal reaction. Experimental modified GICs was prepared by adding FG to the traditional GICs powder with four different weight ratios (0.5wt%, 1wt%, 2wt% and 4wt%) using mechanical blending. Compressive and flexural strength of each experimental and control group materials were investigated using a universal testing machine. The Vickers microhardness of all the specimens was measured by a Vicker microhardness tester. For tribological properties of the composites, specimens of each group were investigated by high-speed reciprocating friction tester. Fluoride ion releasing was measured by fluoride ion selective electrode methods. The antibacterial effect of GICs/FG composites on selected bacteria (Staphylococci aureus and Streptococcus mutans) was tested with pellicle sticking method. The prepared GICs/FG composites with white color were successfully fabricated. Increase of Vickers microhardness and compressive strength and decrease of friction coefficient of the GICs/FG composites were achieved compared to unreinforced materials. The colony count against S. aureus and S. mutans decreased with the increase of the content of FG. And the antibacterial rate of S. mutans can be up to 85.27% when the FG content was 4wt%. Additionally, fluoride ion releasing property and solubility did not show significant differences between unreinforced and FG reinforced GICs. Adding FG to traditional GICs could not only improve mechanical and tribological properties of the composites, but also improve their antibacterial properties. In addition, the GICs/FG composites had no negative effect on the color, solubility and fluoride ion releasing properties, which will open up new roads for the application of dental materials. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

Theoretical studies on leaky-SAW properties influenced by layers on anisotropic piezoelectric crystals.

PubMed

Wallner, P; Ruile, W; Weigel, R

2000-01-01

Theoretical studies on the behavior of leaky-SAW (LSAW) properties in layered structures were performed. For these calculations rotYX LiTaO (3) and rotYX LiNbO(3) LSAW crystal cuts were used, assuming different layer materials. For LSAWs both the velocity and the inherent loss due to bulk wave emission into the substrate are strongly influenced by distinct layer parameters. As a result, these layer properties like elastic constants or thickness have shown a strong influence on the crystal cut angle of minimum LSAW loss. Moreover, for soft and stiff layer materials, a different shift of the LSAW loss minimum can occur. Therefore, using double-layer structures, the shift of the LSAW loss minimum can be influenced by appropriate chosen layers and ratios.

Evaluation criteria for spectral design of camouflage

NASA Astrophysics Data System (ADS)

Škerlind, Christina; Fagerström, Jan; Hallberg, Tomas; Kariis, Hans

2015-10-01

In development of visual (VIS) and infrared (IR) camouflage for signature management, the aim is the design of surface properties of an object to spectrally match or adapt to a background and thereby minimizing the contrast perceived by a threatening sensor. The so called 'ladder model" relates the requirements for task measure of effectiveness with surface structure properties through the steps signature effectiveness and object signature. It is intended to link materials properties via platform signature to military utility and vice versa. Spectral design of a surface intends to give it a desired wavelength dependent optical response to fit a specific application of interest. Six evaluation criteria were stated, with the aim to aid the process to put requirement on camouflage and for evaluation. The six criteria correspond to properties such as reflectance, gloss, emissivity, and degree of polarization as well as dynamic properties, and broadband or multispectral properties. These criteria have previously been exemplified on different kinds of materials and investigated separately. Anderson and Åkerlind further point out that the six criteria rarely were considered or described all together in one and same publication previously. The specific level of requirement of the different properties must be specified individually for each specific situation and environment to minimize the contrast between target and a background. The criteria or properties are not totally independent of one another. How they are correlated is part of the theme of this paper. However, prioritization has been made due to the limit of space. Therefore all of the interconnections between the six criteria will not be considered in the work of this report. The ladder step previous to digging into the different material composition possibilities and choice of suitable materials and structures (not covered here), includes the object signature and decision of what the spectral response should be, when intended for a specific environment. The chosen spectral response should give a low detection probability (DP). How detection probability connects to image analysis tools and implementation of the six criteria is part of this work.

Optimisation of powders for pulmonary delivery using supercritical fluid technology.

PubMed

Rehman, Mahboob; Shekunov, Boris Y; York, Peter; Lechuga-Ballesteros, David; Miller, Danforth P; Tan, Trixie; Colthorpe, Paul

2004-05-01

Supercritical fluid technology exploited in this work afforded single-step production of respirable particles of terbutaline sulphate (TBS). Different crystal forms of TBS were produced consistently, including two polymorphs, a stoichiometric monohydrate and amorphous material as well as particles with different degrees of crystallinity, size, and morphology. Different solid-state and surface characterisation techniques were applied in conjunction with measurements of powder flow properties using AeroFlow device and aerosol performance by Andersen Cascade Impactor tests. Improved fine particle fraction (FPF) was demonstrated for some powders produced by the SCF process when compared to the micronised material. Such enhanced flow properties and dispersion correlated well with the reduced surface energy parameters demonstrated by these powders. It is shown that semi-crystalline particles exhibited lower specific surface energy leading to a better performance in the powder flow and aerosol tests than crystalline materials. This difference of the surface and bulk crystal structure for selected powder batches is explained by the mechanism of precipitation in SCF which can lead to surface conditioning of particles produced.

Nitride-Based Materials for Flexible MEMS Tactile and Flow Sensors in Robotics

PubMed Central

Abels, Claudio; Mastronardi, Vincenzo Mariano; Guido, Francesco; Dattoma, Tommaso; Qualtieri, Antonio; Megill, William M.; De Vittorio, Massimo; Rizzi, Francesco

2017-01-01

The response to different force load ranges and actuation at low energies is of considerable interest for applications of compliant and flexible devices undergoing large deformations. We present a review of technological platforms based on nitride materials (aluminum nitride and silicon nitride) for the microfabrication of a class of flexible micro-electro-mechanical systems. The approach exploits the material stress differences among the constituent layers of nitride-based (AlN/Mo, SixNy/Si and AlN/polyimide) mechanical elements in order to create microstructures, such as upwardly-bent cantilever beams and bowed circular membranes. Piezoresistive properties of nichrome strain gauges and direct piezoelectric properties of aluminum nitride can be exploited for mechanical strain/stress detection. Applications in flow and tactile sensing for robotics are described. PMID:28489040

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.

Simulation based estimation of dynamic mechanical properties for viscoelastic materials used for vocal fold models

NASA Astrophysics Data System (ADS)

Rupitsch, Stefan J.; Ilg, Jürgen; Sutor, Alexander; Lerch, Reinhard; Döllinger, Michael

2011-08-01

In order to obtain a deeper understanding of the human phonation process and the mechanisms generating sound, realistic setups are built up containing artificial vocal folds. Usually, these vocal folds consist of viscoelastic materials (e.g., polyurethane mixtures). Reliable simulation based studies on the setups require the mechanical properties of the utilized viscoelastic materials. The aim of this work is the identification of mechanical material parameters (Young's modulus, Poisson's ratio, and loss factor) for those materials. Therefore, we suggest a low-cost measurement setup, the so-called vibration transmission analyzer (VTA) enabling to analyze the transfer behavior of viscoelastic materials for propagating mechanical waves. With the aid of a mathematical Inverse Method, the material parameters are adjusted in a convenient way so that the simulation results coincide with the measurement results for the transfer behavior. Contrary to other works, we determine frequency dependent functions for the mechanical properties characterizing the viscoelastic material in the frequency range of human speech (100-250 Hz). The results for three different materials clearly show that the Poisson's ratio is close to 0.5 and that the Young's modulus increases with higher frequencies. For a frequency of 400 Hz, the Young's modulus of the investigated viscoelastic materials is approximately 80% higher than for the static case (0 Hz). We verify the identified mechanical properties with experiments on fabricated vocal fold models. Thereby, only small deviations between measurements and simulations occur.

Bioinspired Functional Surfaces for Technological Applications

NASA Astrophysics Data System (ADS)

Sharma, Vipul; Kumar, Suneel; Reddy, Kumbam Lingeshwar; Bahuguna, Ashish; Krishnan, Venkata

2016-08-01

Biological matters have been in continuous encounter with extreme environmental conditions leading to their evolution over millions of years. The fittest have survived through continuous evolution, an ongoing process. Biological surfaces are the important active interfaces between biological matters and the environment, and have been evolving over time to a higher state of intelligent functionality. Bioinspired surfaces with special functionalities have grabbed attention in materials research in the recent times. The microstructures and mechanisms behind these functional biological surfaces with interesting properties have inspired scientists to create artificial materials and surfaces which possess the properties equivalent to their counterparts. In this review, we have described the interplay between unique multiscale (micro- and nano-scale) structures of biological surfaces with intrinsic material properties which have inspired researchers to achieve the desired wettability and functionalities. Inspired by naturally occurring surfaces, researchers have designed and fabricated novel interfacial materials with versatile functionalities and wettability, such as superantiwetting surfaces (superhydrophobic and superoleophobic), omniphobic, switching wettability and water collecting surfaces. These strategies collectively enable functional surfaces to be utilized in different applications such as fog harvesting, surface-enhanced Raman spectroscopy (SERS), catalysis, sensing and biological applications. This paper delivers a critical review of such inspiring biological surfaces and artificial bioinspired surfaces utilized in different applications, where material science and engineering have merged by taking inspiration from the natural systems.

Graphene-based smart materials

NASA Astrophysics Data System (ADS)

Yu, Xiaowen; Cheng, Huhu; Zhang, Miao; Zhao, Yang; Qu, Liangti; Shi, Gaoquan

2017-09-01

The high specific surface area and the excellent mechanical, electrical, optical and thermal properties of graphene make it an attractive component for high-performance stimuli-responsive or 'smart' materials. Complementary to these inherent properties, functionalization or hybridization can substantially improve the performance of these materials. Typical graphene-based smart materials include mechanically exfoliated perfect graphene, chemical vapour deposited high-quality graphene, chemically modified graphene (for example, graphene oxide and reduced graphene oxide) and their macroscopic assemblies or composites. These materials are sensitive to a range of stimuli, including gas molecules or biomolecules, pH value, mechanical strain, electrical field, and thermal or optical excitation. In this Review, we outline different graphene-based smart materials and their potential applications in actuators, chemical or strain sensors, self-healing materials, photothermal therapy and controlled drug delivery. We also introduce the working mechanisms of graphene-based smart materials and discuss the challenges facing the realization of their practical applications.

Tuning acoustic and mechanical properties of materials for ultrasound phantoms and smart substrates for cell cultures.

PubMed

Cafarelli, A; Verbeni, A; Poliziani, A; Dario, P; Menciassi, A; Ricotti, L

2017-02-01

Materials with tailored acoustic properties are of great interest for both the development of tissue-mimicking phantoms for ultrasound tests and smart scaffolds for ultrasound mediated tissue engineering and regenerative medicine. In this study, we assessed the acoustic properties (speed of sound, acoustic impedance and attenuation coefficient) of three different materials (agarose, polyacrylamide and polydimethylsiloxane) at different concentrations or cross-linking levels and doped with different concentrations of barium titanate ceramic nanoparticles. The selected materials, besides different mechanical features (stiffness from few kPa to 1.6MPa), showed a wide range of acoustic properties (speed of sound from 1022 to 1555m/s, acoustic impedance from 1.02 to 1.67MRayl and attenuation coefficient from 0.2 to 36.5dB/cm), corresponding to ranges in which natural soft tissues can fall. We demonstrated that this knowledge can be used to build tissue-mimicking phantoms for ultrasound-based medical procedures and that the mentioned measurements enable to stimulate cells with a highly controlled ultrasound dose, taking into account the attenuation due to the cell-supporting scaffold. Finally, we were able to correlate for the first time the bioeffect on human fibroblasts, triggered by piezoelectric barium titanate nanoparticles activated by low-intensity pulsed ultrasound, with a precise ultrasound dose delivered. These results may open new avenues for the development of both tissue-mimicking materials for ultrasound phantoms and smart triggerable scaffolds for tissue engineering and regenerative medicine. This study reports for the first time the results of a systematic acoustic characterization of agarose, polyacrylamide and polydimethylsiloxane at different concentrations and cross-linking extents and doped with different concentrations of barium titanate nanoparticles. These results can be used to build tissue-mimicking phantoms, useful for many ultrasound-based medical procedures, and to fabricate smart materials for stimulating cells with a highly controlled ultrasound dose. Thanks to this knowledge, we correlated for the first time a bioeffect (the proliferation increase) on human fibroblasts, triggered by piezoelectric nanoparticles, with a precise US dose delivered. These results may open new avenues for the development of both tissue-mimicking phantoms and smart triggerable scaffolds for tissue engineering and regenerative medicine. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Self-sensing and thermal energy experimental characterization of multifunctional cement-matrix composites with carbon nano-inclusions

NASA Astrophysics Data System (ADS)

D'Alessandro, A.; Pisello, A. L.; Sambuco, Sara; Ubertini, F.; Asdrubali, F.; Materazzi, A. L.; Cotana, F.

2016-04-01

The recent progress of Nanotechnology allowed the development of new smart materials in several fields of engineering. In particular, innovative construction materials with multifunctional enhanced properties can be produced. The paper presents an experimental characterization on cement-matrix pastes doped with Carbon Nanotubes, Carbon Nano-fibers, Carbon Black and Graphene Nano-platelets. Both electro-mechanical and thermo-physical investigations have been carried out. The conductive nano-inclusions provide the cementitious matrix with piezo-resistive properties allowing the detection of external strain and stress changes. Thereby, traditional building materials, such as concrete and cementitious materials in general, would be capable of self-monitoring the state of deformation they are subject to, giving rise to diffuse sensing systems of structural integrity. Besides supplying self-sensing abilities, carbon nano-fillers may change mechanical, physical and thermal properties of cementitious composites. The experimental tests of the research have been mainly concentrated on the thermal conductivity and the optical properties of the different nano-modified materials, in order to make a critical comparison between them. The aim of the work is the characterization of an innovative multifunctional composite capable of combining self-monitoring properties with proper mechanical and thermal-energy efficiency characteristics. The potential applications of these nano-modified materials cover a wide range of possibilities, such as structural elements, floors, geothermal piles, radiant systems and more.

Machine learning for the structure-energy-property landscapes of molecular crystals.

PubMed

Musil, Félix; De, Sandip; Yang, Jack; Campbell, Joshua E; Day, Graeme M; Ceriotti, Michele

2018-02-07

Molecular crystals play an important role in several fields of science and technology. They frequently crystallize in different polymorphs with substantially different physical properties. To help guide the synthesis of candidate materials, atomic-scale modelling can be used to enumerate the stable polymorphs and to predict their properties, as well as to propose heuristic rules to rationalize the correlations between crystal structure and materials properties. Here we show how a recently-developed machine-learning (ML) framework can be used to achieve inexpensive and accurate predictions of the stability and properties of polymorphs, and a data-driven classification that is less biased and more flexible than typical heuristic rules. We discuss, as examples, the lattice energy and property landscapes of pentacene and two azapentacene isomers that are of interest as organic semiconductor materials. We show that we can estimate force field or DFT lattice energies with sub-kJ mol -1 accuracy, using only a few hundred reference configurations, and reduce by a factor of ten the computational effort needed to predict charge mobility in the crystal structures. The automatic structural classification of the polymorphs reveals a more detailed picture of molecular packing than that provided by conventional heuristics, and helps disentangle the role of hydrogen bonded and π-stacking interactions in determining molecular self-assembly. This observation demonstrates that ML is not just a black-box scheme to interpolate between reference calculations, but can also be used as a tool to gain intuitive insights into structure-property relations in molecular crystal engineering.

Damage assessment of composite plate structures with material and measurement uncertainty

NASA Astrophysics Data System (ADS)

Chandrashekhar, M.; Ganguli, Ranjan

2016-06-01

Composite materials are very useful in structural engineering particularly in weight sensitive applications. Two different test models of the same structure made from composite materials can display very different dynamic behavior due to large uncertainties associated with composite material properties. Also, composite structures can suffer from pre-existing imperfections like delaminations, voids or cracks during fabrication. In this paper, we show that modeling and material uncertainties in composite structures can cause considerable problem in damage assessment. A recently developed C0 shear deformable locking free refined composite plate element is employed in the numerical simulations to alleviate modeling uncertainty. A qualitative estimate of the impact of modeling uncertainty on the damage detection problem is made. A robust Fuzzy Logic System (FLS) with sliding window defuzzifier is used for delamination damage detection in composite plate type structures. The FLS is designed using variations in modal frequencies due to randomness in material properties. Probabilistic analysis is performed using Monte Carlo Simulation (MCS) on a composite plate finite element model. It is demonstrated that the FLS shows excellent robustness in delamination detection at very high levels of randomness in input data.

Mechanic and surface properties of central-venous port catheters after removal: A comparison of polyurethane and silicon rubber materials.

PubMed

Braun, Ulrike; Lorenz, Edelgard; Weimann, Christiane; Sturm, Heinz; Karimov, Ilham; Ettl, Johannes; Meier, Reinhard; Wohlgemuth, Walter A; Berger, Hermann; Wildgruber, Moritz

2016-12-01

Central venous port devices made of two different polymeric materials, thermoplastic polyurethane (TPU) and silicone rubber (SiR), were compared due their material properties. Both naïve catheters as well as catheters after removal from patients were investigated. In lab experiments the influence of various chemo-therapeutic solutions on material properties was investigated, whereas the samples after removal were compared according to the implanted time in patient. The macroscopic, mechanical performance was assessed with dynamic, specially adapted tests for elasticity. The degradation status of the materials was determined with common tools of polymer characterisation, such as infrared spectroscopy, molecular weight measurements and various methods of thermal analysis. The surface morphology was analysed using scanning electron microscopy. A correlation between material properties and clinical performance was proposed. The surface morphology and chemical composition of the polyurethane catheter materials can potentially result in increased susceptibility of the catheter to bloodstream infections and thrombotic complications. The higher mechanic failure, especially with increasing implantation time of the silicone catheters is related to the lower mechanical performance compared to the polyurethane material as well as loss of barium sulphate filler particles near the surface of the catheter. This results in preformed microscopic notches, which act as predetermined sites of fracture. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mechanical characterization of commercial biodegradable plastic films

NASA Astrophysics Data System (ADS)

Vanstrom, Joseph R.

Polylactic acid (PLA) is a biodegradable plastic that is relatively new compared to other plastics in use throughout industry. The material is produced by the polymerization of lactic acid which is produced by the fermentation of starches derived from renewable feedstocks such as corn. Polylactic acid can be manufactured to fit a wide variety of applications. This study details the mechanical and morphological properties of selected commercially available PLA film products. Testing was conducted at Iowa State University and in conjunction with the United States Department of Agriculture (USDA) BioPreferred ProgramRTM. Results acquired by Iowa State were compared to a similar study performed by the Cortec Corporation in 2006. The PLA films tested at Iowa State were acquired in 2009 and 2010. In addition to these two studies at ISU, the films that were acquired in 2009 were aged for a year in a controlled environment and then re-tested to determine effects of time (ageing) on the mechanical properties. All films displayed anisotropic properties which were confirmed by inspection of the films with polarized light. The mechanical testing of the films followed American Society for Testing and Materials (ASTM) standards. Mechanical characteristics included: tensile strength (ASTM D882), elongation of material at failure (ASTM D882), impact resistance (ASTM D1922), and tear resistance (ASTM D4272). The observed values amongst all the films ranged as followed: tensile strength 33.65--8.54 MPa; elongation at failure 1,665.1%--47.2%; tear resistance 3.61--0.46 N; and puncture resistance 2.22--0.28 J. There were significant differences between the observed data for a number of films and the reported data published by the Cortec Corp. In addition, there were significant differences between the newly acquired material from 2009 and 2010, as well as the newly acquired materials in 2009 and the aged 2009 materials, suggesting that ageing and manufacturing date had an effect on the mechanical properties. The morphological properties were tested using Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). The material properties examined were: glass transition temperature (Tg), degree of crystallinity (Wc), and material composition in terms of inorganic content. Results from DSC testing revealed that the glass transition temperatures ranged from 43.2--52.2 °C, the degree of crystallintiy ranged from 4.1--13.8%, and material composition of the films ranged from 89.9--100% organic materials. The morphological examination of the polymers also indicated that the mechanical properties of the films may have been altered by the manufacturing and processing of the film material or by the addition of filler or plasticizers.

Exceeding the filling fraction limit: An approach to enhancement of thermoelectric properties of filled - Co4Sb12 skutterudite

NASA Astrophysics Data System (ADS)

Graff, Jennifer Whitney

Currently the world energy usage has nearly tripled since 1950 and is projected to grow at a rate of 1.5% per year and predicted to at least double from the beginning of the millennium to 2050. The United States alone is currently consuming more energy than it can produce (≈ 97 Quadrillion BTU's consumed in 2011).(1) Presently, fossil fuels make up over 85% of our energy landscape, including both the stationary grid (like coal and nuclear power plants) and the mobile grid (automobiles using gas and oil). This presents a major demand for developing methods of saving, storing, and renewing energy. Answers to these existing energy demands must come from a variety of renewable sources including: solar, wind, biomass, geothermal and others. But currently, most renewable sources are only a small part of the big energy picture. One approach to this exponentially growing problem, lies within high efficiency (15%-20%) thermoelectric (TE) materials which address small, yet very important and specific, parts of a bigger problem. Specifically, Co4Sb12-based skutterudites, an increasingly favorable thermoelectric material for mid to high temperature applications (currently used in General Motors TE Generator devices). These materials have the ability to be 'tuned' or controlled thermally and electrically through doping and filling mechanisms, as you will see in this dissertation. However, one of the major drawbacks of TE materials is the difficulty in optimizing both electrical and thermal properties simultaneously. Typically, different control parameters are used in order to enhance the electrical and thermal properties individually. It is very rare to observe optimization of both in a TE material via one control parameter. However, the work presented herein successfully augments all TE properties, with one control variable, by using an approach that can be applied to all doped skutterudites and clathrate materials. Skutterudites are novel materials in that they are a binary system with a crystalline framework and a narrow band gap, so they naturally possess relatively good electrical properties. This dissertation seeks to answer the question: Can we continue to improve the efficiency of one of the leading TE materials in power generation applications -- skutterudites? In trying to answer this question we discovered a material that had never been tested for its TE properties and found that it exhibits behavior not typically observed in these materials as well as showing improvements in all TE properties (electrical and thermal) via one control parameter. We also successfully improved the TE efficiencies of several different filled skutterudites by a single approach which can be applied to other skutterudite and cage-like materials.

From Commodity Polymers to Functional Polymers

PubMed Central

Xiang, Tao; Wang, Ling-Ren; Ma, Lang; Han, Zhi-Yuan; Wang, Rui; Cheng, Chong; Xia, Yi; Qin, Hui; Zhao, Chang-Sheng

2014-01-01

Functional polymers bear specified chemical groups, and have specified physical, chemical, biological, pharmacological, or other uses. To adjust the properties while keeping material usage low, a method for direct synthesis of functional polymers is indispensable. Here we show that various functional polymers can be synthesized by in situ cross-linked polymerization/copolymerization. We demonstrate that the polymers synthesized by the facile method using different functional monomers own outstanding pH-sensitivity and pH-reversibility, antifouling property, antibacterial, and anticoagulant property. Our study opens a route for the functionalization of commodity polymers, which lead to important advances in polymeric materials applications. PMID:24710333

Multi-sensor electrometer

NASA Technical Reports Server (NTRS)

Gompf, Raymond (Inventor); Buehler, Martin C. (Inventor)

2003-01-01

An array of triboelectric sensors is used for testing the electrostatic properties of a remote environment. The sensors may be mounted in the heel of a robot arm scoop. To determine the triboelectric properties of a planet surface, the robot arm scoop may be rubbed on the soil of the planet and the triboelectrically developed charge measured. By having an array of sensors, different insulating materials may be measured simultaneously. The insulating materials may be selected so their triboelectric properties cover a desired range. By mounting the sensor on a robot arm scoop, the measurements can be obtained during an unmanned mission.

Potential space applications of nanomaterials and standartization issues

NASA Astrophysics Data System (ADS)

Voronina, Ekaterina; Novikov, Lev

Nanomaterials surpass traditional materials for space applications in many aspects due to their unique properties associated with nanoscale size of their constituents. This superiority in mechanical, thermal, electrical and optical properties will evidently inspire a wide range of applications in the next generation spacecraft intended for the long-term (~15-20 years) operation in near-Earth orbits and the automatic and manned interplanetary missions as well as in the construction of inhabited bases on the Moon. Nanocomposites with nanoclays, carbon nanotubes and various nanoparticles as fillers are one of the most promising materials for space applications. They may be used as light-weighted and strong structural materials as well as functional and smart materials of general and specific applications, e.g. thermal stabilization, radiation shielding, electrostatic charge mitigation, protection of atomic oxygen influence and space debris impact, etc. Currently, ISO activity on developing standards concerning different issues of nanomaterials manufacturing and applications is high enough. In this presentation, a brief review of existing standards and standards under development in this field is given. Most such standards are related to nanoparticles and nanotube production and characterization, thus the next important step in this activity is the creation of standards on nanomaterial properties and their behavior in different environmental conditions, including extreme environments. The near-Earth’s space is described as an extreme environment for materials due to high vacuum, space radiation, hot and cold plasma, micrometeoroids and space debris, temperature differences, etc. Existing experimental and theoretical data demonstrate that nanomaterials response to various space environment effects may differ substantially from the one of conventional bulk spacecraft materials. Therefore, it is necessary to determine the space environment components, critical for nanomaterials, and to develop novel methods of the mathematical and experimental simulation of the space environment impact on nanomaterials. Computer simulation is a very important scientific tool for explaining various phenomena and predicting the behavior of existing and designing materials under different conditions. The changes in the materials properties, caused by the space environment impact, are determined with structural parameters and processes that are related to different spatial scales: from the size of atoms and molecules to the size of macroobjects. To study nanomaterial response to the space environment, it is necessary to investigate and simulate processes occurring at nanoscale and to reveal various links between them and the processes, typical for the micro- and macroscale. Therefore, the multiscale simulation approach is needed, and different methods for various scales should be applied. In this presentation some approaches to multiscale computer simulation of the impact of some space environment components on nanomaterials are presented and discussed.

First-Principles Modeling of Hydrogen Storage in Metal Hydride Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

J. Karl Johnson

The objective of this project is to complement experimental efforts of MHoCE partners by using state-of-the-art theory and modeling to study the structure, thermodynamics, and kinetics of hydrogen storage materials. Specific goals include prediction of the heats of formation and other thermodynamic properties of alloys from first principles methods, identification of new alloys that can be tested experimentally, calculation of surface and energetic properties of nanoparticles, and calculation of kinetics involved with hydrogenation and dehydrogenation processes. Discovery of new metal hydrides with enhanced properties compared with existing materials is a critical need for the Metal Hydride Center of Excellence. Newmore » materials discovery can be aided by the use of first principles (ab initio) computational modeling in two ways: (1) The properties, including mechanisms, of existing materials can be better elucidated through a combined modeling/experimental approach. (2) The thermodynamic properties of novel materials that have not been made can, in many cases, be quickly screened with ab initio methods. We have used state-of-the-art computational techniques to explore millions of possible reaction conditions consisting of different element spaces, compositions, and temperatures. We have identified potentially promising single- and multi-step reactions that can be explored experimentally.« less

Do encapsulated heat storage materials really retain their original thermal properties?

PubMed

Chaiyasat, Preeyaporn; Noppalit, Sayrung; Okubo, Masayoshi; Chaiyasat, Amorn

2015-01-14

The encapsulation of Rubitherm®27 (RT27), which is one of the most common commercially supplied heat storage materials, by polystyrene (PS), polydivinyl benzene (PDVB) and polymethyl methacrylate (PMMA) was carried out using conventional radical microsuspension polymerization. The products were purified to remove free RT27 and free polymer particles without RT27. In the cases of PS and PDVB microcapsules, the latent heats of melting and crystallization for RT27 ( and , J/g-RT27) were clearly decreased by the encapsulation. On the other hand, those of the PMMA microcapsules were the same as pure RT27. A supercooling phenomenon was observed not only for PS and PDVB but also for the PMMA microcapsules. These results indicate that the thermal properties of the heat storage materials encapsulated depend on the type of polymer shells, i.e., encapsulation by polymer shell changes the thermal properties of RT27. This is quite different from the idea of other groups in the world, in which they discussed the thermal properties based on the ΔHm and ΔHc values expressed in J/g-capsule, assuming that the thermal properties of the heat storage materials are not changed by the encapsulation. Hereafter, this report should raise an alarm concerning the "wrong" common knowledge behind developing the encapsulation technology of heat storage materials.

Relationship between Surface Modifications of Nanoparticle and Invasion into Suspension Cells

NASA Astrophysics Data System (ADS)

Matsui, Y.; Sakai, N.; Tsuda, A.; Yoneda, M.

2011-07-01

Nanomaterials have a variety of properties for each material. There is little information available on which kinds of material properties have effects on toxicity and kinetics. This paper presents that a relationship between material properties and hazard data by undertaking a bibliographical survey at first. With respect to cytotoxicity, it probably depends mainly on the particle volume dose and to a certain degree on particle solubility. It can be concluded from these results that there is a relationship between material properties and hazard data. Many activities involving nano risk are occurring all over the world. Secondly, we assayed actually for cellular uptake of three kinds of Quantum dots (15 nm, 5.5×1012 particles/ml) to demonstrate our result of bibliographical survey. Three different surface modification quantum dots (non-modification, -COOH, -NH3) were mixed with floating Jurkat cells in each. After thirty minute, we washed these cells three times and detected fluorescence by flow cytometer. Almost all the carboxylate particles invaded a cell, about 60% aminated them also invaded and few non-modification particles were taken up. Nanomaterials are often very broadly categorized and named based upon their basic material composition or product shape. Our results confirm that we have to examine which physical-chemical properties affect some adverse effects for each nanomaterial.

Effect of Extrusion on the Mechanical and Rheological Properties of a Reinforced Poly(Lactic Acid): Reprocessing and Recycling of Biobased Materials

PubMed Central

Peinado, Víctor; Castell, Pere; García, Lidia; Fernández, Ángel

2015-01-01

The aim of this research paper is to study the behaviour of a common used biopolymer (Poly(Lactic Acid) (PLA)) after several reprocesses and how two different types of additives (a melt strength enhancer and a nanoadditive) affect its mechanical and rheological properties. Systematic extraction of extrudate samples from a twin-screw compounder was done in order to study the effect in the properties of the reprocessed material. Detailed rheological tests on a capillary rheometer as well as mechanical studies on a universal tensile machine after preparation of injected specimens were carried out. Results evidenced that PLA and reinforced PLA materials can be reprocessed and recycled without a remarkable loss in their mechanical properties. Several processing restrictions and specific phenomena were identified and are explained in the present manuscript. PMID:28793622

Correlation between the structure and the piezoelectric properties of lead-free (K,Na,Li)(Nb,Ta,Sb)O3 ceramics studied by XRD and Raman spectroscopy.

PubMed

Rubio-Marcos, Fernando; Marchet, Pascal; Romero, Juan José; Fernández, Jose F

2011-09-01

This article reviews on the use of Raman spectroscopy for the study of (K,Na,Li)(Nb,Ta,Sb)O(3) lead-free piezoceramics. Currently, this material appears to be one of the most interesting and promising alternatives to the well-known PZT piezoelectric materials. In this work, we prepare piezoceramics with different stoichiometries and study their structural, ferroelectric, and piezoelectric properties. By using both Raman spectroscopy and X-ray diffraction, we establish a direct correlation between the structure and the properties. The results demonstrate that the wavenumber of the A(1g) vibration is proportional to the tetragonality, the remnant polarization, and the piezoelectric coefficients of these materials. Thus, Raman spectroscopy appears as a very useful technique for a fast evaluation of the crystalline structure and the ferroelectric/ piezoelectric properties.

Influence of disorder on transfer characteristics of organic electrochemical transistors

NASA Astrophysics Data System (ADS)

Friedlein, Jacob T.; Rivnay, Jonathan; Dunlap, David H.; McCulloch, Iain; Shaheen, Sean E.; McLeod, Robert R.; Malliaras, George G.

2017-07-01

Organic electrochemical transistors (OECTs) are receiving a great deal of attention as transducers of biological signals due to their high transconductance. A ubiquitous property of these devices is the non-monotonic dependence of transconductance on gate voltage. However, this behavior is not described by existing models. Using OECTs made of materials with different chemical and electrical properties, we show that this behavior arises from the influence of disorder on the electronic transport properties of the organic semiconductor and occurs even in the absence of contact resistance. These results imply that the non-monotonic transconductance is an intrinsic property of OECTs and cannot be eliminated by device design or contact engineering. Finally, we present a model based on the physics of electronic conduction in disordered materials. This model fits experimental transconductance curves and describes strategies for rational material design to improve OECT performance in sensing applications.

Physicochemical and Electrophysical Properties of Metal/Semiconductor Containing Nanostructured Composites

NASA Astrophysics Data System (ADS)

Gerasimov, G. N.; Gromov, V. F.; Trakhtenberg, L. I.

2018-06-01

The properties of nanostructured composites based on metal oxides and metal-polymer materials are analyzed, along with ways of preparing them. The effect the interaction between metal and semiconductor nanoparticles has on the conductivity, photoconductivity, catalytic activity, and magnetic, dielectric, and sensor properties of nanocomposites is discussed. It is shown that as a result of this interaction, a material can acquire properties that do not exist in systems of isolated particles. The transfer of electrons between metal particles of different sizes in polymeric matrices leads to specific dielectric losses, and to an increase in the rate and a change in the direction of chemical reactions catalyzed by these particles. The interaction between metal-oxide semiconductor particles results in the electronic and chemical sensitization of sensor effects in nanostructured composite materials. Studies on creating molecular machines (Brownian motors), devices for magnetic recording of information, and high-temperature superconductors based on nanostructured systems are reviewed.

Effect of roll-compaction and milling conditions on granules and tablet properties.

PubMed

Perez-Gandarillas, Lucia; Perez-Gago, Ana; Mazor, Alon; Kleinebudde, Peter; Lecoq, Olivier; Michrafy, Abderrahim

2016-09-01

Dry granulation is an agglomeration process used to produce size-enlarged particles (granules), improving the handling properties of powders such as flowability. In this process, powders are compacted using a roll press to produce ribbons, which are milled in granules used further in the tableting process. The granule and tablet properties are influenced by the existence of different designs of the roll compactors, milling systems and the interaction between process parameters and raw material properties. The main objective of this work was to investigate how different roll-compaction conditions and milling process parameters impact on ribbons, granules and tablet properties, highlighting the role of the sealing system (cheek plates and rimmed roll). In this context, two common excipients differing in their mechanical behaviour (MCC and mannitol) are used. The study is based on the analysis of granule size distribution together with the characterization of loss of compactability during die compaction. Results show that the tensile strength of tablets is lower when using granules than when the raw materials are compressed. Moreover, the plastic material (MCC) is more sensitive than the brittle one (mannitol). Regarding the roll-force, it is observed that the higher the roll force, the lower the tensile strength of tablets from granulated material is. These findings are in agreement with the literature. The comparison of sealing systems shows that the rimmed-roll system leads to slightly stronger tablets than the use of cheek plates. In addition, the use of the rimmed-roll system reduces the amount of fines, in particular when high roll force is applied. Overall, it can be concluded that roll-compaction effect is predominant over the milling effect on the production of fines but less significant on the tablet properties. This study points out that the balance between a good flowability by reducing the amount of fines and appropriate tablet strength is achieved with rimmed-roll and the highest roll-force used. Copyright © 2016 Elsevier B.V. All rights reserved.

Biodegradable containers from green waste materials

NASA Astrophysics Data System (ADS)

Sartore, Luciana; Schettini, Evelia; Pandini, Stefano; Bignotti, Fabio; Vox, Giuliano; D'Amore, Alberto

2016-05-01

Novel biodegradable polymeric materials based on protein hydrolysate (PH), derived from waste products of the leather industry, and poly(ethylene glycol) diglycidyl ether (PEG) or epoxidized soybean oil (ESO) were obtained and their physico-chemical properties and mechanical behaviour were evaluated. Different processing conditions and the introduction of fillers of natural origin, as saw dust and wood flour, were used to tailor the mechanical properties and the environmental durability of the product. The biodegradable products, which are almost completely manufactured from renewable-based raw materials, look promising for several applications, particularly in agriculture for the additional fertilizing action of PH or in packaging.

Determining the relative toxicity and smoke obscuration of combustion products of mine combustibles. Report of Investigations/1990

DOE Office of Scientific and Technical Information (OSTI.GOV)

De Rosa, M.I.; Litton, C.D.

1990-01-01

Combustible materials, when burned, produce toxic gases and smoke, which may vary dramatically from one material to another, with resultant different total toxicity and smoke obscuration levels. The U.S. Bureau of Mines report presents smoke property data acquired for a variety of mine combustibles and shows that there exists a correlation between the smoke properties, the relative toxicity, and the smoke obscuration levels of those combustibles tested. These correlations can be used to devise simple, standard tests for determining the toxic and smoke obscuration hazards of mine materials during fire.

Antibacterial, physical and mechanical properties of flowable resin composites containing zinc oxide nanoparticles.

PubMed

Tavassoli Hojati, Sara; Alaghemand, Homayoon; Hamze, Faeze; Ahmadian Babaki, Fateme; Rajab-Nia, Ramazan; Rezvani, Mohammad Bagher; Kaviani, Mehrnoosh; Atai, Mohammad

2013-05-01

The aim of this study is evaluating the antibacterial activity of resin composites containing ZnO nanoparticles against Streptococcus mutans and examining their physical and mechanical properties. The properties of flowable resin composites containing 0-5wt.% nano-ZnO are investigated using different tests: Although the agar diffusion test reveals no significant difference between the groups, the direct contact test demonstrates that by increasing the nanoparticle content, the bacterial growth is significantly diminished (p<0.05). In the aging test, however, the antibacterial properties reduce significantly (p<0.05). The flexural strength and compressive modulus remains unchanged by incorporation of nanoparticles (p>0.05) while the compressive strength and flexural modulus significantly increase (p<0.05). The ZnO containing resins show significantly lower depth of cure (p<0.05), and higher bond strength (p<0.05). There is no significant difference between the degrees of conversion, measured by FTIR technique, of the groups (p>0.05). Production of a dental resin composite with antibacterial activity without significant sacrificing effect on the mechanical properties is desirable in dental material science. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Advances in Porous Biomaterials for Dental and Orthopaedic Applications

PubMed Central

Mour, Meenakshi; Das, Debarun; Winkler, Thomas; Hoenig, Elisa; Mielke, Gabriela; Morlock, Michael M.; Schilling, Arndt F.

2010-01-01

The connective hard tissues bone and teeth are highly porous on a micrometer scale, but show high values of compression strength at a relatively low weight. The fabrication of porous materials has been actively researched and different processes have been developed that vary in preparation complexity and also in the type of porous material that they produce. Methodologies are available for determination of pore properties. The purpose of the paper is to give an overview of these methods, the role of porosity in natural porous materials and the effect of pore properties on the living tissues. The minimum pore size required to allow the ingrowth of mineralized tissue seems to be in the order of 50 µm: larger pore sizes seem to improve speed and depth of penetration of mineralized tissues into the biomaterial, but on the other hand impair the mechanical properties. The optimal pore size is therefore dependent on the application and the used material.

Chapter 19: Catalysis by Metal Carbides and Nitrides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schaidle, Joshua A; Nash, Connor P; Yung, Matthew M

Early transition metal carbides and nitrides (ETMCNs), materials in which carbon or nitrogen occupies interstitial sites within a parent metal lattice, possess unique physical and chemical properties that motivate their use as catalysts. Specifically, these materials possess multiple types of catalytic sites, including metallic, acidic, and basic sites, and as such, exhibit reactivities that differ from their parent metals. Moreover, their surfaces are dynamic under reaction conditions. This chapter reviews recent (since 2010) experimental and computational investigations into the catalytic properties of ETMCN materials for applications including biomass conversion, syngas and CO2 upgrading, petroleum and natural gas refining, and electrocatalyticmore » energy conversion, energy storage, and chemicals production, and attempts to link catalyst performance to active site identity/surface structure in order to elucidate the present level of understanding of structure-function relationships for these materials. The chapter concludes with a perspective on leveraging the unique properties of these materials to design and develop improved catalysts through a dedicated, multidisciplinary effort.« less

Ultra-low temperature curable nano-silver conductive adhesive for piezoelectric composite material

NASA Astrophysics Data System (ADS)

Yan, Chao; Liao, Qingwei; Zhou, Xingli; Wang, Likun; Zhong, Chao; Zhang, Di

2018-01-01

Limited by the low thermal resistance of composite material, ultra-low temperature curable conductive silver adhesive with curing temperature less than 100 °C needed urgently for the surface conduction treatment of piezoelectric composite material. An ultra-low temperature curable nano-silver conductive adhesive with high adhesion strength for the applications of piezoelectric composite material was investigated. The crystal structure of cured adhesive, SEM/EDS analysis, thermal analysis, adhesive properties and conductive properties of different content of nano-silver filler or micron-silver doping samples were studied. The results show that with 60 wt.% nano-silver filler the ultra-low temperature curable conductive silver adhesive had the relatively good conductivity as volume resistivity of 2.37 × 10-4 Ω cm, and good adhesion strength of 5.13 MPa. Minor micron-doping (below 15 wt.%) could improve conductivity, but would decrease other properties. The ultra-low temperature curable nano-silver conductive adhesive could successfully applied to piezoelectric composite material.

The influence of heat treatment on properties of cold rolled alloyed steel and nickel superalloys sheets used in aircraft industry

NASA Astrophysics Data System (ADS)

Zaba, K.; Dul, I.; Puchlerska, S.

2017-02-01

Superalloys based on nickel and selected steels are widely used in the aerospace industry, because of their excellent mechanical properties, heat resistance and creep resistance. Metal sheets of these materials are plastically deformed and applied, inter alia, to critical components of aircraft engines. Due to their chemical composition these materials are hardly deformable. There are various methods to improve the formability of these materials, including plastic deformation at an elevated or high temperature, or a suitable heat treatment before forming process. The paper presents results of the metal sheets testing after heat treatment. For the research, sheets of two types of nickel superalloys type Inconel and of three types of steel were chosen. The materials were subjected to multivariate heat treatment at different temperature range and time. After this step, mechanical properties were examined according to the metal sheet rolling direction. The results were compared and the optimal type of pre-trial softening heat treatment for each of the materials was determined.

Bioactive Nanocomposites for Tissue Repair and Regeneration: A Review

PubMed Central

Bramhill, Jane; Ross, Sukunya; Ross, Gareth

2017-01-01

This review presents scientific findings concerning the use of bioactive nanocomposites in the field of tissue repair and regeneration. Bioactivity is the ability of a material to incite a specific biological reaction, usually at the boundary of the material. Nanocomposites have been shown to be ideal bioactive materials due the many biological interfaces and structures operating at the nanoscale. This has resulted in many researchers investigating nanocomposites for use in bioapplications. Nanocomposites encompass a number of different structures, incorporating organic-inorganic, inorganic-inorganic and bioinorganic nanomaterials and based upon ceramic, metallic or polymeric materials. This enables a wide range of properties to be incorporated into nanocomposite materials, such as magnetic properties, MR imaging contrast or drug delivery, and even a combination of these properties. Much of the classical research was focused on bone regeneration, however, recent advances have enabled further use in soft tissue body sites too. Despite recent technological advances, more research is needed to further understand the long-term biocompatibility impact of the use of nanoparticles within the human body. PMID:28085054

Charting the complete elastic properties of inorganic crystalline compounds

PubMed Central

de Jong, Maarten; Chen, Wei; Angsten, Thomas; Jain, Anubhav; Notestine, Randy; Gamst, Anthony; Sluiter, Marcel; Krishna Ande, Chaitanya; van der Zwaag, Sybrand; Plata, Jose J; Toher, Cormac; Curtarolo, Stefano; Ceder, Gerbrand; Persson, Kristin A.; Asta, Mark

2015-01-01

The elastic constant tensor of an inorganic compound provides a complete description of the response of the material to external stresses in the elastic limit. It thus provides fundamental insight into the nature of the bonding in the material, and it is known to correlate with many mechanical properties. Despite the importance of the elastic constant tensor, it has been measured for a very small fraction of all known inorganic compounds, a situation that limits the ability of materials scientists to develop new materials with targeted mechanical responses. To address this deficiency, we present here the largest database of calculated elastic properties for inorganic compounds to date. The database currently contains full elastic information for 1,181 inorganic compounds, and this number is growing steadily. The methods used to develop the database are described, as are results of tests that establish the accuracy of the data. In addition, we document the database format and describe the different ways it can be accessed and analyzed in efforts related to materials discovery and design. PMID:25984348

Development of orthotropic birefringent materials for photoelastic stress analysis

NASA Technical Reports Server (NTRS)

Daniel, I. M.; Niiro, T.; Koller, G. M.

1981-01-01

Materials were selected and fabrication procedures developed for orthotropic birefringent materials. An epoxy resin (Maraset 658/558 system) was selected as the matrix material. Fibers obtained from style 3733 glass cloth and type 1062 glass roving were used as reinforcement. Two different fabrication procedures were used. In the first one, layers of unidirectional fibers removed from the glass cloth were stacked, impregnated with resin, bagged and cured in the autoclave at an elevated temperature. In the second procedure, the glass roving was drywound over metal frames, impregnated with resin and cured at room temperature under pressure and vacuum in an autoclave. Unidirectional, angle-ply and quasi-isotropic laminates of two thicknesses and with embedded flaws were fabricated. The matrix and the unidirectional glass/epoxy material were fully characterized. The density, fiber volume ratio, mechanical, and optical properties were determined. The fiber volume ratio was over 0.50. Birefringent properties were in good agreement with predictions based on a stress proportioning concept and also, with one exception, with properties predicted by a finite element analysis.

Direct comparison of nanoindentation and tensile test results on reactor-irradiated materials

DOE PAGES

Krumweide, David L; Yamamoto, Takuya; Saleh, Tarik A.; ...

2018-03-13

Nanoindentation testing has been used for decades to assess materials on a local scale and to obtain fundamental mechanical property parameters. Nuclear materials research often faces the challenge of testing rather small samples due to the hazardous nature, limited space in reactors, and shallow ion-irradiated zones, fostering the need for small-scale mechanical testing (SSMT). As such, correlating the results from SSMT to bulk properties is particularly of interest. Here, this study compares macroscopic tensile test data (yield and flow stresses) to nanoindentation data (hardness) obtained on a number of different neutron-irradiated materials in order to understand the scaling behavior onmore » radiation-damaged samples.« less

Innovative potential of plasma technology

NASA Astrophysics Data System (ADS)

Budaev, V. P.

2017-11-01

The review summarizes recent experimental observations of materials exposed to extreme hot plasma loads in fusion devices and plasma facilities with high-temperature plasma. Plasma load on the material in such devices lead to the stochastic clustering and fractal growth of the surface on scales from tens of nanometers to hundreds of micrometers forming statistical self-similarity of the surface roughness with extremely high specific area. Statistical characteristics of hierarchical granularity and scale invariance of such materials surface qualitatively differ from the properties of the roughness of the ordinary Brownian surface which provides a potential of innovative plasma technologies for synthesis of new nanostructured materials with programmed roughness properties, for hypersonic technologies, for biotechnology and biomedical applications.

Direct comparison of nanoindentation and tensile test results on reactor-irradiated materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krumweide, David L; Yamamoto, Takuya; Saleh, Tarik A.

Nanoindentation testing has been used for decades to assess materials on a local scale and to obtain fundamental mechanical property parameters. Nuclear materials research often faces the challenge of testing rather small samples due to the hazardous nature, limited space in reactors, and shallow ion-irradiated zones, fostering the need for small-scale mechanical testing (SSMT). As such, correlating the results from SSMT to bulk properties is particularly of interest. Here, this study compares macroscopic tensile test data (yield and flow stresses) to nanoindentation data (hardness) obtained on a number of different neutron-irradiated materials in order to understand the scaling behavior onmore » radiation-damaged samples.« less

Divergent growth strategies between red algae and kelps influence biomechanical properties.

PubMed

Krumhansl, Kira A; Demes, Kyle W; Carrington, Emily; Harley, Christopher D G

2015-11-01

Morphology and material properties are the main components of the mechanical design of organisms, with species groups developing different optimization strategies in the context of their physical environment. For intertidal and subtidal seaweeds, possessing highly flexible and extensible tissues allows individuals to bend and reconfigure in flow, thereby reducing drag. Previous research has shown that aging may compromise these qualities. Tissue age increases with distance from the blade's meristem, which differs in its position on kelps and red algae. Here, we assess whether longitudinal patterns of blade material properties differ between these two algal groups according to tissue age. We performed tensile tests on tissues samples excised from various positions along the extent of blades in nine kelp species (basal growth) and 15 species of red algae (apical growth). We found that older tissues were less flexible and extensible than younger tissues in all species tested. As predicted, tissue near the basal meristem in kelp was more flexible and extensible than older tissue at the blade's distal end. The opposite pattern was observed for red algae, with the most flexible and extensible tissues found near the apical meristem at the distal ends of blades. We propose that divergent patterns in the distribution of material properties along blades may have different consequences for the performance of kelps and red algae. The positioning of younger tissues at the blade base for kelps may enable these species to attain larger body sizes in wave-swept habitats. © 2015 Botanical Society of America.

The effect of collagen crosslinking on the biphasic poroviscoelastic cartilage properties determined from a semi-automated microindentation protocol for stress relaxation.

PubMed

McGann, Megan E; Bonitsky, Craig M; Ovaert, Timothy C; Wagner, Diane R

2014-06-01

Given the important role of the collagenous structure in cartilage mechanics, there is considerable interest in the relationship between collagen crosslinking and the mechanical behavior of the cartilage matrix. While crosslink-induced alterations to the elastic modulus of cartilage have been described, changes to time-dependent behavior have not yet been determined. The objective of the study was to quantify changes to cartilage material properties, including viscoelastic coefficients, with crosslinking via indentation. To accomplish this, a semi-autonomous microindentation stress relaxation protocol was first developed, validated and then applied to cartilage specimens before and after crosslinking. The change in mechanical properties with crosslinking was analyzed both in the unloading portions of the test via the Oliver-Pharr method and in the holding portion with an inverse iterative finite element model that represented cartilage as a biphasic poroviscoelastic material. Although both techniques suggested a similar increase in equilibrium modulus in the crosslinked specimens as compared to the controls, distinct differences in the control specimens were apparent, suggesting that the two different techniques may be capturing different aspects of the material behavior. No differences in time-dependent properties were observed between the crosslinked and the control specimens. These results give further insight into the effects of crosslinking in cartilage mechanical behavior. Additionally, the microindentation stress relaxation protocol may enable increased automation for high-throughput testing. Copyright © 2014 Elsevier Ltd. All rights reserved.

Metal Nanoparticles Embedded in Cellulose Nanocrystal Based Films: Material Properties and Post-use Analysis.

PubMed

Lizundia, Erlantz; Goikuria, Uribarri; Vilas, José Luis; Cristofaro, Francesco; Bruni, Giovanna; Fortunati, Elena; Armentano, Ilaria; Visai, Livia; Torre, Luigi

2018-04-25

The dispersion of nanoparticles having different size-, shape-, and composition-dependent properties is an exciting approach to design and synthesize multifunctional materials and devices. This work shows a detailed investigation of the preparation and properties of free-standing nanocomposite films based on cellulose nanocrystals (CNC) loaded with three different types of metal nanoparticles. CNC-based nanocomposites having zinc oxide (ZnO), titanium dioxide (TiO 2 ), and silver oxide (Ag 2 O) have been obtained through evaporation-induced self-assembly (EISA) in acqueous solution. Morphological and optical characteristics, chemical properties, wettability, and antimicrobial assays of the produced films were conducted. Furthermore, disintegrability in composting condition of CNC based nanocomposites was here investigated for the first time. The morphological observations revealed the formation of a chiral nematic structure with uniformly distributed nanoparticles. The bionanocomposite films based on the metal nanoparticles had effective antimicrobial activity, killing both Escherichia coli RB ( E. coli RB) and Staphylococcus aureus 8325-4 ( S. aureus 8325-4). The simplicity method of film preparation, the large quantity of cellulose in the world, and the free-standing nature of the nanocomposite films offer highly advantageous characteristics that can for the new development of multifunctional materials.

Review on measurement techniques of transport properties of nanowires Additions and Corrections. See DOI:10.1039/C3NR03242F Click here for additional data file.

PubMed Central

Rojo, Miguel Muñoz; Calero, Olga Caballero; Lopeandia, A. F.; Rodriguez-Viejo, J.

2013-01-01

Physical properties at the nanoscale are novel and different from those in bulk materials. Over the last few decades, there has been an ever growing interest in the fabrication of nanowire structures for a wide variety of applications including energy generation purposes. Nevertheless, the study of their transport properties, such as thermal conductivity, electrical conductivity or Seebeck coefficient, remains an experimental challenge. For instance, in the particular case of nanostructured thermoelectrics, theoretical calculations have shown that nanowires offer a promising way of enhancing the hitherto low efficiency of these materials in the conversion of temperature differences into electricity. Therefore, within the thermoelectrical community there has been a great experimental effort in the measurement of these quantities in actual nanowires. The measurements of these properties at the nanoscale are also of interest in fields other than energy, such as electrical components for microchips, field effect transistors, sensors, and other low scale devices. For all these applications, knowing the transport properties is mandatory. This review deals with the latest techniques developed to perform the measurement of these transport properties in nanowires. A thorough overview of the most important and modern techniques used for the characterization of different kinds of nanowires will be shown. PMID:24113712

Investigation of a novel approach for the cross-linking characterization of SU-8 photoresist materials by means of optical dispersion measurements

NASA Astrophysics Data System (ADS)

Taudt, Ch.; Baselt, T.; Koch, E.; Hartmann, P.

2014-03-01

The increase in efficiency and precision in the production of semiconductor structures under the use of polymeric materials like SU-8 is crucial in securing the technological innovation within this industry. The manufacturing of structures on wafers demands a high quality of materials, tools and production processes. In particular, deviations in the materials' parameters (e.g. cross-linking state, density or mechanical properties) could lead to subsequent problems such as a reduced lifetime of structures and systems. In particular problems during the soft and post-exposure bake process can lead to an inhomogeneous distribution of material properties. This paper describes a novel approach for the characterization of SU-8 material properties in relation to a second epoxy-based material of different cross-linking by the measurement of optical dispersion within the material. A white-light interferometer was used. In particular the setup consisted of a white-light source, a Michelson-type interferometer and a spectrometer. The investigation of the dispersion characteristics was carried out by the detection of the equalization wavelength for different positions of the reference arm in a range from 400 to 900 nm. The measured time delay due to dispersion ranges from 850 to 1050 ps/m. For evaluation purposes a 200μm SU-8 sample was characterized in the described setup regarding its dispersion characteristics in relation to bulk epoxy material. The novel measurement approach allowed a fast and high-resolution material characterization for SU-8 micro structures which was suitable for integration in production lines. The outlook takes modifications of the experimental setup regarding on-wafer measurements into account.

Behavior of Bubble Interfaces Stabilized by Particles of Different Densities.

PubMed

Bournival, Ghislain; Ata, Seher; Wanless, Erica J

2016-06-28

Stability of bubbles laden with particles of different densities was investigated. Capillary-held bubbles were produced and coated with particles across the density range of 1.2-3.6 g·cm(-3). The materials used were poly(methyl methacrylate) (PMMA), glass, and anatase. The interaction of the bubbles, once brought into contact, was monitored using high-speed video recording. Visual inspection indicated that denser particles were more easily displaced during the contact of the bubbles and therefore the PMMA particles provided a particle barrier more resistant to coalescence. The coalescence events yielded information on the surface properties of the bubble and the detachment of particles. The attached particles commonly dampen the oscillation of the coalesced bubbles through viscous drag and change in the surface properties (e.g., area-exclusion principle). The dampening of the oscillation generally leads to a reduced mass of particles detaching from the bubble surface. It was found that the different materials investigated did not offer clear evidence of the effect of particle detachment on the bubble surface properties in the present systems. On the other hand, the detachment of different particle materials seemed to be consistent with one another when comparing the attachment and detachment forces exerted on the particles based on their density, size, and hydrophobicity. It was concluded that particles of lower density are more effective in stabilizing interfaces, and thus particle density is an important parameter in the selection of materials for the handling of dispersions.

Cluster-assembled metallic glasses

PubMed Central

2013-01-01

A bottom-up approach to nanofabricate metallic glasses from metal clusters as building blocks is presented. Considering metallic glasses as a subclass of cluster-assembled materials, the relation between the two lively fields of metal clusters and metallic glasses is pointed out. Deposition of selected clusters or collections of them, generated by state-of-the-art cluster beam sources, could lead to the production of a well-defined amorphous material. In contrast to rapidly quenched glasses where only the composition of the glass can be controlled, in cluster-assembled glasses, one can precisely control the structural building blocks. Comparing properties of glasses with similar compositions but differing in building blocks and therefore different in structure will facilitate the study of structure–property correlation in metallic glasses. This bottom-up method provides a novel alternative path to the synthesis of glassy alloys and will contribute to improving fundamental understanding in the field of metallic glasses. It may even permit the production of glassy materials for alloys that cannot be quenched rapidly enough to circumvent crystallization. Additionally, gaining deeper insight into the parameters governing the structure–property relation in metallic glasses can have a great impact on understanding and design of other cluster-assembled materials. PMID:23899019

Thermophysical and Mechanical Properties of Hardened Cement Paste with Microencapsulated Phase Change Materials for Energy Storage.

PubMed

Cui, Hongzhi; Liao, Wenyu; Memon, Shazim Ali; Dong, Biqin; Tang, Waiching

2014-12-16

In this research, structural-functional integrated cement-based materials were prepared by employing cement paste and a microencapsulated phase change material (MPCM) manufactured using urea-formaldehyde resin as the shell and paraffin as the core material. The encapsulation ratio of the MPCM could reach up to 91.21 wt%. Thermal energy storage cement pastes (TESCPs) incorporated with different MPCM contents (5%, 10%, 15%, 20% and 25% by weight of cement) were developed, and their thermal and mechanical properties were studied. The results showed that the total energy storage capacity of the hardened cement specimens with MPCM increased by up to 3.9-times compared with that of the control cement paste. The thermal conductivity at different temperature levels (35-36 °C, 55-56 °C and 72-74 °C) decreased with the increase of MPCM content, and the decrease was the highest when the temperature level was 55-56 °C. Moreover, the compressive strength, flexural strength and density of hardened cement paste decreased with the increase in MPCM content linearly. Among the evaluated properties, the compressive strength of TESCPs had a larger and faster degradation with the increase of MPCM content.

Processing and characterization of natural cellulose fibers/thermoset polymer composites.

PubMed

Thakur, Vijay Kumar; Thakur, Manju Kumari

2014-08-30

Recently natural cellulose fibers from different biorenewable resources have attracted the considerable attraction of research community all around the globe owing to their unique intrinsic properties such as biodegradability, easy availability, environmental friendliness, flexibility, easy processing and impressive physico-mechanical properties. Natural cellulose fibers based materials are finding their applications in a number of fields ranging from automotive to biomedical. Natural cellulose fibers have been frequently used as the reinforcement component in polymers to add the specific properties in the final product. A variety of cellulose fibers based polymer composite materials have been developed using various synthetic strategies. Seeing the immense advantages of cellulose fibers, in this article we discuss the processing of biorenewable natural cellulose fibers; chemical functionalization of cellulose fibers; synthesis of polymer resins; different strategies to prepare cellulose based green polymer composites, and diverse applications of natural cellulose fibers/polymer composite materials. The article provides an in depth analysis and comprehensive knowledge to the beginners in the field of natural cellulose fibers/polymer composites. The prime aim of this review article is to demonstrate the recent development and emerging applications of natural cellulose fibers and their polymer materials. Copyright © 2014 Elsevier Ltd. All rights reserved.

PET and PVC separation with hyperspectral imagery.

PubMed

Moroni, Monica; Mei, Alessandro; Leonardi, Alessandra; Lupo, Emanuela; Marca, Floriana La

2015-01-20

Traditional plants for plastic separation in homogeneous products employ material physical properties (for instance density). Due to the small intervals of variability of different polymer properties, the output quality may not be adequate. Sensing technologies based on hyperspectral imaging have been introduced in order to classify materials and to increase the quality of recycled products, which have to comply with specific standards determined by industrial applications. This paper presents the results of the characterization of two different plastic polymers--polyethylene terephthalate (PET) and polyvinyl chloride (PVC)--in different phases of their life cycle (primary raw materials, urban and urban-assimilated waste and secondary raw materials) to show the contribution of hyperspectral sensors in the field of material recycling. This is accomplished via near-infrared (900-1700 nm) reflectance spectra extracted from hyperspectral images acquired with a two-linear-spectrometer apparatus. Results have shown that a rapid and reliable identification of PET and PVC can be achieved by using a simple two near-infrared wavelength operator coupled to an analysis of reflectance spectra. This resulted in 100% classification accuracy. A sensor based on this identification method appears suitable and inexpensive to build and provides the necessary speed and performance required by the recycling industry.

Comparison of Martian Meteorites and Martian Regolith as Shield Materials for Galactic Cosmic Rays

NASA Technical Reports Server (NTRS)

Kim, Myung-Hee Y.; Thibeault, Sheila A.; Simonsen, Lisa C.; Wilson, John W.

1998-01-01

Theoretical calculations of radiation attenuation due to energetic galactic cosmic rays behind Martian rock and Martian regolith material have been made to compare their utilization as shields for advanced manned missions to Mars because the detailed chemical signature of Mars is distinctly different from Earth. The modified radiation fields behind the Martian rocks and the soil model were generated by solving the Boltzmann equation using a HZETRN system with the 1977 Solar Minimum environmental model. For the comparison of the attenuation characteristics, dose and dose equivalent are calculated for the five different subgroups of Martian rocks and the Martian regolith. The results indicate that changes in composition of subgroups of Martian rocks have negligible effects on the overall shielding properties because of the similarity of their constituents. The differences for dose and dose equivalent of these materials relative to those of Martian regolith are within 0.5 and 1 percent, respectively. Therefore, the analysis of Martian habitat construction options using in situ materials according to the Martian regolith model composition is reasonably accurate. Adding an epoxy to Martian regolith, which changes the major constituents of the material, enhances shielding properties because of the added hydrogenous constituents.

PET and PVC Separation with Hyperspectral Imagery

PubMed Central

Moroni, Monica; Mei, Alessandro; Leonardi, Alessandra; Lupo, Emanuela; La Marca, Floriana

2015-01-01

Traditional plants for plastic separation in homogeneous products employ material physical properties (for instance density). Due to the small intervals of variability of different polymer properties, the output quality may not be adequate. Sensing technologies based on hyperspectral imaging have been introduced in order to classify materials and to increase the quality of recycled products, which have to comply with specific standards determined by industrial applications. This paper presents the results of the characterization of two different plastic polymers—polyethylene terephthalate (PET) and polyvinyl chloride (PVC)—in different phases of their life cycle (primary raw materials, urban and urban-assimilated waste and secondary raw materials) to show the contribution of hyperspectral sensors in the field of material recycling. This is accomplished via near-infrared (900–1700 nm) reflectance spectra extracted from hyperspectral images acquired with a two-linear-spectrometer apparatus. Results have shown that a rapid and reliable identification of PET and PVC can be achieved by using a simple two near-infrared wavelength operator coupled to an analysis of reflectance spectra. This resulted in 100% classification accuracy. A sensor based on this identification method appears suitable and inexpensive to build and provides the necessary speed and performance required by the recycling industry. PMID:25609050

Determination of tissue equivalent materials of a physical 8-year-old phantom for use in computed tomography

NASA Astrophysics Data System (ADS)

Akhlaghi, Parisa; Miri Hakimabad, Hashem; Rafat Motavalli, Laleh

2015-07-01

This paper reports on the methodology applied to select suitable tissue equivalent materials of an 8-year phantom for use in computed tomography (CT) examinations. To find the appropriate tissue substitutes, first physical properties (physical density, electronic density, effective atomic number, mass attenuation coefficient and CT number) of different materials were studied. Results showed that, the physical properties of water and polyurethane (as soft tissue), B-100 and polyvinyl chloride (PVC) (as bone) and polyurethane foam (as lung) agree more with those of original tissues. Then in the next step, the absorbed doses in the location of 25 thermoluminescent dosimeters (TLDs) as well as dose distribution in one slice of phantom were calculated for original and these proposed materials by Monte Carlo simulation at different tube voltages. The comparisons suggested that at tube voltages of 80 and 100 kVp using B-100 as bone, water as soft tissue and polyurethane foam as lung is suitable for dosimetric study in pediatric CT examinations. In addition, it was concluded that by considering just the mass attenuation coefficient of different materials, the appropriate tissue equivalent substitutes in each desired X-ray energy range could be found.

Development of Dielectric Material with Ceramic Matrix Composite (CMC) Produced from Kaolinite and CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yin, Wong Swee; Hassan, Jumiah; Hashim, Mansor

Ceramic matrix composites (CMC) combine reinforcing ceramic phases, CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO) with a ceramic matrix, kaolinite to create materials with new and superior properties. 10% and 20% CCTO were prepared by using a conventional solid state reaction method. CMC samples were pre-sintered at 800 deg. C and sintered at 1000 deg. C. The dielectric properties of samples were measured using HP 4192A LF Impedance Analyzer. Microstructures of the samples were observed using an optical microscope. XRD was used to determine the crystalline structure of the samples. The AFM showed the morphology of the samples. The results showed thatmore » the dielectric constant and dielectric loss factor of both samples are frequency dependent. At 10 Hz, the dielectric constant is 10{sup 11} for both samples. The CMC samples were independent with temperature with low dielectric constant in the frequency range of 10{sup 4}-10{sup 6} Hz. Since the CMC samples consist of different amount of kaolinite, so each sample exhibit different defect mechanism. Different reaction may occur for different composition of material. The effects of processing conditions on the microstructure and electrical properties of CMC are also discussed.« less

Sediment fingerprinting experiments to test the sensitivity of multivariate mixing models

NASA Astrophysics Data System (ADS)

Gaspar, Leticia; Blake, Will; Smith, Hugh; Navas, Ana

2014-05-01

Sediment fingerprinting techniques provide insight into the dynamics of sediment transfer processes and support for catchment management decisions. As questions being asked of fingerprinting datasets become increasingly complex, validation of model output and sensitivity tests are increasingly important. This study adopts an experimental approach to explore the validity and sensitivity of mixing model outputs for materials with contrasting geochemical and particle size composition. The experiments reported here focused on (i) the sensitivity of model output to different fingerprint selection procedures and (ii) the influence of source material particle size distributions on model output. Five soils with significantly different geochemistry, soil organic matter and particle size distributions were selected as experimental source materials. A total of twelve sediment mixtures were prepared in the laboratory by combining different quantified proportions of the < 63 µm fraction of the five source soils i.e. assuming no fluvial sorting of the mixture. The geochemistry of all source and mixture samples (5 source soils and 12 mixed soils) were analysed using X-ray fluorescence (XRF). Tracer properties were selected from 18 elements for which mass concentrations were found to be significantly different between sources. Sets of fingerprint properties that discriminate target sources were selected using a range of different independent statistical approaches (e.g. Kruskal-Wallis test, Discriminant Function Analysis (DFA), Principal Component Analysis (PCA), or correlation matrix). Summary results for the use of the mixing model with the different sets of fingerprint properties for the twelve mixed soils were reasonably consistent with the initial mixing percentages initially known. Given the experimental nature of the work and dry mixing of materials, geochemical conservative behavior was assumed for all elements, even for those that might be disregarded in aquatic systems (e.g. P). In general, the best fits between actual and modeled proportions were found using a set of nine tracer properties (Sr, Rb, Fe, Ti, Ca, Al, P, Si, K, Si) that were derived using DFA coupled with a multivariate stepwise algorithm, with errors between real and estimated value that did not exceed 6.7 % and values of GOF above 94.5 %. The second set of experiments aimed to explore the sensitivity of model output to variability in the particle size of source materials assuming that a degree of fluvial sorting of the resulting mixture took place. Most particle size correction procedures assume grain size affects are consistent across sources and tracer properties which is not always the case. Consequently, the < 40 µm fraction of selected soil mixtures was analysed to simulate the effect of selective fluvial transport of finer particles and the results were compared to those for source materials. Preliminary findings from this experiment demonstrate the sensitivity of the numerical mixing model outputs to different particle size distributions of source material and the variable impact of fluvial sorting on end member signatures used in mixing models. The results suggest that particle size correction procedures require careful scrutiny in the context of variable source characteristics.

The Origin of Hierarchical Structure in Self-Assembled Graphene Oxide Papers and the Effect on Mechanical Properties

NASA Astrophysics Data System (ADS)

Nandy, Krishanu

The quest for new materials with ever improving properties has motivated interest in bulk nanostructured materials. Graphene, a two-dimensional sheet of hexagonally arranged carbon atoms, has been of particular interest given its exceptional mechanical, thermal, optical and electrical properties. Graphene oxide is a chemically modified form of graphene in which the honeycomb lattice of carbon atoms is decorated with oxygen bearing functional groups. Graphene oxide represents a facile route for the production of large quantities of graphene based materials, is stable in aqueous and polar organic solvents and has the potential for further chemical modification. In this dissertation, the origin and influence of hierarchical structure on the mechanical properties of graphene oxide paper and graphene oxide paper based materials has been investigated. Free-standing papers derived from graphene oxide are of interest as structural materials due to their impressive mechanical properties. While studies have investigated the mechanical properties of graphene oxide papers, little is known about the formation mechanism. Using a series of flash-freezing experiments on graphene oxide papers undergoing formation, a stop-motion animation of the fabrication process was obtained. The results explain the origin of the hierarchical nature of graphene oxide papers and provide a method for the tailoring of graphene oxide based materials. An in depth study of fusion of graphene oxide papers demonstrates a simple single-step route for the fabrication of practical materials derived from graphene oxide papers. Fused papers retain the properties of constituent papers allowing for the fabrication of mechanical heterostructures that replicate the hierarchical nature of natural materials. The contribution of the hierarchical nature of graphene oxide papers to the mechanical properties was examined by comparing papers formed by two different mechanisms. The intermediate length scale structures were found to play a key role in yielding tough papers with high failure stress. Finally, efforts to investigate the microstructural mechanisms that govern the mechanical properties of graphene oxide papers by 3D printing of a tensile tester are detailed. It is intended to release the design of the tensile tester to the community in an effort to reduce cost and improve availability of lab equipment.

Dielectric properties and Raman spectra of ZnO from a first principles finite-differences/finite-fields approach

PubMed Central

Calzolari, Arrigo; Nardelli, Marco Buongiorno

2013-01-01

Using first principles calculations based on density functional theory and a coupled finite-fields/finite-differences approach, we study the dielectric properties, phonon dispersions and Raman spectra of ZnO, a material whose internal polarization fields require special treatment to correctly reproduce the ground state electronic structure and the coupling with external fields. Our results are in excellent agreement with existing experimental measurements and provide an essential reference for the characterization of crystallinity, composition, piezo- and thermo-electricity of the plethora of ZnO-derived nanostructured materials used in optoelectronics and sensor devices. PMID:24141391

Leaching behaviour and mechanical properties of copper flotation waste in stabilized/solidified products.

PubMed

Mesci, Başak; Coruh, Semra; Ergun, Osman Nuri

2009-02-01

This research describes the investigation of a cement-based solidification/stabilization process for the safe disposal of copper flotation waste and the effect on cement properties of the addition of copper flotation waste (CW) and clinoptilolite (C). In addition to the reference mixture, 17 different mixtures were prepared using different proportions of CW and C. Physical properties such as setting time, specific surface area and compressive strength were determined and compared to a reference mixture and Turkish standards (TS). Different mixtures with the copper flotation waste portion ranging from 2.5 to 12.5% by weight of the mixture were tested for copper leachability. The results show that as cement replacement materials especially clinoptilolite had clear effects on the mechanical properties. Substitution of 5% copper flotation waste for Portland cement gave a similar strength performance to the reference mixture. Higher copper flotation waste addition such as 12.5% replacement yielded lower strength values. As a result, copper flotation waste and clinoptilolite can be used as cementitious materials, and copper flotation waste also can be safely stabilized/solidified in a cement-based solidification/stabilization system.

A Look Inside Argonne's Center for Nanoscale Materials

ScienceCinema

Divan, Ralu; Rosenthal, Dan; Rose, Volker; Wai Hla

2018-05-23

At a very small, or "nano" scale, materials behave differently. The study of nanomaterials is much more than miniaturization - scientists are discovering how changes in size change a material's properties. From sunscreen to computer memory, the applications of nanoscale materials research are all around us. Researchers at Argonne's Center for Nanoscale Materials are creating new materials, methods and technologies to address some of the world's greatest challenges in energy security, lightweight but durable materials, high-efficiency lighting, information storage, environmental stewardship and advanced medical devices.

Physical and chemical characterization of biochars derived from different agricultural residues

NASA Astrophysics Data System (ADS)

Jindo, K.; Mizumoto, H.; Sawada, Y.; Sanchez-Monedero, M. A.; Sonoki, T.

2014-12-01

Biochar is widely recognized as an efficient tool for carbon sequestration and soil fertility. The understanding of its chemical and physical properties, which are strongly related to the type of the initial material used and pyrolysis conditions, is crucial to identify the most suitable application of biochar in soil. A selection of organic wastes with different characteristics (e.g., rice husk (RH), rice straw (RS), wood chips of apple tree (Malus pumila) (AB), and oak tree (Quercus serrata) (OB)) were pyrolyzed at different temperatures (400, 500, 600, 700, and 800 °C) in order to optimize the physicochemical properties of biochar as a soil amendment. Low-temperature pyrolysis produced high biochar yields; in contrast, high-temperature pyrolysis led to biochars with a high C content, large surface area, and high adsorption characteristics. Biochar obtained at 600 °C leads to a high recalcitrant character, whereas that obtained at 400 °C retains volatile and easily labile compounds. The biochar obtained from rice materials (RH and RS) showed a high yield and unique chemical properties because of the incorporation of silica elements into its chemical structure. The biochar obtained from wood materials (AB and OB) showed high carbon content and a high absorption character.

Revisit of the relationship between the elastic properties and sound velocities at high pressures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Chenju; Yan, Xiaozhen; Institute of Atomic and Molecular Sciences, Sichuan University, Chengdu 610065

2014-09-14

The second-order elastic constants and stress-strain coefficients are defined, respectively, as the second derivatives of the total energy and the first derivative of the stress with respect to strain. Since the Lagrangian and infinitesimal strain are commonly used in the two definitions above, the second-order elastic constants and stress-strain coefficients are separated into two categories, respectively. In general, any of the four physical quantities is employed to characterize the elastic properties of materials without differentiation. Nevertheless, differences may exist among them at non-zero pressures, especially high pressures. Having explored the confusing issue systemically in the present work, we find thatmore » the four quantities are indeed different from each other at high pressures and these differences depend on the initial stress applied on materials. Moreover, the various relations between the four quantities depicting elastic properties of materials and high-pressure sound velocities are also derived from the elastic wave equations. As examples, we calculated the high-pressure sound velocities of cubic tantalum and hexagonal rhenium using these nexus. The excellent agreement of our results with available experimental data suggests the general applicability of the relations.« less

Molecular characterization of biochars and their influence on microbiological properties of soil.

PubMed

Chintala, Rajesh; Schumacher, Thomas E; Kumar, Sandeep; Malo, Douglas D; Rice, James A; Bleakley, Bruce; Chilom, Gabriela; Clay, David E; Julson, James L; Papiernik, Sharon K; Gu, Zheng Rong

2014-08-30

The tentative connection between the biochar surface chemical properties and their influence on microbially mediated mineralization of C, N, and S with the help of enzymes is not well established. This study was designed to investigate the effect of different biomass conversion processes (microwave pyrolysis, carbon optimized gasification, and fast pyrolysis using electricity) on the composition and surface chemistry of biochar materials produced from corn stover (Zea mays L.), switchgrass (Panicum virgatum L.), and Ponderosa pine wood residue (Pinus ponderosa Lawson and C. Lawson) and determine the effect of biochars on mineralization of C, N, and S and associated soil enzymatic activities including esterase (fluorescein diacetate hydrolase, FDA), dehydrogenase (DHA), β-glucosidase (GLU), protease (PROT), and aryl sulfatase (ARSUL) in two different soils collected from footslope (Brookings) and crest (Maddock) positions of a landscape. Chemical properties of biochar materials produced from different batches of gasification process were fairly consistent. Biochar materials were found to be highly hydrophobic (low H/C values) with high aromaticity, irrespective of biomass feedstock and pyrolytic process. The short term incubation study showed that biochar had negative effects on microbial activity (FDA and DHA) and some enzymes including β-glucosidase and protease. Published by Elsevier B.V.

Effect of weld line positions on the tensile deformation of two-component metal injection moulding

NASA Astrophysics Data System (ADS)

Manonukul, Anchalee; Songkuea, Sukrit; Moonchaleanporn, Pongporn; Tange, Makiko

2017-12-01

Knowledge of the mechanical properties of two-component parts is critical for engineering functionally graded components. In this study, mono- and two-component tensile test specimens were metal injection moulded. Three different weld line positions were generated in the two-component specimens. Linear shrinkage of the two-component specimens was greater than that of the mono-component specimens because the incompatibility of sintering shrinkage of both materials causes biaxial stresses and enhances sintering. The mechanical properties of 316L stainless steel were affected by the addition of a coloured pigment used to identify the weld line position after injection moulding. For the two-component specimens, the yield stress and ultimate tensile stress were similar to those of 316L stainless steel. Because 316L and 630 (also known as 17-4PH) stainless steels were well-sintered at the interface, the mechanical properties of the weaker material (316L stainless steel) were dominant. However, the elongations of the two-component specimens were lower than those of the mono-component specimens. An interfacial zone with a microstructure that differed from those of the mono-material specimens was observed; its different microstructure was attributed to the gradual diffusion of nickel and copper.

Calcium phosphate coatings on magnesium alloys for biomedical applications: a review.

PubMed

Shadanbaz, Shaylin; Dias, George J

2012-01-01

Magnesium has been suggested as a revolutionary biodegradable metal for use as an orthopaedic material. As a biocompatible and degradable metal, it has several advantages over the permanent metallic materials currently in use, including eliminating the effects of stress shielding, improving biocompatibility concerns in vivo and improving degradation properties, removing the requirement of a second surgery for implant removal. The rapid degradation of magnesium, however, is a double-edged sword as it is necessary to control the corrosion rates of the materials to match the rates of bone healing. In response, calcium phosphate coatings have been suggested as a means to control these corrosion rates. The potential calcium phosphate phases and their coating techniques on substrates are numerous and can provide several different properties for different applications. The reactivity and low melting point of magnesium, however, require specific parameters for calcium phosphate coatings to be successful. Within this review, an overview of the different calcium phosphate phases, their properties and their behaviour in vitro and in vivo has been provided, followed by the current coating techniques used for calcium phosphates that may be or may have been adapted for magnesium substrates. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Lifetime Measurement of HgCdTe Semiconductor Material

DTIC Science & Technology

2012-03-01

long-wavelength (>15 μm) infrared spectral region. HgCdTe is a very effective infrared detector material because of its different properties. The...properties that make HgCdTe an effective infrared detector are its adjustable bandgap of 0.7 to 25 μm, its high absorption coefficient, its moderate... HgCdTe infrared detectors . Retrieved Jul. 17, 2011, from http://www.wat.edu.pl/review/optor/10(3)159.pdf Wagner, R. J. (1999 Apr. 16). In

Conjugated Organosilicon Materials for Organic Electronics and Photonics

NASA Astrophysics Data System (ADS)

Ponomarenko, Sergei A.; Kirchmeyer, Stephan

In this chapter different types of conjugated organosilicon materials possessing luminescent and/or semiconducting properties will be described. Such macromolecules have various topologies and molecular structures: linear, branched and hyperbranched oligomers, polymers, and dendrimers. Specific synthetic approaches to access these structures will be discussed. Special attention is devoted to the role of silicon in these structures and its influence on their optical and electrical properties, leading to their potential application in the emerging areas of organic and hybrid electronics.

Application of High-Density Electropulsing to Improve the Performance of Metallic Materials: Mechanisms, Microstructure and Properties

PubMed Central

Sheng, Yinying; Hua, Youlu; Zhao, Xueyang; Chen, Lianxi; Zhou, Hanyu; Wang, James; Berndt, Christopher C.; Li, Wei

2018-01-01

The technology of high-density electropulsing has been applied to increase the performance of metallic materials since the 1990s and has shown significant advantages over traditional heat treatment in many aspects. However, the microstructure changes in electropulsing treatment (EPT) metals and alloys have not been fully explored, and the effects vary significantly on different material. When high-density electrical pulses are applied to metals and alloys, the input of electric energy and thermal energy generally leads to structural rearrangements, such as dynamic recrystallization, dislocation movements and grain refinement. The enhanced mechanical properties of the metals and alloys after high-density electropulsing treatment are reflected by the significant improvement of elongation. As a result, this technology holds great promise in improving the deformation limit and repairing cracks and defects in the plastic processing of metals. This review summarizes the effect of high-density electropulsing treatment on microstructural properties and, thus, the enhancement in mechanical strength, hardness and corrosion performance of metallic materials. It is noteworthy that the change of some properties can be related to the structure state before EPT (quenched, annealed, deformed or others). The mechanisms for the microstructural evolution, grain refinement and formation of oriented microstructures of different metals and alloys are presented. Future research trends of high-density electrical pulse technology for specific metals and alloys are highlighted. PMID:29364844

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silva, F. S.

Functionally graded components exhibit spatial variations of mechanical properties in contrast with, and as an alternative to, purely homogeneous components. A large class of graded materials, however, are in fact mostly homogeneous materials with property variations (chemical or mechanical) restricted to a specific area or layer produced by applying for example a coating or by introducing sub-surface residual stresses. However, it is also possible to obtain graded materials with a smooth transition of mechanical properties along the entire component, for example in a 40 mm component. This is possible, for example, by using centrifugal casting technique or incremental melting andmore » solidification technique. In this paper we will study fully metallic functionally graded components with a smooth gradient, focusing on fatigue crack propagation. Fatigue propagation will be assessed in the direction parallel to the gradation (in different homogeneous layers of the functionally graded component) to assess what would be fatigue crack propagation on the direction perpendicular to the gradation. Fatigue crack growth rate (standard mode I fatigue crack growth) will be correlated to the mode I stress intensity factor range. Other mechanical properties of different layers of the component (Young's modulus) will also be considered in this analysis. The effect of residual stresses along the component gradation on crack propagation will also be taken into account. A qualitative analysis of the effects of some important features, present in functionally graded materials, will be made based on the obtained results.« less

Comparison between the basic least squares and the Bayesian approach for elastic constants identification

NASA Astrophysics Data System (ADS)

Gogu, C.; Haftka, R.; LeRiche, R.; Molimard, J.; Vautrin, A.; Sankar, B.

2008-11-01

The basic formulation of the least squares method, based on the L2 norm of the misfit, is still widely used today for identifying elastic material properties from experimental data. An alternative statistical approach is the Bayesian method. We seek here situations with significant difference between the material properties found by the two methods. For a simple three bar truss example we illustrate three such situations in which the Bayesian approach leads to more accurate results: different magnitude of the measurements, different uncertainty in the measurements and correlation among measurements. When all three effects add up, the Bayesian approach can have a large advantage. We then compared the two methods for identification of elastic constants from plate vibration natural frequencies.